• Dias, J., , and G. N. Kiladis, 2014: Influence of the basic state zonal flow on convectively coupled equatorial waves. Geophys. Res. Lett., 41, 69046913, doi:10.1002/2014GL061476.

    • Search Google Scholar
    • Export Citation
  • Dias, J., , S. N. Tulich, , and G. N. Kiladis, 2012: An object-based approach to assessing tropical convection organization. J. Atmos. Sci., 69, 24882504, doi:10.1175/JAS-D-11-0293.1

    • Search Google Scholar
    • Export Citation
  • Frank, W. M., , and P. E. Roundy, 2006: The role of tropical waves in tropical cyclogenesis. Mon. Wea. Rev., 134, 23972417, doi:10.1175/MWR3204.1

    • Search Google Scholar
    • Export Citation
  • Frierson, D. M. W., , D. Kim, , I.-S. Kang, , M.-I. Lee, , and J. Lin, 2011: Structure of AGCM-simulated convectively coupled Kelvin waves and sensitivity to convective parameterization. J. Atmos. Sci., 68, 2645, doi:10.1175/2010JAS3356.1

    • Search Google Scholar
    • Export Citation
  • Funatsu, B. M., , and D. W. Waugh, 2008: Connections between potential vorticity intrusions and convection in the eastern tropical Pacific. J. Atmos. Sci., 65, 9871002, doi:10.1175/2007JAS2248.1.

    • Search Google Scholar
    • Export Citation
  • Gloeckler, L. C., , and P. E. Roundy, 2013: Modulation of the extratropical circulation by combined activity of the Madden–Julian oscillation and equatorial Rossby waves during boreal winter. Mon. Wea. Rev., 141, 13471357, doi:10.1175/MWR-D-12-00179.1.

    • Search Google Scholar
    • Export Citation
  • Goswami, P., , and B. N. Goswami, 1991: Modification of n = 0 equatorial waves due to interaction between convection and dynamics. J. Atmos. Sci., 48, 22312244, doi:10.1175/1520-0469(1991)048〈2231:MOEWDT〉2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Han, Y., , and B. Khouider, 2010: Convectively coupled waves in a sheared environment. J. Atmos. Sci., 67, 29132942, doi:10.1175/2010JAS3335.1.

    • Search Google Scholar
    • Export Citation
  • Hayashi, Y., 1976: Non-singular resonance of equatorial waves under the radiation condition. J. Atmos. Sci., 33, 183201, doi:10.1175/1520-0469(1976)033〈0183:NSROEW〉2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Hendon, H. H., , and B. Liebmann, 1991: The structure and annual variation of antisymmetric fluctuations of tropical convection and their association with Rossby–gravity waves. J. Atmos. Sci., 48, 21272140, doi:10.1175/1520-0469(1991)048<2127:TSAAVO>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Hung, M.-P., , J.-L. Lin, , W. Wang, , D. Kim, , T. Shinoda, , and S. J. Weaver, 2013: MJO and convectively coupled equatorial waves simulated by CMIP5 climate models. J. Climate, 26, 61856214, doi:10.1175/JCLI-D-12-00541.1.

    • Search Google Scholar
    • Export Citation
  • Itoh, H., , and M. Ghil, 1988: The generation mechanism of mixed Rossby–gravity waves in the equatorial troposphere. J. Atmos. Sci., 45, 585604, doi:10.1175/1520-0469(1988)045〈0585:TGMOMR〉2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., 1998: Observations of Rossby waves linked to convection over the eastern tropical Pacific. J. Atmos. Sci., 55, 321339, doi:10.1175/1520-0469(1998)055〈0321:OORWLT〉2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., , M. C. Wheeler, , P. T. Haertel, , K. H. Straub, , and P. E. Roundy, 2009: Convectively coupled equatorial waves. Rev. Geophys., 47, 374399, doi:10.1175/1520-0469(1999)056<0374:CCEWAO>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Kiladis, G. N., , J. Dias, , and M. Gehne, 2016: The relationship between equatorial mixed Rossby–gravity and eastward inertio-gravity waves. Part I. J. Atmos. Sci., 73, 21232145, doi:10.1175/JAS-D-15-0230.1.

    • Search Google Scholar
    • Export Citation
  • Lamb, V. R., 1973: The response of a tropical atmosphere to middle latitude forcing. Ph.D. thesis, University of California, Los Angeles, 151 pp.

  • Liebmann, B., , and H. H. Hendon, 1990: Synoptic-scale disturbances near the equator. J. Atmos. Sci., 47, 14631479, doi:10.1175/1520-0469(1990)047<1463:SSDNTE>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Lin, J. L., , M. I. Lee, , D. Kim, , I. S. Kang, , and D. M. W. Frierson, 2008: The impacts of convective parameterization and moisture triggering on AGCM-simulated convectively coupled equatorial waves. J. Climate, 21, 883909, doi:10.1175/2007JCLI1790.1.

