Archive for April, 2010

A Turn to the Northwest.

Wednesday, April 21st, 2010

Cook has crossed the center of the counterclockwise eddy located near 22 30 N, 61 W. Currents have switched and are flowing to the southwest, consistent with the flow in the satellite altimetry image. It is time to switch from a course to the Northeast to a course to the Northwest. The NW course will take us through the clockwise eddy centered near 24 15 N, 62 W. Distance to the new waypoint is just over 300 km. We are following Amelia & Kyle's green line north. We will continue testing and optimizing flight parameters along this green line until we hit 26.5 N. At 26.5 N, we turn east and start the transatlantic transect to the Canary Islands off Africa.

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Cook course set for the weekend

Friday, April 16th, 2010

Its a slower pace of life with the deep thermal glider. Last year Scarlet called every 8 hours, and since she was a surface glider, we were always responding to the combination of weather-forced and internal changes in the surface ocean. This deep glider slows the pace down even more than a surface glider. We are alternating between 7-8 hour single-yo (one downcast & one upcast) missions and 14-15 hour double-yo missions as Tod at Teledyne Webb continues his tuning of the flight characteristics. Once Tod has the flight parameters squared away, we'll spend some time on the sensor data. Once we settle in on a vertical speed profile, we want to compare a couple of CTD upcasts and downcasts on a double yo mission. All this can be accomplished while sitting off the CaRA testbed in Puerto Rico and St. Thomas, just like RU26. But RU26 is being recovered by our CaRA partners at the University of Puerto Rico Mayaguez. We want Cook in position on the western side of the 26.5 N transect at the beginning of summer. That means tuning as we go. Amelia & Kyle already started the path planning process, switching from last week's blue route to this week's green route based on the U. Colorado satellite Sea Surface Height (SSH) data seen below. John is setting up the NASA global Sea Surface Temperature (SST) maps, and the Navy HYCOM forecast model, for the google earth glider navigation interface. We'll soon post instructions on how you can download the google earth kmz files to follow along.

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Amelia & Kyle take the wheel

Wednesday, April 14th, 2010

A new glider, a new class, and two new pilots take the controls. Amelia & Kyle set their first waypoint this morning. Here is what we did.

First John shifted the Colorado altimetry window 2 degrees north. We typically capture an 8 degree of Latitude swath of altimetry data from the Colorado server. Because the Colorado surface current maps are generated on a different projection than google earth, a wider north-south band is more difficult to project onto the google earth globe. So we like to keep it narrow in this direction. East-west matters little - it can be almost any length in this direction.

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The most striking feature for us is the relatively continuous current that runs to the east along 26.5 N. I've highlighted the current it with a red line. The task for this semester's class is to get the glider Cook up to the 26.5 N latitude by the end of the spring semester. The summer class will pick up from there and hopefully fly us in close to the Canaries. Then the fall class takes over and flies us somewhere else.

The blue path north is the path we choose last week. The blue path was designed to fly the glider between the two counterclockwise eddies in located between 22N and 23 N. They are in yellow, so they are relative lows in sea surface height, just like low pressure storms in the atmosphere. Note how the circulation around the relative highs in red are clockwise, the opposite of the circulation around the lows. But this week it looks like these two counterclockwise, low sea surface height eddies have merged, and there is no current to ride north along the blue path. Then the blue path runs into a head-current about until it reaches the favorable currents at 25 N associated with one of the clockwise eddies. So Amelia and Kyle looked for an alternate route north. They filled in the green path. Its a slight shift to the west, taking us through the quieter parts of the yellow eddies, avoiding the head current between 23.5 N and 25 N, and getting us to the meandering current at about 25 N, 62.5 W. That will bring us up to 26.5 N.

A small adjustment

Saturday, April 10th, 2010

We have a slight increase in the currents to the southwest reported by Cook. Not enough to stop us, but why let it slow us down. We'll move the waypoint a bit to the east to try to avoid these small countercurrents. We are shooting for that strong current to the northeast in between the two eddies. We are trying to follow the blue line superimposed on the surface current field shown here.

