广东省气候变化与自然灾害研究重点实验室和热带大气-海洋系统科学粤港澳联合实验室暨大气科学学院（2018年第25讲）

主讲人：罗正钊 教授

Department of Earth & Atmospheric Sciences

City University of New York, City College,?New York, NY, USA

题目：On the Level of Neutral Buoyancy and Deep Convective Outflow

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时间：2018年6月6日（周三）上午10:30

地点：南校园地环大楼C306室

主持人：陈桂兴?副教授

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本次学术报告将进行全程直播，
直播网址为：https://sysuatmos.webex.com.cn/
活动号：185 863 193，密码：888888

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报告简介：

Level of neutral buoyancy (LNB) is an important parameter for understanding deep convection because it sets the potential vertical extent for convective development. LNB can be estimated from the parcel theory using the ambient sounding without having to observe any actual convective cloud development. In reality, however, convection interacts with the environment in complicated ways; it will eventually find its own effective LNB and manifests it through detraining masses and developing cirrus anvils. In a series of recent papers, we investigated the relationship between the LNB and actual deep convective outflow using global observations from CloudSat. Due to dilution by entrainment, the actual deep convective outflow level is almost always lower than the LNB. The difference between the two can be interpreted as a proxy for entrainment rate. It was found that the entrainment rate as determined this way is larger over tropical ocean than tropical land. Analysis of radar reflectivity profiles further shows that land convection has wider and more intense cores than the oceanic counterpart. These findings lend important observational support to a long-standing assumption in convection models concerning the relationship between entrainment rate and convective intensity and core size. Finally, we show inter-annual variability of LNB and convective outflow, as well as the estimated entrainment rates and convective intensity/core size, during El Ni?o and La Ni?a periods.

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