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Winter precipitation (P) in East Asia (EA) is characterized by a wetter south and a drier north. Most of the existing research has concentrated on elucidating the mechanisms of winter P in southern EA, with relatively less attention given to northern East Asia (NEA). Our analysis showed that the correlation coefficient (c.c.) of average winter precipitation anomaly percentage (PAP) between southern EA and NEA is 0.24 for the period 1950–2023, indicating substantial regional difference. An empirical orthogonal function (EOF) analysis was conducted on the winter PAP in NEA. The first and second mode (EOF1 and EOF2) account for 45.5% and 17.9% of the total variance, respectively. EOF1 is characterized by a region-wide uniform spatial pattern whereas EOF2 exhibits a north–south dipole pattern. Further analysis indicated that the two EOF modes are related to distinct atmospheric circulation and external forcings. Specifically, EOF1 is linked to a wave train from Central Siberia toward Japan, while EOF2 is connected with an anomaly similar to the Western Pacific pattern. Variations in mid–high latitude sea surface temperatures, sea ice, and snow are potential factors influencing EOF1. EOF2 exhibits a close relationship with tropical SST anomalies. [ABSTRACT FROM AUTHOR]

Abstract: A central goal at the interface of ecology and conservation is understanding how the relationship between biodiversity and ecosystem function (B–EF) will shift with changing climate. Despite recent theoretical advances, studies which examine temporal variation in the functional traits and mechanisms (mass ratio effects and niche complementarity effects) that underpin the B–EF relationship are lacking. Here, we use 13 years of data on plant species composition, plant traits, local‐scale abiotic variables, above‐ground net primary productivity (ANPP), and climate from the alpine tundra of Colorado (USA) to investigate temporal dynamics in the B–EF relationship. To assess how changing climatic conditions may alter the B–EF relationship, we built structural equation models (SEMs) for 11 traits across 13 years and evaluated the power of different trait SEMs to predict ANPP, as well as the relative contributions of mass ratio effects (community‐weighted mean trait values; CWM), niche complementarity effects (functional dispersion; FDis) and local abiotic variables. Additionally, we coupled linear mixed effects models with Multimodel inference methods to assess how inclusion of trait–climate interactions might improve our ability to predict ANPP through time. In every year, at least one SEM exhibited good fit, explaining between 19.6% and 57.2% of the variation in ANPP. However, the identity of the trait which best explained ANPP changed depending on winter precipitation, with leaf area, plant height and foliar nitrogen isotope content (δ15N) SEMs performing best in high, middle and low precipitation years, respectively. Regardless of trait identity, CWMs exerted a stronger influence on ANPP than FDis and total biotic effects were always greater than total abiotic effects. Multimodel inference reinforced the results of SEM analysis, with the inclusion of climate–trait interactions marginally improving our ability to predict ANPP through time. Synthesis. Our results suggest that temporal variation in climatic conditions influences which traits, mechanisms and abiotic variables were most responsible for driving the B–EF relationship. Importantly, our findings suggest that future research should consider temporal variability in the B–EF relationship, particularly how the predictive power of individual functional traits and abiotic variables may fluctuate as conditions shift due to climate change.

• Wetter winters as a result of climate change increase N and S topsoil availability in forests. • Surprisingly high leaching rates of additionally available nutrients. • No short-term effects of wetter winters on decomposition and tree growth. • Groundwater N and S pollution likely increases with winter climate change. Climate models project moderate to large increases in air temperature for most temperate ecosystems with an overall increase in winter precipitation and a shift from snow towards rain. We investigated the effects of increased winter rainfall on the ecosystem functioning of European beech forests at their north-eastern distribution range. In a large-scale field experiment we manipulated winter climate at nine forest sites by increasing the amount of rainfall and excluding snow. Nutrient availability in the topsoil and leaching in 50 cm depth as well as litter decomposition and radial growth of mature European beech trees were analysed. It was hypothesized that (1) wetter winters lead to increased nutrient deposition as well as leaching, with an overall increase in net nutrient availability, (2) decomposition decreases in response to water addition containing also additional nutrients and (3) primary production during the subsequent growing season increases as presumably not all additionally available nutrients would be leached. We found an increase in topsoil nitrate and sulfate availability during winter in response to rain addition, likely as a consequence of collecting more atmospheric deposition, and surprisingly high leaching rates of the additionally available nutrients. During the subsequent early growing season, no difference in nutrient availability could be observed anymore. Enhanced nutrient availability in the topsoil and leaching do not seem to have a strong short-term influence on forest ecosystem processes in ecosystems which are close to their critical load of N deposition. Decomposition rates during winter and early growing season as well as stem diameter growth during the following growing season were not influenced. This indicates that additional nutrients in the topsoil in response to wetter winters are not available for plant growth but pollute ground- and surface waters. [ABSTRACT FROM AUTHOR]

The influence of winter circumglobal teleconnection （CGT） on the interannual variability of winter precipitation in the Southeast Asian low-latitude highlands were statistically analyzed using ERA5 reanalysis data from the European Centre for Medium-Range Weather Forecasts （ECMWF）， monthly mean precipitation data from the Climate Hazards Group Infrared Precipitation with Station data （CHIRPS） developed by the United States Geological Survey and the University of California and the monthly mean precipitation data of the Global Precipitation Climatology Project （GPCP） provided by the Global Precipitation Climatology Center.Results of correlation analysis show that the CGT presents two main patterns with approximately the same variance contribution rate.On the vertical direction， the CGT shows an equivalent barotropic structure with four anomalous centers.During the CGT positive phase， the negative anomalous centers are located near the Mediterranean Sea and the Indian Peninsula， and the positive anomalous centers near the Arabian Peninsula and Southeast Asian low-latitude highlands.The first mode of CGT （CGT1） significantly correlates with winter precipitation over the Southeast Asian low-latitude highlands on the interannual time scale.When the CGT1 is in the positive phase in winter， the anomalous "anticyclone， cyclone， anticyclone， cyclone" control the Western Europe， the northwestern Arabian Peninsula， the Arabian Sea and Southeast Asian low-latitude highlands， respectively.The anomalous southwesterly wind on the east side of the anomalous cyclone will increase the water vapor from the Bay of Bengal and the South China Sea to the Southeast Asian low-latitude highlands.The more water vapor converged and condensed in Southeast Asian low-latitude highlands finally results in heavier winter precipitation over the Southeast Asian low-latitude highlands.On the contrary， when the CGT1 is in the negative phase in winter， the Western Europe， the northwestern Arabian Peninsula， the Arabian Sea and the Southeast Asian low-latitude highlands are controlled by the anomalous "cyclone， anticyclone， cyclone， anticyclone".The anomalous northeast wind on the east flank of the anomalous anticyclone will reduce the water vapor from the Bay of Bengal and the South China Sea to the Southeast Asian low-latitude highlands.The anomalous divergence and descending motion further lead to less precipitation in winter over the Southeast Asian low-latitude highlands.The significant positive correlation between CGT and precipitation over the Southeast Asian low-latitude highlands， sharing almost the same key physical process as winter， can be observed in December， January and February.Results of typical case further confirm the key physical process through which the CGT modulates the interannual variability of winter precipitation over the Southeast Asian low-latitude highlands.

