基于GLEAM模型的淮河流域地表蒸散量时空变化特征

蒸散发是连接地表水循环和能量循环的纽带,淮河流域地表蒸散量的时空变化分析对深入理解中国气候过渡带水循环对全球变化的响应具有重要价值。该文基于流域水量平衡原理,利用流域水文数据对淮河流域GLEAM产品进行精度验证;并利用GLEAM(global land-surface evaporation:the Amsterdam methodology)产品分析1980-2011年淮河流域地表蒸散发年际和年内的时空变化。结果表明:1)淮河流域及其水资源二级分区的降水实测值与GLEAM产品估算结果比较,平均相对偏差为8.0%,相关系数高达0.94,GLEAM产品对于淮河流域的模拟精度较高;2)淮河流域1980-2011年多年平均年地表蒸散量为673 mm;3)淮河流域多年平均年地表蒸散量空间变化范围为528~848 mm,空间差异显著,呈从西南向东北逐渐减少,淮河以南地表蒸散量大于淮河以北地表蒸散量,四个季节地表蒸散发具有类似的空间分布特征;4)近32 a淮河流域平均的年地表蒸散量变化范围为588.6~767.8 mm,且存在显著的上升趋势;地表蒸散量的季节变化大致呈单峰型分布,峰值出现在8月,最小值出现在12月;且季节变化较为明显,夏季(272.0 mm)春季(191.4 mm)秋季(144.3 mm)冬季(65.0 mm);5)基于栅格尺度年地表蒸散量的变化速率主要受春季主导,依次为夏季、秋季,冬季的影响最小,淮河流域大部分区域地表蒸散发量呈增加趋势。该研究可为淮河流域洪涝、干旱等极端水文气象事件的监测与预警提供科学依据,同时为该流域水资源管理提供参考及决策依据。

Spatial and temporal changing analysis of terrestrial evapotranspiration in Huai River basin based on GLEAM data

Abstract: Terrestrial evapotranspiration (ET) connects land water cycle with land energy cycle. Analysis of the spatio-temporal of ET in Huai River basin helps us understand the response of water cycle in Chinese climate transition zone to global climate change and provide some valuable information for prediction of the change of water resource in that region in the future. Based on water balance model in Huai River basin, this study validated the accuracy and applicability of ET data from Global Land-surface Evaporation: the Amsterdam Methodology (GLEAM) using hydrological data. In addition, we also analyzed the interannual spatio-temporal variation of yearly and seasonal ET and the annual cycle of the monthly and daily ET in the Huai River basin during the period from 1980 to 2011 using GLEAM ET data. Results showed that: 1) Compared to the observed precipitation, the precipitation estimated by GLEAM ET data had lower mean relative error (MRE 8.0%) and the high correlation coefficient (0.94); The GLEAM data showed a high capacity of reflecting the magnitudes and spatial pattern of basin-scale ET in Huai River basin; 2) The mean annual ET of Huai River basin was 673 mm during the period of 1980-2011; 3) GLEAM model showed that the spatial variation of mean annual ET value ranged from 528 to 848 mm during the period from January 1, 1980 to December 31, 2011 over Huai River basin, which had a significant difference in spatial patterns; GLEAM model also showed that spatial patterns of mean annual ET decreased from the southwest to the northeast part of Huai River basin and that the mean annual ET in the southern region of Huai River was greater than in the northern region of Huai River; The mean seasonal ET had similar spatial pattern with the mean annual ET using the GLEAM ET data over the Huai River basin; 4) the domain-averaged annual ET in Huai River basin varied from 588.6 to 767.8 mm and showed a prominent increasing tendency for the period of 1980-2011; The GLEAM ET data showed a strong seasonality of ET in Huai River basin with the maxima in August and the minima in December; Among four seasons, the summer ET was the largest with the value of 272.0 mm, followed by the spring(191.4 mm) and autumn (144.3 mm); The smallest value was 65.0 mm in winter; 5) Spatial distribution of annual change rate of ET during 1980 to 2011 in Huai River basin every 10 years based on grid scale for all of Huai River basin was dominated by the change rate of ET in spring, followed by that in summer and autumn. The effect of ET changing rate in winter on annual ET was quite weak. Annual ET in most area over Huai River basin had an increasing tendency. Overall, this study can provide valuble information for monitoring and forecasting extreme hydrometeorological events, such as flood and drought. It also can provide decision-making reference for water resource management in Huai River basin.