U of T researchers find error in Arctic snow cover data

A University of Toronto analysis published in Science Advances finds that changes in NOAA instruments and methods made satellite records appear to show more autumn snow cover, while the corrected record indicates a decline in Northern Hemisphere autumn snow extent.

University of Toronto atmospheric physicists report an error in a long-running NOAA record of Northern Hemisphere autumn snow cover. The NOAA dataset has been used in climate assessments, including IPCC reports, and is based on satellite observations dating back to the 1960s. The U of T team, with co-authors including Paul Kushner and researchers from Environment and Climate Change Canada, published their reanalysis in the journal Science Advances and attribute the discrepancy to evolving instrumentation and processing that increased sensitivity to thin snow. Key findings: - NOAA’s original series showed an increase in autumn snow cover of about 1.5 million square kilometres per decade. - The reanalysis by the U of T team shows a decrease of about 0.5 million square kilometres per decade instead. - The team reports that changes in instruments and data collection made satellites more sensitive to thin snow, producing an artificial upward trend in the historical record. Summary: The study explains why the long-standing NOAA series suggested increasing autumn snow cover and presents a corrected trend that aligns with other observations indicating snow loss. Undetermined at this time.