极端干旱荒漠区湿地碳、水热通量变化特征及其对环境因子响应的观测 和数值模拟研究

As a special type of underlying surface, the long-term measurements of Land-Atmosphere substance and energy exchanges in the wetland of extremely arid desert areas are essential to deeply understand climate change over arid areas, which is also conducive to knowing carbon balance, hydro-thermal circulation and regional climate change on a global scale. In present, long-term observation data on carbon, water and heat fluxes in the wetland ecosystem of extremely arid desert areas is less compared with that in other underlying surface, which limits greatly.the study on land surface processes and climate change in arid areas. Based on the continuous measurements of carbon, water and heat fluxes in Xihu Desert Wetland, Dunhuang, the regional carbon circulation and transport characteristics of sensible and latent heat fluxes in varying time scale will be analyzed to better discuss surface energy balance characteristics and evaluate carbon source/sink capacity. Combined with the environmental factors such as soil temperature and humidity, soil heat flux and some meteorological parameter near land surface, the mechanism of action between carbon, water and heat fluxes and main environmental factors will be revealed over the wetland of extremely arid desert areas, which will deeply understand Land-Atmosphere substance and energy exchange mechanism over the special underlying surface of arid areas. The characteristics and differences of carbon and water heat fluxes between wetlands and gobi and oasis in arid areas were studied. The project will enrich the land-surface process observation network over typical underlying surface of arid areas by longterm measurements of carbon, water and heat fluxes over the wetland of extremely arid desert areas, which will provide fundamental data to development of land-surface models over arid areas and also will give some scientific basis on wetland restoration in arid areas.

作为极端干旱区一种特殊下垫面，对荒漠区湿地陆-气间物质与能量交换过程的长期监测，是认识干旱区气候变化的数据基础，对全球范围内的碳平衡、水热循环和区域气候变化研究有重要科学意义。目前，极端干旱区荒漠湿地碳和水热通量的长期观测资料较匮乏，这极大地限制了干旱区陆面过程与气候变化方面的研究。本项目基于涡动相关法对敦煌西湖湿地碳和水热通量的连续观测资料，分析该区域不同时间尺度碳循环以及感热、潜热输送特征；探讨地表能量平衡特征以及评估碳源/汇能力；结合土壤和气象要素数据，揭示荒漠区湿地碳和水热通量与环境因子间的作用机制；最后，对比研究干旱区湿地与戈壁和绿洲碳和水热通量变化特征及其差异。加深对该区域陆-气间物质与能量交换过程的认识。本项目通过对荒漠区湿地碳和水热通量的分析、模拟和对比研究，丰富了干旱区典型下垫面陆面过程的观测网络，为干旱区陆面模式的改进提供验证数据，同时也为干旱区湿地修复提供科学依据。

敦煌西湖荒漠区湿地位于中国西北的极端干旱区，保护区湿地面积11.35万公顷，其中芦苇沼泽3.428万公顷，是我国西北地区面积较大的芦苇沼泽之一，周围分布着戈壁、荒漠、沼泽和盐湖等，其下垫面特征与单纯的荒漠或湿地生态系统差异显著，在中国以及全球范围内都具有十分重要的独特性，是开展荒漠区湿地生态系统各项研究的天然实验室，然而由于当地环境条件的限制，长期以来缺乏对该地区CO2和水热通量的长期连续有效观测。本项目对该区的碳、水热通量及其环境要素进行了长期连续定位观测。评估极端干旱区荒漠区湿地生态系统的碳源/汇能力；探求了该地区的辐射通量的变化特征；通过敦煌湿地、戈壁、沙漠和绿洲的对比研究阐明极端干旱荒漠区湿地气象因子变化特征的差异性。本项目的实施将丰富干旱区典型下垫面陆面过程的观测网络，深入分析这一地区的陆-气相互作用特征和影响因素对维护敦煌绿洲的持久稳定、保护世界文化遗产-莫高窟和改善敦煌及其周边区域生态环境等方面都具有极其重要的意义。