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RECENT CHANGES IN JULY- OCTOBER SEA ICE IN THE BEAUFORT SEA: 1997-2012 Mike Brady University of Waterloo.

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Presentation on theme: "RECENT CHANGES IN JULY- OCTOBER SEA ICE IN THE BEAUFORT SEA: 1997-2012 Mike Brady University of Waterloo."— Presentation transcript:

1 RECENT CHANGES IN JULY- OCTOBER SEA ICE IN THE BEAUFORT SEA: 1997-2012 Mike Brady University of Waterloo

2 INTRODUCTION The Beaufort Sea; a key area of interest Record minimum sea ice extents in recent years Decreases in sea ice thickness and concentration increase the ice cover’s vulnerability to external forcing Freshwater retention increasing due to a strengthening Beaufort Gyre (Giles et al., 2012)

3 Beaufort Gyre Transport mechanism unique to Beaufort Sea Predominantly anti- cyclonic INTRODUCTION Figure 1 from Lukovich & Barber (2012)

4 INTRODUCTION Objectives Produce a time series of sea ice flux between the Beaufort Sea and the Canada Basin Generate a monthly climatology of sea ice motion for the Beaufort Sea

5 Beaufort Sea Canadian Arctic Archipelago to Barrow, Alaska Extents of CIS WA regional ice charts STUDY AREA

6 DATA AND METHODS RADARSAT-1 & RADARSAT-2 ScanSAR Wide (500km) imagery 100m pixel size resampled to 200m ~29,000 usable swaths (11,441 for July-Oct)

7 CIS-ASITS Identify and track suitable ice parcels in sequential SAR image pairs Estimate rotational and translational components of ice motion through phase correlation approach (Komarov & Barber, 2012) Previously applied in related works (Howell et al., 2013; Wohelleben et al., 2013) DATA AND METHODS

8 Flux Estimation “North Beaufort” Gate 756 km Inflow and outflow estimated from CIS- ASITS outputs coupled with CIS ice concentrations DATA AND METHODS

9 LIMITATIONS OF METHODS CIS-ASITS has difficulty resolving suitable ice floes in summer months due to surface melt Gate length introduces issues with multi-crossings and possible exaggerated/misrepresented motion estimates Decreased availability of imagery in RADARSAT-2 portion of study (mid-2008 to 2012) may misrepresent motion and affect flux estimates

10 EXAMPLES OF MULTI-CROSSINGS pair_19980929163642_19980930160719 pair_20031029160133_20031030015905





15 NEXT STEPS Validate flux estimates with ground data (IABP buoy drift tracks) Conduct more robust comparisons with climate variables (NCEP/NCAR Sea Level Pressure/Vector Wind/Air Temperature) Finish generating monthly composites of ice motion vectors from CIS-ASITS outputs

16 THANK YOU References Giles, K. A., Laxon, S. W., Ridout, A. L., Wingham, D. J., & Bacon, S. (2012). Western Arctic Ocean freshwater storage increased by wind-driven spin-up of the Beaufort Gyre. Nature Geoscience, 5(3), 194–197. doi:10.1038/ngeo1379 Howell, S. E. L., Wohlleben, T., Dabboor, M., Derksen, C., Komarov, A., & Pizzolato, L. (2013). Recent changes in the exchange of sea ice between the Arctic Ocean and the Canadian Arctic Archipelago. Journal of Geophysical Research: Oceans, 118(7), 3595–3607. doi:10.1002/jgrc.20265 Komarov, A., & Barber, D. (2012). Detection of sea ice motion from co- and cross- polarization RADARSAT-2 images. In 2012 IEEE International Geoscience and Remote Sensing Symposium (Vol. 7, pp. 3277–3280). IEEE. doi:10.1109/IGARSS.2012.6350604 Lukovich, J. V., & Barber, D. G. (2006). Atmospheric controls on sea ice motion in the southern Beaufort Sea. Journal of Geophysical Research, 111(D18), 1–12. doi:10.1029/2005JD006408 Wohlleben, T., Howell, S. E. L., Agnew, T., & Komarov, A. (2013). Sea-Ice Motion and Flux within the Prince Gustaf Adolf Sea, Queen Elizabeth Islands, Canada during 2010. Atmosphere-Ocean, 51(1), 1–17. doi:10.1080/07055900.2012.750232

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