21 February - 16 March 2006

The animations¹ are produced by combining daily composite GIF images of backscattered radar signal (vertical polarization) measured from space with data from scatterometers.  Originally developed to measure surface winds over the ocean surface, the backscattered radar signal is also related to surface ice roughness, wetness and other conditions.  Unlike visible and infrared imagery from satellite, the scatterometer signal is essentially uneffected by clouds in the Arctic. Individual ASCAT images archived at NESDIS may be viewed here (courtesy of Dr. Paul Chang, NOAA/NESDIS). The QuikSCAT mission ended in 2009.

In the recent (winter 2006) animations, there appear to be episodes of large areas of ice breaking away from fast ice near the Siberian coast (likely wind forcing) and new ice forming in the linearly extended leads.  This behavior has been observed and verified to occur in the Antarctic (David Long, personal communication).  In most cases, the apparent movement of brightness (roughness) features is probably indicative of actual ice movement (if the roughness properties change slowly between images).   An exception to this can be where melting or freezing occurs and there are widespread changes in brightness as compared to that explained by ice movement.   

¹The Animations Applet (AniS) used for interactive animations were developed by Tom Whittaker of the Space Science and Engineering Center  SSEC, University of Wisconsin-Madison.  The animations can take a while to load, depending on network speed, computer systems, etc. Also, there can be a problem viewing these on certain machines (Macs).

²Data is unavailable in the area centered on the North Pole which also appears in black.

References:

Long, D.G., and M.R. Drinkwater, 1999. "Cryosphere Applications of NSCAT Data, IEEE Transactions Geoscience and Remote Sensing", 37 (3), 1671-1684. Remund, Q.P., and D.G. Long, 1999 . "Sea Ice Extent Mapping Using Ku-Band Scatterometer Data", Journal of Geophysical Research, 104 (C5), 11515-11527.

J. Haarpainter, R.T. Tonboe, D.G. Long and M. L. VanWoert, "Automatic Detection and Validity of the Sea Ice Edge: An Application of Enhanced Resolution QuikScat/SeaWinds Data," IEEE Transactions on Geoscience and Remote Sensing, Vol. 42, No. 7, pp. 1433-1443, 2004.

Links:

Science grade data is available from: http://www.scp.byu.edu

Operational near real-time images are available from: http://science.natice.noaa.gov/quickstaticemask.htm and http://manati.orbit.nesdis.noaa.gov/cgi-bin/qscat_ice.pl

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 SOME ESTIMATES OF ICE COVER from PASSIVE MICROWAVE INSTRUMENTS

The following maps of sea ice concentration were downloaded from the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.  Proper credit should be given to the authors listed below when citing these data.  Data is derived from passive microwave instruments (SSM/I) on the polar orbiting DMSP satellites.  These are based on algorithms which relate the measured microwave radiation to coverage of surface ice.  Owing to the limited resolution of the microwave radiometers (as compared to visible or infrared), the resolution of these analyses is on the order of 25-50km.  The advantage of the microwave is that the estimates are available in most cloudy conditions. This is not possible with visible and infrared observations. Note also that no observations are available from these satellites in vicinity of the pole.