Western Channel Observatory Blog

Some pictures of our routine maintenance trip to the L4 buoy on Monday 12th July. We found large amounts of bio-fouling on the instrument cage. After a clean and a quick check of the functionality of all the sensors the cage was returned to the moon pool in the buoy and only missed one data acquisition.
Also we re-fitted the AIS system on the L4 buoy after urgent updates had been installed. Both buoys are now reporting full AIS information as well as all scientific parameters.

Bio-fouling of buoy instrumentation

Anti-fouling paint on the sensors (black) is working well

Heavily fouled

Performing some system checks on the instrumentation

Andrew installing the new GPS for the AIS system

As mentioned at the “Last Season at the Observatory” meeting in June it is a good idea for those of us who are data collectors to submit data to Pangaea.  This is so we have a tangible output for our efforts in the form of a publication.  Below are some more details, together with an example, of how to do this.

Pangaea data submission for CSV files
=====================================
1) Get data into format for submission (suggest CSV or other delimited)
2) Make sure the data is adquately quality controlled – as if you were
submitting to a journal or BODC
3) Write a short paragraph describing the data, how and where it was collected
4) Visit the web site:
http://www.pangaea.de/about/
5) Email the data and the description to info(at)pangaea.de

Example data description
========================
Recommended citation for Pangaea
——————————–
Smyth, T.J. and Fishwick, J.R. Temperature and salinity profiles at 10 m depth
resolution from station E1 in the western English Channel.

Data description
—————-
The data files:

western_channel_observatory_e1_ctd_temperature.csv
western_channel_observatory_e1_ctd_salinity.csv

contain depth profile temperature and salinity data extractions at 10 m depth
intervals for the Western Channel Observatory long-term hydrographic series at
station E1 (50 02′N; 4 22′W) in the western English Channel.  The 10 m
extractions have been determined from the closest depth bin measurement.  They
do not represent the average over a 10 m slab of the water column, but rather a
slab around 0.25 m thick for the electronic measurements.

Early in the time-series (1903 – 1985), temperature and salinity depth profiles
were determined using reversing mercury thermometers and salinity bottles.
Since 2002 the data have been acquired electronically using a SeaBird SBE19+
CTD.

A summary of these data are published in the annual ICES Report on Ocean
Climate.  An analyses of these data has also been published in Smyth et al.,
(2010).

References
———-
Holliday, N.P., Hughes, S.L., and Beszczunska-Moller, A., (Eds). 2009. ICES
Report on Ocean Climate 2008. ICES Cooperative Research Report No. 298. 66 pp.

Smyth, T.J., Fishwick, J.R., Al-Moosawi, L., Cummings, D.G., Harris, C.,
Kitidis, V., Rees, A., Martinez-Vicente, V. and Woodward, E.M.S. (2010) A broad
spatio-temporal view of the Western English Channel observatory. J. Plank. Res.,
32, 577-737

Whilst on a visit to the L4 buoy a few of us were fortunate enough to witness two large Basking Sharks swimming very close to the vessel.

Following up Tim’s post on the bloom at E1, here’s a classic Aqua-MODIS chlorophyll scene showing the wider picture.

Chlorophyll map from 17 June 2010

This shows a clear distinction between L4 – in a low chl-a nutrient depleted area, and E1 – at the edge of a Channel bloom. Also note the higher chl-a concentrations within a few kilometres of much of the SW coastline.

7-day thermal front map up to 07 June 2010

The abundant plankton (and strong oceanic thermal fronts) has attracted basking sharks to the coast of Cornwall. WCO imagery were featured in an article in the Cornish press today. As the journalist got confused between thermal fronts and ocean colour, shown above is the front map I provided.

The E1 buoy is now sending data back loud and clear following some investigations into the aerial configuration.  There are still some issues regarding the camera (requires a new card) and the voltage reporting (new drivers) – but we are getting there slowly.  The really great thing was that the AIS is working well from E1 and we know 24/7 the position of the buoy (just in case things go wrong)

From the buoy and the satellite data it appears that there is a bloom at E1 (in fact – classically, as described in various Pingree papers and Smyth et al. 2010 the bloom is more mid-channel with E1 clipping the edge of it).  Interestingly, when you look at the CTD data from E1 this week – you can see that the surface values are only giving us a small part of the picture.  Most of the bloom (in terms of chlorophyll concentration) is around the 20 m mark, at or around the thermocline.  It would be interesting to know which species is dominating out there.  My money would be on something like Karenia.

For links to the various data sources see:

buoy data: http://www.westernchannelobservatory.org.uk/buoys_E1.php

CTD data: http://www.westernchannelobservatory.org.uk/e1_ctdf/index.php?request=100617

satellite data: click on links on the website for the EO data (URLs too long for this blog …)

Despite some swell the E1 buoy has now been successfully redeployed.  The AIS is showing the buoy to be in the correct position – this is a first for us as we have not been able to receive the AIS signal from Rame Head before due to a poor aerial (throughout 2009).  Thanks to the crews of Quest and Sepia who made this possible.

Tim

Despite valiant efforts yesterday (27/5) the E1 buoy didn’t make it to full deployment.  The tides were too strong for putting the buoy securely on the moorings and a decision was made to abort and wait for the good-weather, neap-tide combination.  One good thing came out of the tow all the way out to E1 – the AIS has been checked and we now have reception all of the way out to the position of E1 – giving us security in knowing the buoy is in the correct position.  This is something we have not been certain of before.

L4 data is now being received from the roof of PML – and we are hoping to do the same for E1.  This will mean a trip up to the roof to check on things rather than wrestling with summer traffic across the Torpoint ferry.

Tim

This week has seen major changes in phytoplankton smaller than 10 µm compared to the 4th May (see blog for 5th May). The Multisizer figure shows that phytoplankton size distribution is the same from the surface down to 25 m and that the Phaeocystis sized cells (5.5 µm last week) are absent. It is only at 50 m (black line), near the seabed that cells of 6.2 and 7.2 µm appear. Otherwise, the phytoplankton are numerically dominated by cells just over 3 µm throughout the water column with abundance in the region of 50,000 per mL at 50 m. Lines on plot: red = surface, green = 10m, blue = 25m, black = 50m

Here are a couple of images I prepared to show the developing spring bloom around UK waters. It all happened quite suddenly with the recent spell of warm and sunny weather. Sorry these are a few weeks old now, I’ve been away from the lab too often…

These are both 3-day composites for 11-13 April 2010: upper image: chlorophyll concentration false-coloured blue to red, using turbid water algorithm (with scalebar). The bloom is shown as everything orange-red on the chl-a map. The majority of the UK and Irish coast is affected, particularly Liverpool bay, E England, E Scotland, N Devon and Cornwall.

Lower image: true(ish) colour composite using red, green, blue channels to show the bloom as varying shades of greener water. Dark blue is clear water, and the greener the water, the higher concentration of plankton. The bright areas around the Irish Sea and English Channel show where there is also sediment in the water, e.g. from estuaries.

There is usually a spring bloom of plankton like this around this time, though I believe this year may have been a little more sudden and intense than average, perhaps because March was cooler and cloudier than normal. So there was less plankton growth earlier, and plenty of nutrients waiting for when it did suddenly become sunny and calm.

Aqua-MODIS chl-a composite 11-13 Apr. 2010

Aqua-MODIS 'true' colour composite 11-13 Apr. 2010