Measurements of Soil Surface Roughness During the Fourth Microwave Water and Energy Balance Experiment: April 18 - June 13, 2005¹

Mi-young Jang, Kai-Jen Calvin Tien, Joaquin Casanova, and Jasmeet Judge²

Abstract - Circular 1483

For accurate prediction of weather and near-term climate, root-zone soil moisture is one of the most crucial components driving the surface hydrological processes. Soil moisture in the top meter is also very important because it governs moisture and energy fluxes at the land-atmosphere interface and it plays a significant role in partitioning of the precipitation into runoff and infiltration.

Energy and moisture fluxes at the land surface can be estimated by Soil-Vegetation-Atmosphere-Transfer (SVAT) models. These models are typically used in conjunction with climate prediction models and hydrological models. Even though the biophysics of moisture and energy transport is well-captured in most current SVAT models, the computational errors accumulate over time and the model estimates of soil moisture diverge from reality. One promising way to improve significantly the model estimates of soil moisture is by assimilating remotely sensed data that is sensitive to soil moisture, for example microwave brightness temperatures, and updating the model state variables.

The microwave brightness at low frequencies (< 10 GHz) is very sensitive to soil moisture in the top few centimeters in most vegetated surfaces. It is also sensitive to soil surface roughness.

Surface roughness was measured as part of the Fourth Microwave Water and Energy Balance Experiment (MicroWEX-4). More details regarding observations during the MicroWEX-4 can be found at http://edis.ifas.ufl.edu/AE362.pdf

This publication contains the detailed information regarding the soil surface roughness measurements conducted as part of the MicroWEX-4. To view the entire publication, see the accompanying PDF file on EDIS:

http://edis.ifas.ufl.edu/pdffiles/AE/AE36300.pdf

For related documents, please visit:

http://edis.ifas.ufl.edu/AE288

Field Data Report for the First Microwave Water and Energy Balance Experiment (MicroWEX-1), July 17 - December 16, 2003, Citra, Florida

http://edis.ifas.ufl.edu/pdffiles/AE/AE36000.pdf

Field Data Reprt for the Second Microwave Water and Energy Balance Experiment (MIcroWEX-2): from March 17 through June 3, 2004

http://edis.ifas.ufl.edu/pdffiles/AE/AE36100.pdf

Field Observations During the Third Microwave Water and Energy Balance Experiment (MicroWEX-3): June 16 - December 21, 2004

http:/edis.ifas.ufl.edu/pdffiles/AE/AE36200.pdf

Field Observations During the Fourth MIcrowave Water and Energy Balance Experiment (MicroWEX-4): March 10 - June 14, 2005

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Footnotes

1. This document is Circular 1483, one of a series of the Agricultural and Biological Engineering Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: November 2005. Please visit the EDIS Web site at http://edis.ifas.ufl.edu for more publicaitons.

2. Mi-young Jang and Kai-Jen Calvin Tien are graduate research assistants; Joaquin Casavova is an undergraduate research assistant; and Jasmeet Judge is Assistant Professor and Director of the Center for Remote Sensing (email: jasmeet@ufl.edu). All authors are affiliated with the Agricultural and Biological Engineering Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.

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The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.