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The $F_{10.7cm}$ radio flux and the Sunspot Number are the most widely used long-term indices of solar activity. They are strongly correlated, which led to the publication of many proxy relations allowing to convert one index onto the other. However, those existing proxies show significant disagreements, in particular at low solar activity. Our aim is to bring a global clarification of those many issues. We compute new polynomial regressions up to degree 4, in order to obtain a more accurate proxy. We also study the role of temporal averaging on the regression, and we investigate the issue of the all-quiet $F_{10.7}$ background flux. Finally, we check for any change in the $F_{10.7}$ -- sunspot number relation over the entire period 1947 -- 2015. We find that, with a $4^{th}$-degree polynomial, we obtain a more accurate proxy relation than all previous published ones, and we derive a formula giving standard errors. The relation is different for daily, monthly and yearly mean values, and it proves to be fully linear for raw non-averaged daily data. By a simple two-component model for daily values, we show how temporal averaging leads to non-linear proxy relations. We also show that the quiet-Sun $F_{10.7}$ background is not absolute and actually depends on the duration of the spotless periods. Finally, we find that the $F_{10.7cm}$ time series is inhomogeneous, with an abrupt 10.5% upward jump occurring between 1980 and 1981. Our new proxy relations show the importance of temporal scale for choosing the appropriate proxy and the $F_{10.7}$ quiet-Sun background level. From historical evidence, we conclude that the 1981 jump is most likely due to a unique change in the $F_{10.7}$ scientific team and the data processing, and that the newly re-calibrated sunspot number (version2) will probably provide the only possible reference to correct this inhomogeneity., 51 pages, 27 figures, 10 tables

City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind field over an urban lake that had once been built as a designated fresh air corridor for the city center of Münster, northwest, Germany. The model initialization was performed using the main wind direction and stable boundary layer conditions as input. The initial wind and temperature profiles included a weak nocturnal low-level jet. By emitting a passive scalar at one point on top of a bridge, the dispersion of fresh air could be traced over the lake’s surface, within street canyons leading to the city center and within the urban boundary layer above. The concept of city ventilation was confirmed in principle, but the air took a direct route from the shore of the lake to the city center above a former river bed and its adjoining streets rather than through the street canyons. According to the dispersion of the passive scalar, half of the city center was supplied with fresh air originating from the lake. PALM proved to be a useful tool to study fresh air corridors under stable boundary layer conditions., Finanziert durch den Open-Access-Publikationsfonds der Westfälischen Wilhelms-Universität Münster (WWU Münster).

For the investigation of geographical, monthly, seasonal, and annual distributions of aridity and its annual trend in the region of the Central and Southern Pannonian Basin (CSPB), which includes the territories of Hungary and Vojvodina (Northern Serbia), the De Martonne Aridity Index (DMAI) was used. The DMAI was originally calculated from a total of 78 meteorological stations with the maximum available time series of climatological data in three cases: 1931&ndash, 2017 for Hungary, 1949&ndash, 2017 for Vojvodina, and 1949&ndash, 2017 for Hungary and Vojvodina jointly. The Palmer Drought Severity Index (PDSI) was used to control the DMAI results. Temperature and precipitation trends were also investigated to understand their effects on the aridity trend. Three aridity types are distinguished on the annual level, five on the seasonal level, and four on the monthly level. The annual aridity had no trends in all three periods. It seems that aridity can be considered a more stable climate indicator of climate change than the temperature, at least in the CSPB.

Numerous extreme heatwaves producing large impacts on human health, agriculture, water resources, energy demand, regional economies, and forest ecosystems occurred during the first twenty years of the 21st century. The present study strives to provide a systematic review of recent studies of warm biometeorological extremes in Europe. The main aim of this paper is to provide a methodical summary of the observed changes in warm extremes, duration, and variability in different parts of Europe. During the last decade, much attention has been paid to the negative impacts of heat and humidity on human health. Therefore, the human biometeorology is required to appraise the human thermal environment in a way that human thermoregulation is taken into account. In many European countries and regions, future heat exposure will indeed exceed critical levels, and a steep increase in biometeorological heatwaves and warm extremes are expected. The indices that take into account human energy balance along with weather conditions should be used to examine the impacts of extreme heatwaves on human health and should be used as a basis for the determination of acclimatization to high-heat-stress conditions. A detailed description of recent studies that have used biometeorological indices such as Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) for the estimation of warm extremes and their influence on human health is provided. Additionally, a short overview of the existence of the heat-health warning systems (HHWS), their conceptualization, and implementation across the European continent is considered, as well as the possibilities for further investigations and implementation of effective measures and programs that could reduce the adverse health impacts.

Due to climate change, important attention was paid to the precipitations amounts over Moldavia's northern part. To point out the rainy air-circulation types was used the ‘Hess-Brezowsy’ Grosswetterlagen system (HBGWL) with 29 types of classifying European synoptic regimes of the 2000 to 2018 period at the reference weather stations of Bacău (184 m), Botoșani (161 m), Ceahlău-Toaca (1897 m), Iași (102 m), and Suceava (350 m). The highest amounts of precipitations annually from 2000 to 2018 in Romania's northeastern part were associated with the retrogressive cyclones. Therefore, on a background of the northeastern, cyclonic type (NEZ), there were recorded 53.45 mm, followed by High Scandinavia-Iceland, the ridge over Central Europe (HNFA), with 48.14 mm, and those from East in cyclonic type, with 44.03 mm. All the high over Central Europe (HM) weather types were associated with the lowest precipitations, only 1.71 mm. Also, small amounts of precipitations in the southwestern and south background, both of them into an anti-cyclonic type (SWA, SA), with 2.56 mm, respectively, 2.92 mm. Semestrial, the most important amounts of precipitations in the northeastern part of Romania were attributed to the retrogressive cyclones in the Eastern part of Romania and the ridges over the northern part of Europe. So, associated with EZ, during the 2000 to 2018 period, in the cold semester were recorded 28.43 mm and 27.66 mm within NEZ. During the warm semester, the highest amounts of precipitations were recorded within the HNFA type, with 42.75 mm, followed by Highs over the British Isles (HB) – 25.44 mm. The lowest values were associated with the southerly and southwesterly, both into an anti-cyclonic type (SA, SWA).

Determination of the fluctuations in groundwater level (GWL) in terms of planning and operating their resources is important. In Turkey, many basins are experiencing problems in terms of the potential of groundwater. Increasing water demand, adverse conditions created by climate change and lack of planning related to underground water management in the basin have increased these problems. As a field of application, it was applied for General Directorate of State Hydraulic Works (DSI) well of Hatay province in Turkey. In the study, GWL predictions were evaluated using data mining approaches such as Radial Basis Neural Network (RBNN) and Support Vector Machines (SVM) methods. Monthly data sets between 2002 and 2015, including hydrological parameters predict the GWL used. According to comparison results, it was observed that the data mining models gave good results for observation in test phase.

A large number of floodplains got lost due to settlements, infrastructure and agriculture. The reconnection of floodplains plays a significant role considering water retention potential and other aspects such as biodiversity conservation, improvement of water status and river morphology. The delineation and evaluation of potential floodplains and their reconnection capacity require the consideration of the multiple parameters to characterize the effectiveness of floodplains in terms of hydrology/hydraulics, ecology and sociology. In order to delineate floodable area within the lower part of the Desnatui river an unsteady 1D hydrodynamic model has been built up and calibrated, using HEC-RAS software. The Floodplain Evaluation Matrix tool has been applied taking into account the following categories of parameters: hydrology (peak reduction ΔQ, flood wave translation Δt), hydraulics (water level Δh), ecology (connectivity of floodplain water bodies, existence of protected species) and socio-economics (potentially affected buildings, land use). The results showed that identified floodplain areas have high demand for restoration.

Blizzard phenomena is a complex atmospheric event, in which the snow that falls or has fallen is blown away by the wind, so that the visibility decrease significant enough and the assessment of the simultaneous snow fall is impossible (Țîșlea, D. et al. 1965). The region of Oltenia is featured by a climate with Mediterranean influences, with the dominance of northwest and east winds (Roșu, Al. Et al. 1971). The contact between the cold and the warm air masses leads to the increase of the horizontal baric gradient, which causes strong wind intensification. Due to the geographical position of the Carpathian chain, the penetration of colder and denser air is directed towards the east and the south of Romania, thereby has an impact on the study area (***Climate of Romania 2008). Out of all the natural phenomena during the cold season, blizzard is by far the most versatile, with a heavily impact on society and environment (Teodoreanu 2004). The purpose of this paper is to emphasize the hydro meteorological outcome of the 2018 blizzard episode from February 24#$ to March 2%&. In order to achieve this, we will identify the spatial and temporal variability of the hazard in the region of Oltenia, the atmospheric mechanism of this late blizzard occurrence, its climatic characteristics and the consequences on the rivers runoff regime. We will analyze the synoptic conditions under which the blizzard appeared, the recorded meteorological data and a series of hydrological data from the stations located on the main rivers (Jiu, Olt and Danube) in order to determine the synoptic weather pattern, the successive number of days with blizzard, the dominant direction and the average and maximum wind speed, the average and maximum amount of precipitation, as well as for the thickness of snow layer and the daily liquid levels and flows.

