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TG-03 Abstract

Characterization of Aerosol Optical Properties and Column Water Vapor for LBA-Ecology

Paulo Artaxo — USP - Universidade de Sao Paulo (SA-PI)
Brent Norman Holben — NASA/GSFC (US-PI)
Alberto W Setzer — CPTEC - Centro de Previsão do Tempo e Estudos Climáticos (INPE) (SA-PI)

Objectives





We

are characterizing aerosol optical properties and column water vapor during the

LBA study. Many LBA researchers will be utilizing satellite imagery for

large-scale analysis and therefore will require aerosol optical thickness and

precipitable water amounts for accurate atmospheric correction algorithms. A

year-round network of six ground-based automatic sunphotometers will be

established to emphasize the ecological and remote sensing effects of aerosols.

These instruments will be collocated with LBA-designated tower sites when

feasible. Three additional instruments were purchased by Brazilian researchers

and deployed in a wider distribution near the boundaries of the Amazon region.

This study will build on NASA's existing global AERONET atmospheric

characterization system and the University of São Paulo in-situ aerosol-sampling program. In this manner, comprehensive

climatologies of aerosol and water vapor can be developed that encompass both

burning and non-burning seasons for the entire Amazon basin. We intend to use

this opportunity to investigate the long-term effects of biomass burning on the

vegetation and atmosphere of the Amazon basin and the nature of the atmospheric

aerosol observed on a year-round basis.





Site Instrumentation





Each

LBA site was instrumented with a Cimel automatic sun/sky scanning spectral

radiometer (direct sun and sky radiance measurements), UVB sensor (0.28-0.32

(m), PAR sensor (0.4-0.7 (m), broadband pyranometer (0.28-2.8 m), and satellite

transmission equipment. Automated Cimel sunphotometers make direct sun

measurements at 8 wavelengths approximately every 15 minutes from which aerosol

optical thickness (AOT) at 7 wavelengths, and precipitable water will be

derived. Sky radiance almucantar measurements are also performed automatically

which are inverted to yield aerosol size distributions and phase functions.





Seasonal Monitoring





We are using this data set to investigate

the long-term effects of biomass burning on the vegetation and atmosphere of the

Amazon basin and the nature of the atmospheric aerosol observed on a year-round

basis. The broadband radiometers will provide irradiance data in wavebands

significant to vegetative production, and allow characterization of aerosol

absorption parameters relevant to remote sensing and climate models. We have

also characterized the direct radiative forcing at the surface for all sites

having the full suite of instrumentation.



Field Campaigns





During

intensive field campaigns, one site will also feature an Optronics

spectroradiometer (0.3-0.8 (
mm)

to measure spectral irradiance

and a Yankee MFRSR spectral radiometer (diffuse flux component) to further

radiative modeling efforts, and a number of handheld sunphotometers will be

deployed to better characterize the spatial variability of the atmospheric

aerosol. One field campaign is planned next year and will include measurements

during the pre-burning, burning and rainy seasons over the next 3 years.





Training and Education





Funds

were used for a Brazilian post doc from the University of São Paulo to do field

work and later, analysis at NASA/GSFC. The focus of the research will be surface

sampling of particulates with an emphasis on modeling of aerosol transport and

their chemical analysis (P, S, K and others) and dynamics, including dry

deposition mechanisms. Local site managers were taught to set up and maintain

instrument suites at each deployment site.



The

region is already familiar to the authors who operated a network of

sunphotometers successfully in the Amazon from 1993-1995, including the SCAR-B

campaign. Over this period, sites were developed efficiently in the states of

Rondônia, Mato Grosso, Tocantins, and others. Brazilian research aircraft will

be available at no expense during some field campaigns and will allow us to

operate a handheld sun photometer to assess the vertical distribution of

aerosol.





Sites





Our

permanent sites are Balbina, Abraços Hill, Rio Branco, Alta Floresta, Cuiabá,

Belterra and Belém.  A reference

site was established in São Paulo.  Solar

flux sensors are at all sites except Belém and Cuiabá. 







Activities





All

planned instruments have been deployed.  A

Dry-to-Wet transition season field campaign is planned for ‘02, which will

complement field campaigns from previous years. 



updated July 20, 2001



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