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. |