    • Search Google Scholar
    • Export Citation
  • Magaña, V., , and M. Yanai, 1995: Mixed Rossby–gravity waves triggered by lateral forcing. J. Atmos. Sci., 52, 14731486, doi:10.1175/1520-0469(1995)052<1473:MRWTBL>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Mak, M.-K., 1969: Laterally driven stochastic motions in the tropics. J. Atmos. Sci., 26, 4164, doi:10.1175/1520-0469(1969)026<0041:LDSMIT>2.0.CO;2

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

  • Monteiro, J. M., , A. F. Adams, , J. M. Wallace, , and J. S. Sukhatme, 2014: Interpreting the upper level structure of the Madden–Julian oscillation. Geophys. Res. Lett., 41, 91589165, doi:10.1002/2014GL062518.

    • Search Google Scholar
    • Export Citation
  • North, G. R., , T. L. Bell, , R. F. Cahalan, , and F. J. Moeng, 1982: Sampling errors in the estimation of empirical orthogonal functions. Mon. Wea. Rev., 110, 699706, doi:10.1175/1520-0493(1982)110<0699:SEITEO>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Raupp, C. F. M., , and P. L. Silva Dias, 2005: Excitation mechanism of mixed Rossby–gravity waves in the equatorial atmosphere: Role of the nonlinear interactions among equatorial waves. J. Atmos. Sci., 62, 14461462, doi:10.1175/JAS3412.1

    • Search Google Scholar
    • Export Citation
  • Schreck, C. J., , J. Molinari, , and K. I. Mohr, 2011: Attributing tropical cyclogenesis to equatorial waves in the western north Pacific. J. Atmos. Sci., 68, 195209, doi:10.1175/2010JAS3396.1

    • Search Google Scholar
    • Export Citation
  • Silva Dias, P. L., , W. H. Schubert, , and M. DeMaria, 1983: Large-scale response of the tropical atmosphere to transient convection. J. Atmos. Sci., 40, 26892707, doi:10.1175/1520-0469(1983)040<2689:LSROTT>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Straub, K. H., , P. T. Haertel, , and G. N. Kiladis, 2010: An analysis of convectively coupled Kelvin waves in 20 WCRP CMIP3 global coupled climate models. J. Climate, 23, 30313056, doi:10.1175/2009JCLI3422.1

    • Search Google Scholar
    • Export Citation
  • Torrence, C., , and G. P. Compo, 1998: A practical guide to wavelet analysis. Bull. Amer. Meteor. Soc., 79, 6178, doi:10.1175/1520-0477(1998)079<0061:APGTWA>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Wallace, J. M., , and C. P. Chang, 1969: Spectrum analysis of large-scale wave disturbances in the tropical lower troposphere. J. Atmos. Sci., 26, 10101025, doi:10.1175/1520-0469(1969)026<1010:SAOLSW>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Wang, B., , and X. Xie, 1996: Low-frequency equatorial waves in vertically sheared zonal flow. Part I: Stable waves. J. Atmos. Sci., 53, 34243437, doi:10.1175/1520-0469(1996)053<0449:LFEWIV>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Wheeler, M. C., , and G. N. Kiladis, 1999: Convectively coupled equatorial waves: Analysis of clouds and temperature in the wavenumber–frequency domain. J. Atmos. Sci., 56, 374399, doi:10.1175/1520-0469(1999)056<0374:CCEWAO>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
  • Wilson, J. D., , and M. Mak, 1984: Tropical response to lateral forcing with a latitudinally and zonally nonuniform basic state. J. Atmos. Sci., 41, 11871201, doi:10.1175/1520-0469(1984)041<1187:TRTLFW>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Xie, X., , and B. Wang, 1996: Low-frequency equatorial waves in vertically sheared zonal flow. Part II: Unstable waves. J. Atmos. Sci., 53, 35893605, doi:10.1175/1520-0469(1996)053<3589:LFEWIV>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Yanai, M., , and M.-M. Lu, 1983: Equatorially trapped waves at the 200 mb level and their association with meridional convergence of wave energy flux. J. Atmos. Sci., 40, 27852803, doi:10.1175/1520-0469(1983)040<2785:ETWATM>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Yanai, M., , T. Maruyama, , T. Nitta, , and Y. Hayashi, 1968: Power spectra of large-scale disturbances over the tropical Pacific. J. Meteor. Soc. Japan, 46, 291294.

    • Search Google Scholar
    • Export Citation
  • Zangvil, A., , and M. Yanai, 1980: Upper tropospheric waves in the tropics. Part I: Dynamical analysis in the wavenumber-frequency domain. J. Atmos. Sci., 37, 283298, doi:10.1175/1520-0469(1980)037<0283:UTWITT>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Zhang, C., 1993: Laterally forced equatorial perturbations in a linear model. Part II: Mobile forcing. J. Atmos. Sci., 50, 807821, doi:10.1175/1520-0469(1993)050<0807:LFEPIA>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Zhang, C., , and P. J. Webster, 1989: Effects of zonal flows on equatorially trapped waves. J. Atmos. Sci., 46, 36323652, doi:10.1175/1520-0469(1989)046<3632:EOZFOE>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Zhang, C., , and P. J. Webster, 1992: Laterally forced equatorial perturbations in a linear model. Part I: Stationary transient forcing. J. Atmos. Sci., 49, 585607, doi:10.1175/1520-0469(1992)049<0585:LFEPIA>2.0.CO;2

    • Search Google Scholar
    • Export Citation
  • Zhou, L., , and I.-S. Kang, 2013: Influence of convective momentum transport on mixed Rossby–gravity waves: A contribution to tropical 2-day waves. J. Atmos. Sci., 70, 24672475, doi:10.1175/JAS-D-12-0300.1

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 36 36 11
PDF Downloads 29 29 13

The Relationship between Equatorial Mixed Rossby–Gravity and Eastward Inertio-Gravity Waves. Part II

View More View Less
  • 1 CIRES, University of Colorado, and NOAA/Earth System Research Laboratory, Boulder, Colorado
  • 2 Physical Sciences Division, NOAA/Earth System Research Laboratory, Boulder, Colorado
© Get Permissions
Restricted access

Abstract

Space–time spectral analysis of tropical cloudiness data shows strong evidence that convectively coupled n = 0 mixed Rossby–gravity waves (MRGs) and eastward inertio-gravity waves (EIGs) occur primarily within the western/central Pacific Ocean. Spectral filtering also shows that MRG and EIG cloudiness patterns are antisymmetric with respect to the equator, and they propagate coherently toward the west and east, respectively, with periods between 3 and 5 days, in agreement with Matsuno’s linear shallow-water theory. In contrast to the spectral approach, in a companion paper it has been shown that empirical orthogonal functions (EOFs) of 2–6-day-filtered cloudiness data within the tropical Pacific Ocean also suggest an antisymmetric pattern, but with the leading EOFs implying a zonally standing but poleward-propagating oscillation, along with the associated tropospheric flow moving to the west. In the present paper, these two views are reconciled by applying an independent approach based on a tracking method to assess tropical convection organization. It is shown that, on average, two-thirds of MRG and EIG events develop independently of one another, and one-third of the events overlap in space and time. This analysis also verifies that MRG and EIG cloudiness fields tend to propagate meridionally away from the equator. It is demonstrated that the lack of zonal propagation implied from the EOF analysis is likely due to the interference between eastward- and westward-propagating disturbances. In addition, it is shown that the westward-propagating circulation associated with the leading EOF is consistent with the expected theoretical behavior of an interference between MRGs and EIGs.

Corresponding author address: Juliana Dias, Physical Sciences Division, NOAA/ESRL, R/PSD1, 325 Broadway, Boulder, CO 80305. E-mail: juliana.dias@noaa.gov

Abstract

Space–time spectral analysis of tropical cloudiness data shows strong evidence that convectively coupled n = 0 mixed Rossby–gravity waves (MRGs) and eastward inertio-gravity waves (EIGs) occur primarily within the western/central Pacific Ocean. Spectral filtering also shows that MRG and EIG cloudiness patterns are antisymmetric with respect to the equator, and they propagate coherently toward the west and east, respectively, with periods between 3 and 5 days, in agreement with Matsuno’s linear shallow-water theory. In contrast to the spectral approach, in a companion paper it has been shown that empirical orthogonal functions (EOFs) of 2–6-day-filtered cloudiness data within the tropical Pacific Ocean also suggest an antisymmetric pattern, but with the leading EOFs implying a zonally standing but poleward-propagating oscillation, along with the associated tropospheric flow moving to the west. In the present paper, these two views are reconciled by applying an independent approach based on a tracking method to assess tropical convection organization. It is shown that, on average, two-thirds of MRG and EIG events develop independently of one another, and one-third of the events overlap in space and time. This analysis also verifies that MRG and EIG cloudiness fields tend to propagate meridionally away from the equator. It is demonstrated that the lack of zonal propagation implied from the EOF analysis is likely due to the interference between eastward- and westward-propagating disturbances. In addition, it is shown that the westward-propagating circulation associated with the leading EOF is consistent with the expected theoretical behavior of an interference between MRGs and EIGs.

Corresponding author address: Juliana Dias, Physical Sciences Division, NOAA/ESRL, R/PSD1, 325 Broadway, Boulder, CO 80305. E-mail: juliana.dias@noaa.gov
Save