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有10年的历史。从中欧到南美洲热带大西洋上的深层对流主要流出层水平的频繁飞行（基本上每周两次）已经进行了测量。这些数据几乎连续超过10年，将用于分析大西洋热带辐合带和邻近亚热带的热带对流层上层水汽。将特别注意湿度在时间尺度上的主要变率模式，时间尺度从不到一周到年际或更长，直至10年。将使用共同测量的风速计算飞行水平的湿度通量，并将其与湿度信息一起与再分析产品进行比较。对流层上层湿度的时空变化也与下垫海表温度的时空变化有关。将进行诊断性研究，以检验有关热带大西洋上空对流层上层湿度的具体假设，并将利用对对流输送时间尺度上的准保守示踪剂臭氧的测量来推断水汽的来源。具体来说，我们将测试以下假设：赤道槽区对流层上层湿度观测值偏高与局地深层对流垂直输送直接相关，副热带大西洋水汽分布主要受大尺度垂直运动控制，热带大西洋对流层上层湿度观测值的季节内变化与麦登-朱利安涛动直接相关。一名博士后研究员将参与研究。

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.