1 WRFDA 2009 Updates Xiang-Yu Huang National Center for Atmospheric Research, Boulder, CO, USA 1. Overview WRFDA - the Weather Research and Forecasting (WRF) Data Assimilation system is a component of the WRF modeling system developed at the National Center for Atmospheric Research. WRFDA is an advanced data assimilation system, contained with the WRF software that provides state-of-art 3D/4D variational (3D/4D-Var) and hybrid variational/ ensemble techniques (Barker et al. 2004; Huang et al. 2009a; Wang et al. 2008). With the recent release, version 3.1, WRFDA can assimilate: • In-Situ observations: o Surface (SYNOP, METAR, SHIP, BUOY). o Upper air (TEMP, PIBAL, AIREP, ACARS, TAMDAR). • Remotely sensed observations: o Atmospheric Motion Vectors (geo/polar). o SATEM thickness. o Ground-based GPS Total Precipitable Water/Zenith Total Delay. o SSM/I oceanic surface wind speed and TPW. o Scatterometer oceanic surface winds. o Wind Profiler. o Radar radial velocities and reflectivities. o Satellite temperature/humidity/thickness profiles. o GPS refractivity (e.g. COSMIC). • Radiances (using RTTOV or CRTM): o HIRS NOAA-16, NOAA-17, NOAA- 18, METOP-2 o AMSU-A NOAA-15, NOAA-16, NOAA-18, EOS-Aqua, METOP-2 o AMSU-B NOAA-15, NOAA-16, NOAA-17 o MHS NOAA-18, METOP-2 o AIRS EOS-Aqua o SSMIS DMSP-16 • Bogus data o TC bogus o Global bogus Corresponding author address: National Center for Atmospheric Research, Mesoscale and Microscale Meteorology Division, P.O. Box 3000, Boulder, CO 80307- 3000. Email: huangx@ucar.edu WRFDA is used in both applied and research settings. It is used as the analysis component of several international operational data assimilation systems. It is also used by those centers, as well as by university and research institutions, for data assimilation research. WRFDA is a community data assimilation asset that is maintained and supported by NCAR. In 2009, NCAR developed the WRFDA website where one can browse, or download WRFDA documentation, tutorials, test data, participate in user forums, and obtain the latest code. See http://www.mmm.ucar.edu/wrf/users/wrfda WRFDA development and support is provided by a dedicated team of NCAR scientists. Those scientist works with the international data assimilation community to improve the scientific and software engineering aspects of WRFDA. The international community interacts with NCAR’s WRFDA team through various channels: (i) NCAR’s visiting scientist program, (ii) WRFDA user forums and workshops, (iii) bi-annual tutorials, (iv) an online support facility, called WRF-Help, (v) collaborative operational center research projects, and (vi) university/graduate student research projects. Generally, the WRFDA workshops and tutorials are held at the NCAR facilities in Boulder, Colorado, USA. Occasionally they are held overseas to accommodate user community needs. For the benefit of the community, NCAR posts all tutorial presentations at http://www.mmm.ucar.edu/wrf/users/wrfda/tutorial.html