Sensitivity of Tropical Land Climate to Leaf Area Index:
Role of Surface Conductance versus Albedo

Katrina Hales, J. David Neelin and Ning Zeng
J. Climate, 17, 2004.

Paper (PDF 1.4 MB)
© Copyright 2003 by the American Meteorological Society.

Abstract. Tropical land climate sensitivities to surface properties are studied using an intermediate complexity atmosphere model. We focus on land surface vegetation feedbacks to the atmosphere through surface conductance and albedo. Both properties are linked by a parameterization on leaf area index so that their relative impacts can be compared. For a given percent change in leaf area index, we find that low and moderate vegetation regions such as the Sahel have a higher sensitivity than rainforest regions such as the Amazon in local total precipitation anomaly as well as fractional change in precipitation. Comparison of sensitivities to changes in surface conductance and albedo shows that neither is negligible and their relative influence differs among local climatic regions, typified by different vegetation types. High precipitation rainforest regions are more influenced by surface conductance due to the large water recycling ratio there, while albedo has a larger influence in arid, low vegetation regions by modifying the energy balance and large-scale atmospheric circulation. In regions of moderate precipitation and vegetation, altered surface conductance and albedo have comparable effects on precipitation. Surface conductance and albedo have opposing effects on surface temperature but surface conductance has the dominant impact on both surface temperature and evapotranspiration.

Citation. K. Hales, J. D. Neelin and N. Zeng, 2004: Sensitivity of tropical land climate to leaf area index: Role of surface conductance versus albedo. J. Climate, 17, 1459-1473.

Acknowledgments. This research was supported in part by National Science Foundation grant ATM-0082529, National Oceanographic and Atmospheric Administration grant NA 16GP2003 and National Aeronautics and Space Administration grant NA G5-9358. P>


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