Antarctic UAVs

17 February 2020

In my previous blog posts I’ve talked about my trip so far but haven’t given any details about the research that Gina and I will do once we reach the Polarstern. Before I discuss that I do want to give an update on our progress towards the Polarstern. 

We’re still in transit to the Polarstern and the MOSAiC ice camp. The Polarstern is currently just north of 88 deg N latitude and we are at 85.8 deg N latitude. A few days ago we crossed from first to second year sea ice. New sea ice that forms in the winter is called first year ice and tends to be thin and not as strong as ice that survives from one winter to the next. While we were in the first year ice we were making reasonable progress towards the Polarstern – about 50 miles per day. Since we reached the thicker and stronger second year ice our progress has slowed a lot. We’ve only been traveling 10 or 15 miles per day. At this rate of progress it will take us more than a week to reach the Polarstern and we’ve already been sailing for almost two weeks. 

The expectation when the expedition was planned was that it would take about two weeks for the Russian icebreaker to reach the Polarstern. Our slower than expected progress is due to the lack of leads, or cracks in the ice, which can allow the icebreaker to travel much faster than if it is breaking through thick ice. The ice we’ve been traveling through the last few days is between 4 and 6 feet thick. Even thicker ridges, where different ice flows have collided and buckled up, can be 10 or more feet tall. To get through this thick ice our ship has to go back and forth over the same stretch of ice several times to slowly break the ice down and create a passage.

A few days ago we had a storm with strong winds and blowing snow. Since we spend almost all of our day inside, other than short periods when we go out to get some fresh air, the weather doesn’t impact us too much. The sea ice damps any waves so even in strong winds the only motion of the ship that we feel is from running over the ice. The temperature has been around -10 deg F but during the storm the temperature rose to just above 0 deg F. In the wake of the storm the temperature dropped to -25 deg F. Yesterday, the sky cleared in the wake of the storm and we were able to see an orange glow from the sun on the southern horizon near solar noon while stars and planets were visible in the still dark sky above our ship. 

Everyone on board is getting a bit stir crazy and is anxious to reach the Polarstern so they can start doing the research they had planned for this leg of the expedition. For Gina and I our research will involve flying small unmanned aircraft (drones) to study the lowest 1 km (3000 feet) of the atmosphere. Our drones will measure air temperature, humidity, wind and pressure and will also measure the intensity of turbulence in the atmosphere. We want to collect this data to see how the lower part of the atmosphere changes in response to changes in surface conditions, like different ice or snow thickness or the presence of open water in leads, as well as changes in things like cloud cover. 

The lower part of the atmosphere, where we will be flying our drones, is the part of the atmosphere that allows energy, moisture and momentum to be exchanged between the underlying surface and the rest of the atmosphere. These exchanges are important because they help determine how much ice melts or freezes during the year, what direction the ice will drift and how warm or cold the atmosphere is. As the Arctic has warmed over the past several decades the sea ice has become thinner and provides less insulation between the ocean and the atmosphere. We are interested in seeing how this thinner ice impacts the exchange of properties between the ocean and the atmosphere and we’ll compare our observations with data that has been collected on previous expeditions, decades ago, when the Arctic ice was much thicker.

Once we reach the Polarstern our first task will be to find all of the cargo we had shipped to the Polarstern before it left Germany last September. We have 15 DataHawk drones, several other drones that will be used by our teammates on later legs of the expedition, spare parts, batteries and chargers and even a tent that we’ll use as our base of operations on the ice floe waiting for us on the Polarstern. We’ll need to assemble and test a few of our DataHawks before we do any flights. We will also need to setup an area on the ice floe where we can do our flights. We’ll put up our tent there and that will serve as our base of operations on the ice and will allow us to get out of the cold wind between flights. 

On a typical flight day we’ expect that we’ll go out to our flight area on the ice right after breakfast. We’ll do 2 or 3 flights in the morning. Each of these flights will last about 45 minutes and will be limited to the lowest 1 km (~3000 feet) of the atmosphere since it becomes too difficult to see our small drone if it is much more than 1 km away from us. During the flight the drone will spiral up and down between the surface and 1 km altitude collecting data about how temperature, humidity, winds and turbulence change with height in the atmosphere. How these properties change with height gives us information about how much exchange is taking place between the atmosphere and the underlying surface. After our morning flights we will return to the Polarstern for lunch. We’ll then do another 3 to 5 flights in the afternoon before returning to the ship for dinner. 

While we are on the ice floe doing our flights one of us will have a radio control that can be used to control the drone when it is being flown in manual mode, just like a model RC plane. The other one of us will have a laptop computer that is running ground control software that communicates with and can control the drone when it is in autopilot mode. Gina and I will take turns filling both of these roles during the expedition. In addition to controlling the plane we will need to watch the airspace where we are flying for helicopters and tethered balloons (sort of like a blimp that is anchored to the ground on a long line) so we can avoid them. We’ll also be in constant radio contact with the bridge of the ship so we can let them, and the rest of the scientists, know when we are flying and we can be told when the helicopters are taking off or landing on the ship. During the day, while we are on the ice floe, we will also need to recharge batteries after each flight and download and begin processing data from the DataHawk. The DataHawk transmits some data to our ground control laptop while it is flying, but most of the data is recorded on a microSD card. 

After dinner we’ll have a daily science meeting with all scientists on the ship so each of the science groups can plan and coordinate their activities for the next day. We’ll also have some final data processing to do and will make some plots of the data we collected during the day. All of this data, and the plots, will be stored on a central data server on the ship so the other scientists onboard can access our data. One of the benefits of a large research expedition, like MOSAiC, is the wide range of data that is collected. We will use data from several other science groups to help us interpret the data we collect with our drones.

But, before any of this happens, we need to get to the Polarstern. Hopefully my next blog post will be from the Polarstern.

John