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Based on the 103 stations precipitation over Songhua River Basin （SRB）， the reanalysis data of NCEP/NCAR， the sea surface temperature （SST） from NOAA， the interannual variation in snowfall over SRB and its relationship with west north Pacific SST anomalies （SSTA） during boreal winter for 1979 -2019 are investigated by using statistical analysis methods.The results show that the snowfall over SRB during winter is mainly characterized by its interannual variation （explains 83.3% of total variation）， and the first leading EOF mode of interannual snowfall anomalies of SRB during winter is dominated by a homogeneous structure （explains 55.3% of total variance） indicating significant covariability over the SRB.The atmospheric circulation associated with the interannual SRB winter snowfall suggests that the above-normal （below-normal） snowfall is induced by positive （negative） geopotential height anomalies over the region from Okhotsk to Aleutian island and negative （positive） geopotential height anomalies over the mid-low latitude to the south of Okhotsk Sea.Further analyses indicate that the dipole structure of SSTA over WNP during winter has a profound impact on the simultaneous interannual snowfall over SRB.The positive WNP SSTA dipole （positive and negative SSTA over Japanese Sea and east to the Philippines Islands， respectively） can induce positive geopotential height anomalies in the upper troposphere and anomalous anticyclone in the lower troposphere in the mid-high latitudes over WNP， as well as the negative geopotential height anomalies in the upper troposphere and anomalous cyclone in the lower troposphere in the mid-low latitudes.The region from north Pacific to the SRB is covered by anomalous southeasterly winds during winter under the influence of these anomalous atmospheric circulation.As a result， the moisture from the sea to the south of Aleutian and the sea to the east of China are transported to the SRB accompanied by anomalous convergent flow in situ， which are favorable for the increasing snowfall over SRB； and vice versa.

Winter (December to March) precipitation is the major source of rainfed agriculture, storage, and perennial water flow in the western river system of Pakistan. Hence, this study uses precipitation data and variables of land–ocean and atmosphere from the Pakistan Meteorological Department and European Centre for Medium-Range Weather Forecasts (ECMWF) and fifth-generation reanalysis data (ERA5), respectively, to investigate the changes in winter precipitation and its sensitivity to different land–ocean and atmosphere variables, which are rarely investigated in Pakistan. Non-parametric techniques, such as the modified Mann–Kendal, Sen slope, kernel density-based probability function (PDF), empirical orthogonal function (EOF), and correlation analysis, were used to assess the changes and modes of variability in winter precipitation. The overall seasonal precipitation showed a significant decreasing trend with a (−0.1 mm d−1 yr−1) in the seasonal mean and monthly precipitation, except in February which showed a significant increase (>0.11 mm d−1 yr−1). The highest decrease in daily precipitation (<−0.1 mm d−1 yr−1) was in the north, with a moderate decrease in the southeast. The extreme precipitation indices exhibited an erratic decreasing tendency, but the maximum daily precipitation index increased; post-2000 precipitation extremes displayed an increase, and the seasonal and monthly precipitation exhibited the highest deviations during the drought period (1995–2000). The leading precipitation mode (EOF1) is sensitive to the local land surface processes and significantly correlated (>0.60) with the central Pacific and Indian Ocean's basin-wide sea surface temperature, corroborating the influence of ENSO-induced meridional/zonal deviation of Hadley–Walker circulations. The Hadley and Walker cells affect the south-westerlies' jet stream strength, impacting the water vapor transport and precipitation over Pakistan. These changes in the precipitation magnitude will affect rain-fed agriculture, especially the Rabi cropping pattern and perennial river flow. [ABSTRACT FROM AUTHOR]

Link for citation: Samoilova S.Yu., Lovtskaya O.V., Kudishin A.V., Arnaut D.V. Analysis of factors for formation of the Chumysh river maximum runoff (Western Siberia). Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 5, рр.116-128. In Rus. The relevance of the study stems from the necessity to refine the methods of medium-term flood forecasts when sufficient hydrometeorological data are not available. The purpose of the work is to assess probable application of spatially distributed precipitation models to forecast runoff volume of flood, to develop stochastic models for predicting flood volume and its maximum discharge using hydrometeorological observation data, distributed precipitation datasets from reanalysis and remote sensing data of high spatial and temporal resolution. Methods include geoinformation, complex geographical and hydrometeorological analysis, statistical methods (correlation and regression analysis). Results. The Chumysh basin moistening was estimated due to the data from spatially distributed precipitation models and hydrometeorological observation data; the relationship of total precipitation with runoff volume and maximum flood discharge was analyzed. A comparative evaluation of the obtained dependencies made it possible to identify key predictors for deriving the multiple linear regression equation. The statistical model was developed for predicting volumes and maximum discharges of Chumysh flood at Talmenka settlement using hydrometeorological observation data and reanalysis ones of high spatial and temporal resolution.

Copyright of Plateau Meteorology is the property of Plateau Meteorology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Chapingo Serie Ciencias Forestales is the property of Universidad Autonoma Chapingo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract The India–Burma troughs (IBTs) with different shapes (i.e., narrow and wide IBT-like circulations) can significantly affect winter precipitation over different regions in southern China through modulating the paths of water vapor transportation ahead of the IBTs. The effect of the wide/narrow IBT- (WIBT/NIBT-) like circulation cannot be depicted by traditional IBT indices that mainly focus on the IBT’s intensity. This study defines the WIBT and NIBT indices, which can effectively distinguish different water vapor transportation in front of the WIBT and NIBT and relevant water vapor convergence and therefore successfully reflect different distributions of winter precipitation anomalies over southern China. Further exploration reveals that a Rossby wave from the Mediterranean Sea to the Bay of Bengal (BoB) contributes to the variability of the NIBT, while the El Niño–Southern Oscillation (ENSO) can modulate the variability of the WIBT by stimulating the Matsuno–Gill response. The WIBT and NIBT indices should be considered as important supplements to the traditional IBT indices, which are favorable to more detailed diagnosis and prediction of winter climate over southern China.

The study topicality relates to the analysis of available methods for assessing snow reserves in river basins and forecasting floods. To predict runoff volume and maximum flood levels, statistical models resting on the correlation dependence of runoff parameters on snow reserves or multiple linear regression equations are usually used in the absence of sufficient hydrometeorological information. An important point is that there are no justified comparisons of traditional forecasting methods based on calculations of winter precipitation amount (snow reserves) and statistical models of multiple regression. The aim of the study is to carry out the comparative analysis of methods for calculating winter precipitation amounts in the basin by means of traditionally applied altitude dependencies and the author's estimation method using orographic correction to the velocity of vertical movements of air masses; to carry out the comparative analysis of traditional statistical forecasting methods and models of multiple linear regression by the example of the Amyl River basin. Methods: comprehensive geographical and hydrometeorological analysis; dependence establishment based on long-term hydrometeorological observations using methods of mathematical statistics (correlation and regression analysis); snow reserves simulation with the use of orographic correction to the velocity of vertical movements. Results. By altitude dependencies and the author’s assessment considering orographic correction to the velocity of vertical movements of air masses, two different approaches to estimate of winter precipitation amounts suggest similar statistical dependences with close values of determination coefficients. Models for predicting runoff volumes and maximum flood stages based on pair correlation and multiple regression analysis were developed. The comparative analysis of traditional methods for forecasting runoff layers based on calculations of winter precipitation amount (snow reserves) and statistical models of multiple regression also showed similar results. The applied one-factor dependencies turned out to be the best in forecasting snowmelt-induced maximum levels.

