Deep Eye Clouds in Tropical Cyclone Trami (2018) during T-PARCII Dropsonde Observations
Deep Eye Clouds in Tropical Cyclone Trami (2018) during T-PARCII Dropsonde Observations
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T-PARCII 下投探空仪观测期间热带气旋 Trami (2018) 中的深眼云
DOI：
10.1175/jas-d-21-0192.1
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发表时间：
2022
影响因子：
3.1
通讯作者：
Wu Chun-Chieh
中科院分区：
文献类型：
--
作者：
Hirano Soichiro;Ito Kosuke;Yamada Hiroyuki;Tsujino Satoki;Tsuboki Kazuhisa;Wu Chun-Chieh
利用水滴探空仪资料和大气-海洋耦合模式的模拟结果，研究了热带气旋(TC)Trami(2018)眼内零星的短时对流云的形成。根据卫星资料，对流云的顶部高度在平均海平面以上9公里以上，比典型的中心云(2-3公里)要高得多。这些云团位于距TC中心10-30公里的地方。因此，这些对流云在本研究中被称为深眼云(DECS)。下落探空仪的数据显示，在DECS形成期间，眼睛区域的相对湿度增加。耦合模式模拟了眼区对流层中层以下的短时对流云。热力学条件的研究表明，在DECS形成期间，一个减弱的低层暖核和与之相关的有利于眼区对流的条件。DECS是在眼壁内对流加热减弱和向外移位后形成的。为了阐明眼壁对流加热的变化对DECS形成的影响，我们用Sawyer-Eliassen方程计算了由眼壁对流加热引起的次级环流和相关的绝热增温。在眼区，随着DECS的形成，观测到下沉的减弱和与之相关的垂直位温平流。这表明眼壁内对流加热的减弱和向外移位为DECS的零星形成创造了有利条件。
The sporadic formation of short-lived convective clouds in the eye of Tropical Cyclone (TC) Trami (2018) is investigated using dropsonde data and simulation results from a coupled atmosphere–ocean model. According to the satellite data, top height of the convective clouds exceeds 9 km above mean sea level, considerably taller than that of typical hub clouds (2–3 km). These clouds are located 10–30 km away from the TC center. Hence, these convective clouds are called deep eye clouds (DECs) in this study. The dropsonde data reveal an increase in relative humidity in the eye region during the formation of DECs. Short-lived convective clouds are simulated up to the middle troposphere in the eye region in the coupled model. Investigation of thermodynamic conditions shows a weakened low-level warm core and associated favorable conditions for convection in the eye region during the formation of DECs. DECs are formed after the weakening and outward displacement of convective heating within the eyewall. To elucidate the influence of the changes in convective heating within the eyewall on the formation of DECs, we calculate secondary circulation and associated adiabatic warming induced by convective heating within the eyewall using the Sawyer–Eliassen equation. In the eye region, weakening of subsidence and associated vertical potential temperature advection is observed as DECs are formed. This suggests that the weakening and outward displacement of convective heating within the eyewall create favorable conditions for the sporadic formation of DECs.