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General Circulation Models (fvGCM)

Forecasts of Katrina's Track, Intensity, Structures with a Global Mesoscale Model

It is known that General Circulation Models (GCMs) have insufficient resolution to accurately simulate hurricane near-eye structure and intensity. Their physics packages (e.g., cumulus parameterizations) are also known limiting factors in simulating hurricanes.

Six 5-day simulations of Katrina at both 0.25o and 0.125o show comparable track forecasts, but the higher-resolution (0.125o) runs provide much better intensity forecasts, producing the center pressure with errors of only +- 12 hPa. Realistic near-eye wind distribution and vertical structure are also obtained as cumulus parameterizations are disabled.

Shen, B.-W., R. Atlas, O. Reale, S.-J. Lin, J.-D. Chern, J. Chang, C. Henze, J.-L. Li, 2006: Hurricane Forecasts with a Global Mesoscale-resolving model: Preliminary results with Hurricane Katrina (2005). GRL, 33, L13812, doi:10.1029/2006GL026143.

 

Landfall errors:

e32 (1/4o): 50km, g48(1/8o): 14km, g48ncps (1/8o w/o CPs): 30km
GFS Analysis (~35km) valid at 08/29/12z 96 h Simulations with no CPS High-resolution runs simulate realistic intensity, RMW (radius of max wind) and warm core (shaded)

 

Near-eye Wind Distributions in a 2ox2o box (a) AOML high-resolution surface wind analysis, (b) the 0.25o 99h simulations, (c) the 0.125o 99h simulations, (d) the 0.125o 96h simulations without convection parameterizations (CPs).