More exploration of SST fronts (near-surface plots) (sixcharmi data)

• These examples focus on times of largescale background SST gradients.
  Also see an earlier version based on realtime data
  There is some overlap. T and S are virtually the same as before, some differences in corrected (u,v).

• These background gradients are shown in month-by-month GHRSST maps with glider tracks overlaid.

• Note that T and S are shown to 200m, crosstrack ug is shown to 500m (to see shear).
• Cyan ticks in salinity panel show glider dives.
• Green bullets above salinity plot show 12-hour intervals (relate to tides).