Observations indicate that the winter precipitation over Southeast Asia (SEAP) shows significantly increased trends from 1979 to 2014, which can be partly reproduced under the historical all-forcing simulations from the 12 Coupled Model Intercomparison Project Phase 6 (CMIP6) climate models. By analyzing separate external forcings run with the Detection and Attribution experiments, we find that the effects of anthropogenic forcing rather than natural variation play a primary role in driving the increasing of SEAP trends simulated in the historical all-forcing experiments. Further analysis indicate that the observed increasing trend is closely associated with the decadal shift of the Southeast Asian precipitation after the mid-1990s, which could be also driven by anthropogenic forcing to some extent. Anthropogenic forcing can favor a La Niña-like pattern of sea surface temperature (SST) warming in the tropical Pacific and result in the decadal increase of SEAP via the enhanced zonal SST gradient and the Pacific Walker circulation. This study thus provides some evidence of the impacts of anthropogenic forcing to drive recent changes in the winter SEAP.

The study topicality relates to the effect of climate changes and increased recurrence of dangerous hydrological events on rivers of southern Siberia. The observed and predicted changes in flood regimes are caused by a variety of factors and require different approaches in order to characterize the types of these changes. The aim of the study is stochastic modeling of solid precipitation total in the Abakan river basin, establishing relationship between precipitation and maximum water levels in the Abakan river during the flood period under spatial and temporal variability of hydrometeorological factors. Methods: comprehensive geographical and hydrometeorological analysis, dependence establishment based on long-term hydrometeorological observations using mathematical statistics methods, methods (developed by V.P. Galakhov) for estimating precipitation total in the basin with regard for orographic correction to the velocity of vertical movements in the frontal zone. Results. The crucial factor in the formation of maximum flood levels is winter precipitation amount. Heavy rainfalls during flood recession may significantly influence the maximum water levels. However, climate changes of recent decades in river mountain basins of southwestern and eastern Siberia are evidence of dependences between autumn soil freezing and formation of snowmelt-induced maximum stages. In some years during the flood period, decreased maximum water levels are probable in basins with prevailing foothill plains, unlike those with overwhelmingly mountainous landscapes. We have developed a method for calculating winter annual precipitation total in the Abakan basin taking into account physical features of precipitation formation in the mountains, in particular the orographic correction to the velocity of vertical movements. The independent data suggest that algorithms for calculating snowmelt-induced maximum stages based on regression dependencies do not always give adequate results, therefore updating with regard for freezing processes in the foothill plain is required. Besides, extra observation data are called for obtaining the general statistical dependence.

The accurate identification of precipitation type at ground level is one of the greatest difficulties for forecasters during winter. Special types of precipitation can be a threat to public safety and human health and can disrupt transportation and commerce, causing seriously loss of the economy. Winter precipitation may also cause serious disasters to aircraft navigation. In those situations, the consequences can be catastrophic, with heavy and prolonged freezing precipitation, collapsed power lines causing prolonged power outages, transportation networks of many types completely paralyzed, and even major long-term damage to infrastructure and vegetation in the most severe cases. Therefore, the accuracy of precipitation type is crucial for winter precipitation forecast. Accurate predictions from weather forecast models of timing (onset and duration), intensity, spatial extent, and phase (i.e., precipitation type) are crucial for decision-making and can help minimize the potential impacts. The research progress of precipitation type forecast in recent decades is investigated. The methods and techniques for predicting precipitation phases are reviewed systematically, which can be roughly divided into three categories. The index criterion methods are based on observations, numerical weather prediction weather predictions on thickness, area of warm atmosphere, significance level temperature, regression equation for vertical temperature profile, and model diagnosis. Some of those methods are highly dependent on the accuracy of the numerical model. The second type of methods are based on the microphysical processing scheme of numerical weather prediction model and ensemble prediction system. It includes microphysical scheme method and ensemble prediction method. The last type is the artificial intelligence prediction method including decision tree, artificial neural network, and deep learning etc. In recent years, sophisticated microphysical parameterizations schemes are widely used in high resolution regional forecast models, which help with precipitation-type prediction. The forecast accuracy of precipitation type model has been improved, which has become an important product support in precipitation type forecast. For instance, the precipitation type prediction product of ECMWF and the probabilistic prediction of precipitation type by ECMWF ensemble prediction. The probabilistic prediction has further improved the prediction skills compared with the deterministic model. However, even with such complex algorithms of NWP, correctly predicting what phase of precipitation ends up at the ground remains a challenging task. Besides this, many researches on the formation mechanism of microphysical processes are difficult to be applied to the precipitation type prediction, so it still needs continuous efforts to apply these achievements to improve the precipitation type prediction skill of numerical prediction model and increase the accuracy of precipitation type prediction by artificial intelligence and other technologies.

Previous studies have reported that enhanced eddy moisture convergence causes future increase of winter precipitation in the eastern North America in a warmer climate. This study investigates the mechanisms of the change in moisture convergence. Using ensemble simulations from climate models and composite analysis of moisture budget, we show that in the southeast United States, two thirds of the enhanced moisture convergence is caused by local thermodynamics due to increase of moisture, while one third is caused by stronger eddy wind convergence. In the north, it is primarily caused by the increase of moisture gradient associated with the spatial distribution of both the climatological temperature and the large amplitudes of the eddy temperature in the region of the storm tracks. Results help to better understand the physical mechanism of more winter precipitation in the eastern North America in a warmer climate. Plain Language Summary: It has been reported that winter precipitation will increase in the eastern North America under global warming, which is caused by the enhanced eddy moisture convergence. We perform composite analysis of moisture budget using large ensemble simulations of climate models, and find out that the enhanced eddy moisture convergence in the southeast United States can be explained by the combination of climatological eddy wind convergence and increase of moisture content. The intensity of eddy wind convergence will enhance and contribute about one third of the eddy moisture convergence increase in the southeast United States. In the north of eastern North America, the climatological eddy wind brings more moisture into the region due to enhanced moisture gradient. The contrast of different mechanisms in the south and north can be explained by the climatology and future change of the spatial pattern of water vapor and temperature. These results help us to better understand the physical mechanisms that are responsible for the future precipitation increase during winter in the eastern North America under global warming. Key Points: Winter precipitation increases with warming due to enhanced eddy moisture convergence in the eastern North AmericaLocal thermodynamics associated with increased moisture and stronger eddies induce more moisture convergence in the southeast United StatesEnhanced moisture gradient in regions of large eddy magnitudes causes more moisture convergence in the north of eastern North America [ABSTRACT FROM AUTHOR]

