ANNUAL AND SEASONAL TROPOSPHERIC TEMPERATURE TREND COMPARISONS OF RADIOSONDE AND REANALYSIS DATA AT REGIONAL SCALES

摘要

Data from global reanalyses are routinely used as initial and lateral boundary conditions for regional numerical weather prediction modeling. Reanalyses have also been used for longer term assessments of tropospheric temperature trends. Our study compares linear tropospheric temperature trend estimates for radiosonde and reanalysis data, both annually and seasonally, at land-based sites in the Americas and Australasia/Oceania from 1979-2001 in order to assess the quantitative agreement between the two types of data. In our analyses, we found that the average radiosonde trends generally fell in between the average reanalysis trend values and indicate that reanalyses are indeed appropriate to use for climate trend analysis. The most significant differences between the radiosonde and reanalysis datasets occurred during the Northern Hemisphere growing season (April - September], and at upper levels of the troposphere (200 and 300 mb). The semiannual variations in the significance of the reanalysis-radiosonde average temperature trend differences may be indicative of regional variations in these differences. Additional reanalysis-radiosonde comparisons using newer radiosonde datasets that have more global coverage are recommended to further investigate such regional patterns and better understand global properties of these trend differences.