The Earth's high-latitude regions are of critical importance in many climate-change scenarios, but a time continuous, spatially complete, and well-calibrated record of tropospheric temperatures is needed in order to assess past and future climate changes. Studies of recently compiled upper-air data sets show no evidence of CO2-induced warming, but the spatial pattern of tropospheric temperature variability in the Arctic has not been thoroughly examined. This study analyzes a 108-month segment of the data record from the TIROS Operational Vertical Sounder (TOVS) aboard NOAA polar-orbiting satellites to examine both the spatial and temporal variability of atmospheric temperature in the Arctic.
Temperature retrievals based on clear-column radiances archived at NOAA/NESDIS were done using algorithms tuned to Arctic conditions. The retrieved temperatures compared well with Arctic rawinsonde data, and include lowlevel inversions that are often problematic for satellite retrievals. The amplitude of the seasonal cycle in 500 mbar temperatures from the TOVS, NMC, and rawinsonde data generally agreed, whereas the phase comparisons produced mixed results. Principal component analyses of the TOVS and NMC temperatures revealed both monopole and dipole spatial patterns in the component loadings. Spatial patterns of the correlation between the upper-air data and the TOVS retrievals were similar to the principal component loading patterns. Whereas no significant trends were found in the station data for the same period as the TOVS record, a significant negative trend could be seen in the first principal component scores of the TOVS retrievals.