Background and Objectives: When it comes to climate change, the first emphasis should be detecting these changes in high mountainous regions, since they will have a direct impact on water supplies in the major stems. In the Behesht Abad and Koohrang zones of Iran's central Zagros mountains, one of the country's highest mountain ranges, the influence of climate change on snow-rain phase separation in the future is investigated. Because of the Karun River's varied exploitation, understanding how it will evolve in the future and under the effect of climate change is critical. The aim of the research is to determine the consequences of climate change on precipitation in the region, particularly in terms of future changes in snow and rain phases. Materials and methods: For this, the research region's precipitation, temperature, and precipitation type data from 1985 to 2018 were used. For the three scenarios RCP2.6, RCP4.5, and RCP8.5, the National Center for Environmental Protection's (NCEP) atmospheric reanalysis data and the CanESM2 model were used to forecast future climate change. Furthermore, the downscaling was done using the SDSM5.3 model. To find data patterns, the classic and modified Mann-Kendall tests were performed. Fixed temperature approaches, the UBC watershed model, the USCE model, and Kienzel's suggested method were utilized to separate the precipitation phase. Results: To separate the precipitation phase throughout the fundamental period, observational reports were examined, and the approaches Kienzle and USCE gave satisfactory results. Climate change will also produce major changes in the precipitation temperature distribution in the examined mountain region in the future, according to the findings of this study. Also, a significant portion of the influence of climate change on the snow and rain phases. The modifications are done in such a way that rainfall will rise at higher temperatures and decrease at lower temperatures in the prediction period (2026-2060) compared to the observation period (1985-2018). The greatest total rainfall recorded at Shahrekord station during the observation period was 5.7 °C, which has fallen to 0 °C in the projected period. The temperature range of precipitation at this station was -10 to +18 degrees Celsius during the observation period, and will climb to an average of -10 to +24 degrees Celsius for all three scenarios over the forecast period. The range of precipitation in the future and measurements at Koohrang station is essentially the same, but climate change has produced a rapid shift in the amount of precipitation in this temperature range. Over example, during the 34-year observation period, the greatest rainfall that occurred at a temperature of 1.6 °C was a total of 5700 mm, which was reduced to -1.6 °C and a value of 3700 mm owing to climate change for the next 34 years. The highest limit of the precipitation range at Boroojen station has increased from +18 °C in the historical era to +24 °C in the anticipated period as a result of the modifications. Conclusion: The results of the trend test on the predicted data demonstrate that it is present in the monthly rainfall in the study stations in a substantial way. The temperature distribution of precipitation varies as a result of these changes, which are caused by the impacts of climate change on the study region. [ABSTRACT FROM AUTHOR]

This study presents results from regular observation of permanent and summer-persisting firn-ice bodies in the highest parts of the Dinaric Alps. The sizes of six small glaciers and two snow patches on the Prokletije Massif (in Albania) and the Durmitor Massif (in Montenegro) were measured from 2011 to 2018. In recent years, specific cycles of interannual behavior have been observed: a year of considerable snow accumulation (a »recharge« phase), followed by two to four years of gradual decrease (a »wastage« phase). At present, the small glaciers studied exist in unbalanced conditions, which in the long term may lead to their degradation. Progressive warming makes short-term cycle minimums increasingly severe. Their retreat after the summer of 2017 was probably the most pronounced since the Little Ice Age, and small glaciers are on the verge of extinction.

According to the forecast of IPCC (Intergovernmental Panel of the Climate Change), an increase in precipitation is expected in this century in the Arctic. The main reason is intensification of evaporation from waters of the Arctic Ocean opening due to the intensive melting of sea ice. It is supposed that these changes will be most severe in winters in the Arctic regions, which are subject to significant anthropogenic load. In this respect, the intensively developed Nadym Lowland may be considered as a promising area for researches. The results of our study showed that the circulation conditions (primarily cyclones coming from the North Atlantic under the Eastern (E) circulation form of the G.Ya. Vangenheim–A.A. Girs classification) significantly influence on the isotopic composition of precipitation in this region. Thus, in the cold period of 2016–2017, the isotopic composition of precipitation changed for δ18О by 21 ‰, and for δD by 167 ‰ (weighted average values δ18О = −22.3 ‰, δD = −172.6 ‰, and dexc = 5.6 ‰). The use of the dew point temperature at the moment of precipitation in the calculations of the isotopic-temperature dependences allows obtaining the following coupling equation: δ18О = 0.67Tdp − 15.2 (R2 = 0.67). On the basis of the joint analysis of synoptic, trajectory and isotopic data, the main regions-sources of atmospheric moisture, precipitated in the Nadym Lowland during the cold period of 2016–2017, were determined. The major contributions were made by the Atlantic Ocean (35.7%), the North Atlantic Ocean and the Arctic Ocean (30.4%), and the Black Sea-Caspian region (20%). The last one is characterized by the most weighted isotopic composition. Inland source regions have contributed the least to precipitation (slightly larger 10%), and their lightweight isotopic composition is related to cryogenic fractionation.

The India–Burma troughs (IBTs) with different shapes (i.e., narrow and wide IBT-like circulations) can significantly affect winter precipitation over different regions in southern China through modulating the paths of water vapor transportation ahead of the IBTs. The effect of the wide/narrow IBT- (WIBT/NIBT-) like circulation cannot be depicted by traditional IBT indices that mainly focus on the IBT's intensity. This study defines the WIBT and NIBT indices, which can effectively distinguish different water vapor transportation in front of the WIBT and NIBT and relevant water vapor convergence and therefore successfully reflect different distributions of winter precipitation anomalies over southern China. Further exploration reveals that a Rossby wave from the Mediterranean Sea to the Bay of Bengal (BoB) contributes to the variability of the NIBT, while the El Niño–Southern Oscillation (ENSO) can modulate the variability of the WIBT by stimulating the Matsuno–Gill response. The WIBT and NIBT indices should be considered as important supplements to the traditional IBT indices, which are favorable to more detailed diagnosis and prediction of winter climate over southern China. [ABSTRACT FROM AUTHOR]

This study reveals an intensified impact of winter (November–February mean) Arctic Oscillation (AO) on simultaneous precipitation over the mid–high latitudes of Asia (MHA) since the early 2000s. The unstable relationship may be related to the changes in the tropospheric AO mode and the subtropical jet. Further analyses suggest that their changes may be attributable to the interdecadal changes in the stratospheric polar vortex. During 2002–2017, the anomalously weak stratospheric polar vortex is accompanied by intensified upward-propagating tropospheric planetary-scale waves anomalies. Subsequently, the stratospheric geopotential height anomalies over the North Atlantic high-latitudes propagate downward strongly, causing the changes in the tropospheric AO mode, that is, the positive height anomalies over the North Atlantic high-latitudes are stronger and extend southward, corresponding to the stronger and eastward extension of negative height anomalies over the North Atlantic mid-latitudes. Thus, the Rossby wave source anomalies over Baffin Bay and the Black Sea are strong, and correspondingly so too are their subsequently excited the Rossby waves anomalies. Meanwhile, the planetary-scale waves anomalies propagate weakly along the low-latitude waveguide, causing the intensified and southward shift of the subtropical jet. Therefore, the strong Rossby waves anomalies propagate eastward to the MHA. By contrast, during 1979–1999, the strong stratospheric polar vortex anomaly is accompanied by weak upward-propagating planetary-scale waves anomalies, resulting in weaker height anomalies over the North Atlantic mid–high latitudes. Consequently, the anomalous Rossby waves are weak. In addition, the subtropical jet weakens and shifts northward, which causes the Rossby waves anomalies to dominate over the North Atlantic, and thereby the impact of winter AO on simultaneous precipitation over the MHA is weak.

