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NWS

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NWS is a parameter in the fort.15 file that selects the meteorological forcing input type. The value on the "NWS line" of the fort.15 file also implicitly includes other parameters affecting wave coupling and ice inputs. Further, NWS affects not just the file type and handling of meteorological data, but also changes what the meteorological parameter line (informally, the WTIMINC line) looks like in the fort.15 file. See the supplemental meteorological/wave/ice parameters page for information on the format of this line.

ADCIRC supports a wide range of meteorological input formats, including moving/fixed gridded data in several file formats, tropical cyclone track and parameter data that can be turned into wind/pressure fields via one of several internal vortex models, and direct specification of wind speeds or stresses on nodes. As a result of the great flexibility and importance of this choice, several pages are devoted to the topic. In particular, see also the fort.22 file and wind stress pages.

Value Seen in fort.15 File

In the fort.15 file, what we call "NWS" is actually a combination of several parameters. For example, given a 5-digit value on that line,

-12305                    ! TRICKY NWS IMPOSTER

the first two digits (ten-thousands and thousands) tell us the format of ice data NCICE=12, the 3rd digit (hundreds) tells us the wave coupling mode NRS=3, and the last two digits (tens and ones) combined with the sign of the entire value tell us the meteorological forcing mode NWS=-5. If the value has only 3 digits then ADCIRC assumes no ice input NCICE=0, and if it's 2 digits then ADCIRC further assumes no wave coupling NRS=0. It is often presumed that when one refers to "NWS", one is referring to the 2-digit value, not what is in the fort.15 file, but be mindful of the ambiguity here.

Parameter Summary

The following table is a summary of possible NWS values, their descriptions, and associated meteorological input files (required and optional).

NWS Value Short-name Description Required Input Files Optional Input Files
1 Wind stress, every node, every timestep Wind stress and atmospheric pressure are read in at all grid nodes at every model time step from the fort.22 file fort.22
2 Wind stress, every node, every WTIMINC Wind stress and atmospheric pressure are read in at all grid nodes at a time interval that does not equal the model time step from the fort.22 file. Interpolation in time is used to synchronize the wind and pressure information with the model time step. The wind time interval (WTIMINC) is specified in the fort.15 file. fort.22
3 US Navy Fleet Numeric Wind velocity is read in from a wind file from the fort.22 file in US Navy Fleet Numeric format. This information is interpolated in space onto the ADCIRC grid and in time to synchronize the wind and pressure information with the model time step. Garret’s formula is used to compute wind stress from the wind velocity. Several parameters describing the Fleet Numeric wind file must be specified in the fort.15 file. fort.22
4 PBL/JAG Wind velocity and atmospheric pressure are read in (PBL/JAG format) at selected ADCIRC grid nodes from the fort.22 file. Interpolation in time is used to synchronize the wind and pressure information with the model time step. Garret’s formula is used to compute wind stress from wind velocity. fort.22
5 Wind velocity, every node, every WTIMINC Wind velocity and atmospheric pressure are read in at all grid nodes from the fort.22 File. Interpolation in time is used to synchronize the wind and pressure information with the model time step. Garret’s formula is used to compute wind stress from wind velocity. fort.22
6 wind velocity, rectangular grid, every WTIMINC Meteorological data (U,V,P) is input on a rectangular grid (either in Longitude, Latitude or Cartesian coordinates, consistent with the grid coordinates) and interpolated in space onto the ADCIRC grid. Wind velocity (U,V @ 10 m above the water surface) must be input in units of m/s and surface atmospheric pressure (P) must be input in units of Pascals = Newtons/square meter. The meteorological grid MUST cover the entire ADCIRC mesh; that is, the ADCIRC mesh must be ENTIRELY within the meteorological grid or an error will result. fort.22
7
ADCIRC version: = future
Wind stress, regular grid, every WTIMINC Surface stress and pressure values are read in on a regular grid from the fort.22 file. Currently, this feature is not supported for parallel runs because adcprep cannot decompose the files. See [1]. fort.22
8 Symmetric Holland Vortex Wind velocity and atmospheric pressure are calculated at every node on the fly by ADCIRC internally using the Dynamic Holland model. fort.22
10 NCDC GFS Wind velocity (10 m) and atmospheric pressure are read in from a sequence of National Weather Service (NWS) Aviation (AVN) model output files. Each AVN file is assumed to contain data on a Gaussian longitude, latitude grid at a single time. fort.200, fort.200+N, fort.200+2*N, fort.200+3*N,…., where N is the time interval (in hours) between successive meteorological data
11 National Weather Service Eta-29 file Wind velocity (10 m) and atmospheric pressure are read in from a sequence of stripped down National Weather Service (NWS) ETA 29km model output files fort.200, fort.201, fort.202, fort.203,….,
12 / -12 OWI ASCII, every WTIMINC See NWS12 for details. Wind velocities (U10, V10) and atmospheric sea level pressure (SLP) are provided in the OWI ASCII format on one to three rectangular (lat/lon) grid(s) fort.22, fort.221, fort.222 fort.223, fort.224, fort.217, fort.218
13
ADCIRC version: 55
OWI NetCDF See NWS13 for details. Wind velocities (U10, V10) and atmospheric sea level pressure (SLP) fields are provided in the OWI NetCDF format as 1 or more meshgrid overlays stored in netCDF groups, supporting storm following grids on overlay 2 and on. default is fort.22.nc, see NWS13
14 / -14
ADCIRC version: 55
GRIB2/NetCDF Binary, every WTIMINC Gridded data of wind velocities (U10, V10) and atmospheric sea level pressure (SLP) are provided in GRIB2 (e.g., GFS, CFSv2) or NetCDF (e.g., ERA5, WRF) binary files. Gridded data may be on a standard rectangular lat/lon grid, a Gaussian grid, or a projected WRF-like grid. Requires that ADCIRC is compiled with DATETIME, NetCDF and if required, GRIB2 flags enabled (the static libraries must be compiled). Will find and read time-snaps based on the reference date, NCDATE located near or at the bottom of the fort.15 file taking into account hot-start times etc. If the negative value is used, OWI ASCII (see NWS = 12) meteorology will overwrite the GRIB2/NetCDF meteorology data in the overlap region (except during the "skipping OWI time snap" phase). fort.221.grb2, fort.222.grb2
or
fort.22, fort.221.nc, fort.222.nc
15 HWIND Uses data assimilated snapshots of the wind velocity fields of tropical cyclones that are produced by the NOAA Hurricane Research Division (HRD) fort.22 Additional HWIND files specified in the fort.22 file
16 GFDL GFDL model output files produced by the Geophysical Fluid Dynamics Laboratory at NOAA. Each ASCII GFDL model output file contains one or more nested grid dataset where the nested grids are allowed to change in time. Coarse grid data is not stored where finer nest data is given. fort.22 Additional GFDL files specified in the fort.22 file
19 Dynamic Asymmetric Model[note 1] Wind velocity and atmospheric pressure are calculated at exact finite element mesh node locations and directly coupled to ADCIRC at every time step using the asymmetric hurricane vortex formulation based on the Holland gradient wind model. The input file is assumed to correspond to the ATCF Best Track/Objective Aid/Wind Radii Format. This option uses the radii at specific wind speeds (34, 50, 64, 100 knots) reported in the four quadrants (NE, SE, SW, NW) of the storm to calculate the radius of maximum winds as a function of the azimuthal angle. Garret’s formula is used to compute wind stress from the wind velocity. This option allows the user to set a value for Rmax and Holland B Parameter. Additionally the user can select the isotachs to be used for each of the 4 quadrants. The utility program aswip_1.0.3.F located in the /wind folder will generate the NWS=19 formatted file from a NWS=9 formatted fort.22 input file. fort.22
20 Generalized Asymmetric Holland Model The Generalized Asymmetric Holland Model (GAHM) provides a set of theoretical and practical improvements over previous parametric meteorological vortex models in ADCIRC. The track file format is similar to that of the older Dynamic Asymmetric Model (NWS = 19) but with 8 additional columns of data. fort.22

