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[Display omitted] Aerosols greatly influence precipitation characteristics, thereby impacting the regional climate and human life. As an indispensable factor for cloud formation and a critical radiation budget regulator, aerosols can affect precipitation intensity, frequency, geographical distribution, area, and time. However, discrepancies exist among current studies due to aerosol properties, precipitation types, the vertical location of aerosols and meteorological conditions. The development of technology has driven advances in current research, but understanding the aerosol effects on precipitation remain complex and challenging. This paper revolves around the following topics from the two perspectives of Aerosol-Radiation Interaction (ARI) and Aerosol-Cloud Interaction (ACI): (1) the influence of different vertical locations of absorbing/scattering aerosols on the atmospheric thermal structure; (2) the fundamental theories of ARI reducing surface wind speed, redistributing water vapour and energy, and then modulating precipitation intensity; (3) different aerosol types (absorbing versus scattering) and aerosol concentrations causing different precipitation diurnal and weekly variations; (4) microphysical processes (cloud water competition, invigoration effect, and evaporation cooling) and observational evidence of different effects of aerosols on precipitation intensity, including enhancing, inhibiting, and transitional effects from enhancement to suppression; and (5) how meteorology, water vapor and dynamics influencing the effect of ACI and ARI on precipitation. In addition, this review lists the existing issues and future research directions for attaining a more comprehensive understanding of aerosol effects on precipitation. Overall, this review advances our understanding of aerosol effects on precipitation and could guide the improvement of weather and climate models to predict complex aerosol-precipitation interactions more accurately. [ABSTRACT FROM AUTHOR]

Atmospheric icing, the accumulation of ice on surfaces, is a severe concern for the aviation industry. Deicing and icing prediction tools are necessary for pilots to ensure flight safety, and while there is established technology for large aircraft icing, more research is needed for smaller uncrewed aerial vehicles (UAVs). Here, we present measurements from 59 flights of a multirotor UAV into wintertime low stratus clouds of temperatures between − 3 and − 10 °C. The UAV is equipped with rotor heating to allow flights up to 10 min in icing conditions. Icing severity was quantified by using the rate of increase in battery current during icing, and was then compared with simultaneous, co-located measurements of liquid water content (LWC). LWC measurements were (a) calculated from cloud droplets measured with an in situ holographic imager on a tethered balloon system and (b) retrieved from remote sensing observations (microwave radiometer, ceilometer, cloud radar). We show that, for these environmental conditions, icing was strongly positively correlated to LWC over an LWC range of 0.02 to 0.5 g m−3, independent of temperature and mean droplet size, though droplets > 50 μm in diameter may contribute to increased icing severity. We also show that the LWC retrieved from remote sensing agrees well with the in situ measurements, indicating that remote sensing measurements can effectively be used to assess icing conditions. These are the first known measurements of multirotor UAV icing with co-located LWC measurements in natural clouds. • Icing severity quantified for a multirotor drone using the change in battery current. • Data presented from 59 flights of the drone into supercooled stratus clouds. • Icing severity was found to correlate strongly with supercooled liquid water content. [ABSTRACT FROM AUTHOR]

Wheat plays a crucial role in Morocco's food security, economic stability, and livelihoods of farming communities. Assessing key vegetation indices (as yield predictors), along with understanding potential yield, yield gap, and major determinants for this gap at regional and national scales, is vital for improving food security with resilience in variable climatic conditions. Analysing the yield gap and its causes during drought and optimal weather conditions can reduce crop failure risks and enhance productivity specially in variable rainfed production systems. This study aimed to develop scalable methodology to predict field- and landscape-level yield and yield gaps for wheat and their underlying causes examplifying Morocco's rainfed production environment combining remote sensing, machine learning, and ground information. By analysing six vegetation indices (EVI2, CGVI, MSR, NDVI, OSAVI, and RVI) derived from Sentinel-2 satellite imagery (10 m resolution) over three successive growing seasons (2018–2019, 2019–2020, and 2020–2021), the study employed advanced vegetation index models for accurate prediction of wheat yields and yield gaps at plot and on a larger regional scale within the Rabat-Sale-Kenitra region. To identify the determinants of yield gap, climate and soil datasets were merged with crop management information and the random forest model was fine-tuned and assessed for each season and cumulatively. The findings highlighted that RVI, GCVI, and NDVI vegetation indices were particularly effective in predicting wheat yields, showing the highest R2 and the lowest prediction errors (RMSE). Such predictive methodologies are crucial for policymakers to proactively plan and mitigate risk minimization and adaption plans at regional and national levels. The models predicted rainfed potential yields of 5.99, 1.53, and 4.66 t ha−1, with corresponding yield gap of 3.38, 0.73, and 1.58 t ha−1 for the seasons of 2018/2019 (favorable); 2019/2020 (drought) and 2020/2021 (favorable), respectively. Across three periods, critical factors determining yield include soil moisture, total rainfall during the crop growing period, evapotranspiration, and soil texture and carbon content. To minimize drought risks and maximize benefits during variable rainfall conditions, it is essential to implement pre-season drought forecasts, customize seeding dates based on soil moisture, adopt technologies that enhance soil moisture retention, and utilize climate-adapted farming practices in the semi-arid and arid rainfed regions. • Predicting yield gap and determinants is essential for improving resilience. • RVI, GCVI, NDVI, OSAVI, and EVI2 are top indicators for wheat yield prediction. • Yield gap of wheat varies from 1.53 to 5.99 t ha−1 in rainfed areas. • Soil moisture, rainfall and crop management are yield determinants in rainfed area. • Drought forecasting and tailored agronomy based on soil moisture are imperative. [ABSTRACT FROM AUTHOR]

The Index of Coalescence Activity (ICA) is an indicator of the microphysical state of the cloud. ICA is related to cloud base temperature and buoyancy of cloud at 500 hPa level. It is a useful parameter for making a decision on the type of seeding to be carried out. During Cloud Aerosol Interaction and Precipitation Enhancement EXperiment (CAIPEEX) over the Indian region, aircraft operations for in situ measurements of aerosols and clouds were conducted from the base station Hyderabad to cover parts of north peninsular India falling under the rain-shadow region. Special Radiosonde flights were conducted in the afternoon hours prior to aircraft operations from the locations Hyderabad and Mahabubnagar in addition to regular India Meteorological Department (IMD) Radiosonde flights at 00 UTC from Hyderabad. The parameters like cloud base height and buoyancy at 500 hPa level obtained from Radiosonde flights have been used to estimate ICA values during the period of the experiment (June to October 2009–2011). The variability of ICA has been studied using morning and afternoon sounding profiles over the rain-shadow region. Morning hours showed highly negative ICA values, as compared to noon hours. During noon time, positive ICA values are observed before monsoon onset (in 2009, monsoon onset was 21st June over the study area) and on few occasions during post-monsoon (October). Positive ICA values represent that collision-coalescence (CC) process is not fully developed and hence, hygroscopic seeding is the proper decision. While, negative ICA values indicate active CC process, suggesting glaciogenic seeding. The soundings conducted just before the cloud seeding operations provide information about the actual thermodynamic and microphysical state of the cloud. Hence, ICA information is useful for providing guidelines to the operational cloud seeding programs. • Variability of ICA is investigated over a rain-shadow region in peninsular India. • Negative ICA during monsoon represent glaciogenic seeding to trigger rainfall. • Positive ICA in pre-monsoon/weak monsoon represent hygroscopic seeding. • ICA reveals change in microphysical state of the cloud after monsoon establishment. • ICA an important indicator for making cloud seeding decisions. [ABSTRACT FROM AUTHOR]

Observation-validated cloud seeding simulation is valuable in assisting in evaluating seeding effect, but its sensitivity to microphysics schemes and cloud seeding parameterizations is rarely investigated. In this research three cloud seeding parameterizations (the Hsie, Demott and Xue parameterizations) are coupled with two microphysics schemes (the Thompson and Milbrandt schemes), to perform simulations of the rainfall suppression cloud seeding operation on a convective rainfall event occurred in North China on 1 July 2021, aiming to evaluate the seeding effect and investigate its sensitivity to microphysics schemes and seeding parameterizations. The differences of rainfall suppression effect between three seeding parameterizations are smaller than those between two microphysics schemes. The rainfall suppression ratios produced by the simulations configured with the Milbrandt scheme range from 16.3% to 24.7%, while those with the Thompson scheme range from 0.47% to 1.38%. The difference of the seeding effect between these two microphysics schemes arises from their different method in parameterizing the snow deposition growth process. In addition, in the seeding simulations with the Milbrandt scheme, the surface rainfall decrease region is followed by a rainfall increase region. This rainfall decrease-increase pattern is caused by the fact that the reduced graupel particles caused by cloud seeding falls to the ground earlier with its larger fall velocity, while the seeding-increased snow particle falls to the ground later due to its smaller fall velocity. This result suggests there is an ephemeral cloud seeding window for rainfall suppression operation. • Three cloud seeding approaches are coupled with two microphysics schemes. • Seeding effect is more sensitive to microphysics schemes than seeding approaches. • Diversity in seeding effect arises from different snow deposition parametrizations. • Ensemble cloud seeding simulation is valuable for evaluating cloud seeding effect. [ABSTRACT FROM AUTHOR]

