Research topics

OVENS: Overturning in the Nordic Seas

The aim of the OVENS project is to fundamentally advance our understanding of the coupled ocean-atmosphere climate system in the Nordic Seas and to integrate and quantify this insight within the framework of the Atlantic Meridional Overturning Circulation in the present and future climates. In order to contribute the project, I will quantify horizontal and vertical ocean circulation in the Nordic Seas and define its role in the climate system primary analysing historical hydrographic data.

• A link to OVENS project webpage.

• An article published by UK independent on 24 November 2020.

• An article published by Bjerknes Centre for Climate Research on 23 November 2020.

• A paper published by Nature Climate Change on 23 November 2020.

ARCGATE: Maximizing the potential of Arctic Ocean Gateway array

The ARCGATE, funded as a EU Marie Curie project, has integrated all individual mooring arrays across the Arctic boundary. We have quantified time variability of both horizontal and vertical ocean circulation and associated heat and fresh water (FW) transports over the years 2004-2010. The monthly volume transport in Arctic major four gateways has been quantified (Figure 1). The associated total boundary heat flux, as a sum of oceanic and sea ice contributions, is 180±57 TW (mean ± standard deviation for the 68 months). That of FW flux is 156±91 mSv. The diagnosed time series provide a benchmark data set for the validation of numerical general circulation models of the Arctic Ocean and air-sea surface heat and FW fluxes estimates from atmospheric re-analyses.

Figure 1: Monthly gateway volume transports (m3s-1) and its mean seasonal cycle. The time series is from October 2004 to May 2010.

• A link to ARCGATE project webpage at ASOF website.

• A link to ARCGATE project webpage at AWI website.

• A poster presented at ASSW meeting, Prague, Czech Republic, 3-7 April, 2017.

• A slide presented at ASOF meeting, Sopot, Poland, 20-22 March, 2017.

• A short film explains why we monitor the Atlantic Ocean at NACLIM website.

Arctic Ocean Heat and Fresh water budgets

Arctic Synoptic Basin-wide Observations (ASBO) project and The Environment of the Arctic: Climate, Ocean and Sea Ice (TEA-COSI) project both aim to better quantify and understand the Arctic ocean's import of heat, export of fresh water, and storage of both. I approach this scientific challenge by closing the Arctic Ocean with ship-based CTD measurement of temperature and salinity and mooring measurement of velocity under an international data sharing agreement. First quasi synoptic heat and freshwater budget of the Arctic Ocean in summer 2005 was obtained during ASBO project (Tsubouchi et al., 2012). A first full annual cycle of the pan-Arctic Ocean during summer 2005 and summer 2006 has been quantified under TEA-COSI project (Tsubouchi et al., in review).

Figure 2: locations of data across the Arctic boundary in summer 2005: ship-based CTD (red), mooring (blue), NEMO output (green).

• A paper published by JGR-Ocean on 31 January 2012.

• A poster presented at the 15th annual AOMIP meeting, Woods Hole, USA, 1-4 November, 2011.

• A presentation presented at the ICARP III meeting, Toyama, JAPAN, 27-30 April, 2015.

Spatial structure and temporal variability of Subtropical Mode Water (SPMW) in the world ocean

I aimed to understand dominant factors to control temperature, salinity and density stratifications in the western part of the subtropical gyre in the world ocean during my phD. I approached this question by comparing thickness of SPMW based on climatological temperature and salinity data (WOA 2001, Hydrobase), volume transport of western boundary current based on literatures and strength of winter cooling based on reanalysis data (ERA-40) in each basin. I also gained our understanding of SPMW in the South Pacific Ocean and in the Indian Ocean.

Figure 3: (a) locations of defined STMW in each basin and (b) their TS relation ship.

• A paper about STMW in the South Pacific Ocean published by JPO on October 2007.

• A paper about STMW in the Indian Ocean published by Ocean Science on January 2010.

• A paper about comparing STMW in the world ocean published by Frontiers in Marine Science on December 2016.

(last updated 2021.11.21.)