Role of Freshwater in Polar Ocean Climate Change and Global Linkages

Fresh water is a key player in the polar oceans setting stratification and water mass properties. In both hemispheres, export and transport of fresh water—liquid and solid— driven by the large-scale ocean and atmospheric circulation has a tremendous influence on branches of the meridional overturning circulation. Fresh water processes are strongly affected by global climate change. The fresh water-associated feedback via the atmosphere and various ocean pathways are changing.

The Arctic and the Southern Ocean are different in many ways, yet, there are similarities: the circulation is influenced by changes in regional fresh water either from river runoff or ice melt. This is exemplified by variations in the salinity-induced stratification, in turn influencing ocean circulation. In the generally quiescent Arctic with an overall strong halocline in the basin, few hotspots modify even intermediate water masses. The relative “freshness” of water (and sea ice) exported to the subpolar North Atlantic and Nordic Seas plays a key role in water mass transformation in those regions. In the Antarctic marginal seas fresh water fluxes tightly related to sea-ice formation shape strongly differing ocean conditions, which define the potential to melt ice shelves and the “flavour” of dense water masses feeding the deep overturning circulation. 

To date, many of these processes are not well represented in model simulations involving the ocean. State-of-the-art climate and earth system models predict a wide range of fresh water distribution in the northern hemisphere for the later part of the current century. The rate of freshening in southern high latitudes is still unclear due to lack of knowledge and uncertainty in modelling strategies of ice-ocean interaction.

This workshop reaches out to observational, modelling, remote sensing and assimilation communities to gain a holistic overview of the role of fresh water and the future evolution at high latitudes. We welcome both regional and global ocean communities. One focus will be the linkage of the regional hydrological cycle, from source to export, and the dynamical impact on global ocean circulation and climate. The discussion aims at making recommendations for critical model improvements to better represent the distribution of salinity and ice-ocean processes while assessing available, necessary and desirable observations. The exact topics for the breakout discussion groups will be decided after feedback from registered participants.

This workshop will focus on the following topics:

• Hydrological cycle
• ​Ocean fresh water linkages to global circulation
• Regional sources and sinks
• Effects of solid and liquid fresh water on regional environment (e.g. ocean circulation and stratification)

More info: https://www.clivar.org/events/norp-sorp-workshop-polar-fresh-water-sources-pathways-and-impacts-fresh-water-northern-and

The Role of Freshwater in Polar Ocean Climate Change and Global Linkages Workshop is co-funded through the IASC Working Group funds with contributions from the IASC Marine WG.