The Environment of the Arctic: Climate, Ocean and Sea Ice

Aims

1. To improve understanding of contemporary Arctic ocean and sea ice variability & trends
2. To reduce uncertainty of future (seasonal–decadal) predictions of Arctic climate

Objectives

1. Identification and quantification of critical present-day Arctic ocean and sea ice processes, specifically issues related to momentum transfer, dense water formation, mixing, and heat and freshwater fluxes
2. Diagnosis of present and prognosis of future Arctic ocean and sea ice circulation, fluxes, and dynamics, using a hierarchy of inverse, idealized, GCM and coupled climate models, tested with new observations
3. Evaluation of future Arctic regional climate and wider consequences of change, using a coupled IPCC-class climate model, taking into account the improved knowledge and understanding of the consequences of sea ice reduction on Arctic ocean circulation and fluxes.

Methodology & Approach

To achieve the project objectives, we propose a linked suite of studies employing new and existing measurements, process models and coupled climate models. To evaluate, improve and validate the representations of key processes in models related to momentum, energy and freshwater exchanges (Objective 1) requires a combination of new observations with the development of new inverse models and parameterisations. Our programme will employ new (and historical) satellite and in-situ observations to provide the quantitative constraints necessary to produce new and accurate parameterisations of surface momentum flux and turbulence.

To estimate seasonally-resolved boundary fluxes requires the integration of in-situ and remote-sensed measurements using an inverse model. The Arctic ocean and sea ice system is complex, and the result of interaction between mechanical and buoyancy fluxes, local and remote forcing, and topography.

To isolate the roles of individual processes in controlling Arctic ocean heat and freshwater fluxes, both in present and future (ice-free) conditions (Objective 2), we will conduct a series of idealized model experiments, incorporating new parameterisations.

To improve predictions of future climate using a coupled climate first requires evaluation of the climate model under present-day conditions. We will test an IPCC-class climate model (Objective 2) against both the new observations and the results of the idealized model experiments to determine the model’s skill in reproducing present-day Arctic ocean-ice system. We will then conduct a series of experiments to determine the future impact of the sea ice retreat and increases in momentum and freshwater fluxes on Arctic and regional climate (Objective 3).