Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-05-15 Cooperative journals: 《干旱区科学》
Abstract： The desert-oasis transition zone (DOTZ) serves as a buffer area between the desert and oasis. Understanding its wind field characteristics is of great significance for the prevention and control of aeolian disasters in the oasis. In this study, we used meteorological data during 2013–2019 from the portable meteorological stations at five sites (site A on the edge of the oasis, sites B, C, and D in the DOTZ, and site O in the desert) in Dunhuang, China to analyze the near-surface wind field characteristics and their causes, as well as to reveal the key role of the DOTZ in oasis protection. The results showed that the mean wind speed, frequency of sand-driving wind, and directional variability of wind decreased from west to east within the DOTZ, and wind speed was significantly affected by air temperature. The terrain influenced the prevailing winds in the region, mainly from northeast and southwest. Only some areas adjacent to the oasis were controlled by southeasterly wind. This indicated that the near-surface wind field characteristics of the DOTZ were caused by the combined effects of local terrain and surface hydrothermal difference. At site D, the annual drift potential (DP) was 24.95 vector units (VU), indicating a low wind energy environment, and the resultant drift direction (RDD) showed obvious seasonal differences. Additionally, the DOTZ played an important buffering role between the desert and oasis. Compared with the desert, the mean wind speed in the oasis decreased by 64.98%, and the prevailing wind direction was more concentrated. The results of this study will be useful in interpreting the aeolian activity of the DOTZ in Dunhuang.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-04-15 Cooperative journals: 《干旱区科学》
Abstract： Rain-on-snow (ROS) events involve rainfall on snow surfaces, and the occurrence of ROS events can exacerbate water scarcity and ecosystem vulnerability in the arid region of Northwest China (ARNC). In this study, using daily snow depth data and daily meteorological data from 68 meteorological stations provided by the China Meteorological Administration National Meteorological Information Centre, we investigated the spatiotemporal variability of ROS events in the ARNC from 1978 to 2015 and examined the factors affecting these events and possible changes of future ROS events in the ARNC. The results showed that ROS events in the ARNC mainly occurred from October to May of the following year and were largely distributed in the Qilian Mountains, Tianshan Mountains, Ili River Valley, Tacheng Prefecture, and Altay Prefecture, with the Ili River Valley, Tacheng City, and Altay Mountains exhibiting the most occurrences. Based on the intensity of ROS events, the areas with the highest risk of flooding resulting from ROS events in the ARNC were the Tianshan Mountains, Ili River Valley, Tacheng City, and Altay Mountains. The number and intensity of ROS events in the ARNC largely increased from 1978 to 2015, mainly influenced by air temperature and the number of rainfall days. However, due to the snowpack abundance in areas experiencing frequent ROS events in the ARNC, snowpack changes exerted slight impact on ROS events, which is a temporary phenomenon. Furthermore, elevation imposed lesser impact on ROS events in the ARNC than other factors. In the ARNC, the start time of rainfall and the end time of snowpack gradually advanced from the spring of the current year to the winter of the previous year, while the end time of rainfall and the start time of snowpack gradually delayed from autumn to winter. This may lead to more ROS events in winter in the future. These results could provide a sound basis for managing water resources and mitigating related disasters caused by ROS events in the ARNC.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-03-13 Cooperative journals: 《干旱区科学》
Abstract： Land surface temperature (LST) directly affects the energy balance of terrestrial surface systems and impacts regional resources, ecosystem evolution, and ecosystem structures. Xinjiang Uygur Autonomous Region is located at the arid Northwest China and is extremely sensitive to climate change. There is an urgent need to understand the distribution patterns of LST in this area and quantitatively measure the nature and intensity of the impacts of the major driving factors from a spatial perspective, as well as elucidate the formation mechanisms. In this study, we used the MOD11C3 LST product developed on the basis of Moderate Resolution Imaging Spectroradiometer (MODIS) to conduct regression analysis and determine the spatiotemporal variation and differentiation pattern of LST in Xinjiang from 2000 to 2020. We analyzed the driving mechanisms of spatial heterogeneity of LST in Xinjiang and the six geomorphic zones (the Altay Mountains, Junggar Basin, Tianshan Mountains, Tarim Basin, Turpan-Hami (Tuha) Basin, and Pakakuna Mountain Group) using geographical detector (Geodetector) and