Cal Coop Ocean Fish Invest Lines/Stations¶
The CalCOFI pseudoprojection is the line and station coordinate system of the California Cooperative Oceanic Fisheries Investigations program, known as CalCOFI, for sampling offshore of the west coast of the U.S. and Mexico.
Classification 
Conformal cylindrical 
Available forms 
Forward and inverse, spherical and elliptical projection 
Defined area 
Only valid for the west coast of USA and Mexico 
Alias 
calcofi 
Domain 
2D 
Input type 
Geodetic coordinates 
Output type 
Projected coordinates 
The coordinate system is based on the Mercator projection with units rotated 30 degrees from the meridian so that they are oriented with the coastline of the Southern California Bight and Baja California. Lines increase from Northwest to Southeast. A unit of line is 12 nautical miles. Stations increase from inshore to offshore. A unit of station is equal to 4 nautical miles. The rotation point is located at line 80, station 60, or 34.15 degrees N, 121.15 degrees W, and is depicted by the red dot in the figure. By convention, the ellipsoid of Clarke 1866 is used to calculate CalCOFI coordinates.
The CalCOFI program is a joint research effort by the U.S. National Oceanic and Atmospheric Administration, University of California Scripps Oceanographic Institute, and California Department of Fish and Game. Surveys have been conducted for the CalCOFI program since 1951, creating one of the oldest and most scientifically valuable joint oceanographic and fisheries data sets in the world. The CalCOFI line and station coordinate system is now used by several other programs including the Investigaciones Mexicanas de la Corriente de California (IMECOCAL) program offshore of Baja California. The figure depicts some commonly sampled locations from line 40 to line 156.7 and offshore to station 120. Blue numbers indicate line (bottom) or station (left) numbers along the grid. Note that lines spaced at approximate 31/3 intervals are commonly sampled, e.g., lines 43.3 and 46.7.
Usage¶
A typical forward CalCOFI projection would be from lon/lat coordinates on the Clark 1866 ellipsoid. For example:
proj +proj=calcofi +ellps=clrk66 E <<EOF
121.15 34.15
EOF
Output of the above command:
121.15 34.15 80.00 60.00
The reverse projection from line/station coordinates to lon/lat would be entered as:
proj +proj=calcofi +ellps=clrk66 I E f "%.2f" <<EOF
80.0 60.0
EOF
Output of the above command:
80.0 60.0 121.15 34.15
Options¶
Note
All options are optional for the CalCOFI projection.

+R
=<value>
¶ Radius of the sphere given in meters. If used in conjunction with
+ellps
+R
takes precedence.
Mathematical definition¶
The algorithm used to make conversions is described in [EberHewitt1979] with a few corrections reported in [WeberMoore2013].