1. COSMIC-based studies of synoptic-scale cyclones over the West Antarctic Ice Sheet (WAIS)
NASA funded, collaborative project with OSU
WAIS is a key location in the global climate change. - Recent observation of dramatic warming and rapid reduction of ice mass - Subsequent sea level rise and positive feedback to warming are main concerns
Synoptic-scale storms over the WAIS - Major source of water mass (snowfall) that can counterbalance recent ice loss - Causes inclement weather that interferes with logistics activity at McMurdo - Need to better understand the structure and developing mechanism (little is known so far compared to other areas on the globe)
Expected value of COSMIC (GPS RO) data Performance of most satellite data over the region is poor (due to surface emission, cloudiness, extreme coldness) Lacks conventional data, especially about vertical structure COSMIC can provide valuable information on the vertical structure of the storm, penetrating deep layer of clouds
2007/12/08_00-15_00 GPS RO: 1924
2007/12/12_18UTC: 923 hPa
Shu-Ya Chen

2. Approach : - WRF-Var with NCEP analysis as first guess
- Assess impact of GPS RO data by data denial experiment
Preliminary Findings : Shows slight positive impact in storm track and intensity
- GPS RO data bring warm and wet changes around the storm in the forecast, providing favorable conditions for the storm’s development
- Impact of GPS RO data are sensitive to various parameters in the system (model’s resolution, initial time, assumed background and observation errors,…etc). Tuning them all requires significant work - A few bugs in WRF-Var, relevant to GPS RO, have been found and fixed - A local bending angle operator has been implemented and is under testing
Near future plan: Closer looking in the changes made by GPS RO data that affects simulated storm’s life
- Understanding physical/dynamical mechanisms associated with the storm’s structure and development using the GPS RO data not assimilated into WRF-Var
- Comparison of observation operators (e.g. nonlocal operator or local bending angle operator)