西南地区秋季干旱的年代际转折及其可能原因分析   总被引：2，自引：0，他引：2  

张顾炜  曾刚  倪东鸿  周国兵 《大气科学》2016,40(2):311-323

采用1961~2012年中国气象局753站降水和温度资料、NCEP/NCAR全球大气再分析资料、NOAA海表温度资料等,应用观测统计分析和全球大气环流模式NCAR CAM5.1数值模拟,基于标准化降水蒸散指数(SPEI),对我国西南秋季干旱的年代际转折及其可能原因进行了分析。观测分析结果表明:(1)西南秋季干旱的主要分布型为全区一致型;西南秋季SPEI在1994年发生年代际突变,突变后(前)为偏旱(涝)期。(2)西南秋季偏旱期的主要环流特征是,西太平洋副热带高压位置偏西、面积偏大、强度偏强,南支槽偏弱,西南地区存在下沉运动。(3)热带东印度洋-西太平洋的海表温度年代际升高对西南秋季SPEI在1994年发生年代际突变有重要作用,该关键海区海表温度异常升高,一是会使秋季西南地区500 hPa高度场偏高,南支槽减弱;二是产生偏强的Hadley环流,使得我国西南地区存在下沉运动;三是会在西太平洋激发气旋性环流,使我国西南地区被偏北气流控制,削弱了向我国西南地区的水汽输送,容易造成该地区的秋季干旱。应用NCAR CAM5.1全球大气环流模式进行了关键海区海表温度年代际变化的敏感性试验,验证了观测分析结果,即秋季关键海区海表温度年代际升高对西南秋季年代际变旱有重要作用。  相似文献   

An analysis of soil moisture dynamics using multi-year data from a network of micrometeorological observation sites   总被引：4，自引：0，他引：4  

Gretchen R. Miller  Dennis D. Baldocchi  Beverly E. Law  Tilden Meyers 《Advances in water resources》2007

Soil moisture data, obtained from four AmeriFlux sites in the US, were examined using an ecohydrological framework. Sites were selected for the analysis to provide a range of plant functional type, climate, soil particle size distribution, and time series of data spanning a minimum of two growing seasons. Soil moisture trends revealed the importance of measuring water content at several depths throughout the rooting zone; soil moisture at the surface (0–10 cm) was approximately 20–30% less than that at 50–60 cm. A modified soil moisture dynamics model was used to generate soil moisture probability density functions at each site. Model calibration results demonstrated that the commonly used soil matric potential values for finding the vegetation stress point and field content may not be appropriate, particularly for vegetation adapted to a water-controlled environment. Projections of future soil moisture patterns suggest that two of the four sites will become severely stressed by climate change induced alterations to the precipitation regime.  相似文献   

柽柳灌丛热量收支特性与蒸散研究   总被引：5，自引：1，他引：5  

张小由  龚家栋  周茂先  司建华 《高原气象》2004,23(2):228-232

Bowen能量平衡法是广泛用于测定各种低矮植物蒸散的常用方法。本文将改进的波文比—能量观测系统用于测定灌木柽柳群落的测定，通过6～9月对感热通量、潜热通量、土壤热通量等的测定，计算出额济纳地区柽柳灌丛(6～9月)的蒸散量为335．31mm；在8月潜热通量占能量支出量的62．85％，感热通量占32．85％，土壤热通量占4．44％。在日变化中，潜热在上午大于感热，下午感热交换大于潜热。  相似文献   

基于SPEI的辽西地区气象干旱时空分布特征     

何鑫  吴吉东  李颖  冯玉 《干旱区地理》2017,40(2):340-347

干旱是辽西地区最为频繁的自然灾害之一,已严重制约人们的生活和经济发展。以辽宁省西部作为研究区域,借助该区8个气象站点1960-2015年逐月气温、降水数据,计算年、季、月时间尺度的标准化降水蒸散指数（SPEI）,并进行Mann-Kendall 趋势变化和ArcGIS空间可视化分析,揭示了辽西地区近56a气象干旱的时间变化趋势,以及干旱频率和干旱强度的空间分布特征。结果表明：近56a辽西地区干旱发生频率呈现上升趋势,尤其是21世纪以来;季节干旱变化趋势不甚明显,各季节均有干旱发生,其中秋季干旱最严重;辽西各地区均有干旱发生,在年尺度、季尺度和月尺度下发生频率分布不均,总体呈西部频率高东部频率低的趋势;21世纪以来发生连续干旱次数较多,干旱发生强度呈现西南强,东北弱的分布特征,高值中心在建平。  相似文献   

Responses of water use efficiency to phenology in typical subtropical forest ecosystems——A case study in Zhejiang Province     

Fengsheng GUO  Jiaxin JIN  Bin YONG  Ying WANG  Hong JIANG 《中国科学:地球科学(英文版)》2020,63(1):145-156

