Documentation for the University of Wisconsin-Nonhydrostatic Mesoscale Model (UW-NMS), v7b

Summary

Model type:	Dynamical – full physics, track and intensity
Model timeliness:	Late model
Model status:	Experimental, Quasi-Operational (HFIP Stream 1.5)
Basins run in:	Atlantic, Eastern Pacific
ATCF TECH identifier:	Deterministic run(s): UWN4, UWN5
Forecast period:	0 to 126 hours
Included in TCGP:	Yes
Domain:	81º x 60º (outer, 45km spacing), 5.8º x 5.8º (inner, 4.1 km spacing)
Vertical coordinate:	Geopotential height
Grid:	Arakawa C grid (Rotated Spherical Geometry)
Cumulus parameterization:	Varies (none or modified Emanuel)
Microphysics parameterization:	Tripoli-Flatau (1 liquid, 2 ice categories)
Boundary layer parameterization:	1.5 level TKE closure
Radiation parameterization:	RRTM LW and SW
Ocean coupling:	1.5-layer
Initialization method:	Rankine vortex nudged to TCVITALS 12-hours prior to initial time
Initial and boundary conditions:	GFS fields; FNMOC analyzed SST; mixed layer depth and sub-mixed layer thermal stratification from Levitus 0.25º monthly climatology (Levitus 1994)
Primary contact:	Professor Greg Tripoli, University of Wisconsin-Madison (UW)
Model website:	http://cup.aos.wisc.edu/will/HFIP/
Full documentation:	http://mocha.meteor.wisc.edu/uw-nms.html
Ensemble products:	http://cup.aos.wisc.edu/will/HFIP/ens.html

Brief Technical Description

The University of Wisconsin Nonhydrostatic Modeling System is a fully-scalable, nonhydrostatic regional model designed to simulate scale interation via a potential-enstrophy conserving dynamical core. For hurricane forecast applications in 2013, a unique downscaling method is applied to the outermost grid whereby the model solution is forced toward the GFS solution at distances greater than 1,000 km from the TC center. This allows an optimal allocation of resources at the regional scale (i.e. a focus on the TC structure and intensity) while allowing the governing global model (in this case, the GFS) to have a greater influence on track.

Initialization Method

12 hours prior to the intended initialization, a Rankine vortex with the size and intensity characteristics specified in the TCVITALS is inserted into the model. Over the course of the next 12 hours, the model is nudged toward the wind and temperature fields consistent with the TCVITALS vortex, thus allowing the forecast to begin with a model TC that has the appropriate size and intensity and which is largely free from the spin-up issues known to plague bogus initializations.

References

Tripoli, G. J., 1992: A Nonhydrostatic Mesoscale Model Designed to Simulate Scale Interaction. Mon. Wea. Rev., 120, 1342-1359.

 

 

The information on this page was provided by William Lewis (UW-Madison) on 05 June 2013.