090600Z

1. Init. At 2006090600Z Init. At 2006090700Z Init. At 2006090800Z 090800Z 9 GOSRO soundings, 2006090600Z 5 GOSRO soundings, 2006090700Z 090700Z 090600Z 3 GOSRO soundings, 2006090800Z Download the bfrPrf (BUFR) data from CDAAC Decode the bfrPrf data to be a LITTLE_R ASCII file This GPSRO LITTLE_R file could be merged with the LITTLE_R files for all other types of observations 3DVar OBS preprocessor To get the 3DVAR Observation file with the observation error assigned WRFVar (3DVar) The quality control (QC) procedure implemented in the innovation (O-B)calculation Preliminary Results of FORMOSAT-3/COSMIC Data Assimilation with WRF 3DVar Y.-R. Guo, H.-C. Lin, W. Wang, and Y.-H. Kuo National Center for Atmospheric Research, P. O. Box 3000, Boulder, CO 80307 Abstract Summary and conclusions The procedure for assimilation of FORMOSAT-3/COSMIC GPSRO data with WRFVar (3DVar) is introduced, which includes: i) to download bfrPrf data from CDAAC, ii) to decode the bfrPrf data to be a LITTLE_R ASCII file, which can be merged together with all other types of meteorological observations, iii) to prepare observation file for WRFVar (3DVar) with the LITTLE_R as input, and finally iv) to run WRFVar to assimilate the GPSRO and other types of observations. With the COSMIC data collected during the typhoon Saomai period (August 2006) and the CHAMP data collected during the typhoon Dujuan period (August 2003), the WRFVar results of (O-B) and (O-A) showed that the quality of the COSMIC data is comparable to the CHAMP data. In order to assess the added value of the COSMIC GPSRO data, two experiments were conducted for Hurricane Florence: Real-time WRF-ARW forecast and WRF-ARW forecast initiated with WRFVar (3DVar) assimilating the COSMIC GPSRO data only. For three different initial times, 0000 UTC 6, 7, and 8 September 2006, assimilation of the COSMIC GPSRO data showed the positive impact on the 120h track forecast although only few GPSRO soundings are available within the 6h time window over the 12 km resolution domain. • FORMOSAT-3/COSMIC GPSRO data can be successfully assimilated with the Local (Refractivity) observation operator in WRFVar (3DVar), including I) download the bfrPrf data from CDAAC; 2) decode the bfrPrf data to be a LITTLE_R ASCII file; 3) preprocess (3DVAR_OBSPROC) the data to be a 3DVar obs file (obs_gts.3dvar); 4) WRFVar (3DVar). • The experiments with assimilation of GPSRO data for Hurricane Florence were conducted. In compared the results from 3DVar with those from the real-time WRF-ARW forecast, the COSMIC GPSRO data assimilation showed the positive impact on the track forecasts of Hurricane Florence although only few GPSRO soundings were available in this case. Results COSMIC GPSRO data preparation for WRFVar Track forecast from Exp. RT and 3DVAR for the different initial times For GPSRO refractivity, the observation errors vary with height and latitude (Chen and Kuo, 2005). Track forecast errors at the different initial times WRFVar (3DVar) for GPSRO data assimilation Observation operator Currently, only the local refractivity operator is implemented in WRFVar: Quality Control procedure for Refractivity N • Step 1. Background check: |(O-B)| > 5o • Step 2. Relative Error check: h =< 7 km, R.E. > 5.0% 7 km < h < 25 km, R.E > 4.0% h >= 25 km, R.E> 10.0% • Step 3. Low level check: if the data at certain level fails to pass relative error check, all the data below that level will be discarded. Red numbers indicate the smaller errors between Exp.RT and 3DVAR. Innovations (O-B) before quality control COSMIC 2006 August (Saomai) 113 GPSRO soundings COSMIC GPSRO Soundings for Hurricane Florence CHAMP 2003 August (Dujuan) 53 GPSRO soundings COSMIC GPSRO soundings distribution within 6h time window centered at 2006090600Z, 2006090700Z, and 2006090800Z Innovations (O-B) after quality control The number of the data points assimilated after quality Control procedure The percentages of the points relative to ingested points are shown in parenthesis Experiments for Hurricane Florence The averaged (O-B) and (O-A) of the GPS Refractivityfrom 3D-Var experiments with 6-h time window assimilation The RMS reduction percentages (O-A)/(O-B) are shown in parenthesis To asses the added values of COSMIC GPSRO data in Hurricane Florence forecasts, two experiments are conducted: Real time WRF-ARW Hurricane forecast (Wei Wang) Initial condition from GFDL Hurricane model and the boundary condition from GFS forecasts domain size: 502x301x35, grid size: 12-km WRFVar (3DVar) assimilation COSMIC GPSRF data only First guess: the initial condition used in real-time WRF-ARW Hurricane forecast Background Error statistics: CV5 BE interpolated from a 12-km (460x351x51) CV5 BE over the north America and Atlantic (derived by Zhiquan Liu) Observations: FORMOSAT-3/COSMIC GPS Refractivity soundings. The experiments were conducted for three initial times: 2006090600Z, 2006090700Z and 2006090800Z, and the forecast length is 120h. Hurricane FlorenceThe track from 2100 UTC 3 to 2100 UTC 12 September 2006 with 6h interval COSMIC data from brfPrf with 200 m resolution for 113 GPSRO soundings (2 days) (The bad flag (or pccf < 100) was turned off for COSMIC data). CHAMP data from wetPrf with 100 m resolution for 53 GPSRO soundings (3 days) 7th ANNUAL WRF USER’S WORKSHOP 16-18 October 2006, Boulder, Colorado, USA