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

Author(s)

Rehbein, Amanda ^[1] ; Ambrizzi, Tercio ^[1] ; Mechoso, Carlos R. ^[2] ; Espinosa, I, Sergio A. ; Myers, Timothy A. ^{[2, 3]}

Affiliation

^[1] I, Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil

^[2] Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA - USA

^[3] Lawrence Livermore Natl Lab, Cloud Proc Res Grp, Livermore, CA 94550 - USA

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF CLIMATOLOGY; v. 39, n. 15, p. 5599-5618, DEC 2019.
• Web of Science Citations: 0

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. 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 the 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. (AU)

• FAPESP's process: 16/10557-0 - Mesoscale convective systems over the Amazon basin: present climate and future climate change scenarios
• Grantee: Amanda Rehbein
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 14/50848-9 - INCT 2014: INCT for Climate Change
• Grantee: Jose Antonio Marengo Orsini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants