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Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC)

Photo of Army Air Force meteorologists preparing to launch a weather balloon
Army Air Force meteorologists prepare to launch a hydrogen-filled balloon that will carry a radiosonde up in the air to measure temperature, humidity, and atmospheric pressure and transmit the data back to a ground station. Courtesy of the NOAA Photo Library.

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.

The temporal homogeneity of many radiosonde time series is questionable due to historical changes in instruments and measurement practices. This may make them unsuitable for the study of long-term climate variations, such as through trend analysis. The goal of researchers was to create time series from radiosonde temperatures that are less influenced by the inhomogeneities. Two distinct datasets, RATPAC-A and RATPAC-B, were derived using different approaches to meet this need based largely in part on the Temporal Homogenization of Monthly Radiosonde Temperature Data (LKS) bias-adjusted dataset.

Products

  • RATPAC-A
    RATPAC-A contains adjusted global, hemispheric, tropical, and extratropical mean temperature anomalies. From 1958 through 1995, the bases of the data are on spatial averages of 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 team recommends use of RATPAC-A since it contains the most robust large-scale averages. 
  • RATPAC-B
    RATPAC-B contains data for individual stations as well as large-scale arithmetic averages corresponding to areas used for RATPAC-A. The station data consist of adjusted data produced by LKS for the period 1958–1997 and unadjusted data from 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. For individual station data, monthly data, or regional means on smaller scales, the team recommends use of RATPAC-B, with careful attention paid to the potential of inhomogeneities influencing analysis after 1997.

For analyses that require data not included in RATPAC and that are less sensitive to long-term biases, consider the Integrated Global Radiosonde Archive (IGRA).

Data Access

The team recommends that you review the readme file prior to downloading the data as it describes all file information, documentation, and locations. Both RATPAC-A and RATPAC-B are available at the FTP and HTTP links.

  • FTP
    Download ASCII versions of the RATPAC data from our access area. This type of access is for individuals who have experience with FTP and programming languages.
  • HTTP
    Download ASCII versions of the RATPAC data from our access area.

References

Free M., D.J. Seidel, J.K. Angel, J. Lanzante, I. Durre and T.C. Peterson, 2005: Radiosonde Atmospheric Temperature Prodcuts 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.