Soil Moisture Measurements And Their Applications At The Savannah River Site

Download or read book Soil Moisture Measurements and Their Applications at the Savannah River Site written by and published by . This book was released on 2000 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil moisture is a very important component of the land-atmosphere exchange. Practically, it is valuable in both the agricultural and meteorological industries. Farmers require soil moisture for crop yields, while the atmospheric numerical modeling community has found soil moisture to be extremely important in generating realistic forecasts. Physically, the soil moisture not only provides water vapor for precipitation through evapotranspiration and controls the splitting of net radiation into sensible and latent heat components, but it also provides thermal inertia to the climate through heat storage and release from large water reservoirs (Famiglietti et al. 1998). Quantification of soil moisture is challenging since the range of spatial scale varies from centimeters to thousands of kilometers, while temporal scales vary from minutes to months. In the short term, soil moisture is influenced by topography, soil type, texture, and vegetation and affects the infiltration of water into and through the soil, as well as how much water will be held within the soil. In the long term, soil moisture is impacted by atmospheric forcing and affects the amount of water available to the soil through rain (or snowmelt), as well as removal by evapo-transpiration (Entin et al. 2000). Due to the expense and difficulty of measuring soil moisture, few extensive data sets currently exist. Exceptions include those found in Russia (dating back to the 1930s), Mongolia (1973-1995), China (1981-1991), India (1987-1995), and the US (Illinois, Iowa and Oklahoma, from the early 1980s to the present), (Robock et al. 2000). Most of these data were taken several times per month and do not provide high-frequency variations in time. A real-time, operational monitoring network for soil moisture detection has very important ramifications in the satellite industry, where such measures could serve as a ground truth. This paper discusses a real-time soil monitoring station that has been established at the Savannah River Site (SRS), located in the southeastern US, which provides 15-minute average soil moisture data. The measurement technique is first discussed, along with characteristics of the observation sites. Several applications of the monitoring are then examined. This includes the use of soil moisture as a decision-making tool in performing prescribed fires of the local forest vegetation. Since soil moisture measurements are also very important in the proper determination of surface fluxes in atmospheric models, a comparison of these point measurements with the National Center for Atmospheric Predictions (NCEP) model simulations over an extended period of time are examined. Finally, simple expressions describing the temporal variation of the soil moisture with precipitation events at the SRS are discussed.