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ESTIMATING SEA ICE TRANSPORT INTO THE NORTH ATLANTIC USING THE AMSR-E SATELLITE SENSOR Tom A. Agnew, Climate Research Branch, Meteorological Service of.

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Presentation on theme: "ESTIMATING SEA ICE TRANSPORT INTO THE NORTH ATLANTIC USING THE AMSR-E SATELLITE SENSOR Tom A. Agnew, Climate Research Branch, Meteorological Service of."— Presentation transcript:

1 ESTIMATING SEA ICE TRANSPORT INTO THE NORTH ATLANTIC USING THE AMSR-E SATELLITE SENSOR Tom A. Agnew, Climate Research Branch, Meteorological Service of Canada and Jared Vandeweghe University of Toronto Toronto, Canada

2 OUTLINEOUTLINE How Arctic freshwater cycles through the Global Climate System Canadian Archipelago Through-flow Study (CATS) and how we can use satellites to estimate sea ice transport. Results using the Advanced Microwave Scanning Radiometer (AMSR-E) to estimate the rate of sea-ice transport into the North Atlantic.

3 85 th AMS, San Diego,11/01/05 Temperature Stratified Ocean Salt Stratified Ocean Freshwater Cycle Courtesy of Eddie Carmack, IOS

4 85 th AMS, San Diego,11/01/05 Sea ice export into the North Atlantic

5 85 th AMS, San Diego,11/01/05 NSF/SEARCH - funded study for 5–year 2002 to 2007 2003 Ocean expeditions to set up moorings (currents, salinity, ice draft, pressure, tracers) Ocean Surveys (tracers, hydrography, velocity) Remote Sensing (AMSR-E*, MODIS, AVHRR) Modeling (sub-mesoscale winds) Activities Kelly Falkner, Roger Samelson, Marta Torres, Oregon State University (OSU) Andreas Münchow, Kuo Wong, University of Delaware (UDel) Humfrey Melling, Fiona McLaughlin, Robie Macdonald, Eddy Carmack, Institute of Ocean Sciences (IOS), Canada Tom Agnew, Atmosphere & Environment, Canada Peter Jones, John N. Smith, Bedford Institute of Oceanography (BIO), Canada Andrew Weaver, University of Victoria (Uvic), Canada Investigators Canadian Archipelago Through-flow Study (CATS) Objective: To estimate the rate of transport of freshwater through the Canadian Archipelago into Baffin Bay/Labrador Sea

6 Sea Ice Motion from AMSR-E Image Pairs January 9-13, 2003

7 85 th AMS, San Diego,11/01/05 AMSR-E Sea Ice motion and Buoy Comparison SeparationObservations Mean of the Differences (km/day) SD of Difference (km/day) Mean Displacement of the Buoys (km/day) 1-day 195-0.33*( 6.5%) 2.495.06 * Negative mean underestimation compared to drifting buoys

8 85 th AMS, San Diego,11/01/05 Daily Sea Ice Area Transport across flux gates Ice Area Flux = ∑ c i u i Δx gate a gate c

9 85 th AMS, San Diego,11/01/05 Estimating Daily Sea Ice Area Flux Error 2. Error in daily flux: σ f = σ e L/(Ns) ½ = 320 km 2 /day where Ns = independent estimates = 10 and L = 400 km 3. Monthly error: σ T = σ f (Nd) ½ = 1752 km 2 /month 4. Winter error estimate: ~ 5000 km 2 /winter 5. For previous sensor: 17,000 – 25,000 km 2 /winter 1. Error in estimating u i is 2.49 km/day Error in estimating c i is 10% c i u i is σ e = 2.53 km/day

10 85 th AMS, San Diego,11/01/05 Sea Ice Area Transport Winter 02/03 and 03/04 651,000 km 2 594,000 km 2

11 85 th AMS, San Diego,11/01/05 Estimated Volume of Freshwater Flux in Winter Area Flux (km 2 ) Thickness (m) Ice Volume ( km 3 ) Meltwater ( km 3 ) Freshwater (km 3 ) Baffin Bay (gate c) 651,0001.5975870825 Fram Strait (gate a) 594,0004240021001900 Reference Salinity of sea ice Ice to meltwater (fm) Water to FW (fs) Ice volume to FW (fs*fm) Ice volume to FW yield (fs*fm/A) 34.8 ppt2.7 ppt0.890.920.820.118

12 85 th AMS, San Diego,11/01/05 Average winter sea ice area transport through Fram Strait for 02/03 and 03/04 winter is 594,000 km 2 (the average of 754,000 km 2 found by Kwok et al. 2004). The error in estimating the winter ice flux is ~ 5000 km 2 for the AMSR-E sensor. This error estimate is a considerable improvement over estimates using earlier passive microwave sensors which range from 17,000 and 25,000 km 2 The sea ice area flux across the widest part of Baffin Bay is 651,000 km 2 which is 20% higher than the area flux across Fram Strait. However, when you include ice thickness Fram Strait ice volume export is 2400 km 3 compared to 975 km 3 for Baffin Bay. Using the improved accuracy of AMSR-E we hope in future to estimate sea ice area flux in the main channels of the Canadian Arctic Islands and compare results with ocean moorings set up in these channels under CATS. Summary

13 85 th AMS, San Diego,11/01/05 THANK YOU Acknowledge: Canadian PERD US NSF/SEARCH NSIDCIABP

14 First ImageSecond Image ++ Uses the cross correlation coefficient as a measure of similarity between patches or sub-regions in the two images. Select a sub-region or patch in the first image. Then search in the second image using the same size patch until you maximizes the cross- correlation between patches in the two images. Ice motion is the spatial offset between the two patches patch size is 6 pixels by 6 pixels (37.5 km x 37.5 km) Maximum Cross Correlation Method


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