Re: Model question
Posted by Chris in Tampa on 6/4/2016, 3:50 pm
I'm not sure. I tried to find out more about them, but they just got added to the model file on May 31st. I put them in their own group. I was going to group them with the BAM models, under "Trajectory and Beta Models" or maybe just "Trajectory Models", because they are at least similar. BAM models are trajectory too. They are even grouped together in the model file. I just couldn't decide what to group them under.



NHC model file:
http://www.nrlmry.navy.mil/atcf_web/docs/database/new/techlist.dat.nhc
Or:
http://ftp.nhc.noaa.gov/atcf/docs/nhc_techlist.dat



"Beta and Advection Model (BAM)

The Beta and Advection Model (BAM) refers to a class of simple trajectory models that utilize vertically averaged horizontal winds from the GFS to compute TC trajectories. These trajectories include a correction term to account for the impact of the earth.s rotation.  The BAM is based upon the concept of a simple relationship between storm intensity/depth and steering levels.  Strong cyclones typically extend through the entire depth of the troposphere and are steered by deeper layer-average winds, while weaker cyclones are steered by shallower layer-average winds.  The BAM is run in three versions corresponding to the different depths used in the trajectory calculation: BAM shallow (850-700 mb), BAM medium (850-400 mb), and BAM deep (850-200 mb), known as BAMS, BAMM and BAMD, respectively.  The performance of the BAM is strongly dependent on the dynamical input from the GFS.   A divergence of the three versions of the BAM indicates varying steering flow within the parent GFS model.  Hence, spread among the three versions of the BAM also serves as a rough estimate of the vertical shear as well as the complexity and uncertainty in the track forecast."

From: http://www.nhc.noaa.gov/modelsummary.shtml



There is also this is the model file:

KBMD - Beta and Advection model, deep (NHC-NCO PARA)
KBMM - Beta and Advection model, medium (NHC-NCO PARA)
KBMS - Beta and Advection model, shallow (NHC-NCO PARA)

And I don't know what "NHC-NCO PARA" is. It's probably National Hurricane Center - NCEP Central Operations Parallel.

Just based on something here as I tried to Google info about what it could be.

"Set to "test" during the initial testing phase, "para" when running in
parallel (on a schedule), and "prod" in production."

From: http://www.nco.ncep.noaa.gov/pmb/docs/Implementation%20Standards%20v10.0.pdf

Maybe related to different computers running it:
http://www.ncep.noaa.gov/newsletter/december2012/
(Weather and Climate Operational Supercomputing)



Unfortunately when you Google "Trajectory and Beta Model" only two results come up. The model listing at HurricaneCity and my site.

I thought about the grouping "Trajectory Models", and having all 6, but then you have:

TCLP
Trajectory CLIPER model 7-day

It's grouped between CLIPER and the trajectory models in the model file. If I had a group called "Trajectory Models", then I don't know whether to put TCLP with trajectory models or CLIPER. Then I also don't know whether there are other trajectory models. BAM is, but it doesn't say it in the model file. So maybe there are others too.

I could do "Trajectory and Beta Models". From the above it says:

"The Beta and Advection Model (BAM) refers to a class of simple trajectory models".

I didn't realize the plural there previously. I was not sure if Beta and Advection Model was one model with three parts or kind of three different models.

I think I will group them as:

Beta and Advection Models & Trajectory and Beta Models
Trajectory Models

For now.




More on BAM:



"Simplified Dynamical Track Models: Beta and Advection Models (BAMD, BAMM, BAMS)

These "Beta and Advection Models" (BAM) are simple trajectory models that only consider steering and the Beta-effect on TC motion. In these models, the TC cannot change nor have any impact on its environment.

The three-dimensional wind forecast from a more complex model is averaged in the vertical to create a two-dimensional wind field, the steering flow of the TC. The distinction between BAMD, BAMM, and BAMS is the depth of the layer over which the steering flow is calculated: Deep, Medium, or Shallow. This is the only way that variations in the vertical are incorporated into the BAM motion forecast. The choice of steering layer depends on the intensity of the TC being forecast (see schematic in Fig. 9.64).

One advantage of the BAM models is their speed. As of 2008, the BAM models run almost instantaneously and so the forecaster can create many forecasts of TC motion, varying the depth of the steering layer and the location of the TC (which can be in doubt, especially for weak systems with indeterminate eye structure). Thus, the forecaster can see how sensitive the forecast could be to these factors and get a sense of the potential for track errors in this situation (Fig. 9.66). Of course, these insights are limited by the lack of consideration of TC evolution and of vertical structure effects."

From: https://webcache.googleusercontent.com/search?q=cache:fdJ1YGzbSkIJ:https://www.meted.ucar.edu/tropical/textbook_2nd_edition/navmenu.php%3Ftab%3D10%26page%3D5.2.0+&cd=7&hl=en&ct=clnk&gl=us
Or register for free to view it says: https://www.meted.ucar.edu/training_module.php?id=950

A lot of interesting links here it appears:
http://www.wpc.ncep.noaa.gov/international/internal/DOCUMENTS/Comet_Training_Modules___MD__20151220.pdf
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