1. Institute of Meteorology and Ocean; PLA Univ. of Sci. & Tech.; Nanjing 211101 China
2. Polar Research Institute of China; Shanghai 200136 China
3. School of Space Science and Physics; Shandong University; Weihai Shandong 264209 China
4. Unit No. 61741 of PLA; Beijing 100094 China
5. Unit No. 63655 of PLA; Wulumuqi 841700 China