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The multi-disciplinary, long-term, satellite-based Earth Observations (EO) form a tremendous synergy of data and information products that should to be more systematically and consistently explored, from the short synoptic time scales to the longer decadal time scales. This lays the rationale for the ESA funded Arktalas Hoavva study project. A stepwise multi-modal analyses framework approach benefitting from native resolution satellite observations together with complementary in-situ data, model fields, analyses and visualization system and data assimilation tools will be applied.  Following this approach, the overall goal is to remove knowledge gaps and advance the insight and quantitative understanding of sea ice, ocean and atmosphere interactive processes and their mutual feedback across a broad range of temporal and spatial scales. In turn, four major existing interlinked Arctic Scientific research Challenges (ASC) will be investigated, including:

ASC-1: Characterize Arctic Amplification and its impact (ASC-1)

Central elements (not exclusive) are: – reduction in sea ice extent and concentration; – changes in albedo; – changes in the radiation balance; – increased air temperature; – delayed onset of sea ice freezing; – early onset of sea ice melting; – increasing area of melt ponds and polynias; – increased lead fraction; – changes in snow cover and SWE; – changes in ocean-atmosphere momentum, heat exchange and gas exchanges; – reduction in fast ice area; – thinning of sea ice thickness; – changes in optical conditions in the upper ocean with influence on the biology and marine ecosystem; – more favourable conditions for sea ice drift; – more meltwater; – larger fetch; – enhanced wave-sea ice interaction; – more wave induced sea ice break-up; – modifications to atmospheric boundary layer and changes in weather pattern; – influence on Arctic vortex and hence teleconnection to mid-latitudes.

ASC-2: Characterize the impact of more persistent and larger area open water on sea ice dynamics 

Building on ASC-1,  this is associated with: – increasing momentum transfer to the upper ocean leading to more turbulent mixing and possibly entrainment of warm Atlantic Water below the halocline; – increasing Ekman effects; – changes in sea ice growth, salt rejection and halocline formation; – larger fetch and lower frequency waves penetrating further into the ice covered regions leading to more floe-break-up; – increasing lead fraction and more sea ice melting; – reduction in sea ice flow size, age,  thicknesses and extent and subsequent change in sea ice mechanical behaviour; – possibly more abundance of internal waves and mesoscale and sub-mesoscale eddies generated in the open ocean with subsequent abilities to propagate into the ice covered regions leading to changes in sea ice deformation and dynamics.

ASC-3: Understand, characterize and predict the impact of extreme event storms in sea-ice formation

Growing areas of open water within the Arctic Ocean and the neighbouring seas will be more effectively exposed to extreme events. Cold air outbreak and polar lows, for instance, are known to have strong impact in the Marginal Ice Zone (MIZ), including; – enhanced momentum transfer and vertical mixing; – enhanced sea ice formation; – enhanced formation of unstable stratification in the atmospheric boundary layer; – more low cloud formations changing the radiation balance; – set up abnormal wave field to strengthen wave induced sea ice break-up; – abnormal impact on the pycnocline and subsequent entrainment of heat into the upper mixed. A central question is eventually whether the Arctic amplification will trigger increasing frequency of occurrences and strength of extremes.

ASC-4: Understand, characterize and predict the Arctic ocean spin-up

The ongoing Arctic amplification and subsequent changes, mutual interactions and feedback mechanisms are also expected to influence the basin scale atmospheric and ocean circulation within the Arctic Ocean.  In particular, this will address: – freshwater distribution and transport; – importance of Ekman pumping; – changes in water mass properties; – changes in upper ocean stratification and mixing; – changes in sub-surface heat exchange; – possibly more abundance of mesoscale and sub-mesoscale eddies and internal waves generated in the open ocean with subsequent abilities to propagate into the sea ice covered regions.

The Arktalas Hoavva project kicked-off 9 July 2019 and will be executed over a 24 months period through the following seven interconnected tasks with mutual input-output feeds as schematically illustrated in the figure below. One of the major outcomes of the project is six dedicated research papers emerging from Task 3 that are specifically addressing the Arctic Scientific Challenges. These papers will be published in peer review journals. Moreover, the project will develop a visualization portal in polar-stereographic configuration that will be connected to the Arktalas data archive and allow users to access and make use of the Arktalas satellite-based, in-situ and model-based dataset during the project.


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