[THREDDS #QLQ-406940]: Bug extracting surface velocity data from NCSS

Hi Rich,

I was able to get this down to a minimal test case by using only the variable 
'pn' and 'u':
http://geoport-dev.whoi.edu/thredds/ncss/coawst_4/use/fmrc/coawst_4_use_best.ncd?var=pn&var=u&north=48.4639&west=-101.7498&east=-53.2530&south=11.8884&horizStride=1&time=2016-01-29T00%3A00%3A00Z&vertCoord=15&addLatLon=true&accept=netcdf

What's happening here is that 'u' has a vertical coordinate equal to 's_rho' 
and 'pn' has a vertical coordinate equal to 'null'. So *technically* the error 
message is correct. Whether it makes sense to reject such a query is another 
matter, of course.

It would be interesting to test this again on 5.0. All of the GeoGrid stuff got 
replaced with GridCoverage, so it may not be an issue any more. If nothing 
else, I wouldn't want to attempt to fix this on 4.6 when the code has changed 
so drastically in 5.0.

The vertical level is coordinate-based, like everything else in NCSS. Just 
enter the value you want; don't worry about the index underneath.

-Christian

Ticket Details
===================
Ticket ID: QLQ-406940
Department: Support THREDDS
Priority: Normal
Status: Closed