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Implimentation Vertical transport

Wednesday, April 7th, 2010

Region: Off the coast of Africa we will monitor the upwelling with a series of gliders that will transect the upwelling region.

Spacial sample strategy: We will fly a small fleet of three gliders perpendicular to shore through a region of upwelling.

Time sample strategy: These gliders will fly every other month for three years.

Experimental strategy : The transect they follow will create a time series that will allow us to monitor the areas physical, chemical, and biological components. Each of the three gliders will have a different purpose. The first glider will have a CO2 sensor. This Sensor allows us to monitor the organic and inorganic carbon liberation in the upwelling areas off the coast of Africa. Once we get dependable data we will be able to get a good estimate on how much carbon is being liberated. The second glider will have an acoustic sensor and plankton sensor we will use for biology. In upwelling regions nutrients feed the biology therefore this will reflect nutrient levels in the water. The acoustic sounding instrument will focus on larger animals such as schools of fish feeding in the fertile area. The plankton sensor will be able to measure levels of biology in the water column and will also give us an idea of how much CO2 is being consumed by organisms. The third glider will have a CTD to monitor the physical and chemical components of the water.

Region: Off the coast of Antarctica

Spacial sample strategy: we plan to monitor upwelling with a series of three gliders that will focus on canyon regions that seem to funnel deep water to the surface along the coast.

Time sample strategy: three gliders will monitor the area during the spring and the summer.

Experimental strategy : One glider will have a CO2 sensor which will allow us to see how mucghCO2 is being liberated in the arctic region. Another glider will have a CTD for the physicical and chemical components and the third glider will have an acoustic sensor for monitoring biology. The biology we will be studying in Antarctica Consists of plankton and small baitfish. With this information we will be able to track bait fish movement and a close component which is penguin migration.

Path Planning Begins for the Thermal Glider – Cook

Wednesday, April 7th, 2010

My last blog entry was Dec 4, 2009. A long story on the recovery of RU27 off the coast of Spain after it spent 221 days at sea - the first underwater glider to cross the vast Atlantic. Soon we start another journey across. This time with a thermal glider built by Teledyne Webb Research named Cook. Scientists from Teledyne Webb (Tod) and Rutgers (Chip & Tina) launched Cook in the Virgin Islands back on March 21, along with RU26. Both are undergoing their first sea trials. RU26 is heading west to Puerto Rico for pick up by our U.S. IOOS partners in the Caribbean Regional Association (http://cara.uprm.edu/). Josh is preparing RU26, a deep electric glider, for his trip to Antarctica where they plan to deploy RU26 with a helicopter from the ice edge in the Ross Sea. Cook is heading northeast into the open sea. Once Cook is done with its sea trials, Teledyne Webb Research is going to hand the keys over to the Rutgers students that flew RU27 across the Atlantic last year. Rumor is Cook is a fast glider.

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The plan this summer is for the Rutgers students to fly north from the Virgin Islands to a latitude of 26.5 N. There they will turn Cook to the east and sample along this line of latitude to help determine how glider data can contribute to the Rapid Climate Change program. http://www.noc.soton.ac.uk/rapidmoc/ The plan is to continue all the way across to the Canary Islands off the coast of Africa.

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The path planning right now is finding the best route north to 26.5 N. For that we return to the University of Colorado's geostrophic surface current data derived from the satellite altimeters. Even though the altimeters are just giving us the surface currents and the thermal gliders are diving to 1200 m, the mesoscale eddy field we will be navigating extends deep into the water column. If we head straight north, we hit a counter current that pushes us south. If we follow Drakes path from last year to the northeast, the unlabeled yellow line on the map, we again hit counter currents. So the initial plan is to follow the wavy blue line, first to the Northeast, then turn north. This will keep us flying with the currents or in weak currents, avoiding the countercurrents when we can.

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If all goes well, we should be visiting our friend Antonio in the Canaries in the fall.