• Adames, Á. F., and J. M. Wallace, 2014: Three-dimensional structure and evolution of the MJO and its relation to the mean flow. J. Atmos. Sci., 71, 20072026, doi:10.1175/JAS-D-13-0254.1.

    • Search Google Scholar
    • Export Citation
  • Ferranti, L., T. N. Palmer, F. Molteni, and E. Klinker, 1990: Tropical-extratropical interaction associated with the 30–60 day oscillation and its impact on medium and extended range prediction. J. Atmos. Sci., 47, 21772199, doi:10.1175/1520-0469(1990)047<2177:TEIAWT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Gill, A. E., 1980: Some simple solutions for heat-induced tropical circulation. Quart. J. Roy. Meteor. Soc., 106, 447462, doi:10.1002/qj.49710644905.

    • Search Google Scholar
    • Export Citation
  • Haertel, P., K. Straub, and A. Budsock, 2015: Transforming circumnavigating Kelvin waves that initiate and dissipate the Madden–Julian Oscillation. Quart. J. Roy. Meteor. Soc., doi:10.1002/qj.2461, in press.

  • Hendon, H. H., and M. L. Salby, 1994: The life cycle of the Madden–Julian oscillation. J. Atmos. Sci., 51, 22252237, doi:10.1175/1520-0469(1994)051<2225:TLCOTM>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Hendon, H. H., and M. L. Salby, 1996: Planetary-scale circulations forced by intraseasonal variations of observed convection. J. Atmos. Sci., 53, 17511758, doi:10.1175/1520-0469(1996)053<1751:PSCFBI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Holton, J. R., 2004: Waves in the equatorial stratosphere. An Introduction to Dynamic Meteorology, F. Cynar, Ed., Elsevier Academic Press, 429–435.

  • Hoskins, B. J., and T. Ambrizzi, 1993: Rossby wave propagation on a realistic longitudinally varying flow. J. Atmos. Sci., 50, 16611671, doi:10.1175/1520-0469(1993)050<1661:RWPOAR>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kemball-Cook, S. R., and B. C. Weare, 2001: The onset of convection in the Madden–Julian oscillation. J. Climate, 14, 780793, doi:10.1175/1520-0442(2001)014<0780:TOOCIT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kerns, B. W., and S. S. Chen, 2014: Equatorial dry air intrusion and related synoptic variability in MJO initiation during DYNAMO. Mon. Wea. Rev., 142, 13261343, doi:10.1175/MWR-D-13-00159.1.

    • Search Google Scholar
    • Export Citation
  • Kessler, W. S., 2001: EOF representations of the Madden–Julian oscillation and its connection with ENSO. J. Climate, 14, 30553061, doi:10.1175/1520-0442(2001)014<3055:EROTMJ>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kikuchi, K., and Y. N. Takayabu, 2003: Equatorial circumnavigation of moisture signal associated with the Madden-Julian Oscillation (MJO) during boreal winter. J. Meteor. Soc. Japan, 81, 851869, doi:10.2151/jmsj.81.851.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., and K. M. Weickmann, 1992: Circulation anomalies associated with tropical convection during northern winter. Mon. Wea. Rev., 120, 19001923, doi:10.1175/1520-0493(1992)120<1900:CAAWTC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., K. H. Straub, G. C. Reid, and K. S. Gage, 2001: Aspects of interannual and intraseasonal variability of the tropopause and lower stratosphere. Quart. J. Roy. Meteor. Soc., 127, 19611983, doi:10.1002/qj.49712757606.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., K. H. Straub, and P. T. Haertel, 2005: Zonal and vertical structure of the Madden–Julian oscillation. J. Atmos. Sci., 62, 27902809, doi:10.1175/JAS3520.1.