The study aims to analyze and compare the mean sea level pressure field to show the changes in the breeze regime in the coastal area of Romania in the current climate and the one projected in climate scenarios. The mechanism and variability of the breeze cell (intensity, location, frequency, persistence) are analyzed and compared for extreme conditions of warmest summers (July) during the two climatic intervals: 1971- 2000 respectively for the RCP4.5 2021-2050 scenario. The high-resolution climate is simulated using the RegCMv4.5 regional climate model at 5 km resolution, coupled with the global EC-Earth model. These dynamical downscaling methods were performed for the first time for Romania in ANM (Meteo Romania) during the AZURE-Microsoft project (2018), aiming to refine the scale of the global climate scenarios to allow process analysis. The mechanism of changes is analyzed with the interaction between regional-scale conditions and large-scale dynamic factors. The results indicate changes in the frequency of intense events and the spatial development of the breeze cell, with a time-mean intensification of both sea and land breezes and, a greater spatial advance in the area mainly during the day. Large scale-dynamics changes in interaction with the breeze circulation lead to an anticyclonic rotation under a warmer climate of the coupled circulation that induces a shift to the South-West of the cell, with a possible impact on the location of the associated precipitation. Regarding timing, a time-delay in the sea breeze occurrence (smaller pressure gradients persist longer due to warmer sea surface temperature), together with enhanced cell intensity, later on, makes the event appear as a more abrupt or extreme one. The results of the study provide potentially important input for further analysis of projected impacts of the breeze circulation on the regional climate.

The study presents the results of the measurement realized at a meteorological weather station installed in Cârja village, situated in the valley of Prut river in the south-eastern tip of Vaslui county, Romania. The observations cover the interval from 2013 and 2020 and bring valuable data upon a region that lacks an official weather station. We present briefly the climatic profile of the weather station as reflected by the main climate elements (air pressure, air temperature, relative humidity, precipitation and wind) and a brief comparison with the data extracted from ROCADA database for the weather station location during the common period (January – December 2013). As main climate features, we underline the mean air temperature of 12.0 °C and the annual precipitation amount of 477.5 mm. It is worth noticing that the difference between the in situ observations and the ROCADA database is below 1°C, being higher in summer time. Additionally, some details are given on those climatic parameters that present practical importance, such as rain intensity or wind power potential. The main conclusions of the study consists in (1) highlighting the very warm conditions specific for the last decade in the analysis region and (2) the relatively high agreement observed between in situ observations and the ROCADA database.

The first part of the study analyzes the precipitations recorded in June over the 1961-2020 period for 22 climatological weather stations over different regions of Romania in order to determine if precipitations in June 2020 were higher than those recorded before 2020. For this, 5 precipitation indices have been used: number of heavy and very heavy precipitation days, 24-, 48- and 72-hours precipitation amounts. The second part is dedicated to precipitations recorded in June 2020, registered at 157 weather stations from Romania, divided in historical regions; it analyzes the number of heavy and very heavy precipitation days, synoptic and mesoscale conditions from different periods of time using the specific methods of investigation (charts of sea level pressure, geopotential height, temperature and humidity, atmospheric soundings, different stability indices, vertical wind shear, infrared and visible satellite images and radar images of convective storms). The main findings are: precipitations recorded in June 2020 at 22 climatological weather stations did not exceed the absolute maximum precipitation recorded between 1961-2019, and precipitations recorded in 24, 48 and 72 hours were higher only at 2 or 3 weather stations; the number of heavy and very heavy precipitation days recorded in June 2020 were higher in the Carpathians, the North and Center, and the West regions of Romania; synoptic conditions were determined by low values of atmospheric pressure at the surface and/or by the atmospheric depressions, while in the middle troposphere, an atmospheric trough or a cut-off low was present; mesoscale conditions presented low or medium values of Convective Available Potential Energy, negative values of Lifted Index, and weak or medium wind shear in the 0-3 km layer.

The paper presents and analyzes the variations of meteorological and specific snow parameters which favored the onset of avalanches in the winter season 2019-2020 in the mountains monitored by the Snow and Avalanche Program of the National Meteorological Administration, taking also into account the estimated avalanche risks for each massif. The analyzed parameters are those measured during the daily observations and weekly measurements at the meteorological stations Bâlea-Lac, Vârful Omu, Sinaia, Predeal, Parâng, Țarcu, Semenic, Vlădeasa, Iezer, Călimani, Ceahlău, as well as during some measurement campaigns outside the meteorological stations area. Avalanche cases and favorable conditions for their triggering are included in a database, to be analyzed and used to better estimate the avalanche risk and reduce their effects on the environment and people. The favorable conditions for triggering the avalanches were due to both significant snowfall, high temperature values or their sudden increase, as well as the transformations that take place inside the snow layer, as a result of which unstable structures are formed.

In the recent decades, droughts and dry episodes throughout a year have become common for both arid and humid regions. The Carpathian Mountains referred to as natural water towers are also the case. Accordingly, the study aims and distinguishing monthly and daily patterns and peculiarities of precipitation shortage in the high-mountain areas (above 1000 m) of the Polish and the Ukrainian Carpathians using monthly and daily data series (1984-2015) of weather stations Kasprowy Wierch (1991 m a.s.l), Dolina Pięciu Stawów (1670 m a.s.l) and Morskie Oko (1408 m a.s.l) in the Polish Carpathians, Play (1343 m a.s.l) and Pogegevskaya (1429 m a.s.l) in the Ukrainian Carpathians. Here, in all the months throughout a year, dry episodes have been detected. In the Polish Carpathians, represented by three measuring stations, the driest episodes in the years took place from August to October and January, and slightly less – about 11-16% in the remaining months. In the monthly context, the highest frequency of dry months, exceeding 20%, is detected in June both in Pogegevskaya, as well and in April and July in Play. In March, April, as well as November extreme atmospheric drought took place in the entire area of the Polish Tatra Mountains, the highest mountain range of the Polish Carpathians. In all the measuring stations of the area in November 2011, the precipitation amount did not exceed 11 mm. They accounted for less than 10% of the average multiannual precipitation sum. Alongside, the positive trend in the years from 1984 to 2015 with significance levels of 0.1 and 0.2 was only established in the lowest monthly precipitation sums at Pogegevskaya. The longest episodes without precipitation, periods that begin and end with a day without precipitation, are detected in most parts of the study area in October and November 2011, especially in the western and southern parts of the Polish Carpathians.

Large dams, as well as conventional hydrotechnical constructions with the role of breaking the drainage slope (waterfalls or bottom sills), flood mitigation or with the role of protection against floods (shore defences) have a profound impact on the environment. Due to these constructions, the ecosystems on the Bistrița Ardeleană river have undergone changes or even established new ones. This paper wants to highlight the morphological changes of the Bistriţa riverbed by analysing the transversal profiles made between 1972 and 2015. The profiles were made in the flow measurement section at two hydrometric stations, one being located in the upstream part of the river basin and the other before the Bistrița river flows into the Șieu river. By comparing the results obtained from the profiles made before the Colibița hydrotechnical system was started or completed with the data obtained from the profiles after the commissioning of the Colibița hydropower plant, we managed to highlight that the Bistrița Ardeleană riverbed registered several negative effects in terms of morphologically both vertically and horizontally. We also found that the riverbed downstream of the dam there is a phenomenon called hydraulic paving.

In ascertaining the performance of a high-resolution gridded forecast against an analysis, called the verification set, on the same grid, care must be taken to account for the over-accumulation of small-scale errors and double penalties. It is also useful to consider both location errors and intensity errors. In the last 2 decades, many new methods have been proposed for analyzing these kinds of verification sets. Many of these new methods involve fairly complicated strategies that do not naturally summarize forecast performance succinctly. This paper presents two new spatial-alignment performance measures, G and Gβ. The former is applied without any requirement for user decisions, while the latter has a single user-chosen parameter, β, that takes on a value from zero to one, where one corresponds to a perfect match and zero corresponds to the user's notion of a worst case. Unlike any previously proposed distance-based measure, both handle the often-encountered case in which all values in one or both of the verification set are zero. Moreover, its value is consistent if only a few grid points are nonzero.

