Matthew Shupe Ola Persson U of Colorado/NOAA Thorsten Mauritsen Max Plank Institute Ian Brooks
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Transcript of Matthew Shupe Ola Persson U of Colorado/NOAA Thorsten Mauritsen Max Plank Institute Ian Brooks
Matthew Shupe Ola Persson
U of Colorado/NOAA
Thorsten MauritsenMax Plank Institute
Ian BrooksU of Leeds
Dynamical-Microphysical Interactions in Arctic Mixed-Phase Clouds
The Arctic Summer Cloud – Ocean Study (ASCOS)Objective: Study the interactions among the atmospheric structure, clouds, aerosols, gases, ocean, and surface energy budget.
• Late summer 2008, 5 weeks for full cruise including 3 week ice station.
• Aboard Swedish icebreaker Oden
• Large suite of instruments deployed on the icebreaker, on the sea-ice, from a tethered balloon, and adjacent to an open lead.
23&31 GHzMicrowave radiometer
Ka-band Doppler Cloud Radar
449 MHzWind profiler
60 GHzRadiometer
S-band Cloud/precip Radar
Not shownCeilometer, Radiosondes
Upward-looking remote sensors
Spatial Perspective
~6 km
Measurement area
When the upper cloud leaves…..
vertical motions become more active in lower layer,
W skewness begins to show contributions from the cloud top,
in-cloud turbulence increases,
the atmospheric depth prone to vertical mixing increases in depth,
and ice production begins.
25 August Case: Multi-layer transition to single layer
25 August Case: Examining specific time periods
Upper cloud leaves and cloud starts to radiatively cool generating turbulence
Turbulent layer growth
Thermal plumes from the surface
25 August Case: Initial transition
interpolated
Turbulence near surface remains relatively constant
Shallow well-mixed layer, increases in depth over time
Peak liquid right after upper cloud goes away, with most ice later in case
Skewness decreases
In-cloud turbulence and W variance increase over time
25 August Case: ½ hour average profiles
Correlation between vertical velocity and microphysics
25 August Case:Focused view
~6 km0.7-2 km
Similar relations to those seen for stratocumulus near Barrow
25 August Case: Microphysical-dynamical relations
27-28 August Case: An example of transitionsCoupledDe-coupled De-coupled
Ice production increases with the coupling…. but doesn’t decrease after de-coupling.
Cloud top driven circulations mix down leading to coupling w/ surface
Microphysics is variable, possibly higher peak values when coupled
Thermal structure supports coupling vs. decoupling analysis
Turbulence maximized near top in “decoupled” but approximately constant w/ height for “coupled”
Skewness more negative for decoupled and more positive for coupled
interpolated
27-28 August Case: 1-hour averages
Summary and Future Directions
•Multi-instrument, remote-sensor suite can provide a coordinated perspective on cloud microphysics and dynamics.
•Dynamic and thermodynamic signatures reveal the interactions between clouds and the atmosphere (boundary layer).
Want to further understand the impact of the cloud-atmosphere state (coupled vs. uncoupled) on the dynamical and microphysical properties (scales-of-motion, phase partitioning, ice production) Expand analyses to Barrow and Eureka. Thanks!