• Adames, Á. F., and D. Kim, 2016: The MJO as a dispersive, convectively coupled moisture wave: Theory and observations. J. Atmos. Sci., 73, 913941, https://doi.org/10.1175/JAS-D-15-0170.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, G., and B. Wang, 2019: Dynamic moisture mode versus moisture mode in MJO dynamics: Importance of the wave feedback and boundary layer convergence feedback. Climate Dyn., 52, 51275143, https://doi.org/10.1007/s00382-018-4433-7.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, G., and B. Wang, 2020: Circulation factors determining the propagation speed of the Madden–Julian oscillation. J. Climate, 33, 33673380, https://doi.org/10.1175/JCLI-D-19-0661.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Chen, X., J. Ling, and C. Li, 2016: Evolution of the Madden–Julian oscillation in two types of El Niño. J. Climate, 29, 19191934, https://doi.org/10.1175/JCLI-D-15-0486.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Deng, L., T. Li, J. Liu, and M. Peng, 2016: Factors controlling the interannual variations of MJO intensity. J. Meteor. Res., 30, 328340, https://doi.org/10.1007/s13351-016-5113-3.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Emanuel, K. A., 1987: An air–sea interaction model of intraseasonal oscillations in the tropics. J. Atmos. Sci., 44, 23242340, https://doi.org/10.1175/1520-0469(1987)044<2324:AASIMO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Everitt, B. S., S. Landau, M. Leese, and D. Stahl, 2011: Cluster Analysis. Wiley, 346 pp.

    • Crossref
    • Export Citation
  • Feng, J., T. Li, and W. Zhu, 2015a: Propagating and nonpropagating MJO events over the Maritime Continent. J. Climate, 28, 84308449, https://doi.org/10.1175/JCLI-D-15-0085.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Feng, J., P. Liu, W. Chen, and X. Wang, 2015b: Contrasting Madden–Julian oscillation activity during various stages of EP and CP El Niños. Atmos. Sci. Lett., 16, 3237, https://doi.org/10.1002/asl2.516.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fink, A., and P. Speth, 1997: Some potential forcing mechanisms of the year-to-year variability of the tropical convection and its intraseasonal (25–70-day) variability. Int. J. Climatol., 17, 15131534, https://doi.org/10.1002/(SICI)1097-0088(19971130)17:14<1513::AID-JOC210>3.0.CO;2-U.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fuchs, Ž., and D. J. Raymond, 2017: A simple model of intraseasonal oscillations. J. Adv. Model. Earth Syst., 9, 11951211, https://doi.org/10.1002/2017MS000963..

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Fuchs-Stone, Ž., 2020: WISHE-moisture mode in a vertically resolved model. J. Adv. Model. Earth Syst., 12, e2019MS001839, https://doi.org/10.1029/2019MS001839.

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

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gutzler, D. S., 1991: Interannual fluctuations of intraseasonal variance of near-equatorial zonal winds. J. Geophys. Res. Oceans, 96, 31733185, https://doi.org/10.1029/90JD01831.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Gutzler, D. S., and R. A. Madden, 1989: Seasonal variations in the spatial structure of intraseasonal tropical wind fluctuations. J. Atmos. Sci., 46, 641660, https://doi.org/10.1175/1520-0469(1989)046<0641:SVITSS>2.0.CO;2.

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

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hendon, H. H., C. Zhang, and J. D. Glick, 1999: Interannual variation of the Madden–Julian oscillation during austral summer. J. Climate, 12, 25382550, https://doi.org/10.1175/1520-0442(1999)012<2538:IVOTMJ>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hersbach, H., and et al. , 2020: The ERA5 global reanalysis. Quart. J. Roy. Meteor. Soc., 146, 19992049, https://doi.org/10.1002/qj.3803.

