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Read Full Article (file size: 256128 bytes) Cited by
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 112,
D09117,
doi:10.1029/2006JD007505,
2007
Observational estimates of radiative forcing due to land use change in southwest Australia
Udaysankar S. Nair
Earth System Science Center, National Space Science and Technology Center, University of Alabama, Huntsville, Alabama, USA
Deepak K. Ray
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
Jun Wang
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
Sundar A. Christopher
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
Tom J. Lyons
School of Environmental Science, Murdoch University, Murdoch, Western Australia, Australia
Ronald M. Welch
Department of Atmospheric Sciences, University of Alabama, Huntsville, Alabama, USA
R. A. Pielke Sr.
Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA
Abstract
Radiative forcing associated with land use change is largely derived from global circulation models (GCM), and the accuracy
of these estimates depends on the robustness of the vegetation characterization used in the GCMs. In this study, we use observations
from the Clouds and Earth's Radiant Energy System (CERES) instrument on board the Terra satellite to report top-of-the-atmosphere
(TOA) radiative forcing values associated with clearing of native vegetation for agricultural purposes in southwest Australia.
Over agricultural areas, observations show consistently higher shortwave fluxes at the TOA compared to native vegetation,
especially during the time period between harvest and planting. Estimates using CERES observations show that over a specific
area originally covered by native vegetation, replacement of half the area by croplands results in a diurnally averaged shortwave
radiative forcing of approximately −7 W m−2. GCM-derived estimates for areas with 30% or more croplands range from −1 to −2 W m−2 compared to observational estimate of −4.2 W m−2, thus significantly underestimating radiative forcing due to land use change by a factor of 2 or more. Two potential reasons
for this underestimation are incorrect specification of the multiyear land use change scenario and the inaccurate prescription
of seasonal cycles of crops in GCMs.
Received 12
May
2006;
accepted 22
November
2006;
published 15
May
2007.
Keywords: Australia;
land use change;
radiative forcing.
Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions (0426, 1610); 1631 Global Change: Land/atmosphere interactions (1218, 1843, 3322); 1632 Global Change: Land cover change; 1843 Hydrology: Land/atmosphere interactions (1218, 1631, 3322); 3359 Atmospheric Processes: Radiative processes.
Read Full Article (file size: 256128 bytes) Cited by
Citation: Nair, U. S., D. K. Ray, J. Wang, S. A. Christopher, T. J. Lyons, R. M. Welch, and R. A. Pielke Sr.
(2007),
Observational estimates of radiative forcing due to land use change in southwest Australia,
J. Geophys. Res.,
112,
D09117,
doi:10.1029/2006JD007505.
Copyright 2007 by the American Geophysical Union.
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