Stratus is the main artificial seeding target for weather modification in Ningxia. Meteorological satellites can detect macro and microcosmic physical parameters of large-scale stratus. Researching precipitation and cloud parameter characteristics of stratus can provide scientific and technological support for understanding the development and evolution of stratus to identify seeding conditions and effects. Eight typical stratus precipitation events of the summers of 2016–2021 of Ningxia were selected, using the nine point average method, that matched characteristic cloud parameters retrieved by FY-2G satellite with precipitation classification data of 25 national meteorological observation stations in Ningxia. These stratus precipitation characteristics were correlated with cloud parameters. The results indicate that precipitation decreased rapidly from the southeast to the northwest of Ningxia. In the synoptic background of precipitation, the cloud top height, super-cooled layer thickness, cloud optical thickness, cloud particle effective radius, and cloud liquid water content were all larger than those in the synoptic background of no precipitation. The spatial distribution feature manifests as gradually increased from southeast to northwest. The cloud top temperature and cloud blackbody temperature were smaller than those in the synoptic background of no precipitation. The cloud top temperature was near the cloud "seeding temperature window", and the depth of the super-cooled layer was thick. This was in line with the "Seeder-Feeder" structure characteristic of cold stratus. • Nine-point mean method was used to match satellite grid data with precipitation data. • Analyzed various characteristics of ground precipitation of the stratus processes. • Studied the statistics of stratus satellite parameters with or no precipitation. • Analyzed the relationship between the magnitude of cloud parameter and precipitation. • Studied spatial features of stratus satellite parameters with or no precipitation. [ABSTRACT FROM AUTHOR]

Cloud seeding is a process that adjusts cloud physical properties and processes, including both natural and human measures. This study aims to assess the effects of natural ice seeding from upper ice-containing clouds on low convective clouds through in-situ aircraft observations during an Integrative Monsoon Frontal Rainfall Experiment (IMFRE-II) in the summer of 2020. We mainly focus on two distinct shallow convective clouds, one with and the other without upper ice-containing layer, namely Cloud A and Cloud D. The in-situ data demonstrate that snowfall from the upper ice-containing layer to the lower Cloud A, leading to significant changes in cloud top height, median value of radar echo as well as vertical velocity. Compared to shallow convective cloud D without upper-level seeding, cloud A had an approximately 84% less concentration of cloud droplets (diameter <100 μm) and had a slightly smaller cloud droplet effective diameter. For drizzle particles and cloud ice particles with sizes larger than 100 μm, cloud A had a concentration one order of magnitude larger than that of cloud D, also with a larger spectral broadening ratio. These findings reveal the influence of "Seeder-Feeder" effects on microphysical properties of cloud A. The physical mechanisms of Bergeron, riming, and coalescence most likely play a role in the rapid formation of large drizzle/precipitation particles. The natural seeding effect of "seeder-feeder" through snow-virga also likely forms local turbulence, accelerates turbulent entrainment mixing, and promotes the development of the seeded shallow convective cloud. • Ice-containing cloud favors the precipitation formation of convective cloud below. • Ice particles fasten the Bergeron process within low cloud with supercooled droplets. • Evaporation of falling particles helps invigorate the cloud development below. [ABSTRACT FROM AUTHOR]

The precipitation, microphysical, and environmental characteristics of shallow and deep precipitation clouds (SPCs and DPCs) are investigated over the Yangtze-Huaihe River during the summers from 2014 to 2021, using the observational data from dual-frequency precipitation radar (DPR) on board Global Precipitation Mission and the reanalysis data. DPCs (SPCs) are mainly associated with convective (stratiform) precipitation, contributing approximately 2% ∼ 15% (20% ∼ 40%) to the total precipitation events, while contributing only around 0.05–0.15% (below 0.05%) to the total rainfall. Compared to SPCs, the rain hydrometeors for DPCs are mainly composed of lower concentrations of larger-sized hydrometeors near the surface, showing larger mass-weighted mean diameter (D m : 1.0 to 3.0 mm) and lower generalized intercept parameter (N w : 20 to 40 dB N w) at 2 km in altitude. Below the melting layer, the D m , reflectivity, and rain rate of DPCs decrease rapidly as the decreasing altitude, reflecting the breakup or the evaporation of liquid hydrometeors, while those of SPCs rapidly increase, indicating vigorous processes of collision and coalescence. DPCs tend to occur in environmental conditions with increased convective available potential energy (CAPE) and higher surface air temperatures, but drier low-level humidity, compared to SPCs. Furthermore, the DPCs tend to occur in the environment with more significant updraft (≥5 m s−1) in comparison with SPCs. Especially at 4 km and 10 km in altitude, the updraft fractions could reach 45% and 38%, respectively. These results may provide an observational reference for the microphysical parameterization in numeric models for the vertical development of storms. • The breakup or evaporation are dominant for deep precipitation clouds (DPCs). • The collision and coalescence are predominant for shallow precipitation clouds. • High surface air temperatures and dry moisture favorable for the formation of DPCs. [ABSTRACT FROM AUTHOR]

The microphysical and dynamic evolution characteristics of two convections (labeled A and B) were analyzed using polarimetric radars during the same weather conditions under the influence of ground-based rockets and artilleries containing silver iodide (AgI). The ice and liquid water content (IWC and LWC, respectively), hydrometeor classification and three-dimensional wind structure were retrieved to analyze the convection evolution. The results indicate that the convective evolution trends after AgI seeding are related to the preoperation dynamic and microphysical structure. The ice processes of convection A are more active before operation, with a high echo center of gravity, larger IWC and LWC, and a predominance of graupel above the freezing level. The center of gravity of the convection gradually decreases, and the cloud collapses and gradually dissipates during AgI seeding. Convection B has more active liquid processes, with a stronger updraft but lower IWC and LWC. During AgI seeding, ice processes of the convection have a tendency to be enhanced, with a higher echo center of gravity and increases in IWC, and LWC below the freezing level. During significant wind shear, the path of convection may tend to align with the background guided flow at different levels, depending on the different intensities of convection influenced by AgI seeding. The convection intensity and its matching with vertical wind shear should be considered when artificially seeding convection. • Polarimetric radars aid convection evolution analysis during AgI seeding of rockets and artillery • Convection evolution trends relate to its dynamic and microphysical structure before AgI seeding • Seeding convection may affect its trajectory depending on the environmental wind shear [ABSTRACT FROM AUTHOR]

Precision farming technologies have the potential to enhance agricultural sustainability, but their exact environmental impact remains uncertain. This study aimed to (1) compare the life cycle assessment (LCA) of a conventional five-year crop rotation system with and without precision agriculture technologies (PATs) in Lower Austria; (2) to assess the emission hotspots and (3) to perform a sensitivity analysis on fertilization using the DeNitrification-DeComposition (DNDC) soil model to quantifying soil emission. Evaluated PATs included automatic steering systems, automatic section control (ASC), proximal sensors, and prescription maps from remote sensors. The crop rotation system included spring barley, soy, winter wheat, rapeseed, and winter barley. Assessed agricultural processes encompassed tillage, seeding, plant protection, fertilization, and harvesting. The impacts evaluated were climate change, fine particulate matter formation, freshwater eutrophication, freshwater ecotoxicity, terrestrial acidification, terrestrial ecotoxicity, and human carcinogenic toxicity. The sensor scheme scenario showed the highest reductions in climate change, followed by the prescription map, ASC, and autosteer scheme with reductions of −17.0, −8.9, −6.4, and −2.4%, respectively. This study emphasizes the potential of PATs to minimize environmental impacts in crop production while recognizing the influence of site and technology-specific factors. Future research should consider local variables for a comprehensive environmental assessment. • The environmental impacts of four precision agriculture technologies are assessed. • Life cycle assessment is used with the DeNitrification-DeComposition soil model. • Crop sensors, optimal in precision agriculture, cut global warming by −17.04%. • Precision farming effectiveness depends on site-and technology-specific factors. [ABSTRACT FROM AUTHOR]

Time series prediction of rain attenuation from rain rate measurement during rain is made by using Synthetic Storm Technique (SST) for Ka and Q band signal for a temperate location, Vigo, Spain. Rain rate and rain attenuation data for the three year measurement period from 2016 to 2018 have been used to test the validity of the SST model at the present location. As we move from the Ka band to the Q band, larger value of predicted rain attenuation for the same rain rate is observed. For a single rain event, better prediction depends on the actual storm speed measured for the present location. But the long term statistics of predicted rain attenuation are insensitive to storm translation speed. Applicability of the SST model is tested for predicting diurnal, monthly and yearly statistics. Comparison between prediction and measurements are done for both first (rain attenuation occurrence) and second order (fade duration) statistics. Good matching has been observed between prediction and measurement for single rain event as well as for long term statistics. Prediction errors are found to be less than 0.5 dB in all the cases which proves the efficiency of the SST model for the present location. [ABSTRACT FROM AUTHOR]

