Precursor Signals and Processes Associated with MJO Initiation over the Tropical Indian Ocean

被引:137
|
作者
Zhao, Chongbo [1 ,2 ]
Li, Tim [3 ,4 ]
Zhou, Tianjun [1 ]
机构
[1] Chinese Acad Sci, Inst Atmospher Phys, LASG, Beijing, Peoples R China
[2] Chinese Acad Sci, Grad Univ, Beijing, Peoples R China
[3] Univ Hawaii Manoa, IPRC, Honolulu, HI 96822 USA
[4] Univ Hawaii Manoa, Dept Meteorol, Honolulu, HI 96822 USA
基金
美国国家科学基金会;
关键词
MADDEN-JULIAN OSCILLATION; SUMMER INTRASEASONAL OSCILLATION; EASTWARD PROPAGATION; VARIABILITY; MECHANISMS; CONVECTION; WIND; HEAT;
D O I
10.1175/JCLI-D-12-00113.1
中图分类号
P4 [大气科学(气象学)];
学科分类号
0706 ; 070601 ;
摘要
The precursor signals of convection initiation associated with the Madden-Julian oscillation (MJO) in boreal winter were investigated through the diagnosis of the 40-yr ECMWF Re-Analysis (ERA-40) data for the period 1982-2001. The western equatorial Indian Ocean (WIO) is a key region of the MJO initiation. A marked increase of specific humidity and temperature in the lower troposphere appears 5-10 days prior to the convection initiation. The increased moisture and temperature cause a convectively more unstable stratification, leading to the onset of convection. A diagnosis of lower-tropospheric moisture (heat) budgets shows that the moisture (temperature) increase is caused primarily by the horizontal advection of the mean specific humidity (temperature) by the MJO flow. The anomalous flow is primarily determined by the downstream Rossby wave response to a preceding suppressed-phase MJO over the eastern Indian Ocean, whereas the upstream Kelvin wave response to the previous eastward-propagating convective-phase MJO is not critical. An idealized numerical experiment further supports this claim. The Southern Hemisphere (SH) midlatitude Rossby wave train and associated wave activity flux prior to the MJO initiation were diagnosed. It is found that SH midlatitude Rossby waves may contribute to MJO initiation over the western Indian Ocean through wave energy accumulation. Idealized numerical experiments confirm that SH midlatitude perturbations play an important role in affecting the MJO variance in the tropics. A barotropic energy conversion diagnosis indicates that there is continuous energy transfer from the mean flow to intraseasonal disturbances over the initiation region, which may help trigger MJO development.
引用
收藏
页码:291 / 307
页数:17
相关论文
共 50 条
  • [41] Response of the Madden-Julian Oscillation and Tropical Atmosphere to Changes in Oceanic Mixed Layer Depth over the Indian Ocean
    Cicerone, Teresa
    Delsole, Timothy
    Trenary, Laurie
    Kirtman, Ben
    JOURNAL OF CLIMATE, 2023, 36 (12) : 4071 - 4086
  • [42] Scatterometer and reanalysis wind products over the western tropical Indian Ocean
    Collins, C.
    Reason, C. J. C.
    Hermes, J. C.
    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 2012, 117
  • [43] Evaluation of Different Heat Flux Products Over the Tropical Indian Ocean
    Pokhrel, Samir
    Dutta, Ushnanshu
    Rahaman, Hasibur
    Chaudhari, Hemantkumar
    Hazra, Anupam
    Saha, Subodh Kumar
    Veeranjaneyulu, Chinta
    EARTH AND SPACE SCIENCE, 2020, 7 (06)
  • [44] Interannual variations of tropical cyclone activity over the north Indian Ocean
    Ng, Eric K. W.
    Chan, Johnny C. L.
    INTERNATIONAL JOURNAL OF CLIMATOLOGY, 2012, 32 (06) : 819 - 830
  • [45] Summer marine heatwaves in the tropical Indian Ocean associated with an unseasonable positive Indian Ocean Dipole event 2012
    Li, Zhiyuan
    Wu, Gangfeng
    Xu, Chang
    Zhu, Xiao-Hua
    Long, Yu
    FRONTIERS IN MARINE SCIENCE, 2024, 11
  • [46] Genesis and Trends in Marine Heatwaves Over the Tropical Indian Ocean and Their Interaction With the Indian Summer Monsoon
    Saranya, J. S.
    Roxy, M. K.
    Dasgupta, Panini
    Anand, Ajay
    JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, 2022, 127 (02)
  • [47] A wave-number frequency wavelet analysis of convectively coupled equatorial waves and the MJO over the Indian Ocean
    Roundy, Paul E.
    QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, 2018, 144 (711) : 333 - 343
  • [48] Impact of upper ocean processes and air-sea fluxes on seasonal SST biases over the tropical Indian Ocean in the NCEP Climate Forecasting System
    Chowdary, Jasti S.
    Parekh, Anant
    Ojha, Sayantani
    Gnanaseelan, C.
    Kakatkar, Rashmi
    INTERNATIONAL JOURNAL OF CLIMATOLOGY, 2016, 36 (01) : 188 - 207
  • [49] Differences in the Initiation and Development of the Madden-Julian Oscillation over the Indian Ocean Associated with Two Types of El Nino
    Hsu, Pang-Chi
    Xiao, Ting
    JOURNAL OF CLIMATE, 2017, 30 (04) : 1397 - 1415
  • [50] Tropical Indian Ocean Mediates ENSO Influence Over Central Southwest Asia During the Wet Season
    Abid, Muhammad Adnan
    Ashfaq, Moetasim
    Kucharski, Fred
    Evans, Katherine J.
    Almazroui, Mansour
    GEOPHYSICAL RESEARCH LETTERS, 2020, 47 (18)