Negative Trend In Precipitation Research Articles

The Effects of Climate Change on Normalized Difference Vegetation Index (NDVI) in the Al-Hawizeh Marsh

This study aims to classify Landsat 7,8 satellite data using Normalized Difference Vegetation Index (NDVI) thresholds. Initially, visible and near infrared bands of Landsat 8 satellite were used to derive (NDVI) image. Vegetation, non-vegetation and water areas were then analyzed where thresholds for separating them are carefully determined with the aid of ground truth information of the study area. Also, The Mann-Kendall test was conducted to analyze the trend of temperature and precipitation in the study area. The results of the analysis showed a positive trend with an increase in temperature. On the contrary, a negative trend in precipitation remained constant, as it was not statistically significant. The study correlated the historical trends of climatic elements as a central factor in the degradation of swamps (vegetation cover) from 2000 to 2010 and (2015-2023). The results showed that the year 2015 witnessed an increase in the area of NDVI compared to the years studied, as the total area of vegetation cover during this year amounted to about 537.47 km2, by 79.4%. While the year 2023 was one of the worst years of the study area, as the marshes witnessed an increase in the area of dry lands at the expense of the marsh waters, as the area of these lands reached about 354.69 km2 by 52.40%. The findings of this study are that the application of the three indices is useful for evaluating land, especially NDVI in wetlands. So it is necessary to develop and integrate with other remote sensing indices.

Seasonal precipitation changes in the western Mediterranean Basin: The case of the Spanish mainland, 1916–2015

AbstractThis study examines the spatial and temporal variations in seasonal precipitation patterns across the Spanish mainland, within the western Mediterranean Basin, spanning the years 1916–2015. Utilizing the recently developed MOPREDAS_century database at a 10 × 10 km grid resolution, our analysis reveals predominantly negative trends in precipitation across the study area over the entire period, primarily driven by declines in spring precipitation, with lesser decreases in summer and winter. Notably, these trends exhibit complexity, manifesting as two distinct pulses occurring roughly at the outset and conclusion of the 20th century. However, upon employing a moving windows analysis, we find that since the mid‐1970s, seasonal precipitation trends have largely been nonsignificant. Spatially, the precipitation regime across 1916–2015 delineates three primary zones: a winter‐maximum zone in the north, an autumn‐maximum zone along the eastern coast, and a transition from winter‐maximum to spring‐maximum towards the western and inland regions. Noteworthy shifts in this spatial distribution are evident over the four 25‐year intervals examined. Initially, during 1916–1940, winter, autumn and spring regimes occupied 44.1%, 24.2% and 31.7% of the land, respectively. Subsequently, in the periods 1941–1965 and 1966–1990, winter dominance expanded to over 50% of the grid area, while spring varied between 34.7% and 25.5%, and autumn decreased notably to 12.4% and 13.5%. Lastly, significant alterations occurred in the final period of 1991–2015, with winter coverage decreasing to 33.7%, spring to 15.8% and autumn expanding to 50.1% of the grid area. In summary, the prevalent winter and spring regimes at the dawn of the 20th century have transitioned towards an autumn‐dominated regime, particularly in much of the central and western Spanish mainland, with these shifts possibly linked to the evolving precipitation trends. These findings contribute novel insights, particularly pre‐1950, and align with published results post‐1950 across the Mediterranean, particularly in its western regions. Furthermore, they suggest a potential connection between changes in the spatial distribution of seasonal precipitation regimes and temporal variations in the primary moisture sources over the study area.