Globally, mountains are often characterized as fragile and hazardous terrains, with vast areas covered by the cryosphere. The livelihoods of communities in the Hindu Kush Himalayan region are closely linked with the cryosphere. But over the past few decades, communities in the region have experienced multiple changes, including those driven by climat e change, with direct and immediate impacts on their lives and livelihoods. In this study, we explore linkages between the cryosphere and high-mountain livelihoods using a social‒ecological system approach. It examines how the complex social‒ecological system in villages in Langtang Valley, Nepal, has evolved in response to both cryospheric and socioeconomic changes. The local communities perceive gradual but significant changes in the cryospheric system, such as receding and thinning glaciers, changing snowfall patterns, changes in temperature and precipitation patterns, and a growing incidence of cryosphere-related hazards, such as avalanches and landslides. Communities in the Langtang Valley are also facing a number of socioeconomic changes, resulting in changing aspirations, particularly among the youth. The growing disconnection between society and the surrounding cryosphere, with direct impacts on the transfer and growth of local knowledge systems, are discussed. These simultaneous changes in the cryosphere and the socioeconomic domain have also resulted in a homogenization of livelihood sources, with tourism emerging as the dominant source of livelihood. This has resulted in a dependence of the local population on food imported from outside the valley. A growing dependence on tourism for livelihoods, dependence on imports for food and other basic needs, and the lack of a risk reduction strategy might pose great risks for local lives and livelihoods in the long run. Interventions pertaining to diversifying livelihoods, harmonizing social capital, and hazard risk assessment are essential for strengthening linkages between cryosphere and the socioeconomic system.

Understanding Pakistan's greenhouse gas (GHG) emission status is critical for identifying the national targets for GHG mitigation with respect to the nationally determined contributions (NDCs). This study focuses on the development of Pakistan's GHG (CO2, CH4, and N2O) inventories for agriculture, forestry and other land use (AFOLU) and waste sectors using 2006 IPCC Guidelines. This study should be seen as a direct continuation of the preceding one (Part I [ Available online at: https://doi.org/10.1016/j.accre.2020.05.002 ]) which discusses energy and industrial processes and product use in compliance with the 2006 and 1996 IPCC Guidelines. It also provides sector-specific comparative time series (1994–2017) analysis of GHG inventories, identification of key categories, and national GHG emissions trend for Pakistan. The results indicate an average relative difference (on average for time series 1994–2017) of 19% and 6% in total GHG emissions (CO2-eq) from AFOLU and waste sector respectively between 2006 and 1996 IPCC Guidelines. The absolute difference over the entire time series for AFOLU and waste sector was in the range of 3–67 Mt CO2-eq and 1–7 Mt CO2-eq respectively. Findings further reveal that the quantity of national GHG emissions by 2006 IPCC Guidelines is 10% lower on average for complete time series compared to 1996 IPCC Guidelines. The average relative difference for total national emissions of CO2, CH4 and N2O is −1%, 9%, and 48% respectively. Key category analysis based on 2006 IPCC Guidelines estimates identified three categories, each contributing ≥10% to the level assessment in the latest year 2017 and accounting for approximately half of the national GHG emissions. In order to further improve the reliability of GHG inventories, Pakistan needs to move from 1996 to 2006 IPCC Guidelines under a higher Tier approach particularly for identified key categories.

Permafrost in Northeast China is highly sensitive to climate warming. Permafrost degradation significantly affects forest and vegetation ecosystems, as well as the safety of engineering projects and other man-made infrastructures. However, the permafrost change in the region is still unclear. This study uses metrological data from 258 weather stations, alongside reanalysis data, and other environmental data to investigate permafrost degradation and its related environmental impacts in Northeast China from the 1950s to 2010s. Results show that the total permafrost area decreased from 4.8 × 105 to 3.1 × 105 km2 from the 1950s to the 2010s. The southern limit of permafrost moved 0.1–1.1° northward, and its average elevation rose 160.5 m. During the study period, the degradation of predominantly continuous permafrost, and discontinuous and island permafrost was more pronounced than that of sparsely island permafrost. The south boundary of those three permafrost zones northward by 0–3.4°, 0‒5.5° and 0.4–1.1°, the average altitude raised by 339.2 m, 208.3 m, 67.1 m. The permafrost degradation shows the elevation and latitude zonality. Permafrost degradation is mainly caused by the rising of surface temperatures and the impacts of other environmental factors. The snowfall warming the ground of 1.1–10.2 °C in cold seasons and rainfall cooling on surface conditions in warm seasons, those may result in temporal and spatial differences in permafrost degradation. However, there are lack of researches in the impact of environment factors on soil temperatures, moisture and permafrost degradation.

Snow properties and their changes are crucial to better understanding of hydrological processes, soil thermal regimes, and surface energy balances. Reliable data and information on snow depth and snow water equivalent (SWE) are also crucial for water resource assessments and socio-economic development at local and regional scales. However, these data are extremely limited and unreliable in northern Xinjiang, China. This study thus aims to investigate spatial variations of snow depth, SWE, and snow density based on winter snowfield surveys during 2015 through 2017 in the Altai Mountains, northwestern China. The results indicated that snow depth (25–114 cm) and SWE (40–290 mm) were greater in the alpine Kanas-Hemu region, and shallow snow accumulated (9–42 cm for snow depth, 26–106 mm for SWE) on the piedmont sloping plain. While there was no remarkable regional difference in the distribution of snow density. Snow property distributions were strongly controlled by topography and vegetation. Elevation and latitude were the most important factors affecting snow depth and SWE, while snow density was strongly affected by longitude across the Altai Mountains in China. The influence of topography on snow property distributions was spatially heterogenous. Mean snow depth increased from 13.7 to 31.2 cm and SWE from 28.5 to 79.9 mm, respectively, with elevation increased from 400 to 1000 m a.s.l. on the piedmont sloping plain. Snow depth decreased to about 15.1 cm and SWE to about 28.5 mm from 1000 to 1800 m a.s.l., then again increased to about 98.1 cm and 271.7 mm on peaks (∼2000 m a.s.l.) in the alpine Kanas-Hemu. Leeward slopes were easier to accumulate snow cover, especially on north-, east-, and southeast-facing slopes. Canopy interception was also the cause of the difference in snow distribution. Snow depth, SWE, and snow density in forests were reduced by 8%–53%, 2%–67% and −4% to +48%, respectively, compared with surrounding open areas. Especially when snow depth was less than 40 cm, snow depth and SWE differences in forests were more exaggerated. This study provides a basic data set of spatial distributions and variations of snow depth, SWE and snow density in the Altai Mountains, which can be used as an input parameter in climate or hydrological models. These first-hand observations will help to better understand the relationship between snow, topography and climate in mountainous regions across northern China and other high-mountain Asian regions.

Permafrost presents extensively on the land surface and it is degrading under the combined influences of warming climate and human activities. The degrading permafrost will post profound impacts in hydrology, ecology, engineered infrastructures, and socioeconomic development. In order to better adapt to these changing permafrost environments, we need to better understand permafrost degradation and its impacts, as well as to timely develop predicting capabilities and adaptive strategies and mitigative measures. However, due to the remoteness of permafrost regions, low density of population and observational networks, and paucity of measured data, our understanding on degrading permafrost and its various impacts is still limited. This Special Issue of Degrading Permafrost and Its Impacts, as a proceed of the forthcoming 12 th International Conference on Permafrost, collects seven papers on permafrost environments and engineering in a timely manner, in order to reflect the latest progress in this chosen topic. This Special Issue on Degrading Permafrost aims at facilitating the studies on the adaptive and sustainable development of the permafrost environment and human society under a warming climate.

Accurate and reliable solid precipitation estimates for high mountain regions are crucial for many research applications. Yet, measuring snowfall at high elevation remains a major challenge. In consequence, observational coverage is typically sparse, and the validation of spatially distributed precipitation products is complicated. This study presents a novel approach using reliable daily snow water equivalent (SWE) estimates by a cosmic ray sensor on two Swiss glacier sites to assess the performance of various gridded precipitation products. The ground observations are available during two and four winter seasons. The performance of three readily-available precipitation data products based on different data sources (gauge-based, remotely-sensed, and re-analysed) is assessed in terms of their accuracy compared to the ground reference. Furthermore, we include a data set, which corresponds to the remotely-sensed product with a local adjustment to independent SWE measurements. We find a large bias of all precipitation products at a monthly and seasonal resolution, which also shows a seasonal trend. Moreover, the performance of the precipitation products largely depends on in situ wind direction during snowfall events. The varying performance of the three precipitation products can be partly explained with their compilation background and underlying data basis.

