P13     Combined application of Variational Local Analysis and Prediction System and nudging data assimilation

 

Reen, Brian, Army Research Laboratory (ARL), Yuanfu Xie, National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL), Huaqing Cai, ARL, Steve Albers, NOAA/ESRL and Cooperative Institute for Research in the Atmosphere, Colorado State University (CIRA), Robert Dumais, Jr., ARL, and Hongli Jiang, NOAA/ESRL and CIRA

 

The potential value of combining Variational Local Analysis and Prediction System (vLAPS) analyses and nudging data assimilation is investigated using 1-km WRF simulations for a case day with strong convection over the Southern Great Plains region.  The vLAPS analyses can incorporate a wide variety of observations, including observations such as radar that are difficult to assimilate via nudging.  However, its 3DVAR analysis is not ideal in maintaining dynamic and thermodynamic balance. Nudging allows for a gradual and persistent application of the effects of observations, unlike the sudden and single application of the effects of observations in the usual application of vLAPS analyses.  Nudging should be able to improve vLAPS dynamic and thermodynamic balances. Thus, the combination of vLAPS and nudging could potentially result in significant forecast improvement. Experiments are completed that investigate applying a single vLAPS analysis at the initial time, combining this with analysis nudging towards a series of vLAPS analyses during a pre-forecast time period, applying no data assimilation, and other variations of the data assimilation.  The experiments are carried out for a series of cycles to expand the limited generality provided by investigating a single case day.