geographically weighted regression (GWR) models. The warming rate of LST in Xinjiang during the study period was 0.24°C/10a, and the spatial distribution pattern of LST had obvious topographic imprints, with 87.20% of the warming zone located in the Gobi desert and areas with frequent human activities, and the cooling zone mainly located in the mountainous areas. The seasonal LST in Xinjiang was at a cooling rate of 0.09°C/10a in autumn, and showed a warming trend in other seasons. Digital elevation model (DEM), latitude, wind speed, precipitation, normalized difference vegetation index (NDVI), and sunshine duration in the single-factor and interactive detections were the key factors driving the LST changes. The direction and intensity of each major driving factor on the spatial variations of LST in the study area were heterogeneous. The negative feedback effect of DEM on the spatial differentiation of LST was the strongest. Lower latitudes, lower vegetation coverage, lower levels of precipitation, and longer sunshine duration increased LST. Unused land was the main heat source landscape, water body was the most important heat sink landscape, grassland and forest land were the land use and land cover (LULC) types with the most prominent heat sink effect, and there were significant differences in different geomorphic zones due to the influences of their vegetation types, climatic conditions, soil types, and human activities. The findings will help to facilitate sustainable climate change management, analyze local climate and environmental patterns, and improve land management strategies in Xinjiang and other arid areas.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-03-13 Cooperative journals: 《干旱区科学》
Abstract： The isotope composition in precipitation has been widely considered as a tracer of monsoon activity. Compared with the coastal region, the monsoon margin usually has limited precipitation with large fluctuation and is usually sensitive to climate change. The water resource management in the monsoon margin should be better planned by understanding the composition of precipitation isotope and its influencing factors. In this study, the precipitation samples were collected at five sampling sites (Baiyin City, Kongtong District, Maqu County, Wudu District, and Yinchuan City) of the monsoon margin in the northwest of China in 2022 to analyze the characteristics of stable hydrogen (δD) and oxygen (δ18O) isotopes. We analyzed the impact of meteorological factors (temperature, precipitation, and relative humidity) on the composition of precipitation isotope at daily level by regression analysis, utilized the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT)-based backward trajectory model to simulate the air mass trajectory of precipitation events, and adopted the potential source contribution function (PSCF) and concentration weighted trajectory (CWT) to analyze the water vapor sources. The results showed that compared with the global meteoric water line (GMWL), the slope of the local meteoric water line (LMWL; δD=7.34δ18O–1.16) was lower, indicating the existence of strong regional evaporation in the study area. Temperature significantly contributed to δ18O value, while relative humidity had a significant negative effect on δ18O value. Through the backward trajectory analysis, we found eight primary locations that were responsible for the water vapor sources of precipitation in the study area, of which moisture from the Indian Ocean to South China Sea (ITSC) and the western continental (CW) had the greatest influence on precipitation in the study area. The hydrogen and oxygen isotopes in precipitation are significantly influenced by the sources and transportation paths of air mass. In addition, the results of PSCF and CWT analysis showed that the water vapor source areas were primarily distributed in the south and northwest direction of the study area.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-03-13 Cooperative journals: 《干旱区科学》
Abstract： Xinjiang Uygur Autonomous Region is a typical inland arid area in China with a sparse and uneven distribution of meteorological stations, limited access to precipitation data, and significant water scarcity. Evaluating and integrating precipitation datasets from different sources to accurately characterize precipitation patterns has become a challenge to provide more accurate and alternative precipitation information for the region, which can even improve the performance of hydrological modelling. This study evaluated the applicability of widely used five satellite-based precipitation products (Climate Hazards Group InfraRed Precipitation with Station (CHIRPS), China Meteorological Forcing Dataset (CMFD), Climate Prediction Center morphing method (CMORPH), Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR), and Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA)) and a reanalysis precipitation dataset (ECMWF Reanalysis v5-Land Dataset (ERA5-Land)) in Xinjiang using ground-based observational precipitation data from a limited number of