东亚夏季风边缘摆动区陆面能量时空分布规律及其与气候环境的关系

东亚夏季风边缘摆动区既是气候敏感区，也是生态脆弱区和农牧交错带，其特殊陆面能量空间分布格局和演变特征对理解该区域天气和气候变化有重要意义。然而受限于陆面观测资料缺乏，对这部分陆面特征的认识仍非常有限。通过对34 a陆面模拟集成产品的分析，发现夏季风边缘摆动区内潜热和感热通量在空间上表现出明显的过渡特征，由摆动区外的相对均衡状态进入到摆动区内的“突变转换”；陆面能量平衡具有明显的区域特征，能量平衡各分量在纬向和经向都表现出了“阶梯型”的变化。就演变而言，区域平均感热和潜热没有表现出规律性的递减或递增趋势，波动幅度在±20%以内，但在20世纪末存在一个较为明显的摆动相位转换:1997年之前夏季风边缘摆动区夏季风相对活跃，潜热通量总体高于其气候值而感热通量则低于其气候值，之后出现了相反的现象。此外，区内感热和潜热通量对气候环境干湿性质非常敏感，两者存在明显的线性关系。 

Spatial-temporal pattern of surface energy fluxes over the East Asian summer monsoon edge area in China and its relationship with climate

The boundary area of the East-Asian summer monsoon in China is an important farming-pastoral ecotone that is ecologically fragile and sensitive to climate changes. The complex geographical, ecological and climatic environment creates an unique spatial pattern and temporal evolution of land surface energy fluxes, which are critical for the understanding of regional weather and climate changes. However, knowledge of characteristics of the land surface process in this region is still very limited due to the lack of sufficient land surface observations. In this study, 34 a of land surface model outputs were analyzed. It is found that the latent and sensible heat fluxes exhibit a significant transition feature in the summer monsoon boundary area with a greater gradient within the boundary area than that outside the area. Surface energy balance displays obvious regional features that are characterized by a "ladder-type" change in the net surface energy flux at both latitudinal and meridional directions. Relatively large radiation and sensible heat fluxes and small latent heat flux are found in the central boundary area. Regional averages of sensible and latent heat fluxes show no regular decreasing or increasing trend with amplitude variations within ±20%. Before 1997, the summer monsoon was relatively active and the latent heat flux in this region was higher than its climatological value while the sensible heat flux was lower than its climatological value; after 1997, the opposite phenomenon was observed. In addition, the sensible and latent heat fluxes are very sensitive to the hydrological component of the climate system, and there exists a significant linear relationship among them.