On the height distribution of convection in the tropics
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On the Height Distribution of Convection in the Tropics. Andrew Ballinger Monash University. Introduction and Motivation. Variety of convection in the tropics Multi-modal distribution of storm heights? Johnson et al , 1999. May and Rajopadhyaya, 1999. Implications:

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Introduction and motivation
Introduction and Motivation

  • Variety of convection in the tropics

  • Multi-modal distribution of storm heights?

    • Johnson et al, 1999.

    • May and Rajopadhyaya, 1999.

  • Implications:

    • Tropospheric/Stratospheric exchange

    • Storm detrainment heights

    • Cirrus characteristics

    • Interpretation of satellite data


  • Types of convection
    Types of Convection

    Continental

    • High Z extends well above FZL

    • Active lightning

    • Strong vertical motion

    • “Break” period

      • Low-level easterlies

    Oceanic

    • High Z mostly below FZL

    • Little lightning

    • Relatively “small” vertical motion

    • “Monsoon” period

      • Low-level westerlies


    Titan
    TITAN

    Thunderstorm Identification, Tracking, Analysis, and Nowcasting.

    Reflectivity – 2km

    Reflectivity – 5km

    Reflectivity – 10km

    Reflectivity – 17km

    Dixon and Wiener, 1993





    Diurnal cycle of the number of cells 35 dbz

    2pm

    3pm

    9am

    Diurnal cycle of the number of cells (35 dBZ)

    Monsoon

    Break


    Diurnal cycle of the number of cells 45 dbz

    4pm

    7am

    2pm

    Diurnal cycle of the number of cells (45 dBZ)

    Monsoon

    Break


    Distribution of storm max heights

    Distribution of storm max heights

    10

    10

    16

    17

    14

    14

    Distribution of storm max heights

    Monsoon

    35 dBZ

    45 dBZ

    Monsoon

    Tropopause

    Break

    35 dBZ

    45 dBZ

    Break


    Break diurnal cycle of storm max heights 35 dbz
    Break – Diurnal cycle of storm max heights (35 dBZ)

    09:30 – 11:30

    15:30 – 17:30

    11:30 – 13:30

    17:30 – 19:30

    13:30 – 15:30

    19:30 – 21:30


    Summary
    Summary

    • Convective cells deeper in break compared with monsoon

    • More intense cells in break period with strong overshoots of the tropopause

    • Intense cells mostly reach tropopause

    • In the monsoon period a height distribution max is found at 10km

    • Diurnal cycle of cell heights shows build up during the day.



    References
    References

    • Dixon, M., and G. Wiener, 1993: “TITAN: Thunderstorm Identification, Tracking, Analysis, and Nowcasting – A Radar-based Methodology”, J. Atmos. Oceanic Technol., 10, 785–797.

    • Johnson, R.H., T.M. Rickenbach, S.A. Rutledge, P.E. Ciesielski and W.H. Schubert, 1999: “Trimodal Characteristics of Tropical Convection”, J. Clim., 12, 2397–2418.

    • Keenan, T.D., J. McBride, G. Holland, N. Davidson and B. Gunn, 1989: “Diurnal Variations during the Australian Monsoon Experiment (AMEX) Phase II”, Mon. Wea. Rev., 117, 2535–2552.

    • López, R.E., 1976: “Radar Characteristics of the Cloud Populations of Tropical Disturbances in the Northwest Atlantic”, Mon. Wea. Rev., 104, 268–283.


    Storm duration
    Storm Duration

    Monsoon

    Total

    Break


    Reflectivity thresholds 35
    Reflectivity Thresholds (35)

    10 dBz

    1 dBz

    15 dBz

    5 dBz


    Reflectivity thresholds 45
    Reflectivity Thresholds (45)

    10 dBz

    1 dBz

    15 dBz

    5 dBz


    Monsoon break definition
    Monsoon/Break Definition

    Monsoon

    21/12/03 – 16/1/04

    Break 17/1/04

    – 31/1/04






    Gate results
    GATE Results

    ShallowCumulus

    CongestusCumulus

    Cumulonimbus




    Outline
    Outline

    • Introduction and Motivation

    • Formulation of dataset

    • Results

    • Summary



    Acknowledgements
    Acknowledgements

    • Dr Peter May – BMRC

    • Monash University

    • Bureau of Meteorology Research Centre


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