Trends in Antarctic Geopotential Height and Temperature: A Comparison between Radiosonde and NCEP–NCAR Reanalysis Data

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Abstract
A comparison of 40-yr (1960–99) trends in Antarctic geopotential height and temperature from quality controlled radiosonde observations and NCEP–NCAR reanalysis (NNR) data is undertaken. Observations from four Antarctic stations—having sufficiently long-term and consistent datasets—at four pressure levels (850, 500, 300, and 100 hPa) are utilized. The NNR reveals substantial negative trends in tropospheric geopotential height at high southern latitudes with no significant trends seen in the lower stratosphere above Antarctica. In contrast, observations indicate only minor negative trends in tropospheric height, while statistically significant decreases in height in the lower stratosphere have occurred over East Antarctica. However, both NNR and observations show a consistent, significant warming (∼1°C) in the lower troposphere (>500 hPa) above coastal Antarctica. At higher altitudes, trends derived from the two datasets diverge; the NNR fails to capture the marked cooling in the lower stratospher... Abstract A comparison of 40-yr (1960–99) trends in Antarctic geopotential height and temperature from quality controlled radiosonde observations and NCEP–NCAR reanalysis (NNR) data is undertaken. Observations from four Antarctic stations—having sufficiently long-term and consistent datasets—at four pressure levels (850, 500, 300, and 100 hPa) are utilized. The NNR reveals substantial negative trends in tropospheric geopotential height at high southern latitudes with no significant trends seen in the lower stratosphere above Antarctica. In contrast, observations indicate only minor negative trends in tropospheric height, while statistically significant decreases in height in the lower stratosphere have occurred over East Antarctica. However, both NNR and observations show a consistent, significant warming (∼1°C) in the lower troposphere (>500 hPa) above coastal Antarctica. At higher altitudes, trends derived from the two datasets diverge; the NNR fails to capture the marked cooling in the lower stratospher...