Latitudinal and temporal distribution of aerosols and precipitable water vapor in the tropical Andes from AERONET, sounding, and MERRA-2 data

María Cazorla; David M Giles; Edgar Herrera; Luis Suárez; Rene Estevan; Marcos Andrade; Álvaro Bastidas

doi:10.1038/s41598-024-51247-9

Latitudinal and temporal distribution of aerosols and precipitable water vapor in the tropical Andes from AERONET, sounding, and MERRA-2 data

Sci Rep. 2024 Jan 9;14(1):897. doi: 10.1038/s41598-024-51247-9.

Authors

María Cazorla¹, David M Giles^{2

3}, Edgar Herrera⁴, Luis Suárez⁵, Rene Estevan⁵, Marcos Andrade^{6

7}, Álvaro Bastidas⁸

Affiliations

¹ Universidad San Francisco de Quito USFQ, Instituto de Investigaciones Atmosféricas, Quito, Ecuador. mcazorla@usfq.edu.ec.
² Science Systems and Applications, Inc. (SSAI), Lanham, MD, USA.
³ NASA Goddard Space Flight Center (GSFC), Greenbelt, MD, USA.
⁴ Universidad San Francisco de Quito USFQ, Instituto de Investigaciones Atmosféricas, Quito, Ecuador.
⁵ Instituto Geofísico del Perú, Huancayo, Peru.
⁶ Laboratorio de Física de la Atmósfera, Universidad Mayor de San Andrés, La Paz, Bolivia.
⁷ Department of Atmospheric and Oceanic Sciences, University of Maryland, College Park, MD, USA.
⁸ Universidad Nacional de Colombia Sede Medellin, Medellin, Colombia.

Abstract

The aerosol and precipitable water vapor (PW) distribution over the tropical Andes region is characterized using Aerosol Robotic Network (AERONET) observations at stations in Medellin (Colombia), Quito (Ecuador), Huancayo (Peru), and La Paz (Bolivia). AERONET aerosol optical depth (AOD) is interpreted using PM_2.5 data when available. Columnar water vapor derived from ozone soundings at Quito is used to compare against AERONET PW. MERRA-2 data are used to complement analyses. Urban pollution and biomass burning smoke (BBS) dominate the regional aerosol composition. AOD and PM_2.5 yearly cycles for coincident measurements correlate linearly at Medellin and Quito. The Andes cordillera's orientation and elevation funnel or block BBS transport into valleys or highlands during the two fire seasons that systematically impact South America. The February-March season north of Colombia and the Colombian-Venezuelan border directly impacts Medellin. Possibly, the March aerosol signal over Quito has a long-range transport component. At Huancayo and La Paz, AOD increases in September due to the influence of BBS in the Amazon. AERONET PW and sounding data correlate linearly but a dry bias with respect to soundings was identified in AERONET. PW and rainfall progressively decrease from north to south due to increasing altitude. This regional diagnosis is an underlying basis to evaluate future changes in aerosol and PW given prevailing conditions of rapidly changing atmospheric composition.