• While global food production depends increasingly on pollinators, agricultural intensification causes their decline and limits productivity of pollinator dependent crops. • Pollinator loss can cause degradation of surrounding ecosystems causing further decrease of yields. • Climate change requires us to look beyond the plant and preserve the functioning of ecosystems. • Pollinators are key-agents for climate change adaptation of agro-ecosystems. • Farming with Alternative Pollinators (FAP) is a new low-cost approach for higher productivity of pollinator-dependent crops and climate resilient agro-ecosystems. Within global crop production 1961–2012, the share of pollinator independent crops increased twofold, but fourfold of pollinator dependent crops. Balanced diets within the boundaries of our planet require even more pollinator dependent crops. Particularly, Low and Middle Income Countries in the drylands produce pollinator dependent crops. However, climate change and agriculture increasingly cause risks for pollinators. Common reward-based seeding of wildflower strips is too expensive for these countries. Breeding towards pollinator independent crops might accelerate loss of pollinators. Recent publications warned that pollinator loss can reduce other ecosystem services supporting crop production. A new alternative approach called Farming with Alternative Pollinators (FAP) might fill the gap. FAP creates on-farm habitable conditions for pollinators and increases productivity and incomes per surface. [ABSTRACT FROM AUTHOR]

Highlights • The corona losses of bundle conductors were measured at an altitude of 2200 m. • Dryness, artificial rain and a wet conductor were considered in the measurement. • The field strength in UHV corona cage and actual transmission lines were calculated. • The corona losses on the UHV AC double-circuit transmission lines were evaluated. • The optimal selection of conductor types was provided for high-altitude areas. Abstract Corona loss is the key parameter for evaluating operating economy of ultra-high voltage (UHV) and extra-high voltage (EHV) alternating current (AC) transmission lines and is one of important factors that need to be considered in line design and operation. At present, corona losses of 8 × LGJ-630 conductors, which are commonly used in ultra-high voltage alternating current (UHV AC) double-circuit transmission lines on the same tower, and 8 × LGJ-720, and 10 × LGJ-720 bundle conductors with a larger cross-section and more bundle number in high-altitude areas have not yet been studied. In the paper, the corona losses of the 8 × LGJ-630, 8 × LGJ-720, and 10 × LGJ-720 conductors were measured under conditions of dryness, artificial moderate rain, heavy rain and a wet conductor, based on the UHV corona cage built in Ping'an County, Xi'ning, China at an altitude of 2,200 m. By taking typical 1,000 kV UHV-AC double-circuit transmission lines on the same tower as an example, the electric field strengths on the surface of conductors in the corona cage and the actual lines were calculated. On this basis, the corona loss of the UHV-AC double-circuit transmission line in a high-altitude area was analyzed. The research results can provide data reference for constructing UHV transmission lines in high-altitude areas. [ABSTRACT FROM AUTHOR]

Severe droughts are increasingly frequent around the world, in particular in the desert area. There is a shortage of water that can be partly avoided by the implementation of precipitation enhancement projects. The concept implies cloud seeding with appropriate artificially produced aerosols. The main lack of that methodology is a scientific basis of the evaluation of seeding effects. The twofold contributions of this paper are the following: (1) introducing a new one-dimensional (1D) numerical model for cloud seeding experiments (1D MCSE) and (2) testing the performances of a novel aerosol at enhancing surface precipitation using the 1D MCSE. The novel aerosol is core/shell sodium chloride (NaCl)/titanium dioxide (TiO 2 ) nanostructure, also known as the shell structured TiO 2 /NaCl. The introduced numerical model is a coupled dynamics and microphysics scheme. Two principally different approaches of numerically simulating the performances of the shell structured TiO 2 /NaCl are utilized in this paper. In the first approach the cloud droplet nucleation on the novel aerosols is evaluated via the lookup tables which were constructed by using the parcel model. The activation characteristics were modelled as function of ambient temperature, vertical velocity, relative humidity, the number of aerosols, and their chemical characteristics expressed by kappa parameter. In the second approach, the activation features of shell structured TiO 2 /NaCl are explicitly resolved in the MCSE 1D model using the diffusion equation constructed from the laboratory experiments in cloud chambers with this novel aerosol. The performances of the novel aerosols were compared against the pure NaCl that has traditionally been used for precipitation enhancement, as well as against the base case without any seeding (i.e., cloud droplet nucleation only on the natural aerosols). In all analyzed cases, the novel aerosol shows profoundly better performances as precipitation enhancer than the pure NaCl. The superiority of this novel seeding material to pure NaCl is particularly noticeable in the unsaturated environments with the relative humidity below 75%. Analysis of spatiotemporal windows for these two artificial aerosols shows that the resulting precipitation enhancement from the shell structured TiO 2 /NaCl is >15% larger than using the pure NaCl and about 30% larger than in natural case. In addition, this paper demonstrates a large flexibility of the 1D MCSE to produce a variety of different outputs which are of great importance in the cloud seeding experiments. [ABSTRACT FROM AUTHOR]

Understanding rill erosion processes is important in the prediction of soil erosion and the prevention of soil loss. However, limited information is available concerning the impacts of rainfall on rill erosion on steep slopes. Colluvial deposits with steep slopes make up the packed material underlying the collapsing walls in benggang , which collapse due to hydraulic pressure and gravity. They contain loose materials and large amounts of coarse particles. The objectives of this study were to investigate the impacts of rainfall intensity and slope gradient on the rill erosion process, rill development and rill flow dynamic mechanisms on the steep slopes of colluvial deposits. The colluvial soils were subjected to simulated rainfall in a 5-m 2 (5-m by 1-m) flume at heavy rainfall intensities (100, 120, and 140 mm h −1 ) and on five steep slopes (20, 25, 30, 35, and 40°). Rill erosion contributed significantly to colluvial slope erosion; on average, rills accounted for 61% of the soil loss, and the effects of slope gradient were greater than those of the rainfall intensity. After rill development, rill density, rill length, width, and depth all significantly increased. Correspondingly, the soil loss rate sharply raised and irregularly fluctuated. Moreover, the collapse of rill heads or sidewalls tended to increase the relative contribution to rill erosion and rill development. The rill flow was characterized by transitional and subcritical flow regimes. The rill flow velocity was the most sensitive hydraulic parameter, and the unit stream power provided the optimal hydrodynamic parameter to characterize the dynamic mechanisms of rill erosion on colluvial deposits. The collapse of rill heads or sidewalls could result in negative values for critical shear stress, critical stream power, and critical unit stream power of rill erosion, which were −19 Pa, −5.3 N m −1  s −1 , and −0.09 m s −1 , respectively. These results provide a better understanding of the mechanism of rill erosion on steep slopes. [ABSTRACT FROM AUTHOR]

We successfully implemented a framework involving an uncrewed aircraft system (UAS) with atmospheric and cloud microphysical sensing and autonomous adaptive control technologies to search, identify, carry out, monitor and/or evaluate cloud seeding operations to enhance precipitation. This first-time implementation featured trials in the U.S. Great Plains area following the US aviation authority regulations during a three-week summer trial period. The trials provide insight into using UAS in an operational setting. Their broader significance is a step toward improved targeting efficiency, and hence improved operational cloud seeding activity effectiveness. The implementation of the integrated UAS provide and exploit the temporal and spatial cloud-scale sensitivities information to overcome the operational and natural uncertainties or sparseness of environmental parameters needed to increase cloud seeding operational efficiency. • First demonstration of autonomous uncrewed aircraft systems (UAS) for operational rain enhancement. • UAS with Wx and cloud sensors, autonomous-adaptive control tech repeated successful operational cloud seeding maneuvers. • Two UAS with Wx and cloud sensors, autonomous-adaptive control tech repeated successful operational cloud seeding maneuvers. • UAS with Wx and cloud sensors, autonomous-adaptive control tech may lower cloud seeding operational footprint. • UAS with Wx and cloud sensors, autonomous-adaptive control tech may improve cloud seeding targeting efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a nonlinear deterministic mathematical model along with its stochastic version for artificial rain is proposed and analyzed. We have considered three dynamical variables in the modeling process; namely (i) density of cloud droplets, (ii) density of raindrops, and (iii) concentration of mixture of conducive aerosols. It is assumed that the cloud droplets are continuously formed in the atmosphere at a constant rate but its conversion into raindrops does not take place in the same proportion. The artificially introduced aerosols increase the rate of formation of raindrops from cloud droplets. These aerosols are introduced in the regional atmosphere at a rate proportional to the density of cloud droplets. The proposed model is analyzed using stability theory of differential equations in deterministic as well as stochastic environment. Numerical simulation is performed to see the effect of important parameters on the process leading to rainfall. [ABSTRACT FROM AUTHOR]