Low-elevation mountains represent unique model systems to study species endangered by climate warming, such as subalpine and alpine species of butterflies. We aimed to test the effect of climate variables experienced by Erebia butterflies during their development on adult abundances and phenology, targeting the key climate factors determining the population dynamics of mountain insects. We analysed data from a long-term monitoring of adults of two subalpine and alpine butterfly species, Erebia epiphron and E. sudetica (Nymphalidae: Satyrinae) in the Jeseník Mts and Krkonoše Mts (Czech Republic). Our data revealed consistent patterns in their responses to climatic conditions. Lower precipitation (i.e., less snow cover) experienced by overwintering larvae decreases subsequent adult abundances. Conversely, warmer autumns and warmer and drier springs during the active larval phase increase adult abundances and lead to earlier onset and extended duration of the flight season. The population trends of these mountain butterflies are stable or even increasing. On the background of generally increasing temperatures within the mountain ranges, population stability indicates dynamic equilibrium of positive and detrimental consequences of climate warming among different life history stages. These contradictory effects warn against simplistic predictions of climate change consequences on mountain species based only on predicted increases in average temperature. Microclimate variability may facilitate the survival of mountain insect populations, however the availability of suitable habitats will strongly depend on the management of mountain grasslands. [ABSTRACT FROM AUTHOR]

Prediction of winter precipitation is challenging because besides its amount also its variable phase might have a strong impact on people, transportation, and infrastructure in general. We combine a bulk microphysics numerical weather prediction with a 1D spectral bin microphysical model, which explicitely treats the processes of melting, ice nucleation and refreezing as a first step towards a potential nowcasting application. Polarimetric weather radar observations from the German national meteorological service (DWD) are used to evaluate the approach. The potential of the strategy is demonstrated by its application to the black ice event occurring in Berlin, Germany, on 20 January 2014. The methodology is able to clearly identify the classical mechanism leading to freezing rain at the surface, which might be exploited in future nowcasting algorithms.

Over the past three decades, several general circulation models of the atmosphere and ocean (atmospheric and oceanic general circulation models – GCMs) have been improved by modeling the hydrological cycle with the use of isotopologues (isotopes of water) HDO and H2 18O. Input parameters for the GCM models taking into account changes in the isotope composition of atmospheric precipitation were, above all, the results obtained by the network GNIP – Global Network of Isotopes in Precipitation. At different times, on the vast territory of Russia there were only about 40 simultaneously functioning stations where the sampling of atmospheric precipitation was performed. In this study we present the results of the isotope composition of samples taken on the foothills of the Altai during two winter seasons of 2014/15 and 2015/16. Values of the isotope composition of precipitation changed in a wide range and their maximum fluctuations were 25, 202 and 18‰ for δ18О, dexc and δD, respectively. The weighted-mean values of δ18О and δD of the precipitation analyzed for the above two seasons were close to each other (−21.1 and −158.1‰ for the first season and −21.1 and −161.9‰ for the second one), while dexc values differed significantly. The comparison of the results of isotope analysis of the snow cover integral samples with the corresponding in the time interval the weighted-mean values of precipitation showed high consistency. However, despite the similarity of values of δ18О and δD, calculated for precipitation and snow cover, and the results, interpolated in IsoMAP (from data of the GNIP stations for 1960–2010), the dexc values were close to mean annual values of IsoMAP for only the second winter season. According to the trajectory analysis (the HYSPLIT model), the revealed differences between both, the seasons, and the long-term average values of IsoMAP, were associated with a change of main regions where the air masses carrying precipitation were formed, namely, the North Atlantic (the winter season of 2014/15) and the inland areas with open ice-free water bodies (the season of 2015/16). Thus, with the correct interpretation of the results, the data on the snow cover isotope composition on the Altai foothills can be used as an alternative data sources instead of the GNIP data.

Urban modification of precipitation regimes is well documented in the urban climate literature. Studies investigating urbanization and non-convective precipitation, specifically winter precipitation, are limited. The theoretical framework here argues that the collective influence of urbanization extends beyond traditional city limits and the surrounding rural areas and can impact regional climate in non-adjacent cities. This paper utilizes the weather research and forecasting model (WRF-ARW) to simulate a cold-season synoptic system over the Northeastern United States over a variety of urban land surface scenarios. This case study centers on the potential boundary layer urban heat island effect on the lower troposphere and its ability to impact winter precipitation type at the local to regional scales. Results show a significant reduction in temperatures near the modified surface and subtle reductions over adjacent urban areas. When surface wind speeds are less than 5 ms−1, the boundary layer heat island increases air temperatures on the order of 3–4 °C at altitudes up to 925 mb. When combined with encroaching warm air near 850 mb during transitional precipitation events, the boundary layer heat island increases the thickness of the melting layer and consequently exposes falling hydrometeors to longer melting duration and phase change. Model simulations also show regional connections through remote temperature and relative humidity changes in urban areas removed from reforested areas.

Previous investigations have reported that the impacts of the preceding climate signal in the Southern Hemisphere can extend to Northern Hemisphere middle latitudes during the following season. This study suggests that the positive (negative) boreal autumn south Pacific Ocean dipole (SPOD) sea surface temperature anomalies are usually followed by reduced (increased) precipitation in the following winter over the North American monsoon (NAM) region. The positive autumn SPOD has the potential to regulate the southward fluctuation of the eddy-driven westerly jet in the southern Pacific Ocean, and exert the Rossby wave train stretching across the Pacific Ocean to transport the related energy into the NAM region. This finally results in anomalous high pressure in the troposphere over the NAM region. The related sinking motion and the water vapor conditions further affect the precipitation variability in these regions. This entire process can be referred to as a “coupled oceanic–atmospheric bridge”, in which the “oceanic bridge” is the SPOD and the “atmospheric bridge” is the response of atmospheric circulation in the Pacific Ocean.

