MJO is: A convective disturbance that initiates over the tropical Indian Ocean and propagates...
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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- “Discharge- Recharge” MJO onset theory MJO Initiation and Hypothesis
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Transcript of MJO is: A convective disturbance that initiates over the tropical Indian Ocean and propagates...
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?
