September 5 update, a cloudy Labor Day

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.

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Rain Rain Go Away

Below is a post provided by our Federal Partners at NOAA.  The NEFSC Behavioral Ecology Branch in Sandy Hook, NJ has been sampling the ocean off Northern New Jersey before and after Hurricane Irene.  The post below was submitted by Dr. John Manderson after an early morning sampling run.

Where on earth did the ocean go? Or what is the estuary doing in the ocean?

The upwelling area off Tuckerton is very well sampled by Rutgers Robot gliders. But the ocean off the mouth of Hudson Raritan Estuary is also interesting. This morning the NOAA ECOS program which operates out of Sandy Hook measured hydrography and took some samples for nutrients off the mouth of the Hudson River.

Our plan was to do 20 stations to the Hudson Shelf Valley which we mapped out early this morning on the Stevens NYHOPS.  We know NYHOPS is good but we thought “there is no way the salinities in the ocean are that low”.  Actually the salinities were lower.  We got to many of the stations and had some data collected August 17 on a similar transect with which we could compare.

As background, below are some of the meteorological data measured at the Ambrose buoy (NOAA buoy 44065) just off the mouth of the Hudson Raritan estuary. The red lines in the two panels show August 12, the last date ECOS sampled the New Jersey transect, and today, September 2. The dips in atmospheric pressure and seawater temperature, and increases in wave height and winds speed associated with the passage of IRENE are clearly visible in the plots

Below are the locations of ECOS plankton sampling stations on Aug 17 superimposed on the MARACOOS NHOPs model output for Salinity.  We took water column profiles at these 5 and an additional 13 stations that day.

Here are the temperature and salinity combinations for today and for August 17.  The colors indicate chlorophyll values were as high as 20 mg liter today (This could be chlorophyll as well as other colored organic matter).  The symbols are sized by depth.  Salinity in the upper few meters of the water column was <21 PSU all the way out to the Hudson shelf valley.  NOAA is not sure their CTD probe which measures water column properties reached the bottom today because of extremely high bottom current velocities.

The mode of surface salinity today was ~21 PSU which is lower than we often measured relatively high up in the estuarine tributaries during the summer.Finally here are the oxygen and chlorophyll values measured on Aug 17 and Sept 2 along the transect.  The chlorophyll values are pretty extreme today and minimum dissolved oxygen measurements are lower than in August but still above 3 mg per liters (dotted red line).

NOAA ECOS will continue sampling next week using acoustic instruments as well as CTD probes.  These instruments will allow us to monitor the effects of Irene and the summer bloom on the distribution of various sizes of organisms, as well as water column properties in the coastal ocean outside the mouth of the Hudson River.

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Post-Storm Bloom Conditions – An Initial Look

Three days after the storm, glider RU16 completed its transect back across the shelf toward the beach.    This section gives us our first complete look at how the inner-shelf was impacted by Hurricane Irene.   For the past week the glider has gone back and forth three times, two before the storm and one after.

The satellite image from the day after Irene shows that the bloom off the south Jersey is now pushed more evenly along the coast.   Also, the highest concentration of cells do not extend as far offshore as what we saw before the storm.

Now we look to the glider to see how the altered surface expression of the bloom extends down into the water column.   One of Irene’s more dramatic impacts in the data is seen in the temperature fields.   We can see a  significant cooling throughout the surface layer with a fully mixed water column in water shallower than 20m (below left).   The timing of the storm is shown as a red dashed line.

For the dissolved oxygen impacts we see a similar mixing in the surface layer.   As the glider made its way inshore underneath the higher cell concentrations seen in the satellite image above, the dissolved oxygen in the surface layer increases.   We also see the the deeper mixed layer is allowing higher oxygen concentration to penetrate closer to the seafloor

Pre-Storm

Post Storm

The distribution of oxygen values in the pre-storm and post-storm sections (above) shows a shift toward the middle of the range.  After the storm there are no observed concentrations below 4 mg/L or above 8 mg/L.  There is still a bi-modal distribution but it is now centered over about 5.2 mg/L and 6.5 mg/L for the bottom and surface layers respectively.   The largest peak in the distribution has also shifted from the lower concentrations of the bottom layer to the higher concentrations of the surface layer.  RU16 will now continue to monitor conditions along this line until it is recovered later next week.

