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United States Department of Agriculture

Agricultural Research Service

Title: Large Scale Measurements of Soil Moisture for Validation of Remotely Sensed Data: Georgia Soil Moisture Experiments of 2003

Authors
item Bosch, David
item Lakshmi, V. - UNIV OF S. CAROLINA
item Jackson, Thomas - ARS BELTSVILLE
item Jacobs, Jennifer - UNIV OF NEW HAMPSHIRE

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 18, 2005
Publication Date: May 30, 2006
Citation: Bosch, D.D., Lakshmi, V., Jackson, T.J., Jacobs, J.M. 2006. Large scale measurements of soil moisture for validation of remotely sensed data: Georgia soil moisture experiments of 2003. Journal of Hydrology. 323(2006):120-137.

Interpretive Summary: The moisture content of the soil can affect many geophysical processes in the environment including hydrology, climate, and plant/soil interactions. Knowledge of the amount of water existing in the soil is critical to understanding many fundamental environmental processes. In order to better understand the variance of soil moisture across the landscape and the relationships between the soil moisture and landscape characteristics, a series of Soil Moisture Experiments were conducted in 2003 (SMEX 03). One component of this research was conducted in South Central Georgia of the U.S., from June 17th to July 21st, 2003. Forty-nine sites across a 3750 km2 area representing a diversity of land covers were visited once a day for ten days. Soil moisture was found to be very responsive to rainfall, landscape position, and depth in the profile. An examination of soil moisture observed within different land covers indicated that while they follow the same trends, soil moisture can vary with land use. Pasture sites were consistently the wettest while row crop sites were normally the driest.

Technical Abstract: There is a growing demand in both research and application for accurate soil moisture measurements both at small (e.g. plant-soil) and large (e.g. regional climate) scales. Remote sensing is one of the tools currently being examined for obtaining these measurements. While several current instruments aboard various satellites yield estimates which can be used to infer soil moisture, testing of these sensors has been limited to a very small fraction of the world. To fill this gap, a series of Soil Moisture Experiments were conducted in 2003 (SMEX 03) to provide data for testing of these instruments. One component of this research was conducted in South Central Georgia of the U.S., from June 17th to July 21st, 2003. Soil moisture and temperature data collected from June 23rd to July 2nd provided the ground measurements for this project. Forty-nine sites representing a diversity of land covers were visited once a day for the ten days of the soil-based regional sampling. Soil moisture in the top 0 to 1 cm of the soil profile was found to be more responsive to precipitation and to have greater variability than soil moisture at the 0-3 or the 3-6 cm depths. Soil moisture increased with depth during drying conditions and decreased with depth following the precipitation events. An examination of soil moisture observed within different land covers indicated that while they follow the same trends, soil moisture can vary with land use. Pasture sites were consistently the wettest while row crop sites were normally the driest.

Last Modified: 9/23/2014
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