Southwesterly winds associated with the summertime Bermuda high pressure system result
in coastal upwelling along the southern New Jersey coast.
While the wind forcing is present, warm surface water is transported offshore and an
initially narrow band of cold, upwelled water forms a series of three recurrent upwelling
centers on the downstream side of topographic highs associated with ancient river deltas.
The recurrent upwelling centers are found to be the preferred
locations for phytoplankton blooms, and are co-located with historically observed regions
of low dissolved oxygen. When the wind forcing relaxes, the warm water also begins to
relax back toward the coast. The warm water that was closest to the coast (in between the
upwelling centers) reaches the shore first, and then turns south, propagating alongshore
as a buoyant plume should As this buoyant plume races south, it cuts off the cold water in
the upwelling centers as isolated eddies.
The general forecasting and observational strategy centers around a 3-day forecast that
is run twice per week. Real-time assimilation data will include satellite SST, CODAR
derived surface currents, LEO-15 subsurface CTD and ADCP profiles, and adaptive sampling
datasets from our survey vessel and the REMUS autonomous underwater vehicles. Assuming it
takes close to 24 hours for the model to assimilate data up to the present and then run an
additional 3-day forecast, model predictions will be available at the end of forecast day
1. The model forecasts and additional real-time data will then be used to establish
shipboard and AUV sampling patterns for forecast days 2 & 3. We propose to fix the
survey pattern for 2 days to allow us to resolve the inertial oscillations over two 19
hour inertial periods.
The initial survey pattern to collect subsurface assimilation data will consist of one or
two cross-shelf lines approximately 20 km long optimally oriented to resolve the desired
features over the last 2 days of each forecast cycle. The survey line(s) will be occupied
by the Caleta for 12 daylight hours each day for 2 consecutive days. As the REMUS vehicles
come on line, we will expand our operating range by using the REMUS to take over patrol
duties on the central line. Initial REMUS runs on rechargeable batteries will be about 3
hours in duration, freeing up the Caleta mid-day to occupy northern and/or southern lines.
Long-duration REMUS test runs on lithium batteries later in the month may free up the
Caleta for the entire day. In the latter case, proposed survey patterns include the spokes
of a wheel centered on the upwelling center, or having the REMUS patrol the upwelling
center while the Caleta surveys the southward flowing coastal jet.
Two additional survey vessels will be operated during the experiment. The Northstar will conduct bio-optical surveys nominally 4 days per week matched to the Caleta physical surveys. The Northstar 6 will carry the turbulence REMUS support crew to conduct detailed turbulence surveys in critical locations nominally once per forecast cycle.
The scheduled 3-day forecast time periods are (a) Sunday-Tuesday and (b)
Wednesday-Friday.
This places the scheduled shipboard and AUV survey cruises on (a) Monday and Tuesday and
(b) Thursday and Friday.
Wednesday and Saturday are available for weather days, new equipment tests and
maintenance. The experiment will be conducted for 4 weeks beginning July 6.