Yesterday, as covered by WUWT, NSIDC announced that Arctic sea ice melt had turned the corner on September 10th with a value of 4.14 million square kilometers:
XMETMAN writes of his discovery of a discrepancy between what NSIDC announced yesterday, and what their data actually says. I’ve confirmed his findings by downloading the data myself and it sure seems that the minimum was on September 7th, and not the 10th:
He says on his blog:
The Arctic sea ice looks to have reached its minimum on the 7th September, which is four days earlier than average. The sea ice extent bottomed out at 4.083 million square kilometres making it the second lowest since records started in 1978 – well that’s according to the data file that I’ve just downloaded!
Strangely, according to the data that I download from the National Snow and Ice Data Center [NSIDC] the minimum occurred three days later on September 10th. As I said in my introduction on the 7th the value was 4.083, but according to the news item that I’ve included below, the value on the 10th was 4.14 million square kilometres and tied it with the year 2007, which according to the data file is third.\
All these daily values translate into the following chart with the minimum occurring on the seventh and not the tenth of September.
It is a puzzle. Perhaps whoever wrote the NSIDC press release looked at their 5 day average value in their Chartic interactive graph instead of the raw data? When using that tool, the data rounds up to 4.14 as you can see: