河西走廊大型风电场局地气候效应及其对荒漠植物的影响

To mitigate global warming, wind energy as an important clean energy has been widely used in the world. A large number of wind farms have been set up and run in past few decades, which have achieved remarkable results. However the rotation of the turbine on the wind farms changes the stability of the near-surface atmosphere and enhances the vertical mixing. It results in significant warming effects and regional climate effects (RCE). In recent years, many large-scale wind farms have been constructed on Gobi desert from east to west in arid areas of Hexi corridor. The RCE of the wind farms would be bound to break the fragile stability of the desert ecosystem over there and affect the ecological function of the anti-sand belt in Hexi corridor, which is the key functional area of national ecological security. Based on the inversion of remote sensing data to extract the land surface temperature (LST) information of Hexi Corridor in the past 20 years, and combined with field located observation, on time scale, we will compare and analyze the process of the LST changes, the temperature difference, the temperature increase range and the regional climate of the inside and outside of the farms area before and after the wind farms operated, and analyze compare with its adjacent oasis simultaneously. Also on spatial scale, we will study the impact spatial extent scope of its "heat island effect" and the RCE. Meanwhile, we will study the impacts of the RCE on desert plants with different drought-resistance strategies from three levels of plant, population and community. And then we will evaluate its impact on the desert ecological system and ecological function of Hexi Corridor. Finally, the project will provide the scientific basis for the scientific operation of wind farms, coping with global climate change and safeguarding national ecological security decision-making.

为减缓全球变暖，风能作为重要的清洁能源在全球得到了广泛利用，大批风电场的建设运行取得了显著的效果。但风电场上涡轮机的转动改变了近地面大气层稳定性，加强了垂直混合，引起了明显的增温效应与局地气候效应。近年来河西走廊从东到西在荒漠戈壁上建设了一大批大规模风电场，其局地气候效应势必会打破这里荒漠生态系统原本脆弱的稳定性，影响到国家生态安全重点功能区河西走廊防沙带生态功能的发挥。项目基于遥感数据反演，提取近二十年来地表温度信息，结合实地定位观测，从时间尺度上对比分析风电场运行前后电场内部、外部及相邻绿洲的地表温度变化过程、温度差异、增温幅度及局地气候；从空间尺度上研究其“热岛效应”与局地气候效应影响的空间范围；从单株、种群和群落三个层次分析其气候效应对不同抗旱策略类型荒漠植物的影响，评估其对河西走廊荒漠生态系统及生态功能的影响，为风电场科学运行、应对全球气候变化和维护国家生态安全决策提供科学依据。

本项目通过实地观测与遥感信息提取，研究了河西走廊戈壁荒漠上大型风电场气候效应时空变化过程，分析了其对河西走廊荒漠植物的影响。风电场运行导致电场区域和下风向近地面风速降低，风电场运行时电场区域夜间有一定的增温效应。风电场近地层3m范围风速表现为上风向>电场中>下风向，电场内和下风向的风速分别是上风向的87.3%和63.2%，风穿过电场后风速减少了36.8%。风机运行时段近地层0.5~3.0m气温夜间在电场区域有局地增温效应，春季在凌晨04:30时至次日上午10:40时电场区域显示有明显的增温效应，电场内比上风向高0.71℃，比下风向高0.87℃；夏季在凌晨2:30时至上午09:00时有更加明显的增温效应，电场内部比上风向高1.47℃，比下风向高2.0℃；秋季在凌晨0:00时至上午11:00时电场中显示有一定的增温效应，电场内部比上风向高0.51℃，比下风向高1.77℃；冬季电场区域未显示有增温效应。风电场运行后，电场区与对照区之间的LST温差逐年增高。在玉门荒漠草原风电场、民勤干旱荒漠风电场和瓜州极旱荒漠风电场，电场区与对照区的年均LST温差建设运行后比建设运行前分别升高了0.65℃、0.50℃和0.14℃。随着风电场运行年代的延长，这种增温效应呈现缓慢上升的趋势，这种增温趋势在玉门荒漠草原风电场和民勤干旱荒漠风电场较为明显，而在瓜州极旱荒漠风电场趋势较弱。风电场增温效应对植物生长的促进作用在降水量相对较高、干燥度相对较低的玉门荒漠草原风电场效果较为明显；在降水量相对较低、干燥度较高的民勤干旱荒漠风电场较弱；而在极度干旱的瓜州极旱荒漠风电场基本没有影响。风电场增温效应对荒漠草地生物多样性仅仅对荒漠草原优势种有微弱影响，对干旱荒漠和极旱荒漠基本没有影响。