Winter (December, January, and February (DJF)) precipitation over northwest India (NWI) is mainly associated with the eastward moving mid-latitude synoptic systems, western disturbances (WDs), embedded within the subtropical westerly jet (SWJ), and is crucial for Rabi (DJF) crops. In this study, the role of winter precipitation at seasonal and monthly scale over NWI and its nine meteorological subdivisions has been analyzed. High-resolution (0.25° × 0.25°) gridded precipitation data set of India Meteorological Department (IMD) for the period of 1901-2013 is used. Results indicated that the seasonal precipitation over NWI is below (above) the long-term mean in most of the years, when precipitation in any of the month (December/January/February) is in deficit (excess). The contribution of December precipitation (15-20%) to the seasonal (DJF) precipitation is lesser than January (35-40%) and February (35-50%) over all the subdivisions. December (0.60), January (0.57), and February (0.69) precipitation is in-phase (correlation) with the corresponding winter season precipitation. However, January precipitation is not in-phase with the corresponding December (0.083) and February (−0.03) precipitation, while December is in-phase with the February (0.21). When monthly precipitation (December or January or December-January or February) at subdivision level over NWI is excess (deficit); then, the probability of occurrence of seasonal excess (deficit) precipitation is high (almost nil). When antecedent-monthly precipitation is a deficit or excess, the probability of monthly (January or February or January + February) precipitation to be a normal category is >60% over all the subdivisions. This study concludes that the December precipitation is a good indicator to estimate the performance of January, February, January-February, and the seasonal (DJF) precipitation. [ABSTRACT FROM AUTHOR]

Both the El Niño Southern Oscillation (ENSO) and subtropical Indian Ocean Dipole (SIOD) have significant impacts on the winter precipitation over southern China (SC). In this study, we investigate the synergistic effect of ENSO and SIOD on southern China winter precipitation (SCWP). Our findings indicate that SCWP is closely associated with the out-of-phase configurations of ENSO and SIOD, with precipitation tending to increase (decrease) during El Niño and negative SIOD (La Niña and positive SIOD). During El Niño and negative SIOD, the El Niño leads to an anomalous anticyclone over the northwest Pacific through Walker circulation and Gill-type tropical response. The associated southwesterly winds of the anticyclone transport ample water vapor towards SC. The El Niño and negative SIOD both trigger a wave-like pattern from Europe to SC. This wave train (PC1-like wave train) propagates towards SC and induces anomalous cyclonic circulation and strong upward motion over SC, resulting in enhanced precipitation over SC. During La Niña and positive SIOD, the low-level cyclone over the northwest Pacific results from both La Niña and positive SIOD. The positive SIOD enhances La Niña-related cyclonic circulation response through cross-equator Hadley circulation, weakening the water vapor transport towards SC. The positive SIOD-related wave train (PC3-like wave train) plays the dominant role in inducing anomalous anticyclonic circulation and weak descending motion, leading to reduced precipitation over SC. • ENSO and SIOD have a synergistic effect on the winter precipitation over southern China. • The out-of-phase configurations of ENSO and SIOD are strongly associated with the winter precipitation over southern China. • El Niño and negative SIOD (La Niña and positive SIOD) mainly lead to anomalous vertical motions (water vapor transport). [ABSTRACT FROM AUTHOR]

In the present study we estimate the velocity and thickness of the Patseo glacier, Himachal Pradesh, India. The average velocity of the glacier was estimated as ~5.47 m/year using co-registration of optically sensed images and correlation (COSI-Corr) method. The glacier thickness was found to vary between 12 and 278 m, with an average value 59 m. The total glacier ice volume was estimated as ~15.8 × 107 m3, with equivalent water reservoir of ~14.5 × 107 m3. Ground penetrating radar (GPR) surveys were conducted during 2004 and 2013 for validation of the estimated glacier thickness. The glacier thickness estimated using COSI-Corr method was found to be in agreement with GPR-retrieved glacier thickness (RMSE = 4.75 m; MAE = 3.74 m). The GPR profiles collected along the same geographic locations on the glacier during 2004 and 2013 showed a reduction in ice thickness of ~1.89 m, and thus resulting in an annual ice thickness decrease of ~0.21 m. The glacier area was estimated for 2004 and 2013 using LISS IV satellite data and found to be ~2.52 and ~2.30 sq. km respectively. This shows an annual reduction of ~0.024 sq. km in glacier area. The total annual loss in glacier ice volume was estimated as ~4.55 × 105 m3. This loss in the glacier ice volume of the Patseo glacier is supported by the snow and meteorological observations collected at a nearby field observatory of Snow and Avalanche Study Establishment (SASE). The climate data collected at SASE meteorological observatory at Patseo (3800 m), between 1993-94 and 2014-15 showed an increasing trend in the mean annual temperature and a decreasing trend in winter precipitation. [ABSTRACT FROM AUTHOR]

Using ERA-interim Reanalysis data and observational data, the intraseasonal oscillation of the winter rainfall in southern China is studied. The mean square deviation of daily precipitation is used to express precipitation variability, and winter precipitation variability over southern China is determined to be highly correlated with sea surface temperature (SST) in central and eastern tropical Pacific; the dominant period of the precipitation is 10–30 days, which reflects quasi-biweekly oscillation. Examination of 1000 hPa geopotential height suggests that key low-pressure systems affecting the intraseasonal precipitation come from Lake Baikal, but with different travel paths. In El Niño years, key low-pressure systems converge with other low-pressure systems and move southeastward until reaching South China, while in La Niña years, only one low-pressure system can reach southern China. Meanwhile, the explosive development of the low-pressure system is mainly caused by the joint effects of thermal advection and vorticity advection in El Niño, and only vorticity advection accounted for the dominant status in La Niña. Multiscale analysis shows that the meridional distribution of intraseasonal circulation plays an important role on the thermal transmission and brings strong warm advection from low latitudes to high latitudes in El Niño.

Winter precipitation over South China tended to be much higher than normal for the spring El Niño events during 1979–2016. For the spring El Niño events, the meridional and zonal circulations served as a bridge, linking the warmer sea surface temperature (SST) in the eastern equatorial Pacific (EEP) and South China winter precipitation. This possible physical process can be described as follows: During boreal winter, a positive SST anomaly in the EEP was concurrent with strong anomalous convection activity over South China via anomalous Walker circulation, an anomalous Hadley Cell along 110°–130° E, and a zonal westward teleconnection wave train pattern at 700 hPa in the Northern Hemisphere. In addition, an anomalous pumping effect at 200 hPa contributed to the convective activity. Meanwhile, the western Pacific subtropical high moved southwards and strengthened at 500 hPa, and abnormal southwesterly winds brought plentiful water vapor to South China at 850 hPa. All these factors favored an increase in precipitation over South China. For the summer El Niño events, the aforementioned anomalies were weaker, which resulted in a precipitation close to normal over South China.