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Glider update for August 31

A quick update of the gliders. As I type we believe that the floating glider RU23 has been recovered. the glider recovery is being coordinated by Chip who has is receiving support from Jeff Yapalater who reached to his broader fishing community. Once I have their specific details, then we will trumpet their fantastic help. The path of ru23 is shown below. The point of the leak is clearly visible as the subsequent inertial motions. The large loop seen below is the path during the passage of Irene.

The currents of RU16 are strong, but despite the strong currents RU16 is making good progress heading back to shore. The current plans from EPA, NJ DEP and Rutgers calls for this glider to continue a series of cross shore surveys. The surveys will allow us to monitor the ongoing conditions offshore where the oxygen levels continue to remain low below the thermocline. The nearshore waters we have just entered shows the stratification has eroded. The nearshore waters are warm and fresher than the waters seen during the passage of Irene. The %oxygen saturation show higher values nearshore. It will be of great interest to monitor what is happening in the middle of the shelf especially as the summer phytoplankton remains present despite the large hurricane and the oxygen levels remain low in the mid-shelf bottom waters.

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Articles on August 2011 Phytoplankton bloom off of NJ

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RU16 samples through the hurricane

Irene has now made its way north of the Mid-Atlantic Bight leaving her mark inshore and along the coast.   RU16 fought the onshore currents associated with the northern edge of the storm until this morning when the currents switched as the eye passed overhead.  The last several surfacing show that the glider is now making much better progress offshore.   The glider is now offshore of the large phytoplankton bloom.  The map below shows the bloom location several days before the storm as the color background underneath RU16′s path.

Preliminary data from the glider shows that the impact of Irene was felt deep into the water column.   Before the storm, the ocean had a very warm surface layer above a very cold bottom layer.   The temperature gradient between the two is one of the largest in our global ocean.   You can see the pre-storm conditions in the plot below.  Look at the data collected between August 26 and August 28.

Irene’s influence is see near the left edge of the plot with a rapid cooling of the surface layer from 25 degrees C before the storm to 19 degrees C after the storm.  That is over 11 degrees F!  In addition the surface layer deepened significantly from 15 meters to almost 30 meters.  Irene has doubled the thickness of the mixed layer.

The mixing and deepening of the surface mixed layer is also seen in the dissolved oxygen data.   Relative to before the storm the mixed layer is now slightly lower dissolved oxygen concentrations in the near surface but has now delivered more oxygen rich water deep in the water column.   As with Ernesto 5 years ago, Irene did not mix away the strong stratification in the deeper waters of the mid-shelf.  RU16 will now turn back inshore to see how Irene’s influence was felt in the shallower waters coincident with the highest cell concentrations associated with the pre-storm bloom.

 

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Efforts by federal partners in response the bloom

Often our federal partners keep quiet about their efforts, but I would like to recognize some of the efforts they have been spearheading during the summer bloom.  Today I will concentrate on some of the efforts of our great partners NOAA fishery partners scientists who often quietly do great work without seeking any recognition of their efforts.

The Ecosystems Processes Division EPD at NOAAs North East Fisheries Science Center has been monitoring the status of the phytoplankton bloom and collaborating with other MARACOOS partners to assess the regional impacts of the bloom.  Two of EPDs field based research programs, ECOS and ECOMON, sample biological communities and features of the bottom and water column to gain a better understanding of the effects of ecosystem processes including phytoplankton blooms on fish and invertebrates.

Figure 1. ECOMON performs regional scale process based surveys in the region focused on water column characteristics and plankton

These programs have been designed to provide the best scientific information for the management of the ecosystem and its constituent fish and invertebrates.  These two programs are full partners in IOOS, sharing their data with the observatory and using remote sensing data in their operations in near and near real time.  The ecosystem monitoring program ECOMON performs broad scale synoptic surveys of the Mid Atlantic Bight and Gulf of Maine (http://nefsc.wordpress.com/category/ecosystem-monitoring-cruise/).   ECOMON, which grew out of MARMAP, has collected a time series of synoptic measurements of physics, phytoplankton, zooplankton and fish larvae since 1977.  Following the passage of hurricane Irene, ECOMON is scheduled to perform a survey that will include measurements of oxygen that is designed to assess the status of the regional ecosystem following the bloom and the hurricane Irene. Data from the ECOMON research ship will be passed in near real time to modelers working with MARACOOS.

The ecology of coastal ocean seascapes program, ECOS, performs finer scale adaptive surveys of ecosystem processes using advanced technology, smaller, faster, boats, and with survey designs informed by real and near real time data an models form ECOMON and MARACOOS.  Since 2004 ECOS performed holistic ecosystem surveys of the bottom and water column in the vicinity of two seascapes north and south of the mouth of the Hudson Raritan River estuary.

Figure 2. ECOS performed fine scale surveys of water column properties including oxygen and plankton during the summer bloom in the two seascapes outside the mouth of the Hudson Raritan River Estuary

The seascape south of sandy hook is located in a region that has experienced strong phytoplankton blooms and low dissolved oxygen in the past. On August 10, 11 & 16, 17 and during the bloom, ECOS performed surveys of the seascapes for water column characteristics including dissolved oxygen as well as plankton, and fish with fishery hydro-acoustics.

Figure 3. ECOS stations for plankton nets on August 17, 2011 during the bloom overlaid on MARACOOS the NYHOPS forecast model.

Figure 4. Vertical profile of water column properties taken at the Net station closest to the New Jersey shore in Figure 3.

The minimum dissolved oxygen measured during August 16 and 17 surveys seascapes was 4.2 mg/l and above critical levels.  We are still processes physical measurements, plankton and fisheries hydroacoustic data from those surveys.

Figure 5. Acoustic measurements of current (top) and backscatter from particles to fish (bottom) at the Net station closest to New Jersey shoreline in Figure 3.

ECOS also intends continue to coordinate adaptive monitoring activities with MARACOOS partners following the passage of Irene. These activities may include video monitoring of the bottom that can be compared with archived data to assess the impacts of the bloom (http://ecologyofcoastaloceanseascapes.blogspot.com/2010/08/methods-for-sampling-bottom-fish-and.html; http://ecologyofcoastaloceanseascapes.blogspot.com/2010/08/bottom-fish-invertebrate-communities-in.html).

Figure 6. Recent stations sampled in the region samples on NEFSC bottom trawl surveys that can be used to analyze the impacts of the bloom.


Figure 7. Images of the seafloor with seas scallops taken with HABCAM on the Scallop surveys of the mid Atlantic Bight.

In addition to the ECOS and ECOMON programs, the Northeast Fisheries Science Center completed its annual survey of scallops and other bottom dwelling animal throughout the MAB in late July.  NEFSC is also scheduled to begin its autumn bottom trawl survey of fish and invertebrates in late September. These two long term and broad scale surveys contain important historical information about abundance patterns of fish and shellfish populations that NOAA and other MARACOOS partners will use to assess the impacts of the bloom and other important ecosystem processes in the region. A partial list of ongoing NOAA NEFSC surveys of the coastal ocean can be found here

http://www.nefsc.noaa.gov/femad/ecosurvey/mainpage/why_nefsc_surveys.htm

So while we ride out the approach of Irene, I raise a toast to the hard working NOAA partners!  oscar

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The last chunk of data before the arrival of Irene

It is the calm before the storm, not that the calm actually exists.  Here is the update at the end of the day on the 26th.

Satellite imagery shows some contamination of clouds. But the plume continues to be advected eastward.  It appears that the plume is dissipating as it is being transported along Long Island.  Again the source of the high chlorophyll offshore is from the southern New Jersey coast.  The white represents some of the initial feeder bands of Irene arriving into the field of view.

The 25 hour CODAR and SST are shown below.  Strong upwelling of southern New Jersey and Delaware is feeding the Southern bloom.  The source warmer water of the south now has the primary circulation moving offshore along New Jersey, however there remains northward transport along the bottom third of the state.

The glider in the north waters of the Mid-Atlantic Bight (RU23), shows  enhanced surface turbidity associated with the high chlorophyll advecting eastward seen in the ocean color imagery.  The water shows high chlorophyll (fluorescence), particle load (optical backscatter) and interestingly high CDOM (determined with fluorescence).  The high CDOM is unique from the other waters that the glider encountered in the northern waters off New England.  The source of the enriched CDOM is likely from the summer bloom phytoplankton.  One hypothesis is that as the bloom begins to decline and the cells are are showing increased stress which has been associated with the increased rates of dissolved organic matter exudation.  The initial data figure shows the strong stratification, and as the storm arrives will be monitoring how much of the heat Irene takes from the surface ocean.  At the time of writing this blog, I received an unfortunate message, this glider is leaking.  The close proximity of Irene does not allow us to conduct a rescue, so we will have to hope it survives Irene while floating at the the surface.  This shall we say, is a major bummer……

To the south Ru16 continues offshore to deep water to survive Irene.  The temperature shows the strong stratification except in the regions of upwelling nearshore.  The surface waters remain supersaturated with the oxygen and the bottom waters continue to show low levels of oxygen saturation.  It will be very interesting to see the response of the oxygen to the passage of the hurricane.