Homogeneous regions of precipitation trends across the Amazon River Basin, determined from the Global Precipitation Climatology Centre - GPCC

Space-temporal patterns of precipitation are influenced by complex interactions between changes in climate and land cover. The Amazon River Basin has local and global impacts regarding the hydrological cycle; therefore, it is critical to understand how precipitation patterns and intensity are changing. The objective of this study was to analyze precipitation trends and form homogeneous regions of precipitation trends in the Amazon River Basin using the data set of precipitation data from the meteorological satellite Global Precipitation Climatology Center (GPCC), applying non-parametric methods (Mann-Kendall, Spearman and Sen slope) and fuzzy C-means to identify specific regions that are experiencing changes in hydrological patterns. The results show changes in rainfall behavior over time and in the intensity of events. The statistics applied to form clusters resulted in 6 well-divided homogeneous groups, each with unique characteristics. Specifically, the central-southern areas of the basin showed negative trends in precipitation (-1.17 mm/year) forming a homogeneous region (HR1), while in the northern region there was an increasing trend in precipitation (2.73 mm/year). In general, over the 37 years studied, the wetlands tended to become wetter and the dry areas drier. Other homogeneous regions presented their own results and unique characteristics, which agree with other studies

Modeling future (2021–2050) meteorological drought characteristics using CMIP6 climate scenarios in the Western Cape Province, South Africa

Consistent drought modelling under plausible shared socioeconomic–representative concentration pathways (SSP–RCPs) are crucial for effectively managing future drought risk in agricultural environments. The Western Cape (WC) is one of South Africa’s main agro-based provinces and faces a mounting threat of water insecurity due to recurrent drought. The objective of this study was to predict meteorological drought hazard for 2021–2050 based on three CMIP6 scenarios: SSP5–8.5, SSP2–4.5 and SSP1–2.6. Precipitation simulations generated by the sixth version of Model for Interdisciplinary Research on Climate (MIROC6) under the SSP5–8.5, SSP2–4.5 and SSP1–2.6 scenarios were used from fifteen stations across the six AEZs of the WC province. The Standardised Precipitation Index (SPI) was computed at 12-month timescales. Trend analysis of precipitation datasets and the SPI-values were done at p < 0.05 using the Mann–Kendall (M–K) test. The findings revealed negative precipitation trends of − 7.6 mm/year in Ceres, while positive trends of 0.3 mm/year were observed in Malmesbury. These findings indicate an improvement from − 7.8 and − 6.4 mm/year in the same regions, respectively, compared to historical trends observed between 1980 and 2020. The results suggest that in 2042 and 2044, Bredasdorp will experience − 2 < SPI < − 1.5 under the SSP2–4.5 scenarios, while Matroosberg in 2038 under the SSP5–8.5 will experience SPI > − 2. The findings of this study will assist in the development of proactive planning and implementation of drought mitigation strategies and policies aimed at reducing water insecurity in AEZs.

Impacts of hydroclimate change on climate-resilient agriculture at the river basin management

Abstract This paper focuses on exploring the potential of Climate resilient agriculture (CRA) for river basin-scale management. Our analysis is based on long-term historical and future climate and hydrological datasets within a GIS environment, focusing on the Ajoy River basin in West Bengal, Eastern India. The standardized anomaly index (SAI) and slope of the linear regression (SLR) methods were employed to analyse the spatial pattern of the climate variables (precipitation, Tmax and Tmin) and hydrological variables (actual evapotranspiration (AET), runoff (Q), vapor pressure deficit (VPD), potential evapotranspiration (PET), and climate water deficit (DEF)) using the TerraClimate dataset spanning from 1958 to 2020. Future climate trend analysis spanning 2021 to 2050 was conducted using the CMIP6 based GCMs (MIROC6 and EC-Earth3) dataset under shared socio-economic pathway (SSP2-4.5, SSP5-8.5 and historical). For spatiotemporal water storage analysis, we relied on Gravity Recovery and Climate Experiment (GRACE) from the Center for Space Research (CSR) and the Jet Propulsion Laboratory (JPL) data, covering the period from 2002 to 2021. Validation was performed using regional groundwater level data, employing various machine learning classification models. Our findings revealed a negative precipitation trend (approximately −0.04 mm/year) in the southern part, whereas the northern part exhibited a positive trend (approximately 0.10 mm/year).

