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

Monday, 23 January 2012
Experiments of WRF Variational Data Assimilation on the Forecast of An Antarctic Cyclone
Hall E (New Orleans Convention Center )
Kekuan Chu, Nanjing, China; and Q. Xiao and C. Liu

A suite of data assimilation experiments were designed to evaluate the impact of different assimilation schemes on the forecast of an Antarctic synoptic cyclone over the Ross Sea/Ross Ice Shelf region. The Weather Research and Forecasting (WRF) model and its 3/4-dimensional variational data assimilation (3/4DVAR) system were employed in this study. Both high-resolution 3DVAR and 4DVAR showed their potential to further improve the weather analysis and forecast over Antarctica. Within the Ross Sea/Ross Ice Shelf region, which was under the influence of the synoptic cyclone, the surface wind and temperature forecast were significantly improved. Particularly, high-resolution 3DVAR assimilation experiment showed the best surface temperature forecast over the Ross Sea/Ross Ice Shelf region. 4DVAR experiment also had better surface temperature forecast than low-resolution 3DVAR assimilation experiments over this region, and it even out-performed than high-resolution 3DVAR assimilation experiment beyond 24 hours. Verifications over the whole Antarctic continent indicated that high-resolution 3DVAR assimilation experiment had lowest analysis errors and had best forecast during first 24 hours. However, with the increase of forecast lead time, 4DVAR assimilation experiments quickly caught up and showed comparable or better performance than high-resolution 3DVAR assimilation beyond 24 hours. Additional assimilation experiment showed that assimilating of QuikSCAT surface wind observations had a positive impact on the wind forecast over the Antarctic continent, indicating the potential value of such data on weather analysis and forecast over the high-latitude regions.

Supplementary URL: