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Longitude,Latitude to i,j Converter Print

This tool converts longitude,latitude values to HYCOM i,j values. The tool hycom_lonlat2ij in the HYCOM source distribution requires one latitude value, one longitude value, and the respective grid.a file for the HYCOM model you are working with.

hycom_lonlat2ij - Usage:

hycom_lonlat2ij lon lat [grid.a]
hycom_lonlat2ij [grid.a] < lonlat.txt

Prints the nearest HYCOM p-grid point to lon,lat. A single lon,lat can be specified on the command line, or a sequence of lon,lat pairs can be input from stdin. grid.a is a hycom grid file, default regional.grid.a. Note that the corresponding grid.b must also exist. This version for "serial" Unix systems. Written by Alan J. Wallcraft, Naval Research Laboratory, November 2001.

hycom_latlon2ij is in the 2.2.18_ALL.tar.gz bundle, from hycom/ALL/bin/hycom_lonlat2ij.F:

C  hycom_lonlat2ij - Usage:  hycom_lonlat2ij lon lat [grid.a]
C                            hycom_lonlat2ij [grid.a] < lonlat.txt
C
C  hycom_lonlat2ij_area - Usage:  hycom_lonlat2ij_area lon lat [grid.a]
C                                 hycom_lonlat2ij_area [grid.a] < lonlat.txt
C
C     Prints the nearest HYCOM p-grid point to lon,lat.
C     The _area varient adds grid point's cell area and cell area statistics
C
C     A single lon,lat can be specified on the command line,
C     or a sequence of lon,lat pairs can be input from stdin.
C
C  grid.a is a hycom grid file, default regional.grid.a.
C  Note that the corresponding grid.b must also exist.

In the rectilinear part of the grid (south of 47N) i is independent of latitude and j is independent of longitude:

ajax 189> hycom_lonlat2ij 90 0
  199 1505
ajax 190> hycom_lonlat2ij 90 30
  199 1898
ajax 191> hycom_lonlat2ij 0 30
 3574 1898

North of 47N this isn't the case:

ajax 192> hycom_lonlat2ij 90 70
  552 3084
ajax 193> hycom_lonlat2ij 90 80
  825 3206
ajax 194>  hycom_lonlat2ij 0 80
 3459 2995

 

Disclaimer

This is a demonstration product from the HYCOM Consortium and is provided as is. HYCOM Consortium does not warrant or suggest that this data is fit for any particular purpose. Further, neither COAPS nor HYCOM consortium guarantee availability, service updates or timely data delivery.