Vorticity dynamics of Typhoon Nuri (2008) evaluated from different model datasets

Measurements of Typhoon Nuri from tropical wave to typhoon stage were taken in August 2008 during the THORPEX Pacific Asian Regional Campaign (TPARC) and the Tropical Cyclone Structure experiment (TCS08). As Nuri intensified, two closed circulations in the storm-relative winds at 5km and 1.5km of height overlapped in a sheared environment and the vertical mass flux increased at low levels. A number of global datasets [the Global Forecast System (GFS) analysis, the Final FNL analysis, the Era-Interim reanalysis and the Climate Forecast System Reanalysis (CFSR)] are analyzed to evaluate how they represent these observed features during Nuri intensification. All global datasets show a larger sheared environment than observed, mainly due to larger wind speeds at middle and higher levels. Despite its coarse horizontal resolution (1 deg. x 1 deg.), the FNL analysis show a reasonable good agreement with observations. On the contrary, ERA-Interim shows the worst agreement. To better evaluate the large-scale dynamics of Nuri, the vorticity budget is also analyzed with these datasets.