Ecosystem-scale water-use efficiency(WUE) is an important indicator for understanding the intimately coupled relationship between carbon and water cycles in ecosystems. Previous studies have suggested that both abiotic and biotic factors have significant effects on WUE in forest ecosystems. However, responses of WUE to phenology in the context of climate change remain poorly understood. In this study, we analyzed the sensitivity and response patterns of seasonal WUE to phenology in Zhejiang Province where typical subtropical forest ecosystems are located, and discussed potential causes of the changes of the sensitivity and response patterns along different climate gradient during 2000–2014. The results of interannual partial correlation analysis showed widespread negative correlations between WUE and the start of growing season(SOS) in spring. This is because the increase in gross primary product(GPP) is larger than that of evapotranspiration(ET), resulting from an advanced SOS. The positive correlation between WUE and SOS was widely observed in summer mainly because of water stress and plant ecological strategy. The autumn WUE enhanced with the delay in the end of growing season(EOS)mainly because of the increase in GPP meanwhile the decrease or steadiness in ET, resulting from a delayed EOS. In space, the sensitivity of spring WUE to SOS significantly decreased along the radiation gradient, which might be related to strong soil evaporation in high radiation area;the sensitivity of WUE to SOS in summer showed a positive correlation with precipitation and a negative correlation with temperature, respectively, which might be attributed to the compensation of GPP to the delayed SOS and water stress caused by high temperature. The sensitivity of WUE to EOS increased significantly along the radiation and precipitation gradients in autumn, which may be because the increase of radiation and precipitation provides more water and energy for photosynthesis.  相似文献   

Sensitivity and uncertainty quantification for the ECOSTRESS evapotranspiration algorithm – DisALEXI     

《International Journal of Applied Earth Observation and Geoinformation》2020

  相似文献   

Predicting runoff in ungauged catchments by using Xinanjiang model with MODIS leaf area index   总被引：6，自引：0，他引：6  

Hongxia Li  Yongqiang Zhang  Francis H.S. Chiew  Shiguo Xu 《Journal of Hydrology》2009,370(1-4):155-162

Vegetation processes are seldom considered in lumped conceptual rainfall–runoff (RR) models although they have significant impacts on runoff via the control of evapotranspiration. This paper incorporates the remotely-sensed the moderate resolution imaging spectrometer mounted on the polar-orbiting terra satellite-leaf area index (MODIS-LAI) data into Xinanjiang rainfall–runoff model and assesses the model performance on 210 catchments in south-east Australia. The results show that the inclusion of LAI data improves both the model calibration results as well as the daily runoff prediction in ungauged catchments. It is likely that more significant improvements to the model structure to integrate the remotely-sensed vegetation and other data can further reduce the uncertainty in runoff prediction in ungauged catchments.  相似文献   

Assessing the impact of interannual variability of precipitation and potential evaporation on evapotranspiration     

《Advances in water resources》2014

The impact of interannual variability of precipitation and potential evaporation on the long-term mean annual evapotranspiration as well as on the interannual variability of evapotranspiration is studied using a stochastic soil moisture model within the Budyko framework. Results indicate that given the same long-term mean annual precipitation and potential evaporation, including interannual variability of precipitation and potential evaporation reduces the long-term mean annual evapotranspiration. This reduction effect is mostly prominent when the dryness index (i.e., the ratio of potential evaporation to precipitation) is within the range from 0.5 to 2. The maximum reductions in the evaporation ratio (i.e., the ratio of evapotranspiration to precipitation) can reach 8–10% for a range of coefficient of variation (CV) values for precipitation and potential evaporation. The relations between the maximum reductions and the CV values of precipitation and potential evaporation follow power laws. Hence the larger the interannual variability of precipitation and potential evaporation becomes, the larger the reductions in the evaporation ratio will be. The inclusion of interannual variability of precipitation and potential evaporation also increases the interannual variability of evapotranspiration. It is found that the interannual variability of daily rainfall depth and that of the frequency of daily rainfall events have quantitatively different impacts on the interannual variability of evapotranspiration; and they also interact differently with the interannual variability of potential evaporation. The results presented in this study demonstrate the importance of understanding the role of interannual variability of precipitation and potential evaporation in land surface hydrology under a warming climate.  相似文献   

Physico‐Chemical and Bacterial Characteristics of Water Quality in Three Villages West of Lake Nasser,Egypt     

Mohamed Nageeb Rashed  Magdy Younis 《洁净——土壤、空气、水》2012,40(11):1229-1235

The present study aims to investigate physico‐chemical and bacterial characteristics of Nasser Lake water and houses drinking water, as well as fish cultures and its wastewater, in three villages west of Lake Nasser, Egypt. Fifteen representative water samples (Nasser Lake, different drinking water, fish cultures, and wastewater sources) were collected from three villages (Garf Hussein, Bashaier, and Kalabsha) in the west of Lake Nasser. Physico‐chemical, total viable counts, and bacterial qualification of water were achieved. The obtained results indicated that the produced water, supposed to be for domestic use in the three villages, contained all the tested organisms. The investigated water samples of the lake and drinking water in the selected three villages are supposed to be chemically safe according to World Health Organization and to Egyptian standards for drinking water. Water pollution index (WPI) was used in this study and the result concluded that for irrigation canals from the lake to the agriculture site, fish cultures (both concrete and earth pond systems), and drainage canal of fish ponds need to be treated before it is discharged to the lake. It is better to reuse it after treatment for agricultural purposes or recycled it to the fish cultures.  相似文献   

应用MODIS数据推估区域地表蒸散   总被引：4，自引：1，他引：3       下载免费PDF全文

刘朝顺  高炜  高志强 《水科学进展》2009,20(6):782-788

通过"热增强"方法,充分利用MODIS数据的时间分辨率和空间分辨率的优势,基于对SEBAL模型改进的基础上,反演并验证了山东省的地表蒸散。结果表明,蒸散反演结果与实测值具有很好的一致性,日平均相对误差约为-11.34%。同时分析了研究区2005年和2006年不同土地利用/覆盖类型下蒸散的逐月变化规律,发现水域的月平均蒸散量最大,其次为水田,林地、旱田和草地基本相当,人工用地的月平均蒸散量最小。  相似文献