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The Nordic Centre of Excellence CRAICC (Cryosphere–Atmosphere Interactions in a Changing Arctic Climate), funded by NordForsk in the years 2011–2016, is the largest joint Nordic research and innovation initiative to date, aiming to strengthen research and innovation regarding climate change issues in the Nordic region. CRAICC gathered more than 100 scientists from all Nordic countries in a virtual centre with the objectives of identifying and quantifying the major processes controlling Arctic warming and related feedback mechanisms, outlining strategies to mitigate Arctic warming, and developing Nordic Earth system modelling with a focus on short-lived climate forcers (SLCFs), including natural and anthropogenic aerosols. The outcome of CRAICC is reflected in more than 150 peer-reviewed scientific publications, most of which are in the CRAICC special issue of the journal Atmospheric Chemistry and Physics. This paper presents an overview of the main scientific topics investigated in the centre and provides the reader with a state-of-the-art comprehensive summary of what has been achieved in CRAICC with links to the particular publications for further detail. Faced with a vast amount of scientific discovery, we do not claim to completely summarize the results from CRAICC within this paper, but rather concentrate here on the main results which are related to feedback loops in climate change–cryosphere interactions that affect Arctic amplification.

We review progress in Baltic Sea physical oceanography (including sea ice and atmosphere-land interactions) and Baltic Sea modelling, focusing on research related to BALTEX Phase II and other relevant work during the 2003-2014 period. The major advances achieved in this period are: Meteorological databases are now available to the research community, partly as station data, with a growing number of freely available gridded datasets on decadal and centennial time scales. The free availability of meteorological datasets supports the development of more accurate forcing functions for Baltic Sea models. In the last decade, oceanographic data have become much more accessible and new important measurement platforms, such as FerryBoxes and satellites, have provided better temporally and spatially resolved observations. Our understanding of how large-scale atmospheric circulation affects the Baltic Sea climate, particularly in winter, has improved. Internal variability is strong illustrating the dominant stochastic behaviour of the atmosphere. The heat and water cycles of the Baltic Sea are better understood. The importance of surface waves in air-sea interaction is better understood, and Stokes drift and Langmuir circulation have been identified as likely playing an important role in surface water mixing in sea water. We better understand sea ice dynamics and thermodynamics in the coastal zone where sea ice interaction between land and sea is crucial. The Baltic Sea's various straits and sills are of increasing interest in seeking to understand water exchange and mixing. There has been increased research into the Baltic Sea coastal zone, particularly into upwelling, in the past decade. Modelling of the Baltic Sea-North Sea system, including the development of coupled land-sea-atmosphere models, has improved. Despite marked progress in Baltic Sea research over the last decade, several gaps remain in our knowledge and understanding. The current understanding of salinity chan

The ice-ocean response to variable winds is analysed based upon two types of models. An analytical ice-ocean model with linear stress laws and forced by periodic winds is first derived. Secondly a numerical, vertically resolved ice-ocean model is introduced. In the numerical model, the ice-water stress law is calculated from a turbulence model and the wind stress is calculated on the basis of a square law formation. By comparing the ice-ocean stress law formulations, it is illustrated that the numerical model predicts an ice-ocean stress law that has a power slightly less than 2 compared to 1 for the analytical model. The numerical prediction is in good accordance with field observations and the slight deviation from 2 is due to wall effects close to the ice-water interface. It is then demonstrated that the ice-ocean response to variable winds could be well simulated by both models, but the analytical model did not capture the wind dependency properly (because of the linear approach). The ice and current factors are amplified at wind frequencies close to inertial (omega = -f) and damped at high positive and negative frequencies. The maximum ice and current factors at a wind frequency equal to the inertial oscillation are shown to be dependent only on the friction coefficients. With the constants applied in the present study, the maximum ice drift and current speed are equal to 7.8% and 5.5% of the wind speed, respectively. These steady state values are however quite unrealistic as they would require a uniformly changing wind direction for many inertial periods.

Contents: A Note on Estimating Melt Rate in the MIZ; Kinematics of Marginal Ice: MIZEX 83; On Estimating Ice Stress from MIZEX 83 Ice Deformation and Current Measurements; Crystal Structure of Fram Strait Sea Ice; MIZEX 84 Ice Surface Measurements from the FS Polarstern; 1984-85 Current Observations in the East Greenland Current: A Preliminary Description; An Ice/Air Feedback Mechanism for the Migration of the Marginal Ice Zone; The Planetary Boundary Layer in the Marginal Ice Zone; and An Air Ice Ocean Coupled Model for the Formation of Leads or Polynyas., Original contains color plates: All DTIC/NTIS reproductions will be in black and white. See also report dated Apr 86, AD-A169 070.

Contents: Drift Velocity During the Drift-Station Phase of MIZEX 83; MIZEX 83--BIO Buoy Data Summary; MIZEX 83 Mesoscale Sea Ice Dynamics--Initial Analysis; On the Rheology of a Broken Ice Field Due to Floe Collision; Heat and Mass Balance Observations During the MIZEX 83 Drift Program; Ocean Currents and Temperatures in the Center of Fram Strait During MIZEX 83; and Arctic Whitecapping--Preliminary results., See also Rept. nos. CRREL-SR-81-19, AD-A107 046 and CRREL-SR-83-12, AD-A134 872.

The report describes an extension of the use of the Del Norte microwave transponder system to obtain improved accuracy of measurement of ice movements. Among the improvements was the use of two transponders on a single flow, making it possible to obtain rotational as well as translational movements. The ice flow were normal for marginal ice zone summer conditions. Flow sizes ranged from 30m to 200m, but a few large flows of 1-2km were present, ice thickness was 1-4m. Ice concentration ranged from 0.6 to 0.9 until 8 July 84, after which it declined to 0.3. Flows may rotate as much as 90 deg in a 24hr period.