meteorological stations. Based on this assessment, we proposed a framework that integrated different precipitation datasets with varying spatial resolutions using a dynamic Bayesian model averaging (DBMA) approach, the expectation-maximization method, and the ordinary Kriging interpolation method. The daily precipitation data merged using the DBMA approach exhibited distinct spatiotemporal variability, with an outstanding performance, as indicated by low root mean square error (RMSE=1.40 mm/d) and high Person's correlation coefficient (CC=0.67). Compared with the traditional simple model averaging (SMA) and individual product data, although the DBMA-fused precipitation data were slightly lower than the best precipitation product (CMFD), the overall performance of DBMA was more robust. The error analysis between DBMA-fused precipitation dataset and the more advanced Integrated Multi-satellite Retrievals for Global Precipitation Measurement Final (IMERG-F) precipitation product, as well as hydrological simulations in the Ebinur Lake Basin, further demonstrated the superior performance of DBMA-fused precipitation dataset in the entire Xinjiang region. The proposed framework for solving the fusion problem of multi-source precipitation data with different spatial resolutions is feasible for application in inland arid areas, and aids in obtaining more accurate regional hydrological information and improving regional water resources management capabilities and meteorological research in these regions.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-02-21 Cooperative journals: 《干旱区科学》
Abstract： Climate warming profoundly affects hydrological changes, agricultural production, and human society. Arid and semi-arid areas of China are currently displaying a marked trend of warming and wetting. The Chinese Tianshan Mountains (CTM) have a high climate sensitivity, rendering the region particularly vulnerable to the effects of climate warming. In this study, we used monthly average temperature and monthly precipitation data from the CN05.1 gridded dataset (1961–2014) and 24 global climate models (GCMs) of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to assess the applicability of the CMIP6 GCMs in the CTM at the regional scale. Based on this, we conducted a systematic review of the interannual trends, dry–wet transitions (based on the standardized precipitation index (SPI)), and spatial distribution patterns of climate change in the CTM during 1961–2014. We further projected future temperature and precipitation changes over three terms (near-term (2021–2040), mid-term (2041–2060), and long-term (2081–2100)) relative to the historical period (1961–2014) under four shared socio-economic pathway (SSP) scenarios (i.e., SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). It was found that the CTM had experienced significant warming and wetting from 1961 to 2014, and will also experience warming in the future (2021–2100). Substantial warming in 1997 was captured by both the CN05.1 derived from interpolating meteorological station data and the multi-model ensemble (MME) from the CMIP6 GCMs. The MME simulation results indicated an apparent wetting in 2008, which occurred later than the wetting observed from the CN05.1 in 1989. The GCMs generally underestimated spring temperature and overestimated both winter temperature and spring precipitation in the CTM. Warming and wetting are more rapid in the northern part of the CTM. By the end of the 21st century, all the four SSP scenarios project warmer and wetter conditions in the CTM with multiple dry–wet transitions. However, the rise in precipitation fails to counterbalance the drought induced by escalating temperature in the future, so the nature of the drought in the CTM will not change at all. Additionally, the projected summer precipitation shows negative correlation with the radiative forcing. This study holds practical implications for the awareness of climate change and subsequent research in the CTM.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2024-02-07 Cooperative journals: 《干旱区科学》
Abstract： Climate warming profoundly affects hydrological changes, agricultural production, and human society. Arid and semi-arid areas of China are currently displaying a marked trend of warming and wetting. The Chinese Tianshan Mountains (CTM) have a high climate sensitivity, rendering the region particularly vulnerable to the effects of climate warming. In this study, we used monthly average temperature and monthly precipitation data from the CN05.1 gridded dataset (1961–2014) and 24 global climate models (GCMs) of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to assess the applicability of the CMIP6 GCMs in the CTM at the regional scale. Based on this, we conducted a systematic review of the interannual trends, dry–wet transitions (based on the standardized precipitation index (SPI)), and spatial distribution patterns of climate change in the CTM during 1961–2014. We further projected future temperature and precipitation changes over three terms (near-term (2021–2040), mid-term (2041–2060), and long-term (2081–2100)) relative to the historical period (1961–2014) under four shared socio-economic pathway (SSP) scenarios (i.e., SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5). It was found that the CTM had experienced significant warming and wetting from 1961 to 2014, and will also experience warming in the future (2021–2100). Substantial warming in 1997 was captured by both the CN05.1 derived from interpolating meteorological station data and the multi-model ensemble (MME) from the CMIP6 GCMs. The MME simulation results indicated an apparent wetting in 2008, which occurred later than the wetting observed from the CN05.1 in 1989. The GCMs generally underestimated spring temperature and overestimated both winter temperature and spring precipitation in the CTM. Warming and wetting are more rapid in the northern part of the CTM. By the end of the 21st century, all the four SSP scenarios project warmer and wetter conditions in the CTM with multiple dry–wet transitions. However, the rise in precipitation fails to counterbalance the drought induced by escalating temperature in the future, so the nature of the drought in the CTM will not change at all. Additionally, the projected summer precipitation shows negative correlation with the radiative forcing. This study holds practical implications for the awareness of climate change and subsequent research in the CTM.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： Based on daily temperature observation data and reanalysis data of the geopotential height, sea levelpressure, and wind field from 1961 to 2020, the characteristics of spatial and temporal change of cold waves,strong cold waves, and exceptionally strong cold waves lasting 24 h, 48 h, and 72 h were studied in Ningxia overthe past 60 years. The causes of atmospheric circulation anomalies of cold waves were also revealed. The resultsshow the following: (1) In the past 60 years, cold waves of different intensities and different durations in Ningxiaconsistently showed the distribution characteristics of“shifting eastwards and northwards.”(2) The cumulativefrequencies of cold waves, strong cold waves, and exceptionally strong cold waves in the region accounted for71.7%, 22.6%, and 5.7% of the total annual cold wave frequencies, respectively, among which cold wavesdominated by process lasting 24 h and 48 h. The proportions of various durations for strong cold waves andexceptionally strong cold waves were equivalent. They mainly occured in October to April, during which theaccumulated cold waves, strong cold waves, and exceptionally strong cold waves in the region accounted for99%, 98%, and 95% of those throughout the year, and there was a decreasing trend from January to April andincreasing trend from October to December. (3) In the past 60 years, the cold waves, strong cold waves, andexceptionally strong cold waves have been decreasing at a rate of 4.5, 2.8, and 0.18 per station every 10 years,respectively. Among them, the frequencies of waves of 24 h and 48 h as short durations were decreasing, but thatof waves of 72 h as a long duration was decreasing. All types of cold waves decreased from the 1960s to the1990s, reaching a minimum in the 1990s and increasing since the 2000s, with a sudden change around 1990. (4)Under the influence of global warming, the atmospheric circulation showed completely the opposite distributioncharacteristics between before and after the sudden change of cold waves in Ningxia. The key systemsinfluencing cold waves in Ningxia are consistent. When the blocking high pressure in the Ural Mountains wasstronger, the East Asian trough was deeper, the west Pacific subtropical high was weaker, the western side ofLake Baikal was dominated by cyclonic circulation, and cold high pressure at the ground was active, this wasconducive to the southward movement of cold air in middle and high latitudes, and more cold waves in Ningxia.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-12-16 Cooperative journals: 《干旱区研究》
Abstract： This study used the Sen+M-K trend analysis, the gravity center movement model, the standardizedregression coefficient, and the spatial clustering methods to reveal the spatial characteristics of the variation,trends, and movement of dust days of various types and the contribution rate of their influencing factors in theTarim Basin based on the annual data of 32 meteorological stations between 1964 and 2022. The resultsindicated: (1) Floating dust, followed by blowing sand and sandstorms, dominate the Tarim Basin, showing aspatial distribution pattern of more in the south and less in the north, and the dust days of various types showsignificantly decreasing trends. (2) The gravity centers of dust days of various types in the Tarim Basin tended tomove southeast, and the gravity center of sandstorm days moved the most. (3) Warmer temperatures, lower windspeeds, and fewer gale days were the main factors in the decreased dust days in the Tarim Basin, whereasprecipitation had the least influence. (4) The high contribution rates of precipitation to dust days are clustered inthe western part of the Tarim Basin, mean temperature and mean maximum temperature in the southern andwestern parts, respectively, and gale days and mean wind speed in the northwestern and southeastern parts,respectively. This study’s results can provide a scientific basis for developing regionally applicable windbreakingand sand-fixing measures in the Tarim Basin.