92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Thursday, 26 January 2012: 1:45 PM
Impact of Different Wind Lidar Configurations on NCEP Forecast Skill
Room 340 and 341 (New Orleans Convention Center )
Zaizhong Ma, JCSDA, Camp Springs, MD; and L. P. Riishojgaard, M. Masutani, and J. Woollen

The Global Wind Observing Sounder (GWOS) concept, which developed by NASA in response to the National Research Council (NRC) Decadal Survey, is expected to provide global wind profile observations with high vertical resolution, precision, and accuracy. The assimilation of space based Doppler wind LIght Detection And Ranging (Lidar) from the GWOS concept is being conducted in the Observing System Simulation Experiments (OSSEs) at the Joint Center for Satellite and Data Assimilation (JCSDA). A companion papers describe the realistic simulation of this Lidar wind data and evaluate the Four-telescope impact of GWOS to the global Numerical Weather Prediction (NWP), whereas this paper sets out to assess the impact of different pairs of telescopes from GWOS in meteorological analyses and forecasts. To this end, the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System [Gridpoint Statistical Interpolation/Global Forecast System (GSI/GFS)] was used, at a resolution of T382-64 layers, as the assimilation system and forecast model in this lidar OSSE study, and a set of six-week assimilation and forecast experiments from July 2 to August 15, 2005 have been set up and executed. Finally, the impacts from the different pairs of the GWOS telescopes were assessed by comparing the forecast results through 120 hours in this period. In this OSSE study, a control simulation utilizing all of the data types assimilated in the operational GSI/GFS system was compared to three OSSE simulation which added lidar wind data from the different pairs of telescopes (one-, two-, and four-look), respectively. First of all, the Root-Mean Squared Error (RMSE) of wind vector from analyses is investigated carefully against Nature Run. A significant reduction of the stratospheric RMSE of wind vector analyses is found for all latitudes when Lidar wind profiles are used in the assimilation system. Then the forecast impacts of Lidar data on the wind and temperature fields are also presented. In addition, the anomaly correlations (AC) of geopotential height forecasts at 500 hPa were evaluated to compare the control and different pairs of GWOS telescopes experiments. The results show that assimilation of the Lidar data from the GWOS (whatever one-, two-, or four-“look”) can improve the NCEP GFS wind and mass fields forecasts. Larger benefits are found in the southern hemisphere, although a significant positive impact is also found in the northern hemisphere.

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