基于BEPS生态模型对亚洲东部地区蒸散量的模拟

气候变化和人类活动的加剧导致亚洲东部地区陆地生态系统的碳水循环过程发生显著的变化,成为全球变化研究最关注的对象之一。实际蒸散(ET)是陆地生态系统碳水循环的重要组成部分,但对该地区ET特征的研究尚不够深入。论文利用遥感、气象和土壤等资料驱动生态过程模型BEPS对亚洲东部地区1982—2006年间的ET进行了模拟分析。利用6个站的通量实测数据验证表明,BEPS模型能够解释ET的81.23%的年变化和86.4%的10 d变化。模拟结果表明:亚洲东部的ET呈现出从东南向西北和西南沙漠地区逐渐减少的分布特征,最小值位于中国的西北沙漠地区;ET与降水量之比从东南和东北地区向西北内陆和西南沙漠地区逐渐增加,其中在中国长江以南的亚洲东部地区,平均值为0.4,而在沙漠地区接近1.0。在1982至2006年期间,研究区年ET总量的平均值为12 045×109m3/a,其中,中国、泛东南亚和印度的ET总量占整个研究区的62.4%;研究区的单位面积ET均值为401 mm/a,在泛东南亚地区最大(1100 mm/a),在蒙古最小(134 mm/a)。在所有的地表覆盖类型中,常绿阔叶林的ET总量和平均值都为最大,城镇地区的ET总量和平均值都为最小。研究区的ET总量呈增加趋势,草地、稀树草原、裸地和城镇的ET明显上升,其它地表覆盖类型的ET变化不明显。

Study on Evapotranspiration in East Asia Using the BEPS Ecological Model

East Asia is one of the most complicated and disputed areas of carbon and water cycles due to the integrated effect of variable climate and intense human disturbances. Evapotranspiration (ET) is an important component of the carbon-water cycle; however, regional studies of ET in East Asia are still few. This study is to analyze the spatio-temporal distributions of ET in East Asia during 1982 to 2006 using the process-based ecological model BEPS, which was driven by meteorological, soil and remote sensing data at an 8-km resolution. Prior to the regional simulation, BEPS was validated using measured ET in six typical forest ecosystems. BEPS can explain 81.23% of the annual ET and 86.4% of the 10-day ET variations, respectively, indicating that BEPS can accurately simulate ET in East Asia. Simulated annual ET in East Asia shows a gradually decreasing pattern from the southeast and northeast regions to the northwest and southwest desert areas, with the smallest values in the northwestern desert region of China. It also shows that the ratio of ET and precipitation was increasing from the southeast and northeast regions with an average of 0.4 to the northwest and southwest desert region with the values greater than 1.0. The annual total ET in East Asia averaged from 1982 to 2006 was 12045 ×10⁹ m³/a, and China, Pan Southeast Asia and India accounted for 62.4% of the annual total ET. Mean ET per unit area of the study area was 401 mm/a, with the largest values in Pan Southeast Asia (1100 mm/a), and the smallest values in Mongolia (134 mm/a). Relative to the different land cover types, the maximum of the total and mean ET values were the evergreen broad-leaved forests, while the minimum values were both in urban and built-up areas. The whole East Asia region showed a significant increasing trend in ET. Grasslands, savannas, bare land and urban land marked a noticeable increasing trend of ET, yet other vegetation types did not change significantly.