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Variability of Marine Aerosol Fine-Mode Fraction and Estimates of Anthropogenic Aerosol Component Over Cloud-Free Oceans from the Moderate Resolution Imaging Spectroradiometer (MODIS)In this study, we examine seasonal and geographical variability of marine aerosol fine-mode fraction (f(sub m)) and its impacts on deriving the anthropogenic component of aerosol optical depth (tau(sub a)) and direct radiative forcing from multispectral satellite measurements. A proxy of f(sub m), empirically derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) Collection 5 data, shows large seasonal and geographical variations that are consistent with the Goddard Chemistry Aerosol Radiation Transport (GOCART) and Global Modeling Initiative (GMI) model simulations. The so-derived seasonally and spatially varying f(sub m) is then implemented into a method of estimating tau(sub a) and direct radiative forcing from the MODIS measurements. It is found that the use of a constant value for fm as in previous studies would have overestimated Ta by about 20% over global ocean, with the overestimation up to 45% in some regions and seasons. The 7-year (2001-2007) global ocean average tau(sub a) is 0.035, with yearly average ranging from 0.031 to 0.039. Future improvement in measurements is needed to better separate anthropogenic aerosol from natural ones and to narrow down the wide range of aerosol direct radiative forcing.
Document ID
20100034943
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Yu, Hongbin
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Chin, Mian
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Remer, Lorraine A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kleidman, Richard G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Bellouin, Nicolas
(Met Office (Meteorological Office) Devon, United Kingdom)
Bian, Huisheng
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Diehl, Thomas
(Maryland Univ. Baltimore County Baltimore, MD, United States)
Date Acquired
August 25, 2013
Publication Date
May 29, 2009
Publication Information
Publication: Journal of Geophysical Research
Volume: 114
Subject Category
Meteorology And Climatology
Distribution Limits
Public
Copyright
Other

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