In this paper, the possible solutions aimed at ensuring water security and sustainability in the UAE are proposed and assessed. The proposed solutions include the introduction of cost-reflective water price regimes, sustainable building codes, total wastewater reuse, leakage reduction, and diversification of supply sources in terms of renewable energy-powered desalination and cloud seeding. The feasibility of these solutions is assessed in terms of the drivers and barriers to their implementation. From the assessments, it is observed that the implementation of the actual cost of water (AED10.32/m 3 ) would reduce water consumption by expats by 5.4%. Significant reduction in water consumption by locals could also be achieved. Domestic water savings, up to 19.8%, would be achieved by water-efficient household fixtures. Irrigation can be achieved through complete wastewater reuse and water leakage can be reduced to 10% through noise loggers, automated pumps, and pressure relief valves. A water management approach that integrates these solutions is crucial and strategic to the attainment of sustainable water balance. [ABSTRACT FROM AUTHOR]

This paper describes a stochastic ice accretion method to model in-flight ice accretion. The approach consists in complementing the deterministic quasi-steady process generally used to simulate ice accretion by treating the effects of water-droplet deposition and freezing on the ice growth in a stochastic and unsteady manner. The baseline algorithm thus features an unstructured advancing front technique modeling the freezing of individual water particles. Stochasticity is introduced in the seeding process by generating a random initial position and diameter for each injected particle. The particles are treated sequentially and their impingement position is obtained from their trajectory, which is extracted as a streamline of the deterministic quasi-steady droplet velocity field computed by an Eulerian droplet impingement model. The thermodynamic state of the deposited water is then assessed and an advancing front algorithm is used to generate the corresponding elements of ice, which allows capturing the unsteady behavior of the ice growth. The mass of water to be frozen is given by the freezing fraction, computed by the deterministic quasi-steady approach, the remaining mass flowing downstream until the particle is completely frozen. Unlike deterministic approaches, the process treats the ice density as a dependent variable. The verification of the model shows its convergence according to the ice element size, which is the main computational parameter. An extended 2D model is presented to cater for 3D effects by introducing the concept of permeability of the ice front. Validation is performed by comparing the obtained ice shapes to the experimental results for four test cases of the literature. The method successfully captures both rime and glaze ice geometries. Finally, the stochasticity observed in the experimental ice shapes and the formation of discrete ice structures are well captured, which are usually missed by the state-of-the-art deterministic icing frameworks. • Stochasticity in the modeling of in-flight ice accretion is often neglected in icing software. • Variability observed in experimental ice shapes is therefore not modeled. • The ice accretion modeling in a building block manner enables the introduction of stochasticity. • Introduction of stochasticity in the impingement allows to model stochastic ice shapes. [ABSTRACT FROM AUTHOR]

Weather Research and Forecasting Model (WRF) coupled with a silver iodide (AgI) cloud-seeding scheme was used to simulate a precipitation enhancement of stratiform clouds with embedded convection(referred to as "SEC" hereinafter) in Beijing on May 29th, 2012. The seeding effect and its mechanisms were analyzed, and several sensitivity tests were performed to investigate the effects of dust, seeding amount, and seeding position on clouds and precipitation. When an amount of 100 g AgI was seeded in the convective region of the case in this study, rainfall decreased from 0.5 h to 1.5 h after seeding, and then increased in the following 1.5 h. The increment of the surface rainfall is mainly resulted from the melting of snow and graupel. Among the four ice nucleation mechanisms, condensation freezing is the most dominant, followed by contact freezing, and the deposition nucleation was the weakest. The seeding amount of AgI had a strong effect on the rainfall enhancement, and a moderate seeding amount of about 500 g is suggested. A further increase or decrease of AgI leads to a decrease of rainfall enhancement. We also found seeding in the clean air had more remarkable effects than under the dusty condition. Regarding the seeding position, seeding in the convection region was more prominent in enhancing rainfall, followed by seeding the convection entry region, and seeding in the stratus region has the least effect. These results reveal the seeding microphysical processes of SEC providing a guidance for weather modification operations. • Condensation freezing is the most dominant among the four ice nucleation mechanisms. • Seeding amount had effects on the rainfall enhancement, about 500 g AgI is suggested. • Seeding in the convection region was more prominent in enhancing rainfall. [ABSTRACT FROM AUTHOR]

The first phase of the Snowy Precipitation Enhancement Research Project (SPERP-1) was a confirmatory experiment on winter orographic cloud seeding (Manton et al., 2011). Analysis of the data (Manton and Warren, 2011) found that a statistically significant impact of seeding could be obtained by removing any 5-hour experimental units (EUs) for which the amount of released seeding material was below a specified minimum. Analysis of the SPERP-1 data is extended in the present work by first considering the uncertainties in the measurement of precipitation and in the methodology. It is found that the estimation of the natural precipitation in the target area, based solely on the precipitation in the designated control area, is a significant source of uncertainty. A systematic search for optimal predictors shows that both the Froude number of the low-level flow across the mountains and the control precipitation should be used to estimate the natural precipitation. Applying the optimal predictors for the natural precipitation, statistically significant impacts are found using all EUs. This approach also supports a novel analysis of the sensitivity of seeding impacts to environmental variables, such as wind speed and cloud top temperature. The spatial distribution of seeding impact across the target is investigated. Building on the results of SPERP-1, phase 2 of the experiment (SPERP-2) ran from 2010 to 2013 with the target area extended to the north along the mountain ridges. Using the revised methodology, the seeding impacts in SPERP-2 are found to be consistent with those in SPERP-1, provided that the natural precipitation is estimated accurately. [ABSTRACT FROM AUTHOR]

This paper builds upon the processes and framework already established for identifying, integrating and testing an unmanned aircraft system (UAS) with sensing technology for use in rainfall enhancement cloud seeding programs to carry out operational activities or to monitor and evaluate seeding operations. We describe the development and assessment methodologies of an autonomous and adaptive UAS platform that utilizes in-situ real time data to sense, target and implement seeding. The development of a UAS platform that utilizes remote and in-situ real-time data to sense, target and implement seeding deployed with a companion UAS ensures optimal, safe, secure, cost-effective seeding operations, and the dataset to quantify the results of seeding. It also sets the path for an innovative, paradigm shifting approach for enhancing precipitation independent of seeding mode. UAS technology is improving and their application in weather modification must be explored to lay the foundation for future implementation. The broader significance lies in evolving improved technology and automating cloud seeding operations that lowers the cloud seeding operational footprint and optimizes their effectiveness and efficiency, while providing the temporal and spatial sensitivities to overcome the predictability or sparseness of environmental parameters needed to identify conditions suitable for seeding, and how such might be implemented. The dataset from the featured approach will contain data from concurrent Eulerian and Lagrangian perspectives over sub-cloud scales that will facilitate the development of cloud seeding decision support tools. [ABSTRACT FROM AUTHOR]

Recently, a new meta-heuristic approach, known as artificial raindrop algorithm (ARA), was proposed. This approach is inspired by the natural rainfall phenomenon, and has been observed to be a powerful tool in solving single-objective optimization problems. In this paper, a multi-objective variant of ARA (MOARA) is developed, which primarily combines the search mechanism of ARA and the non-dominated sorting technique, in an attempt to demonstrate the potential of ARA in tackling multi-objective optimization problems (MOPs). To improve the exploratory ability, the center point sampling strategy (CPSS) together with simulated binary crossover (SBX) is integrated into MOARA. The primary role of SBX is to accelerate the filling of the Pareto front (PF) by recombining diverse solutions, whereas CPSS serves as the domain knowledge of the MOP for guiding other points toward the target PF. For performance evaluation and comparison purposes, the proposed approach has been applied to two sets of benchmark MOPs, and compared with eight state-of-the-art multi-objective evolutionary algorithms based on the non-dominated sorting. The experimental results have indicated its improved efficiency over the other compared approaches. Furthermore, the contributions of SBX and CPSS to the entire algorithm have been experimentally studied. Finally, the proposed technique is applied to dynamic optimization problems in chemical processes, and promising results show the method's potential in real-world applications. [ABSTRACT FROM AUTHOR]

Deep convection yielding severe weather phenomena (hail, flash floods, thunder) is frequent in Serbia during the warmer part of the year, i.e. April to September. As an effort to mitigate any potential damage to material goods, agricultural crops and vegetation from larger hailstones, cloud seeding is performed. In this paper, we analyzed 29 severe hailstorms seeded by silver iodide. From these, we chose five intense summer thunderstorm cells to analyze in detail the influence of silver-iodide cloud seeding on the radar parameters. Four of them were seeded and one was not. We also used data from firing stations (hail fall occurrence, the size of the hailstones). The most sensitive radar parameter in seeding was the height where maximum reflectivity in the cloud was observed. Its cascade appeared in every case of seeding, but was absent from the non-seeded case. In the case of the supercell, increase and decrease of the height where maximum reflectivity in the cloud was observed occurred in almost regular intervals, 12 to 15 min. The most inert parameter in seeding was maximum radar reflectivity. It changed one to two dBz during one cycle. The height of the top of the cloud and the height of the zone exhibiting enhanced radar echo both had similar behavior. It seems that both increased after seeding due to a dynamic effect: upward currents increasing due to the release of latent heat during the freezing of supercooled droplets. Mean values of the height where maximum reflectivity in the cloud was observed, the height of the top of the cloud and the height of the zone exhibiting enhanced radar echo during seeded period were greater than during unseeded period in 75.9%, 72.4% and 79.3% cases, respectively. This is because the values of the chosen storm parameters were higher when the seeding started, and then those values decreased after the seeded was conducted. [ABSTRACT FROM AUTHOR]

