Archive for the ‘Middle Atlantic Bight’ Category

late so a quick data update before a fishery glider discussion blog tomorrow

Thursday, March 4th, 2010

It has been a long, but great day with a big celebration of RU27 .  Two elementary schools, 4 deans, and 1 University President, ~40 undergrads, all wanting to geek for oceanography.  A good day, but we have glider flying tonight, so how does it fair?


The glider is heading cross shore and slightly south.  It is making good progress with storm driven southerly currents decreasing and the glider successfully adjusting to hit the prescribed way-point.


The decrease in nearshore currents was corrborated with the HF radar codar data.


The glider data does not show much structure in the vertical, except in the midshelf during the peak storm intensities. .  Except for low density water nearshore largely due to low salinity water, there is no structure in the optical or phytoplankton distributions.




MARCOOS 2010, Year of the Fish!

Wednesday, March 3rd, 2010

The first MarCOOS glider is deployed for the 2010 field season.  We have deployed ru22 and we will begin a month long journey heading down south to our most excellent partners.  We will add a second glider in the next few weeks to give us a northern view of the Mid-Atlantic shslide11elf.  Both efforts are timed to coincide with NMFS cruises to be conducted over the next month.  The glider deployment was accomplished just prior to the storm arriving on Tuesday night.  Since the storm arrival the surface currents have increased significantly in intensity as seen by the MARCOOS HF radar network.

Over the last 12 hours the currents in southern Mid-Atlantic bite have increased, and therefore it is not surprising that the glider progress has been limited, and the strong currents are carrying it to the south, slightly off it current waypoint offshore.  However given the strong currents the glider is making good progress. The glider shows some minor physical structure.  The major feature is a plume of low salinity water in nearshore waters.  Temperature shows very little variability and shows some minimal structure.



The glider temperatures agree with the available SST imagery.  Heavy cloud cover has limited our remote sensing this week.  But generally, what good images we did have, show cold temperatures on the shelf with the coldest waters found near-shore associated with the low salinity water.  The absolute temperatures measured by the satellites and the glider are in good agreement.


The low salinity water has enhanced colored dissolved organic matter, however there is no indication yet of much structure in the phytoplankton communities, therefore we are in  a good position to capture the spring bloom in the coming weeks depending on the seasonal warming trends.  Those warming trends,,, I am ready for!  Highest chlorophyll is  found at depth near-shore and optical backscatter (data not shown) shows no structure.  So while the storm was whipped up big currents it has not yet resuspended the sea floor.  Something to follow over the next day.


More tomorrow, lets see what the end of the storm brings us!

The weekend after…

Monday, November 16th, 2009

Well the Nor'Easter has passed.  Lots of storm erosion at the shore and the people are picking up the mess.  Meanwhile the gliders still fly.  We had many interesting conversations on Friday through the weekend.  On Friday, the RU and UDel gliders teams tried to figure out the best strategy to keep us from the beach given the worst case forecasts.  This discussion was had with the 2 gliders being smack dab in the middle of the shipping lane.  In an ideal world, we would have the 2 Southern gliders linger between the shipping lanes until pickup on either Tuesday or Wednesday.  The currents at the time made this look optimistic if not dream land.  But to our relief currents lessened and the gliders regained control and seem to be making a good go of moving where we want.  This bodes well for a Delaware Bay pick-up. The Northern gliders were directed to fly towards Tuckerton for a pick-up  One glider has already arrived and will linger.  The other glider which was advected well to the South is making good progress and should be there in a day or two.  One of the gliders will be cleaned and shipped to California for the US-Norwegian NORUS program next week.



While this was going the team was taking a deep breath with RU27 officially reaching European waters in Saturday.  Pick-up is scheduled for the first week of December.  Drake continues its path across the Atlantic, and the deep water Antarctic glider was launched last week and has surveyed the penguin feeding colony before heading out to sea to survey the shelf. It is never boring but always great to be at sea!




Nor’Easter! A big one!!!!!