Examining the relationship between vegetation decline and precipitation in the national parks of the Greater Limpopo Transfrontier Conservation Area during the 21st century

The Greater Limpopo Transfrontier Conservation Area (GLTFCA) of southeastern Southern Africa is home to five large national parks and is an important protected area crossing different geopolitical borders, but with the same conservation goals. However, even with similar management techniques, there have been concerning declines in vegetation observed across the last few decades. This study proposes that a larger driver, climate, is linked to this decline over time, and raises the point that these conservation areas are more important now than ever. Precipitation (annual and seasonal), the Normalized Difference Vegetation Index (NDVI, indicator of vegetation health), and Directional Persistence data (D, metric to measure trends in vegetation health over time compared to a baseline value) from 2000 to 2020 are used. Overall, there was a negative trend in precipitation during the 21st century in all seasons except the beginning of the wet season. Linked to this were negative trends in vegetation health both in absolute Normalized Difference Vegetation Index values and resultant D values. Overall, this study found a decline in precipitation, which was significantly linked to a decline in vegetation health across the majority of the year in the Greater Limpopo Transfrontier Conservation Area. This study supports literature on browning in sub-Saharan Africa and gives managers even more reason to work together towards a unified conservation strategy for this important region.

Analysis of recent rainfall trends and links to teleconnection patterns in California (U.S.)

The aim of this research is to enlarge knowledge of space-time evolution of precipitation in California over the last decade on a monthly, seasonal and annual time-scale. This study also analyses the relationship between precipitation and teleconnection patterns with most influence on Californian climate. The homogeneity of the data from the selected stations was verified and finally 165 meteorological stations were used with an observation period that ranged from 1980 to 2019. In order to evaluate trends and statistical significance, both the non-parametric Mann-Kendall test and modified Sen’s slope method were used. Correlation analysis using the partial non-parametric Spearman Test (95% confidence level) was performed to find out relationships between precipitation and nine teleconnection patterns in the State of California. Spatial analysis was achieved using Empirical Bayesian Kriging (EBK). Finally, this research, as a novelty, shows regionalisation of California State as a function of significance in the correlation of precipitation with teleconnection patterns. To achieve this, Principal Component Analysis (PCA) and Agglomerative Hierarchical Cluster analysis (HCA) was performed. Results show a positive precipitation trend in winter and negative precipitation trend in late summer and autumn. The teleconnection patterns more correlated with precipitation are El Niño along Southern Oscillation (ENSO), Antarctic Oscillation (AAO) and North Atlantic Oscillation (NAO). Four areas were discerned outlining the Mojave Climate Region (Area 4) by having ENSO as the teleconnection pattern that best account precipitation.

Contribution of Climate Change and Grazing on Carbon Dynamics in Central Asian Pasturelands

Reducing the uncertainties in carbon balance assessment is essential for better pastureland management in arid areas. Climate forcing data are some of the major uncertainty sources. In this study, a modified Biome-BGC grazing model was driven by an ensemble of reanalysis data of the Climate Forecast System Reanalysis data (CFSR), the European Centre for Medium-Range Weather Forecasts Interim Reanalysis (ERA-Interim), and the Modern-Era Retrospective Analysis for Research and Applications (MERRA), to study the effect of climate change and grazing on the net ecosystem exchange (NEE) of the pasturelands in Central Asia. Afterwards, we evaluated the performance of corresponding climate datasets over four major pastureland types, and quantified the modeling uncertainty induced by climate forcing data. Our results suggest that (1) a significant positive trend in temperature and a negative trend in precipitation were obtained from the three climate datasets. The average precipitation is apparently higher in the CFSR and MERRA data, showing the highest temperature value among the data sets; (2) pasturelands in Central Asia released 2.10 ± 1.60 Pg C in the past 36 years. The highest values were obtained with the CFSR (−1.53 Pg C) and the lowest with the MERRA (−2.35 Pg C) data set; (3) without grazing effects, pasturelands in Central Asia assimilated 0.13 ± 0.06 Pg C from 1981–2014. Grazing activities dominated carbon release (100%), whereas climate changes dominated carbon assimilation (offset 6.22% of all the carbon release). This study offered possible implications to the policy makers and local herdsmen of sustainable management of pastureland and the adaptation of climate change in Central Asia.

Correction to: Changes in spatio-temporal distribution of AgMERRA-derived agro-climatic indices and agro-climatic zones for wheat crops in the northeast Iran

This study evaluates the potential of gridded AgMERRA (the Modern-Era Retrospective Analysis for Research and Applications) to estimate aridity index (AI), growing degree days (GDD), and temperature seasonality (TS) for six land stations across northeast Iran. The researcher investigated the spatiotemporal variation of the AgMERRA-derived agro-climatic indices for the entire period 1981–2010 and three 10-year sub-periods for the 347 wheat harvested grid cells (0.25° × 0.25°) and their utility for agro-climate zoning in northeast Iran. Results indicated a good agreement between AgMERRA daily solar radiation, maximum and minimum temperatures, and annual total precipitation with corresponding land observations for the six studied sites. AgMERRA-derived evapotranspiration (ETo), AI, GDD, and TS also exhibited good agreement (R2 and d > 0.7) with the land station–derived indices for most of the locations. Annual analysis of the AI indicated a negative trend for all of the wheat harvested grid cells, but the decrease was significant (p < 0.05) only for 14.70% of grid cells, which were located in the southwest part of the studied region. The magnitude of the significant decreasing trends in annual AI was (−)0.0011 per year. The increase in aridity was due to the concurrent occurrences of positive ETo trends and negative precipitation trends. All of the wheat harvested grid cells showed a significant increasing trend (p < 0.05) for GDD at the rate of 24.10 °C d year−1. The TS series demonstrated an apparent increasing trend for 99.2% of wheat harvested grid cells; however, only 16.9% of them had the significant positive trend (p < 0.05) with the average rate of 0.023 °C year−1. The wheat harvested grid cells with increasing trend for TS were mainly distributed in the arid mountainous southern part of the study area. The 10 years sub-periods revealed that the best conditions in terms of most of the studied agro-climatic indices were found in sub-period 1981–1990 and the north Khorasan had better conditions in all three sub-periods. Based on AI, GDD, and TS, 13 major gridded agro-climatic zones were recognized in northeast Iran.

Spatio-temporal patterns of wildfires in Siberia during 2001–2020

Siberia is one of the most fire-prone regions of northern Eurasia and also the region with the greatest warming in the Eastern Hemisphere over the last decades. In this study, spatiotemporal features of wildfires in Siberia and their recent trends and relationship with air temperature and precipitation during 2001–2020 were investigated. The main results show that the annual burned area (BA) in Siberia during the study period is 6.5 Mha with a non-significant positive trend (58 kha year−1, p = 0.49), but analysis of the spatial patterns revealed regions with significant trends in BA: negative in the south of Western Siberia (−17 kha year−1, p < 0.05) and positive in the center of Eastern Siberia (10 kha year−1, p < 0.05). Positive trends of BA in Eastern Siberia were accompanied by a positive air temperature trend (0.11 °С year−1) and a negative precipitation trend (–1.64 mm year−1) in June.

Assessing the impact of climate on annual and seasonal discharges at the Sremska Mitrovica station on the Sava River, Serbia

