The cells of the CalCOFI grid. 113 station cells: the Voronoi tessellation of the official
station positions (cc_station_positions), confined to the cells of the previous grid
(cc_grid_v1) it replaces, so an outer station's cell stops where the previous grid stopped.
And 112 kept cells: the previous grid's cells beyond 20 nautical miles of the official
pattern, with their own boundaries and keys, so a historical position keys as it always did.
Both end at the coastline (cc_grid_land). Every station cell holds its own station, and the
release's grid table is these cells (calcofi4db::build_grid_reference()). Built by
cc_grid_build() in data-raw/cc_grid.R; the rules are documented there.
Format
An sf of 225 cells (EPSG:4326) with
- grid_key
the release key,
st{station}-ln{line}, with_histfor a cell of the historical pattern (e.g.st26.7-ln93.3,st120-ln110_hist)- sta_key
station key in the form "
line,station" (e.g."93.3,26.7")- sta_lin
line (alongshore) in the CalCOFI coordinate system (double:
76.7,93.4)- sta_pos
station (offshore position) in the CalCOFI coordinate system (double:
26.7)- sta_dpos
nominal spacing class in station units: 5 (nearshore), 10 (offshore) or 20 (historical pattern)
- sta_shore
"nearshore" (station 60 or less) or "offshore"
- sta_pattern
"standard" (lines 76.7 and south: the 75-station pattern), "extended" (lines north of 76.7) or "historical" (kept from the previous grid)
- zone_key
"{sta_shore}-{sta_pattern}", the key of cc_grid_zones- sta_type
the station's type on the official list: "ROS" (rosette) or "SCCOOS" (the nine ~20 m inshore stations);
NAfor a cell kept from the previous grid- sta_source
"official" (a station of the official list) or "previous" (a cell kept from cc_grid_v1)
- geom
the cell (EPSG:4326); edges are straight in longitude/latitude. A station cell is one polygon (but
st53-ln60, which keeps 21 km2 of Tomales Bay that no station cell reaches by water); a kept cell is the previous cell, in as many pieces as it was (13 are in several)
Source
Station Positions - CalCOFI; coastline (c) OpenStreetMap contributors (ODbL)
Details
Before this grid, cells were Voronoi polygons of an idealized lattice and an inshore cell held
several real stations (cc_grid_v1). 84 of the 113 station cells reuse a key whose polygon
changed, so never map a key between the two grids by name: use the release's grid_crosswalk
table (calcofi4db::build_grid_crosswalk()), and cc_grid_key() to key a position.