WSR-88D Radar Data and NLDN Lightning Data Assimilation at NCEP

The radial winds and reflectivity from the WSR-88D radar network and lightning data from NLDN network are assimilated within North American Mesoscale Forecast System Version 4 (NAMv4).  This effort is consistent with the scope and goals of the National Weather Service’s Next Generation Global Prediction System (NGGPS) which include improvement and unification of data assimilation techniques at all scales.

The radial wind is directly analyzed by NCEP’s Grid-point Statistical Interpolation (GSI) analysis system. The cloud analysis package developed by the NOAA Earth System Research Laboratory’s Global Systems Division is adapted for assimilation of WSR-88D radar reflectivity and lightning data within the NAMv4 system. Lightning data from NLDN are used to retrieve radar reflectivity. The retrieved radar reflectivity from lightning data together with radar reflectivity from WSR88D network, surface observations and satellite cloud products are used to update the hydrometeors and derive a temperature tendency in GSI. The hydrometeors and temperature tendency are further used in the forward integration of the digital filter initialization (DFI). The impact of radar and lightning data assimilation on the skill of resulting NAMv4 forecasts will be presented.