trace gases measurements in convective outflow by mozaic: preliminary results johnny luo city...
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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?