Changes in water vapor transports of the ascending\ud branch of the tropical circulation

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Zahn, Matthias ; Allan, Richard (2011)

Recent studies have found contradicting results on whether tropical atmospheric circulation (TAC) has intensified or weakened in recent decades. We here re-investigate recent changes in TAC derived from moisture transports into the tropics using high temporal and spatial resolution reanalyses from ERA-interim.\ud We found a significant strengthening of both, the lower level inward transports and the mid level outward transports over the recent two decades. However the signal in the total budget is weak, because strengthening of the in and outflow neutralize each other, at least to some extent. We found atmospheric humidity to be relatively stable, so suggest that the intensification is mainly caused by an intensification of the wind related circulation strength.\ud The exact quantitative values were found to heavily depend on whether the calculations are based on mean or instantaneous values. We highlight the importance for using the instantaneous ones for transport calculations, as they represent the coincidence of high wind speeds and high atmospheric humidity.
  • References (29)
    29 references, page 1 of 3

    Allan, R. P., and B. J. Soden (2007), Large discrepancy between observed and simulated precipitation trends in the ascending and descending branches of the tropical circulation, Geophys. Res. Lett., 34, L18705, doi:10.1029/2007GL031460.

    Allan, R. P., and B. J. Soden (2008), Atmospheric warming and the amplification of precipitation extremes, Science, 321, 1481-1484.

    Allan, R. P., B. J. Soden, V. O. John, W. Ingram, and P. Good (2010), Current changes in tropical precipitation, Environ. Res. Lett., 5, 025205, doi:10.1088/1748-9326/5/2/025205.

    Allen, M. R., and W. J. Ingram (2002), Constraints on future changes in climate and the hydrologic cycle, Nature, 419, 224-232.

    Bengtsson, L., K. I. Hodges, S. Koumoutsaris, M. Zahn, and N. Keenlyside (2011), The changing atmospheric water cycle of the polar regions in a warmer climate, Tellus, Ser. A, doi:10.1111/j.1600-0870.2011.00534.x.

    Bigg, G. R. (2006), Comparison of coastal wind and pressure trends over the tropical Atlantic: 1946-1987, Int. J. Climatol., 13, 411-421.

    Chou, C., J.‐Y. Tu, and P.‐H. Tan (2007), Asymmetry of tropical precipitation change under global warming, Geophys. Res. Lett., 34, L17708, doi:10.1029/2007GL030327.

    Dee, D. P., and S. Uppala (2009), Variational bias correction of satellite radiance data in the ERA‐Interim reanalysis, Q. J. R. Meteorol. Soc., 135, 1830-1841.

    Dee, D. P., et al. (2011), The ERA‐Interim reanalysis: Configuration and performance of the data assimilation system, Q. J. R. Meteorol. Soc., 137, 553-597.

    Gastineau, G., and B. J. Soden (2011), Evidence for a weakening of tropical surface wind extremes in response to atmospheric warming, Geophys. Res. Lett., 38, L09706, doi:10.1029/2011GL047138.

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