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

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.

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

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!)

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

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

Retrieved Products: Cloud ice properties Ice particle size Ice water content Ice water path 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

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 Retrieved Products: Vertical velocity and turbulence Turbulent dissipation rate Vertical velocity Layer-averaged vertical velocity, 5-pt smooth

Summary Statistics 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 (5 th -95 th percentiles) and while symbol shows daily mean Storm & deep cloud regime Low-level stratiform cloud regime

Case Study Example 29 August 2008 From the Cloud Radar Perspective 1)Low-level mixed- phase stratocumulus (ice falling from liquid cloud layer) 2)Brief mixed-phase strato/alto-cumulus 3)Multiple high cirrus clouds and a suggestion of possible liquid water at times. Cloud Radar Moments

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

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.

Case Study Example 29 August 2008 Retrieval Results: BL-Cloud Interactions During first ½ of day (decoupled cloud and surface): 1)Relatively more ice than liquid production. 2)Thinner liquid layer. 3)Turbulence decreases towards surface. During second ½ of day (well-mixed): 1)Less ice production and more liquid water 2)Thicker liquid layer. 3)Turbulence constant towards surface

Case Study Example 29 August 2008 Examine Profiles at 3 times 1)Decoupled 2)Multi-layer 3)Well-mixed 123

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

Case Study Example 29 August 2008 Broad updrafts and narrow downdrafts on scales of 1-2 km Focus on Circulations during “Well-Mixed” period 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

Please contact me: 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). Research Interests & Potential Collaborations

Extra slides

Case Study Example 29 August 2008 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. The Situation Low-level, stratiform mixed- phase cloud (ice falling from liquid). Short period with a second mixed-phase layer at 1.8 km

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