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： Analyzing the response of tree radial growth to climate change is crucial for accurately predicting thedynamic changes in forests in the future. The temperate coniferous forest, dominated by Picea schrenkiana, iswidely distributed in the mid-mountain zone on the northern slope of the Tianshan Mountains. In this study, coresamples of high-altitude Picea schrenkiana were collected, and the response characteristics of Picea schrenkianaradial growth to climatic factors and drought events were explored using tree-ring analysis. The results showedthe following: (1) From 1960 to 2020, the tree- ring width index of Picea schrenkiana showed a significantupward trend without any growth recession, indicating favorable growth conditions in recent years. (2) The treeringwidth of Picea schrenkiana was mainly positively correlated with temperature from June to August,precipitation in April, and scPDSI in all months except July. Sliding correlation analysis showed an unstablerelationship between tree-ring width and climatic factors. After 1991, the positive response of spruce to climatic factorswas further strengthened. (3) The percentage of radial growth change in Picea schrenkiana was less than −25% from1879 to 1880, indicating a growth decline from 1879 to 1885. An increase in drought frequency and intensityresulted in a decrease in the resistance and resilience of Picea schrenkiana to drought events. When Piceaschrenkiana was in a relatively sufficient water environment for a long time and suffered from sudden droughtevents, it exhibited a significant decline in resistance and was prone to growth decline. In summary, under theinfluence of climate change, warming is still expected to promote the radial growth of high- altitude Piceaschrenkiana in the region in the near future. However, the increase in the frequency and intensity of droughtevents during the warming process will further reduce the resistance and resilience of Picea schrenkiana, posingan increased risk of growth decline. In the near future, Picea schrenkiana will face the challenge of balancinggrowth promotion due to warming and growth inhibition due to drought. Further observation and research arerequired to understand the ultimate impact. In the future, various methods should be implemented to closelymonitor the growth dynamics of Picea schrenkiana.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-26 Cooperative journals: 《干旱区研究》
Abstract： The microphysical parameters, average characteristics of raindrop spectra, and gamma distributionparameters of three types of rainfall (stratiform, cumulonimbus, and stratocumulus) were analyzed using raindropspectrum data from different stations of 58 rainfall processes in the Liupan Mountains from 2020 to 2021. Theresults are as follows: (1) The mean values for all microphysical parameters at each station were higher forcumulonimbus rainfall compared to stratocumulus and stratiform rainfall. In stratiform and stratocumulusrainfall, the mean diameter (Dave) and mode diameter (Dmode) were smaller at the top and bottom of the mountainand greater on the mountainside. Conversely, the maximum diameter (Dmax), mass- weighted mean diameter(Dmode), rain rate (R), radar reflectivity (Z), and liquid water content (Q) increased with elevation on the east andwest slopes. (2) The contributions of small raindrops to rain rate (R) and number concentration (N) were higher instratiform and stratocumulus rainfall than in cumulonimbus rainfall. However, the contributions of small andmedium-sized raindrops to N and R, respectively, were higher in cumulonimbus rainfall than in stratiform andstratocumulus rainfall. (3) The N0, μ, and λ parameters of gamma distribution decreased with an increase inaltitude. The slope of the μ-λ fitting curve was closely related to the type of rainfall. (4) Compared with the footof the mountain sites, the peak site exhibited a decrease in raindrop number concentration (Nw) and an increase inmean scale (Dm). (5) The characteristic diameter and microphysical parameters varied under different circulationsituations.