Extended NWS with Ice + Waves

The following presents a summary of the extended NWS values to included ice-coverage and/or wind wave-coupling

Meteorological Data Format Met. Only Met. plus Waves from fort.23 Met. plus Waves SWAN Met. plus Waves STWAVE Met. plus Ice Coverage, Waves off Met. plus Ice Coverage OWI-like format plus Waves from fort.23 Met. plus Ice Coverage OWI-like format plus Waves from SWAN Met. plus Ice Coverage OWI-like format plus Waves from STWAVE
none 0 n/a n/a n/a n/a n/a n/a
wind stress, every node, every timestep 1 101 301 401 12101 12301 12401
wind stress, every node, every WTIMINC 2 102 302 402 12102 12302 12402
US Navy Fleet Numeric 3 103 303 403 12103 12303 12403
PBL/JAG 4 104 304 404 12104 12304 12404
wind velocity, every node, every WTIMINC 5 105 305 405 12105 12305 12405
wind velocity, rectangular grid, every WTIMINC 6 106 306 406 12106 12306 12406
wind stress, regular grid, every WTIMINC 7 107 307 407 12107 12307 12407
symmetrc vortex model 8 108 308 408 12108 12308 12408
asymmetric vortex model (no longer available) n/a n/a n/a n/a n/a n/a n/a n/a
National Weather Service AVN 10 110 310 410 10010 (ice in 4th column of AVN file) 12110 12310 12410
National Weather Service ETA 29km 11 111 311 411 12111 12311 12411
Oceanweather Inc (OWI) 12 112 312 412 12112 12312 12412
Oceanweather Inc (OWI) NetCDF 13 113? 313? 413? 12113? 12313? 12413?
GRIB2/NetCDF 14 114 314 414 14014 (GRIB2/NetCDF format ice) 14114 (GRIB2/NetCDF format ice) 14314 (GRIB2/NetCDF format ice) 14414 (GRIB2/NetCDF format ice)
H*Wind 15 115 315 415 12115 12315 12415
Dynamic Asymmetric Holland Model[note 1] 19 119 319 419 12119 12319 12419
Generalized Asymmetric Holland Model 20 120 320 420 12120 12320 12420

Notes

  1. 1.0 1.1 Use of this is discouraged.