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Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDEThe Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident satellite sensor (TOMS, MODIS, MISR) measurements. AATS-6 AOD data acquired during numerous aircraft ascents and descents through the MBL and the SAL should permit atmospheric column closure analyses with respect to aerosol optical depth, extinction, and size distribution by comparison with coincident aircraft-based in-situ particle size distribution measurements and ground-based (Cabras Island, Puerto Rico) micropulse lidar aerosol backscatter measurements. The aerosol information derived from the column closure analyses can be used subsequently to calculate radiative flux changes, which can then be compared with coincident spectral flux measurements taken from aboard the aircraft with a solar spectral flux radiometer.
Document ID
20010092168
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Livingston, John M.
(NASA Ames Research Center Moffett Field, CA United States)
Redemann, Jens
(NASA Ames Research Center Moffett Field, CA United States)
Russell, Philip
(NASA Ames Research Center Moffett Field, CA United States)
Schmid, Beat
(NASA Ames Research Center Moffett Field, CA United States)
Reid, Jeff
(NASA Ames Research Center Moffett Field, CA United States)
Pilewskie, Peter
(NASA Ames Research Center Moffett Field, CA United States)
Hipskind, R. Stephen
Date Acquired
August 20, 2013
Publication Date
January 12, 2000
Subject Category
Environment Pollution
Meeting Information
Meeting: American Geophysical Union 2000 Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 15, 2000
End Date: December 19, 2000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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