Multiscale evolution of surface air temperature in the arid region of Northwest China and its linkages to ocean oscillations   总被引：1，自引：0，他引：1  

Chen  Zhongsheng  Chen  Yaning  Bai  Ling  Xu  Jianhua 《Theoretical and Applied Climatology》2017,130(3-4):945-958

Reference crop evapotranspiration (ETo) is one of the most important links in hydrologic circulation and greatly affects regional agricultural production and water resource management. Its variation has drawn more and more attention in the context of global warming. We used the Penman-Monteith method of the Food and Agriculture Organization, based on meteorological factors such as air temperature, sunshine duration, wind speed, and relative humidity to calculate the ETo over 46 meteorological stations located in the Yangtze River Delta, eastern China, from 1957 to 2014. The spatial distributions and temporal trends in ETo were analyzed based on the modified Mann-Kendall trend test and linear regression method, while ArcGIS software was employed to produce the distribution maps. The multiple stepwise regression method was applied in the analysis of the meteorological variable time series to identify the causes of any observed trends in ETo. The results indicated that annual ETo showed an obvious spatial pattern of higher values in the north than in the south. Annual increasing trends were found at 34 meteorological stations (73.91 % of the total), which were mainly located in the southeast. Among them, 12 (26.09 % of the total) stations showed significant trends. We saw a dominance of increasing trends in the monthly ETo except for January, February, and August. The high value zone of monthly ETo appeared in the northwest from February to June, mid-south area from July to August, and southeast coastal area from September to January. The research period was divided into two stages—stage I (1957–1989) and stage II (1990–2014)—to investigate the long-term temporal ETo variation. In stage I, almost 85 % of the total stations experienced decreasing trends, while more than half of the meteorological stations showed significant increasing trends in annual ETo during stage II except in February and September. Relative humidity, wind speed, and sunshine duration were identified as the most dominant meteorological variables influencing annual ETo changes. The results are expected to assist water resource managers and policy makers in making better planning decisions in the research region.  相似文献   

Understanding the spatial differences in terrestrial water storage variations in the Tibetan Plateau from 2002 to 2016   总被引：1，自引：0，他引：1  

Haijun Deng  Qun Liu  Yaning Chen 《Climatic change》2018,151(3-4):379-393

Climate change has been driving terrestrial water storage variations in the high mountains of Asia in the recent decades. This study is based on Gravity Recovery and Climate Experiment (GRACE) data to analyse spatial and temporal variations in terrestrial water storage (TWS) across the Tibetan Plateau (TP) from April 2002 to December 2016. Regional averaged TWS anomaly has increased by 0.20 mm/month (p?<?0.01) during the 2002–2012 period, but decreased by ??0.68 mm/month (p?<?0.01) since 2012. The seasonal variations in TWS anomalies also showed a decreasing trend from May 2012 to December 2016. TWS variations in the TP also showed significant spatial differences, which were decreasing in southern TP but increasing in the Inner TP. And a declining trend was clearly evident in the seasonal variability of TWS anomalies in the south TP (about ??30 to ??55 mm/a), but increasing in the inner TP (about 10–35 mm/a). Meanwhile, this study links temperature/precipitation changes, glacial retreat and lake area expansion to explain the spatial differences in TWS. Results indicated that precipitation increases and lake area expansion drove increasing TWS in the Inner TP during the 2002–2016 period, but temperature increases and glacial retreat drove decreasing TWS in southern TP.  相似文献   

NDVI-based vegetation responses to climate change in an arid area of China   总被引：2，自引：0，他引：2  

Yufeng Xu  Jing Yang  Yaning Chen 《Theoretical and Applied Climatology》2016,125(1-2):213-225

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Effect of sub-cloud evaporation on precipitation in the Tianshan Mountains (Central Asia) under the influence of global warming     

Haiyan Chen  Yaning Chen  Dalong Li  Weihong Li 《水文研究》2020,34(26):5557-5566

It is crucial for accurately describing the precipitation patterns and their underlying mechanisms to optimise the hydro-climatic model parameters and improve the accuracy of precipitation forecasting. Based on 212 precipitation samples collected during August 2015 to July 2016 in the mid-mountain region of the Manasi River Basin in the northern slope of the Tianshan Mountains, we estimated the effect of sub-cloud evaporation on precipitation, analysed the factors that influence the sub-cloud evaporation, and modelled the response of sub-cloud evaporation to global warming. The mean remaining raindrop mass fraction after evaporation (f ) in this region is 94.39%. The mean deviation between d-excess (Δd ) of ground precipitation and raindrops under cloud is −4.22‰. The intensity of sub-cloud evaporation is the highest in summer. There is a significant positive correlation between f and Δd (0.72‰/%). The relative humidity and diameter of raindrops were observed to have a direct influence on the intensity of sub-cloud evaporation. The temperature was observed to influence the intensity of sub-cloud evaporation indirectly by influencing the relative humidity and diameter of raindrops. Global warming will increase the intensity of sub-cloud evaporation in the Tianshan Mountains, especially for small precipitation events.  相似文献   

Spatial distribution and temporal trends of mean precipitation and extremes in the arid region,northwest of China,during 1960–2010     