Abstract Flood frequency analysis was performed on annual maxima series for 90 years (1928–2017) of discharge data recorded at the Sremska Mitrovica gauging station on the Sava River. The three-parameter distributions (PearsonIII, Log-PearsonIII) are more suitable for modelling annual maxima than distribution functions with only two parameters (Normal, Log-normal, Gumbel). The Mann–Kendall test statistic indicated that there is no statistically significant trend identified in annual maximum discharges or average annual discharges. A positive increasing trend was observed in annual temperature, while annual precipitation shows a decreasing trend which is non-significant. The seasonality analysis found a statistically non-significant weak negative trend in discharge in spring, summer and autumn and a statistically non-significant weak positive trend in winter. During winter, spring, and summer a non-significant negative trend in precipitation was observed, while autumn has experienced a statistically significant increasing trend. Temperatures show a positive trend in all seasons, but only temperatures during the warm period show a statistically significant increase. The results demonstrate that decreasing discharges of the Sava River at the Sremska Mitrovica gauging station are mainly the consequence of decreasing precipitation and increasing temperature (increasing evaporation), which is consistent with the results of other studies of the region.

Changes in spatio-temporal distribution of AgMERRA-derived agro-climatic indices and agro-climatic zones for wheat crops in the northeast Iran.

This study evaluates the potential of gridded AgMERRA (the Modern-Era Retrospective Analysis for Research and Applications) to estimate aridity index (AI), growing degree days (GDD), and temperature seasonality (TS) for six land stations across northeast Iran. The researcher investigated the spatiotemporal variation of the AgMERRA-derived agro-climatic indices for the entire period 1981-2010 and three 10-year sub-periods for the 347 wheat harvested grid cells (0.25° × 0.25°) and their utility for agro-climate zoning in northeast Iran. Results indicated a good agreement between AgMERRA daily solar radiation, maximum and minimum temperatures, and annual total precipitation with corresponding land observations for the six studied sites. AgMERRA-derived evapotranspiration (ETo), AI, GDD, and TS also exhibited good agreement (R2 and d > 0.7) with the land station-derived indices for most of the locations. Annual analysis of the AI indicated a negative trend for all of the wheat harvested grid cells, but the decrease was significant (p < 0.05) only for 14.70% of grid cells, which were located in the southwest part of the studied region. The magnitude of the significant decreasing trends in annual AI was (-)0.0011 per year. The increase in aridity was due to the concurrent occurrences of positive ETo trends and negative precipitation trends. All of the wheat harvested grid cells showed a significant increasing trend (p < 0.05) for GDD at the rate of 24.10°C d year-1. The TS series demonstrated an apparent increasing trend for 99.2% of wheat harvested grid cells; however, only 16.9% of them had the significant positive trend (p < 0.05) with the average rate of 0.023°Cyear-1. The wheat harvested grid cells with increasing trend for TS were mainly distributed in the arid mountainous southern part of the study area. The 10 years sub-periods revealed that the best conditions in terms of most of the studied agro-climatic indices were found in sub-period 1981-1990 and the north Khorasan had better conditions in all three sub-periods. Based on AI, GDD, and TS, 13 major gridded agro-climatic zones were recognized in northeast Iran.

Differentiated Effects of Urbanization on Precipitation in South China

In this paper, precipitation data from the Tropical Rainfall Measuring Mission (TRMM), together with atmospheric reanalysis data, are employed to identify warm-season precipitation (1998–2014) changes and their association with rapid urbanization in south China. Three urban clusters (Chenyu, Yangtze Delta, and Fujian Guangdong coast) are focused. The results reveal that, for the inland Chengyu urban cluster, a lack of precipitation trend is likely due to insignificant trends in convective available potential energy (CAPE) and total column water vapor (TCWV). They are likely resulted from a reduced local moisture recycling in urban areas, balanced by an increased evapotranspiration of rural areas, together with a stable advection of water vapor input. For the Yangtze River Delta urban cluster, a negative trend in precipitation is associated with a slightly decreased CAPE and an increased TCWV, but is very likely related to urbanization induced an increased planetary boundary layer (PBL) and reduced land surface evaporation. For the Fujian Guangdong coast urban cluster, a marked positive precipitation trend is well explained by positive trends in CAPE and TCWV. The increased precipitation likely benefits from enhanced moisture recycling due to improved vegetation cover in rural areas, and enhanced advection moisture inputs due to urbanization along the coast. These results suggest urbanization effects on precipitation vary with regional conditions. In the coastal area, urbanization enhances sea breezes, which may benefit precipitation if sea breezes go along with the prevailing moisture. In inland area, urbanization likely leads to a warmer-dryer climate if large-scale land cover keeps stationary.

