Ben Holt Jet Propulsion Laboratory ben@pacific.jpl.nasa.gov 818-354-5473 October 08, 1999 Product name: SAR floe size. Floe size distributions derived from spaceborne SAR imagery. Floe sizes derived using algorithm referenced in 1) Soh, L.-K., B. Holt, and C. Tsatsoulis, Identifying ice floes and computing ice floe distributions in SAR images, in Analysis of SAR Data of the Polar Regions, C. Tsatsoulis and R. Kwok (eds.), Springer-Verlag, New York, 9-34, 1998. Reprint available upon request. A) Input Data: SAR imagery processed by Alaska SAR Facility from European Space Agency's ERS-1 and ERS-2, Canadian Space Agency Radarsat-1, Japanese JERS-1. Characteristics Pixel size = 100 by 100 m Swath width = 100 km for E1/E2, 450 km for R1, 80 km for J1 For further details of SAR characteristics and format, go to http://www.asf.alaska.edu B) Output data: 1. floe size distribution file name: floeXXXXXXX.dat Contains count and percentage of total pixels per output category per frame EX. floeE2081701.dat E2=SAR sensor where E1=ERS-1, E2=ERS-2, R1 =Radarsat 1,J1=JERS-1 0817= MMDD, 1998 01 = frame number file format: Odd lines = count or number of pixels per category,XXXXXX Even lines = percent, number of pixels per category / Total number of pixels per frame, XX.XXXX Total number of pixels per frame = 999424 Pixel size = 100m x 100m Floe class size defined in Table 1 Line 1,2 Water: Note-these are not accurate, do not use Line 3,4 Substrate: water/ice mixture Line 5,6 Floe discarded= floes not sufficiently compact Line 7,8 Floe size class 1 Line 9,10 Floe size class 2 Line 11,12 Floe size class 3 Line 13,14 Floe size class 4 Line 15,16 Floe size class 5 Line 17,18 Floe size class 6 Line 19,20 Floe size class 7 Line 21,22 Floe size class 8 Line 23,24 Floe size class 9 Line 25,26 Floe size class 10 Line 27,28 Floe size class 11 Line 29,30 Floe size class 12 Line 31,32 Floe size class 13 Line 33,3 Floe size class 14 Line 35,36 Floe size class 15 Line 37,38 Floe size class 16 Table 1. Floe Size Classes Class Pixel Mean Size Mean Size Mean Min-Max No. Range Pixels Area (km^2) Diameter*(km) Area(km^2) 1 1 1 0.01 0.123 0.01-0.01 2 2 2 0.015 0.151 0.02-0.02 3 3-4 3.5 0.035 0.230 0.03-0.04 4 5-8 6.5 0.065 0.314 0.05-0.08 5 9-16 12.5 0.125 0.435 0.09-0.16 6 17-32 24.5 0.245 0.609 0.17-0.32 7 33-64 48.5 0.485 0.857 0.33-0.64 8 65-128 96.5 0.965 1.209 0.65-1.28 9 129-256 192.5 1.925 1.708 1.29-2.56 10 257-512 384.5 3.845 2.414 2.57-5.12 11 513-1024 768.5 7.685 3.412 5.13-10.24 12 1025-2048 1536.5 15.365 4.825 10.25-20.48 13 2049-4096 3072.5 30.725 6.823 20.49-40.96 14 4097-8192 6144.0 61.440 9.648 40.97-81.92 15 8193-16,384 12,288.5 122.885 13.645 81.93-163.84 16 >16,385-10^6 24,572.5 245.725 19.295 163.85-10^5 *Derived from Rothrock and Thorndike (J. Geophys. Res. 89(C4), 6477-6486, 1984) where Area = a L^2 where a=0.66 and L=diameter. Examples of data usage: number of floes per size class in km^2 = count per class divided by mean size pixels per class x 0.01 km^2 2) Location and time of SAR input images used to derive floe size distributions File name: locationSARfloe.dat Column Headings: floe Floe size filename = floeXXXXXXX.dat ctim Center Time = MMDDHHMMSS, 1998 clat Center Lat clon Center Lon lat1 Corner1Lat lon1 Corner1Lon lat2 Corner2Lat lon2 Corner2Lon lat3 Corner3Lat lon3 Corner3Lon lat4 Corner4Lat lon4 Corner4Lon ASF Alaska SAR Facility SAR Granule, original SAR image product file name File name: locationSARfloe.dat : floeE2081701 0817225726 78.60 -156.63 77.98 -155.99 78.74 -153.46 78.43 -159.72 78.74 -153.46 E2 floeE2082001 0820230237 80.23 -151.92 79.59 -151.53 80.30 -148.17 80.16 -155.60 80.86 -152.38 E2 floeE2082002 0820230250 79.59 -154.60 78.95 -154.09 79.69 -151.10 79.45 -158.03 80.22 -155.19 E2 floeE2082003 0820230303 78.93 -156.99 78.30 -156.39 79.06 -153.71 78.77 -160.19 79.56 -157.68 E2 floeE2082301 0823230823 80.23 -153.36 79.59 -152.97 80.30 -149.61 80.12 -157.05 80.86 -153.82 E2 floeE2082601 0826231408 80.23 -541.81 79.59 -154.42 80.30 -151.06 80.12 -158.50 80.86 -155.27 E2 17519245