Arctic tropospheric warming amplification?
Relative rates of temperature change between the troposphere and surface, and the mechanisms that produce these changes, have long been a contentious issue. Graversen et al., predicated upon the ERA-40 reanalysis, report polar tropospheric amplification of surface warming and attempt to explain this finding dynamically. Here we show (1) that data from satellites and weather balloons indicate that the ERA-40 trends are increasingly unrealistic polewards of 62 degrees N; (2) that the two other reanalyses considered exhibit very different polar trends; and (3) that the vertical profile of polar trends in ERA-40 is unrealistic, particularly above the troposphere. These quasi-independent strands of evidence imply that the pattern of warming in the Arctic troposphere is highly unlikely to be as given in ERA-40 and as reported by Graversen et al..
Thorne
Peter W
PW
Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK. peter.thorne@metoffice.gov.uk