  • Hsu, P., and T. Li, 2012: Role of the boundary layer moisture asymmetry in causing the eastward propagation of the Madden–Julian oscillation. J. Climate, 25, 49144931, https://doi.org/10.1175/JCLI-D-11-00310.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hu, F., T. Li, J. Gao, and L. Hao, 2021: Reexamining the moisture mode theories of the Madden–Julian oscillation based on observational analyses. J. Climate, 34, 839853, https://doi.org/10.1175/JCLI-D-20-0441.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hu, Q., and D. A. Randall, 1994: Low-frequency oscillations in radiative-convective systems. J. Atmos. Sci., 51, 10891099, https://doi.org/10.1175/1520-0469(1994)051<1089:LFOIRC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Hu, Q., and D. A. Randall, 1995: Low-frequency oscillations in radiative-convective systems. Part II: An idealized model. J. Atmos. Sci., 52, 478490, https://doi.org/10.1175/1520-0469(1995)052<0478:LFOIRC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Inness, P. M., and J. M. Slingo, 2003: Simulation of the Madden–Julian oscillation in a coupled general circulation model. Part I: Comparison with observations and an atmosphere-only GCM. J. Climate, 16, 345364, https://doi.org/10.1175/1520-0442(2003)016<0345:SOTMJO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Izumo, T., and et al. , 2010: Low and high frequency Madden–Julian oscillations in austral summer: Interannual variations. Climate Dyn., 35, 669683, https://doi.org/10.1007/s00382-009-0655-z.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kaufman, L., and P. J. Rousseeuw, 2005: Finding Groups in Data: An Introduction to Cluster Analysis. Wiley, 342 pp.

  • Kiladis, G. N., and et al. , 2014: A comparison of OLR and circulation-based indices for tracking the MJO. Mon. Wea. Rev., 142, 16971715, https://doi.org/10.1175/MWR-D-13-00301.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kim, D., J. Kug, and A. H. Sobel, 2014: Propagating versus nonpropagating Madden–Julian oscillation events. J. Climate, 27, 111125, https://doi.org/10.1175/JCLI-D-13-00084.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kim, D., H. Kim, and M. I. Lee, 2017: Why does the MJO detour the Maritime Continent during austral summer? Geophys. Res. Lett., 44, 25792587, https://doi.org/10.1002/2017GL072643.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Kim, H., F. Vitart, and D. E. Waliser, 2018: Prediction of the Madden–Julian oscillation: A review. J. Climate, 31, 94259443, https://doi.org/10.1175/JCLI-D-18-0210.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Lau, K. M., and P. H. Chan, 1986: The 40–50 day oscillation and the El Niño/Southern oscillation: A new perspective. Bull. Amer. Meteor. Soc., 67, 533534, https://doi.org/10.1175/1520-0477(1986)067<0533:TDOATE>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, T., 2014: Recent advance in understanding the dynamics of the Madden–Julian oscillation. J. Meteor. Res., 28 (1), 133, https://doi.org/10.1007/s13351-014-3087-6.

    • Search Google Scholar
    • Export Citation
  • Li, T., and F. Hu, 2019: A coupled moisture-dynamics model of the Madden–Julian oscillation: Convection interaction with first and second baroclinic modes and planetary boundary layer. Climate Dyn., 53, 55295546, https://doi.org/10.1007/s00382-019-04879-x.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, T., C. Zhao, P. Hsu, and T. Nasuno, 2015: MJO initiation processes over the tropical Indian Ocean during DYNAMO/CINDY2011. J. Climate, 28, 21212135, https://doi.org/10.1175/JCLI-D-14-00328.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, T., and et al. , 2018: A paper on the tropical intraseasonal oscillation published in 1963 in a Chinese journal. Bull. Amer. Meteor. Soc., 99, 17651779, https://doi.org/10.1175/BAMS-D-17-0216.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Li, T., J. Ling, and P. Hsu, 2020: Madden–Julian oscillation: Its discovery, dynamics, and impact on East Asia. J. Meteor. Res., 34, 2042, https://doi.org/10.1007/s13351-020-9153-3.

