Thursday, July 7, 2011

Making the Plan

--Scott Miller (SUNY Albany)

The science team meets nightly in the Knorr Theatre to discuss the current status of the measurement systems and to shape the sampling strategy for the upcoming days.  Since a main goal has been to find a high-DMS phytoplankton bloom (see Tom’s earlier post), the ship track is a topic of nightly discussion.   
The remote sensing images (e.g, chlorophyll – see Fabricio’s post) are displayed on the bigscreen TV, and we spend a fair bit of time trying to understand what’s in the images (besides clouds), and to project where we can find high DMS and high dpCO2 (see Matt’s post).  The recent image shows our ship track (Figure 1, thick black line), with 24-hour periods on stations marked with an “S”.  As Tom will detail in a later post, we eventually found a high-DMS bloom at station S4.  Great news!  

Figure 1. Chlorophyll-a
So, you might think that after searching for 10 days and finding the bloom we would remain in it to sample for an extended period.  But… we also need to consider the weather.  We are trying to collect data over a broad range of conditions (i.e., wind speeds) to better understand factors controlling gas exchange.  Figure 2 shows results from our 2007 cruises.  You can see that most all of our data is for wind speeds below 10 m/s (or about 20 knots).  During this cruise we would like to extend this to higher wind speeds where whitecaps are thought to be important (see Brett’s post).   

Figure 2. Knorr 2007 results.
The weather forecast for the next 4 days at station S4 predicts very low wind speed (below 15 knots) – not interesting for our measurements.  Alternatively, the forecast for our next station (S5, 50N, 048W) is more “interesting”, with a low-pressure system moving in and the potential for gale force winds.   So, we are now in transit with an estimated arrival time at S5 of Saturday morning.  The low pressure system is projected to pass over that location on Sunday and Monday.  Stay tuned…