SAR monitoring of Sea ice evolution in main China offshore sea ice regions
Yonggang JI(1) and Jie ZHANG(2)
Institute of Oceanology, Chinese Academy of Scienc,
No.7 Nanhai Road,
(2) First Institute of Oceanography,SOA, XianXialing road No.6, 266061,Qingdao, China
The Liaodong bay in Bohai Sea is the main China offshore sea ice region; the first task of the operational sea ice monitoring is boundary identification between ice and water and its evolution monitoring. In this paper, we collected 6 scenes SAR imageries at five different times of the Liaodong bay from the beginning of January to the end of February, which include 5 scenes alternating polarisation Envisat ASAR imageries (AP Image Mode) obtained on Jan 11, Jan 24, Feb 9 and 12 (2 sceneries) respectively and another one scene ERS-2 SAR imagery obtained on Feb 25. Sea ice was found in all of these SAR imageries, and both the boundary between the ice and the water and the boundary between the ice and the land of this region are clearly, which changed with time. The texture features and polarization features of SAR imageries were used to classify sea ice, sea water and land at five different times, and the boundaries of them were extracted. Then the results were compared with those obtained from MODIS data. It can be found that the results using alternating polarisation Envisat ASAR imagery are better than that of using single-polarized ERS-2 SAR data in discriminating ice and water. Integrated with MODIS, AMSR-E, some other remote sensing data and meteorological data, these SAR imageries were used to study the changes of the boundaries between ice and water and the changes of the distance from the boundary line to the land. Then the temporal evolution of the Liaodong bay sea ice in 2004-2005 winter was described quantitatively.