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26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.

题目一：On the use of trace gas measurements to diagnose convective transport pathways in the tropical western Pacific

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题目二：On the Level of Neutral Buoyancy and Deep Convective Outflow

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时间：2018年6月13日（周三）下午15:00

地点：珠海校区行政楼517报告厅

主持人：王东海 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：188 238 778，密码：888888

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报告简介：

Convective transport pathways from the boundary layer (BL) to the upper troposphere (UT) are investigated using 65 trace gases with a wide range of lifetime (LT) measured in the tropical western Pacific (TWP) during a recent airborne campaign. It was found that the UT-BL ratio of tracer concentration follows a compact relationship with tracer LT. Similar relationship is also seen in WACCM and CAMchem simulations. To explain this relationship, we assume the sampled UT air mass is a mixture of air parcels transported from the BL via a large number of pathways (see the attached drawing) with different transit times and define a “transit time spectrum” to describe their relative contributions. Since tracers with different LTs are sensitive to different parts of the spectrum, we are able to use a suite of tracers, with the help of a simple model and statistical data fitting, to piece together the whole spectrum. Results show that although the “transit time spectrum” is broad, the mode is only 3.8 days, suggesting that most of the UT air mass in the TWP warm pool comes through rapid transport paths. Transport with longer time scale makes smaller contributions. Caveats and implications of the study will be discussed. Finally, we will discuss the utility of the new diagnostics (e.g., UT-BL ratio of tracer concentration and “transit time spectrum”) for evaluating global models in their representation and parameterization of convective transport.