Thursday, 13 February 2003: 12:00 PM
The Validation of a Land Data Assimilation System (LDAS) Using Oklahoma Mesonet Data
The Oklahoma Mesonet is a network of 115 automated, hydrometeorological stations covering the state of Oklahoma. Each station measures air temperature and relative humidity at 1.5 m, wind speed and direction at 10 m, barometric pressure, rainfall, incoming solar radiation, and bare and vegetated soil temperatures at 10 cm below ground level. Approximately one-half of the sites measure supplemental parameters: temperature at 5 cm under bare and vegetated soil, and at 30 cm under vegetated soil. During 1996 soil moisture sensors were installed at 60 Oklahoma Mesonet sites at depths of 5, 25, 60, and 75 cm. In 1999, the Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) upgraded 89 sites with a suite of instruments capable of measuring components of the surface energy budget. In addition, a subset of 10 OASIS sites (designated OASIS Super Sites) were instrumented with sensors that are capable of measuring the components of the surface energy balance with enhanced accuracy.
The Land Data Assimilation System (LDAS) currently being developed in partnership between federal and university organizations seeks to improve the simulation of land surface states and energy fluxes in coupled land-atmosphere numerical models. This study validates the LDAS surface energy budget using independent observations from the 10 OASIS Super Sites. Energy fluxes are simulated using the MOSAIC land surface model. MOSAIC output, forced with Mesonet observations, are subsequently compared with OASIS Super Site data. Furthermore, simulations are conducted using the locally observed forcing at three different spatial scales. By doing so, this study investigates the response of the flux variables to spatial variability in forcing.