Arctic Ocean mixing processes and vertical fluxes of energy and matter

Informations

Funding country

Norway

Acronym

-

URL

-

Start date

1/1/2019

End date

12/31/2023

Budget

1,169,238 EUR

Fundings

Abstract

AROMA is motivated by the rapid changes that are now occurring in the Arctic climate system, manifested by thinning sea ice, warming ocean and atmosphere temperatures, with consequences for the uptake of atmospheric carbon, net primary productivity, strong climate feedbacks, and dramatic implications for society. The overall objective of AROMA is to advance our understanding of the role of vertical mixing for the heat and carbon budgets of the Arctic Ocean, the role of ocean heat in changing sea ice thickness and area, and the associated feedbacks. To address this objective, AROMA participated in the international MOSAiC program to collect measurements in the water column under sea ice, as the research icebreaker Polarstern drifted across the Arctic Ocean for one year, between September 2019 and October 2020. Measurements were made by scientists participating in the drift, as well as from autonomous instruments and platforms deployed in the ice camp. The observations are analyzed together with related studies conducted under the Nansen LEGACY project, in the Barents Sea and north of Svalbard, expanding the scope and the regional coverage. In the first phase of AROMA, we participated in the MOSAiC drift. Additionally, we participated in the Nansen LEGACY physical process cruises to the Barents Sea, in October 2020 and in winter 2021, to study the dynamics of the polar front between the warm Atlantic-origin waters and the cold polar waters. In collaboration with scientists from the University of Alaska Fairbanks, we analysed data collected by ocean moorings in the Eurasian Basin of the Arctic Ocean from 2003 to 2018. These new results show the growing and spreading influence of heat associated with Atlantic water entering the Arctic Ocean and that a new feedback mechanism is contributing to accelerating sea ice loss. In 2022, we analyzed the data collected during MOSAiC. We documented the evolution of ocean turbulence under ice over a full year. We used a novel kind of ascending microstructure profiler to measure the structure of turbulence in the upper ocean up to the ice surface, which allowed us to give a detailed description of ocean-ice interactions. Combining year-round microstructure observations from MOSAiC with the numerous cruises of the Nansen LEGACY project, we investigated how far existing methods to quantify turbulence from standard observations are applicable to the unique Arctic Ocean conditions. Our observations from north of Svalbard emphasize the role of tides as an important source of mixing in the Arctic Ocean. The pathway for the energy from tides to turbulence, the magnitude and distribution of the ocean mixing rates, and the role of feedbacks between mixing rates, stratification, sea ice and the tide are key to predicting the fate of the Atlantic water in the Arctic, and the evolution of the Arctic Ocean in a warming world.