利用COSMIC掩星折射率数据研究中国陆地区域对流层顶高度的时空特征

Spatial-Temporal Characteristics of the Tropopause Height over Land Area of China with COSMIC Radio Occultation Refractivity

利用折射率协方差变换法采用2007-2014年COSMIC(Constellation Observing System for Meteorology,Ionosphere and Climate)掩星观测数据研究了中国陆地区域对流层顶高度的时空变化特征。实验结果表明:中国陆地区域的对流层顶高度随纬度变化,呈现出"南高北低"的格局;而对流层顶处的温度和压强分布与高度分布相反。同时,中国陆地区域内对流层顶高度表现出较强的季节相关性,中国大部分陆地地区通常夏季对流层顶最高,冬季对流层顶最低;但在低纬地区(16°N^26°N)表现相反。在30°N^40°N之间的亚热带区域四季的变化较为显著,且存在明显的等值线。采用中位数斜率回归法分析了2007-2014年中国陆地区域对流层顶高度的年际变化,发现中国陆地区域对流层顶高度平均每年升高6.3 m,温度平均每年下降0.002 K,压强平均每年下降0.15 hPa。

The spatial-temporal characteristics of the tropopause height in land area of China is studied for the first time by the refractivity covariance transformation method using the Constellation Observing System for Meteorology, Ionosphere and Climate(COSMIC) mission from 2007 to 2014. Results show that the tropopause height in land area of China varies with latitudes, exhibiting a "south high and north low" pattern, while the temperature and pressure distribution at the troposphere are opposite to the height distribution. Meanwhile, the tropopause height in land area of China shows strong seasonal correlation. Most land area of China has the higher tropopause in summer and the lower tropopause in winter, but the opposite in low latitudes(16°N^26°N). Between 30°N and 40°N, the variation of the season in the subtropical zone is more significant, and the strong concentration of isolines can be found. By using median of pairwise slopes regression method to analyze the annual average value of the tropopause height during 2007 to 2014, it is found that the tropopause height increases 6.3 m/a, the temperature decreases 0.002 K/a and the pressure decreases 0.15 hPa/a.