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： The linear tendency, cumulative anomaly, and Mann-Kendall test were used to analyze the temporaland spatial variation of temperature in Dunhuang, Guazhou, and Yumen stations in the Shule River Basin from1951 to 2020. The results revealed that (1) all stations experienced a significant upward trend in averagetemperature, with tendency rates of 0.244 °C·(10a)−1 (P<0.05) for Dunhuang station, 0.209 °C·(10a)−1 (P<0.05)for Guazhou station, and 0.195 ° C · (10a) − 1 (P<0.05) for Yumen station. (2) Dunhuang and Yumen stationsexhibited a significant upward trend in average temperature across all seasons, except for a nonsignificant upwardtrend in summer. (3) the mutation years for average temperature at Dunhuang, Guazhou, and Yumen stations were1998, 1997, and 1995, respectively, with the first main cycles being 58 a, 30 a, and 13 a, respectively. (4) andannual and seasonal average temperatures gradually increased from east to west in the Shule River Basin, withdecreasing nonuniformity coefficients and concentration degrees also observed.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Based on the ECMWF fine grid numerical prediction product and the temperature observation data ofthe national assessment station, the weighted quasi- symmetric running training period method (WQSRTP) wasused to generate the maximum (low) objective product of the smart grid in Gansu Province. The results werecompared with the smart grid guidance forecast product (SCMOC) of China Meteorological Administration andthe urban grid forecast product (SPCC) of Gansu Province. The results show that the WQSRTP correction methodcan significantly improve the ability to predict the 24 h maximum (low) temperature of the ECMWF fine gridnumerical model, and the predictive accuracy of the 24 h maximum and minimum temperatures increased by32.16% and 15.48% , respectively. Compared with SCMOC, SPCC, and ECMWF, the modified WQSRTPproducts are positive correction techniques, and the modified ability of maximum temperature is better than thatof minimum temperature. According to the spatial error test, the WQSRTP correction method can effectivelyimprove the accuracy of maximum (low) temperature forecast in the Qilian Mountains and the SouthwestMountains, and significantly reduce the mean absolute error. Moreover, the effect of correction for predicting themaximum temperature is better than that of minimum temperature.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Using MOD10A2 snow product data from 2001 to 2020, along with digital elevation andmeteorological data, the spatiotemporal variation of snow cover in the Altai Mountains, Xinjiang, and theinfluence of topographic and meteorological factors over this period were analyzed. The results indicated thefollowing. (1) Snow cover percentage (SCP) in the Altai Mountains of Xinjiang exhibited a decreasing overalltrend from 2001 to 2020, with the lowest and highest values observed in 2007 and 2010, respectively, and avariation rate of − 5.69%·(10a) − 1. Troughs were observed throughout the year, with maximum and minimumtroughs in January and July, respectively. Seasonally, SCP increased in fall and decreased in the other threeseasons. The uneven distribution of climate conditions, including temperature and precipitation, causedfluctuations in the timing of maximum annual snow cover occurrence. The Altai annual SCP reached its peakbetween 96.45% and 99.92%, primarily observed in January and December. The lowest coverage range was0.84%-2.27%, which occurred in July and August. (2) SCP showed a positive correlation with altitude, withlower SCP values below 500 m (average of 8.11%) and higher values above 2000 m (average of 99.08% in anarea with stable snow cover all year round). SCP varied depending on the slope, with the northwest slopeexhibiting the highest values (28.45%) and the south slope showing the lowest values (18.36%). (3) Land surfacetemperature exhibited higher and lower distributions in the northeast and southwest, respectively, and wassignificantly positively correlated with altitude. Moreover, 67.65% of the Altai Mountain region showed adownward trend in snow cover frequency (SCF) from 2001 to 2020. High mountain areas experienced increasingSCF, whereas plain and river areas exhibited decreasing SCF. (4) Temperature was the main factor influencingsnow cover change, being negatively correlated with SCF over 9.08 × 103 km2 (80.52% of the total AltaiMountain area). Therefore, as altitude increases, the impact of temperature on snow cover gradually diminishes.Annual average precipitation in Altai decreased gradually from northwest to southeast, and precipitation waspositively correlated with 87.14% of regional SCF, with a weakened effect on SCF changes observed in highaltitudemountain areas and a more significant correlation observed in low-altitude areas.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： The prediction performance of four seasonal prediction model systems (BCC_CSM 1.1,ECMWF_System 5, CFSv 2, and TCC_MRI-CGCM 3) was evaluated from a deterministic perspective. Focusingon the spatial distribution and temporal variation of precipitation climatology in early winter, BCC_CSM 1.1exhibited the best prediction performance among the models. Additionally, TCC_MRI-CGCM 3 performed wellin capturing the interannual variability of precipitation, followed by BCC_CSM 1.1. All models effectivelysimulated regional-uniform precipitation, with BCC_CSM 1.1 exhibiting the highest time correlation coefficientand TCC_MRI- CGCM 3 showing the highest pattern correlation coefficient. Although all models couldreproduce the north-south reverse mode, BCC_CSM 1.1 outperformed the other models in terms of reproducingthe spatial pattern and interannual variation, given the model’s strong prediction capability for the Eurasian (EU)teleconnection pattern and western Pacific subtropical high, as well as accurate simulations of the physicalprocesses of El Niño- Southern Oscillation (ENSO) and Indian Ocean dipole (IOD) that impact early winterTibetan Plateau precipitation.