Sorry for the lack of communication, but as everyone else the schedule has been intense. So a quick update tonight. The weather has been variable with hot temperatures resulting in a profusion of green buds bursting on our trees. So what has been happening on our ocean. Tonight we will focus on the satellite and CODAR data from my last update, but a quick kudos to Matt Oliver for filling the void in tardy postings.
So what have we seen in the last few weeks. As reminder we have seen the highest temperatures this last winter on the Mid-Atlantic, but the SST data since early April do not show significant warming on the shelf. The main features that are evident in the daily averaged SST data is the passage of the offshore warm core rings to the north as they peel off the Gulf Stream.
This raises the question, as to why the given the many recent spates of unseasonably hot weather we not seen significant warming in the SST images? We have had warm periods but they have been combined with periods of reasonably high high winds, which to a certain extent has offset the surface warming by mixing cold bottom waters to the surface. The wind records below were recorded from the National Marine Sanctuaries (Jacques Costeau Reserve in Tuckerton, NJ) and it shows a number of wind events in excess of 5 m/s, nasty conditions if at sea. Thus while it has been warm, our current hypothesis is that the wind resulted in the entrainment of cold bottom water to the surface, which is why the SST images may not be showing an increase.
The variable winds were visible in the HF radar surface current data. An examination over the last few weeks below show the spatially variable surface currents with the periods of high currents (the light blue to red colors) that are coincident with the high winds. We will begin a more comprehensive analysis of the correlations between the wind forcing and the surface current response.
What is the biological status of the shelf? Below is the ocean color imagery (of which there has been little due to clouds, aerosols, and misbehaved satellites), but below is a nice image from April 13 2012. The image is from the US MODIS Aqua satellite. It shows nearshore and offshore phytoplankton blooms. The larger image of the northeast nicely shows the offshore prototypical spring bloom at the shelf edge, which is a critical event for the offshore migratory fish that move along the continental slope as all good tuna fishermen know. We will better compile the historical data in the coming week and try to answer whether the spring bloom is earlier this year compared to past years given the warm winter.