The current work investigated the impact of the interannual variation in the autumn-winter snow cover extent (SCE) over the extratropical Eurasian continent on Northeast Asian winter precipitation (NAWP) using observational data from 1972 to 2019. The leading singular value decomposition (SVD) mode of the interannual variation in the NAWP is significantly related to autumn SCE anomalies over Central Asia (SCE_CA), with decreased autumn SCE_CA corresponding to increased NAWP. The possible mechanisms responsible for this autumn SCE_CA-NAWP relationship are examined. The analytical results show that the reduced autumn SCE_CA has a significant warming effect on the overlying atmosphere and induces an anomalous anticyclone over CA. This anticyclonic response cooperates with the North Atlantic sea surface temperature anomaly (SST)-generated atmospheric wave pattern, promoting a further eastward extension of the wave pattern to the downstream regions of the Eurasian continent. The anomalous autumn SCE_CA can persist to the following winter, and its related atmospheric wave train is maintained and further strengthened by the increased winter SCE over North China (SCE_NC). In winter, the atmospheric circulation features a pronounced low-pressure system over Northeast Asia and a high-pressure system over the western North Pacific sector. The anomalous southeasterly winds between these two systems transport water vapor from the lower-latitude Pacific Ocean to the interior of the continent, accounting for more NAWP. A composite analysis further indicates that this autumn SCE_CA-NAWP relationship is primarily independent of the North Atlantic SSTs. • There is a significant negative correlation between the autumn SCE anomalies over Central Asia (SCE_CA) and Northeast Asian winter precipitation (NAWP). • The critical system linking the SCE_CA-NAWP is a continental-scale atmospheric wave pattern originating from the North Atlantic and reaching North Pacific. • The autumn SCE over CA and winter SCE over North China are essential in maintaining and propagating the continental-scale atmospheric wave pattern. [ABSTRACT FROM AUTHOR]

This article proposes and presents a novel approach to the characterization of winter precipitation and modeling of radar observables through a synergistic use of advanced optical disdrometers for microphysical and geometrical measurements of ice and snow particles (in particular, a multi-angle snowflake camera—MASC), image processing methodology, advanced method-of-moments scattering computations, and state-of-the-art polarimetric radars. The article also describes the newly built and established MASCRAD (MASC + Radar) in-situ measurement site, under the umbrella of CSU-CHILL Radar, as well as the MASCRAD project and 2014/2015 winter campaign. We apply a visual hull method to reconstruct 3D shapes of ice particles based on high-resolution MASC images, and perform "particle-by-particle" scattering computations to obtain polarimetric radar observables. The article also presents and discusses selected illustrative observation data, results, and analyses for three cases with widely-differing meteorological settings that involve contrasting hydrometeor forms. Illustrative results of scattering calculations based on MASC images captured during these events, in comparison with radar data, as well as selected comparative studies of snow habits from MASC, 2D video-disdrometer, and CHILL radar data, are presented, along with the analysis of microphysical characteristics of particles. In the longer term, this work has potential to significantly improve the radar-based quantitative winter-precipitation estimation. [ABSTRACT FROM AUTHOR]

This study discovered a decreasing phenomenon of interdecadal variation in winter precipitation averaged over southern China since 1998. This study analyzed the difference in the average precipitation in the periods of 1999-2014 and 1980-1998 to determine the cause of reduction in winter precipitation in recent years. The spatial distribution of difference in winter precipitation between the two periods showed that negative anomalies were distributed from the equatorial eastern Pacific to the equatorial central Pacific, whereas positive anomalies were distributed in the subtropical western Pacific, Maritime Continent, and northern part of Australia. This pattern is a typical spatial distribution of precipitation anomalies displayed at La Niña events. On the other hand, most of the northern parts (i.e., above 20°N) in East Asia showed negative anomalies, the centers of which were distributed over southern China. To determine the characteristic of the large-scale atmospheric circulations that caused a difference of spatial distribution in precipitation between the two periods, a difference in 850 hPa streamlines was analyzed between the two periods. In the tropical Pacific, the Walker circulation, in which air ascended from the Maritime Continent and tropical western Pacific and descended at the equatorial central Pacific, was strengthened. Thus, this was caused by a spatial distribution of sea surface temperature, La Niña-like pattern. In the East Asia region, the Hadley circulation, in which air ascended at the southern China Sea and descended at mid-latitude regions in East Asia, was strengthened. This circulation was related to an anomalous pressure system pattern of the west high east low type in East Asia and the strengthening of the East Asian winter monsoon, which can be confirmed through the snow depth, which increased in mid-latitude regions in East Asia in recent years. [ABSTRACT FROM AUTHOR]

This study investigated the interdecadal variations in winter precipitation over the nonmonsoonal Eurasian regions (30°-70°N, 0°-80°E) (NER) and possible contributions of the Arctic sea ice for the period 1948‐2019. The dominant mode of the interdecadal variations in winter precipitation over NER (DM_NWPE) features opposite loading over the Mediterranean region and over the northern NER and Central Asia. The positive phase of DM_NWPE with enhanced precipitation over the Mediterranean region and suppressed precipitation over the northern NER and central Asia is associated with positive height anomalies over the high-latitude North Atlantic and Eurasia and negative height anomalies extending from the subtropical North Atlantic Ocean to western Eurasia. Increased sea ice in the Barents Sea may promote an atmospheric wave pattern extending to the downstream Eurasian regions, contributing to decreased precipitation over northern NER and Central Asia. Reduced sea ice in the Baffin Bay-Davis Strait-Labrador Sea (BDL) can promote a southeastward atmospheric wave pattern, contributing to enhanced precipitation over the Mediterranean region. The atmospheric response to the Arctic sea ice forcing is confirmed by experiments with a linear baroclinic model. A dipole pattern of sea surface temperature (SST) anomalies in the North Atlantic Ocean may contribute to the interdecadal variation in DM_NWPE. Further analysis showed that the Arctic sea ice-DM_NWPE relationship is primarily SST independent and the Arctic sea ice plays a more critical role in DM_NWPE variations than the North Atlantic SST anomalies. • The NWPE interdecadal variations feature the opposite variation of precipitation over the Mediterranean and the northern NER–Central Asia. • The increased sea ice in the Barents Sea and reduced sea ice in BDL contribute to the dominant mode of the NWPE interdecadal variations. • The Arctic sea ice plays a more critical role than the North Atlantic SST anomalies in the NWPE interdecadal variations. [ABSTRACT FROM AUTHOR]