Huaijun Wang  Yaning Chen  Zhongsheng Chen 《水文研究》2013,27(12):1807-1818

On the basis of daily precipitation records at 76 meteorological stations in the arid region, northwest of China, the spatial and temporal distribution of mean precipitation and extremes were analysed during 1960–2010. The Mann–Kendall trend test and linear least square method were utilized to detect monotonic trends and magnitudes in annual and seasonal mean precipitation and extremes. The results obtained indicate that both the mean precipitation and the extremes have increased except in consecutive dry days, which showed the opposite trend. The changes in amplitude of both mean precipitation and extremes show seasonal variability. On an annual basis, the number of rain days (R0.1) has significantly increased. Meanwhile, the precipitation intensity as reflected by simple daily intensity index (SDII), number of heavy precipitation days (R10), very wet days (R95p), max 1‐day precipitation amount (RX1day) and max 5‐day precipitation amount (RX5day) has also significantly increased. This suggests that the precipitation increase in the arid region is due to the increase in both precipitation frequency and intensity. Trends in extremes are very highly correlated with mean trends of precipitation. The spatial correlation between trends in extremes and trends in the mean is stronger for winter (DJF) than for annual and other seasons. The regional annual and seasonal precipitation and extremes are observed the step jump in mean in the late 1980s. Overall, the results of this study are good indicators of local climate change, which will definitely enhance human mitigation to natural hazards caused by precipitation extremes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

塔里木河下游地下水化学特征对生态输水的动态响应     

陈永金  陈亚宁  刘加珍  LI Weihong  LI Jun  Xu Changchun 《地理学报(英文版)》2005,15(1):13-19

1IntroductionAs an indispensable part of water resource, groundwater plays an important role in ecological environment. Especially in arid and semi-arid area, the changes of groundwater chemistry even determine the ecological process (Ji, 2001; Murgai, 20…  相似文献   

塔里木河中游植物群落的数量分类与分析     

张元明  陈亚宁  张道远 《地理学报(英文版)》2003,13(2):225-232

Plant communities were sampled in the lower reaches of the Tarim River,Xinjiang,The results showed that there are 23 species belonging to 21 genera in 11 families,most of which have low occurrence frequency in quadrats.The most common species is Tamarix ramosissima,which occurred in 17 sites accounting for 89.47% of the total 19 sites,Quantitative classification (TWINSPAN) and ordination(CCA) methods were used to study the distribution Patterns of 23 plant species in 19 sites in this valley.TWINSPAN results showed that the plant communities in the middle reaches of the Tarim River could be divided into 3 groups and the sampling sites could be diveded into 7 types in 3 groups .CCA results were consistent with TWINSPAN results ,and showed species distribution patterns correlated with major environmental variables of groundwater level and soil moisture.  相似文献   

Error assessment of grid-based direct solar radiation models     

Shuhua Zhang  Yaning Chen 《International journal of geographical information science》2013,27(10):1782-1806

This research assessed two grid-based direct solar radiation models, ESRI’s Solar Analyst (SA) and Kumar’s model (KM), using artificial surfaces. Mathematically derived radiation on the surfaces was compared with grid-based model results. While both models showed good consistency with theoretical derivations, they both underestimated direct radiation at daily, most seasonal, and annual scales. KM performed better than SA at all the scales except at annual scale and in the summer. Horizon angle calculation and numerical integration are the common error sources in both models. Interpolation in horizontal angles and the use of a sky size parameter are the additional error sources in SA. Larger errors were found in SA when the sky size parameter and modeling time interval were not compatible. Overall, KM is a better choice for direct solar radiation modeling as it is more accurate and computationally efficient, easier to understand, and needs fewer parameters.  相似文献   

Temporal and spatial variation of water stable isotopes (18O and 2H) in the Kaidu River basin,Northwestern China          下载免费PDF全文

Yun Wang  Yaning Chen  Weihong Li 《水文研究》2014,28(3):653-661

Water resources are the most critical factors to ecology and society in arid basins, such as Kaidu River basin. Isotope technique was convenient to trace this process and reveal the influence from the environment. In this paper, we try to investigate the temporal and spatial characteristics in stable isotope (¹⁸O and ²H) of surface water and groundwater in Kaidu River. Through the water stable isotope composition measurement, spatial and temporal characteristics of deuterium (δ²H) and oxygen 18 (δ¹⁸O) were analysed. It is revealed that (1) comparing the stream water line with the groundwater line and local meteorological water line of Urumqi City, it is found that the contribution of precipitation to surface water in stream runoff is the main source, whereas the surface water is the main source of groundwater. Groundwater is mainly drainage of surface runoff in the river; (2) in the main stream of Kaidu River, the spatial variability of river water showed a ‘heavier‐lighter‐heavier’ change along with the main stream for δ¹⁸O, and temporal variability showed higher in summer and lower in winter; (3) the δ¹⁸O and δ²H values of groundwater samples ranged from ?11.36 to ?7.97‰ and ?73.45 to ?60.05‰, respectively. There is an increasing trend of isotopic values along the groundwater flow path. The seasonal fluctuation of δ¹⁸O is not clear in most samples. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Groundwater depth affects the daily course of gas exchange parameters of Populus euphratica in arid areas     

Yapeng Chen  Yaning Chen  Changchun Xu  Weihong Li 《Environmental Earth Sciences》2012,66(2):433-440

In this case study, the diurnal courses of gas exchange in Populus euphratica at different groundwater depths in the lower reaches of Tarim River were investigated to understand the effects of soil hydrology on photosynthesis and water use efficiency (WUE) of vegetation in arid desert area. It was found that the photosynthetic rate (P _N) was not sensitive to the change of groundwater depth (GD) within the range of 4.2?C6.8?m. Compared to stomatal conductance (g _s) and transpiration rate (E) of P. euphratica grown at GD 4.2, 5.6 and 5.8?m, g _s and E at GD 6.8?m both markedly declined in June, suggesting that P. euphratica at deeper GD can avoid overall water loss by stomatal adjustment. The intrinsic water use efficiency of P. euphratica first decreases with the increasing GD, but when GD increased to 6.8?m, intrinsic WUE increased by 1.2?C2.2 fold, compared with the WUE of P. euphratica at GD 4.2?C5.8?m, indicating that intrinsic WUE of P. euphratica will increase when the plant suffers from moderate drought stress.  相似文献