东北三江平原水稻扩张及其影响区域温度的生物物理机制

Due to human activities and climate change, paddy rice agriculture expanded rapidly in the Sanjiang Plain of Northeast China which has become the new growth pole of the national rice production. The rice expansion has been changing the land surface radiance/energy balance and further affecting temperature. However, the temperature feedbacks to rice expansion and its underlying biophysical mechanism are still unclear. Here we propose to integrate multi-source remote sensing data, cloud computing technology, and phenology-based paddy rice mapping algorithm to track the process and pattern of rice expansion in the Sanjiang Plain since 2000. The potential effects of rice expansion on temperature will be investigated by using both the remote sensing-based land surface temperature data and the in situ observed air temperature data; moreover, the seasonal and diurnal variations of its temperature feedbacks will be examined. The Weather Research and Forecasting (WRF) model will be improved by using the produced rice maps and the MODIS-based land surface parameters (e.g., albedo), and then used to quantify the effects of rice expansion on land surface energy balance and temperature. The temperature feedbacks will be quantified by calculating the radiance/energy flux changes due to rice expansion, as well as the albedo and Evapotranspiration (ET). This project tries to uncover the biophysical effects of rice expansion on temperature. This project expects to improve our understanding on climatic feedbacks of cropping structure changes and to guide the decision-making on agricultural adaptation to climate change.

在人类活动和气候变化共同作用下，东北三江平原水稻面积迅速扩张，成为21世纪以来全国水稻新的增长极。水稻扩张改变地表辐射/能量平衡进而影响区域温度，然而这一强烈的土地利用变化过程对区域温度的影响尚不清楚，其背后生物物理机制有待深入研究。本项目通过多源遥感数据、云计算平台和基于物候的水稻提取算法，刻画2000年以来三江平原水稻扩张的进程；结合遥感和地面观测数据揭示水稻扩张对温度影响的规律，特别是温度响应在昼夜和季节间的差异；在此基础上利用本地化的生物物理参数和更高精度的土地覆盖等下垫面数据来优化WRF模式，模拟水稻扩张对地表辐射/能量和温度的影响，厘定各辐射/能量分量对温度变化的贡献。重点揭示水稻扩张如何通过改变地表反照率和蒸散，进而影响地表辐射/能量平衡并导致区域温度变化的生物物理机制。本研究将为深入认识我国种植结构调整带来的区域气候效应、农业领域应对气候变化的适应措施与对策提供科学依据。

中国东北地区水稻种植面积在人类活动和气候变化共同作用下迅速扩张，这种农业土地利用变化带来的气候效应，特别是通过改变地表辐射/能量平衡进而影响区域温度的生物物理机制仍不清楚。本项目在前期水稻遥感提取工作的基础上，结合遥感大数据和云计算改进和发展了水稻信息提取的新方法，实现了东北地区水稻种植面积的连续监测，并将方法进行改进和拓展到热带地区实现了多云多雨多熟制地区的水稻信息提取，并实现了包括水稻在内的多种主要作物的种植面积监测。在此基础上，结合地面气象观测和遥感地表温度数据，分析了东北地区水稻扩张对区域地表温度影响的规律，揭示了水稻扩张区域温度响应的时空不对称特征；并结合大气甲烷反演数据探究了亚洲季风区典型水稻种植区水稻生长和分布与大气甲烷浓度的时空一致性。研究进一步延伸分析了水稻扩张过程带来的粮食、水、空气质量、人类健康等多维度环境效应及其权衡和协同关系。本研究将为深入认识种植结构调整带来的环境效应、农业应对气候变化等决策提供科学依据。

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