The AVLAP/NABOS 2015 Russian-US expedition ended recently. What is the essence of the program?

The AVLAP/NABOS program launched in 2002. (AVLAP is a Russian abbreviation that stands for Atlantic Waters in the Laptev Sea and NABOS stands for Nansen Amundsen Basins Observation System). At that time, the first pilot expedition took place. The program's goal is to perform long-term monitoring of the dissemination of warm Atlantic waters in the Arctic Ocean.

I should explain straight away why this is important. The Arctic Ocean's climate is to a large extent predetermined by the transfer of warmth from temperate latitudes in the atmosphere and ocean. The most massive transfer of warmth in the ocean is associated with the flow of Atlantic waters, which is a continuation of the North Atlantic current. Atlantic waters penetrate the Arctic Ocean and contribute to the formation of the ocean's warm layer of water, which is separated from the ice cover by cold surface waters.

Since the influence of heat flows from temperate latitudes is important for the Arctic climate (in the water and atmosphere), any changes that occur in this system require serious study. This is in fact the objective of the AVLAP/NABOS program. I'd like to stress that it originated as a comprehensive program. In other words, project directors always sought, to the maximum degree possible, to get researchers involved in these expeditions provided they contribute their ideas to the research project.

How big was the expedition this year? What countries were represented?

This year, there were 40 members from seven countries: Russia, the United States, UK, Poland, Germany, South Korea and New Zealand. The largest number came from Russia. By tradition, the expedition was aboard a Russian ship. This time it was the Akademik Tryoshnikov.

Usually, in addition to an expedition, we organize a summer school for undergraduate students, young researchers and postgraduate students from different countries. So our team would be joined by some 15 students and four or five professors. Participants in the summer school would listen to a series of lectures and took a course of training at the expedition's research units (detachments). This time, unfortunately, for a number of reasons, the summer school could not be organized.

You have a multinational team. Is it difficult to find mutual understanding?

The specifics of such expeditions are that people can speak different languages but everyone understands one another on a different level, as it were, as they are all researchers doing more or less the same thing. And, of course, this makes communication easier.

Naturally, in selecting Russian participants, we pay attention to their proficiency in English. When people work side by side, in any event, they have to communicate constantly on professional issues. As a general rule, mutual understanding is established quickly and we have never had any problems with communication on a working level.

What work was conducted this year?

The main task this year was to raise and install submerged standalone buoy stations. I'll briefly explain what this is and why it is important. The fact is that  weather conditions in the Arctic are rather harsh. It is tough to carry out research here even in summer, while in winter, the situation becomes even more difficult.

Ice makes expeditions virtually impossible. The only exception is our North Pole drifting stations. However, there is a serious problem with these stations. A station drifts, say, as it follows the wind. Meanwhile, we often need to conduct research not where the wind blows but where new research data can be obtained.

In this connection, we have a gap in our winter observations in the Arctic Ocean. There are several ways to fill this gap. One is to install long-term standalone stations that take measurements and record information on an electronic memory card for several months, sometimes even several years. Another method is to use drifting buoys. They are mounted on an ice floe and drift like our North Pole stations, transmitting data to consumers by satellite. However, we have the same problem here as I mentioned earlier. Our focus in this program was on specific warm water transfer zones, so we used the first method, i.e., the installation of stations.

Basically, a standalone station is a cable with a one-ton anchor (metal or concrete block) that is attached below. On top, the cable is connected to a metal ball with a diameter of approximately a meter and a half. The ball is empty so it stays afloat. An array of instruments are attached to the cable that take measurements and record information on their memory cards for a lengthy period of time. Because of the floating ball, the cable is always in a vertical position, despite the current.

The problem is that data cannot be transmitted by satellite in real time, as the top ball is located at a depth of about 50 m from the ocean surface. If it was on the surface, the station would be inevitably dislocated by floating ice.

During the expedition, the structure is installed at a specified point. The instruments take measurements offline over a set period (before 2013, for one year and now for two years). Information about the water temperature, salinity, hydro-chemical parameters and dynamics is continuously recorded on memory cards. Two years later, the vessel returns to the installation point, finds the station, raises it to the surface and downloads the information, whereupon it is processed. Such is the algorithm.

