KenMankoff

Sextants

Yesterday we did a transect along the face of the glacier. Every 15 minutes we fired an XBT down to measure temperature, pinged the bottom of the ice shelf with our multibeam bathymetric mapper, used the radar to get the distance from the ice shelf, and used a sextant (old school!) to measure the angle the ice shelf fills in our field of view. With a bit of geometry we now have a rough estimate of the height and draft of the ice shelf. The temperature data crosses the boundary below the ice shelf draft, and we can see how the open bay interacts with the water under the shelf.
 
In other news, I think tomorrow is the half-way point of the cruise. For those of you out there anxious to see those of us down here once again, you are beyond half-way. We left you four or five days before the cruise began and will see you much sooner after it has ended.

Ship Tracking

I hear there is a website for tracking the ship here: http://www.sailwx.info/shiptrack/shipposition.phtml?call=WBP3210.
 
I cannot verify if my map is working, but if so you can also follow us here: http://kenmankoff.com/maps/NBP09-01/

Under the Ice

Most of last week was spent sitting around Pine Island Bay doing CTDs while the AutoSub (a small autonomous yellow submarine) was exploring under the ice. It is seven meters long, powered by 5000 D cell batteries (manually inserted).
 
I haven’t mentioned AutoSub much because we were waiting to see how the project went. It has done very well, including surviving an underwater bump with some ice that left a dent on its nose and still making it home. It has done multiple missions under the ice, some of them almost 30 hours in length and up to 150km total distance. It maps the ocean floor and the bottom of the ice shelf, in addition to sampling water properties.
 
Tonight while it is getting repaired we’ve had the opportunity scout the ice conditions to the west, where we will head next once AutoSub operations are complete. We sailed for 50 nautical miles near the Thwaites Glacier Tongue at location (lat:-74.3766 lon:-105.4643). For the past two hours we have been sailing along the edge of a massive piece of Pine Island Glacier that broke off in 2007, drifted here, and has been stuck on a high bottom feature for the past few months. This iceberg is 10s of miles long and covered a large chunk of the horizon while we were still quite far away from it. Now, right next to it, it towers over us and fills our view on one side.
 
On the other side is open ocean with bits of ice containing dozens of penguins (mostly Adelie), and the occasional seal. Throughout the night we’ve sailed past hundreds of penguins.
 
The sun is getting lower each day as the earth rapidly tilts from solstice toward equinox, which means the colors are getting better. The solar minimum is still about 30 degrees above the horizon, and occurs around 4AM ship time, right in the middle of my shift.
 
 
location: lat:-74.3766, lon:-105.4643

PIG Macro

Macro view of Pine Island Bay and Glacier. Image is about 300 km across.

3D Model of PIG

Flipped Bergs

We’re still in Pine Island Bay collecting data. The bathymetry map has been filled in so we know what the bottom looks like, and from all our sailing we have most of the surface sampled at one point in time or another. We’re slowly filling in the space between the surface and the bottom with CTD samples at regularly gridded locations. This will give us a 3D view of the bay.
 
You’ve seen the photo I posted earlier of the Minke whale. Yesterday morning there was a pod of 20 or so of them that spent a few hours within view of the ship. Not close enough for any good photos, but with a pair of binoculars you could see dozens of fins at a time and blowspouts all over the place.
 
Later in the day we sailed by a massive iceberg that had rolled over. If the image is attached to this post hopefully you can see it. We aren’t sure of the scale but we estimate the ridges at about 25 feet. That puts the berg at around 600 feet long or so. These things move slowly and often in circles and it might remain here for weeks if not months and years. If we sail by it again we can get our distance with the radar, and then use a sextant or shadows or even just a ruler and parallax to get accurate measurements. Or maybe a penguin will be sitting on it for scale. Then one could start to ask and answer all sorts of interesting questions about the bottom morphology, how bergs get stuck and eventually released, how they get scraped apart from below and how they in turn change the ground beneath them…

Pine Island Glacier and Minke Whale

Adelies on Iceberg

PIG

I woke up this morning in Pine Island Glacier. We are surrounded on three sides by the towering cliffs of the floating tongue of the glacier. They rise 50 or 60 m above the water and therefore 500 or 600 m below. I’ve never seen the white cliffs of dover but I imagine they would look small and yellow compared to these. (Maybe H will take me there someday).
 
A CTD cast was coming up at the beginning of my shift. I spent the first hour doing samples, and the rest of the night should be easy. We’ll be doing bathymetry mapping swaths and no sampling, so my job will be to enjoy the view.
 
Weather: -2.5 (Air) -0.5 (Water)
Location: lat:-74.9601, lon:-101.6803
 
Bright sun, blue sky, blue water, white cliffs, some ‘berg bits and a few gigantic tabular icebergs floating in the bay.
 
In other news, someone commented on my blog! (Thanks Mom). No, the sun moving West to East is not a typo. Normally the sun moves east to west, but at night it needs to ‘reset’ to the east, so relative to you, it moves west to east around the back side of the planet. Since I’m close enough to the pole to see over it (so to speak) I get to watch the sun move in a circle 24 hours a day. After it moves east to west during my ‘day’ while I am sleeping, I watch it move west to east on the other side of the earth during our ‘night’.

Life Stinks

Yesterday we excited the ice (on the Southern side) into a polynya in the Pine Island Bay. The water turned from a clear dark blue to green. We are sailing through the most biologically productive ocean on the planet. I’m not sure but the seas here might have even more life than a rainforest. And it stinks.
 
The smell is subtle inside, but when you are working outside or with the doors open there is a strong smell of rotting vegetables.
 
In other news, land ho! We still cannot see the mainland but have passed some small islands. The islands are on the maps from satellites, but we are charting new waters and making our bathymetry maps as we go. We should see the continent (or at least the ice sheet covering the continent) within a day or two depending on our meandering path.
 
Current location: lat:-74.104 lon:-105.423
Current Temperature: -1.3C Air, 1.2C Water
Wildlife today: Billions of diatoms one Minke whale and a seal.