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Radiosonde Atmospheric Temperature Products for Assessing Climate

RATPAC-B

Because the first difference ("FD") method used for RATPAC-A does not allow production of individual station time series, and to provide alternative large-scale mean time series for comparison with the FD time series, a set of updated station time series is also created by appending monthly mean station data from IGRA for 1997-present to the corresponding ("LIBCON") adjusted LKS station time series for 1958-1997 without any adjustment for inhomogeneities after 1997. Note that, as in RATPAC-A, the "LIBCON" subset, one of several available versions of the LKS adjusted data, was used since it is the version preferred by the LKS authors. We combine the 00Z and 12Z observations where both are available, and for consistency only those observation times from the IGRA data are used that were present in the LKS adjusted station data. (Station data for the two observation times are also available separately). To minimize the discontinuity at 1997, a factor equal to the difference between the means of the IGRA and LKS data for 1996-1997 is added to the IGRA monthly means. The effect is to shift the IGRA data so that the means of the two datasets for the last two years of the LKS time series are equal. If both time series are present for fewer than 9 months in those two years, the time period 1990-1997 is used instead.

At one or more levels at approximately 14 stations, LKS found a discontinuity, but deleted data after the discontinuity rather than adjusting it because adjustment was not feasible. In creating RATPAC-B, the IGRA data for those levels at those stations are not appended after 1997 to avoid reintroducing known inhomogeneities. Four of the possible 85 stations (Preobrazheniya, Chetyrekhstolbov, Mould Bay and Ashabad) have no data after 1997, and so are not extended. Four other stations (Abidjan, Honiara, Bellingshausen and Molodezhnaya) have closed since 1997.

The result is a set of station time series for 1958 through present that have been adjusted through 1997 but not afterwards. Hemispheric, global, tropical and extratropical means created from these station time series are available for comparison with RATPAC-A.


http://ncdc.noaa.gov/oa/climate/ratpac/index.php
Created by Jon.Burroughs@noaa.gov
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Last Updated Wednesday, 20-Aug-2008 12:11:36 EDT by Jon.Burroughs@noaa.gov
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