• Bess, T. D., , G. L. Smith, , and T. P. Charlock, 1989: A ten-year monthly data set of outgoing longwave radiation from Nimbus-6 and Nimbus-7 satellites. Bull. Amer. Meteor. Soc., 70 , 480489.

    • Search Google Scholar
    • Export Citation
  • Byers, H. R., , and R. R. J. Braham, 1949: The Thunderstorm. U.S. Government Printing Office, 287 pp.

  • Chelliah, M., , and P. Arkin, 1992: Large-scale interannual variability of monthly outgoing longwave radiation anomalies over the global tropics. J. Climate, 5 , 371389.

    • Search Google Scholar
    • Export Citation
  • Collimore, C. C., , M. H. Hitchman, , and D. W. Martin, 1998: Is there a quasi-biennial oscillation in tropical deep convection? Geophys. Res. Lett., 25 , 333336.

    • Search Google Scholar
    • Export Citation
  • Curtis, C., , and R. Adler, 2000: ENSO indices based on patterns of satellite-derived precipitation. J. Climate, 13 , 27862793.

  • Earth Radiation Budget Experiment Data Management System, 1994: The regional, zonal, and global averages, S-4/S-4N user's guide. NASA Langley Research Center Distributed Active Archive Center, 65 pp.

    • Search Google Scholar
    • Export Citation
  • Gage, K. S., , and G. C. Reid, 1987: Longitudinal variations in tropical tropopause properties in relation to tropical convection and El Niño–Southern Oscillation events. J. Geophys. Res., 92 , 1419714203.

    • Search Google Scholar
    • Export Citation
  • Gagin, A., , D. Rosenfeld, , and R. E. Lopez, 1985: The relationship between height and precipitation characteristics of summertime convective cells in South Florida. J. Atmos. Sci., 42 , 8494.

    • Search Google Scholar
    • Export Citation
  • Garcia, O., 1985: Atlas of Highly Reflective Clouds for the Global Tropics: 1971–1983. U.S. Department of Commerce, 365 pp. [Available from Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402.].

    • Search Google Scholar
    • Export Citation
  • Gray, W. M., , J. D. Scheaffer, , and J. A. Knaff, 1992: Influence of the stratospheric QBO on ENSO variability. J. Meteor. Soc. Japan, 70 , 975995.

    • Search Google Scholar
    • Export Citation
  • Grossman, R., , and O. Garcia, 1990: The distribution of deep convection over ocean and land during the Asian summer monsoon. J. Climate, 3 , 10321044.

    • Search Google Scholar
    • Export Citation
  • Gruber, A., , and A. F. Krueger, 1984: The status of the NOAA outgoing longwave radiation data set. Bull. Amer. Meteor. Soc., 65 , 958962.

    • Search Google Scholar
    • Export Citation
  • Hastenrath, S., 1990: The relationship of highly reflective clouds to tropical climate anomalies. J. Climate, 3 , 353365.

  • Huesmann, A. S., , and M. H. Hitchman, 2001: The stratospheric quasi-biennial oscillation in the NCEP reanalyses: Climatological structures. J. Geophys. Res., 106 , 1185911874.

    • Search Google Scholar
    • Export Citation
  • Kalnay, E., and Coauthors. 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Amer. Meteor. Soc., 77 , 437471.

  • Kilonsky, B., , and C. S. Ramage, 1976: A technique for estimating tropical open-ocean rainfall from satellite observations. J. Appl. Meteor., 15 , 972975.

    • Search Google Scholar
    • Export Citation
  • Kistler, R., and Coauthors. 2001: The NCEP–NCAR 50-year reanalysis: Monthly means CD-ROM and documentation. Bull. Amer. Meteor. Soc., 82 , 247267.

    • Search Google Scholar
    • Export Citation
  • Knaff, J. A., 1993: Evidence of a stratospheric QBO modulation of tropical convection. Dept. of Atmospheric Science, Colorado State University, Fort Collins, CO, Paper 520, 91 pp.

    • Search Google Scholar
    • Export Citation
  • Knox, J. A., 1997: Generalized nonlinear balance criteria and inertial stability. J. Atmos. Sci., 54 , 967985.

  • Kyle, H. L., , P. E. Ardanuy, , and R. R. Hucek, 1986: El Niño and Outgoing Longwave Radiation: An Atlas of Nimbus-7 Earth Radiation Budget Observations. NASA Reference Publ. 1163, 98 pp.

    • Search Google Scholar
    • Export Citation
  • Lucas, L. E., , D. E. Waliser, , P. Xie, , J. E. Janowiak, , and B. Liebmann, 2001: Estimating the satellite equatorial crossing time biases in the daily, global outgoing longwave radiation dataset. J. Climate, 14 , 25832605.

