Cruise Day 25
Speed 0 knots (kts)
Course N/A
Location Makarov Basin, approx. 139nm S. of the North Pole
Depth 3949 m
GO DEEPER DISCUSSION: (see previous journal for the questions.)
We had a warm front bring the moist air and snow in yesterday morning. Warm fronts aren’t always warm, but the air they deliver is warmer than the air being replaced. Today we are back to much colder conditions, but the Sun is out. Clear, high pressure systems like the one affecting today’s weather are typically colder, as cold air is more dense (thus helping to contribute to the high pressure.) Additionally, clear skies let more infrared radiation from the Earth escape to space, a cooling effect. Clouds absorb most infrared radiation leaving the Earth’s surface and re-radiate some of it back down, providing an insulating effect and keeping temperature from dropping as low as it would without cloud cover.
TODAY’S JOURNAL:
We’re on the final sampling operation of the super station we’ve occupied for the last couple of days, about to head north one more time in our final approach of the North Pole. We’ve drifted several miles north and east with the ice pack, taking us back into the Western Hemisphere. The Sun is brilliant, doing a slow lap around the ship low on the horizon today. At times, a fogbow has developed on the horizon opposite the sun. I was up until 4am last night helping with the GEOTRACES deep cast, and getting ready today for a talk I’ll give for interested members of the crew and science team on bird migration, so today’s journal will be a little short.
The re-appearance of the sun also delivered a nice fogbow today over the pack ice.
Yesterday I discussed how Team Aerosol is capturing atmospheric particles as a part of the larger GEOTRACES picture. I mentioned how particles can fall directly into the ocean, or be delivered by precipitation to the Earth’s surface. Rain droplets and ice crystals in clouds usually precipitate out onto microscopic particles called condensation nuclei, and so can be a source of particles for the oceans as precipitation falls. Since it was snowing pretty hard yesterday morning, there was a good opportunity to sample the precipitation for later analysis of trace metals they may be carrying. Chris Marsay (Post-doctoral Research Associate at Skidaway Institute of Oceanography in Savannah, Georgia) and Ana Auguilar-Islas (Assistant Professor, School of Fisheries & Ocean Sciences, University of Alaska Fairbanks) climbed up to the flying bridge in the snowstorm to deploy a pair of specially-designed snow collectors. They look kind of like 2-liter pop bottles with the bottoms cut off. These bottles are pointed into the wind with their lids left off, which lets air blow through while settling out the snow inside the bottle. After the snow stopped, Chris & I went back up to collect the bottles. Chris put the lids on and secured them in a clean bag. Then he brought them to his lab space in the bubble (see Building the Bubble journal, July 25) to thaw the snow and collect the resulting water.
Chris Marsay and Ana Aguilar-Islas deploying snow sampler on the flying bridge of USCGC Healy.
Back in the bubble, Chris Marsay places the snow samples under his heap-filtered clean air hood to thaw prior to collecting the melted water.
The collected water is stabilized using acid, which prevents metals from precipitating out of solution while it is in storage. It also dissolves metals carried by particles in the snowflakes without dissolving the particles themselves. Once at home, the Inductive Coupled Plasma Mass Spectrometer I described yesterday is used to profile which isotopes are present in the melted snow.
GO DEEPER!
Why do you need the Sun at your back to see a fogbow or a rainbow?
Aloft Con web cam updated every hour
Healy Track
That's all for now. Best- Bill