Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2016-1088
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
13 Jan 2017
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data
Jeremiah P. Sjoberg1,a, Thomas Birner1, and Richard H. Johnson1 1Department of Atmospheric Science, Colorado State University, Fort Collins, CO 80521
anow at: COSMIC Project Office, University Corporation for Atmospheric Research, Boulder, Colorado
Abstract. Observational estimates of Kelvin wave momentum fluxes in the tropical lower stratosphere remains challenging. Here we extend a method based on linear wave theory to estimate time series of these momentum fluxes from high-resolution radiosonde data. Testing the sensitivity to vertical resolution, our estimated momentum fluxes are found to be most sensitive to vertical resolution greater than 1 km, largely due to overestimation of the vertical wavelength. Estimates of momentum fluxes derived from reanalyses and coarse-resolution satellite data are notably larger. Daily time series are produced for sounding sites operated by the U.S. Department of Energy (DOE) and from the recent Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign. Our momentum flux estimates are found to be robust to different data sources and processing, and in quantitative agreement with estimates from prior studies. Climatological analysis is performed over the selected 11 year span of data from the ARM sites. Analyses for the available 11-year span of data reveal the expected seasonal cycle of momentum flux maxima in boreal winter and minima in boreal summer and variability associated with the quasi-biennial oscillation (QBO) of maxima during easterly phase and minima during westerly phase. Analysis of Madden-Julian Oscillation (MJO) active periods suggests that the MJO provides a nontrivial increase in lowermost stratospheric momentum fluxes, though statistical significance is not found due to the small number of events observed in the available time series.

Citation: Sjoberg, J. P., Birner, T., and Johnson, R. H.: Intraseasonal to interannual variability of Kelvin wave momentum fluxes as derived from high-resolution radiosonde data, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2016-1088, in review, 2017.
Jeremiah P. Sjoberg et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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RC1: 'Please see the attached PDF file', Anonymous Referee #3, 16 Jan 2017 Printer-friendly Version Supplement 
AC1: 'Author responses to reviewers', Jeremiah Sjoberg, 16 May 2017 Printer-friendly Version Supplement 
 
RC2: 'Referee comments', Anonymous Referee #1, 11 Feb 2017 Printer-friendly Version 
AC2: 'Author responses to reviewers', Jeremiah Sjoberg, 16 May 2017 Printer-friendly Version Supplement 
Jeremiah P. Sjoberg et al.
Jeremiah P. Sjoberg et al.

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Short summary
Observational estimates of tropical, large-scale fluxes of zonal momentum from troposphere to stratosphere remains challenging. Here we present an extended technique for estimating the amplitude of these momentum fluxes using data captured from balloon-borne radiosondes. Novel to our method is that we produce daily time series of momentum fluxes. Climatological analysis of these time series matches expectations of annual and interannual variability, indicating reliability in our estimates.
Observational estimates of tropical, large-scale fluxes of zonal momentum from troposphere to...
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