THE IMPACT OF CLIMATE CHANGE ON THE LOSS OF CAPACITY OF THE FOUM EL GHERZA DAM

The study of climate impacts takes on an importance in scientific research, particularly on water resources. The present study highlights the situation of the capacity of Foum El Gherza dam in relation to the observed climate changes. Located in an arid zone of south-eastern Algeria, this dam is a typical example of a region fragile to climate variability. The methodology adopted in this work is based on the analysis of the evolution of the climatic parameters (precipitation and evaporation) as well as the hydrological parameters (flow yields, and leaks) in relation to the losses of stored water volume of the studied dam. The monthly values of climatic and hydrological data contain a 60-year time series (1950 to 2010). The results obtained show that the losses in capacity coincide with the negative trend of precipitation. Thus, a significant upward trend in evaporation is responsible for the decline in the volumes of water stored within the dam. The correlation analysis expresses that the losses in capacity of the Foum El Gherza dam have a strong impact with leakage and with liquid inflows.

Observed changes in precipitation during recent warming: The Czech Republic, 1961–2019

AbstractThis paper presents a comprehensive spatiotemporal analysis of precipitation patterns over the territory of the Czech Republic for the 1961–2019 period. Monthly, seasonal and annual series of precipitation totals and numbers of precipitation days were calculated for four altitudinal groups and the entire Czech Republic, based upon the daily precipitation totals recorded by 531 rain‐gauge stations run by the Czech Hydrometeorological Institute. Analysis of series of monthly, seasonal and annual precipitation totals revealed relatively stable fluctuations, while linear trends remained largely insignificant. However, wavelet analysis indicated significant interannual variability on a timescale of 4–8‐years in seasonal and annual series. The minimum in annual variation tended to appear in February (also in January and, at higher altitudes in particular, in April) with the maximum favouring July (but also June and August). The relative proportions of annual totals taken up by winter precipitation increased with altitude, while the proportions for summer precipitation decreased with altitude. Linear trends in the numbers of precipitation days exhibited the most pronounced decreases from April to June, reflected in negative precipitation trends in April–June and positive in July–September. The results obtained are also presented in the broader (central) European context.

How climate change is affecting the transitional natural zones of the Northern and Arctic regions of Russia

Continued global warming and the increase in climate extremes have mostly been identified in Northern and Arctic areas of Russia. Investigation of natural and climatic conditions in these regions was conducted using the method of zoning that is based on the environmental conditions of human life. This method estimates the relatively slowly changing landscape component and the rapidly changing climate component of the discomfort. Transitional natural zones represent an open system for the impact of climatic changes. A positive trend in the number of active temperatures and a negative precipitation trend was observed in these regions. At present, the climate conditions of some areas in the tundra, forest-tundra, and northern taiga correspond to the more southerly landscape zones. This situation is conducive to changes in the landscape vegetation and could lead to a shift in the transitional landscape zone borders towards higher latitudes. The relevancy of the study results is that they help to establish the potential consequences of climate change for landscape structures, as well as for the environment and the population of the Northern and Arctic areas. They can be used for developing the regulatory documents that govern the population's life in the Northern and Arctic areas.

