Abstract An attempt has been made to understand the effect of the cirrus clouds on the tropical tropopause thermal structure over a tropical station Gadanki (13.45oN, 79.2oE) using regular radiosonde observation at 12:00Z and CALIPSO measurements at the closest proximity to Gadanki during 2006–2013. As the CALIPSO and radiosonde observation timings are not simultaneous, we considered only those cases when cirrus clouds are appeared both during daytime and nighttime over Gadanki. In total 45 simultaneous cirrus clouds and temperature observations are found. Out of which 24 cases are found with cirrus clouds top within 1.0 km of cold point tropopause (CPT; called tropopause cirrus) and 16 cases are below 2.0 km of CPT. The tropopause cirrus is further classified into geometrically thin (thick) cirrus clouds based on its thickness less (greater) than 2.0 km. Out of them 9 and 15 cases are found as geometrically thin and thick cirrus, respectively. The temperature profiles for geometrically thin, thick and the cases with cirrus below the tropopause show different structure from the clear-sky temperature profile. The mean difference between temperature gradients of geometrically thin and thick cases with clear-sky shows a distinct peak near the tropopause which coincides with the peak of mean volume depolarization ratio indicating that tropopause cirrus modifies the tropopause structure. Finally, the relationship between various tropopause parameters with cirrus cloud top height is obtained. For the tropopause cirrus cases, CPT becomes warmer by ∼1.2 K, COT rises by 0.8 km, TTL thickness (temperature) decreases (increases) by ∼0.9 km (2.2 K) with increase in the cloud optical thickness and cloud radiative forcing. However, TTL becomes relatively colder and thicker for the cirrus clouds occurring below the tropopause.

中文翻译：

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卷云对热带对流层顶热结构影响的定性观测

摘要 已尝试使用 12:00Z 的常规无线电探空仪观测和最接近 Gadanki 的 CALIPSO 测量来了解卷云对热带站 Gadanki（13.45oN，79.2oE）上热带对流层顶热结构的影响。 2006-2013 年。由于 CALIPSO 和无线电探空仪观测时间不是同时发生的，我们只考虑了白天和夜间在 Gadanki 上空都出现卷云的情况。总共发现了 45 个同时进行的卷云和温度观测。其中24例在冷点对流层顶（CPT；称为对流层顶卷云）1.0km范围内卷云顶部，16例在CPT2.0km以下。根据其厚度小于（大于）2.0 公里，对流层顶卷云进一步分为几何上薄（厚）的卷云。其中 9 例和 15 例分别为几何薄卷云和厚卷云。几何上薄、厚和对流层顶以下有卷云的情况的温度剖面显示出与晴空温度剖面不同的结构。晴空下几何薄层和厚层的温度梯度平均差在对流层顶附近有一个明显的峰值，与平均体积去极化比的峰值重合，表明对流层顶卷云改变了对流层顶结构。最后得到各种对流层顶参数与卷云顶高的关系。对于对流层顶卷云的情况，CPT 变暖约 1.2 K，COT 增加 0.8 公里，TTL 厚度（温度）随着云光学厚度和云辐射强迫的增加而减少（增加）~0.9 公里（2.2 K）。然而，对于出现在对流层顶之下的卷云，TTL 变得相对更冷和更厚。