    • Crossref
    • 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, https://doi.org/10.1175/1520-0477-77.6.1274.

    • Search Google Scholar
    • Export Citation
  • Lin, J., B. Mapes, M. Zhang, and M. Newman, 2004: Stratiform precipitation, vertical heating profiles, and the Madden–Julian oscillation. J. Atmos. Sci., 61, 296309, https://doi.org/10.1175/1520-0469(2004)061<0296:SPVHPA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Madden, R. A., and P. R. Julian, 1971: Detection of a 40–50 day oscillation in the zonal wind in the tropical Pacific. J. Atmos. Sci., 28, 702708, https://doi.org/10.1175/1520-0469(1971)028<0702:DOADOI>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Madden, R. A., and P. R. Julian, 1972: Description of global-scale circulation cells in the tropics with a 40–50 day period. J. Atmos. Sci., 29, 11091123, https://doi.org/10.1175/1520-0469(1972)029<1109:DOGSCC>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Madden, R. A., and P. R. Julian, 1994: Observations of the 40–50-day tropical oscillation—A review. Mon. Wea. Rev., 122, 814837, https://doi.org/10.1175/1520-0493(1994)122<0814:OOTDTO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Maloney, E. D., 2009: The moist static energy budget of a composite tropical intraseasonal oscillation in a climate model. J. Climate, 22, 711729, https://doi.org/10.1175/2008JCLI2542.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Neelin, J. D., and I. M. Held, 1987: Modeling tropical convergence based on the moist static energy budget. Mon. Wea. Rev., 115, 312, https://doi.org/10.1175/1520-0493(1987)115<0003:MTCBOT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Pohl, B., and A. J. Matthews, 2007: Observed changes in the lifetime and amplitude of the Madden–Julian oscillation associated with interannual ENSO sea surface temperature anomalies. J. Climate, 20, 26592674, https://doi.org/10.1175/JCLI4230.1.

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

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., T. M. Smith, C. Liu, D. B. Chelton, K. S. Casey, and M. G. Schlax, 2007: Daily high-resolution-blended analyses for sea surface temperature. J. Climate, 20, 54735496, https://doi.org/10.1175/2007JCLI1824.1.

    • Crossref
    • 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, https://doi.org/10.1175/1520-0469(1990)047<0357:DCADSO>2.0.CO;2.

