Tropical Convection and MJO Shuguang Wang

Super cloud cluster on Nov 24, 2011 Convection is coupled with a range of dynamic equatorial waves and madden julian oscillations. This is illustrated in the these OLR. Which I happened to be part of it, more cloud processes. Which can be more specified shown in WK diagram. 24 Nov 2011, Meteo7 IR Tropical convection organize into large scale

Tropical convection f = 0 f = 0.5x10-4 s-1 f = 1x10-4 s-1 Liu and Montcrieff 2004 3

Large scale influence of convection ECMWF Training Course 02 May 2000 Large scale influence of convection Consider dry static energy: Qr: radiation c: condensation e: evaporation Taking spatial average over a large area, thermodynamic equation becomes : Eddy transport Large-scale vertical motion Heat effects of convection Moist Processes

Convection: large scale effects ECMWF Training Course 02 May 2000 Convection: large scale effects Thermodynamic eqn Apparent heat source Moisture eqn Apparent moisture sink Apparent momentum source Momentum eqn These are “observables” Moist Processes

Yanai et al., 1973, JAS ECMWF Training Course 02 May 2000 Moist Processes

Sounding array in tropical field programs Radiosondes are released at the “polygon” network every 3-6 hours Flux of humidity is calculated using sounding observations Based on the measurement of all the sources and sinks, the budget of moisture and energy can be constructed. Large scale vertical motion can also be derived. Large scale vertical motion Horizontal advection of moisture and temperature Sea surface temperature (SST) Surface wind speed

Sounding array observations in tropical field campaign GATE (Atlantic) TOGA-COARE (Western Pacific) DYNAMO (Indian ocean) Sounding array: Continuous sampling of atmospheric states over several months Products: areal average of budget terms for thermodynamic variables

Sounding array observation: Column modeling Precipitation fits well Obs, but other important fields may not Temperature, moisture Radiative fluxes Reflectivity, or microphysics ~64 km 22 km Dx = 1 km TOGA: Rain

Column modeling with parameterized large scale dynamics Standard method Alternative modeling strategy Large scale vertical motion Sea surface temperature (SST) Relaxation to large scale winds Horizontal advection of moisture WTG or wave coupling (WPG) Sea surface temperature (SST) Relaxation to large scale winds Free troposphere temperature Radiation Goal: Simulate cloud statistics Goal: Simulate rainfall

Two methods: WTG and Gravity-wave coupling C R M relax Θ climatology C R M Use theta’, schematic : timescale k: wavenumber ε: momentum damping at1 days Both: LS vertical motion temperature variations

Parameterizing large scale dynamics for TOGA-COARE Surface fluxes WTG Damped-wave Surface fluxes drive the responses at the given wavenumber or time scale; In fact, surface flux underestimated around day 80, while E at day 90 is similar to those at the first major MJO event, around day 50-60.

Parameterizing large-scale vertical velocity for TOGA-COARE WTG Damped-wave Now we see model results with large scale vertical velocity parameterized with two methods: WTG and Gravity-Coupling. Both methods capture the gradual ramp up during the first event, but overestimate rain during the 2nd event. Given the complexity of MJO, I contend that these results are considered to be quite good. - Rain is not specified by the large-scale forcing. Expect much less agreement. - Good agreement in rainfall for the 1st MJO event, less agreement for the 2nd MJO event

Parameterized large scale vertical velocity obs Potential Temperature: model-obs WTG WTG In WTG, vertical velocity and temperature perturbations well correlated. But not the case in Gravity-wave-coupling. This suggests the WTG is more sensitive temperature in upper troposphere. Gravity-Wave Gravity-Wave

Madden-Julian Oscillation (MJO) (Madden and Julian 1971, 1972) 30 to 90 day tropical weather cycle No satisfying theory to explain all the features Difficult for both global climate/operational models and regional models

Dynamical structure Rui and Wang (1990).

Tropical convection organize into large scale Super cloud cluster on Nov 24, 2011 Convection is coupled with a range of dynamic equatorial waves and madden julian oscillations. This is illustrated in the these OLR. Which I happened to be part of it, more cloud processes. Which can be more specified shown in WK diagram. 24 Nov 2011, Meteo7 IR This super cloud cluster is Madden-Julian Oscillation (MJO) at its initialization phase MJO: a global weather phenomenon Influence rainfall over all the tropics and subtropics

Tracking the November 2011 cloud cluster Outgoing Longwave Radiation 2.5S-2.5N Madden Julian Oscillation Kelvin wave Equatorial Rossby Wave Convection is coupled with a range of large scale dynamic processes: Madden Julian Oscillation (5 m/s eastward) Kelvin waves (13 m/s eastward) Equatorial Rossby waves (Westward propagation) Convection is coupled with a range of dynamic equatorial waves and madden julian oscillations. This is illustrated in the these OLR. Interaction between convection and large scale processes is the key. CAWCB/Bureau of Meteorology

200 hPa Velocity Potential Anomalies (10N-10S) Gottschalck et al 2013 Red dashed: eastward propagation of upper-level divergence

DYNAMO: RMM index OLR, 850/200 hPa zonal wind (Wheeler and Hendon 2004)

DYNAMO: RMM index Longitude Longitude

DYNAMO: setup of large domain WRF simulations Continuous free run for > 2 months

DYNAMO: large domain cloud-permitting WRF simulations Longitude

DYNAMO: budget of moist static energy M = cpT+gZ+LQv Oct 1

DYNAMO: Surface fluxes and radiative fluxes

Concluding remark Large scale effects of tropical convection (Q1, Q2) are observable using the sounding network Column modeling offers insights to both physics (cloud microphysics, radiation, etc.) and dynamics (parameterized large scale dynamic) Understanding coupling between convection and large scales is the key for tropical dynamics Convection is crucial for MJO, and responsible for poor simulation and prediction of MJO events in numerical models High resolution WRF modeling shows some promising results for precipitation