基于多源卫星遥感的气象干旱及其对植被的影响研究

Drought is the most common and the costliest natural disaster over northern China. Accurate monitoring of regional meteorological drought and its impact on vegetation is essential for practical purpose; meanwhile, it is an important scientific issue of climate change and regional responses. To date, studies have been mainly based on investigating meteorological drought and its impact using meteorological data, but the usage of satellite remote sensing data is still limited. This study focused on monitoring regional drought and its impact on vegetation by using multi-sensor satellite based Microwave Integrated Drought Index (MIDI), which was developed by the proposer, over northern China cropland and grassland which suffered drought frequently. The MIDI can consistently and continuously monitor drought cross space and time in all weather conditions. Comparisons will be conducted between MIDI and different time scales Standardized Precipitation Index (SPI), which can estimate drought conditions with high accuracy deriving from the in-situ precipitation data, to assess the capability of MIDI in monitoring meteorological drought at different time scales over space and time. Furthermore, optimal weights of MIDI variables will be selected for monitoring different time scales meteorological drought from region to region. Then drought characteristics of MIDI including the spatial pattern and time variation will be extracted and further compared with the variation of Normalized Difference Vegetation Index (NDVI), to investigate the mechanism of meteorological drought induced vegetation failure. The study is expected to improve meteorological drought monitoring and impact assessment, and will provide valuable information for drought early warning and risk management of water resources and agricultural production.

干旱是我国北方最常见、影响最大的自然灾害。区域气象干旱的准确监测及其对植被的影响研究，是我国气象灾害研究的迫切需求，也是气候变化区域研究的重要科学命题。但目前主要集中于利用气象观测资料研究以上问题，基于遥感的研究是一个薄弱环节。本项目拟利用多源卫星遥感资料，充分利用卫星遥感在空间观测及微波遥感全天候工作的优势，开展我国北方草地和农田区域，气象干旱及其对植被的影响研究。通过由项目申请人已经提出的微波集成干旱指数（MIDI），结合基于气象观测资料的标准化降水指数（SPI）准确性高的特点，开展遥感及气象资料干旱指数的对比研究，系统评估并获得区域适应的不同时间尺度微波集成干旱指数；进一步构建研究区域气象干旱空间图像，获取气象干旱空间分布与时间变化特征，揭示不同时间尺度、不同程度气象干旱对植被(NDVI)的致灾过程及机理。期望为防灾减灾、干旱的合理应对提供科学依据和决策参考。

干旱是我国北方最常见、影响最大的自然灾害。区域气象干旱的准确监测及其对植被的影响研究，是我国气象灾害研究的迫切需求，也是气候变化区域研究的重要科学命题。本研究充分利用了卫星遥感在空间观测及微波遥感全天候工作的优势，结合基于气象观测资料的标准化降水指数（SPI）准确性高的特点，开展遥感及气象资料干旱指数的对比研究，建立了区域（格点）适应的1，3和6个月的微波集成干旱指数（MIDI），并构建了气象干旱数据集。进一步获取了气象干旱空间分布与时间变化特征，其中6个月MIDI的干旱范围与较短尺度MIDI相比更集中。揭示了不同时间尺度气象干旱（MIDI）对植被(NDVI)的致灾特征，发现更长时间尺度的（6个月）MIDI对植被的影响最直接和显著，同时在人类活动干预少的地区效果更有效。在完成预设研究任务的基础上，将研究区域从我国北方半干旱地区扩展到了全球半干旱地区，对比分析了全球半干旱地区近年来干旱和植被变化的特征，并揭示了ENSO对全球半干旱地区干旱和植被变化的反向控制特征（ENSO正相关于北半球干旱和植被状况，负相关于南半球干旱和植被状况）。本研究对提高我国北方地区基于遥感的气象干旱及其影响研究有现实意义，同时研究有助于加深海温变化与半干旱地区生态系统联系的认识。