    • Crossref
    • 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, https://doi.org/10.1175/1520-0469(1994)051<2207:IBOCTA>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sobel, A., and E. Maloney, 2013: Moisture modes and the eastward propagation of the MJO. J. Atmos. Sci., 70, 187192, https://doi.org/10.1175/JAS-D-12-0189.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sperber, K. R., 2003: Propagation and the vertical structure of the Madden–Julian oscillation. Mon. Wea. Rev., 131, 30183037, https://doi.org/10.1175/1520-0493(2003)131<3018:PATVSO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Suematsu, T., and H. Miura, 2018: Zonal SST difference as a potential environmental factor supporting the longevity of the Madden–Julian oscillation. J. Climate, 31, 75497564, https://doi.org/10.1175/JCLI-D-17-0822.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Tam, C., and N. Lau, 2005: Modulation of the Madden–Julian oscillation by ENSO: Inferences from observations and GCM simulations. J. Meteor. Soc. Japan, 83, 727743, https://doi.org/10.2151/jmsj.83.727.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Vitart, F., and et al. , 2017: The subseasonal to seasonal (S2S) prediction project database. Bull. Amer. Meteor. Soc., 98, 163173, https://doi.org/10.1175/BAMS-D-16-0017.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, B., 1988: Comments on “An air–sea interaction model of intraseasonal oscillation in the tropics.” J. Atmos. Sci., 45, 35213525, https://doi.org/10.1175/1520-0469(1988)045<3521:COAIMO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, B., and H. Rui, 1990: Synoptic climatology of transient tropical intraseasonal convection anomalies: 1975–1985. Meteor. Atmos. Phys., 44, 4361, https://doi.org/10.1007/BF01026810.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, B., and T. Li, 1994: Convective interaction with boundary-layer dynamics in the development of a tropical intraseasonal system. J. Atmos. Sci., 51, 13861400, https://doi.org/10.1175/1520-0469(1994)051<1386:CIWBLD>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, B., G. Chen, and F. Liu, 2019: Diversity of the Madden–Julian oscillation. Sci. Adv., 5, eaax0220, https://doi.org/10.1126/sciadv.aax0220.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, L., and T. Li, 2020: Reexamining the MJO moisture mode theories with normalized phase evolutions. J. Climate, 33, 85238536, https://doi.org/10.1175/JCLI-D-20-0202.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, L., T. Li, E. Maloney, and B. Wang, 2017: Fundamental causes of propagating and nonpropagating MJOs in MJOTF/GASS models. J. Climate, 30, 37433769, https://doi.org/10.1175/JCLI-D-16-0765.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, L., T. Li, L. Chen, S. K. Behera, and T. Nasuno, 2018: Modulation of the MJO intensity over the equatorial western Pacific by two types of El Niño. Climate Dyn., 51, 687700, https://doi.org/10.1007/s00382-017-3949-6.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, T., and T. Li, 2020: Diagnosing the column-integrated moist static energy budget associated with the northward-propagating boreal summer intraseasonal oscillation. Climate Dyn., 54, 47114732, https://doi.org/10.1007/s00382-020-05249-8.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, T., X. Yang, J. Fang, X. Sun, and X. Ren, 2018: Role of air–sea interaction in the 30–60-day boreal summer intraseasonal oscillation over the western North Pacific. J. Climate, 31, 16531680, https://doi.org/10.1175/JCLI-D-17-0109.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wang, T., C. Chu, X. Sun, and T. Li, 2020: Improving real-time forecast of intraseasonal variabilities of Indian summer monsoon precipitation in an empirical scheme. Front. Earth Sci., 8, 577311, https://doi.org/10.3389/feart.2020.577311.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Ward, J. H., 1963: Hierarchical grouping to optimize an objective function. J. Amer. Stat. Assoc., 58, 236244, https://doi.org/10.1080/01621459.1963.10500845.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wei, Y., and H. Ren, 2019: Modulation of ENSO on fast and slow MJO modes during boreal winter. J. Climate, 32, 74837506, https://doi.org/10.1175/JCLI-D-19-0013.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wheeler, M., and G. N. Kiladis, 1999: Convectively coupled equatorial waves: Analysis of clouds and temperature in the wavenumber–frequency domain. J. Atmos. Sci., 56, 374399, https://doi.org/10.1175/1520-0469(1999)056<0374:CCEWAO>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Wierzchon, S., and M. Klopotek, 2018: Modern Algorithms of Cluster Analysis. Springer, 421 pp.

    • Crossref
    • Export Citation
  • Xie, Y., S. Chen, Y. Zhang, and Y. Huang, 1963: A preliminarily statistic and synoptic study about the basic currents over southeastern Asia and the initiation of typhoon (in Chinese). Acta Meteor. Sin., 33, 206217.

    • Search Google Scholar
    • Export Citation
  • Yanai, M., S. Esbensen, and J. Chu, 1973: Determination of bulk properties of tropical cloud clusters from large-scale heat and moisture budgets. J. Atmos. Sci., 30, 611627, https://doi.org/10.1175/1520-0469(1973)030<0611:DOBPOT>2.0.CO;2.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, C., 2005: Madden–Julian oscillation. Rev. Geophys., 43, RG2003, https://doi.org/10.1029/2004RG000158.

