Aerosol optical depth retrievals in central Amazonia from a multi-filter rotating shadow-band radiometer calibrated on-site

Author(s)

Rosario, Nilton E. ^[1] ; Sauini, Thamara ^[1] ; Pauliquevis, Theotonio ^[1] ; Barbosa, Henrique M. J. ^[2] ; Yamasoe, Marcia A. ^[3] ; Barja, Boris ^{[2, 4]}

Affiliation

^[1] Univ Fed Sao Paulo, Dept Ciencias Ambientais, Rua Sao Nicolau 210, BR-09913030 Diadema, SP - Brazil

^[2] Univ Sao Paulo, Inst Fis, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508090 Sao Paulo, SP - Brazil

^[4] Univ Magallanes, Punta Arenas 01855, Region Magallan - Chile

• Document type: Journal article
• Source: Atmospheric Measurement Techniques; v. 12, n. 2, p. 921-934, FEB 11 2019.
• Web of Science Citations: 0

Abstract

Extraterrestrial spectral response calibration of a multi-filter rotating shadow band radiometer (MFRSR) under pristine Amazonian Forest atmosphere conditions was performed using the Langley plot method. The MFRSR is installed in central Amazonia as part of a long-term monitoring site, which was used in the context of the GoAmazon2014/5 experiment. It has been operating continuously since 2011 without regular extraterrestrial calibration, preventing its application to accurate monitoring of aerosol particles. Once calibrated, the MFRSR measurements were applied to retrieve aerosol particle columnar optical properties, specifically aerosol optical depth (AOD(lambda)) and Angstrom exponent (AE), which were evaluated against retrievals from a collocated Cimel Sun photometer belonging to the AErosol RObotic NETwork (AERONET). Results obtained revealed that pristine Amazonian conditions are able to provide MFRSR extraterrestrial spectral response with relative uncertainty lower than 1.0% in visible channels. The worst estimate (air mass = 1) for absolute uncertainty in AOD(lambda) retrieval varied from approximate to 0.02 to approximate to 0.03, depending on the assumption regarding uncertainty for MFRSR direct normal irradiance measured at the surface. The obtained root mean square error (RMSE approximate to 0.025) from the evaluation of MFRSR retrievals against AERONET AOD(lambda) was, in general, lower than estimated MFRSR AOD(lambda) uncertainty, and close to the uncertainty of AERONET field Sun photometers (approximate to 0.02). (AU)

• FAPESP's process: 12/16100-1 - Cloud optical properties in the Amazon derived from LIDAR and Radiometer measurements
• Grantee: Henrique de Melo Jorge Barbosa
• Support type: Research Grants - Visiting Researcher Grant - International
• FAPESP's process: 13/05014-0 - GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia
• Grantee: Paulo Eduardo Artaxo Netto
• Support type: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 13/50510-5 - Brazil-USA collaborative research: modifications by anthropogenic pollution of the natural atmospheric chemistry and particle microphysics of the tropical rain forest during GoAmazon intensive operating periods
• Grantee: Henrique de Melo Jorge Barbosa
• Support type: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 17/17047-0 - Aerosol and clouds life cycles in Amazonia: biogenic emissions, biomass burning and impacts on ecosystem
• Grantee: Paulo Eduardo Artaxo Netto
• Support type: Research Program on Global Climate Change - Thematic Grants