PWSSC data

I have uploaded the first PWSSC drifter files. Usually, they would cover 6pm - 6pm, but since they went in yesterday afternoon I just dumped everything we had up until about 10am this morning.

The GPS positions on the 10m SVPs are not looking good, so I used the ARGOS positions instead. These have a larger error, and are measured less frequently than every half hour. I still gridded to 1/2 hour, though. There is a little one-liner readme in the svp directory that says exactly this.

I will update this directory with the usual 24 hr report at 6pm tonight.