I was checking out the latest plots from SG130 yesterday, and I noticed a very interesting feature. The glider is a ways south of Newport, over 100 km offshore, heading northbound. In the last several profiles, in addition to a surface chlorophyll peak (~50 m), there appears a second chlorophyll maximum around 200 meters. Check it out:
The feature shows up in the backscattering data, too, and is not associated with any change in water mass characteristics (temperature or salinity). Is the deep chlorophyll max (DCM) an older surface bloom that has been advected offshore and is now sinking out? It would be neat to look at the glider and satellite data going back in time to see if I could track the origin of this DCM. Time to hit the literature and refresh my memory on the coastal dynamics of summer phytoplankton blooms off of Oregon. Any thoughts from our readers on origins of this feature, and whether or not it is an annual occurrence? I’ve got SG130 data from last summer, too…
Last Monday (7/13/09) we deployed SG130 around NH15 (Newport Hydrographic Line). Conditions were great – almost no wind and very small swells. Captain Mike took us out on the R/V Elakha, OSU’s trusty day-trip vessel. Here you see Justin and I easing the glider off of the fantail, with Mike’s help.
If you want to follow SG130 during it’s mission, follow this link to the Glider Research Group web page. It will be traveling on a path that looks like a capital “E”, where the top of the “E” is the NH line, the middle line is a visit to Heceta Bank, and the bottom is an east-west line near the mouth of the Umpqua River. The last time that SG130 was deployed, we saw some very interesting patterns of sediment resuspension – I am hoping that we see the same patterns again.
I’ve been tinkering around with Seaglider data that was collected off of the Oregon coast from September – November 2008. SG130 is equipped with a WET Labs ECO-Puck, which provides us with estimates of Chlorophyll-a concentration (biomass proxy), colored dissolved organic matter (CDOM) fluorescence, and the particulate backscattering coefficient at 660 nm (proxy for particle load, particulate carbon, etc.). The Seaglider also has an oxygen sensor, which will be of great value when seasonal coastal hypoxia sets in again.
At any rate, here is a preliminary plot of data collected along an east/west transect, at apprximately 43.7 N. A large plume of particles being advected off of the shelf is evident in the backscattering data (middle plot on right – ignore the bathymetry for now). More plots to come in the near future!