Overview: Precipitation characteristics and sensitivities to environmental conditions during GoAmazon2014/5 and ACRIDICON-CHUVA

Abstract

Abstract. This study provides an overview of precipitation processes and their sensitivities to environmental conditions in the Central Amazon Basin near Manaus during the GoAmazon2014/5 and ACRIDICON-CHUVA experiments. This study takes advantage of the numerous measurement platforms and instrument systems operating during both campaigns to sample cloud structure and environmental conditions during 2014 and 2015; the rainfall variability among seasons, aerosol loading, land surface type, and topography has been carefully characterized using these data. Differences between the wet and dry seasons were examined from a variety of perspectives. The rainfall rates distribution, total amount of rainfall, and raindrop size distribution (the massweighted mean diameter) were quantified over both seasons.The dry season generally exhibited higher rainfall rates than the wet season and included more intense rainfall periods. However, the cumulative rainfall during the wet season was 4 times greater than that during the total dry season rainfall, as shown in the total rainfall accumulation data. The typical size and life cycle of Amazon cloud clusters (observed by satellite) and rain cells (observed by radar) were examined, as were differences in these systems between the seasons. Moreover, monthly mean thermodynamic and dynamic variables were analysed using radiosondes to elucidate the differences in rainfall characteristics during the wet and dry seasons. The sensitivity of rainfall to atmospheric aerosol loading was discussed with regard to mass-weighted mean diameter and rain rate. This topic was evaluated only durPublished by Copernicus Publications on behalf of the European Geosciences Union. L. A. T. Machado et al.: Overview: Precipitation characteristics and sensitivities to environmental conditionsing the wet season due to the insignificant statistics of rainfall events for different aerosol loading ranges and the low frequency of precipitation events during the dry season. The impacts of aerosols on cloud droplet diameter varied based on droplet size. For the wet season, we observed no dependence between land surface type and rain rate. However, during the dry season, urban areas exhibited the largest rainfall rate tail distribution, and deforested regions exhibited the lowest mean rainfall rate. Airplane measurements were taken to characterize and contrast cloud microphysical properties and processes over forested and deforested regions. Vertical motion was not correlated with cloud droplet sizes, but cloud droplet concentration correlated linearly with vertical motion. Clouds over forested areas contained larger droplets than clouds over pastures at all altitudes. Finally, the connections between topography and rain rate were evaluated, with higher rainfall rates identified at higher elevations during the dry season.

Erosion of the nocturnal boundary layer in the central Amazon during the dry season

“…The GoAmazon 2014/5 project collected data on the vertical structure of the PBL, to characterize the convection, its development and evolution using a variety of instruments to measure the behavior of surface and atmospheric variables that are important for understanding biosphere-atmosphere interactions (Marengo et al 2017;Machado et al 2018).…”

Land cover and its transformation in the backward trajectory footprint region of the Amazon Tall Tower Observatory

“…Based on the entire set of 74 496 3 d BTs (1 January 2008-30 June 2016) we conducted a k means cluster analysis (CA, with Euclidian distances) -the most commonly used partitioning clustering approach -which provides a (nonsupervised) classification of the trajectories' spatiotemporal variability (MacQueen, 1967;Kassambara, 2017). The 3 d BTs were selected as input data for the clustering to retrieve the BT's spatiotemporal variability over the South American continent and, particularly, over the NE Amazon Basin.…”

Aircraft-based observations of isoprene-epoxydiol-derived secondary organic aerosol (IEPOX-SOA) in the tropical upper troposphere over the Amazon region

“…In the laboratory, the acidic conditions are often realized by using sulfate seed particles (e.g., Surratt et al, 2010;Darer et al, 2011;Lin et al, 2012Lin et al, , 2013. Also in field studies a correlation between IEPOX-SOA and sulfate aerosol was proposed (e.g., Lin et al, 2013;Allan et al, 2014;Hu et al, 2015;Xu et al, 2015;Marais et al, 2016;de Sá et al, 2017). Figure 8 shows the scatter plot of IEPOX-SOA against nitrate (panel a) and sulfate (panel b) mass concentrations for LT and UT, respectively.…”