Climate change and ozone depletion are topics challenging the world over and are both attributed mainly to human activities, particularly emissions of ozone depleting substances. One such substance is chlorodifluoromethane (HCFC-22), a cheap, widely used refrigerant with a high global warming potential and a chemical target for phase-out under the Montreal protocol. Botswana like all signatory countries to the Montreal Protocol is required to develop and implement a country-level Hydrochlorofluorocarbon Phase-out Management Plan (HPMP). This study focused on evaluating the environmental and socioeconomic implications of phasing out HCFC-22 in Botswana. A census of nine HCFC-22-importing companies was conducted and probability sampling proportional to company size was used to select a sample of 159 respondents from the Department of Meteorological Services, Customs officers and HCFC-22 Industrial consumers. Annual HCFC-22 importation figures for Botswana in 2009–2017 from the National Ozone Unit were analysed. It emerged that HCFC-22 phase-out had reduced HCFC-22 consumption by approximately 510,400 kg in 2011–2017, translating to 28,072 ozone depleting potential (ODP) saved. Also, the HCFC-22 phase-out plan saved the country 128 kW h of electricity for 2009–2017. While decreasing demand for HCFC-22, the HPMP had correspondingly occasioned the higher replacement and servicing costs of HCFC-22-compliant equipment, as HCFC-22 substitutes cost more. To deter use of HCFC-22 and promote phase-out, the price of substitute refrigerants can be made less expensive than HCFC-22. Participating stakeholders attest that HCFC-22 phase-out has positive social benefits such as raising community awareness of the ozone depleting phase-out. As a recommendation, the government of Botswana could offer a number of incentives towards HCFC-22 substitutes uptake in order to give impetus to technology transfer.

The embankment of the Qinghai–Tibet Railway (QTR) has been experiencing severe problems due to permafrost degradation, especially in warm and ice-rich permafrost regions. Based on ground temperature and deformation data of the embankment at location K1497 + 150 of the QTR in 2006–2018, the thermal regime and deformation process were analysed. The results showed that 1) the degradation rate of permafrost under the embankment was faster than that under the natural site without engineering construction, and 2) the deformation rate of the embankment had exceeded the safety range for the QTR embankment before adopting mitigative measures. In addition, this study evaluated the cooling effect on the underlying permafrost and working mechanism of two strengthening measures. Two measures, crushed rock revetment (CRR) and thermosyphons, were adopted to protect the underlying permafrost from continual degradation. The individual cooling effect of the CRR was not as good as that of the thermosyphons. However, the combination of the two could enhance the protective effects of each on the underlying permafrost, effectively cooling the permafrost and improving the stability of the embankment.

The shear behavior of the frozen soil−structure interface is important for accurately predicting the interface responses of structures adopted in the cold regions. The purpose of this study is to experimentally and theoretically investigate the shear behavior of frozen clay–concrete interface under engineering conditions. A large-scale direct shear apparatus with a temperature-controlled shear box is used to test the interface behavior. Test specimens consisting of a cement concrete block and frozen soil with initial water content ranging between 14.6% and 24.6% were prepared at different conditions of temperatures (15.4 to −9.8 °C), shear rates (0.03–0.9 mm min−1), and normal stresses (50–200 kPa). It is found that the peak shear strength is linear developing with increasing of normal stress, initial water content, and temperature. It increased from 67.7 to 133.3 kPa as the initial water content increased from 14.9% to 24.6% at temperature of −6.8 to −6.6 °C, and it increased from 51.2 to 80.6 kPa with temperature decreasing from 15.4 to −9.8 °C at initial water content of 14.6%–14.9%, furthermore it has a power law relationship with shear rate. The final vertical displacement increases with the decreasing temperature, and increasing initial water content. While, it is slight or could be ignored at lower shear rates (e.g. 0.03 mm min−1 and 0.15 mm min−1) and it is −0.25 mm and −0.28 mm at shear rate of 0.3 mm min−1 and 0.9 mm min−1, respectively. In addition, the evolution of vertical displacement also varies with test condition, the growth rate at beginning increases with increasing initial water content and decreasing temperature or ice content, which is because of the ice film effects the particle size. Moreover, a disturbed state concept model combined with linear and nonlinear characteristics is developed to describe the interface shear behavior. The disturbance D reflects the interface mechanical response and responds differently trend for different test conditions, increasing faster with increasing temperature and decreasing initial water content or shear rate. The testing results, including the test and model results, can be used to simulate the performance of engineered geotechnical assets such as earth dams or irrigation channels with concrete linings in cold regions.

In boreal and arctic regions, forest fires exert great influences on biogeochemical processes, hydrothermal dynamics of the active layer and near-surface permafrost, and subsequent nutrient cycles. In this article, the studies on impacts of forest fires on the permafrost environment are reviewed. These studies indicate that forest fires could result in an irreversible degradation of permafrost, successions of boreal forests, rapid losses of soil carbon stock, and increased hazardous periglacial landforms. After forest fires, soil temperatures rise; active layer thickens; the release of soil carbon and nitrogen enhances, and; vegetation changes from coniferous forests to broad-leaved forests, shrublands or grasslands. It may take decades or even centuries for the fire-disturbed ecosystems and permafrost environment to return to pre-fire conditions, if ever possible. In boreal forest, the thickness of organic layer has a key influence on changes in permafrost and vegetation. In addition, climate warming, change of vegetation, shortening of fire return intervals, and extent of fire range and increasing of fire severity may all modify the change trajectory of the fire-impacted permafrost environment. However, the observations and research on the relationships and interactive mechanisms among the forest fires, vegetation, carbon cycle and permafrost under a changing climate are still inadequate for a systematic impact evaluation. Using the chronosequence approach of evaluating the temporal changes by measuring changes in the permafrost environment at different stages at various sites (possibly representing varied stages of permafrost degradation and modes), multi-source data assimilation and model predictions and simulations should be integrated with the results from long- and short-term field investigations, geophysical investigations and airborne surveys, laboratory testing and remote sensing. Future studies may enable quantitatively assess and predict the feed-back relationship and influence mechanism among organic layer, permafrost and active layer processes, vegetation and soil carbon under a warming climate at desired spatial and temporal scales. The irreversible changes in the boreal and artic forest ecosystem and their ecological and hydrothermal thresholds, such as those induced by forest fires, should be better and systematically studied.

Under a warming climate, degrading permafrost profoundly and extensively affects arctic and alpine ecology. However, most existing relevant studies are more focused on the hydrothermal impacts of vegetation on the underlying permafrost, or symbiosis between vegetation and permafrost, only very few on ecological impacts of permafrost degradation. Additionally, there are much more pertinent investigations in arctic and boreal regions than those in alpine and high-plateau regions at mid- and low latitudes. This study emphasizes on the impact mechanisms of permafrost degradation on vegetation both at high and mid-to low latitudes, addressing vegetation succession trajectories and associated changes in soil hydrology and soil nutrient above degrading permafrost. Permafrost degradation influences vegetation by altering soil hydrology, soil biogeochemical processes and microbial communities, which further improve soil nutrient availability. Furthermore, under a warming climate, vegetation may take two successional trajectories, towards a wetter or drier ecosystem within a certain time period, but to a drier ecosystem in the end upon the thaw of permafrost in case of permeable soils and good drainage. Thus, with rapidly developing remote-sensing and other space- and ground-based and air-borne observational networks and numerical predictive models, the impacting mechanisms of permafrost degradation on vegetation should be timely and better monitored, evaluated and modeled at desired spatiotemporal scales and resolutions by terrestrial or integrated ecosystem models.

Dynamics of the frozen ground are key to understand the changes of eco-environment in cold regions, especially for areas with limited field observations. In this study, we analyzed the spatial and temporal variations of the ground surface freezing and thawing indices from 1900 to 2017 for the upper Brahmaputra River (also called the Yarlung Zangbo River in China) Basin (UBRB), southwestern Tibetan Plateau, with the air freezing and thawing indices using the University of Delaware (UDEL) monthly gridded air temperature dataset. The abrupt change years for air freezing index (AFI) and ground surface freezing index (GFI) were detected in 1999 and 2002, respectively, and for both air thawing index (ATI) and ground surface thawing index (GTI) were 2009. With the air temperature rising at a rate of 0.006 °C per year over 1900–2017, the AFI and GFI decreased at a rate of −0.1 °C d per year, while the ATI and GTI increased at rates of 0.3 and 0.5 °C d per year before the abrupt change year, respectively; all changing trends of freezing/thawing indices increased after the abrupt year, which was −2.9, −0.8, 7.3, and 21.7 °C d per year for the AFI, GFI, ATI, and GTI, respectively. We utilized the surface frost number model to obtain the dynamics of the frozen ground over the UBRB. When the empirical coefficient of E was assigned to 1.2, the simulated frozen ground occupied about 53.2% of the whole UBRB in the 1990s, which agreed well with the existing permafrost map published in 1996. The area of frozen ground accounts for 51.5%–54.5% of the UBRB during 1900–2017. This result may facilitate further studies of the multi-interactions among the frozen ground and relevant eco-environment, such as the air-ground surface energy exchange, hydrological cycles, and changes of the active layer thickness over the UBRB.

