Fort.200: Multiple File Meteorological Forcing Input

The Multiple File Meteorological Forcing Input is used when GFS (NWS=10) or Eta29 (NWS=11) is specified in the Model Parameter and Periodic Boundary Condition File. These files provide wind velocity and atmospheric pressure data for the simulation.

File Structure

The basic file structure varies depending on the NWS value:

For NWS = 10 or 110:

for k=1, LONB * LATB
    PG(k), UG(k), VG(k)
end k loop

For NWS = 11 or 111:

for k=1, 8
    IYEAR, IMONTH, IDAY, IHOUR
    for j=1, LONB * LATB
        UE(j), VE(j), PE(j)
    end j loop
end k loop

GFS (NWS=10) Notes

• Meteorological data is input to a T1534, Gaussian grid (NWLON*NWLAT = 3072*1536 = 4,718,592)

• Data is interpolated in space onto the ADCIRC mesh

• Data are ordered in these files the same way they are generated by the degribbing program

• Files are named sequentially: fort.200, fort.200+N, fort.200+2*N, etc. - N = WTIMINC/3600 (time interval in hours between data files) - WTIMINC must be evenly divisible by 3600

• For cold starts: - Winds are assumed at rest at TIME=STATIM - First data file (fort.200+N) corresponds to TIME=STATIM+WTIMINC

• For hot starts: - Initial file (fort.200) required at TIME=HOT START TIME

• Data is interpolated in time to the ADCIRC time step

• Units: - Wind velocity (@ 10m): m/s - Surface pressure: Pascals (N/m²)

Wind Stress Calculation (NWS=10):

WIND_SPEED = magnitude of WIND_VEL
DRAG_COEFF = 0.001*(0.75+0.067*WIND_SPEED)
If (DRAG_COEFF.gt.0.003) DRAG_COEFF=0.003
WIND_STRESS = DRAG_COEFF*0.001293*WIND_VEL*WIND_SPEED

Pressure Conversion:

PRESSURE{m H2O} = PRESSURE{Pascal}/(GRAVITY*DENSITY of H2O)

Eta-29 (NWS=11) Notes

• Meteorological data is input to the standard Eta-29 “E” grid (NWLON*NWLAT = 181*271 = 49,051)

• ADCIRC grid must be in lon, lat coordinates

• Files are named sequentially: fort.200, fort.201, fort.202, etc.

• Each file contains 8 data sets spaced 3 hours apart (WTIMINC = 10800 sec)

• Data sets correspond to 03:00 to 24:00 hours on the day of the file

• For cold starts: - Winds are assumed at rest at TIME=STATIM - First data set in fort.201 corresponds to TIME=STATIM+WTIMINC

• For hot starts: - Initial file (fort.200) required with last data set at TIME=HOT START TIME

• File type: binary (ACCESS=’sequential’, FORM=’unformatted’)

• Units: - Wind velocity (@ 10m): m/s (E grid coordinate directions) - Surface pressure: millibars

Wind Stress Calculation (NWS=11):

WIND_SPEED = magnitude of WIND_VEL
DRAG_COEFF = 0.001*(0.75+0.067*WIND_SPEED)
If (DRAG_COEFF.gt.0.003) DRAG_COEFF=0.003
WIND_STRESS = DRAG_COEFF*0.001293*WIND_VEL*WIND_SPEED

Pressure Conversion:

PRESSURE{m H2O} = PRESSURE{millibars}/(100*GRAVITY*DENSITY of H2O)

General Notes

• Meteorological data must be provided for the entire model run, otherwise the run will crash

• IYEAR, IMONTH, IDAY, IHOUR values are read but ignored by ADCIRC

• Data is interpolated in time to the ADCIRC time step

• For NWS=11, each file contains 8 data sets for a total of 1 day of data per file

• The first and last data sets in each NWS=11 file correspond to 03:00 hrs and 24:00 hrs, respectively

• For NWS=11, 8 sets of meteorological data must be provided every WTIMINC in each file

• For NWS=11, appropriately named files must be provided for each day of the model run