Cloud characteristics, thermodynamic controls and radiative impacts during the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) experiment

Abstract

Abstract. Routine cloud, precipitation and thermodynamic observations collected by the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) and Aerial Facility (AAF) during the 2-year US Department of Energy (DOE) ARM Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign are summarized. These observations quantify the diurnal to large-scale thermodynamic regime controls on the clouds and precipitation over the undersampled, climatically important Amazon basin region. The extended ground deployment of cloud-profiling instrumentation enabled a unique look at multiple cloud regimes at high temporal and vertical resolution. This longerterm ground deployment, coupled with two short-term aircraft intensive observing periods, allowed new opportunities to better characterize cloud and thermodynamic observational constraints as well as cloud radiative impacts for modeling efforts within typical Amazon "wet" and "dry" seasons.

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

“…For the Central Amazonas region, July, August, and September are typically the driest months. Convection in Amazonas is more intense during the dry to wet transition season, during which thunderstorms exhibit more lightning activity (Albrecht et al, 2011) and are more sensitive to aerosol loading and topography (Gonçalves et al, 2015). The transition from the dry to wet season is influenced by complex interactions between smoke-derived aerosols and deep convective clouds (Albrecht et al, 2011).…”

“…For instance, the effect of aerosol concentrations on cloud droplets in shallow convective clouds, where aerosols generally reduce the size and increase the concentration of a given liquid water content, is well known , among several other studies). However, if a polluted cloud transitions from shallow to deep convection, aerosols can invigorate clouds (Rosenfeld, 2008;Koren et al, 2012;Gonçalves et al, 2015). Giangrande et al (2017) present the G1 airplane cloud particle distribution measurements taken during GoAmazon2014/5 and show the predominance of larger cloud droplets in warm clouds during the wet season.…”

“…Burleyson et al (2016) have discussed the diurnal cycle and spatial variability of deep convection among the different GoAmazon sites. Giangrande et al (2017) have also presented an overview of cloud, thermodynamics, and radiation interactions.…”

“…During the dry season, only regions with strong forcing can produce convective clouds that use the higher CAPE and shear available to produce organized convection. Gonçalves et al (2015) show that increased RRs (radar reflectivity values larger than 35 dBZ) during the dry season mainly occur over higher elevations in Amazonas (Sect. 3.2.1).…”

“…In GoAmazon2014/5, the extensive rainfall dataset collected using the S-, X-, and W-band radars, airplanes, disdrometers and vertical-pointing radar, rain gauges, microwave radiometers, ceilometers, and lidar provides a comprehensive view of the main variables and characteristics of precipitation in the central Amazon. Giangrande et al (2017) present an overview of cloud aspects that primarily focuses on the diurnal cycle and its impact on the radiative and thermodynamic effects of clouds. This study presents an overview of the rainfall characteristics and sensitivities to vegetation, topography, and aerosol particles and evaluates the seasonal variability of these factors.…”