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： The Sahara region of northern Africa is seriously affected by drought and desertification, and eoliandust activity disasters are considered severe. The arid and semi-arid regions of Egypt in northern Africa were thefocus of this study. Based on daily observation data from meteorological stations between 1990 and 2020, and thedata obtained from satellite remote sensing products, the spatiotemporal variability characteristics of eolian dustactivity disasters in Egypt and their possible associations were assessed. The main influencing factors of eoliandust activity disasters were further discussed. The frequency of eolian dust activities in Egypt varied from 20 to65 d·a− 1 over the past 30 years, showing an overall declining trend with fluctuations. The annual average totalsuspended particulate (TSP) concentration in Egypt fluctuates was 400-1200 μg·mg− 3 and showed an overalldecreasing trend over the past 30 years. The highest TSP concentration occurred during spring in Egypt andreached over 2300 μg·m− 3. Eolian dust activity in Egypt has a high intensity level when compared to other aridand semi- arid regions of the world; Egypt has the highest frequency of blowing dust, followed by dust insuspension, dust storm, and severe dust storm. The blowing dust that occurs in spring and summer accounts formore than 60% of the total eolian dust weather throughout the year. Ambient TSP concentrations in Egypt arehighly correlated with the frequency of eolian dust activity due to wind erosion; There has been a deceasing trendin surface wind speed over the past 30 years, and wind erosion is an important factor affecting air quality in theoasis areas. The frequency of eolian dust activity is significantly negatively correlated with the Atlanticmultidecadal oscillation with a correlation coefficient of − 0.67. This work provides theoretical basis and datasupport for a comprehensive understanding of the spatial-temporal characteristics of eolian dust weather in Egypt,North Africa, and the prevention of dust storm disasters.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： This study has aimed to evaluate the characteristics of the atmospheric environmental capacity and itsinfluencing factors in Ningxia. The temporal and spatial distribution of the A value of the atmosphericenvironmental capacity and its main meteorological influencing factors were analyzed using daily fixed timehistorical observation data from meteorological stations between 1961 and 2018, based on the box modelprinciple. The atmospheric environmental capacity in 2018 was also evaluated and zoned. The results showed thatthe A value of the atmospheric environmental capacity showed a decreasing trend in all seasons, with a rate of-0.47 ×104~-0.24 ×104 km2 ·(10a) − 1. The annual average A value was largest in the summer, followed by thespring, and then autumn and winter. The monthly A value showed a single peak pattern, with a maximum inAugust and minimum in December. It was generally high in the south and low in the north in space, andinfluenced by the topography of Helan Mountain and Liupan Mountain, regional precipitation, and other climaticfactors. The low value center for A was located in Yinchuan and Shizuishan City, while the high value center waslocated in the south of Guyuan City. Wind speed and mixed layer height changes had a significant influence onthe interdecadal evolution trend of the atmospheric environmental capacity of A in the Ningxia Hui AutonomousRegion. There were obvious seasonal and regional differences on the impacts of precipitation and wind speed.For example, wind speed had a greater contribution to the A value in spring in the north, and precipitation had agreater contribution to the A value in summer and autumn in the south. This was affected by high energyconsuming industries such as metallurgy, thermal power, the chemical industry, and construction and vehicleemissions. Pingluo County and Litong District were the critical overload and overload areas for the SO2 and NOxatmospheric environments, and the counties south of Litong District were high bearing areas in Ningxia.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Using the air pollutant mass concentration data in Xinjiang from March 2021 to February 2022, theevolution characteristics of PM2.5 concentration and its potential contribution source area were analyzed. Theresults showed that: (1) The concentration of PM2.5 in Xinjiang was significantly high, especially in winter, theaverage was as high as 86.16 μg·m-3, which had certain potential risks to human health. Influenced by the nearsurfaceair stability, the PM2.5 concentration was higher at nighttime and lower in the daytime, but supplementedby (similar) valley winds, the PM2.5 concentration exhibited a significant double-peak pattern in the Hami Basinand the Tarim Basin. (2) The PM2.5 in the economic belt of the northern slope of the Tianshan Mountains wasmainly dominated by the emission from the surrounding oil and gas fields and the dust from strong winds duringthe transportation process, while the source of PM2.5 in other areas, where human activities were relatively weak,was mainly controlled by the dust from strong winds, supplemented by the combustion of oil and natural gas. (3)The overall low concentration of PM2.5 in each path in the source region of the Irtysh River indicates that theimpact of pollutants on environmental quality could be ignored. The high concentration of PM2.5 in the NB areawas mainly affected by the local atmospheric circulation, but the airflow passing through the oil and gas industryarea was a key factor leading to the formation of haze and floating dust weather. Although there are differences inthe material supply paths between the Hami Basin and the Tarim Basin, their PM2.5 potential contribution sourceareas were all mainly distributed in the Kongqi River Basin and Lop Nur on the eastern edge of the TaklimakanDesert. (4) Exogenous airflow evolved into convergent/divergent airflow due to the topography of the basin,supplemented by (quasi) valley winds to promote the mixing of pollutants, which could be the key factor for thesimilar evolution trend of PM2.5 in the economic belt of the northern slope of the Tianshan Mountains and TarimBasin.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： The temporal variation, spatial distribution, and temporal and spatial evolution characteristics of thetotal radiation in Northwest China were studied using meteorological observation data from 169 nationalmeteorological stations in Northwest China, over the past 60 years. The Qaidam Basin in the Northwest ofQinghai and the west of Gansu were the most abundant areas for solar energy resources, the smaller areas in thesouth of Shaanxi and the southeast of Gansu were found to be resource rich areas, and the other large areas areresource rich areas. From 1961 to 2020, the total radiation showed an upward trend in Southwest Xinjiang, theborder area between Gansu and Xinjiang, and smaller areas in northern Gansu and northern Shaanxi, while thetotal radiation showed a downward trend in most regions of Northwest China. The eigenvector field of EOF mode1 shows that the total radiation oscillation intensifies from west to east, and the high load area for eachcomponent is mainly concentrated in the middle and east, which is the region where the total radiation is prone tobe abnormal and the oscillation is strong and sensitive. The eigenvector field of the second EOF mode presents adipole type from west to east. Qinghai and most of the Gansu are positive regions, which are also the regions withthe strongest total radiation and abnormal oscillation. According to the different modal spatial differentiationstructure types for the REOF eigenvectors, the study area can be divided into three sub regions, namely:“Easternnorthwest anomaly type”which is affected by the East Asian monsoon;“Central northwest anomaly type”whichis the marginal region and mainly affected by the East Asian monsoon; and“Western Northwest anomaly type”which is mainly affected by the westerlies. The mutation points for total radiation reduction in the threesubregions occurred in 1973, 2017, and 2008 respectively.
Subjects: Geosciences >> Atmospheric Sciences submitted time 2023-08-25 Cooperative journals: 《干旱区研究》
Abstract： Globally, China is one of the country’s most frequently and severely affected by drought. Thesefrequent drought events have subsequently caused serious economic, social development, and ecologicalenvironment losses. Drought simultaneously leads to alterations in both space and time, and this paper aims toidentify drought events and quantify their spatial and temporal dynamic evolution using a three- dimensionalclustering algorithm for mainland China, from 1981-2020. The three- dimensional clustering algorithm can beused to effectively identify drought events and describe their dynamic processes. From 1981-2020 there were102 drought events lasting 2 months or more in mainland China. Spatially, the trajectory of drought events wasfound to show a tendency to develop from east to west. Temporally, there are high time overlaps betweendifferent drought events. In addition, drought events with wide coverage and high severity were concentrated inthe period from 2005-2010. The findings of this paper will help to elucidate the spatial and temporal evolutionpatterns of drought events and provide scientific references for drought monitoring and drought risk managementin mainland China.
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