    • Search Google Scholar
    • Export Citation
  • Knutson, T. R., and K. M. Weickmann, 1987: 30–60 day atmospheric oscillations: Composite life cycles of convection and circulation anomalies. Mon. Wea. Rev., 115, 14071436, doi:10.1175/1520-0493(1987)115<1407:DAOCLC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Krishnamurti, T. N., M. Kanamitsu, W. J. Koss, and J. D. Lee, 1973: Tropical east–west circulations during the northern winter. J. Atmos. Sci., 30, 780787, doi:10.1175/1520-0469(1973)030<0780:TECDTN>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Lavender, S. L., and A. J. Matthews, 2009: Response of the West African monsoon to the Madden–Julian oscillation. J. Climate, 22, 40974116, doi:10.1175/2009JCLI2773.1.

    • Search Google Scholar
    • Export Citation
  • Liebmann, B., and C. A. Smith, 1996: Description of a complete (interpolated) outgoing longwave radiation dataset. Bull. Amer. Meteor. Soc., 77, 12751277.

    • Search Google Scholar
    • Export Citation
  • Liebmann, B., G. N. Kiladis, C. S. Vera, A. C. Saulo, and L. M. V. Carvalho, 2004: Subseasonal variations of rainfall in South America in the vicinity of the low-level jet east of the Andes and comparison to those in the South Atlantic convergence zone. J. Climate, 17, 38293842, doi:10.1175/1520-0442(2004)017<3829:SVORIS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Lin, J.-L., M. Zhang, and B. Mapes, 2005: Zonal momentum budget of the Madden–Julian oscillation: The source and strength of equivalent linear damping. J. Atmos. Sci., 62, 21722188, doi:10.1175/JAS3471.1.

    • Search Google Scholar
    • Export Citation
  • Lin, J. W.-B., J. D. Neelin, and N. Zeng, 2000: Maintenance of tropical intraseasonal variability: Impact of evaporation–wind feedback and midlatitude storms. J. Atmos. Sci., 57, 27932823, doi:10.1175/1520-0469(2000)057<2793:MOTIVI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Lindzen, R. S., and T. Matsuno, 1968: On the nature of large scale wave disturbances in the equatorial lower stratosphere. J. Meteor. Soc. Japan, 46, 215220.

    • Search Google Scholar
    • Export Citation
  • Ling, J., C. Zhang, and P. Bechtold, 2013: Large-scale distinctions between MJO and non-MJO convective initiation over the tropical Indian Ocean. J. Atmos. Sci., 70, 26962712, doi:10.1175/JAS-D-13-029.1.

    • Search Google Scholar
    • Export Citation
  • Matsuno, T., 1966: Quasi-geostrophic motions in the equatorial area. J. Meteor. Soc. Japan, 44, 2543.

  • Matthews, A. J., 2000: Propagation mechanisms for the Madden-Julian Oscillation. Quart. J. Roy. Meteor. Soc., 126, 26372652, doi:10.1002/qj.49712656902.

    • Search Google Scholar
    • Export Citation
  • Matthews, A. J., 2008: Primary and successive events in the Madden–Julian Oscillation. Quart. J. Roy. Meteor. Soc., 134, 439453, doi:10.1002/qj.224.

    • Search Google Scholar
    • Export Citation
  • Matthews, A. J., and G. N. Kiladis, 1999: The tropical–extratropical interaction between high-frequency transients and the Madden–Julian oscillation. Mon. Wea. Rev., 127, 661677, doi:10.1175/1520-0493(1999)127<0661:TTEIBH>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Milliff, R. F., and R. A. Madden, 1996: The existence and vertical structure of fast, eastward-moving disturbances in the equatorial troposphere. J. Atmos. Sci., 53, 586597, doi:10.1175/1520-0469(1996)053<0586:TEAVSO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Mo, K. C., and J. N. Paegle, 2001: The Pacific–South American modes and their downstream effects. Int. J. Climatol., 21, 12111229, doi:10.1002/joc.685.

    • Search Google Scholar
    • Export Citation
  • Moore, R. W., O. Martius, and T. Spengler, 2010: The modulation of the subtropical and extratropical atmosphere in the Pacific basin in response to the Madden–Julian oscillation. Mon. Wea. Rev., 138, 27612779, doi:10.1175/2010MWR3194.1.