Thursday, November 12th, 2009

As highlighted by David, the Mid-Atlantic got hammered today.  This was an epic event and caps off the 2 weeks of great efforts.  We had one week of calm conditions that allowed us to test several behaviors for the glider fleet, yesterday a very diverse group we coordinated a mission (based on community, not science), monday-tuesday model differences coordinated the fleet and tonight we face the strong fury of the nature awakened!  The general mission uploaded to the fleet today was to simple, try to hold position.  The currents have been building, and coastal innudation has been knocking out the CODAR sites, but as an ocean going person, all I can do is appreciate the awesome power of an angry sea and hope all people are safe.  The building CODAR currents are shown below, the sites being knocked out by the storm are denoted by the red dots in the last picture.





The weather and ocean models all showed the big storm. The weather model showed the big southwest winds.  Weather forecasts for tonight is starting to show the reversal of wind, and down south the eye is visible.


The ocean models all show the storm.  There are differences between the models but the strong southward flow is present in  all the models.  Yi and his group this week added an objectively weighted model ensemble.  The lowest two figures show the difference between the mean and objectively weighted ensemble model.  The mean ensemble definetely showed weaker southern flowing currents. There is alot interesting science to explore lining up the observations, weather model, and ocean forecasts.  The differences in  the picture to speak opportunity, and despite the variances, the fact I use observations, multiple models and see a "relatively" similar ocean is awesome.  What a great time to be an oceanographer and environmental scientist!



So these features are dramatic, let us check on our intrepid sea going gliders tonight.Not surprisingly, the gliders lose!  Most are being advected south, the northern glider is not impacted suggesting the southward wind driven currents is variable over the shelf.  Models support this. The depth variability in salinity  in the cross shelf have not changed dramatically.  What little temperature structure we saw in the water column has been erased.  This is coincident with a decline in chlorophyll.  Not surprisingly however, as the winds and waves pick, particle loads increase as seen in the optical backscatter.  The SEDIMENT & SAND returns for a late night Nor'Easter party.  As my Spanish colleagues often say "Force wind and honour all".







Storm warning!

Wednesday, November 11th, 2009

Storm David & all,

I was just informed of the impending weather for our gliders:

This is nearshore, it could be worse where some of the vehicles are:

Right now we are blowing 20-30 knots from the NE, smack into the gliders:

This is going to last into Sunday, its going to be very interesting.

I am not sure what the plans are for the gliders but each one is going to likely fall at least 20 miles to the SW.  Gliders can swim perpendicular to currents and get places but not into them.  I think that is what is happening for ru21.  The predominant current in that area is to the SSW:

I am sending these links because there is a Nor'easter coming and were not going to be able to go anywhere.  These are the links we usually use so that all can track.

No gliders are in danger.

ud_134 is going to be blown quite south.  This might seal the deal on a Delaware recovery I was throwing around.  We will see come Sunday and how we approach this storm and where we end up + remaining battery life.

ru05 will get blown too and hopefully have enough battery to make it back.  We will look at battery levels come end of the week to see if we need to turn off upcast sampling to buy us some time.

What we need to decide is what we want to do for the next 3 days or so for science. Were forcasted 30 knots through Friday.  Do we want to station keep (we will lose but will fall away the least amount) as best we can?  Waypoints to the NE at a decent distance will do this and leave current correction on.  If we want the gliders to get somewhere its going to take some fancy flying and should be discussed on case by case basis and no NE waypoint is likely going to be obtained.  We will start to see the blow soon, ru21 is seeing because of the direction it is heading.

I will continue to monitor the gliders and send out another email if need be.

Thanks for reading.
David Aragon

The Room Speaks and we have an OOI community decision

Wednesday, November 11th, 2009

Today at the community workshop at the end of lunch, we asked the room to decide on a group mission.  The room has spoken, and the answer is muddeled!!!!!  I gave the room around 100 people 2 choices.  The first choice was to fan out, the second choice was to come together.  In grand fashion it was a 50/50 split, so as a compromise we will bring two gliders together.  And we will fan two gliders out.  So here is the plan

Lets move RU21 and the Blue Hen to meet each other.  The rendevous site is 39 degrees and 26 minutes.

