Evening OSSE update 11/3/2009

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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