Purpose Phosphorus (P) lost from agricultural land by erosion, runoff, throughflow and leaching is of major concern for water resource managers worldwide. Previous study on soils from cropping land of southwest Western Australia suggested P loss as dissolved unreactive P (DURP) via leaching, but the implications for processes and rates of P transport in soils are not known. Material and methods Two contrasting soil profiles (sand and loam) from cropping land of southwest Western Australia were exposed to artificial rain in packed boxes and field runoff plots to examine P forms and fluxes in runoff, throughflow, leachate and soil solution after three P rates of application (equivalent to 0, 20 and 40 kg P/ha). Solutions were analyzed for total P (TP), dissolved reactive P (DRP) and total dissolved P (TDP). Particulate P (PP) and DURP were calculated by subtracting DRP from TP and TDP respectively. Result and discussion In the sand profile, about 90% or more of P losses via runoff and leachate were in DURP and PP forms, whereas DRP was a minor contributor. Phosphorus load in soil solution, throughflow, leachate and run-off increased with increasing P rate. The relatively higher affinity of soil for DRP compared to DURP might cause the latter to be more mobile through profile in association with colloidal compounds < 0.2 μm. Higher PP concentration for loam soil via throughflow is exacerbated by dispersed clay, which could be an additional process influencing P mobility in loam and duplex soils. Conclusion The DRP played a limited role in P transport compared to PP and DURP that both appeared to be associated with soil particles or soil colloids in runoff, throughflow, leachate and soil solution. Further characterization of the latter forms of P is needed so that management practices can be developed to minimize P losses. [ABSTRACT FROM AUTHOR]

The AgI Seeding Cloud Impact Investigation (ASCII) campaign, conducted in early 2012 and 2013 over two mountain ranges in southern Wyoming, was designed to examine the impact of ground-based glaciogenic seeding on snow growth in winter orographic clouds. Part I of this study ( Pokharel and Geerts, 2016 ) describes the project design, instrumentation, as well as the ambient atmospheric conditions and macrophysical and microphysical properties of the clouds sampled in ASCII. This paper (Part II) explores how the silver iodide (AgI) seeding affects snow growth in these orographic clouds in up to 27 intensive operation periods (IOPs), depending on the instrument used. In most cases, 2 h without seeding (NOSEED) were followed by 2 h of seeding (SEED). In situ data at flight level (2D-probes) indicate higher concentrations of small snow particles during SEED in convective clouds. The double difference of radar reflectivity Z (SEED − NOSEED in the target region, compared to the same trend in the control region) indicates an increase in Z for the composite of ASCII cases, over either mountain range, and for any of the three radar systems (WCR, MRR, and DOW), each with their own control and target regions, and for an array of snow gauges. But this double difference varies significantly from case to case, which is attributed to uncertainties related to sampling representativeness and to differences in natural trends between control and target regions. We conclude that a sample much larger than ASCII's sample is needed for clear observational evidence regarding the sensitivity of seeding efficacy to atmospheric and cloud conditions. [ABSTRACT FROM AUTHOR]

The hygroscopic cloud seeding is conducted over the rain shadow region of the Indian peninsula with an airborne field experiment and radar observations. Physical evaluation of hygroscopic seeding is illustrated with in situ microphysical observations and numerical simulations in convective clouds. Large raindrops were formed near the tops of the cloud, as documented by aircraft observations and model simulations with spectral bin microphysics scheme. Scattering particle number concentration and refractory black carbon in the cloud residue were found up to 4 km in the seeded cloud. The cloud residue measurements of scattering particles and the cloud droplet number concentration showed good agreement in the cloud cores and that has reduced drastically in the cloud edges. Numerical simulations with bin microphysics using observed (background and flare) particle spectra were conducted. Fairly good agreement is noted for the cloud drop size distributions from in situ measurements and numerical simulation. The clouds developed downwind of the seeded area showed further organized convection and longevity and relative enhancement of rainfall as illustrated by the radar observations and the numerical simulations compared to unseeded clouds. The investigation has also brought out the nonlocal impact of the seeded plumes and the new challenges in documenting extra area effects of seeding in the monsoon environment. • Physical evaluation of hygroscopic seeding in Indian monsoon clouds. • Seeding signature identified in the cloud residue and in situ microphysics. • The extra area effects are noted in precipitation and cloud-seeding plumes. [ABSTRACT FROM AUTHOR]

• Climate warming led to northward shift of the northern limits for dou ble rice. • Anticipated technological transitions offset the effects of climate warming. • The early and medium rice maturity classes were most impacted by planting methods. • The rice planting areas may decrease by 13.3% due to changes in planting methods. Evaluation of and adaptation to climate warming have become major challenges, given the profound impacts of climate warming and technical advances in rice cropping systems. However, the dual influences of climate warming and planting methods on rice production remain unclear. Here, we developed a methodological framework based on temperature-based rice growth season determination and GIS spatial analysis to quantify the effect of climate warming and improvements in planting methods (transplanting to direct seeding) on the potential distribution of rice cropping systems in South China from 1960 to 2017. The accumulated temperature during the potential growing period of rice increased significantly, and the safe season for rice production extended substantially, which resulted in northward and westward expansions of the planting boundaries for rice cropping systems over the past few decades. Significant changes in planting boundaries and potential planting areas were observed for early maturity double rice (DR_Early) because of climate warming. Since transplanting requires less thermal time compared to direct seeding in the main field, the planting boundaries of DR would shift southward because of planting methods change. The planting boundaries of DR_Early and medium maturity double rice (DR_Medium) changed significantly, moving on average 267 and 159 km southward, resulting in a 13.3% decrease in the study area. The dual analysis showed that the change in planting methods would shift the rice planting boundaries southward, offset the impact of climate warming, and reduce the rice planting areas by 4.0%. Therefore, improvements in planting methods should be considered when evaluating the effects of climate warming on agricultural systems. This research provides new insights that could be used to optimize rice cropping systems, improve the utilization efficiency of thermal resources and adapt to climate warming. [Display omitted] [ABSTRACT FROM AUTHOR]

The frequency of rain-on-snow (ROS) occurrence is increasing and this natural phenomenon is beginning to play an important role in temperate climate regions. Present knowledge of outflow generation mechanisms and rainwater dynamics during ROS is still insufficient. The study introduces a combined method of artificial ROS, isotopic tracing and energy balance to partition the event rainwater and the pre-event non-rainwater in the outflow. A rainfall simulator and water enriched with deuterium were used for identifying event rainwater and pre-event non-rainwater during an ROS event. The ROS experiment was conducted in the Krkonoše Mountains in the Czech Republic. An experimental snow block consisting of ripe and isothermal snow was sprayed with deuterium enriched water. The outflow from the snowpack was continuously monitored to gain quantitative and qualitative information about outflow water. The isotopic deuterium content was further analysed from the samples by means of laser spectroscopy in order to separate the hydrograph components. The deuterium content was also analysed from the snow samples gathered before and after the experiment to identify the retention of event rainwater in the snowpack. Isotopic hydrograph separation revealed that although high rain intensity was applied, the event rainwater represented one half (52.7%) of the total outflow volume. The ripe snowpack retained about one third of the rainwater input (33.6%). Significant changes in the outflowing water quality can therefore be expected during ROS events. This experiment also shows that rainwater during ROS firstly pushes-out the non-rainwater and then contributes to the outflow. These results show that the presented technique allows us to gain sufficient information about rainwater dynamics during ROS. [ABSTRACT FROM AUTHOR]

In this study, the performances and uncertainties of cloud microphysics parameterization (MP) schemes for simulating cloud macrophysics associated with mixed convective-stratiform cloud (MCSC) events are investigated. MCSC system is the primary object of cloud seeding for the purpose of rain enhancement in North China. Understanding the forecast uncertainties of cloud macrophysics, such as cloud top temperature (CTT), cloud base height (CBH), and cloud optical thickness (COT), is of great significance for cloud seeding operations. Simulations of cloud macrophysics are verified using cloud data retrieved from the Feng-Yun-2F geostationary meteorological satellite, radiosondes and Moderate Resolution Imaging Spectroradiometer (MODIS) products. The performances of several MP schemes to accurately simulate cloud macrophysics within ensemble forecasts is explored using both grid-wise and object-based metrics. Large differences are found among schemes in simulated cloud macrophysics compared with similar performances in simulated precipitation. In most cases, the ensemble mean simulates more realistically than each single scheme. The ensemble spread varies somewhat according to the simulated variables. For CBH, the ensemble shows adequate ensemble spread, while relative underdispersion occurs for CTT and COT. Detailed COT comparisons of reveal that COT bias mainly comes from the contribution of cloud droplets and snow. The causes of COT bias are further investigated by a detailed comparison of the cloud water path (CWP) and cloud effective radius (EFFR). The study establishes a baseline for ensemble forecasting of cloud macrophysics. • This study established a baseline for ensemble forecasting of cloud macrophysical properties. • Ensemble mean provides more realistic results than each single scheme in most cases. • Height, intensity, and geometric thickness of convective clouds are shown to be over-estimated. • The COT bias attributes to underestimation of the cloud droplet effective radius and overestimation of the snow water path. [ABSTRACT FROM AUTHOR]

