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Title: VARIATION OF HYDROMETEOROLOGICAL CONDITIONS ALONG A TOPOGRAPHIC TRANSECT IN NORTHWESTERN MEXICO DURING THE NORTH AMERICAN MONSOON

Author
item VIVONI, E - NM INST OF MINING & TECH
item GUTIERREZ-JURADO, H - NM INST OF MINING & TECH
item ARAGON 1, C - NM INST OF MINING & TECH
item MENDEZ-BARROSO, L - NM INST OF MINING & TECH
item RIENHART, A - NM INST OF MINING & TECH
item WYCKOFF, R - NM INST OF MINING & TECH
item RODRIGUEZ, J - INSTITUTO DEL MEDIO AMBIE
item WATTS, C - UNIVERSITY OF SONORA
item Bolten, John
item LAKSHMI, V - UNIV. OF SOUTH CAROLINA
item Jackson, Thomas

Submitted to: Journal of Climate
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/20/2006
Publication Date: 11/30/2006
Citation: Vivoni, E.R., Guiterrex-Jurado, H.A., Aragon, C.A., Mendez-Barroso, L.A., Reinhart, A.J., Wyckoff, R.L., Rodriguez, J.C., Watts, C.J., Bolten, J.D., Lakshmi, V., Jackson, T.J. 2007. Variation of hydometerological conditions along a topographic transect in northwestern Mexico during the North American Monsoon. Journal of Climate. 20:1792-1809.

Interpretive Summary: Land-atmosphere interactions at the basin scale (~100 km2), obtained via a technique accounting for topographic variability, revealed the role played by the land-surface in sustaining high atmospheric moisture conditions, with implications towards rainfall generation during the North American monsoon. The North American monsoon is a critical source of water for the western U.S. Relatively little was known about the spatiotemporal variability of land-surface conditions during the North American monsoon, in particular for regions of complex topography. As a result, the role played by land-atmosphere interactions in generating convective rainfall over steep terrain and sustaining monsoon conditions is still poorly understood. Here, this was investigated by monitoring the variation of hydrometeorological conditions along a large-scale topographic transect in northwestern Mexico on a daily basis at thirty sites selected to represent variations in elevation and ecosystem distribution in early August 2004.The linkage of atmospheric variables to surface conditions, indicating that heating and moistening of the boundary layer closely follows spatial and temporal changes in hydrologic properties, is a significant contribution to understanding the processes that drive a major source of water for western U.S. agriculture and society.

Technical Abstract: Relatively little is currently known about the spatiotemporal variability of land-surface conditions during the North American monsoon, in particular for regions of complex topography. As a result, the role played by land-atmosphere interactions in generating convective rainfall over steep terrain and sustaining monsoon conditions is still poorly understood. In this study, we describe the variation of hydrometeorological conditions along a large-scale topographic transect in northwestern Mexico. The transect field experiment consisted of daily sampling at thirty sites selected to represent variations in elevation and ecosystem distribution. Simultaneous soil and atmospheric variables were measured during a two week period in early August 2004. Transect observations were supplemented by a network of continuous sampling sites used to analyze the regional hydrometeorological conditions prior to and during the field experiment. Results reveal the strong control exerted by topography on the spatial and temporal variability in soil moisture, with distinct landscape regions experiencing different hydrologic regimes. Reduced variations at the plot- and transect-scale during a drydown period indicate that homogenization of hydrologic conditions occurred over the landscape. Furthermore, atmospheric variables are clearly linked to surface conditions, indicating that heating and moistening of the boundary layer closely follows spatial and temporal changes in hydrologic properties. Land-atmosphere interactions at the basin scale (~100 km2), obtained via a technique accounting for topographic variability, further reveal the role played by the land-surface in sustaining high atmospheric moisture conditions, with implications towards rainfall generation during the North American monsoon.