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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, D03113, doi:10.1029/2004JD005160, 2005

Impact of agricultural practice on regional climate in a coupled land surface mesoscale model

H. S. Cooley

Energy and Resources Group, University of California, Berkeley, California, USA
Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA

W. J. Riley

Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA

M. S. Torn

Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA

Y. He

Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA

Abstract

The land surface has been shown to form strong feedbacks with climate due to linkages between atmospheric conditions and terrestrial ecosystem exchanges of energy, momentum, water, and trace gases. Although often ignored in modeling studies, land management itself may form significant feedbacks. Because crops are harvested earlier under drier conditions, regional air temperature, precipitation, and soil moisture, for example, affect harvest timing, particularly of rain-fed crops. This removal of vegetation alters the land surface characteristics and may, in turn, affect regional climate. We applied a coupled climate model (MM5) and land surface model (LSM1) to examine the effects of early and late winter wheat harvest on regional climate in the Department of Energy Atmospheric Radiation Measurement (ARM) Climate Research Facility in the Southern Great Plains, where winter wheat accounts for 20% of the land area. Within the harvested, winter wheat region, simulated 2 m air temperature was 1.3°C warmer in the early harvest scenario at midday averaged over the 2 weeks following harvest. Soils in the harvested area were drier and warmer in the top 10 cm and wetter in the 10–20 cm layer compared to those in the late harvest. Midday soils were 2.5°C warmer in the harvested area at midday averaged over the 2 weeks following harvest. Harvest also dramatically altered latent and sensible heat fluxes. Although differences between scenarios diminished once both scenarios were harvested, the short-term impacts of land management on climate were comparable to those from land cover change demonstrated in other studies.

Received 24 June 2004; accepted 1 November 2004; published 10 February 2005.

Keywords: regional climate; land use change; Southern Great Plains.

Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions (0426, 1610); 1620 Global Change: Climate dynamics (0429, 3309); 3322 Atmospheric Processes: Land/atmosphere interactions (1218, 1631, 1843); 9350 Geographic Location: North America.

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Citation: Cooley, H. S., W. J. Riley, M. S. Torn, and Y. He (2005), Impact of agricultural practice on regional climate in a coupled land surface mesoscale model, J. Geophys. Res., 110, D03113, doi:10.1029/2004JD005160.

This paper is not subject to U.S. copyright. Published in 2005 by the American Geophysical Union.