Matthew Shupe Ola Persson Paul Johnston Duane Hazen

1. Clouds during ASCOS Matthew Shupe Ola Persson Paul Johnston Duane Hazen U. of Colorado and NOAA

2. Data sets • Millimeter Cloud Radar (MMCR) • Ka-band cloud radar • Measures Doppler spectrum, reflectivity, Doppler velocity, and spectrum width. • “Merged” product combines the best of multiple operational modes and is now available in netCDF.

3. Data sets • Ceilometer • Operates at optical wavelength. • Measures cloud base height (sometimes multiple layers) and backscatter profiles. • Product is now available in netCDF.

4. Data sets • Microwave Radiometer (MWR) • 2-channels at 23 and 31 GHz • Measures sky brightness temperatures for deriving precipitable water vapor (PWV) and cloud liquid water path (LWP). • Measurements and version#1 retrievals are available in netCDF (use retrievals with caution!)

5. Retrieved Products: Cloud type • Cloud type classification • Utilizes phase-specific signatures from radar, ceilometer, microwave radiometer, radiosondes • Provides a mask of cloud “phase” type • Version 1 available in netCDF

6. Retrieved Products: Cloud liquid properties • Liquid Retrievals • Assume “adiabatic” profile computed with active sensor cloud boundaries and temperature profile, constrained by microwave radiometer-derived LWP • Version 1 available in netCDF Liquid droplet size Liquid water content Liquid water path

7. Retrieved Products: Cloud ice properties • Ice Retrievals • Ice mass is derived using a radar reflectivity power law relationship while particle size is related to radar-measured velocity • Version 1 available in netCDF Ice particle size Ice water content Ice water path

8. Retrieved Products: Vertical velocity and turbulence • Dynamics Retrievals • Vertical velocity is derived from radar Doppler spectra using small liquid droplets as tracers of air motion • Turbulent dissipation rate is related to the time variance of radar Doppler velocity • Full data set not yet available, contact Matthew if interested in certain cases Layer-averaged vertical velocity, 5-pt smooth Vertical velocity Turbulent dissipation rate

9. Low-level stratiform cloud regime Summary Statistics Storm & deep cloud regime Lots of low clouds, most of which were “mixed-phase” (ice crystals falling from a liquid cloud layer) Liquid (red) and Ice (blue) water paths. Bars show daily range (5th-95th percentiles) and while symbol shows daily mean

10. Case Study Example 29 August 2008 Cloud Radar Moments • From the Cloud Radar Perspective • Low-level mixed-phase stratocumulus (ice falling from liquid cloud layer) • Brief mixed-phase strato/alto-cumulus • Multiple high cirrus clouds and a suggestion of possible liquid water at times.

11. Case Study Example 29 August 2008 60-GHz Potential Temperature and Buoyancy Profiles Strong inversion at about 800 m which limits the vertical cloud extent Stable layer decouples cloud from surface for first ½ of day Second ½ of day appears to be well-mixed from the surface up to the cloud at 700-800m

12. Case Study Example 29 August 2008 Retrieval Results: Multilayer Cloud Effects 1) Upper layers from 11 – 16 inhibit cloud top radiative cooling by lower layer. 2) As a result, shallow convection, turbulence, ice production, and (probably) liquid production all decrease in lower cloud layer. 3) Circulations and turbulence are significant in upper layer because it can radiatively cool to space.

13. Case Study Example 29 August 2008 • Retrieval Results: • BL-Cloud Interactions • During first ½ of day (decoupled • cloud and surface): • Relatively more ice than liquid production. • Thinner liquid layer. • Turbulence decreases towards surface. • During second ½ of day (well-mixed): • Less ice production and more liquid water • Thicker liquid layer. • Turbulence constant towards surface

14. Case Study Example 29 August 2008 1 2 3 • Examine Profiles at 3 times • Decoupled • Multi-layer • Well-mixed

15. 1) Decoupled • Turbulence profile suggests cloud top radiative cooling • Lots of ice Case Study Example 29 August 2008 • 2) Multi-layer • Upper layer turbulence shows radiative cooling • Lower layer turbulence suggests surface forcing • Less ice production in lower layer than upper Average profiles • 3) Well-mixed • Turbulence profile suggests contributions from both surface and radiative cooling

16. Case Study Example 29 August 2008 Focus on Circulations during “Well-Mixed” period Broad updrafts and narrow downdrafts on scales of 1-2 km Higher turbulence at interfaces between up- and down-drafts Cloud ice forms in updrafts No clear relationship between LWP-IWP or LWP-updraft but the LWP does increase as the liquid layer thickness increases

17. Research Interests & Potential Collaborations • Cloud interactions with boundary layer structure: • How do clouds affect the boundary layer stability (and visa versa)? • Cloud interactions with surface energy budget: • What role did cloudiness play in the end of the melt season? • Aerosol-cloud interactions, and source of particles to the cloud: • Why was there more ice production when the cloud layer was decoupled from the surface (and visa versa)? • Retrieval validation using independent measurements of vertical velocity and turbulent dissipation rate (from sodar and balloon) and cloud microphysics (from aircraft). Please contact me: matthew.shupe@noaa.gov

18. Extra slides

19. Case Study Example 29 August 2008 The Situation Low-level, stratiform mixed-phase cloud (ice falling from liquid). Short period with a second mixed-phase layer at 1.8 km Key Result 1) Shallow convection, turbulence, ice production, and (probably) liquid production all decrease in lower cloud layer. 2) Upper layer inhibits cloud top radiative cooling by lower layer, which is largely responsible for driving cloud-scale circulations.

20. Case Study Example 29 August 2008 Lots more liquid than ice Case-average profiles Cloud layers are “well mixed” Raw sounding suggests low cloud decoupled from surface Turbulent profiles