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Hurricane Irene Update

National Hurricane Center has the eye passing over the bloom area on Sunday morning, so we’ll see winds from the east pick up on Saturday.

Heres the view from the afternoon MODIS imagery for an idea of scale.

Here is the current view of Irene and the MARACOOS CODAR network.  The MARACOOS HF Radar team has been hard at work preparing the network, and it is ready.  Most of our people are off the beach with only one more group to return from Cape Hatteras this morning.  The region is ready. We’ll have a final operations conference call before the storm at 9:30 am today.

Here is the wave forecast.  Peak waves are forecast to be over the bloom on Sunday morning.  These are very big waves.

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Evening update on August 25 2010

We have new imagery from the last few days and therefore we provide a satellite and glider update on the status MAB prior to the arrival Irene on the back end of Saturday. My opinion, is that Irene is serious please follow the directions of your local emergency responders.  Back to the evolving dynamics of the summer bloom,  we realized we needed a new satellite image footprint for the northern MAB which allows us to see the full swath along Long Island where the plume has been advecting the last week.  Thanks to RU satellite team.

What do the sea surface temperature satellite maps show? Below we provide three  sea surface temperature images from the August 23, 24, and 25.  To north on the 23rd-25th we show cold (purple) temperatures, these reflect a combination of northern cold water from the Labrador Current and Gulf of Maine combined with the contamination of cloud cover.  However the cold temperatures are likely dominated by the colder water to the north (based on scrolling back through the satellite records of the last few weeks (http://marine.rutgers.edu/cool/sat_data/?product=sst&region=northMAB&nothumbs=0)).  The cooler water is observed along Long Island (note the higher chlorophyll water offshore Long Island [see below] is associated with the warmer temperature water).  We definitely see impressive upwelling along the New Jersey coast line.  This in the humble opinion of this oceanographic salty dog, is that the sustained upwelling is fueling the usually large phytoplankton bloom in the summer.

What does the last three days of ocean color imagery show? Heavy cloud cover during the satellite overpass today did allow not to get a nice image, but below we show the chlorophyll dynamics over the 22nd, 23rd, and 24th.  The detached patch of high chlorophyll water that originated off New Jersey over a week ago continues to flow eastward along Long Island.  Over time the east ward flowing plume of chlorophyll does appear to be decreasing.  These decreases can reflect three processes that we are aware of, which are zooplankton grazing, particle flocculation, and/or physical dispersion.  We do not have the data (nor  any other coastal network on Earth!) to distinguish between the relative contributions of these processes. On southern New Jersey, the source of the high chlorophyll waters remains extremely productive. There are minor daily oscillations, but the sustained upwelling (SST images above)  supports the hypothesis that coastlal New Jersey is driving the high chlorophyll source waters fueling offshore blooms and not outflow from the Hudson river. Samples collected on Thursday suggest that the algae are mixed communities and are there are significant numbers of  nontoxic Gymnodium or Heterocapsa dinoflagellate species.  Given this the major concern is the status of the bottom water oxygen concentrations.

What do the gliders show? To the north we have RU23 which is now flying westward alongshore the northern shipping lines.  We were heading into the high chlorophyll plume, and today the optical light backscatter and chlorophyll fluorometers clearly showed when the glider crossed the high surface turbidity layer in the  waters in the upper 20 meters (see below).  The confirms very nicely the eastward flowing high chlorophyll waters seen in the satellite imagery above.

To the south we have the EPA sponsored glider mission continuing its surveys. This complements the REMUS surveys yesterday, see the post by Josh yesterday.  The glider today is being directed offshore to survive Irene.  The temperature profiles show the upwelling in the shallow waters as delineated by the lack of temperature stratification.  The oxygen saturation decreases reflects the shallow zones of upwelling, due to the decreased  variability in temperature with depth.  The main variability in the % oxygen shows the supersaturated values in the surface waters and low values at depth.  The million dollar question is how this dynamic will be altered over the next three days by the hurricane.  That is blog I hope to complete on Monday.  For those at sea off Mid-Atlantic this weekend, be safe.

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