For the other gliders to split them out, RU05 and RU23 lets move them apart.  I don't have any strong opinions so leave that to the roup, I just want to avoid shipping lanes.

I am unlikely going to be able to make the phone call, can the group using the planning tools to drive home the potential to room tomorrow morning.  Make us look smart!!

The daily group image

Wednesday, November 11th, 2009

From Lisa to the group:

Attached are the most recent tracks,  11/11/09
Includes tomorrows EO-1 target.
Too cloudy to update SST.
FYI, target alert has been posted this AM for EO-1 tasking. (the red thumb tack)


OOI community workshop begins, I explore the ocean from the back of the room

Wednesday, November 11th, 2009

Quick update as I sit in the back of the room at the OOI community workshop.  We will be re-tasking the gliders based on input from the community here at the workshop.  So a quick check on the progress from last night.  The gliders have made good progress overnight and I believe we will be able to reach the way-points defined by the reachability envelop.  Of course there is variability in the envelops depending on the ocean forecast used and we should get valuable glider  information on which model envelop provided the best representation of the ocean experienced by the gliders.  Yesterday, the ensemble was spot on to the glider location.


Today I am going to be a biologist, once again showing my obsession with the Mid-Atlantic Bight winter bloom.  The bloom appears to be growing in intensity, and there appears to be increasing water column structure.  The phytoplankton appear to inceasingly found in the upper water column, earlier in the deployment the phytoplankton were distributed throughout the water column.  The intensity of the blooms appears to have increased as blooms have segregated int the surface waters.  One of the paradigms is that winter blooms are driven by light regulation.  Historical analysis suggests that the phytoplankton bloom in the winter when winds are low and the water column is somewhat stable allowing the cells to maintained in the upper water column where there is sufficient light to grow.  Looking at the temperature records from the gliders it appears that the water column shows some increased stability as indicated by the evolution of some moderate thermal structure.  The blooms appear to be associated with the changes thermal structure.  The salinity has not changed over the deployment period, with a nearshore slug of low salinity water.




Update on a cloudy Tuesday, but it is sunny in our heads….

Tuesday, November 10th, 2009

We had a great telecon yesterday.  I look forward to another great call today! The decision was to conduct two experiments.  The first experiment which was championed by Pierre was to send one glider North to survey the Hudson Canyon which shows some interesting features. Pierre's plan and reasoning was laid out in some figures which I have posted below.





The second experiment was assess how different models impact the glider path planner.  Using the JPL tools we checked with each glider the projected paths over the course of day.  The potential envelops of the glider being able to reach a specific location varied with model, not surprising as all the models show some differences.  This reflects differences in the models, the assimilation schemes, the assimilation data used, etc.  We for each glider chose a track where the "reachability" envelops between the different models showed the greatest differences.  For the three gliders, this lead us to send two gliders to the south and send the third north to complement the glider surveying the Hudson canyon.  we have another satellite pass on the 12th, so today's discussion will need include some of that location choices.  Unfortunately today is very cloudy,,,, it better clear out before the Hyperion system arrives.

JPL executive summary 11/10/2009

Tuesday, November 10th, 2009

Southerly winds are observed Tuesday with relatively weak amplitude (less than 10 knots). NAM forecast indicates a transition to the Northerly and Northeasterly winds in the next two days with increasing amplitude reaching 20 knots by Thursday. Excellent SST images are obtained on Sunday. No microwave data (TMI+AMSRE) were available Sunday, confirming the important role of the geostationary satellite data in the blending process. SST comparisons consistently suggest a band of warm model bias at the shelf break, probably due to the mislocation of the SST front simulated by these relatively coarse resolution (~4-km) models. The HF radar data on Sunday show a northward flow on the southern shelf, and an offshore flow north of the NY harbor. While the northward flow on the shelf is reproduced by most models, the four models show major differences in simulating the offshore flow on the northern shelf. We have added the UDel glider (ud134) to the glider data vs model comparison. It is interesting to note that the COAWST model has the near perfect agreement with glider temperature on the shelf, but the largest discrepancy in temperature off-shore (~3 deg) and in glider salinity on the shelf (~1 psu).