SAFDE - Origins for the OI Mapping and for Section Plots
Chris Meinen's Suggestions


Origin of the SAFDE array
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In order to optimally interpolate (OI) the IES and HEF data it's necessary to choose an origin upon which to center the x-y coordinate system. (An x-y coordinate system is necessary, rather than a Lat-Lon coordinate system, because the correlation length scales used in the mapping are in kilometers.)

Based on our conversations to date, the origin which will be used is

Latitude: 51.0 S
Longitude: 143.5 N

Furthermore, all conversions between distance and degrees should be done using cos(51 deg), rather than the local latitude, in order to maintain consistency.


Origin along each mooring line
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When vertical sections of the SAFDE data are plotted, whether it's temperature, salinity, or velocity, these sections will generally be plotted along one of the three lines of moorings (the two IES lines or the HEF line). Since the mooring lines don't run north-south or east-west, neither latitude nor longitude can be used as the abscissae on these plots; distance will have to be used. As such, a geographic origin must be defined on each of the three mooring lines in a manner which is consistent from one line to the next.

Chris' suggested solution is to draw a line perpendicular to all of the mooring lines which passes through the OI grid origin listed above. Such a line has been calculated and the lat-lon coordinates of the intersections with the three mooring lines are as follows:

Western IES line origin--
Latitude: 50.9588 S
Longitude: 143.2700 E

Central HEF line origin--
Latitude: 51.0210 S
Longitude: 143.6200 E

Eastern IES line origin--
Latitude: 51.1022 S
Longitude: 143.9800 E

Please let everyone know if you have alternate suggestions.


Last Revised: 30 November 2000