2016 marks the 60th anniversary of Japan’s Antarctic Expedition. Antarctica is an important point to learn about global climate change and history. What kind of achievements and dramas were there in the history of observation for 60 years? On January 23, I participated in the lecture “The Age of Shirase” by the Antarctic Alumni Association, which was held at the first Antarctic icebreaker “Shirase” anchored at Funabashi Port. The Antarctic Alumni Association consists of members of the Antarctic Research Expedition, the Maritime Self-Defense Force, and successive members who went to Antarctica. At the venue, such members gathered, including the former captain Shirase and the former director of the National Institute of Polar Research. There were six lectures in all, but this time I will introduce two of them, the particularly big topics achieved by Japan’s Antarctic Expedition.
Discovery of ozone hole
From September to October, which is the spring of Antarctica, the amount of ozone over Antarctica decreases, and a part of the ozone layer becomes thin like a hole. This is called an “ozone hole”. In the ozone hole, the barrier of the ozone layer that absorbs ultraviolet rays from the sun is not fully exerted, and harmful ultraviolet rays reach the ground as they are, so there is concern about adverse effects on living organisms.
Koji Matsubara, who participated in the Antarctic observations as a member of the 21st, 29th, and 46th observation teams and conducted meteorological observations, says that Japan’s steady observations have greatly contributed to the discovery of the ozone hole. The name “ozone hole” was given, and it was not until 1985 when Professor Joseph Ferman of England announced the observation results in Antarctica that the contribution of CFCs to its formation was suspected. On the other hand, ozone observation in Japan began in 1955 at the High-Rise Weather Station in Tateno, Ibaraki Prefecture (currently Tsukuba City), and in 1960 in Antarctica.Dobson spectrophotometer* 1 In addition to the observation by Ozone Sonde from the 7th 1965* 2 Observations have been introduced and are ongoing to this day.
* 1 Dobson spectrophotometer: A device that measures the total amount of ozone in the atmosphere. Observation is made by utilizing the fact that the degree to which ultraviolet rays in sunlight pass through the ozone layer and are attenuated differs depending on the wavelength.
* 2 Ozone sonde: A rubber balloon equipped with an ozone measuring device. This is fried and the amount of ozone in the sky is measured.
Shigeru Chubachi of the 23rd Corps has long discovered that in the spring of Antarctica, the amount of ozone that would normally increase in the stratosphere 15 to 50 kilometers above is extremely low. At the beginning of the observation, Mr. Tadabachi suspected that the equipment was out of order due to the strangeness of the observation results, and he said that he had inspected it many times. In 1984, he also announced the observation results at the International Ozone Symposium in Greece. Matsubara emphasized that although it is now known that the amount of ozone in the stratosphere has decreased since the latter half of the 1970s, only Japan continued to observe during that period. It should be said that it was very meaningful to have been observing continuously since the 1960s to compare the data before and after the appearance of the ozone hole.
Mr. Matsubara’s lecture ended with the following message from Mr. Susan Solomon of the United States, who won the Blue Planet Prize, which revealed the mechanism of ozone hole formation in Antarctica for the first time in the world.
“I was very impressed by the fact that Syowa Station scientists have been measuring ozone weekly and weekly since 1960. Looking at all the data for October of all years, it is a kind of’knowledge. It can be said that it was a river of knowledge ”(quoted from“ Global Environment Research Center News Vol.15 No.10 ”January 2005)
The steady accumulation of data has led to important discoveries for global environmental conservation. At the time of observation, we would not yet know what the data showed. Nevertheless, I would like to pay tribute to all the members of the observation team who have continued to make steady observations.
Ice sheet excavation drama
Antarctica is an ice continent, made up of 3,000 meters of ice on a bedrock at an altitude of about 800 meters. At the highest point is “Dome Fuji Base”. At an altitude of 3,810 meters and a minimum temperature of minus 79.7 degrees Celsius, it is one of the harshest environments in Antarctica.Here, as the “ice sheet dome deep excavation plan”, the ice sheet is dug and the core* 3It is expected that the world’s oldest ice could be extracted by successfully excavating 3,035 meters in 2007. So why dig an ice sheet?
* 3 A tubular pillar excavated as a core / research sample. The core obtained by excavating the Antarctic ice sheet is called the “ice core”.
The Antarctic ice sheet is the result of a warm, low-latitude atmosphere being carried to the polar regions and the water contained in that atmosphere frozen. Various substances that were once in the atmosphere are frozen and stored in the ice sheet. For example, changes in carbon dioxide (CO2) concentration in the pre-ice period, the age of large-scale eruptions, and the transition between cold and high interglacial periods, a past not left in other regions. You can know the changes in the environment.
Nobuhiko Azuma, the current president of Nagaoka University of Technology, who participated in the “Ice Sheet Dome Deep Drilling Project” as the 30th and 36th squadrons, talked about the road to the success of the deepest drilling in 2007. The deep excavation drill developed by Japan has a cylindrical shape with a length of about 8.5 meters, and digs while putting antifreeze into the excavation hole. It is said that this drill has been evaluated worldwide and the technology has been adopted in Europe. Currently, an improved 12.2 meter long drill is used, which boasts the highest level of drilling capacity and speed in the world. However, it seems that there was a great deal of trouble before these drills were made.
The Japanese team started developing deep drills in 1988 and conducted the first drilling test the following year. However, when digging a few centimeters, the ice got stuck in the drill, and each time I was forced to dismantle and remove the ice, the digging target was 100 meters, but in the end I could only dig about 10 centimeters that year. People around him blamed him for saying, “Will the excavation plan work as it is?” And “Why can’t I dig this?”
In response, in 1991, he participated in a camp at the bases of American and European teams in Greenland to develop drill technology. This is to study Western techniques and to train in an environment that is more accessible than in Antarctica. Members of Switzerland and Denmark, who had advanced drilling technology at the time, often visited drills with completely different designs from their own countries. The construction of Dome Fuji Base was carried out almost at the same time while advancing the technological development of the drill. In 1996, it succeeded in excavating 2,500 meters. Looking back on the fact that only 10 centimeters could be excavated at the beginning of the plan, a tremendous technological leap took place in just seven years.
After developing its own drill and building a base, Japan is now at the forefront of ice sheet drilling. There is a wide range of research related to ice sheets, such as exploring life that can live in extreme environments as well as knowing past environmental changes. The oldest ice that has been excavated so far is said to be 800,000 years old by the Italian-French joint team, but the 3,035 meters of ice that Japan excavated and obtained may be the global environment before that. It may be a clue to know.
The past and present of the Antarctic research
A topic that should be noted in the future is the “Pansy Project (Program of the Antarctic Showa MST / IS radar)”. In order to help predict global warming and the size of the ozone hole, the entire atmosphere up to 500 kilometers above the sky will be observed with radio waves emitted from radar. This project, which has 1,000 antennas on the scale of Koshien Stadium in Antarctica and captures the atmospheric circulation that has not yet been elucidated, such as the rapid temperature rise in the polar region, started full-scale observation in 2015. The Pansy Project will be an important project to monitor future changes in the global environment in collaboration with Antarctica and atmospheric observation points around the world. In addition, Japan can be said to be a top runner who studies and observes global climate change, organisms, and meteorites in Antarctica. The Antarctic Research Expedition started in 1956, when Japan had not yet joined the ranks of developed countries. Japan’s current position is due to the people who have been constantly observing in Antarctica, despite the lack of technology and supplies. While expecting the research results of the Antarctic Research Expedition, which will become more and more important in understanding the global environment in the future, please think about the hardships and successes of the great ancestors of the past.
Science writer Moeko Tabata