Potential of Using Microwave Emission in Global Analysis of Land Cover and Drought State

Abstract:

The ability to monitor and predict the drought or rainfall in a certain location is indirectly pertinent to the global population. The purpose of this paper is to determine the potential in using microwave brightness temperature and emissivity data to monitor previous droughts and predict future ones. It is known that there is a relationship between the amount of moisture in the Earth’s surface and the microwave emissivity value of that area. Using microwave radiation at various frequencies, satellites sensors such as Advanced Microwave Scanning Radiometer-Earth Observing System(AMSR-E) and Special Sensor Microwave Imager (SSMI) have been collecting data to formulate the emissivity around the globe for the last few decades. Each satellite has gathered data at multiple frequencies and for this study, we focus on the lower frequencies because of their higher sensitivity to surface properties. These lower frequencies tend to be more valid because the signal is emitted from deeper layers in the surface. The Emissivity Microwave Polarization Difference Index (EMPDI) from this data is used and seasonal effects are eliminated by subtracting out the averages of each month. The global EMPDI values for an entire month are then placed in contrast with an independent indicator such as precipitation. Moreover, a drought severity test is performed using techniques that previously were deployed on precipitation data to investigate the potential of using microwave observations in drought monitoring, directly.