• Cloud seeding is found to be efficient on the increase of runoff or securing of additional water resources. • Various components of the hydrologic processes significantly increase by cloud seeding. • Increased rainfall highly contributes to the rainfall increase for both the event-based and annual analysis. • Wetter soil condition is more favorable to increase runoff and secure additional water resources. This study evaluates the effect of cloud seeding on the increase of runoff or securing of additional water resources. Unlike previous studies, this study concentrates more on the change of various components of the hydrologic processes. Both the event-based analysis and the annual analysis are conducted to evaluate the change of these components. The Boryeong Dam Basin in Korea is considered as a study basin. The WRF (Weather Research and Forecasting) model is used in the cloud seeding simulation, while the PRMS (Precipitation Runoff Modeling System) model is used in the rainfall–runoff analysis. The target years of this study are 2018 and 2019. As results, the event-based analysis shows that the infiltration, effective rainfall, interflow, and direct runoff are increased relatively more among the eight rainfall-runoff components considered in this study. In particular, the increase of interflow is noticeable. More than 60 % of the increased rainfall is found to contribute to the runoff increase. In the annual analysis, this ratio is found to become even higher. The ratio is estimated to be more than 90 %, which is mostly due to the contribution of baseflow. As important factors controlling the effectiveness of cloud seeding, the effects of antecedent soil moisture and threshold daily rainfall depth on the increase of total runoff are also evaluated. The results show that wet soil condition is more favorable to the successful cloud seeding experiment to secure additional water resources. Also, it is confirmed that the cloud seeding experiment can be more effective when the daily rainfall is more than 20 mm. Finally, the results of this study imply the efficiency of cloud seeding and its economic values are potentially high. [ABSTRACT FROM AUTHOR]

In the field of optimization computation, there has been a growing interest in applying intelligent algorithms to solve multi-objective optimization problems (MOPs). This paper focuses mainly on the multi-objective evolutionary algorithm based on decomposition, MOEA/D for short, which offers a practical general algorithmic framework of evolutionary multi-objective optimization, and has been achieved great success for a wide range of MOPs. Like most other algorithms, however, MOEA/D has its limitations, which are reflected in three aspects: the problem of balancing diversity and convergence, non-uniform distribution of the Pareto front (PF), and weak convergence of the algorithm. To alleviate these limitations, a new combination of the artificial raindrop algorithm (ARA) and a simulated binary crossover (SBX) operator is first integrated into the framework of MOEA/D to balance the convergence and diversity. Thus, our proposed approach is called MOEA/D with ARA and SBX (MOEA/D-ARA+SBX). On the other hand, the raindrop pool in ARA is further extended to an external elitist archive, which retains only non-dominated solutions and discards all others. In addition, the k -nearest neighbors approach is introduced to prune away redundant non-dominated solutions. In such a way, a Pareto approximate subset with good distribution to the true PF may be achieved. Based on the relevant mathematical theory and some assumptions, it is proven that MOEA/D-ARA+SBX can converge to the true PF with probability one. For performance evaluation and comparison purposes, the proposed approach was applied to 44 multi-objective test problems with all types of Pareto set shape, and compared with 16 other versions of MOEA/D. The experimental results indicate its advantages over other approaches. [ABSTRACT FROM AUTHOR]

Information is very limited on fate and transport of steroidal hormones in soils. In this study, the rainfall simulation tests were conducted with a soil slab reactor to investigate the transport of manure-borne testosterone in a silty-clay loam soil under six controllable operation conditions (i.e., three rainfall intensities and two tillage practices). The properties [e.g., rainwater volume, particle size distribution (PSD)] of the slurry samples collected in runoff and leachate at different time intervals were measured; their correlation with the distribution of testosterone among runoff, leachate and soil matrix was analyzed. The results indicated that more than 88% of the testosterone was held by the applied manure and/or soil matrix even under the rainfall intensity of 100-year return frequency. The runoff facilitated testosterone transport through both dissolved and particle-associated phases, with the corresponding mass ratio being ∼7 to 3. Soil particles collected through runoff were mainly silt-sized aggregates (STA) and clays, indicating the necessity of using partially-dispersed soil particles as testing materials to conduct batch tests (e.g., sorption/desorption). No testosterone was detected at the soil depth >20 cm or in the leachate samples, indicating that transport of testosterone through the soil is very slow when there is no preferential flow. Tillage practice could impede the transport of testosterone in runoff. For the first time, results and the methodologies of this study allow one to quantify the hormone distribution among runoff, leachate and soil matrix at the same time and to obtain a comprehensive picture of the F/T of manure-borne testosterone in soil-water environments. [ABSTRACT FROM AUTHOR]

A full-scale field test in the South-to-North Water Transfer Project (SNWTP) in China was conducted on a 60 m long expansive soil/rock channel slope reinforced with soilbags. The field test involved the construction of the soilbags, the rising and falling of the channel water level as well as the natural and artificial rainfalls. During the testing period, in-situ monitoring of water contents, earth pressures and lateral displacements was conducted. It was found that: 1) the water content of the expansive soil/rock slope changed slightly with the rainfalls and other environmental factors after the reinforcement with soilbags; 2) the earth pressure measured under the soilbags layer was close to its overburden pressure with no swelling pressure of the expansive soil contained in the bags; and 3) the lateral displacement of the expansive soil/rock channel slope mainly occurred before the construction of the soilbags layer and tended to be stable after the completion of the soilbags layer. The monitored results suggested the effectiveness of soilbags to prevent moisture migration, mitigate the swelling potential and enhance the slope stability. [ABSTRACT FROM AUTHOR]

Four runs (1, 2, 3, and 4) of physical analog model experiments, in which a square (ca. 60 × 60 cm) column of a mixture of fine sand and kaolinite is slowly raised at different rates (ca. 5.1, 1.3, 0.5, 0.2 mm/h, respectively) under artificial rainfall of about 38 mm/h, were conducted to observe how experimental landforms develop in relation to these uplift rates. As a square mound gradually emerges from ground level, fluvial erosion starts at the mound edges and develops into valley systems. This process of fluvial erosion, expressed in a linear relationship between relief (maximum height–minimum height) and mean cell slope (mean value of the highest slope gradient in a 1 cm × 1 cm grid cell), dominates until relief reaches about 60 mm, around the time when slope failures (slumps) start to dominate. If fluvial erosion dominates throughout the run ( relief stays below 60 mm), the uplift rate is considered to be below the lower threshold and landform development is in the “characteristic relief phase.” In all four runs, relief increases above 60 mm and slumps become significant as hills grow, indicating that uplift rates in this series are above the lower threshold. In run 1, the uplift at a high rate overwhelmed erosion and a massive mountain-like topography formed despite the occurrence of large slumps. The uplift rate in run 1 is thus above the upper threshold and landform development is in the “mountain building phase.” The mountain is likely to collapse when it grows higher than the limit of mountain growth determined by factors other than uplift rates. In runs 2, 3, and 4, after valley systems develop over the surface, hills grow with the occurrence of slumps and channel profiles seem to become stable at gradients corresponding to the uplift rates. As slopes grow steeper than a certain “critical gradient,” which is possibly the angle of repose of dry mound-forming material, they become vulnerable to slumps. However, slopes of material containing water and clay can grow steeper than this gradient in the absence of triggering events. The frequency distribution of cell slopes becomes bimodal, indicating the dominance of two types of slopes divided by the critical gradient, one below and another above. The former represents surfaces formed mainly by fluvial processes, and the latter surfaces formed by and/or waiting for slumps. Slumps reduce relief , but average height ( zmean ) does not fall unless sediments produced by slumps are carried away by fluvial processes. The combination of slope failure, fluvial processes, and uplift eventually works to keep z mean stable around a certain height depending on uplift rates, while relief repeats decrease and increase. The experimental landforms in runs 2, 3, and 4 seem to have achieved a certain steady state with uplift and erosion. The landform development in these runs is considered to be in the “steady-state phase,” with uplift rates between the lower and upper thresholds. These observations and interpretations are surprisingly consistent with studies on real landforms and can be of value in interpreting their development. [ABSTRACT FROM AUTHOR]

