Multi-frequency and multi-temporal SSM/I data analysis in China

The technique is developed to analyze the seasonal changes of land cover in China using multi-channel and multi-temporal brightness temperature data from SSM/I spaceborne microwave radiometry. The concept of normalized difference polarization index (NDPI) is put forward based on analysis in applications of spaceborne microwave radiometer data. SSM/I multi-channel data acquired in April and July of 1997 (data of the 20/sup th/ and 24/sup th/ in each month) with three month interval are processed. As a result, the land NDPI map of China is produced. Further more, the temporal changes of land cover characteristics is studied. The results show that different types of land covers have their own characteristic NDPI, and their NDPI changes with time. Vegetation and water content are the main factors causing NDPI change. The study shows the power of spaceborne passive microwave remote sensing for global change monitoring.