Based on monthly rainfall station data from the National Climate Prediction Center of China Meteorological Administration, reanalysis monthly data from NCEP/NCAR including the monthly mean and long-term mean values for geopotential height, winds of multi-levels, NOAA(National Oceanic and Atmospheric Administration) monthly Sea Surface Temperature (ERSSTV5), the causes of anomalous excessive precipitation in 2021/2022 winter over South China (SC) are investigated by Liang-Kleeman information flow, composite and wave flux methods. The results show that the winter precipitation over SC in 2021/2022 DJF is far more than normal, and the associated circulation patterns are obviously different from those induced by traditional La Niña, especially in the Atlantic and East Asia areas south to Lake Baikal. In 2021/2022 DJF, the Tibet Plateau (TP) exists anomalous cyclone with strong ascending motion, which directly affects the circulation patterns in Eastern China and thus the precipitation in SC. It is a significant causal relationship for the earlier season velocity potential at 850 hPa (related to the anomalous SST) over the tropical Atlantic to later DJF anomalous vertical motions over TP. Especially when the anomalies in tropical Atlantic leads one month before, the relationship is closest. The anomalies of the tropical Atlantic can stimulate the Rossby wave train which propagates downstream, corresponding to the abnormal cyclonic circulation over TP. In the early autumn to winter of 2021/2022, the 850 hPa potential velocity anomalies in the tropical Atlantic were significant with positive phase. The Rossby wave train excited by the potential velocity anomalies and then propagated along the great circle path and global jet stream (GJT) over South Asia (SA), formed an anomalous cyclonic with ascending motion over TP and lead more precipitation over SC in winter of 2021/2022. Winter rainfall, usually accompanying with lower temperature, will bring severely bad influence on traffic, power supply, communication, agriculture and people's lives. The results of this paper can provide a reference for further understanding the causes and mechanism of DJF rainfall over SC. • The winter precipitation over SC in 2021/2022 DJF is extremely more than normal, and the associated circulation patterns are obviously different from those induced by La Niña, especially in the Atlantic and East Asia areas south to Lake Baikal. • Strong ascending motion over TP(Tibet Plateau) affects the circulation patterns directly in eastern China and lead to the excessive precipitation in SC during 2021/2022 DJF. • The anomalies over the tropical Atlantic can stimulate the Rossby wave train and propagate downstream, and the Rossby wave trains allow energy to propagate to TP area with wave flux convergent, contributing certainly to the anomaly cyclone circulation there. [ABSTRACT FROM AUTHOR]

Southern China experiences large year-to-year variability in the amount of winter precipitation, which can result in severe social and economic impacts. In this study, we demonstrate prediction skill of southern China winter precipitation by three operational seasonal prediction models: the operational Global seasonal forecasting system version 5 (GloSea5), the NCEP Climate Forecast System (CFSv2) and the Beijing Climate Center Climate System Model (BCC-CSM1.1m). The correlation scores reach 0.76 and 0.67 in GloSea5 and CFSv2, respectively; and the amplitude of the ensemble mean forecast signal is comparable to the observed variations. The skilful predictions in GloSea5 and CFSv2 mainly benefit from the successful representation of the observed ENSO teleconnection. El Niño weakens the Walker circulation and leads to the strengthening of the subtropical high over the northwestern Pacific. The anti-cyclone then induces anomalous northward flow over the South China Sea and brings water vapor to southern China, resulting in more precipitation. This teleconnection pattern is too weak in BCC-CSM1.1m, which explains its low skill (0.13). Whereas the most skilful forecast system is also able to simulate the influence of the Indian Ocean on southern China precipitation via changes in southwesterly winds over the Bay of Bengal. Finally, we examine the real-time forecast for 2015/16 winter when a strong El Niño event led to the highest rainfall over southern China in recent decades. We find that the GloSea5 system gave good advice as it produced the third wettest southern China in the hindcast, but underestimated the observed amplitude. This is likely due to the underestimation of the Siberian High strength in 2015/2016 winter, which has driven strong convergence over southern China. We conclude that some current seasonal forecast systems can give useful warning of impending extremes. However, there is still need for further model improvement to fully represent the complex dynamics of the region.

The study conducted using 20 years total winter precipitation and snowfall data of Shimla (Himachal Pradesh) for winter season (December to March) shows that the total precipitation and snowfall for all the months have a decreasing tendency, the highest being for the month of January. The total precipitation and snowfall for different months were found to have decreased in the second decade under study by 6 to 36% and 16 to 86%, respectively. The beginning of snowfall season did not show any delay. However the season is tending to end earlier by about 12 days per decade. The decadal analysis shows that the average date of ending of the snowfall season has advanced by two weeks in the second decade compared to the first decade. The analysis indicates a potential adverse impact on the river flow and agricultural/horticultural production in Himachal Pradesh and other states down stream.

Ancient blue oak trees are still widespread across the foothills of the Coast Ranges, Cascades, and Sierra Nevada in California. The most extensive tracts of intact old-growth blue oak woodland appear to survive on rugged and remote terrain in the southern Coast Ranges and on the foothills west and southwest of Mt. Lassen. In the authors' sampling of old-growth stands,most blue oak appear to have recruited to the canopy in the middle to late nineteenth century. The oldest living blue oak tree sampled was over 459 years old, and several dead blue oak logs had over 500 annual rings. Precipitation sensitive tree-ring chronologies up to 700 years long have been developed from old blue oak trees and logs. Annual ring-width chronologies of blue oak are strongly correlated with cool season precipitation totals, streamflow in the major rivers of California, and the estuarine water quality of San Francisco Bay. A new network of 36 blue oak chronologies records spatial anomalies in growth that arise from latitudinal changes in the mean storm track and location of land-falling atmospheric rivers. These long, climate-sensitive blue oak chronologies have been used to reconstruct hydroclimatic history in California and will help to better understand and manage water resources. The environmental history embedded in blue oak growth chronologies may help justify efforts to conserve these authentic old-growth native woodlands. [ABSTRACT FROM AUTHOR]

This study analyses the decadal changes in winter precipitation and extreme precipitation in a warming environment in China. The results show that, together with a trend of winter warming in China, winter precipitation and extreme precipitation in the region are also increasing. In addition, concurrent with the decadal warming shift that occurred in the mid-1980s, precipitation and extreme precipitation both increased significantly. Quantitative analysis shows that precipitation and extreme precipitation increased at rates of 9.7% and 22.6% per 1°C of surface warming in China. This rate of precipitation increase is greater than the global mean, which indicates that precipitation in China is highly sensitive to climate warming and further highlights the importance of studying regional responses to climate warming. The fact that extreme precipitation is increasing at a higher rate than precipitation implies that winter precipitation in China will increasingly be of more extreme type in the context of global warming, which could partly explain why there have recently been a number of record-breaking extreme snowfall events in China. [ABSTRACT FROM AUTHOR]

Frequent winter snowstorms have recently caused large economic losses and attracted wide attention. These snowstorms have raised an important scientific question. Under scenarios of future global warming, will winter precipitation in China increase significantly and produce more snow in the north? Using Coupled Model Intercomparison Project phase 3 (CMIP 3) model projections under the Special Report on Emissions Scenario A1B scenario, we generated a possible future Arctic condition, the summer (September) 'ice-free Arctic' condition. We then used corresponding monthly sea surface temperature (SST) values and a set of CO concentrations to drive an atmospheric general circulation model (AGCM), for simulating East Asian climate change. The experimental results show that during the boreal winter (December-January-February; DJF), global surface air temperature would increase significantly under this scenario, producing substantial warming in Arctic regions and at high latitudes in Asia and North America. The Siberian High, Aleutian Low and East Asian winter monsoon would all weaken. However, because of increased transport of water vapor to China from the north, winter precipitation would increase from south to north. In addition, the significant increase in winter temperature might cause fewer cold surges. [ABSTRACT FROM AUTHOR]