Preliminary Research On Monitoring Snow Of China With AMSU Data

AMSU (Advanced Microwave Sensor Unit) is a passive microwave sensor carried by NOAA-16. The paper analyzed the spectral characteristic of some kinds of land-surface with the data from the channel 1, 2 and 15 of AMSU, which were sensitive to the land-surface. According to the characteristic of terrain and the others, we divided the territory of China into five areas. For each area, the primary method of monitoring local snow cover with AMSU data was proposed on the basis of microwave remote sensing. With these methods, weekly compositive snow cover maps of China during the period of October 2001 to March 2002 with NOAA-16 AMSU data were achieved.When comparing AMSU snow-cover maps with the conventional observations in the way of point to point, the total discrimination correctness was always higher than 80%, and the no-snow discrimination correctness was around 80%, and most of the snow discrimination correctness (excluding the prior and the posterior of the snow season) was greater than 80%, too. Whether in whole China or in each area of China, the snow, no-snow and total discrimination capabilities of AMSU were better than the other two kinds of the remote sensing results, which were from SSM/I (Special Sensor Microwave Imager) and IMS (Interactive Mapping System) of US. Moreover, the snow cover percentage of AMSU in Xin-Jiang, North-East China and North China were much consistent with that of SSM/I, and were almost consistent with that of conventional observations, but were much close to that of IMS in Tibet Plateau.Some experimental studies were done to monitor the snow depth of Hu-Lun-Bei-Er Grassland with AMSU data. Although some successes were got with statistical correlation between brightness temperature (Tb) and snow depth (SD), there were still some difficulties in accurately monitoring the snow depth of the whole grassland without any ancillary data.At the end, with methods proposed in the paper, snow cover of China during 2002 snow season (from October 2002 to March 2003) were mapped, and were compared with SSM/I and IMS snow-cover map. Simultaneously, snow depths of some cities over Hu-Lun-Bei-Er Grassland were modeled with local SD-Tb correlation and some illustrations were given.