In permafrost regions of the Qinghai-Tibet Plateau, road disaster caused by permafrost degradation cannot be ignored. As a common thermal disaster in permafrost regions, thermokarst lake has serious thermal erosion on permafrost and results in permafrost degradation aggravating. This study focused on two subgrade cross-sections of Gonghe-Yushu Highway in the Qinghai-Tibet Plateau to analyze thermal effect of thermokarst lake on the permafrost under embankment. The analysis infers that thermokarst lake can transfer heat to permafrost under the embankment, as a heat resource, and the heat flux decreases with the distance away from thermokarst lake in horizontal and vertical direction. Thermokarst lake can cause average ground temperature of permafrost under the embankment increasing, and with less distance from the thermokarst lake the temperature increases more severely. Thermokarst lake results in 14 m thickness melting interlayer in soil under lake and change shape of melting area.

Hurricanes are destructive forces of nature that have the ability to cause vast devastation both economically and socially. Estimating the potential damage caused by hurricanes aids local, state and federal governments as well as insurance and reinsurance companies to plan for future hurricanes. Direct damages caused by hurricanes are difficult to estimate. There are multiple factors that could contribute to the damages caused by a hurricane. Wind is typically considered the most important factor to account for when estimating potential damage. Aside from the complex physical processes, the difficultly in estimating hurricane damages is further compounded by limited data and a changing climate. Fitting models with limited data presents a series of challenges. These challenges include outliers that could form a large proportion of the data, overfitting, missing data and it becomes difficult to leave out a portion of the data for external validation. This study found a significant positive correlation using the Kendall rank correlation coefficient between hurricane damages, measured by the area of total destruction and the maximum landfalling wind speed (τ = 0.451). A copula-based approach was used to model their dependency. Both bivariate Archimedean and elliptical copulae families were assessed as potential models. A bivariate Frank copula with Weibull marginals was found to be the most appropriate fitting model based on a visual inspection of the contour plots of the fitted copulae. Simulation from the fitted copula was qualitatively similar to observation. This study demonstrated a potential method to overcome the limitation of small data facing models to estimate hurricane damages.

This paper highlights the results of adaptation and verification of the Delft3D Flexible Mesh numerical model under the conditions of the Sasyk reservoir. The objective of this work is to evaluate the expected spatio-temporal variability of water salinity in the Sasyk reservoir after completion of the Sasyk renaturalization project by means of establishing a constant water exchange with the sea through the artificial channel. The Sasyk Lagoon was separated from the sea and transformed into a freshwater reservoir in the late 1970s. However, due to the poor water quality in the Sasyk reservoir in the modern period, the solution of the problem of transforming the reservoir to its original coastal conditions, i.e. the renaturalization, has acquired particular importance. Model results, obtained under conditions of 2019, indicate the possibility of using a hydrodynamic model to evaluate the effectiveness and possible consequences of various scenario-based decisions to be implemented for the management of the hydrological regime of the reservoir under various options of its operation. The model runs were used to evaluate the flushing time of the Sasyk Lagoon and the pattern of the salinity fluctuations in the reservoir after the restoration of the artificial channel in the sand bar with a width of 100 m and a depth of 1.5 m and the establishment of the constant “sea-lagoon” interconnection. Applying the hydrometeorological conditions of 2019, a scenario-based modelling for two consecutive years was performed. For the first year of the simulation, a variant of water management under the absence of freshwater inflow from the Danube and the presence of sea water inflow throughout the year was considered. The model results at the end of the first year of the simulation were set as the initial conditions for the second year, and the rest of the external forcing remained unchanged. Additionally, the variant considering the Danube discharge into the lagoon during May-July for the second year of simulation was investigated. Based on the simulation results, it was found that in the case of a constant water exchange with the sea through the connecting “sea-lagoon” channel (with the abovementioned morphometric characteristics) and under the absence of the Danube freshwater inflow throughout the year: 1) the flushing time of the lagoon will be 1 year and 5 months; 2) stabilization of water salinity in the lagoon will not occur, i.e. the salinization of the lagoon water takes place in the long-term perspective; 3) the time period from the moment of initiating the water exchange with the sea, during which the lagoon reaches the water salinity limit of 7-8 ‰, that is critical for the existence of freshwater species of flora and fauna, is expected to amount to 4 months for the southern part and to 5.5 months for the northern part of the lagoon; after which the formation of the marine ecosystem of the reservoir will begin. It is shown that the stabilization of water salinity in the lagoon in the second year of the simulation can be achieved under conditions of ensuring the Danubian freshwater discharge in the period of significantly higher water level in the Danube River, compared to the lagoon water level (May-July 2019).

The paper presents the results of research of heavy and extreme precipitation in the form of rain (> 50 mm / 12 h) and snow (> 20 mm / 12 h) using the data from the atmospheric reanalysis ERA5 for the period of 1979-2019. According to the data of the European Centre for Medium-Range Weather Forecasts obtained through the numerical modeling and resulting from the data assimilation at the nodes of a regular grid with a spatial resolution of 0,25°×0,25°, there are 131 and 136 days with rain and snow during which precipitation intensity reached the criteria of meteorological phenomena of the 2nd and 3rd levels of danger. It was discovered that the last 40 years in Ukraine proved to have a tendency of an increased number of cases of heavy snowfall, and a slightly decreased number of heavy rains. The research pays considerable attention to the spatial-temporal analysis of the frequency and intensity of heavy rainfall with consideration of geographical factors. It determines the seasonal course of heavy and extreme precipitation, the maximum and minimum values of which did not differ from the climatic standard values observed during meteorological observations. Rainfalls with precipitation rates of more than 50 mm over 12 hours were observed almost over the entire territory of Ukraine and the maximum frequency zones were detected over the Carpathian Mountains, Donetsk Ridge, Podolsk Upland, and the south-western part of the country. Heavy snowfalls with more than 20 mm precipitation over 12 hours mostly occurred in the Carpathian region. The analysis of the geographical distribution revealed a center with maximum values of rain intensity (120-133 mm over 12 h) off the coast of the Sea of Azov, and the heaviest snowfalls (34-38 mm over 12 h) mainly formed in the Carpathian region. The paper established the types of elementary circulation mechanisms of Dzerdzeevsky’s synoptic classification of Northern Hemisphere atmospheric circulation. These types, when continuous in nature, resulted in a significantly increased precipitation in the form of rain and snow. According to the reanalysis data, cases with the maximum rain intensity were found over the period of 23 to 27 July 2008 when a catastrophic flood was observed in the Ukrainian Carpathians. This fact indicates that the structure of the field of heavy precipitation over the territory of Ukraine was adequately reproduced by the respective model of the European Centre for Medium-Range Weather Forecasts.

Since modern research indicates climatic changes in all regions of our planet, including on the territory of Ukraine (in particular, the deviation of temperature and other meteorological parameters from the values of the climatic norm), their study is extremely important. After all, they can lead to changes in the nature of precipitation distribution, the length of the growing season, a decrease in the duration of the stable snow cover, local runoff water resources, etc. Most scientific works in recent years describe changes in the distribution of temperature characteristics and precipitation regime, because they are one of the main indicators of the state of the climate system. Therefore, the purpose of this article is to identify the features of changes in air temperature and precipitation for the entire territory of Ukraine from 2021 to 2050 based on the results of 16 simulations of the ensemble of CORDEX models based on the RCP4.5 scenario. The CORDEX project is a modern simulation of the future climate and has a resolution of ~ 12.5 km in the horizontal plane, which makes it possible to better simulate the characteristics under study. It integrates regional climate predictions that are generated using statistical and dynamic methods. The results obtained are presented for 177 cities of Ukraine, which currently form the basis of a modern monitoring network. It was found that the number of days with precipitation ≥ 5 mm in transitional seasons increases on average by 1-3 days per month, depending on the region. The maximum values of the frequency of occurrence of the number of days with precipitation ≥ 5 mm are observed in the west and gradually decrease in the south. Compared to 1961-1990, the most significant changes occur with the number of frosty days with an air temperature of ≤ 0°С, which noticeably decreases during the study period from north to south. In April and October, for the southern regions of Ukraine, the considered parameter is equal to 0, which means that in these months the air temperature for these regions will have positive values. From the above, there is a tendency towards warming in transitional seasons and a change in the nature of moisture supply to the territory of Ukraine in the next thirty years.

