Title: Mesoscale convective systems over the Amazon basin: The GoAmazon2014/5 program

Abstract

The Green Ocean Amazon (GoAmazon2014/5) scientific program focused on the influence of aerosols and surface fluxes on tropical cloud formation. This major research effort gathered high-quality environmental data over the central Amazon basin during 2014 and 2015. The present work is a contribution to the GoAmazon2014/5 investigations with an emphasis on the behaviour of the most important mechanism of precipitation over the tropics: mesoscale convective systems (MCSs). To provide a background, MCSs' tracks obtained from infrared satellite images over the entire Amazon basin in 2014–2015 are compared with climatological values. We report the number of MCSs and precipitation in the basin is about 50% lower than compared to the climatology for 2000–2013. We argue that the below average occurrence of MCSs during the GoAmazon2014/5 program can be explained, at least in part, by the effects of positive anomalies in sea surface temperature over the equatorial Pacific Ocean, negative moisture transport toward the Amazon basin, and by the anticyclonic phase of the mode of interannual and intraseasonal variability over South America. Special attention is given to the 99 MCSs that occurred over the GoAmazon2014/5 site. The impact of MCSs on the meteorological variables over the GoAmazon2014/5 sites is examined, and themore » contribution of MCSs to rainfall over that region is estimated to be about 70% of the total. Finally, the synoptic and thermodynamic conditions related to the MCSs' genesis and dissipation are discussed. It is suggested that in days with reduced MCS genesis over the GoAmazon2014/5 region, the ventilation over the continent by easterly winds from the relative cold South Atlantic Ocean favours convection at locations near the ocean as compared to those inland.« less

Authors:

Rehbein, Amanda  ^[1];

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Ambrizzi, Tercio ^[1]; Mechoso, Carlos Roberto ^[2]; Espinosa, Sergio Alejandro Ibarra ^[1]; Myers, Timothy Albert ^[3]

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+ Show Author Affiliations

1. Univ. of Sao Paulo (Brazil). Inst. of Astronomy, Geophysics and Atmospheric Sciences
2. Univ. of California, Los Angeles, CA (United States)
3. Univ. of California, Los Angeles, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Cloud Processes Research Group

Publication Date:

Tue May 28 00:00:00 EDT 2019

Research Org.:

Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); Coordination for the Improvement of Higher Education Personnel (CAPES) (Brazil); São Paulo Research Foundation (FAPESP) (Brazil); Brazilian National Council for Scientific and Technological Development (CNPq)

OSTI Identifier:

1599555

Alternate Identifier(s):

OSTI ID: 1559352

Report Number(s):

LLNL-JRNL-769922
Journal ID: ISSN 0899-8418; 961109

Grant/Contract Number:  

AC52-07NA27344; 1547912; 16/2014; 2014/50848-9; 465501/2014-1; 2016/10557-0

Resource Type:

Accepted Manuscript

Journal Name:

International Journal of Climatology

Additional Journal Information:

Journal Volume: 39; Journal Issue: 15; Journal ID: ISSN 0899-8418

Publisher:

Royal Meteorological Society

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Amazon basin; GoAmazon2014/5; mesoscale convective systems