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Calculations of Solar Shortwave Heating Rates due to Black Carbon and Ozone Absorption Using in Situ MeasurementsResults for the solar heating rates in ambient air due to absorption by black-carbon (BC) containing particles and ozone are presented as calculated from airborne observations made in the tropical tropopause layer (TTL) in January-February 2006. The method uses airborne in situ observations of BC particles, ozone and actinic flux. Total BC mass is obtained along the flight track by summing the masses of individually detected BC particles in the range 90 to 600-nm volume-equivalent diameter, which includes most of the BC mass. Ozone mixing ratios and upwelling and partial downwelling solar actinic fluxes were measured concurrently with BC mass. Two estimates used for the BC wavelength-dependent absorption cross section yielded similar heating rates. For mean altitudes of 16.5, 17.5, and 18.5 km (0.5 km) in the tropics, average BC heating rates were near 0.0002 K/d. Observed BC coatings on individual particles approximately double derived BC heating rates. Ozone heating rates exceeded BC heating rates by approximately a factor of 100 on average and at least a factor of 4, suggesting that BC heating rates in this region are negligible in comparison.
Document ID
20110014382
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Gao, R. S.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Hall, S. R.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Swartz, W. H.
(Johns Hopkins Univ. Laurel, MD, United States)
Spackman, J. R.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Watts, L. A.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Fahey, D. W.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Aikin, K. C.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Shetter, R. E.
(National Oceanic and Atmospheric Administration Boulder, CO, United States)
Bui, T. P.
(NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 25, 2013
Publication Date
July 17, 2008
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 113
ISSN: 0148-0227
Subject Category
Geophysics
Funding Number(s)
CONTRACT_GRANT: NNX07AL38A
Distribution Limits
Public
Copyright
Other

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