Analysis of Surface Water Areal changes using Remote Sensing Data

Inland water bodies are crucial for supporting human life in various parts of the world. Therefore, it is essential to accurately monitor its spatiotemporal variations for better water management. The main objective of this study is to investigate the application of remote sensing data for quantifying the surface area changes and the impact of climatological variabilities over Lakes Mead and Chapala. Historical time series of monthly surface area dynamics were developed using Landsat 1-8 scenes and the climate variability was analysed using evaporation rate and precipitation. Results show that estimated surface water changes from satellite data agree well with independent data. A significant decline in surface area of about 40% since 2000 was found over the Lake Mead region. The relationship between surface area, precipitation and evaporation indicate that climatological factors have contributed to the lake surface area reduction. Lake Chapala’s surface area, on the other hand, has not fallen significantly despite negative trends in precipitation. It was found that human interactions with the lake are likely the main cause of surface area variations. The information about water surface area variation in this study is valuable for monitoring and characterising the predictability of water availability of the regions.

Contribution of precipitation events with different consecutive days to summer rainfall change over China

The climatological features, regional trends, and interdecadal changes of summer precipitation over China are investigated in this study from the perspective of four types of precipitation events with different consecutive days. The precipitation events are classified based on the consecutive days of precipitation into 1-to-3-, 4-to-7-, 8-to-14-, and over-14-day events. The contribution of 1-to-3-day events to climatological precipitation is larger than the other events over central Asia. Longer duration events contributed more than the shorter duration events to precipitation in tropical regions. The positive precipitation trend in northwestern and southern China is mainly due to 4-to-7-day and 8-to-14-day events, respectively; and the negative precipitation trend in North China is largely related to 4-to-7-day events. In general, the frequency change of precipitation events is a major reason for the precipitation change of these events in the concerned regions. The precipitation decrease in northern China around the mid-1960s is attributed to the reduction in 4-to-7-day events. The precipitation increase in northeastern and central China in the late 1970s is due to a combination of increases in 4-to-7-day and 8-to-14-day events. The precipitation increase in southern China around 1993 is mainly contributed by over-14-day events. The precipitation decrease in the mid-latitude Asia is due to the decrease in 4-to-7-day events. Most of the interdecadal precipitation changes are related to decrease or increase in the activity of anomalous cyclones. Results suggest that the frequency of occurrence of cyclonic perturbations is a major factor for interdecadal changes in summer precipitation over China.

Patterns of trends in niveograph characteristics across the western United States from snow telemetry data

The snowpack is changing across the globe, as the climate warms and changes. We used daily snow water equivalent (SWE) niveograph (time series of SWE) data from 458 snow telemetry (SNOTEL) stations for the period 1982 through 2012. Nineteen indices based on amount, timing, time length, and rates were used to describe the annual temporal evolution in SWE accumulation and ablation. The trends in these annual indices were computed over the time period for each station using the Theil-Sen slope. These trends were then clustered into four groups to determine the spatial pattern of SWE trends. Temperature and precipitation data were extracted from the PRISM data set, due to the shorter time period of temperature measurement at the SNOTEL stations. Results show that SNOTEL stations can be clustered in four clusters according to the observed trends in snow indices. Cluster 1 stations are mostly located in the Eastern- and South-eastern most parts of the study area and they exhibit a generalized decrease in the indices related with peak SWE and snow accumulation. Those stations recorded a negative trend in precipitation and an increase in temperature. Cluster 4 that is mostly restricted to the North and North-west of the study area shows an almost opposite pattern to cluster 1, due to months with positive trends and a more moderate increase of temperature. Stations grouped in clusters 2 and 3 appear mixed with clusters 1 and 4, in general they show very little trends in the snow indices.

Hydrometeorological changes in the North-East of Russia

The paper presents a comprehensive analysis of hydrometeorological changes at the river basins of the North-East of Russia for the period 1966-2015. Data from 61 meteorological stations showed an increase in the air temperature by an average of 2.3 °C and multidirectional changes in annual precipitation. Most stations are characterized by a significant negative trend of precipitation in winter and a positive annual trend of mixed and liquid precipitation with an increase in their share in autumn months. The presence of statistically significant positive streamflow trends in the autumn-winter period was established for 51 hydrological gauges. We hypothesize that the increase in the low flow is mainly due to the transition of precipitation type from solid to liquid and corresponding increase of runoff in September, continuing in the following months.