Articles | Volume 8, issue 2
Earth Syst. Sci. Data, 8, 461–490, 2016

Special issue: Water vapour in the upper troposphere and middle atmosphere:...

Earth Syst. Sci. Data, 8, 461–490, 2016

  28 Sep 2016

28 Sep 2016

The Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database: a long-term database for climate studies

Sean M. Davis1,2, Karen H. Rosenlof1, Birgit Hassler1,2, Dale F. Hurst1,2, William G. Read3, Holger Vömel4, Henry Selkirk5,6, Masatomo Fujiwara7, and Robert Damadeo8 Sean M. Davis et al.
  • 1NOAA Earth Systems Research Laboratory (ESRL), Boulder, CO, USA
  • 2Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado at Boulder, Boulder, CO, USA
  • 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
  • 4National Center for Atmospheric Research, Boulder, CO, USA
  • 5NASA Goddard Space Flight Center, Greenbelt, MD, USA
  • 6Universities Space Research Association, Columbia, MD, USA
  • 7Hokkaido University, Sapporo, Japan
  • 8NASA Langley Research Center, Hampton, VA, USA

Abstract. In this paper, we describe the construction of the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database, which includes vertically resolved ozone and water vapor data from a subset of the limb profiling satellite instruments operating since the 1980s. The primary SWOOSH products are zonal-mean monthly-mean time series of water vapor and ozone mixing ratio on pressure levels (12 levels per decade from 316 to 1 hPa). The SWOOSH pressure level products are provided on several independent zonal-mean grids (2.5, 5, and 10°), and additional products include two coarse 3-D griddings (30° long  ×  10° lat, 20°  ×  5°) as well as a zonal-mean isentropic product. SWOOSH includes both individual satellite source data as well as a merged data product. A key aspect of the merged product is that the source records are homogenized to account for inter-satellite biases and to minimize artificial jumps in the record. We describe the SWOOSH homogenization process, which involves adjusting the satellite data records to a “reference” satellite using coincident observations during time periods of instrument overlap. The reference satellite is chosen based on the best agreement with independent balloon-based sounding measurements, with the goal of producing a long-term data record that is both homogeneous (i.e., with minimal artificial jumps in time) and accurate (i.e., unbiased). This paper details the choice of reference measurements, homogenization, and gridding process involved in the construction of the combined SWOOSH product and also presents the ancillary information stored in SWOOSH that can be used in future studies of water vapor and ozone variability. Furthermore, a discussion of uncertainties in the combined SWOOSH record is presented, and examples of the SWOOSH record are provided to illustrate its use for studies of ozone and water vapor variability on interannual to decadal timescales. The version 2.5 SWOOSH data are publicly available at doi:10.7289/V5TD9VBX.

Short summary
This paper describes the construction of the Stratospheric Water and Ozone Satellite Homogenized (SWOOSH) database, whose main feature is a combined data product created by homogenizing multiple satellite records. This motivation for SWOOSH is that in order to study multiyear to decadal variability in ozone and water vapor concentrations, it is necessary to have a continuous and smooth record without artificial jumps in the data.