DYNAMO Webinar SeriesDynamics of the Madden-Julian Oscillation Field Campaign

Climate Variability & Predictability

Shipboard Measurements of Aerosol Chemical, Physical,

and Optical Properties during DYNAMO

Timothy Bates, JISAO

H. Langley DeWitt, Derek J. Coffman, Kristen S. Schulz, Patricia K. Quinn

http://saga.pmel.noaa.gov/dataWednesday, June 25, 2014 @ 2pm

Aerosols in the Indian OceanNovember AOT Average: MODIS

Aerosol measurements on the R/V Revelle: Measured the sub and supermicrometer aerosol chemical (filter-based and real-time), physical (size), and optical properties (scattering and absorption)

Clean Marine

Anthropogenically Influenced Aerosol

Aerosols in the Indian OceanNovember AOT Average: MODIS

1.How does the MJO affect aerosol properties over the Indian Ocean?

2.How could continental aerosol affect the MJO?

Tian et al., 2008

Aerosols and the MJO: Effect of Enhanced MJO Convection on Aerosols (Satellite Measurements)

TOMS Aerosol Index: measures concentration of absorbing aerosol only.

MODIS and AVHRR Aerosol Optical Thickness: measures concentration of scattering and absorbing aerosol

Negative correlation between rainfall

and aerosol concentration

anomalies(more rain: less

aerosol)

Positive correlation

between rainfall and aerosol

concentration anomalies (more

rain: more aerosol optical thickness)

Leg 2: Oct 4-Oct 30:More Marine Aerosol

Weak MJO event late October

Leg 3: Nov 8-Dec 7:More Continental Aerosol

Strong MJO event late November

Aerosol Source RegionsHYSPLIT backtrajectories

October-early December is the shoulder season after the Asian summer monsoon: wind direction over the Indian Ocean changing

from primarily southerly to primarily northerly.

7 day 200 m height aerosol back trajectories

Leg 2: Oct 1-Oct 30: Dominant marine

aerosol source, primarily acidic sulfate

Leg 3: Nov 8-Dec 7: Dominant continental aerosol source, more

ammonium sulfate, nssK+ (biomass burning tracer).

Submicron Aerosol Concentration Increased with more Continental Sources

MJO EVENT

Wind speed average of ~ 3 m/s, aerosol transport from

the Asian continent

Dominance of accumulation mode continental aerosols

Wind speed average of ~10 m/s, increased precipitation

Rainout of continental aerosols, dominance of primary marine

(e.g. sea salt) coarse-mode aerosols.

Enhanced Convection:Suppressed Convection: Increased Convection

Increase in O3 as the marine boundary layer height rises,

introduction of submicrometer particles from the FT to the MBL.

Observed Aerosol Response to the MJO: November 2011

MJO Effect on Aerosol Optical Properties: Enhances scattering, absorbing aerosols removed (active convection), suppresses

scattering, absorbing aerosols can build up (suppressed convection)

Scattering: Sea Salt, Sulfate (SSA~1)

Absorbing: Dust (0.7), Biomass Burning (0.85), Black Carbon (0.3): mostly from continental sources

Aerosol chemistry: response to the MJO:Large increase in supermicrometer sea salt aerosol and decrease in

submicrometer sulfate, organic, ammonium aerosol

Aerosol Response to the MJOSea Salt Aerosol

Continental Aerosol

Cloud Droplets

Rain Droplets

Suppressed Convection:Longer aerosol lifetime

Increased Convection:Aerosol transport from the free troposphere

Enhanced Convection:Sea-salt aerosol formed from breaking waves due to high winds

Enhanced Convection:Heavy precipitation, aerosol rainout

Suppressed Convection:Reintroduction of continental aerosols

Conclusions

• Convection associated with the MJO wave greatly affects local aerosol properties.

• More continental aerosol transport during the dry season and larger MJO anomaly signal during the dry season.– Aerosol direct and indirect effects on convection

potentially enhanced. – Is there a feedback loop between MJO convection

and aerosol?