WCR: Upper Tropospheric Water Vapor over the Tropical Atlantic Ocean: Climatology, Variability, and Response to Deep Convection

在这个项目中，PI将分析和诊断热带大西洋上空对流层上层的湿度。自1994年9月以来，空中客车在役飞机臭氧和水蒸气测量项目的相对湿度和比湿度数据已经存在了10年。在热带大西洋上空深对流的主要流出层内的高度上，对从中欧到南美洲各地点的频繁飞行进行了测量，大多数是每周两次。这些数据几乎连续10年以上，将用于分析大西洋热带辐合带和邻近亚热带上空的热带对流层上层水汽。将特别注意在时间尺度上湿度变化的主要模式，从不到一周到年际和更长时间，长达10年。飞行水平的水分通量，使用共同测量的风速，将被计算，并与湿度信息一起，与再分析产品进行比较。对流层上部湿度的时空变化也与下垫面海表温度的时空变化有关。将进行诊断性研究，以检验关于热带大西洋上空对流层上层湿度的具体假设，并将使用臭氧测量值来推断水蒸气的来源，臭氧是对流输送时间尺度上的一种准保守示踪物。具体而言，将检验以下假设：在赤道槽区上空观测到的对流层上层湿度的高值与深对流引起的局部垂直输送直接相关，在亚热带大西洋上空的水汽分布主要受大尺度垂直运动控制，热带大西洋上空对流层上部湿度的观测到的季节内变化与马登-朱利安振荡直接相关。一名博士后研究助理将参与这项研究。

In this project the PI will analyze and diagnose upper-tropospheric humidity over the tropical Atlantic Ocean. Relative and specific humidity data from the Measurement of Ozone and Water Vapour by Airbus In-Service Aircraft project exist for 10 years since September 1994. Measurements have been made on frequent flights, mostly twice weekly, from Central Europe to locations in South America at levels within the dominant outflow layer of deep convection over the tropical Atlantic Ocean. The data, nearly continuous over 10 years, will be used for the analysis of tropical upper tropospheric water vapor over the Atlantic Intertropical Convergence Zone and the adjacent subtropics. Specific attention will be given to the dominant modes of variability of humidity on time scales varying from less than a week to inter-annual and beyond, up to 10 years. Flight level moisture fluxes, using co-measured wind velocities, will be computed and, together with the humidity information, compared with reanalysis products. The temporal and spatial variability of upper-tropospheric humidity will also be related to that of the underlying sea surface temperature. Diagnostic studies will be undertaken to test specific hypotheses concerning upper tropospheric humidity over the tropical Atlantic and measurements of ozone, a quasi-conservative tracer on the time scale of convective transport, will be used to deduce sources of water vapor. Specifically, the following hypotheses will be tested: that high values of observed upper-tropospheric humidity over the equatorial trough zone are directly related to local vertical transport by deep convection, that the water vapor distributions over the subtropical Atlantic are predominantly controlled by large-scale vertical motion, and that the observed intra-seasonal variability in the upper-tropospheric humidity over the tropical Atlantic is directly linked to the Madden-Julian Oscillation. A post-doctoral research associate will be involved in the research.