REBAL-92 - A COOPERATIVE RADIATION AND ENERGY-BALANCE FIELD-STUDY FORIMAGERY AND ELECTROMAGNETIC PROPAGATION

The surface energy balance directly affects vertical gradients in temp erature and specific humidity within the atmospheric surface layer, an d these gradients influence optical turbulence. This study was conduct ed to improve current understanding of the partitioning of energy at t he ground surface of a bare soil field and its influence on the charac ter and intensity of optical turbulence as represented by the refracti ve index structure parameter, C-n(2), and to improve micrometeorologic al models of the surface energy balance. The field study entitled ''Ra diation Energy Balance Experiment for Imagery and Electromagnetic Prop agation'' was conducted by the United States Army Atmospheric Sciences Laboratory and the United States Department of Agriculture Agricultur al Research Service, at Bushland, Texas, during May and July 1992. The following were collected: diurnal radiation; evaporation (directly me asured by large weighing lysimeters); five-level micrometeorological p rofiles of wind speed, air temperature, and relative humidity; soil te mperature and volumetric water content; soil heat flux; optical turbul ence (scintillometer); and near- and far-field infrared imager data ov er wet and dry bare soil for clear and cloudy sky conditions. Initial results from the modeling efforts indicate excellent agreement between measured and modeled values of radiation/energy balance fluxes and C( n)-2, for one day. Future model evaluation will extend over the wide r ange of conditions encountered during the field study.