中文摘要：

使用2006年12月—2008年11月 COSMIC （constellation observing system for meteorology, ionosphere and climate）掩星湿廓线资料对第二对流层顶的全球分布特征进行统计,对比三个站点的无线电探空仪和COSMIC的对流层顶资料,研究结果表明：1）第二对流层顶的出现频率在副热带急流区较高,冬季在北半球为50%—70%,在南半球为20%—40%;2）赤道带的第二对流层顶出现频率约为20%—26%,与越赤道急流和对流层顶上的毛卷云有关;3）在副热带急流区,第一对流层顶的温度基本高于第二对流层顶;4）在热带,对流层顶厚度和第二对流层顶出现频率随纬度减小;热带以外,对流层顶厚度随纬度增加,在冬半球60？有最大值7—8 km;5）单站点对流层顶的日变化剧烈程度与COSMIC和探空仪的对流层顶高度偏差正相关.

英文摘要：

The global distribution of the second lapse-rate tropopause （LRT2） is investigated with the radio occultation measurements from the constellation observing system for meteorology, ionosphere and climate （COSMIC） covering December 2006–November 2008 Comparisons between COSMIC and radiosonde in terms of the tropopause are examined in three stations to check the difference. The research results are as follows. 1） In the winter, occurrence frequency for LRT2 in the northern hemisphere （NH） is of 50%–70%and in the southers hemisphere is of 20%–40%. 2） The second tropopause over the equatorial zone with 20%–26%occurrence seems to be related to the equatorial jet stream and subvisual cirrus above the first tropopause. 3） In the tropic, the difference in altitude and occurrence between the first and second tropopause decrease with latitude. In the extratropic zone, the difference increases with latitude and reaches a maximum of 7–8 km in the winter of the NH. 4） The second tropopause occurs frequently over the subtropical jet stream region, in which the first tropopause temperature is almost higher than the second one. 5） The more intense the single station daily variations of tropopause height, the bigger the difference between COSMIC and radiosonde is.