    • Search Google Scholar
    • Export Citation
  • Mapes, B. E., 1993: Gregarious tropical convection. J. Atmos. Sci., 50 , 20262037.

  • Mecikalski, J. R., , and G. J. Tripoli, 2003: Influence of upper tropospheric inertial stability on the convective transport of momentum. Quart. J. Roy. Meteor. Soc., in press.

    • Search Google Scholar
    • Export Citation
  • Montgomery, M. T., , and B. F. Farrell, 1993: Tropical cyclone formation. J. Atmos. Sci., 50 , 285310.

  • Plumb, R. A., , and R. C. Bell, 1982: A model of the quasi-biennial oscillation on an equatorial beta-plane. Quart. J. Roy. Meteor. Soc., 108 , 335352.

    • Search Google Scholar
    • Export Citation
  • Randel, W. J., , F. Wu, , and D. J. Gaffen, 2000: Interannual variability of the tropical tropopause derived from radiosonde data and NCEP reanalyses. J. Geophys. Res., 105 , 1550915523.

    • Search Google Scholar
    • Export Citation
  • Reid, G. C., , and K. S. Gage, 1981: On the annual variation in height of the tropical tropopause. J. Atmos. Sci., 38 , 19281938.

  • Reid, G. C., , and K. S. Gage, 1985: Interannual variations in the height of the tropical tropopause. J. Geophys. Res., 90 , 56295635.

  • Rosenfeld, D., , and A. Gagin, 1989: Factors governing the total rainfall yield from continental convective clouds. J. Appl. Meteor., 28 , 10151030.

    • Search Google Scholar
    • Export Citation
  • Trepte, C. R., 1993: Tracer transport in the lower stratosphere. Ph.D. dissertation, University of Wisconsin—Madison, 169 pp.

  • Tung, K. K., , and H. Yang, 1994: Global QBO in circulation and ozone. Part I: Reexamination of observational evidence. J. Atmos. Sci., 51 , 26992707.

    • Search Google Scholar
    • Export Citation
  • Ulanski, S. L., , and M. Garstang, 1978: The role of surface divergence and vorticity in the life cycle of convective rainfall. Part I: Observation and analysis. J. Atmos. Sci., 35 , 10471062.

    • Search Google Scholar
    • Export Citation
  • Waliser, D. E., , and W. Zhou, 1997: Removing satellite equatorial crossing time biases from the OLR and HRC datasets. J. Climate, 10 , 21252146.

    • Search Google Scholar
    • Export Citation
  • Waliser, D. E., , N. E. Graham, , and C. Gautier, 1993: Comparison of the highly reflective cloud and outgoing longwave radiation datasets for use in estimating tropical deep convection. J. Climate, 6 , 331353.

    • Search Google Scholar
    • Export Citation
  • Wallace, J. M., , E. M. Rasmusson, , T. P. Mitchell, , V. E. Kousky, , E. S. Sarachik, , and H. von Storch, 1998: On the structure and evolution of ENSO-related climate variability in the tropical Pacific: Lessons from TOGA. J. Geophys. Res., 103 , 1424114259.

    • Search Google Scholar
    • Export Citation
  • Wang, B., 1994: Climatic regimes of tropical convection and rainfall. J. Climate, 7 , 11091118.

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On The Relationship between the QBO and Tropical Deep Convection

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  • 1 Department of Atmospheric and Oceanic Sciences, University of Wisconsin—Madison, Madison, Wisconsin
  • | 2 Space Science and Engineering Center, University of Wisconsin—Madison, Madison, Wisconsin
  • | 3 Department of Atmospheric and Oceanic Sciences, University of Wisconsin—Madison, Madison, Wisconsin
  • | 4 Institute for Terrestrial and Planetary Atmospheres, State University of New York at Stony Brook, Stony Brook, New York
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Abstract

The height and amount of tropical deep convection are examined for a correlation with the stratospheric quasi-biennial oscillation (QBO). A new 23-yr record of outgoing longwave radiation (OLR) and a corrected 17-yr record of the highly reflective cloud (HRC) index are used as measures of convection. When binned by phase of the QBO, zonal means and maps of OLR and HRC carry a QBO signal. The spatial patterns of the maps highlight the QBO signal of OLR and HRC in typically convective regions. Spectral analysis of zonal mean OLR and HRC near the equator reveals significant peaks at QBO frequencies. Rotated empirical orthogonal function (REOF) analysis is used to determine if ENSO variations of convection are aliased into the observed QBO signals. Some analyses are repeated using the OLR record after ENSO REOF modes have been removed, yielding very similar results compared to the original analyses. It appears that the QBO signal is distinct from the ENSO signal, although the relative brevity of the OLR and HRC records with respect to the ENSO cycle makes assessing the impact of ENSO difficult.

Three mechanisms that can link the QBO with deep convection are investigated: 1) the QBO modulation of tropopause height may allow convection to penetrate deeper in some years compared to other years; 2) the QBO modulation of lower-stratospheric to upper-tropospheric zonal wind shear may result in cloud tops being “sheared off” more in some years than in other years; 3) the QBO modulation of upper-tropospheric relative vorticity may relax dynamic constraints on cloud-top outflow and thus allow more cloud growth in some years compared to other years. Measures of these mechanisms—tropopause pressure and temperature, 50–200-hPa zonal wind shear (cross-tropopause shear), and 150-hPa vorticity, all from the NCEP reanalyses—are compared to OLR and HRC. QBO fluctuations of convection are generally well correlated with QBO fluctuations of tropopause height. In regions where these height fluctuations are relatively small, convective fluctuations are well correlated with QBO variations of cross-tropopause shear, especially during boreal summer and winter when convection is concentrated away from the equator and the largest tropopause height fluctuations. In fact, during summer the shear mechanism appears to dominate such that QBO-related convective behavior is different than during the other seasons. QBO convective behavior is uncorrelated with vorticity fluctuations near the tropopause.

A secondary component of this study is the description of a new, long-term OLR dataset. Using measurements from Nimbus-6, Nimbus-7, and the Earth Radiation Budget Satellite (ERBS), the 23-yr OLR record analyzed in this study was constructed. This record has fewer interannual biases due to satellite differences than the well-known NOAA OLR record and, therefore, is more useful for studies of interannual meteorological variations.

Corresponding author address: Christopher C. Collimore, Dept. of Atmospheric and Oceanic Sciences, University of Wisconsin—Madison, 1225 W. Dayton St., Madison, WI 53706. Email: cccollim@wisc.edu

Abstract

The height and amount of tropical deep convection are examined for a correlation with the stratospheric quasi-biennial oscillation (QBO). A new 23-yr record of outgoing longwave radiation (OLR) and a corrected 17-yr record of the highly reflective cloud (HRC) index are used as measures of convection. When binned by phase of the QBO, zonal means and maps of OLR and HRC carry a QBO signal. The spatial patterns of the maps highlight the QBO signal of OLR and HRC in typically convective regions. Spectral analysis of zonal mean OLR and HRC near the equator reveals significant peaks at QBO frequencies. Rotated empirical orthogonal function (REOF) analysis is used to determine if ENSO variations of convection are aliased into the observed QBO signals. Some analyses are repeated using the OLR record after ENSO REOF modes have been removed, yielding very similar results compared to the original analyses. It appears that the QBO signal is distinct from the ENSO signal, although the relative brevity of the OLR and HRC records with respect to the ENSO cycle makes assessing the impact of ENSO difficult.

Three mechanisms that can link the QBO with deep convection are investigated: 1) the QBO modulation of tropopause height may allow convection to penetrate deeper in some years compared to other years; 2) the QBO modulation of lower-stratospheric to upper-tropospheric zonal wind shear may result in cloud tops being “sheared off” more in some years than in other years; 3) the QBO modulation of upper-tropospheric relative vorticity may relax dynamic constraints on cloud-top outflow and thus allow more cloud growth in some years compared to other years. Measures of these mechanisms—tropopause pressure and temperature, 50–200-hPa zonal wind shear (cross-tropopause shear), and 150-hPa vorticity, all from the NCEP reanalyses—are compared to OLR and HRC. QBO fluctuations of convection are generally well correlated with QBO fluctuations of tropopause height. In regions where these height fluctuations are relatively small, convective fluctuations are well correlated with QBO variations of cross-tropopause shear, especially during boreal summer and winter when convection is concentrated away from the equator and the largest tropopause height fluctuations. In fact, during summer the shear mechanism appears to dominate such that QBO-related convective behavior is different than during the other seasons. QBO convective behavior is uncorrelated with vorticity fluctuations near the tropopause.

A secondary component of this study is the description of a new, long-term OLR dataset. Using measurements from Nimbus-6, Nimbus-7, and the Earth Radiation Budget Satellite (ERBS), the 23-yr OLR record analyzed in this study was constructed. This record has fewer interannual biases due to satellite differences than the well-known NOAA OLR record and, therefore, is more useful for studies of interannual meteorological variations.

Corresponding author address: Christopher C. Collimore, Dept. of Atmospheric and Oceanic Sciences, University of Wisconsin—Madison, 1225 W. Dayton St., Madison, WI 53706. Email: cccollim@wisc.edu

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