|Arctic Sea Ice Animation||r_swick||11/9/07 10:23 AM|
The National Snow and Ice Data Center (NSIDC) has released a new animation for Google Earth showing two months of daily sea ice conentrations in the Arctic, leading up to the record shattering sea ice minimum on September 16, 2007. Images are derived from the The Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent (NISE) product which has been produced at NSIDC on a daily basis for the past decade.
The monthly average sea ice extents for July, August, and September are also shown to give an indication of how dramatic the retreat was this season.
The 600 KB kmz file is available from our Technical Experiments page. It is still considered "beta" while it makes it's way through our ponderous review process. Once the review process completes it will move to our Virtual Globes Homepage but I thought people might appreciate an advance look.
Ross S. Swick National Snow and Ice Data Center University of Colorado, Boulder, CO
|Re: Arctic Sea Ice Animation||r_swick||7/11/08 11:20 AM|
This year we've gotten a head start on the Arctic sea ice melt season. Instead of releasing a two month animation after the fact we've created an animation of Arctic sea ice concentration for the last 60 days which will be updated daily. The idea is folks can watch the arctic melt as it's happening this summer.
The kml is still beta in that some of the screen overlays need work and the popup text could stand some editing. But the animation is functioning fine and we can already see some areas losing ice cover sooner than normal. As the cosmetics get fixed we'll include those in the daily updates which the top level kml calls via a network link.
The beta version is currently the top entry on our "Technical Experiments" page at:
|Re: Arctic Sea Ice Animation||Kempster||7/11/08 11:24 AM|
|Re: Arctic Sea Ice Animation||r_swick||8/4/08 9:28 AM|
We've finished our internal review of the near real time Arctic sea ice animation and released it on our virtual globes home page. We now include both sea ice concentration and sea ice extent animations, updated daily. Additionally the animation now comes in 30, 60, and 90 day versions, to accommodate users with different needs/capabilities.
NSIDC Data on Virtual Globes
I've also reprocessed the data for all of 2008 to create a consistent image set for users that want to create their own animations or use the images as a base layer. The 2008 sea ice concentrations use 100 shades of blue (1-100%) while the 2007 imagery only used 5 shades (concentrations in 20% chunks) The 2008's images look a lot better and we hope to reprocess the entire 10-year time series in the near future.
Note that the images are all transparent pngs, northern hemisphere only. Also note that the images are in a Cylindrical Equidistant projection using a reference latitude of 70. This makes them look a bit stretched as 2-D images since most people are used to the Equatorial (reference lat = 0) Cylindrical Equidistant projection. We use a reference latitude of 70 for polar data because using a reference latitude close to where the data is makes the images look a lot better when draped over the globe.
NSIDC sea ice images
Images are sorted by year and the average monthly extent files are in the "monthlys" directory. Keep in mind these are images - not data - so standard caveats apply. If you plan to make extensive use of these images please think about hosting them on your own server.
|Re: Arctic Sea Ice Animation||r_swick||9/15/08 10:21 AM|
Just in time for the Arctic sea ice minimum NSIDC has released a second set of animations for Google Earth. As before we have created 30- 60- and 90-day animations of sea ice concentration and extent that we update daily so users can follow events as they happen.
While the first set of animations are based on data from the Special Sensor Microwave/Imager (SSM/I) on the Defense Meteorological Satellite Program (DMSP) F13 satellite, the new set is based on data from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) sensor on NASA's Aqua satellite. The significant differences between the two datasets are: AMSR-E has twice the resolution as SSM/I (12.5km vs 25km) and AMSR-E has a wider swath so there is better coverage near the pole.
On average the minimum sea ice extent in the Arctic occurs on Sept. 12, though last year it did not take place until the 16th. As the calculation of the daily extent is based on a 5-day running mean we won't know what day the minimum actually occurs until two days later.
The 2007 minimum sea ice extent shattered all previous records and this years extent is close to breaking that record. Even if 2008 stands as only the second lowest Arctic sea ice extent it will have shattered all previous records save one.
The new animations, as well as the "old" ones, are available from our Virtual Globes Homepage.