The article describes the finite-difference solution of the system of differential equations of the atmospheric boundary layer hydrothermodynamics adapted to the Northwestern Black Sea region. The research presents the description of the sequence of calculations schematically shown on the flowchart. The applied mathematical model was adapted in relation to five aspects: coast geomorphology (coastline shape), land geomorphology (actual terrain of the studied territory), thermal and physical characteristics of soil (density, specific gravity, porosity, thermal conductivity factor), roughness (roughness parameter) and optical characteristics (albedo) of the underlying surface. The coastline shape was described with consideration of water proportion available in the current cell of the spatial grid. If the proportion exceeded 50 %, it was assumed that such cell includes land, and vice versa. The terrain matrix was formed by removing the elevation values at each point of the calculated area from official electronic elevation maps. The thermal and physical characteristics of the soil were set depending on a type of soil observed at the current calculated point. The method of roughness elements double recording during growing and non-growing periods of the year was used to consider the roughness of the underlying surface. This method consists in the fact that, depending on the agricultural zoning and its subject content, there is a certain background weighted average value of roughness elements ensemble elevation that transforms into a roughness parameter through the proportionality factor. In such a case, the proportionality factor is linked to a type of a real roughness element at a specific point. Thus, a comprehensive assessment of roughness features of the territory under study was obtained. The albedo of the underlying surface was taken for three various periods of the year: growing period (April-September), post-growing period – months before winter and the first month of spring (October-November, March) and winter period (December-February). Nature of the external coating of the underlying surface related to optical properties should be also taken into account.

The paper topicality consists in the necessity for determination of the environmental status of the rivers in the Siverskyi Donets Basin and assessment of the possibilities for them to achieve ‘good environmental status’ under the modern climatic conditions and the anthropogenic load. Siverskyi Donets is the main river in the Eastern Ukraine. There are large industrial zones at the water catchment area. Among them, there are the Donetsk Coal Basin and the industrial complexes within the City of Kharkiv, which have exerted influence on surface water quality for decades. A method for assessment of the pollution level and the environmental status of waters by the hydrochemical index of BOD5 (biochemical oxygen demand for 5 days) is used in the paper. The paper is aimed at identification of the main trends in water quality changes by hydrochemical index of BOD5. The object of research is a pollution of the rivers at the Siverskyi Donets Basin by industrial, municipal and mine wastewaters. The subject of research is an assessment of water qualitative status by BOD5. The hydrochemical observation data for 7 gauges at the main river and 7 tributaries for the period of 1990-2015 were used in the paper. The major attention is focused on the most polluted rivers in the Eastern Ukraine: the Udy and the Kryvyi Torets. The quality of the Udy River water is largely determined by the municipal wastewater from Kharkiv. The Kryvyi Torets River belongs to the Donbas rivers, where pollution by mine water and wastewater from industrial enterprises is significant. Pollution levels, environmental status and saprobity were determined by the average annual indices of BOD5. Empirical probabilities for occurrence of a certain pollution parameter at various gauges were calculated for comparative analysis. It is found that a BOD5 downward trend has been prevalent on the rivers at the Siverskyi Donets catchment area in the early 21st century. The highest BOD5 values were observed on the Donbas tributaries and the Udy River (downstream from the City of Kharkiv), as well as upstream and downstream from Lysychansk, and the lowest ones were observed on the Oskil River. It is also revealed that in the early 21st century, the main river water has a ‘threshold’ environmental status (β-mesosaprobic zone), except for the Lysychansk gauge, where the status is ‘irreversibly altered’ owing to the inflow of polluted water from Donbas rivers into the Siverskyi Donets. Research into the Udy River water quality upstream and downstream from the industrial city of Kharkiv has shown that the water in the upper reaches of this river is classified as ‘clean’ and ‘moderately polluted’, and the environmental status may become ‘good’ in the future. Downstream from the city, the water is mostly ‘dirty’, and the environmental status is ‘irreversibly altered’, which corresponds to the α-mesosaprobic zone. For the Kryvyi Torets River (the Donbas Region), owing to the impact of organic pollution, the environmental status is defined as ‘threshold’, ‘irreversibly altered’ and it has begun to deteriorate in recent years. To improve the environmental status of the Donbas rivers, the reduction in discharges of untreated municipal and industrial wastewater into surface watercourses, as well as the construction of state-of-the-art sewage treatment plants are necessary.

The article studies one of the most important issues of agricultural production maintenance – development of a system of crops area estimation in Ukraine. The objective of this paper is to describe the similar system that uses high resolution satellite data and operational agrometeorological data from the network of the Hydrometeorological Centre of Ukraine as input information. The system is based on step-by-step solving of the following tasks: obtaining geoinformation data for individual agricultural crops; development of methods for multispectral satellite images classification; development of software applications to automate the process of these images classification with subsequent classification of crop areas. The research uses the following algorithms (or classifiers) to classify the agricultural land: SVM (support vector machine), RF ("random forest") and NN (neural networks). The choice of the most accurate of them formed the basis of the general method of classification. The values of spectral characteristics of red and infrared channels of a complete set of cloudless satellite images during the growing period were used as input data (features). As a result, in 2018 some test calculations were conducted to estimate the area of agricultural crops in Kyiv Region. The results of evaluation of accuracy of the satellite-based agricultural crops area estimation using the statistical data showed that the lowest accuracy is typical for winter wheat and corn. The accuracy of soybeans and spring barley classification is quite low for most of the tested fields. Sunflower and rapeseed crops showed the highest accuracy. In order to improve the accuracy of classification, it is necessary to introduce more classification features (in a temporary aspect) by processing more satellite images during the growing period, and to increase the number of test samples through systematic sampling of ground data across the regions in Ukraine. We suggest using the scheme of main agricultural crops area estimation satellite-based system by the Hydrometeorological Centre of Ukraine.

This study proposes climate security: a research agenda proposal with certain research significance. It acknowledges the United Nations Framework Convention on Climate Change (UNFCCC), the European Union (EU) and the United Nations Security Council (UNSC) as key actors in and current institutional case studies for international climate politics. It answers the question of the extent to which climate security scholars have mapped the field with respect to these three institutions. To do this, it reviews relevant literature of climate security and concisely summarizes the literature views. Although climate security scholars have studied how these specialist institutions have understood global climate governance, a comparative coverage of how the institutions have conceptualized climate security is missing in existing literature. The key finding shows the concepts of epistemic communities, climate securitization and climate-riskifications as appropriate analytical themes for interpreting the emerging norm of climate security. Arguing that conceptual development persists even though the institutions original mandates did not require such conceptualization, the study uses discourse analysis of relevant literature on climate security to orient future research on climate change and climate security given the knowledge that speech-acts on climate security (henceforth speech-acts) now seem like potential policy consideration in the foreseeable future.

The article presents the developed artificial neural network for F2 ionosphere layer traces scaling on ionograms obtained using the IPS-42 ionosonde installed at the Ukrainian Antarctic Akademik Vernadsky station. The parameters of the IPS-42 ionosonde and the features of the data obtained with it, in particular the format of the output files, are presented. The advantages of using an artificial neural network for identification of traces on ionograms are demonstrated. Usually, an automatic scaling of the ionograms requires a lot of machine time however implementation of an artificial neural network speeds up computations significantly allowing to process incoming ionograms even in the real time mode. The choice of architecture of an artificial neural network is substantiated. The U-Net architecture was chosen. The method of creating and training the neural network is described. The artificial neural network development process included choosing the number of layers, types of activation functions, optimization method and input layer size. Software developed was written in Python programming language with use of the Keras library. Examples of data used for training of the artificial neural network are shown. The results of testing an artificial neural network are presented. The data obtained with the artificial neural network are compared with the results of manual processing of ionograms. Data for training the artificial neural network were obtained in March, 2017 using the IPS-42 ionosonde installed at the Ukrainian Antarctic Akademik Vernadsky station; data for testing were obtained in 2017 and 2020. The developed artificial neural network has minor flaws but they are easily eliminated by retraining the network on a more representative dataset (obtained in various years and seasons). The general results of testing indicate good prospects in further developing this artificial neural network and software for working with it.

