1. COSMICS Cold-air outbreak sorties
Steven Abel and Richard Cotton
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2. Cold-air outbreaks
Cold air flow over a relatively warm sea surface leading to the formation of boundary layer stratiform and convective clouds.
Model often struggles to capture these mixed phase clouds.
Similar issues occur for the southern Ocean, with the lack of cloud contributing to a large SST bias in most climate models (lots of active international research in this area).
Poor representation of mixed-phase cloud microphysics
Poor representation of surface fluxes
Unable to capture correct boundary layer structure, particularly in stratiform region.

3. Stratiform sorties B668: Stratiform clouds
GOAL: To provide measurements of the cloud topped boundary layer in the stratiform region and the transition to open cellular convection
PIKNMIX 2012: Good in-situ measurements of cloud and boundary layer structure. Model unable to capture overcast cloud in stratiform region. Well known model problem in cold-air outbreak conditions.
PIKNMIX-C: Two case-studies (similar model problems in capturing cloud)
PIKNMIX-D: No cases
COSMICS: Iceland and Kiruna operating bases to enable additional case studies.
B668: Stratiform clouds
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4. B668: PikNMix-B
The transition region and stratiform regime were well characterised by in-situ measurements.
Science on way to Iceland, refuel, return at high level dropping sondes (B668). B A
Prestwick
FL200 A B
2 km
Iceland
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5. COSMICS:
Required to operate from Iceland or Kiruna because stratiform and transition region further north. B A B
FL200 A
Norwegian Sea
Greenland Sea
2 km B C
Iceland
Keflavik
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6. Convective sorties B667:Convective clouds
GOAL: To provide comprehensive in-situ measurements of mixed-phase convective clouds in cold-air outbreak conditions for the evaluation of high resolution NWP model simulations.
CONSTRAIN / PIKNMIX 2012: Significant underestimate of IWC in the model. Good cloud microphysics data but no in-cloud dynamics (icing of turbulenece probe).
PIKNMIX-D: AIMMS-20 gives us the ability to look at in-cloud turbulence in the presence of supercooled water.
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7. Convective sorties Sortie will consist of:
Deep profiles in cloud free conditions.
Boundary layer measurements of fluxes, aerosol and precipitation A  B.
Cloud penetration runs at fixed levels. Runs generally between points A and B but deviations required to maximise number of cloud penetrations.
Points A and B orientated across mean wind direction
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8. Instrumentation Key Instruments
Temperature, Total Water, AIMMS-20, Turbulence probe, Cloud physics (all), WVSS-II, General Eastern/Buck, Nevzorov, Dropsonde
Extremely useful
FAAM CCN, FAAM CPC, GRIMM, Weather radar (for convective flights), Heimann, JW
Nice to have
ARIES, LIDAR, Core Chem, Nephelometer, PSAP, MARSS (for stratiform flight only), Aircraft video, TAMDAR
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