| The world has been experiencing the climate warming. Extreme drought caused by climate warming has become one of the major issues of worldwide concern. The total grain yield of Huaihe basin takes up1/6of that in the whole country, providing commodity grain which accounts for about1/4, which makes it one of the important bases of agricultural products in china. Drought is one of the main limitations restricting the development of agricultural production in this area. Therefore, real-time drought monitoring studies have long-term significance on climate change, drought defense, and water resources management and protection issues. Now, there are two main types of drought monitoring methods that are widely used at home and abroad:one is the traditional method, which is based on the single observation point to construct the drought index. But it’s very difficult to effectively reflect the drought conditions. The other one is the use of modern satellite remote sensing technology, using multi-temporal, multi-spectral, multi-angle remote sensing data from different aspects of qualitative or quantitative evaluation of soil moisture distribution, which is very important for the wide drought monitoring.AMSR-E is a total energy of passive microwave radiometer, which can be used for all-weather uninterrupted observations. AMSR-E can not only provide various parameters of land, ocean and atmosphere, but can also obtain land surface soil moisture products based on global. It will be of great help for improving the efficiency of agricultural production in the basin to combine this new method of data acquisition with the new index calculation method and apply them to the drought monitoring and prediction.On the foundation of the previous work at home and abroad, this research takes Huaihe River Basin as an example. The research is based on AMSR-E vertical and horizontal polarization mode’s5band passive microwave remote sensing, totally10data from2006to2010. The research uses microwave polarization difference (MPDI) drought index to preliminary select the frequency for Huaihe basin arid study by comparing to the measured soil moisture. And it analyses the relationships among the MPDI, SPI and AMSR-E Soil Moisture Product. Finally reaches the following conclusions:1. This paper gets the time series correlation coefficient for the10sites of Huaihe basin by program calculating the measured soil moisture data and the constructed MPDI drought index, and also gets maps of the correlation coefficient distribution. In general, the coefficient has a good negative correlation to the measured soil moisture. Therefore, the MPDI drought index is fit for the drought study to Huaihe basin.2. It can obtain the time sequence diagram in each site of MPDI drought index and the daily precipitation and the SPI drought index by calculating and analyzing the time series relationship of the10sites between the MPDI drought index and daily precipitation and the SPI value. Among them,6.9GHz and18.7GHz frequencies of the MPDI index in each site are relatively more consistent with the measured rainfall and the SPI drought index, and can more fully reflect the drought situation in each sites. So the two frequencies of MPDI drought index are much suitable for the research of drought in Huaihe basin.3. Through the comparative analysis of the two optimized frequencies of MPDI drought index and AMSR-E soil water products in the Soil Moisture, the AMSR-E soil water products in the Soil Moisture is in a good correlation with the amount of precipitation, however which is in poor correlation with the SPI drought index value in Huaihe basin. The calculation method of preferred two the frequency of the MPDI drought index is simpler, and the amount of precipitation, the standardized precipitation index correlates better with the actual drought occurrence in Huaihe River Basin, which are more suitable for the research of drought in Huaihe basin.4. The frequency of MPDI drought index in the spatial distribution of the overall trend is consistent with that of measured soil moisture. But there still exist some differences in the drought degree between them, especially in severe drought regions.In short, the microwave polarization difference index of brightness temperature data and anomaly microwave polarization difference index are useful for monitoring drought of Huaihe River basin, which have a certain value for drought monitoring and prevention of Huaihe basin. |
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