Trace gases measurements in convective outflow by MOZAIC: preliminary results

Johnny LuoCity College of New York, CUNY

MOZAIC: Measurements of OZone and wAter vapour by Airbus In-Service

airCraftMOZAIC FACTS:

1. 1994-present (transition to IAGOS)

2. Measuring temperature, humidity, and O3 (NOx and CO since 2000);

3. Temperature/Humidity: PT100/HUMIDCAP-H (accuracy: 0.5 K/RH 5%)

4. Ozone: Dual beam UV absorption instrument (accuracy: 2 ppb)

5. CO: Infrared CO analyzer (accuracy: 5 ppb)

6. Response time: 1 min for humidity and 30 s for CO;

7. Flight cruise levels: ~ 300-200 hPa;

Luo et al. 2011

Level of maximum outflow in the SEAC4RS region is ~10-12 km, close to the cruise level of MOZAIC flights.

RHi (%)

O3 (ppb)

CO (ppb)

Longitude

Latit

ude

India

Bay of Bengal (55 for Aug & Sep)

(197 for Aug & Sep)

Bay of Bengal Convection defined by RHi

Convection Clear

Convection Clear

Convection Clear

Clear Convection

O3 (

ppb)

O3 (

ppb)

CO (p

pb)

CO (p

pb)

Bay of Bengal Convection defined by RHi

Convection Clear

Convection Clear

Convection Clear

Clear Convection

O3 (

ppb)

O3 (

ppb)

CO (p

pb)

CO (p

pb) O3 and CO in the convective outflow

reflect their concentrations in the marine boundary layer (relatively pristine?).

Ozone sounding across the Atlantic

Kley et al. (2007)

Red: 300-275 hPaPink: 275-250 hPaYellow: 250-227 hPaGreen: 227-207 hPaBlue: <207 hPa

Tracer-tracer relationship: O3 and CO near deep convective outflow are positively correlated

Convection Clear Convection Clear

Convection Clear

Convection Clear

O3 (

ppb)

O3 (

ppb)

CO (p

pb)

CO (p

pb)

Convection defined by RHiIndia subcontinent

Convection Clear Convection Clear

Convection Clear

Convection Clear

O3 (

ppb)

O3 (

ppb)

CO (p

pb)

CO (p

pb)

India subcontinent Convection defined by RHi

Convection Clear

Convection Clear

Bay of Bengal

Tracer-tracer relationship: less correlation in the India subcontinent than Bay of Bengal

India subcontinent Bay of Bengal

Convective outflow

Convective boundary layer

Cumulus congestus (a “mysterious” cloud type in the tropics)

Johnson et al. 1999

A Flight Plan

Some science questions about cumulus congestus:

1. Why do they cease to grow? (Previous studies suggest a weak stable layer near the melting level ~ 5 km)

2. Do they moisten the middle troposphere, paving the way for deeper convection?

3. What are the characteristic vertical velocities inside the cumulus congestus?

4. Do they pump PBL trace gases just like deep convection?