Arctic Sea Ice Underestimated for Weeks Due to Faulty Sensor
By Alex Morales, Bloomberg.com news, Feb 20, 2009 [here]
A glitch in satellite sensors caused scientists to underestimate the extent of Arctic sea ice by 500,000 square kilometers (193,000 square miles), a California- size area, the U.S. National Snow and Ice Data Center said.
The error, due to a problem called “sensor drift,” began in early January and caused a slowly growing underestimation of sea ice extent until mid-February. That’s when “puzzled readers” alerted the NSIDC about data showing ice-covered areas as stretches of open ocean, the Boulder, Colorado-based group said on its Web site.
“Sensor drift, although infrequent, does occasionally occur and it is one of the things that we account for during quality- control measures prior to archiving the data,” the center said. “Although we believe that data prior to early January are reliable, we will conduct a full quality check.” … [more]
Note: the glitch was reported by Joseph D’Aleo of ICECAP on Feb 15 [here]. The story was then picked up by Anthony Watts of Watts Up With That on Feb. 16 [here]. After these citizen scientist bloggers informed the NSIDC, the Center discovered the satellite sensor had problems and issued a statement that was reported at Watts Up With That on Feb 18 [here].
Bloomberg’s report is thus 4 or 5 days late and fails to credit D’Aleo and Watts for their vital roles in all this. Citizen bloggers Anthony Watts and Steve McIntire of Climate Audit also uncovered and reported on data defects in an article in Nature last month about Antarctic temperature trends [here].