Archive for November 3rd, 2009

Evening OSSE update 11/3/2009

Tuesday, November 3rd, 2009

Evening sets on the second day of the OOI CI  OSSE. There was a productive 2PM call, and we are filling the write board in the cool room with suggestions provided by the IOOS and OOI CI team.

For the ocean conditions:
The  changes in the Mid-Atlantic Shelf tonight are a big current reversal in 24 hours.  Last night I was bloggin' about the northward flowing current, and tonight I lament the south flowing surface currents.  These strengthening southern flowing current has been building over the day according to the CODAR data.  You would think the shelf could make up its mind by now.  The forecasts are provided in the earlier JPL summary blog.

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So do is the reversal supported by model outputs?  Sure enought the ocean models show the south flowing currents nicely.  We show below the output from the JPL models.  Clearly in the CODAR and models the Mid-Atlantic Bight the currents are flowing to the south.  Given this how are the gliders doing?

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The reversals, in 6 depth averaged currents show a muddled and nasty looking glider fleet.  In general the gliders showed southward flowing currents in agreement with the CODAR and numerical models.  A few random vectors showed northward flowing currents, and we will need to dig through the data to see if it is local variability ?  So given that we are testing the CI planning and prosecution software, how is the ASPER/CASPEN software faring tonight?  The gliders over the last data transfer show progress to the north.  For the experienced glider watchers, watch the next update to see how we feel the southern flowing current.  Will we keep the the steady nothern progress? The way points for the gliders for two southern gliders are two the south, which is surprising given the southern current.  This to me looks like it shows the earlier influence of the prior period of northern flowing current.  We will see, next call in tonight should be interesting. At the 2PM call we decided as a group to keep the glider on the path planning waypoints from yesterday (blue line in the 2nd figure below).  Lets see how we progress.

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What are the gliders seeing?  A quick recap of the vertical structure seen by the gliders. Salinity shows the same cross-shore variability with near-shore waters showing slightly lower saline waters.  Temperature shows an interesting slug of warm water in the mid shelf, looks like two water masses based on the salinity structure, as there is vertical structure in the salinity and the temperature profiles are near isothermal. The outer half warmer waters and cooler waters in the mid-shelf show enhanced chlorophyll.  Values are close to ~3 micro-g/L, close to the mean winter bloom values.  I have a graduate student who has been analyzing a decade of satellite data, her analysis suggests the winter bloom is found from around water depths of ~20m - 60m. We seen this enahnced slug of plant material growing at depths 25-40 meters.  As a betting by next week, my bet is the blooms extends to around 55m. Is this the start to the winter bloom?  Man if it is, as a geek scientist, I am stoked! Interestingly,the nearshore shows higher backscatter.  This is not true offshore in my hopeful winter bloom.  This would be consistent with low phytoplankton waters but the shallow water depths where significant waves lead to sediment resuspension.  The resuspended sediment often shows enhanced optical backscatter values, and these waters showed low chlorophyll fluorescence indicating low phytoplankton biomass.  Colored Dissolved organic matter showed slight variability cross-shelf, but nothing dramatic with slightly higher values nearshore.  these enhanced values correlate with the low salinity water which is consistent with freshwater inputs. For the ocean geeks, we have several different water masses indicated by the salinity, temperature, particle, chlorophyll glider data.  We have a valuable data set to study the transition period in the Mid-Atlantic from stratified to well mixed conditions!

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The JPL daily update

Tuesday, November 3rd, 2009

JPL Executive Summary of 11/03/2009

NAM forecasts indicate winds in the range of 15~20 knots for the next two days. Northeasterly winds Monday and Tuesday will switch to Easterly by Wednesday and Northeasterly again by Thursday but with much weaker amplitude (less than 10 knots). Even though with more clouds on Sunday, there is still reasonable satellite coverage for SST. We receive three ocean model forecasts Monday. Models still show warmer SST on the shelf break. The variance of the ensemble forecast shows major differences in salinity at the fresh-water input locations. On Monday, ensemble predictions were used by mission planning software to compute optimal current-sensitive submersible paths and retask three Rutgers gliders: ru05, ru21, and ru23. The planned paths from each of the three available models showed good agreement over the area of interest. However, all three gliders didn’t go very far during the last 24 hours, in contrast to the eastward direction as predicted by the ensemble model forecast. Examination of the ensemble forecast variance indicates major differences in subsurface current among the three model forecasts around the current glider locations.

“Next time your found, with your chin on the ground”

Tuesday, November 3rd, 2009

"Theres a lot to be learned, so look around"

Hello all,

Just when we thought that things were starting to become easy, a dramatic turnaround happened. The CODAR data that has been streaming in from Spain has stopped coming in. The last available dataset is from October 21, 2009 at 10 pm EST.

Fortunately, we have been busy working on other projects while they fix the CODAR sites over in Spain. Al has gotten us the information that we need (from Antonio) to convert the PLOCAN wind data to a coordinate scale. This will help us plot the direction and magnitude of the data correctly in MATLAB and then import it into Google Earth.marcoos

We have also worked on importing the MARCOOS data into Google Earth. This will help our engineers and pilots in our glider launches in the Mid-Atlantic Bight. This kmz along with the Spain kmz, PLOCAN kmz, and CODAR status kmz will be available on the web shortly.

Mike and Lisa

November 3, Morning Update

Tuesday, November 3rd, 2009

The gliders have been dancing a nice tango last night.  Evening and morning conversations with Chip & Dave, has us thinking this largely reflects the strong conditions on the shelf.

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The currents measured by the CODAR support this interpretation.  Below are the currents from last night and remember the nominal speed of a glider is 20-30 cm/s.  Hopefully currents will lay down and we can start making headway.

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What do the forecasts show for currents? Two forecasts for 11/4 are shown below, and they  suggest currents will begin to lay down.  That would be most excellent.

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How well are the current forecasts doing?  To look at this we compared model outputs against measured Codar currents.  While there are small differences, on the whole the models appear to be doing very well.  This gives me faith that we will start to make progress today.  We shall see.

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Drake’s first challenge along the MOC line

Tuesday, November 3rd, 2009

Drake encounters his first challenge along the 26.5 N line. He is about to cross the southern edge of a clockwise rotating eddy. The surface currents will be against him.  But Drake is a deep glider, diving to 1200 m.  We'll see how we do over the next few days.

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Scarlet continues to keep her nose pointed east as we move south with the currents.  The combination is a southeast track.  The objective is to use all of Scarlet's speed to fly perpendicular to all the current arrows, trying to move along the thin white line that takes it through currents to the east and then currents to the northeast.  The distance along the wavey white pathline to the Spainish EEZ (thin yellow arc) is 250 km.  The white line is extended into Spanish waters another 200 km, so that its total length is 450 km.  If we did 15 km/day, thats 30 days.  We likely will not keep this speed for the full 30 days.  The think yellow stright line marks 12 W.  This is the western boundary of the strong alongshore current that runs south, and the outer boundary of the vessel traffic we see in the AIS.  Crossing that boundary will like put is in a current that is faster than the glider, and we would be advected south along the coast towards Lisbon as we waited for pick up.

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weather group update for week of 11/3

Tuesday, November 3rd, 2009

good evening everyone

this week justin and i checked out current patterns of the jet stream and off the coast of Spain/Portugal  its looking like speeds up there are somewhere around 50 mph. Here is the current pattern it is following. 2xeu_jtthis map correlates nicely with what the waves are currently doing shown in this map where there is a system of elevated wave heights with a slight lag from where the faster wind speeds are shown abovewave000seeing the patterns here it looks important to keep updated on how the gulf stream is doing to try and see how the waves will be come time for pick up.

We also checked out the weather conditions for the first week in December or both Vigo and Lisbon for the past couple years.

Vigo 2008-

average temperature is about 8-9 deg C and there is thick cloud cover along with fog every day.  there is also i bit of rain

Vigo 2007-

average temperature is about 10 deg C and again there is a lot of fog and cloud cover.  this time there was no rain

Lisbon 2008

There is a significant amount of precipitation as there is rainfall just about every day with a little bit of fog as well.  Average temperature is about 13 deg C

Lisbon 2007

For the beginning of the week there is a little bit of drizzle here and there but overall the skys are clear until later in the week when the temperature drops a bit and there was heavy fog observed.  Average temperature was about 12 deg C.

Looking at the previous years, there seems to be a correlation between amounts of fog and temperature being that if the temp is below about 11 deg C there is more fog observed

That is all for now

justin and nilsen