    • Search Google Scholar
    • Export Citation
  • Randel, W. J., and F. Wu, 2005: Kelvin wave variability near the equatorial tropopause observed in GPS radio occultation measurements. J. Geophys. Res., 110, D03102, doi:10.1029/2004JD005006.

    • Search Google Scholar
    • Export Citation
  • Ray, P., and C. Zhang, 2010: A case study of the mechanics of extratropical influence on the initiation of the Madden–Julian oscillation. J. Atmos. Sci., 67, 515528, doi:10.1175/2009JAS3059.1.

    • Search Google Scholar
    • Export Citation
  • Ray, P., and T. Li, 2013: Relative roles of circumnavigating waves and extratropics on the MJO and its relationship with the mean state. J. Atmos. Sci., 70, 876893, doi:10.1175/JAS-D-12-0153.1.

    • Search Google Scholar
    • Export Citation
  • Raymond, D. J., and Z. Fuchs, 2009: Moisture modes and the Madden–Julian oscillation. J. Climate, 22, 30313046, doi:10.1175/2008JCLI2739.1.

    • Search Google Scholar
    • Export Citation
  • Roundy, P. E., 2014: Some aspects of Western Hemisphere circulation and the Madden–Julian oscillation. J. Atmos. Sci., 71, 20272039, doi:10.1175/JAS-D-13-0210.1.

    • Search Google Scholar
    • Export Citation
  • Roundy, P. E., and W. M. Frank, 2004: Effects of low-frequency wave interactions on intraseasonal oscillations. J. Atmos. Sci., 61, 30253040, doi:10.1175/JAS-3348.1.

    • Search Google Scholar
    • Export Citation
  • Roundy, P. E., and M. A. Janiga, 2012: Analysis of vertically propagating convectively coupled equatorial waves using observations and a non-hydrostatic Boussinesq model on the equatorial beta-plane. Quart. J. Roy. Meteor. Soc., 138, 10041017, doi:10.1002/qj.983.

    • Search Google Scholar
    • Export Citation
  • Rui, H., and B. Wang, 1990: Development characteristics and dynamic structure of tropical intraseasonal convection anomalies. J. Atmos. Sci., 47, 357379, doi:10.1175/1520-0469(1990)047<0357:DCADSO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Saha, S., and Coauthors, 2010: The NCEP Climate Forecast System Reanalysis. Bull. Amer. Meteor. Soc., 91, 10151057, doi:10.1175/2010BAMS3001.1.

    • Search Google Scholar
    • Export Citation
  • Salby, M. L., and H. H. Hendon, 1994: Intraseasonal behavior of clouds, temperature, and motion in the tropics. J. Atmos. Sci., 51, 22072224, doi:10.1175/1520-0469(1994)051<2207:IBOCTA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Salby, M. L., R. R. Garcia, and H. H. Hendon, 1994: Planetary-scale circulations in the presence of climatological and wave-induced heating. J. Atmos. Sci., 51, 23442367, doi:10.1175/1520-0469(1994)051<2344:PSCITP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Seo, K.-H., and K.-Y. Kim, 2003: Propagation and initiation mechanisms of the Madden-Julian oscillation. J. Geophys. Res., 108, 4384, doi:10.1029/2002JD002876.

    • Search Google Scholar
    • Export Citation
  • Sobel, A., and D. Kim, 2012: The MJO-Kelvin wave transition. Geophys. Res. Lett., 39, L20808, doi:10.1029/2012GL053380.

  • Sobel, A., and E. Maloney, 2013: Moisture modes and the eastward propagation of the MJO. J. Atmos. Sci., 70, 187192, doi:10.1175/JAS-D-12-0189.1.