This year, the station program was intense as never before. We raised eight of nine stations. One we could not find. We installed 13 new stations. To compare, in previous expeditions, between 2002 and 2009, we used to raise about three stations and install four or five.

I'd like to note that we had a very strong technical group. It would seem that ascent and descent operations are simple and easy. Not so. There are a limited number of specialists, top-notch technicians who are able to carry out these operations in the first place. I'm glad that such professionals have been cooperating with us for years. You see, science is very important, but we need information for science to advance and it takes a lot of effort to obtain his information.

How do you choose the place to install a station?

We know the oceanographic conditions in different seas, including the seas of the Arctic Ocean. That is to say, we have some idea about the location of the main stream of the Atlantic waters we want to study. It is known that they pass along the continental slope approximately 2 km above the seabed. There are places where this stream forks. This is related mainly to the presence of deep water canyons. (Narrow depressions in the ocean floor with depths of over 300 meters located in the transition zone between the continental shelf and the deep ocean. — Ed.). Usually, there are several streams in canyon areas that interact with one another, as well as with other waters.

These are important, key places where the Atlantic water current, as it moves in the general direction from west to east, transforms the most. To get a general picture of how these waters are distributed, how they interact with other water masses and how they impact the ice and atmosphere, we install stations in such key places (because, unfortunately, it is impossible to install them everywhere).

This is not the first year climate change research has been conducted as part of the Russia-US program. Based on your observations, is it possible to predict what will happen with the Arctic climate in the next several years?

You know, I will probably not venture to state unequivocally what the Arctic climate will be in the foreseeable future. Nevertheless, I can put forward certain hypotheses, which I believe are well-substantiated.

Some time around 2000, the melting of ice in the Arctic Ocean accelerated in summer. It is important to note that at the end of the summer season, the open water area has not been growing from year to year, but showing multidirectional changes, with a general trend towards ice shrinking. For example, the absolute minimum of the summer ice area was observed in September 2007, after which partial recovery was recorded. The next absolute minimum happened in September 2012. In 2013-2014, again, there was partial recovery, but in September 2015, the ice area effectively returned to the September 2011 level. That is to say, this year, at the end of summer, the ice area was the fourth narrowest after 2012, 2007 and 2011. From my perspective, the most reasonable hypothesis is that climate is affected both by greenhouse emissions and by a succession of cycles.

Regarding changes in the water column structure, perhaps the most interesting result that we noted both during the last AVLAP/NABOS expedition (in 2013) and this year is that because the ice melts faster, a larger area of the ocean surface in the Arctic remains ice-free for a longer period in summer. What are the implications? There is more intense accumulation of solar heat in the upper ocean layer. As a result, ice formation in such areas is delayed, as the ice is not formed until the water temperature near the ocean surface drops to a freezing point, which is prevented by the excess heat that is stored during the summer season.

Recently, we observed such changes in the northern parts of the Kara and Laptev seas, where a massive layer of warm surface waters formed as a result of the intense accumulation of heat during summer. It will definitely influence the climatic condition of the ocean-ice cover system as a minimum for next year and maybe even for a longer term.

Are there plans to conduct such expeditions in the future?

As I said earlier, this year we installed 13 stations. So they will have to be raised in two years. Otherwise, our work makes no sense. Let's hope that the new stations will successfully measure and record a large amount of valuable information. In short, raising these stations and downloading their information is the main purpose of the 2017 expedition. Of course, further research depends on a lot of factors, including financial factors. We would like to continue this monitoring because amid rapid climate change continuous information about the status of the system helps assess the pace of change in good time and make a well-substantiated forecast for the future. In other words, such research projects only make sense if they are conducted over a long period as the most important thing is to understand the trends of ongoing changes, not just to measure something once.

Unfortunately, the agencies that provide funding for research projects, as a general rule, dislike (regardless of the country in question) long-term programs because they always want a quick payoff. You can understand them, of course, but from the standpoint of climate science, things are far more complicated. Such long-term research projects are especially valuable as they provide the most objective information. When we try to understand what is happening to the climate we certainly need long-term monitoring. I hope this understanding will help continue the international AVLAP/NABOS program.