Nares Strait Atmospheric Modeling R. M. Samelson, P. Barbour

Goals and Objectives  Estimate atmospheric forcing in Nares Strait, where measurements are difficult to obtain  Improve physical understanding

Approach  Daily mesoscale atmospheric model simulations (Polar MM5)  Forecast mode, nested in operational global model (NCEP AVN)  Archive and construct continuous hourly time series  Analyze and provide to collaborators

The Largest (and Coldest) Wind “Tunnel” on Earth? Nares Strait: 300 km x 35 km x m January 2005: monthly mean 10-m wind and SLP Strong surface flow down pressure gradient from Lincoln Sea to Baffin Bay 9-10 months of the year January 2005: northward (red) and eastward (blue) 10-m wind

3-4 November 2006 From: ‘41-mb along the Strait! This is one of the largest that I have seen…here is a great thermal band image.… Note the new polynyas in north-eastern Hall and Kane Basins and the intense convection in the cold Arctic air mass as it moves out over open water in Baffin Bay. There is also indication of an ice bridge across the Lincoln Sea, with a new polynya forming there.’

3-4 November November 2006: northward (red) and eastward (blue) 10-m wind 22 UTC 3 Nov UTC 4 Nov m/s 500 m

Samelson, R. M., T. Agnew, H. Melling, and A. Münchow, Evidence for atmospheric control of sea-ice motion through Nares Strait. Geophysical Research Letters, 33, L02506, doi: /2005GL Atmospheric Control of Sea-Ice Motion ABSTRACT: Satellite observations of ice motion are combined with model estimates of low-level winds and surface wind stress to provide evidence for atmospheric control of sea-ice motion through Nares Strait, between Ellesmere Island and Greenland, during two periods in The results suggest that ice flux through the strait, and its shutdown through the formation of a landfast ice mass in the strait, can be controlled by wind stress and atmospheric cooling. Analysis of the model results during these two periods also suggest that the intense, low-level, along-strait winds are strongly ageostrophic, and may be usefully estimated from pressure differences along the Strait.

 Complete analysis of two-year (three-year?) climatology  Reconstruct 50-year wind time series from Alert-Thule SLP  Future work: Compare model winds to in-situ observations from AWS recently deployed near Davis Strait by G. W. K. Moore (U Toronto) In Progress

Aug 03 - Jul 05: Mean and EOFs #1 and #2 Wind speed

Aug 03 - Jul 05: Mean and EOFs #1 and #2 Wind stress

Aug 03 - Jul 05: Mean and EOFs #1 and #2 SLP

Aug 03 - Jul 05: EOF amplitudes SLP #1 Wind Stress #1 SLP #2 Wind #1

Aug 03 - Jul 05: EOF amplitudes SLP #2 and Wind stress #1 and #2

50-year Reconstructed Nares Strait Wind Time Series Approach: Construct 50-year time-series of Alert-Thule SLP difference; convert to surface wind and stress using linear regression derived from model results

 Evidence found for atmospheric control of Nares Strait ice flux (GRL, 2006)  Analysis of model climatology near completion  50-year wind reconstruction in progress, using model-based SLP-wind relation  Mesoscale model simulations to continue through 2007 Summary