High clouds have limited the satellite coverage for this weekend. The few windows between the clouds hint at the continued advection of the phytoplankton bloom in offshore waters. The near-shore area has poor satellite coverage where the main bloom has resided the last month (note the chlorophyll image is for Sunday September 4th) and the imagery today was even less useful. The one day average SST for the Northeast, shows warm temperatures in the Mid-Atlantic with upwelling in the north and the passage of warm core rings offshore the shelf associated with Gulf Stream meanders. In the Mid-Atlantic the CODAR (25 hour average) shows strong offshore transport along much of the New Jersey coast which is consistent with persistent upwelling (though it is not readily evident in the SST) and the continued offshore transport of the coastal bloom.
We have two gliders transecting the shelf. One is the continuing mission for the EPA/NJ DEP/Rutgers. This glider, for those not following over the last month is outfitted with CTD and oxygen sensor. Since the passage of Irene a week ago the glider has been directed to conduct short cross shore transects to monitor the status of the oxygen. The glider has been heading inshore the last few days. The glider shows strong stratification despite the passage of a category I hurricane just 7 days ago. Since the storm the surface waters appear to warming, however nearshore the waters appear to be upwelling cold bottom water to near the surface. This is consistent with the strong transport seen in the CODAR imagery. The upwelling is also seen as the uplift of high salinity bottom water observed in the last day of Ru16 data. We would benefit from a clear satellite image, however we are expected to have storms and rain for the next few days so we will have to rely on glider data. Oxygen and %oxygen saturation remains low in the bottom waters, with values low enough to warrant more monitoring to assess the status of the of the shelf.
A second glider ru15 was deployed and is making a cross shore transect across the shelf. This glider is outfitted with CTD and a WetLabs EcoPucks which give us proxy measurements for particles, phytoplankton and colored dissolved organic matter (CDOM). The glider, like ru16, shows strong stratification in the offshore waters, and while the coldest waters remain offshore below the thermocline, there are hints of upwelling isopycnals in the temperature and salinity data in the nearshore waters. The nearshore waters show lower salinity concentrations which reflects the historic river runoff from the New Jersey watersheds over the last week. The third plot below shows the optical proxy for particles. Particle concentrations are enhanced in the bottom waters and in nearshore waters. In contrast the chlorophyll concentrations are low in the offshore waters but are highest at the thermocline and in the inner shelf. The high concentrations on the inner shelf corroborates the satellite imagery of the last week. The CDOM data show patterns similar to the particle concentrations and the very high values in the nearshore waters reflect the combined contributions between the river outflow and the phytoplankton exudates.