    • Search Google Scholar
    • Export Citation
  • Straub, K. H., 2013: MJO initiation in the real-time multivariate MJO index. J. Climate, 26, 11301151, doi:10.1175/JCLI-D-12-00074.1.

    • Search Google Scholar
    • Export Citation
  • Thompson, D. W. J., and D. J. Lorenz, 2004: The signature of the annular modes in the tropical troposphere. J. Climate, 17, 43304342, doi:10.1175/3193.1.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., 1991: Climate diagnostics from global analyses: Conservation of mass in ECMWF analyses. J. Climate, 4, 707722, doi:10.1175/1520-0442(1991)004<0707:CDFGAC>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Trenberth, K. E., J. W. Hurrell, and A. Solomon, 1995: Conservation of mass in three dimensions in global analyses. J. Climate, 8, 692708, doi:10.1175/1520-0442(1995)008<0692:COMITD>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Tromeur, E., and W. B. Rossow, 2010: Interaction of tropical deep convection with the large-scale circulation in the MJO. J. Climate, 23, 18371853, doi:10.1175/2009JCLI3240.1.

    • Search Google Scholar
    • Export Citation
  • Vincent, D. G., A. Fink, J. M. Schrage, and P. Speth, 1998: High- and low-frequency intraseasonal variance of OLR on annual and ENSO timescales. J. Climate, 11, 968986, doi:10.1175/1520-0442(1998)011<0968:HALFIV>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Walker, G. T., 1923: Correlation in seasonal variations of weather, VIII: A preliminary study of world weather. Mem. Indian Meteor. Dep., 24, 75131.

    • Search Google Scholar
    • Export Citation
  • Wallace, J. M., and V. E. Kousky, 1968: Observational evidence of Kelvin waves in the tropical stratosphere. J. Atmos. Sci., 25, 900907, doi:10.1175/1520-0469(1968)025<0900:OEOKWI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Weare, B. C., 2010: Madden-Julian Oscillation in the tropical stratosphere. J. Geophys. Res., 115, D17113, doi:10.1029/2009JD013748.

  • Webster, P. J., 1983: Large-scale structure of the tropical atmosphere. Large-Scale Dynamical Processes in the Atmosphere, B. J. Hoskins and R. P. Pearce, Eds., Academic Press, 235–275.

  • Webster, P. J., and J. R. Holton, 1982: Cross-equatorial response to middle-latitude forcing in a zonally varying basic state. J. Atmos. Sci., 39, 722733, doi:10.1175/1520-0469(1982)039<0722:CERTML>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Webster, P. J., and H.-R. Chang, 1988: Equatorial energy accumulation and emanation regions: Impacts of a zonally varying basic state. J. Atmos. Sci., 45, 803829, doi:10.1175/1520-0469(1988)045<0803:EEAAER>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Weickmann, K. M., G. N. Kiladis, and P. D. Sardeshmukh, 1997: The dynamics of intraseasonal atmospheric angular momentum oscillations. J. Atmos. Sci., 54, 14451461, doi:10.1175/1520-0469(1997)054<1445:TDOIAA>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wheeler, M. C., and H. H. Hendon, 2004: An all-season real-time multivariate MJO index: Development of an index for monitoring and prediction. Mon. Wea. Rev., 132, 19171932, doi:10.1175/1520-0493(2004)132<1917:AARMMI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wheeler, M. C., G. N. Kiladis, and P. J. Webster, 2000: Large-scale dynamical fields associated with convectively coupled equatorial waves. J. Atmos. Sci., 57, 613640, doi:10.1175/1520-0469(2000)057<0613:LSDFAW>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wu, Z., E. S. Sarachik, and D. S. Battisti, 2001: Thermally driven tropical circulations under Rayleigh friction and Newtonian cooling: Analytic solutions. J. Atmos. Sci., 58, 724741, doi:10.1175/1520-0469(2001)058<0724:TDTCUR>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Zhang, C., 2005: Madden-Julian Oscillation. Rev. Geophys., 43, RG2003, doi:10.1029/2004RG000158.