It is remarkable that the high-end sea level rise threat over the next few hundred years comes almost entirely from only a handful of ice streams and large glaciers. These occupy a few percent of ice sheets’ coastline. Accordingly, spatially limited interventions at source may provide globally-equitable mitigation from rising seas. Ice streams control draining of ice sheets; glacier retreat or acceleration serves to greatly increase potential sea level rise. While various climatic geoengineering approaches have been considered, serious consideration of geotechnical approaches has been limited – particularly regarding glaciers. This study summarises novel and extant geotechnical techniques for glacier restraint, identifying candidates for further research. These include draining or freezing the bed; altering surface albedo; creating obstacles: retaining snow; stiffening shear margins with ice; blocking warm sea water entry; thickening ice shelves (increasing buttressing, and strengthening fractured shelves against disintegration); as well as using regional climate engineering or local cloud seeding to cool the glacier or add snow. Not all of these ideas are judged reasonable or feasible, and even fewer are likely to be found to be advisable after further consideration. By describing and evaluating the potential and risks of a large menu of responses – even apparently hopeless ones – we can increase the chances of finding one that works in times of need.

The human-food sector is one of the most challenging areas when it comes to greenhouse gas (GHG) reduction. In this study, recipes from similar cookery books were analysed to identify the extent to which CO2 reduction can be achieved cost-effectively by cooking vegan, ovo-lacto-vegetarian or meat-containing recipes. A total of 311 recipes from six different German omnivorous, vegetarian and vegan cookery books were analysed in terms of GHG emissions and costs. The results illustrate that, based on calories, the vegan recipes on average lead to a 10% reduction in GHGs compared to vegetarian recipes and a 65% reduction compared to recipes high in meat. The costs for vegan recipes are 45% higher than those for vegetarian recipes. The relatively high prices for vegan dishes result from the cost of meat and dairy replacement products. Overall, GHG emissions from vegan recipes are only slightly lower than those from vegetarian recipes.

Antarctic Peninsula region is experiencing one of the fastest rates of climate change on Earth. Its waters are known as important feeding grounds for the Antarctic minke whales (Balaenoptera bonaerensis). The purpose of the present study was to reveal the summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula of West Antarctica and to estimate the encounter rates of the species in the area. The boat-based photo-identification cetacean studies were initiated as part of the long-term monitoring program based at the Akademik Vernadsky station near the Kiev Peninsula of West Antarctica. From 22 January to 7 April 2019, 35 boat and yacht cruises of the 821 nautical miles of total length were conducted. There were encountered 13 Antarctic minke whales in 7 sightings. The encounter rate was 0.015 whales per nautical mile. Minke whales were encountered only in 5% of the total sightings. Three more whales were opportunistically seen from the top of Galindez Island. There were single whales sighted and small groups of up to 3 specimens (Med = 2). At least 2 individuals were identified as juveniles. Primary behavior for whales in 7 sightings was foraging, and 2 groups were observed while travelling. A total 9 individuals of the Antarctic minke whales were photo-identified during the survey, and no matches were found between the different encounters. Our pilot study indicates summer and early autumn presence of the Antarctic minke whales in the area adjacent to the Kiev Peninsula. But encounter rates seem to be low in comparison with results of some previous surveys. Our results show the possibility to monitor minke whales in the area, and further long-term complex monitoring is essential for understanding the ecology and population dynamics of the Antarctic minke whales in rapidly changing marine environment of the Antarctic Peninsula.

In the paper the seasonal trends in the zonal asymmetry in the quasi-stationary wave pattern of total ozone column (TOC) at southern polar latitudes have been investigated. We evaluated and compared seasonal trends in the zonal TOC asymmetry from modern era satellite measurements using the Total Ozone Mapping Spectrometer data and the second Chemistry Climate Model Validation (CCMVal-2) assessment. The model longitude phase shifts in asymmetry are in general consistent with the eastward phase shifts observed in historical period 1979–2005, however, there are underestimated values in individual seasons. Future trends in zonal asymmetry from the eleven CCMVal-2 models up to 2100 are presented. They demonstrate the appearance of reverse (westward) future phase shifts, mainly in austral summer. The results are in agreement with previous study and highlight that the general eastward/westward phase shift is caused by both greenhouse gases changes and ozone depletion/recovery. The greenhouse gases change drives a basic long-term eastward shift, which is enhanced (decelerates or reverses) in austral spring and summer by ozone depletion (recovery). The trends in the TOC asymmetry are forced by a general strengthening of the stratospheric zonal flow, which is interacting with the asymmetry of the Antarctic continent to displace the quasi-stationary wave-1 pattern and thus influences the TOC distribution. The results will be useful in prediction of seasonal anomalies in ozone hole and long-term changes in the local TOC trends, in ultraviolet radiation influence on the Southern Ocean biological productivity and in regional surface climate affected by the zonally asymmetric ozone hole.

Non-extractive method for the benthic wildlife study using the underwater video system (UVS) recording was provided during the research survey with the bottom longline in the northwestern part of the Weddell Sea. At the longline survey stations the data on wind direction and speed, state of the sea, air temperature, cloudiness, ice concentration, atmospheric pressure, precipitation, depth and coordinates of the anchor setting, direction of the longline set also were collected. It was found that the UVS with additional light during video recording does not disturb the animal behavior at depths of 700–1100 m in the study area. Three UVS observations have been described. The slope of the northwestern part of the Weddell Sea can be considered as spawning site of squid (Slosarczykovia circumantarctica). The data indicate wide distribution of Antarctic krill (Euphausia superba) and Antarctic jonasfish (Notolepis coatsi) in the area. The high density of the adult Antarctic jonasfish in a single place has never been recorded before. Preliminary observations and analysis of video recordings showed that the shooting lighting andobservation distance are sufficient for observing and identifying animals, their behavior and movement. This technique will allow estimating the relative species abundance and size distribution.

Reductions in the transportation sector's carbon dioxide emissions are increasingly of global concern. As one of the first low-carbon pilot and carbon trading pilot cities, and as one of the largest automobile production bases in China, Chongqing has multiple low-carbon transportation policies that are coupled. In this study, three policy scenarios are set, including: 1) improving the fuel economy of newly sold gasoline passenger cars to 5.7 l per 100 km by 2020, 2) promoting pure electric private cars to increase the share to 7% of private car sales by 2020, and 3) the policy mix scenario of the above two policies. Simulations are undertaken with the Chinese Academy of Sciences general equilibrium (CAS-GE) model, a type of computable GE model, to assess the macro-economic impact and the industrial impact of the three policy scenarios. Through the policy impact mechanism analysis and data-mapping process, the micro-economic impact analysis results, including costs and fuel savings, for the two policies from the bottom-up model are taken as the shock variables and inputs for the CAS-GE model. The results show that: 1) the two policies will both have a slightly negative impact (−0.09% and −0.30%) on Chongqing's GDP in 2020; 2) the employment rate will decrease by 0.12% and 0.47%, but the inflation rate will be restrained to a certain extent (−0.21% and −0.17%); and 3) the complementarity of the mixed policy can weaken the negative impact of the two policies when implemented separately. The mixed policy will reduce the GDP slightly by 0.37%, compared with the cumulative effect of the two policies implemented separately, resulting in cost-effective synergies at the macro-economic impact level; and 4) the COVID-19 pandemic in 2020 has an uncertain impact on the results. The method and results can provide a reference for the formulation and adjustment of low-carbon transportation policies in other large cities.

Using the daily maximum temperature of the RegCM4 dynamical downscaling from four global climate models under the historical and RCP4.5 simulations, this study firstly identified the cluster high temperature event (CHTE) occurring in China through a simplified objective method, and then projected its change during the 21st century in terms of the CHTE metrics including frequency, duration, extreme intensity, cumulative intensity, maximum influential area, average influential area, and comprehensive intensity. The ensemble projection indicates that all the CHTE metrics tend to increase toward the end of the 21st century on the national scale. Besides, the occurrence of CHTE shows a longer month span during the middle and the end of the 21st century (from April to October) compared to the present (from April to September), accompanied with the peaks of the frequency, duration, and cumulative intensity shifting from the present July ahead to June. Relative to 1986–2005, the projected slight, moderate, and extreme CHTEs increase by 55%, 50%, and 50% (58%, 43%, and 60%) during 2046–2065 (2080–2099), respectively; the projected severe CHTE increases by 11% during 2046–2065 while decreases by 11% during 2080–2099. Spatially, the CHTE frequency, duration, and cumulative intensity are projected to increase in a widespread region. The largest increase appears in southern China for the frequency and in Xinjiang and Southeast China for the duration and cumulative intensity. We further divided China into five sub-regions to examine the regional features of CHTE changes. It is found that in addition to the increase of CHTEs in each single sub-region, a pronounced enhancement is also projected for the occurrence of cross-regional CHTEs, particularly for that across more than two sub-regions.

