The final NAB08 cruise on the R/V Bjarni Saemundsson departed Reykjavik the morning of 25 June with Mary Jane Perry as Chief Scientist and Keith Van Thiel as the glider ‘guy’, Kristinn Gundmundsson for primary productivity measurements, Katja Fennel (now a sea-going modeler) and Lindsay Dinsmore for water sampling. Very unlike the deployment cruise in early April, this trip sailed on relatively smooth seas.

We spent the first day in the operating area searching acoustically for Seaglider 142, who had operated flawlessly for over 2.5 months, but suddenly went silent the day before we left Reykjavik. No luck. On 27 June we did our standard calibration procedure with a simultaneous CTD profile and glider dive, with Amanda Gray piloting Seaglider 141 from Seattle; four hours later, we successfully picked up the Seaglider with adept help from the crew. This procedure was repeated on 28 June for Seaglider 140.

Before returning to Reykjavik on 1 July when we officially declare this highly successful field program over, we will spend a day doing more CTD profiles and water sampling, then head slightly south and east to deploy two ARGO floats for Herve Claustre and Antoine of Villefranche-sur-Mer.

Thanks to all who have followed our field program. Please stay tuned for updates on our results.

Over two months into the experiment, and three gliders continue operating out of the initial 6 platforms. The Bjarni Saemundsson rescued one float and one glider. The remaining gliders will continue executing a fixed repeat pattern through June.

So far, the project has captured the growth and saturation of the North Atlantic Bloom south of Iceland using a combination of autonomous floats and gliders and research vessels. A remarkable degree of spatial structure has been revealed apparently due to modulation of the bloom intensity by ocean eddies. Despite the strong structure on the 1-20 km scale, there is a clear seasonal pattern revealed by averaging over all of the platforms. The progression of the bloom has been marked by changes in the dominant phytoplankton type and clear evidence of the export of carbon through sinking from both traditional and optical methods.

After 50 days operating, the second float and one glider have malfunctioned, leaving three operating gliders. The Knorr finished a successful cruise this week and discharged the science crew in Iceland.

A rescue cruise on the Bjarni Saemundsson is being organized for the errant platforms. For approximately the next month, we will operate the gliders alone in a coordinated pattern. They will be recovered in July on a final Saemundsson cruise.

So far, the project has captured the growth and saturation of the North Atlantic Bloom south of Iceland using a combination of autonomous floats and gliders and research vessels. A remarkable degree of spatial structure has been revealed apparently due to modulation of the bloom intensity by ocean eddies. Despite the strong structure on the 1-20 km scale, there is a clear seasonal pattern revealed by averaging over all of the platforms. The progression of the bloom has been marked by changes in the dominant phytoplankton type and clear evidence of export of carbon through sinking.

As of May 17, 2008 the North Atlantic Bloom experiment is fully operational and gathering fascinating data.

Two floats, 4 gliders and the R.V. Knorr are operating together to map the three-dimensional structures of ocean physics, biology and chemistry. More detailed measurements are being made from the Knorr.

Such glory is fleeting. As of May 18, there is only one float operating, but this should be sufficient to continue.

The data indicates that the bloom is close to a maximum. Overall, the levels of chlorophyll, backscattering, attenuation, and oxygen have remained relatively steady for the last week, but with significant variations in space. Much of this variation appears to be associated with an anticyclonic eddy. We have done a good job of mapping the structure of the eddy and the associated modulation of the bloom. This should be a particularly interesting aspect of the data to analyze.

There are some indications from the plankton data taken on the ship that the bloom is starting to fade: diatoms are sinking to depth and the species composition is starting to change. The Knorr may catch the beginning of the end of the bloom before heading back to Iceland in a few days.

Not much new to report. The Knorr folks must be very busy, but I have few details. The ship completed a large survey a few days ago and is now doing important things.

Floats and gliders continue to operate well. The glider pilots continue to increase in skill and the gliders are now operating consistently close enough to the floats that we can begin to map the variability.

The float is getting closer to Iceland. This was not anticipated in drift climatologies. At worst, we may drift into Denmark Strait, which is not so bad.

At the present time, one float is tracking the mixing layer and the bloom that is occurring within it. Four gliders and the Knorr are surveying around it. The Knorr is beginning more detailed studies of biology and chemistry of the bloom.

Continuing gale-force winds have kept the mixed layer at 50-100m depth. The strong bloom signatures, i.e. high oxygen, chlorophyll and scattering, have been distributed to this depth, and surprising, rather deeper for some of them especially dissolved oxygen, which is now at or near saturation (by our sensors) throughout the upper 200m, a big change from the pre-bloom levels which were as low as 94% saturation. The upper ocean continues to bloom, despite the vigorous mixing, with our measured chlorophyll ranging from 1-2 ug/L and dissolved oxygen reaching 103% of saturation.

Our vehicles continue to operate well, despite some glitches. The errant float was recovered and we are diagnosing its problems. Given the problems in predicting the floats' tracks, the combination of 4 gliders surveying around one float may be what is necessary to get sufficient spatial information around the float for later analysis of the space-time patchiness of the bloom.

The weather is expected to moderate for a while this coming weak, perhaps leading to a more intense surface bloom.

We are pleased and a bit surprised that three weeks since vehicle deployment the experiment is operational and the ocean is blooming. One float is profiling to 200m on a daily basis and four gliders are surveying around it. The Knorr scientists are gathering in Reykjavík and will begin their cruise next week.

We are slowly bringing the float and glider sensors into calibration based on the early April data. This will continue with the Knorr cruise. We should have some maps comparing the satellite images with in situ data soon.

One of the focuses of this experiment is the biophysical interactions resulting in biogeochemical patchiness. The new "featured data image" shows the amazing amount of variability as the bloom develops. We are looking forward to understanding this.

The spring bloom appears to have begun. Despite the significant variabilility in pre-bloom conditions, all 4 gliders and the working float show higher chlorophyll, oxygen, scattering and attenuation in the upper ocean. More details are posted on the web site.

Eighteen days after vehicle deployment, one float has died, but will probably be rescued and revived in a few weeks on the Knorr. The other float is fine. Four seagliders are working well, but are having trouble staying close to the floats due to strong and variable currents.

The web site is rolled out today. Welcome to new visitors.

Scientists will begin mobilizing for the Knorr cruise later this week in Reykjavík.

Two weeks after the vehicle deployment, one float has died, but will probably be rescued and revived in a few weeks on the Knorr. The other float is fine. Four seagliders are working well, but are having trouble staying close to the floats due to strong and variable currents.

Both the in-situ and satellite data show a high degree of variability in space and a time. Chlorophyll fluorescence varies by a factor of two on 10km scale, reflecting a strong eddy field on this scale. The weather alternates between strong storms, mixing the ocean to 150-200m, and calm periods during which restratification occurs.

Overall, the ocean has significantly stratified, but there is no clear evidence yet of a bloom that rises above the background variability. We expect one soon.

We will do a full roll-out of the web site next week along with a longer report on our status.

The Knorr sails in early May for the intensive period of the experiment.