The U.S. GEOTRACES team is at 85 °N and ice cover is increasing. The captain has slowed our speed from 10 to 5 knots and fired up a second engine. As we move north into thicker ice we will continue to lose speed and require more power. The crunch of breaking ice underneath the bow is audible throughout the entire ship. There is no ebb and flow to the movement, just an unstructured shaking as we pass through different layers of ice.
At our current location >90% of the surface ocean is covered by ice, however, we have yet to encounter a floe large enough for safe sampling. There are still large swaths of open water and patches of thin first year ice, not the thick multiyear sheets we expected to encounter at this latitude. The Coast Guard will determine when the ice is thick enough for us to exit the ship, and survey the floe before the science team moves on. In preparation for sampling we have had a number of planning and safety meetings. Polar bears present a risk to scientist working on the ice and the Coast Guard will have three armed personnel (two on the ice, one on the bridge of the ship) to protect us. During our safety briefing the Coast Guard provided the following need-to-know polar bear facts:
- Polar bears sit at the top of the Arctic food web and are excellent hunters
- Adult males weigh up to 1700 lbs, females 550 lbs
- They can run up to 25 mph for short distances
- Their sense of smell ranges over one mile
- Polar bears will take a bite out of anything they think is food, including humans
If a polar bear is spotted we will drop everything and head back to the ship. Shooting a bear is a last resort that will only be taken to save human lives. If we have to abandon our gear on the ice the bear will have free range to toss around samplers and sink our supplies.
On August 25 during a sampling event, one curious polar bear spent 30 minutes checking out the Healy. He jumped and swam between ice floes just 50 ft from the ship, nose in the air trying to decipher all the foreign smells that emanate from a Coast Guard ice breaker filled with 120 humans.
Before reaching 90 °N we will occupy our first crossover station – the German GEOTRACES team onboard a separate icebreaker will sample the same coordinates shortly after we depart to compare results and assess the accuracy of our measurements. Our estimated time of arrival at the North Pole is early morning September 4th. We will spend around 24 hours sampling water, particles, ice, and sediment from one of the least explored regions of the world in terms of ocean chemistry.
Check out http://icefloe.net/Aloftcon_Photos/ for hourly updated photos of our location from the USCGC Healy!
Ice cover has been increasing as we near the top of the Earth. Below are images from August 17 at 74 °N, August 19 at 75 °N, and August 26 at 84 °N (top to bottom).
The USCG Healy sampling in the marginal ice zone.
Sea ice accumulates in the Arctic Ocean during the winter when the tilt of the Earth’s axis leaves the top of the world in complete darkness. Ice coverage reaches a maximum in mid-March and can cover up to 80% of the Arctic Ocean. The sun begins to rise above the horizon by the end of March, days lengthen and the ice begins to melt. Sunlight persists for 24 hours during the summer and ice coverage reaches a minimum in mid-September before the darkness returns. The dates of the U.S. Arctic GEOTRACES expedition were selected to capture the mid-September ice minimum, increasing our chances of breaking through to the North Pole.
This week we have been sampling the marginal ice zone where the edge of the ice sheet has started to melt. Our original plan was to approach the North Pole from the east in the Canada Basin and return through the western Makarov Basin, however, satellite data from the National Ice Center (NOAA) shows ice as thick as 10 ft still occupying the east. The captain must carefully budget our 1.2 million gallons of fuel and breaking through thick ice this early into the trip would surely cut our time short. We have decided to reverse the transect and approach from the west, with hopes that the eastern passage will be clear of ice for our late summer return.
The Healy is in open water with large chunks of ice, or floes, of varying size floating at the surface. On Thursday we saw a polar bear closing in on the ship from about one mile away. I watched through binoculars as the bear jumped over ice floes and started slowly swimming towards the ship, we had to re-position before he got any closer.
Large drifting ice floes add an extra challenge to our sampling efforts. Earlier this week one of our water samplers got caught on a floe that was slowly drifting away from the ship with a surface current. The captain backed the ship up to the floe while the crew leaned over the side with large metals poles to break up the ice. The sampler was successfully recovered with minor damage to the wire. Drifting ice will continue to be a threat, especially as travel north and encounter larger floes.
