from: https://www.ncdc.noaa.gov/data-access/weather-balloon/radiosonde-atmospheric-temperature-products-accessing-climate RATPAC Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) are datasets created through a collaborative effort involving NOAA scientists from the Air Resources Laboratory, the Geophysical Fluid Dynamics Laboratory, and NCEI. Observations in the dataset are collected by hydrogen-filled weather balloons that carry a radiosonde up in the air to measure variables including temperature, humidity, and atmospheric pressure. RATPAC data come from 85 stations with near-global coverage. NCEI provides data on 13 atmospheric pressure levels: the surface, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50, and 30 mb. Where available, data begin in 1958 and extend through the present. Some of the 85 stations have discontinued observations since the 1990s, and not all stations have observations at all levels. RATPAC-A Radiosonde Atmospheric Temperature Products for Assessing Climate dataset A (RATPAC-A) contains adjusted global, hemispheric, tropical, and extratropical mean temperature anomalies. ​A collaborative effort by NOAA scientists collected observations at 85 stations using hydrogen-filled weather balloons equipped with a radiosonde, providing data from 13 atmospheric pressure levels and at near-global coverage. RATPAC-A is one of two distinct datasets that emerged from a need for a radiosonde time series that was less influenced by inhomogeneities. Scientists used a procedure called first differencing to reduce the inhomogeneities in this dataset. From 1958 through 1995, the bases of RATPAC-A are on spatial averages of the Lanzante et al. (2003; hereafter LKS) adjusted 87-station temperature data. After 1995, they are based on the Integrated Global Radiosonde Archive (IGRA) station data, combined using a first difference method (Free et al. 2004). For analyses of interannual and longer-term changes in global, hemispheric, and tropical means, the NOAA team recommends using RATPAC-A because it contains the most robust large-scale averages. Access to the RATPAC-A data files is available on the FTP site. Spatial Averaging In an effort to obtain spatially unbiased large-scale means, the team compensates for uneven longitudinal distribution of stations by creating regional means before averaging data into zonal bands. Each 30-degree zonal band was divided into three longitudinal regions of 120 degrees each: 30°W to 90°E, 90°E to 150°W, and 150°W to 30°W. Hemispheric (0°–90°), tropical (30°S–30°N), and extratropical (30°–90°) means were calculated from these zonal means, alreally weighted using the cosine of the latitude of the midpoint of the zone and the global mean was the average of the hemispheric means. To facilitate comparison with other datasets, NCEI provides the time series for the region from 20°N to 20°S. Endpoint Outlier Trimming The FD procedure introduced an endpoint outlier trimming procedure to reduce the random errors. As described in Peterson et al. (1998) and Free et al. (2004), this procedure removes data exceeding a prescribed multiple of the standard deviation of the original time series if the data fall at the end of a data segment (immediately before or after a gap). Using a larger multiple as a cutoff rather than a smaller multiple, the removal of fewer data points occurs. Results from the FD procedure are sensitive to the choice of this multiple, or trim factor (see Free et al. 2005). For the reasons outlined in that paper, the team chose a factor equal to one standard deviation from the mean. Interpolation In another effort to reduce random errors, the LKS authors used linear interpolation between months of data to fill data gaps of less than four months before removing data at the times of metadata events. The use of interpolation is only at stations where data removal occurred due to metadata events. The mean number of months of data added by interpolation to these 38 stations was about six per station. References Free M., D.J. Seidel, J.K. Angel, J. Lanzante, I. Durre and T.C. Peterson, 2005: Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series. Journal of Geophysical Research, 110, D22101, http://dx.doi.org/10.1029/2005JD006169 (link is external). Free, M., J.K. Angel, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel, 2004: Using first differences to reduce inhomogeneity in radiosonde temperature datasets. Journal of Climate, 17, 4171-4179, http://dx.doi.org/10.1175/JCLI3198.1 (link is external). Lanzante, J.R., S.A. Klein, and D.J. Seidel, 2003: Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology. Journal of Climate, 16, 224-240, http://dx.doi.org/10.1175/1520-0442(2003)016<0224:THOMRT>2.0.CO;2 (link is external). Peterson, T.C., T.R. Karl, P.F. Jamason, R. Knight, and D.R. Easterling, 1998: First difference method: Maximizing station density for the calculation of long-term global temperature change. Journal of Geophysical Research Atmospheres, 103, 25967-25974, http://dx.doi.org/0.1029/98JD01168 (link is external). RATPAC-B Radiosonde Atmospheric Temperature Products for Assessing Climate dataset B (RATPAC-B) contains data for individual stations, as well as large-scale arithmetic averages corresponding to areas used for RATPAC-B. ​A collaborative effort by NOAA scientists collected observations at 85 stations using hydrogen-filled weather balloons equipped with a radiosonde, providing data from 13 atmospheric pressure levels and near-global coverage. RATPAC-B is one of two distinct datasets that emerged from a need for a radiosonde time series that