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