There are number of ways in which weak electrification can affect the microphysics of clouds, with consequences for cloud lifetime, radiative properties, and precipitation efficiency. Kauffman [2011] suggested ions produced by direct current generators will add to and enhance the catalysing effects that cosmic ray ions are now known to produce in among other things, lowering nucleation barriers, stimulating charged particle growth and stability and increasing the scavenging rate in clouds. Thus to electrify the atmosphere ions can be generated artificially in abundance along with large electric field. Ions can be generated by the corona effect using Atmospheric electrifiers (a device used to generate negative ions) which makes use of corona discharge phenomenon to charge the air particles. Exact assessment of electric field and charge density distributions and the flow dynamics inside the electrifiers is essential to understand the particle behaviour inside the electrifiers. In this paper, a novel model of governing equations to evaluate the space charge density, electric field intensity and velocity of ionized airflow is suggested as a function of applied voltage. The Poisson and charge conservation equations are derived and hence can be used to estimate the electric field and charge density distributions. Navier stokes equation can be used to get the velocity of ionized airflow because of electric force on the air. Simulation is carried out to validate the proposed model and verify that velocity is function of input voltage and is proportional to it. [ABSTRACT FROM AUTHOR]

The modest amount of rainfall in Israel occurs in winter storms that bring convective clouds from the Mediterranean Sea when the cold post frontal air interacts with its relatively warm surface. These clouds were seeded in the Israel-1 and Israel-2 cloud glaciogenic seeding experiments, which have shown statistically significant positive effect of added rainfall of at least 13% in northern Israel, whereas the Israel-3 experiment showed no added rainfall in the south. This was followed by operational seeding in the north since 1975. The lack of physical evidence for the causes of the positive effects in the north caused a lack of confidence in the statistical results and led to the Israel-4 randomized seeding experiment in northern Israel. This experiment started in the winter of 2013/14. The main difference from the previous experiments is the focus on the orographic clouds in the catchment of the Sea of Galilee. The decision to commence the experiment was partially based on evidence supporting the existence of seeding potential, which is reported here. Aircraft and satellite microphysical and dynamic measurements of the clouds document the critical roles of aerosols, especially sea spray, on cloud microstructure and precipitation forming processes. It was found that the convective clouds over sea and coastal areas are naturally seeded hygroscopically by sea spray and develop precipitation efficiently. The diminution of the large sea spray aerosols farther inland along with the increase in aerosol concentrations causes the clouds to develop precipitation more slowly. The short time available for the precipitation forming processes in super-cooled orographic clouds over the Golan Heights farthest inland represents the best glaciogenic seeding potential. [ABSTRACT FROM AUTHOR]

We investigated the influence of leaf traits, rainwater chemistry, and pedospheric nitrogen (N) fertilisation on the aqueous uptake of inorganic N by physiologically active tree leaves. Leaves of juvenile silver birch and European beech trees, supplied with NH 4 NO 3 to the soil at rates from 0 to 200 kg N ha − 1 y − 1 , were individually exposed to 100 μl of artificial rainwater containing 15 NH 4 + or 15 NO 3 − at two concentration levels for one hour. In the next vegetative period, the experiment was repeated with NH 4 + at the highest concentration only. The N form and the N concentration in the applied rainwater and, to a lesser extent, the pedospheric N treatment and the leaf traits affected the aqueous foliar N uptake. The foliar uptake of NH 4 + by birch increased when leaves were more wettable. High leaf N concentration and leaf mass per area enhanced the foliar N uptake, and NO 3 − uptake in particular, by birch. Variation in the foliar N uptake by the beech trees could not be explained by the leaf traits considered. In the first experiment, N fertilisation stimulated the foliar N uptake in both species, which was on average 1.42–1.78 times higher at the highest soil N dose than at the zero dose. However, data variability was high and the effect was not appreciable in the second experiment. Our data suggest that next to rainwater chemistry (N form and concentration) also forest N status could play a role in the partitioning of N entering the ecosystem through the soil and the canopy. Models of canopy uptake of aqueous N at the leaf level should take account of leaf traits such as wettability and N concentration. [ABSTRACT FROM AUTHOR]

This paper examines reflectivity data from three different radar systems, as well as airborne and ground-based in situ particle imaging data, to study the impact of ground-based glaciogenic seeding on shallow, lightly precipitating orographic cumuli, observed on 13 February 2012, as part of the AgI Seeding Cloud Impact Investigation (ASCII) experiment in Wyoming. Three silver iodide (AgI) generators were used, located on the windward slopes of the target mountain. This case was chosen for several reasons: the AgI generators were near the lifting condensation level, where the temperature was about -6 °C; cloud droplets were present in the cumulus clouds, which were rooted in the boundary layer; and the airflow, although weak, ascended over the mountain. The target mountain pass site was almost certainly impacted by seeding, according to a trace element analysis of the falling snow. Data from three radar systems were used in the analysis of the impact of seeding on precipitation: the airborne W-band (3 mm wavelength) profiling Wyoming Cloud Radar (WCR), two Ka-band (1.2 cm) profiling Micro-Rain Radars (MRR), and a X-band (3 cm) scanning Doppler-on-Wheels (DOW) radar. The WCR was onboard a research aircraft flying geographically fixed tracks, the DOW and one MRR were located at the target mountain pass, and another MRR was upstream of the AgI generators. Composite data from the three radar systems, each with their own target and upwind control regions, indicate that the observed changes in reflectivity profiles can be explained largely by the natural emergence of shallow cumuli. A comparison with lateral control regions (i.e., over the mountain, but to the side of the AgI plumes) suggests that seeding may have further enhanced snowfall, but the signal is weak. Particle probes at flight level and at the mountain pass site show that the concentration of small ice crystals (<1 mm) was significantly larger downwind of the AgI generators during seeding. This too is consistent with the emergence of shallow convection, but a comparison between flight sections downwind of the AgI point sources and those to the side suggests that glaciogenic seeding increased the concentration of ice crystals of all sizes in the shallow convection. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the commonly-held hypothesis that cloud seeding reduces precipitation in regions adjacent to seeding target areas, sometimes referred to as “downwind” but more correctly referred to as “extra area” effects (“the robbing Peter to pay Paul” hypothesis). The overall concept in the potential creation of extra area effects from seeding is illustrated with respect to the hydrologic cycle, which includes both dynamical and microphysical processes. For the first time, results were synthesized from five operational and research weather modification experiments, including winter orographic snowpack enhancement and summer experiments to enhance rainfall. One of the most surprising aspects of these results is that extra area seeding effects on precipitation appear to be uniformly positive (5–15% increases, perhaps greater for some convective systems) for both winter and summer seeding projects examined in this paper. The spatial extent of the positive extra area seeding effects may extend to a couple hundred kilometers for winter orographic seeding projects and summer convective seeding projects (such as North Dakota, Texas, Thailand). Both microphysical and dynamical effects of seeding appear to be contributors to these extra area effects. Future work needs to incorporate larger data sets from some of the larger more sustained projects with advanced cloud models and tracer experiments. [Copyright &y& Elsevier]

Highlights: [•] Assessed seed rain into non-forest regrowth on degraded tropical peatland, Indonesia. [•] Seed rain was dominated by wind-dispersed species. [•] The majority of animal-dispersed foreign seeds were found under trees. [•] Seed dispersal was mainly from within the degraded area rather than from outside sources. [•] Results suggest diversity of woody plants in recovering areas will remain limited. [Copyright &y& Elsevier]

Abstract: Free-roaming animals continually cope with changes in their environment. One of the most unpredictable environmental phenomena is weather. Being able to respond to weather appropriately is crucial as it can be a threat to survival. The stress response, consisting of increases in heart rate and release of glucocorticoids, is an important mechanism by which animals cope with stressors. This study examined behavioral, heart rate, and corticosterone responses of captive European starlings (Sturnus vulgaris) to two aspects of weather mimicked under controlled conditions, a subtle (3°C) decrease in temperature and a short, mild bout of rain. Both decreased temperature and exposure to rain elicited increases in heart rate and corticosterone in non-molting starlings. Molt is an important life history stage in birds that affects feather cover and may require a different response to weather-related stressors. We repeated the experiment in molting starlings and found increases in heart rate in response to rain and cold wind. However, the hypothalamic–pituitary–adrenal (HPA)-axis was suppressed during molt, as molting starlings did not increase corticosterone release in response to either stimulus. These data suggest these stimuli induce increased allostatic load in starlings, and that animals may adjust their response depending on the life-history stage. [Copyright &y& Elsevier]