The winch used to raise and lower our main water sampler is not doing well in the cold weather. On Wednesday the Coast Guard made a special air delivery of supplies to help keep the motor running as temperatures continue to drop.
The chemistry of the ocean has a story to tell and with each sample of seawater we reveal new pieces of information – where the water has been, how old it is, what it has gained from the atmosphere or coast, what it has lost. Nutrients and trace elements give clues to how much life the water can support. Particles slowly sinking to the bottom are a mixture of microscopic organisms both dead and alive, a conglomeration of materials from land and ocean.
Particles filtered from seawater pictured under a microscope. Both images are the same sample: on the left fragments and whole cells of marine phytoplankton are pictured, on the right with no light only living cells containing chlorophyll glow. Image from Sara Rauschenberg, Bigelow Laboratory. For more on particles check out SeaPeteRun.tumblr.com.
The Arctic Ocean is the smallest ocean basin in the world with remarkably complex features. Water in the Arctic is a mixture of seawater from the Atlantic and Pacific Oceans, and freshwater from major rivers that drain into the basin. Warm, salty water from the North Atlantic flows into the Arctic near Greenland, and cold, lower salinity water flows in from the Pacific through the Bering Strait between Alaska and Russia.
The Arctic water column is stratified – salty water from the Atlantic does not mix evenly with Pacific water or freshwater from rivers and instead settles in different density layers. The surface layer has the lowest salinity from mixing with river water and melting ice. As the surface layer freezes into sea ice, salt is ejected into a deeper layer called the halocline. The halocline is mostly Pacific water near the Bering Strait (where we are sampling) all the way to the North Pole. In the eastern Arctic near Greenland the halocline is mostly Atlantic water. The deepest layers across the entire Arctic Ocean are made of mostly dense, salty Atlantic source water.
Major rivers flow into the Arctic Ocean from Alaska, Canada, and Russia and form large continental shelves that amount to 30% of the basin’s surface area. Continental shelves are extensions of land underlying up to 200 meters of seawater that form when rivers flowing into the ocean deposit sediment. We have spent the last week sampling water overlying the Alaskan and Chukchi shelves; sediments can be a source or sink of different trace elements and this signature can be carried out to sea with currents.
Water from the Pacific and Atlantic Oceans flows into the Arctic Basin. Image from Woods Hole Oceanographic Institute. Check out this link for the interactive image.
On Sunday afternoon August 16, the USCGC Healy passed through the Bering Strait and crossed the Arctic Circle (66°33’45.7 N). Those who have previously crossed the Arctic Circle are considered “polar bears,” and Coast Guard members with this distinction were allowed to wear special red shirts to celebrate the day, a splash of color added to their everyday navy blue uniforms. Sailing over major latitudinal lines is a right-of-passage that involves a secret initiation ceremony, most especially for equator crossings.
We sampled two stations within the Bering Strait along the border of the United States and Russia. Seawater flows through the strait into the Chukchi Sea which borders the Arctic Ocean and it’s important to characterize this water as it flows north. We do not have permission to sample Russian waters but stayed close enough to the border to capture water flowing through the middle of the strait. Pictured below, the ship is approaching the Diomede Islands in the center of the 51 mile wide Bering Strait – Big Diomede on the left is owned by Russia, and Little Diomede on the right is owned by the United States.
Steaming towards the Diomede islands – Big Diomede Island (left, Russia) and Little Diomede (right, U.S.)
Our path through the Bering Strait is outlined in red.
The USCGC Healy sailing out of Dutch Harbor, Alaska into the Bering Sea (August 9, 2015).
And we’re off!
The U.S. GEOTRACES Arctic expedition departed Dutch Harbor on August 9th onboard the USCGC Healy. Shortly after departure we had our first safety drill. Everyone onboard has to practice putting on immersion suits which are kept on the boat for an emergency situation that would force us to abandon ship and jump into the water. The suits are bright orange with a flashing light and whistle, and the back has an inflatable pouch for flotation. There is a rubber cap that goes over your head and hugs tightly around the neck to prevent water from flooding the suit. The shoulders of the suits have clips to attach to a neighbor, in the water we would hook our suits together and form a giant circle of bodies that would be easier to spot from the air.
