Report of the observations and activities of the 61st Japanese Antarctic Research Expedition wintering party and 62nd summer party
Largest ozone hole in five years confirmed

The National Institute of Polar Research (NIPR) reported back on the observations and activities of the 61st Japanese Antarctic Research Expedition wintering party and 62nd summer party on February 15. The expedition returned to Japan in February 2021. The observations carried out by the 61st wintering party revealed the largest ozone hole in five years. The 61st wintering party and 62nd summer party worked together on observation and maintenance duties as planned, as well as completed the handover to the 62nd Japanese Antarctic Research Expedition wintering party.

The 61st wintering party (30 members) departed Japan from Narita on November 27, 2019, passing through Australia and setting sail on the Shirase from the port of Fremantle. Continuing their oceanic observations, they arrived at Syowa Station in Antarctica on December 30. Due to the novel coronavirus disease (COVID-19), the 62nd summer party (13 members) embarked on the Shirase direct from Japan, leaving Harumi Wharf on November 20, 2020 and arriving in Antarctica on December 19. The changeover with the 62nd wintering party was conducted on January 18, 2020, then the 61st wintering party and 62nd summer party left the Antarctic together on the Shirase the next day, returning to Japan on February 22. The wintering party lived for around 16 months on the ice, with their main role of continuing the basic observations that have been made for decades. The summer party stayed for the summer season, only for around four months, taking care of highly urgent research observations. In addition, the parties each took responsibility for managing facilities and installations, as well as maintenance.

The 61st wintering party observed the biggest ozone hole in five years during basic observations using techniques such as ozonesonde (direct observation by balloon), Dobson spectrophotometer (ground-based observation) and Brewer spectrophotometer (ground-based observation). The Antarctic ozone hole varied across a wide range in 2020 but in September, dramatic ozone depletion was recorded above Syowa Station and on October 17, the lowest ozone value of the season was recorded. In November, the lowest monthly ozone volume was measured since records began in 1961. From late November to mid-December, the ozone hole hit a new size record for the period. Then in late December the hole shrank rapidly, disappearing on December 28. On November 17, a polar stratospheric cloud was seen over Syowa Station, a phenomenon related to the ozone hole.

The ozone hole is in a long-term shrinking trend and is forecast to return to a pre-1980s level by around 2060. It is likely that this season's ozone hole expansion was due to the impact of low temperatures in the stratosphere, where the ozone layer lies.

Japan Aerospace Exploration Agency (JAXA) and MISAWA HOMES CO., LTD., together with the Misawa Homes Institute of Research and Development Co., Ltd. and the NIPR, also conducted testing of the Antarctica Mobile Station Unit (AMSU). The 61st expedition party transported the two AMSU units to the Antarctic, assembled them into a single station unit and (1) tested the structure for its flexibility in expanding and contracting, (2) tested its energy use for optimum efficiency and (3) tested the environmental monitoring within the station using sensors. After testing, the AMSU was transported to Dome Fuji Station, the base located deep inland at an altitude of 3800m. It will be used as a living space under the Dome Fuji Deep Ice Coring Project 3, planned for the 63rd expedition party onwards.

For 19 days from October 6, an expedition to Mizuho Station was launched with four large snowmobiles for inland use, aiming to make observations of space, air and water as well as to establish a route for construction vehicles. Along the way, the convoy gauged snow accumulation, monitored weather and created a transport route for 180 fuel drums. The team also performed repairs of the wooden sled (2 tons) used for carrying fuel drums and tested the use of a sheet sled for future journeys.

The 62nd summer party was much reduced in size due to COVID-19. The summer party in a typical year would number around 40 members. All members isolated for two weeks before departure. It was a tight schedule, but in around one month from arrival they completed transporting all the equipment required by the 62nd wintering party. They brought 1041.5 tons of equipment to the ice, more than half the weight of which was fuel. They collected 466 tons of waste to return to Japan.

The tidal observation device set up in the Earth Science Laboratory to gauge tidal movements in the Nishinoura bay since the 12th expedition was demolished. A new unit was installed in the Fundamental Observation Building and began operating on December 23. The Ionosphere Laboratory data server was moved to the Fundamental Observation Building and a test GNSS satellite wave scintillation counter was installed and commenced operation.

The Program of the Antarctic Syowa Mesosphere-Stratosphere-Troposphere/Incoherent Scatter Radar (PANSY), which is a large atmospheric radar designed to understand the role played by atmospheric gravity waves in the general circulation of the Earth's atmosphere has been dedicated to observation for the last six years in association with meteorological agencies around the world. It enables precise measurement of the troposphere, stratosphere and mesosphere above Syowa Station, so with dedicated observation it is able to capture the effect of sudden warming phenomena in the northern polar stratosphere. Dedicated observation took place this time from December 30 to January 20. It succeeded in obtaining almost continuous high-quality observation data.

The expedition also installed a new rain radar, conducted fieldwork, did repairs and maintenance of all types of unmanned instruments, and on board the ship conducted a geological study of the ocean floor, lowered and raised a submarine pressure gauge and investigated the sea water. Advance plans were made in case of the outbreak of disease, but there was no outbreak and all members returned safely to Japan.