Improvements in the GFDL Hurricane Prediction System

View More View Less
  • 1 Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, New Jersey
© Get Permissions
Full access

Abstract

The hurricane model initialization scheme developed at GFDL was modified to improve the representation of the environmental fields in the initial condition. The filter domain defining the extent of the tropical cyclone in the global analysis is determined from the distribution of the low-level disturbance winds. The shape of the domain is generally not circular in order to minimize the removal of important nonhurricane features near the storm region. An optimum interpolation technique is used to determine the environmental fields within the filter domain. Outside of the domain, the environmental fields are identical to the original global analysis. The generation process of the realistic and model-compatible vortex has also undergone some minor modifications so that reasonable vortices are produced for various data conditions. The upgraded hurricane prediction system was tested for a number of cases and compared against the previous version and yielded an overall improvement in the forecasts of storm track. The system was run in an automated semioperational mode during the 1993 hurricane season for 36 cases in the Atlantic and 36 cases in the eastern Pacific basin. It demonstrated satisfactory skill in the storm track forecasts in many cases, including the abrupt recurvature of Hurricane Emily in the Atlantic and the landfall of Hurricane Lidia onto the Pacific coast of Mexico.

Abstract

The hurricane model initialization scheme developed at GFDL was modified to improve the representation of the environmental fields in the initial condition. The filter domain defining the extent of the tropical cyclone in the global analysis is determined from the distribution of the low-level disturbance winds. The shape of the domain is generally not circular in order to minimize the removal of important nonhurricane features near the storm region. An optimum interpolation technique is used to determine the environmental fields within the filter domain. Outside of the domain, the environmental fields are identical to the original global analysis. The generation process of the realistic and model-compatible vortex has also undergone some minor modifications so that reasonable vortices are produced for various data conditions. The upgraded hurricane prediction system was tested for a number of cases and compared against the previous version and yielded an overall improvement in the forecasts of storm track. The system was run in an automated semioperational mode during the 1993 hurricane season for 36 cases in the Atlantic and 36 cases in the eastern Pacific basin. It demonstrated satisfactory skill in the storm track forecasts in many cases, including the abrupt recurvature of Hurricane Emily in the Atlantic and the landfall of Hurricane Lidia onto the Pacific coast of Mexico.

Save