  • Zhao, C., T. Li, and T. Zhou, 2013: Precursor signals and processes associated with MJO initiation over the tropical Indian Ocean. J. Climate, 26, 291307, doi:10.1175/JCLI-D-12-00113.1.

    • Search Google Scholar
    • Export Citation
  • Zhou, X., and J. R. Holton, 2002: Intraseasonal variations of tropical cold-point tropopause temperatures. J. Climate, 15, 14601473, doi:10.1175/1520-0442(2002)015<1460:IVOTCP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 242 122 7
PDF Downloads 92 43 1

The Development of Upper-Tropospheric Wind over the Western Hemisphere in Association with MJO Convective Initiation

View More View Less
  • 1 Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, Albany, New York
Restricted access

Abstract

This study examines the structure and driving mechanisms of upper-tropospheric intraseasonal zonal wind anomalies over the Western Hemisphere (WH) during the convective initiation of the Madden–Julian oscillation (MJO) over the Indian Ocean using composite and budget analyses. The initiating MJO convection is more often associated with WH upper-tropospheric intraseasonal easterly wind anomalies, and when it is, it tends to develop a stronger and zonally broader envelope of enhanced convection than events associated with westerly wind anomalies. The WH upper-tropospheric zonal wind anomaly associated with the MJO is often described as a dry Kelvin wave radiated from MJO convection, but the results show that both the structure and driving mechanisms are different from the ones of theoretical Kelvin waves. Unlike the theoretical Kelvin wave, the zonal wind anomaly is not driven mainly by the zonal pressure gradient force and it is strongly coupled with rotational wind associated with subtropical and equatorward-propagating midlatitude Rossby waves. The intraseasonal zonal wind anomaly amplifies over the eastern Pacific and Atlantic basins because of advection of the background wind by intraseasonal wind in the presence of background zonal wind convergence, which allows acceleration in the same sign of the present intraseasonal zonal wind anomaly. A part of the WH intraseasonal easterly wind initiates in the lower stratosphere and is advected downward as it merges with eastward-propagating easterly wind in the upper troposphere. The initial sources of the lower-stratospheric intraseasonal easterly wind include equatorward intrusion of midlatitude waves and an equatorial Rossby wave.

Corresponding author address: Naoko Sakaeda, Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222. E-mail: nsakaeda@albany.edu

Abstract

This study examines the structure and driving mechanisms of upper-tropospheric intraseasonal zonal wind anomalies over the Western Hemisphere (WH) during the convective initiation of the Madden–Julian oscillation (MJO) over the Indian Ocean using composite and budget analyses. The initiating MJO convection is more often associated with WH upper-tropospheric intraseasonal easterly wind anomalies, and when it is, it tends to develop a stronger and zonally broader envelope of enhanced convection than events associated with westerly wind anomalies. The WH upper-tropospheric zonal wind anomaly associated with the MJO is often described as a dry Kelvin wave radiated from MJO convection, but the results show that both the structure and driving mechanisms are different from the ones of theoretical Kelvin waves. Unlike the theoretical Kelvin wave, the zonal wind anomaly is not driven mainly by the zonal pressure gradient force and it is strongly coupled with rotational wind associated with subtropical and equatorward-propagating midlatitude Rossby waves. The intraseasonal zonal wind anomaly amplifies over the eastern Pacific and Atlantic basins because of advection of the background wind by intraseasonal wind in the presence of background zonal wind convergence, which allows acceleration in the same sign of the present intraseasonal zonal wind anomaly. A part of the WH intraseasonal easterly wind initiates in the lower stratosphere and is advected downward as it merges with eastward-propagating easterly wind in the upper troposphere. The initial sources of the lower-stratospheric intraseasonal easterly wind include equatorward intrusion of midlatitude waves and an equatorial Rossby wave.

Corresponding author address: Naoko Sakaeda, Department of Atmospheric and Environmental Sciences, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222. E-mail: nsakaeda@albany.edu
Save