General Seminar
May 29, 2007, 3:30 pm, Tuesday
Ismail Yucel, http://earth.engr.ccny.cuny.edu/noaa/html/people/faculty/yucel.html
Center for Atmospheric Sciences, Hampton University
Satellite Data Assimilation in Hydrometeorological Model systems
Data assimilation has been long recognized as an important tool for providing initial conditions for Numerical Weather Prediction (NWP) models and, recently, it has also been recognized as a mechanism for improving modeled diagnostic fields. Description and components of a NWP model is explained in the first part. Data assimilation techniques and their advantages in improving model estimates are followed in the second part. In an application to demonstrate how to incorporate observed data with model physics and dynamics, assimilation of satellite-derived cloud cover using nudging assimilation method in a NWP is presented. Three-dimensional cloud fields were created which took their horizontal distribution from the satellite image but derived their vertical distribution, in part, from the fields simulated by NWP during the time step immediately prior to assimilation and, in part, from the observed cloud-top height derived from the infrared band of GOES. Comparisons were made between modeled and observed data for model runs with and without cloud assimilation. Cloud assimilation substantially improved the ability of the NWP model to capture temporal and spatial variations in surface radiation and precipitation fields associated with cloud cover.