Hypothesis

Hypo. I: MJO convective envelop

only develops when the moist layer is

deep enough;

Hypo. II: Specific convective

populations at different stages are

essential for MJO initiation;

Hypo. III: The barrier layer, wind- and shear-driven mixing, shallow thermocline, and mixing-layer entrainment all play essential roles in MJO initiation.

“Discharge-Recharge”MJO onset theory

MJO Initiation and Hypothesis

Global MJO Phase (WH)

OLR&

850 mb Winds(Nov-Dec-Jan,

1974-2009)

MJO indexPhase 1-8

(Wheeler and Hendon 04)

1

2

3

4

5

6

7

8

Red box(DYNAMO)

DYNAMO MJO Definitions

Global Definition

WH 04 (RMM1, RMM2)

Local Definition

Regional Rainfall

Phase 2-3, Indian Ocean Day 0: Most active

Atmospheric Moisture Profiles—Revelle sounding data

1. Driest Atmos:

Phase 5-6

2. Lower-level

Moistening:

Phase 7-8

3. Upper-level

Moistening:

Phase 1

4. Upper Drying:

Phase 4

Overview: Environ., Precip., and Lightning

How does convective population change?Phase 1 peak lightning, peak SST, intense convection

1. In phase:

RH, Rainfall,

Strat. Rain.

Large s/f

fraction

2. In phase:

SST, Lightning,

CAPE.

Convective Feature Database (TOGA Radar)

20-dBZ radar clusters

Max Height(20, 30, 40

dBZ)

Conv./Strat.Info.

Feature SizeInfo.

LightningInfo.

Rain RateInfo.

Overall Statistics of Convective Population

DYNAMO vs. TRMM, and TOGA-COARE

MIT data?

Convective (feature) Population Small (< 200), Medium (200-1000), MCS (> 1000 km2)

Shallow (< 5 km), Middle (5-8 km), Deep (> 8 km)

“Similar Pattern in

Oct and Nov.MJO Cycle”

Horizontal Precipitating Area

Areal Mean Rain Amount

Typical Case in Phase 1 to 4

P 1 P 2

P 3 P 4

Typical Case in Phase 5 to 8

P 5-6

P 7 P 8

Daily Evolution: Convective Population

1. In phase:

RH, Rainrate,

Strat. Rain.

2. In phase:

SST, Lightning,

CAPE.

Role of Aerosols?