Study on the dehydration processes in the tropical tropopause layer by measurements of minor constituents and numerical modeling

本研究的目的是为了更好地了解热带对流层顶层的脱水过程，并通过使用西部热带太平洋的霜点湿度计进行无线电探空观测，监测热带平流层下层的水汽趋势。本项目的独特之处在于水汽“匹配”的协同观测策略，即运行一个站点网络，捕捉两次或两次以上相同的空气包裹，以量化观测到的特定空气的脱水量。从累积资料中得到的主要发现是：观测气包的含水量与相应气包轨迹上的饱和水混合比之间存在密切的关系，反映了气象站位置、等熵水平、季节和enso状态等气象条件。探空仪剖面的具体特征，例如相对湿度的跳跃，可以在单个探空基础上作为空气包起源的差异进行追踪。这一事实为我们确定“匹配”对提供了一些信心，尽管这种尝试存在困难。将水剖面与由激光雷达观测到的卷云分布进行比较，在空气的凝结和过饱和方面显示出有趣的结果。其中一些结果已在国际会议上提出并发表在文献中。不幸的是，由于美国的预算问题，与TC4的合作观测没有进行。然而，我们的数据有助于验证卫星观测。最后值得一提的是，我们已经用莱曼α湿度计进行了一些试飞，并正在准备通过合并观测数据进行一些同化运行，以用于当前研究的未来扩展。

The purpose of the present study is to better understand the dehydrationprocesses in the TropicalTropopause Layer and to monitor the water vapor trend in the tropical lower stratosphere by conducting radiosonde observations using frostpoint hygrometers in the western for the water tropical Pacific. Uniqueness of this project lies in the coordinated observation strategy for the water vapor "match", that is, to operate a network of stations to catch the same air parcels twice or more toquantify the dehydrated amount for the specific air observed. The main findings so far obtained from the accumulated data are: There are close relationships between the water amount of the observed air parcel and the saturation water mixing ratio along the trajectories of the corresponding air parcel reflecting the meteorological conditions such as the location of the stations, isentropic levels, season and ENSOstatus. Specific features of the sonde profiles such as a jump in the relative humidity could be traced as a difference in the origin of the air parcel on an individual sounding basis. This fact provides us some confidence in identifying the "match" pairs in spite of the difficulties in such an attempt. Comparisons of the water profiles with cirrus distributions observed by lidars show interesting results on the condensation and super saturation for the air. Some of these results have been presented in international conferences and published in the literature. Unfortunately, the collaborative observations with TC4 did not take place due to the budget problem in US. However, our data have contributed to the validation of satellite observations. Finally it will be worth mentioning that we have conducted some test flights with Lyman alpha hygrometer and are preparing some assimilation runs by incorporating observed data for the future extension of the current study.