Analyses of Shallow Convection over the Amazon Coastal Region Using Satellite Images, Data Observations and Modeling

Luciana Bassi Marinho Pires,Luciana Rossato,João Teixeira,Kay Suselj

doi:10.1590/0102-7786332009

Abstract

Abstract The Belem region of the state of Para, which is located in northern of Brazil and part of the Amazon biome is characterized by high temperatures, strong convection, unstable air conditions and high humidity favoring the formation of convective clouds. Shallow convection and deep convection are among the main components of the local energy balance. Typically a deep convection over the continents is preceded by a shallow convection. An analysis of the performance of the Jet Propulsion Laboratory / National Aeronautics and Space Administration (JPL/NASA) model of shallow convection parameterization in a framework of the single column model (SCM), in relation to the cluster of cumulus clouds formed in the coastal region of the Amazon forest due to squall lines, is provided. To achieve this purpose enhanced satellite images and infrared images from channels 2 and 4 from the GOES-12 satellite, and data obtained by the “Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GPM (GlobAl Precipitation Measurement)” - CHUVA - campaign, during the month of June of 2011, were used. During that period, clusters of cumulus clouds penetrated the interior of the Amazon, causing heavy rains. Results demonstrated that the parameterizations performed well in the case where only a core of clouds was observed, such as at 18:00h on 14 June. This period of the day also presents the smallest bias and root mean square error (rmse) values for the relative humidity. For the potential temperature the smallest value of bias is at 12:00h on June 7th (0.18 K), the largest one is on June 11th (-2.32 K) and the rmse ranges from 0.59 to 2.99 K.

Highlights

The largest forest of the world, the Amazon, presents an interesting and very complex system-mixing forests, various topographies, sites of deforestation, cities, and regions close and far from the coast, which influence the climatology of the region (Garstang et al, 1990 and 1994; Greco et al, 1990 and 1994; Cohen et al, 1995; Fu et al, 1999; Petersen et al, 2002 and 2006). Greco et al (1990) classify the Amazon convection in three systems: Coast Occurring Systems (COS), Basin Occurring Systems (BOS) and Locally Occurring Systems (LOS)
The Belem region in Brazil is characterized by high temperatures, strong convection, unstable atmospheric conditions and high humidity, favoring the formation of convective clouds
The strong convection, instability and high humidity favor the formation of convective clouds, giving rise to a high incidence of rainfall in the form of showers, mainly in the afternoon, a situation characteristic of a type of continental rain system (Nechet, 1997), found by Negri et al (2000) whose article about the 10 years of climatology of Amazonian rainfall shows a persistent local rainfall maximum at 18:00 LST on the northern coast of South America, which due to interactions between sea-breeze and the squall line formation moved inland at 21:00 LST

Summary

Introduction

The largest forest of the world, the Amazon, presents an interesting and very complex system-mixing forests, various topographies, sites of deforestation, cities, and regions close and far from the coast, which influence the climatology of the region (Garstang et al, 1990 and 1994; Greco et al, 1990 and 1994; Cohen et al, 1995; Fu et al, 1999; Petersen et al, 2002 and 2006). Greco et al (1990) classify the Amazon convection in three systems: Coast Occurring Systems (COS), Basin Occurring Systems (BOS) and Locally Occurring Systems (LOS) (see Adams et al, 2009 for a review). The Belem region in Brazil is characterized by high temperatures, strong convection, unstable atmospheric conditions and high humidity, favoring the formation of convective clouds. The strong convection, instability and high humidity favor the formation of convective clouds, giving rise to a high incidence of rainfall in the form of showers, mainly in the afternoon, a situation characteristic of a type of continental rain system (Nechet, 1997), found by Negri et al (2000) whose article about the 10 years of climatology of Amazonian rainfall shows a persistent local rainfall maximum at 18:00 LST on the northern coast of South America, which due to interactions between sea-breeze and the squall line formation moved inland at 21:00 LST. Shallow convection (no precipitation, following the traditional division of convective parameterization) and deep convection (precipitation) are among the main components of the local energy balance (Adams et al, 2009; Tavares and Mota, 2012)

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Conclusion