  • Zhang, C., 2013: Madden–Julian oscillation: Bridging weather and climate. Bull. Amer. Meteor. Soc., 94, 18491870, https://doi.org/10.1175/BAMS-D-12-00026.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Zhang, C., and J. Ling, 2017: Barrier effect of the Indo-Pacific Maritime Continent on the MJO: Perspectives from tracking MJO precipitation. J. Climate, 30, 34393459, https://doi.org/10.1175/JCLI-D-16-0614.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 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, https://doi.org/10.1175/JCLI-D-12-00113.1.

    • Crossref
    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 194 194 32
Full Text Views 85 85 9
PDF Downloads 109 109 9

Factors Controlling the Diversities of MJO Propagation and Intensity

View More View Less
  • 1 a Key Laboratory of Meteorological Disaster, Ministry of Education, Joint International Research Laboratory of Climate and Environmental Change, Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing, China
  • | 2 b International Pacific Research Center and Department of Atmospheric Sciences, School of Ocean and Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, Hawaii
© Get Permissions Rent on DeepDyve
Restricted access

Abstract

The diversity of the Madden–Julian oscillation (MJO) in terms of its maximum intensity, zonal extent, and phase speed was explored using a cluster analysis method. The zonal extent is found to be significantly correlated to the phase speed. A longer zonal extent is often associated with a faster phase speed. The diversities of zonal extent and speed are connected with distinctive interannual sea surface temperature anomaly (SSTA) distributions and associated moisture and circulation patterns over the equatorial Pacific. An El Niño–like background SSTA leads to enhanced precipitation over the central Pacific, allowing a stronger vertically overturning circulation to the east of the MJO. This promotes both a larger east–west asymmetry of column-integrated moist static energy (MSE) tendency and a greater boundary layer moisture leading, serving as potential causes of the faster phase speed. The El Niño–like SSTA also favors the MJOs intruding farther into the Pacific, causing a larger zonal extent. The intensity diversity is associated with the interannual SSTA over the Maritime Continent and background moisture condition over the tropical Indian Ocean. An observed warm SSTA over the Maritime Continent excites a local Walker cell with a subsidence over the Indian Ocean, which could decrease the background moisture, weakening the MJO intensity. The intensity difference between strong and weak events would be amplified due to distinct intensity growth speed. The faster intensity growth of a strong MJO is attributed to a greater longwave radiative heating and a greater surface latent heat flux, both of which contribute to a greater total time change rate of the column-integrated MSE.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Tim Li, timli@hawaii.edu

Abstract

The diversity of the Madden–Julian oscillation (MJO) in terms of its maximum intensity, zonal extent, and phase speed was explored using a cluster analysis method. The zonal extent is found to be significantly correlated to the phase speed. A longer zonal extent is often associated with a faster phase speed. The diversities of zonal extent and speed are connected with distinctive interannual sea surface temperature anomaly (SSTA) distributions and associated moisture and circulation patterns over the equatorial Pacific. An El Niño–like background SSTA leads to enhanced precipitation over the central Pacific, allowing a stronger vertically overturning circulation to the east of the MJO. This promotes both a larger east–west asymmetry of column-integrated moist static energy (MSE) tendency and a greater boundary layer moisture leading, serving as potential causes of the faster phase speed. The El Niño–like SSTA also favors the MJOs intruding farther into the Pacific, causing a larger zonal extent. The intensity diversity is associated with the interannual SSTA over the Maritime Continent and background moisture condition over the tropical Indian Ocean. An observed warm SSTA over the Maritime Continent excites a local Walker cell with a subsidence over the Indian Ocean, which could decrease the background moisture, weakening the MJO intensity. The intensity difference between strong and weak events would be amplified due to distinct intensity growth speed. The faster intensity growth of a strong MJO is attributed to a greater longwave radiative heating and a greater surface latent heat flux, both of which contribute to a greater total time change rate of the column-integrated MSE.

© 2021 American Meteorological Society. For information regarding reuse of this content and general copyright information, consult the AMS Copyright Policy (www.ametsoc.org/PUBSReuseLicenses).

Corresponding author: Tim Li, timli@hawaii.edu
Save