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AGU: Journal of Geophysical Research, Atmospheres

 

Index Terms

  • Atmospheric Composition and Structure: Aerosols and particles
  • Atmospheric Composition and Structure: Cloud physics and chemistry
  • Meteorology and Atmospheric Dynamics: Radiative processes
  • Meteorology and Atmospheric Dynamics: Remote sensing
Abstract
Cited By (49)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, 4699, 15 PP., 2003
doi:10.1029/2002JD003359

A study of the direct and indirect effects of aerosols using global satellite data sets of aerosol and cloud parameters

Miho Sekiguchi

Center for Climate System Research, University of Tokyo, Tokyo, Japan

Teruyuki Nakajima

Center for Climate System Research, University of Tokyo, Tokyo, Japan

Kentaroh Suzuki

Center for Climate System Research, University of Tokyo, Tokyo, Japan

Kazuaki Kawamoto

Research Institute for Humanity and Nature, Kyoto, Japan

Akiko Higurashi

National Institutes for Environmental Studies, Ibaraki, Japan

Daniel Rosenfeld

Hebrew University of Jerusalem, Jerusalem, Israel

Itaru Sano

Faculty of Science and Technology, Kinki University, Osaka, Japan

Sonoyo Mukai

Faculty of Science and Technology, Kinki University, Osaka, Japan

The present study investigated the correlations between aerosol and cloud parameters derived from satellite remote sensing for evaluating the radiative forcing of the aerosol indirect effect. The global statistics showed that the effective particle radius and the optical thickness of low clouds correlate well with the column number concentration of the aerosol particles, indicating an aerosol indirect effect. A correlation of the cloud fraction with the aerosol number was also seen, whereas we could not find a significant correlation of the cloud-top temperature with the column aerosol number. Furthermore, the regional statistics presented that positive correlations between the cloud optical thickness and cloud fraction with the aerosol column number concentration exist in most regions consistent with the global mean statistics. However, the effective cloud particle radius showed a tendency similar to the global correlation only around the seashore regions. Using these correlations and assuming that the aerosol column number concentration has increased by 30% from the preindustrial era, the total radiative forcing of the aerosol indirect effect was evaluated to be about −0.6 to −1.2 W m−2. The radiative forcing of the aerosol direct effect from the satellite-retrieved parameters was also evaluated as −0.4 W m−2 over the ocean. The cloud-top temperature was found to be insensitive to the change in the aerosol number, although there was a distinct negative correlation between the aerosol number and cloud temperature at which the cloud particle grows to a radius of 14 μm. This particular dependency of the cloud temperature suggests that aerosols acts on clouds so as to change cloud particle size near the cloud top, optical thickness, and fraction but to keep their cloud-top temperature without causing a significant longwave radiative forcing.

Received 26 December 2002; accepted 20 May 2003; published 21 November 2003.

Citation: Sekiguchi, M., T. Nakajima, K. Suzuki, K. Kawamoto, A. Higurashi, D. Rosenfeld, I. Sano, and S. Mukai (2003), A study of the direct and indirect effects of aerosols using global satellite data sets of aerosol and cloud parameters, J. Geophys. Res., 108(D22), 4699, doi:10.1029/2002JD003359.

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