In the sea dating web
Is wintertime Antarctic sea ice increasing or decreasing?
Our originally published value was 4.13 million square kilometers.
Example: Let’s say you have three 25 kilometer (km) x 25 km (16 miles x 16 miles) grid cells covered by 16% ice, 2% ice, and 90% ice.
Two of the three cells would be considered “ice covered,” or 100% ice.
This lack of data is indicated by a gray circle, or “pole hole,” in each image.
Created: June 2008 Related question: How will we know if ice at the North Pole melts?
Why are the daily minimum values that you are currently quoting for past years slightly different than what you originally stated? The new calculations show, for example, that the record minimum occurred on September 18, 2007, which was two days later than we originally reported (September 16).
Why is the monthly average extent not equal to the average of the daily extent values? Why do you use the 1981–2010 average for comparisons? In addition, NSIDC updates extent values, calculated initially with near-real-time data, when final processed data becomes available.
Fortunately, some satellite sensors are able to obtain data directly over the North Pole; Data from these satellites could be used to fill in data that are missing from other satellite records.
For example, the NASA Advanced Microwave Scanning Radiometer—Earth Observing System (AMSR-E) could fill in some missing data because it has a smaller pole hole than other satellites.
Extent would be a measure of the edges of the slice of cheese and all of the space inside it.
Area would be the measure of where there is cheese only, not including the holes.
So, while reliable for measuring area most of the year, the microwave sensor is prone to underestimating the actual ice concentration and area when the surface is melting.