Re: This Is Driving Me Nuts
Posted by Chris in Tampa on 8/27/2011, 8:27 pm
The global models are understandable. I believe the reason why they don't initialize with the lowest pressure is because the resolution is not great enough to pick it up. But, I don't know why the GFDL would be off. I know some of them can use the global models at times, but I there are special versions for that.

I just looked at the NHC Model Page:
http://www.nhc.noaa.gov/modelsummary.shtml
And read this:

--------------

"NWS Geophysical Fluid Dynamics Model (GFDL) Hurricane Model

The GFDL Hurricane Model is a limited-area, triply-nested grid-point model designed specifically for TC prediction. This grid configuration along with other technical specification for the GFDL can be found in Table 3. The GFDL is run for up to four TCs every six hours out to 126 hours as requested by NHC and CPHC. The high resolution of the GFDL allows it to resolve relatively small-scale features within a TC such as the eye and eyewall. Still, even the GFDL is not able to fully resolve the highly complex structure of a TC. The GFDL is coupled with a high-resolution version of the Princeton Ocean Model (POM), which allows TC-induced ocean modification, such as sea-surface temperature cooling, and partially accounts for the feedback of the modified ocean on the TC. In the Atlantic, the POM is three dimensional with 23 vertical levels. In the eastern North Pacific where ocean currents and sea surface temperature gradients are more predictable, only a one-dimensional POM is used. In the GFDL analysis, the GFS TC vortex is replaced with an axisymmetric vortex spun up in a separate model simulation. The axisymmetric vortex model utilizes TC specifications as provided by NHC forecasters.

Since the horizontal resolution of the GFDL is sufficiently high to represent some of the inner core TC structure, the GFDL model has up to now been the only purely dynamical model that can provide both skillful intensity and track forecasts (http://www.nhc.noaa.gov/verification/verify3.shtml).

While it is still used operationally, there are no plans to further develop the GFDL Hurricane Model. However, the GFDN model, which currently has resolution and physics similar to the GFDL, will continue to be improved. See the section below for details on the GFDN."

--------------

That may indicate that the initial conditions are set by another model. Don't quite get how all that works, but maybe that could explain why it was off. Or in this particular case the resolution was still not quite good enough? Don't know.
173
In this thread:
This Is Driving Me Nuts - Target, 8/27/2011, 8:12 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.