was less influenced by inhomogeneities. The station data consist of adjusted data produced by Lanzante et al. (2003; hereafter LKS) for the period 1958–1997 and unadjusted data from the Integrated Global Radiosonde Archive (IGRA) after 1997. The regional mean time series in RATPAC-B are based on arithmetic averaging of these station data, rather than the first difference method used to create RATPAC-A. Readme.txt: Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC) Readme file - December 2005 This file lists the contents of the RATPAC ftp directory and describes the format of the various files available. For additional information about RATPAC, see http://www.ncdc.noaa.gov/oa/cab/ratpac/index.php. Note that the directory v2beta contains RATPAC files whose underlying IGRA data originate from IGRA v2beta. The directory structure and file format of the RATPAC v2beta files are the same as for RATPAC v1. http://www1.ncdc.noaa.gov/pub/data/igra/v2beta/igra2-readme.txt . Contents of ftp://ftp.ncdc.noaa.gov/pub/data/ratpac Directories: ratpac-a Output files for RATPAC-A ratpac-b Output files for RATPAC-B v2beta RATPAC files based on IGRA v2beta Files: ratpac-stations.txt List of stations used in the RATPAC project ratpac-countries.txt List of country codes used in the RATPAC station list readme.txt This file status.txt Notes on the current status of the online files Format Description of RATPAC Data Files: 1. 'RATPAC-A-annual-levels.txt': Annual mean temperature anomalies for 7 regions -- hemispheres, globe,tropics (30n-30S), extratropics and 20N-20S, for 13 pressure levels from the surface to 30 mb. Pressure levels are surface, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50 and 30 mb. 999.00 denotes missing data. Headers: Data for each of the 7 regions appears after a two-line header containing: Line 1: Name of the region Line 2: column headings for the data Data format: Variable Name Columns Description -------------------- ------- ----------- year 1-4 Year, starting in 1958 surface temp 5-11 Temperature anomaly at surface, K temperature 12-95 Temperature anomalies at 12 pressure levels, each as Fortran format f7.2, in K 2. 'RATPAC-A-seasonal-layers.txt': Seasonal mean temperature anomalies for the globe, hemispheres, tropics, extratropics and 20N-20S, for three atmospheric layers: 850-300 mb, 300-100 mb, and 100-50 mb. 999.00 denotes missing data. Headers: Data for each of the 7 regions appears after a two-line header containing: Line 1: Name of the atmospheric layer Line 2: column headings for the data Data format: Variable Name Columns Description -------------------- ------- ----------- year 1-4 Year, starting in 1958 seas 5-8 Season, with 1=DJF, 2=MAM, 3=JJA, 4=SON temperature 9-57 Temperature anomalies for 7 regions, each as Fortran format f7.2, in K 3. 'RATPAC-B-monthly-combined.txt': Monthly mean temperature anomalies (means of 0Z and 12Z observations) for 13 pressure levels from the surface to 30 mb, for 85 stations. Station data are listed in order of WMO station ID, found in the file 'ratpac-stations.txt'. Pressure levels are surface, 850, 700, 500, 400, 300, 250, 200, 150, 100, 70, 50 and 30 mb. 999.00 denotes missing data. Data format: Variable Name Columns Description -------------------- ------- ----------- station number 1-3 Number from 1-85 denoting the rank of the station in the 85-station set blank 4 year 5-8 Year, starting in 1958 month 9-12 Number of the month (January=1, etc.) temperature 13-103 Temperature anomalies for 13 levels, in K, each as Fortran format f7.2 blank 104-106 station ID 107-111 WMO station ID number 4. 'RATPAC-B-monthly-00Z.txt': Monthly mean temperature anomalies for 00Z for 13 pressure levels from the surface to 30 mb, for 85 stations. Station data are listed in the station order found in the file 'ratpac-stations.txt'. Format is the same as for RATPAC-B-monthly-combined.txt, described above. 5. 'RATPAC-B-monthly-12Z.txt': Monthly mean temperature anomalies for 12Z for 13 pressure levels from the surface to 30 mb, for 85 stations. Station data are listed in the station order found in the file 'ratpac-stations.txt'. Format is the same as for RATPAC-B-monthly-combined.txt, described above. 6. 'RATPAC-B-annual-regions.txt': Annual mean temperature anomalies for the globe, hemispheres, tropics and extratropics, plus 30-degree zonal bands from 60-90 N to 60-90 S, for 13 pressure levels from the surface to 30 mb, based on RATPAC-B station data. 999.00 denotes missing data. Headers: Data for each of the regions appears after a two-line header containing: Line 1: Name of the region Line 2: column headings for the data Data format: Variable Name Columns Description -------------------- ------- ----------- year 1-4 Year, starting in 1958 surface temp 5-11 Temperature anomaly at surface, K temperature 12-95 Temperature anomalies at 12 pressure levels, each as Fortran format f7.2, in K 7. 'ratpac-stations.txt': Station list of the 85 stations whose data are used in RATPAC A and B. Format: Variable Name Columns Description -------------------- ------- ----------- Name 1-16 Station name Country 18-19 FIPS country code Latitude 24-29 Latitude, decimal degrees Longitude 31-37 Longitude, decimal degrees Elevation 40-43 Elevation, m Station ID 45-49 WMO station identifier Obs. times 52-62 Observation times used to create monthly temperature anomalies 8. 'ratpac-countries.txt': List of country codes used by RATPAC Format: Variable Name Columns Description -------------------- ------- ----------- Country code 1-2 FIPS country code Country name 5-44 FIPS country name ------ fz 25.3.16