Premium
Cloudiness over the Amazon rainforest: Meteorology and thermodynamics
Author(s) -
Collow Allison B. Marquardt,
Miller Mark A.,
Trabachino Lynne C.
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd024848
Subject(s) - amazon rainforest , climatology , environmental science , cloud cover , atmospheric sciences , water vapor , dry season , subsidence , advection , precipitable water , precipitation , water cycle , meteorology , geography , geology , cloud computing , physics , structural basin , thermodynamics , ecology , paleontology , cartography , computer science , biology , operating system
Comprehensive meteorological observations collected during GOAmazon2014/15 using the Atmospheric Radiation Measurement Mobile Facility no. 1 and assimilated observations from the Modern‐Era Retrospective Analysis for Research and Applications, Version 2 are used to document the seasonal cycle of cloudiness, thermodynamics, and precipitation above the Amazon rainforest. The reversal of synoptic‐scale vertical motions modulates the transition between the wet and dry seasons. Ascending moist air during the wet season originates near the surface of the Atlantic Ocean and is advected into the Amazon rainforest, where it experiences convergence and, ultimately, precipitates. The dry season is characterized by weaker winds and synoptic‐scale subsidence with little or no moisture convergence accompanying moisture advection. This combination results in the drying of the midtroposphere during June through October as indicated by a decrease in liquid water path, integrated water, and the vertical profile of water vapor mixing ratio. The vertical profile of cloud fraction exhibits a relatively consistent decline in cloud fraction from the lifting condensation level (LCL) to the freezing level where a minimum is observed, unlike many other tropical regions. Coefficients of determination between the LCL and cloud fractional coverage suggest a relatively robust relationship between the LCL and cloudiness beneath 5 km during the dry season ( R 2 = 0.42) but a weak relationship during the wet season (0.12).