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

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. Here, 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 mass-weighted 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 characteristicsmore » 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 during 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.« less
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  1. National Inst. for Space Research (INPE), Sao Jose dos Campos (Brazil)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Univ. of Sao Paulo (Brazil). Inst. of Astronomy, Geophysics, and Atmospheric Sciences
  4. Max Planck Inst. for Chemistry, Mainz (Germany); Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography
  5. Univ. of Sao Paulo (Brazil). Inst. of Physics
  6. Max Planck Inst. for Chemistry, Mainz (Germany)
  7. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  8. Dept. of Aerospace Science and Technology, Sao Jose dos Campos (Brazil)
  9. Harvard Univ., Cambridge, MA (United States)
  10. Hebrew Univ. of Jerusalem (Israel)
  11. Amazon Protection System (SIPAM), Manaus (Brazil)
  12. Texas A & M Univ., College Station, TX (United States)
  13. Snow College, Richfield, UT (United States)
  14. Leipzig Univ., Leipzig (Germany). Leipzig Inst. for Meteorology
Publication Date:
Report Number(s):
Journal ID: ISSN 1680-7324
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 18; Journal Issue: 9; Journal ID: ISSN 1680-7324
European Geosciences Union
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
OSTI Identifier: