[M-IS10] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS10-04] Response of biogeochemical cycle and lower trophic ecosystem to the environmental change in the Southern Ocean, East Antarctica

*Naomi Harada^1,2, Maki Noguchi Aita², Takuhei Shiozaki¹, Fujiki Tetsuichi², Katsunori Kimoto², Shinsuke Kawagucci², Minako Kurisu², Kohei Mizobata³, Ryosuke Makabe⁴, Toru Hirawake⁴, Koji Sugie², Susumu Takatsuka⁵, Kazuya Kusahara², Akitomo Yamamoto², Ayumi Maeda¹, Hatsumi Nishikawa¹, Sijun Chen¹ (1.The University of Tokyo, 2.Japan Agency for Marine-Earth Science and Technology, 3.Tokyo University of Marine Science and Technology, 4.National Institute of Polar Research, 5.Sony)

Keywords:Southern Ocean, Biogeochemistry, Time-series observation, High time and special resolution Model

The Southern Ocean is famous as a high nutrient and low chlorophyll (HNLC) area with abundant fisheries resources. In East Antarctica, where the Showa Station is located, the influence of global warming was not considered to be in progress, but recently, Japanese observations have revealed that the melting is in progress, especially in the Totten ice sheet. The melting of the Antarctic ice sheet is thought to have a significant impact on the surrounding physical environment, biogeochemical cycles, and marine ecosystems by supplying large amounts of fresh water, but the links between the three are still unknown. Therefore, we try to solve two following questions: what are the characteristics of the Southern Ocean in East Antarctica as an HNLC region? And what hypotheses can we make about the mechanisms linking the physical-chemical-biological processes? The driving force of the transport of sea ice, water masses, and materials in the study area is stationary mesoscale eddies (approximately 100 km in diameter). In the eddy, a time-series mooring system equipped with water temperature (T), salinity (S), and event-based vision (EVS) sensors, current profiler, and sediment trap will be deployed. Biogeochemical (BGC) floats equipped with T, S, DO, pH, nitrate, and Chl.a sensors will also be strategically deployed around the mooring system. Using the integrated physical, chemical, and biological observation data from the mooring system and the BGC floats, we will understand the physical and chemical environments and biological production, capturing seasonal features, and will also suggest hypotheses for missing links of physical-chemical-biological processes. In terms of Q2, we will develop an integrated physical-material cycle-biological model by linking an Earth system model with high temporal and spatial resolution. This model will be run to describe the relationship between the physical and chemical environment and the response of lower-trophic level ecosystems in the Southern Ocean. Finally, we will present a future vision of the marine ecosystem-biogeochemical cycle according to CO2 emission scenarios.