Abstract: Raindrop axis ratio, falling velocity and size distribution are important in broad list of applications. However, they are not frequently observed in the equatorial region. This paper elucidated the characteristics of raindrop axis ratio, falling velocity and size distribution based on 2D-Video Disdrometer (2DVD) data that have been collected in the equatorial Indonesia, particularly at Kototabang (hereafter called KT), west Sumatra, Indonesia (0.20°S, 100.32°E, 864m above sea level). A comprehensive follow-up of the previous study on the natural variability of raindrop size distributions (DSDs) is presented. Precipitation was classified through 1.3-GHz wind profiler observation. The dependence of raindrop falling velocity and axis ratio on rainfall type was not clearly observed. Overall, measured raindrop fall velocities were in good agreement with Gunn–Kinzer''s data. Raindrop axis ratio at KT was more spherical than that of artificial rain and equilibrium model, and close to the values reported in the turbulent high shear zone of surface layer which can be partially due to the effect of the instrument errors (e.g., location and container shape). Of some natural variations of DSD investigated, the dependence of DSD on rainfall rate and rainfall type as well as diurnal variation was clearly visible. A striking contrast between the stratiform and convective rains is that the size distributions from the stratiform (convective) rains tend to narrow (broaden) with increasing rainfall rates. For rainfall rate R <10mm/h, the size distribution of stratiform was broader than that of convective. On the other hand, at higher rainfall rate more large-sized drops were found in convective rain. During the convective rain, very large-sized drops were found mainly at the very start of rain event while for the stratiform they were found to be associated with a strong bright band. In diurnal basis, the DSDs in the morning hours were narrower than those in the evening which was indicated by smaller D m values in the morning hours than their counterparts in the evening. Rainfall type dependence and diurnal variation of DSD lead to significant variation of Z–R relations so that they must be considered to increase the accuracy of Z–R conversion from weather radar in this region. Consistent with the previous study, lack of seasonal DSD variability was also found in this work that would be due to significant local convective and orographic effect at this region throughout the year. However, D m values in our result were larger than the typical orographic DSD. [Copyright &y& Elsevier]

Abstract: During four winters when cloud seeding took place, precipitation samples were collected at three stations in the catchment area of the Sea of Galilee (target stations) and in one station west of the seeding line (control station). Chemical analyses were carried out on more than 4000 rain samples in order to determine the major and trace metal compositions and enrichment factors of Ag (EF) with respect to Al, where Al is used as a tracer for natural dust. In addition, satellite images were analyzed to characterize the cloud phase and the temperature of the tops of the rain clouds using the EUMETSAT second generation geostationary satellite. Our results show that the seeding agent (AgI) arrives to the target stations, as indicated by significantly higher EF Ag values of Ag there compared to the control station. Furthermore, we found higher EF Ag values in precipitation samples from mixed-phase clouds compared to precipitation from warm or fully glaciated clouds. This difference was observed only at the target stations. Therefore, our results are consistent with the hypothesis that AgI contributes actively to precipitation formation processes in mixed-phase clouds, where ice content is controlled by ice nuclei (IN) concentration. This is in accordance with the conventional wisdom that AgI should be mostly active in such clouds, but not in clouds that are already naturally glaciated or in warm clouds, and it supports previous statistical studies which claimed that cloud seeding enhanced rainfall in Northern Israel. [Copyright &y& Elsevier]

Abstract: Severe and more persistent droughts in the arid regions such as the western US have increased the interest in cloud seeding programs or weather modification (WM) operations to increase precipitation. An anticipated increase in precipitation could augment annual and seasonal streamflow and reduce the impacts during dry periods. This paper evaluates hydrological impacts of WM operations in the North Platte River watershed, by utilizing a hydrologic model. The Variable Infiltration Capacity (VIC) land surface hydrological model is calibrated and validated for the periods of 1950–80 and 1981–2000 respectively, using daily meteorological forcing and monthly streamflow data. Two sets of WM scenarios are developed and forced into the VIC model to quantify the impacts of increased precipitation on streamflow. The first scenario is based on existing WM operations in the State of Wyoming. The second scenario hypothetically apply WM throughout the watershed to identify suitable regions for cloud seeding operations. For the first scenario, an increase of 0.3–1.5% in annual streamflow is observed from model simulations for a 1–5% increase in precipitation. Follow-on scenarios have identified the central-west and south-west regions of the watershed, which consist of a higher coverage of Evergreen Needleleaf Forest, to generate higher streamflow during WM operations. The north-east and north-west regions, which consist of a higher coverage of open shrublands and grasslands, are found to generate lower increases in streamflow during these operations. The observed annual precipitation is higher for central and southern regions when compared to northern regions of the watershed. It can be considered that the simulated changes in streamflow from different regions could also be attributed to variation in annual precipitation distribution within the watershed rather than solely based on cloud seeding operations. For the proposed WM programs or programs that are claimed effective based on precipitation augmentation, the hydrological impacts can be evaluated based on this analysis. [Copyright &y& Elsevier]

Abstract: New particle formation (NPF) events have been recognized as an important process contributing to the cloud condensation nuclei (CCN) formation. In this study, measurement of NPF and predicted number concentrations of CCN using κ-Köhler theory were analyzed to assess the contribution of NPF to possible CCN. The particle growth rates of NPF events were categorized to two types: sulfur-rich (condensation and neutralization of sulfuric acid dominating net growth rate) and sulfur-poor cases. The growth rates for the sulfur-poor events were about 80% larger than those of the sulfur-rich cases on average. NPF events increased the CCN number concentrations by 0.4–6 times in the megacity area of Beijing. The enhancement ratios (the ratio of CCN number concentrations when obvious particle growth ended to that when it started during NPF events) were high for large supersaturation (S). For example, it was about 30–50% higher under S = 0.86% than under S = 0.07%. The enhancement ratios exhibited similar seasonal variation as the growth rates with a larger value in summer than other seasons, which suggested that growth rate was a key factor in the conversion of NPF to possible CCN. The enhancement ratios were higher during the sulfur-poor NPF events with larger growth rates mainly contributed by organic species, indicating that organic species were the dominant chemical contributor in facilitating the conversion of newly formed particles to possible CCN in the Beijing Megacity. [Copyright &y& Elsevier]

Abstract: During a total of 11 months, cloud condensation nuclei (CCN at super-saturation S 0.5%) and condensation nuclei (CN) concentrations were measured in the urban background aerosol of Vienna, Austria. For several months, number size distributions between 13.22 nm and 929 nm were also measured with a scanning mobility particle spectrometer (SMPS). Activation ratios (i.e. CCN/CN ratios) were calculated and apparent activation diameters obtained by integrating the SMPS size distributions. Variations in all CCN parameters (concentration, activation ratio, apparent activation diameter) are quite large on timescales of days to weeks. Passages of fronts influenced CCN parameters. Concentrations decreased with the passage of a front. No significant differences were found for fronts from different sectors (for Vienna mainly north to west and south to east). CCN concentrations at 0.5% S ranged from 160 cm−3 to 3600 cm−3 with a campaign average of 820 cm−3. Activation ratios were quite low (0.02–0.47, average: 0.13) and comparable to activation ratios found in other polluted regions (e.g. ). Apparent activation diameters were found to be much larger (campaign average: 169 nm, range: (69–370) nm) than activation diameters for single-salt particles (around 50 nm depending on the salt). Contrary to CN concentrations, which are influenced by source patterns, CCN concentrations did not exhibit distinct diurnal patterns. Activation ratios showed diurnal variations counter-current to the variations of CN concentrations. [Copyright &y& Elsevier]

Abstract: ; hereafter LHA) (Levin, Z., Halfon, N., Alpert, P., 2010. Reassessment of rain experiments and operations in Israel including synoptic considerations. Atmos. Res. 97, 513–525. DOI:10.1016/j.atmosres.2010.06.011.), reanalyzed the results of the operational seeding in northern Israel between 1975 and 2007 and the preceding Israel 2 cloud seeding experiment (1969–1975) and concluded that there is no net increase in precipitation over the target areas. Our analysis revealed that a synoptic bias during Israel 2 is one of the reasons for the apparent positive effect of seeding in the northern target area and the negative effect in the southern area both of which disappeared in the following experiment in the south (Israel 3; 1975–1995) and the operational seeding in the north. ;hereafter BRG) criticized our paper primarily on the ground that we did not consider the positive results of Israel 1 experiment (1960–1967). It should be noted that in Israel 1 different seeding lines were used from those in both Israel 2 and the operational period. In addition, its raw data is not accessible anymore for reanalysis. Furthermore, Israel 2 had been designed as a confirmatory cross-over experiment to Israel 1 and failed to reproduce its promising results with double ratio (DR) of ~1.00, namely, zero rainfall enhancements. The same DR values were also found in Israel 3 and in the operational seeding. Therefore, because of the differences in the two experiments, the lack of access to the raw data and the disappointing results of the confirmatory experiment, we decided to concentrate our analysis on the more recent seeding activities. The attempt by BRG to explain the reduction of the DR to ~1.00 in the operational seeding period by the suppression due to pollution have been disproved by and also fail to explain the sharp decline of the target/control ratio right at the beginning of the operational seeding period when the lucky draw in this area came to its end (see LHA). [Copyright &y& Elsevier]

Abstract: By the use of GPS and CINDAR, the physical tests were made for the operation of weather modification in Guangxi on 16 February, 2008 and 21 January, 2010. The study shows that after the cloud seeding, microphysical changes in the supercooled clouds may lead to the mitigation of the basic reflectivity of radar in the supercooled layer of cloud, while the enhancement of the basic reflectivity on radar in the warm cloud and rain layer, and the reflectivity over the targeted regions was more quickly in reaching the maximum value than the non-operated clouds which are under the similar conditions, and lasting a more longer period. After the cloud seeding, the maximum of the changing rate of the echo reflectivity in warm region may be 100% or more. [Copyright &y& Elsevier]