It takes me about one day to get my sea-legs with the help of some medication to prevent motion sickness. After day one I am medication free, unless we run into harsh weather (>20 ft seas make me slightly queasy). Everyone handles seasickness differently. I am lucky to be able to adjust to the motion, but others, even those who frequently go to sea will continue taking medication throughout the cruise. Over-the-counter Bonine and Dramamine are the most common medications used onboard. For extreme motion sickness there is the prescription-only “Coast Guard Cocktail” which is a dose of promethazine (a mild sedative) for anti-nausea, paired with ephedrine to keep you awake. Fortunately, the Bering Sea has been kind to us this week with calm seas and fair temperatures between 40–50 °F.
We had two days to test our equipment before arriving at our first station Wednesday morning. During those two days we had a major mechanical malfunction, broke the frame of our water sampler, had a minor deployment related injury, and some hiccups in the lab. But, with some replacement parts, on-site welding, a few stiches, and some tender loving care to our delicate laboratory instruments, as is well. The biggest challenge of doing science at sea is the isolation. We have only the supplies that we brought and the people onboard to solve the multitude of problems that arise.
Next week we will pass through the Bering Strait and enter the Arctic Ocean. At our current latitude (60 °N) there is about 19 hours of daylight and as we travel north the days will get longer. Stay tuned as we transition from open water to sea ice!
Dr. Phoebe Lam from the University of California, Santa Cruz and her team prepare to test custom designed pumps. The pumps are manually attached to a wire and lowered into the ocean where they push thousands of liters of seawater through a multitude of filters to collect marine particles.
Our current position in the Bering Sea, 179 °W 60 °N.
Smooth sailing in the Bering Sea this week.
I will be doing some cross posting on a blog with the Huffington Post during the next few months. Check out my first piece on mercury in the Arctic and the upcoming GEOTRACES cruise: http://www.huffingtonpost.com/katlin-bowman/oceanographers-board-a-fl_b_7921510.html
The U.S. Coast Guard’s Healy Icebreaker in port at Dutch Harbor, Alaska.
I arrived in Dutch Harbor on Tuesday in a 30 passenger propeller plane. Scientists from all over the United States have been trickling in this week to prepare the Healy for our upcoming Arctic GEOTRACES expedition. Dutch Harbor is located on Amaknak Island, part of the Aleutian chain stretching southwest from Alaska. The trip from Anchorage to Dutch Harbor takes 3 hours with a mid-way re-fueling stop on King Salmon Island. The pilot had little faith that the fog would lift for our landing, but we got lucky. The previous day strong cross winds forced a plane with a group of scientist to turn back to Anchorage, 6 hours in the air just to land in the same spot. Every carry-on bag, checked luggage, and passenger has to be weighed and when the plane is too heavy, checked bags are left behind. The whole science party has safely arrived in Dutch Harbor but some bags and packages and still coming in.
There is little cell service or internet on the island, a perfect transition to life at sea. We are staying at the Grand Aleutian hotel with a mixture of fishermen and Shell employees. After landing on the island I rented a car to drive around and explore, 20 minutes later I was back in the same spot. Amaknak Island is small, but beautiful and alive with wildlife. There are big rolling hills covered with greenery and wild berries, bald eagles flying overhead, dozens of spouting whales swimming in the bay.
It’s been a busy week in port getting shipboard laboratories and sampling equipment ready for our first stations. This involves mixing chemicals to make reagents, moving gas cylinders, and getting our analytical detectors turned on and running smoothly. Everything inside and outside of our labs has to be secured and tied down by the time we leave port and the science party has been busy with cranes and forklifts moving everything to its proper place. The Healy will leave port August 9th with 51 scientist and steam into the Bering Sea for the first stations of Arctic GEOTRACES.
Thick fog trapped between the hills on Amaknak Island can make landing difficult.
Exploring Amaknak Island I found bunkers embedded into the hillside. Dutch Harbor was attacked by the Japanese during World War II.
Moving gas cylinders that will be used to run laboratory instruments during the U.S. GEOTRACES Arctic expedition.