Land models are essential tools for understanding and predicting terrestrial processes and climate–carbon feedbacks in the Earth system, but uncertainties in their future projections are poorly understood. Improvements in physical process realism and the representation of human influence arguably make models more comparable to reality but also increase the degrees of freedom in model configuration, leading to increased parametric uncertainty in projections. In this work we design and implement a machine learning approach to globally calibrate a subset of the parameters of the Community Land Model, version 5 (CLM5) to observations of carbon and water fluxes. We focus on parameters controlling biophysical features such as surface energy balance, hydrology, and carbon uptake. We first use parameter sensitivity simulations and a combination of objective metrics including ranked global mean sensitivity to multiple output variables and non-overlapping spatial pattern responses between parameters to narrow the parameter space and determine a subset of important CLM5 biophysical parameters for further analysis. Using a perturbed parameter ensemble, we then train a series of artificial feed-forward neural networks to emulate CLM5 output given parameter values as input. We use annual mean globally aggregated spatial variability in carbon and water fluxes as our emulation and calibration targets. Validation and out-of-sample tests are used to assess the predictive skill of the networks, and we utilize permutation feature importance and partial dependence methods to better interpret the results. The trained networks are then used to estimate global optimal parameter values with greater computational efficiency than achieved by hand tuning efforts and increased spatial scale relative to previous studies optimizing at a single site. By developing this methodology, our framework can help quantify the contribution of parameter uncertainty to overall uncertainty in land model projections.

A trinomial tree model based on a real options approach was developed to evaluate the investment decisions on carbon capture, utilization, and storage (CCUS) retrofitted to the three main types of thermal power plants in China under the same power generation and CO2 emissions levels. The plant types included pulverized coal (PC), integrated gasification combined cycle (IGCC), and natural gas combined cycle (NGCC) plants. We take into account a subsidy policy consistent with the 45Q tax credit of the U.S., as well as uncertainty factors, such as carbon price, technological progress, CO2 geological storage paths, oil price, and electricity price. The results showed that the investment benefit of ordinary NGCC power plants is 93.04 million USD. This provides greater economic advantages than the other two plant types as their investment benefit is negative if the captured CO2 was used for enhanced water recovery (EWR), even if 45Q subsidies are provided. Compared with NGCC + CCUS power plants, PC + CCUS and IGCC + CCUS power plants have more advantages in terms of economic benefits and emission reduction. The 45Q subsidy policy reduced the critical carbon price, which determines the decision to invest or not, by 30.14 USD t−1 for the PC and IGCC power plants and by 15.24 USD t−1 for the NGCC power plants. Nevertheless, only when the subsidy reaches at least 71.84 USD t−1 and the period limit is canceled can all three types of power plants be motivated to invest in CCUS and used the capture CO2 for EWR. Overall, the government should focus on the application of CCUS in coal-fired power plants (in addition to developing gas power generation), especially when CO2 is used for enhanced oil recovery (EOR). The government could introduce fiscal policies, such as 45Q or stronger, to stimulate CCUS technology development in China.

The study presents analysis of microclimatic conditions on Galindez Island (western part of the Antarctic Peninsula), in particular: seasonal variability and spatial heterogeneity. Based on land surface temperature (LST) data derived from loggers and MicroClimate Monitoring Station, we analyzed areas with active growth of local plants. Seasonal variations formed mainly under annual and semi-annual cycles, with no dependencies of amplitudes and phases form area location. LST highly correlates with air temperature and total incoming irradiance. It is emphasized that spatial orientation of relief microforms plays the most significant role for LST formation on micro-level. Using cluster analysis, it was found that temperature loggers which are located along shoreline and oriented to the north–north-east could be grouped by similar LST distribution.

A clear understanding of the changes of water resources under the background of environmental changes is of great significance for scientific management and utilization of water resources in China. This study systematically analyzed the spatial–temporal variations of surface water resources in China since 2000. Water vulnerability in current (2010s) and its trends from 2000 to late-2010s in different regions of China were also summarized. In addition, the correspondingly adaptive measures to counter regional risks to water resources were proposed. We concluded that the runoff of major rivers had been decreasing in eastern China and increasing in western China during 2000–2018. In the arid area of Northwest China, the alpine runoff has shown an overall upward trend since the late-1990s/early-2000s, with a 10%–25% increase caused by the increase of glacial meltwater and precipitation. While the runoff of each hydrological station in the 2000s–2010s was 34.7% lower than that in the 1950s–2010s on average. The increases in precipitation and glacial meltwater with global warming caused a rapid expansion of lakes in the Qinghai-Tibet Plateau and Xinjiang, thus leading to an increase in total area and water quantity of lakes in China from 1995 to 2015. The mean contribution rates of climate change and human activity to runoff change in river basins of China were 53.5% and 46.5%, respectively, during the period of 2000–2010s. The driving factor of runoff change in many river basins has gradually changed from climate change (1950s‒2000) to human activity (2000–2018). During 2000–2018, the contributions of human activities to runoff change were 50%–80% in major rivers of eastern China. The vulnerability in most areas of Northwest China and North China is generally high, with the vulnerability index greater than 0.6. Comparatively, in Northeast, East, South, and Central China, it is lower or not vulnerable. In Southwest China, the vulnerability varies greatly with Yunnan and Sichuan relatively low while Chongqing and Guizhou relatively high. The precipitation increase, the application of water-saving technology, the establishment of flood control and drought relief engineering facilities, and the introduction of relevant policies and measures have helped to gradually reduce the vulnerability of water resources in most areas of North and Northwest China (except Xinjiang) from 2000 to 2010s. Water vulnerability has been increasing in southern China, caused by climate change and the development of industry and agriculture, which increases water resource exposure since 2000. Based on the typical risk factors and vulnerability characteristics of water resources in different regions, this study proposed some targeted adaptive measures correspondingly so as to scientifically deal with the problems of surface water resources in China.

The Antarctic Peninsula region is of growing interest due to the regional climate change features and related atmospheric circulation patterns. The regional mesoscale atmospheric model Polar Weather Research and Forecasting (WRF) v4.1.1 was used in this research to study a heavy precipitation event over the Ukrainian Antarctic Akademik Vernadsky station region (Antarctic Peninsula). The passage of the cyclone over the Antarctic Peninsula as a typical synoptic process as well as a case of the daily precipitation maximum amount of 2018 were chosen for investigation in this research. The estimation of the modelling quality and downscaling was done by comparing the obtained results with in-situ observation at the Akademik Vernadsky station and cross-domain tracking of average meteorological values and their deviation. The concept of the nested domains allowed to increase the horizontal resolution of the simulated atmosphere up to 1 km and to reproduce the wind regime of this region with high quality. Comparison with measured data showed a significant improvement in wind simulation with increasing of resolution, but worse representation of surface temperature and humidity. The Polar WRF made a general cooling of near surface temperature of 2 °C during the period of simulation and increased precipitation amount by 4.6–8.4 mm (12–21%) on average over the territory relative to the initial data from Global Data Assimilation System. This can be explained by the contribution of noise and imperfection of the model (including static input data of the terrain description). Based on the modelled results, the interaction of wind flow with the mountainous terrain of the Antarctic Peninsula creates a range of complex dynamic effects in the atmosphere. These effects cause local precipitation maxima both over the Peninsula and over the adjacent ocean. These are, respectively, bay-valley areas of increased precipitation and increased precipitation on the crests of shock waves from orographic obstacles. Under certain background wind conditions, the influence of the latter effect can reach the Akademik Vernadsky station and cause the formation of heavy precipitation here.

Antarctica and the Southern Ocean are unique natural laboratories where organisms adapted to extreme environmental conditions have evolved in isolation for millions of years. These unique biotic communities on Earth are facing complex climatic and environmental changes. Terrestrial ecosystems in the Antarctic Peninsula Region (APR) have experienced the highest rate of climate warming and, being the most impacted by human activities, are facing the greatest risk of detrimental changes. This review provides an overview of the most recent findings on how biotic communities in terrestrial ecosystems of the Antarctic Peninsula Region (APR) are responding and will likely respond to further environmental changes and direct anthropogenic impacts. Knowledge gained from studies on relatively simple terrestrial ecosystems could be very useful in predicting what may happen in much more complex ecosystems in regions with less extreme temperature changes. The rapid warming of the APR has led to the retreat of glaciers, the loss of snow and permafrost and the increase of ice-free areas, with a consequent enhancement of soil-forming processes, biotic communities, and food web complexity. However, most human activity is concentrated in APR coastal ice-free areas and poses many threats to terrestrial ecosystems such as environmental pollution or disturbances to soilcommunities and wildlife. People who work or visit APR may inadvertently introduce alien organisms and/or spread native species to spatially isolated ice-free areas. The number of introduced non-indigenous species and xenobiotic compounds in the APR is likely to be greater than currently documented, and several biosecurity and monitoring activities are therefore suggested to Antarctic national scientific programs and tourism operators to minimize the risk of irreversible loss of integrity by the unique terrestrial ecosystems of APR.