How do Clouds Alter the State of the Atmospheric Column? Diabatic Heating Profiles –Latent Heating –Condensation (warming) –Evaporation (cooling) –Net column latent heating = Precipitation mass * L –where L = latent heat –Radiative Heating –Incoming solar –Outgoing IR –Net column radiative heating= net incoming minus net outgoing –Profiles of diabatic heating impact atmospheric dynamic and thermodynamic structure
Representing Clouds in Climate Models 55-N 60-N 172-W157-W CLIMATE MODEL GRID CELL Weather Forecast Model Grid Cell Cloud Resolving Models: Less Than Width Of Lines
What Cloud Properties Change the Radiative Heating Rate Profile? 1.Amount of the sky that contains cloud 2.Thickness of individual clouds and layers 3.Composition Contain ice crystals, liquid water, or both? Particle sizes? Particle concentrations? 4.Height in the atmosphere
How Does the Location of Cloud Impact the Surface Temperature? Low Clouds Space ~ 2-km High Clouds ~10-km COOLINGWARMING
What We Know About Solar Radiation and Clouds Solid theoretical foundation for interaction between a single, spherical liquid cloud droplet and sunlight Sun Cloud Droplet Scattered Light
What We Know About Solar Radiation and Clouds Some theoretical foundation for interaction of sunlight and simple ice crystal shapes
What We Wish We Knew About Solar Radiation and Clouds 1.How do we compute the total impact of a huge collection of diverse individual cloud particles? 2.What are the regional differences in cloud composition, coverage, thickness, and location in the atmosphere? 3.If we knew (1) and (2), how do we summarize all of this information so that it can be incorporated into a climate model?
What We Know About Outgoing Terrestrial Radiation and Clouds Good theoretical foundation for interaction of terrestrial radiation and cloud water content (liquid clouds). Particle: –radius somewhat important in thin liquid clouds –shape and size somewhat important in high level ice clouds (cirrus) Aerosols?
Surface Radiation Calibration Facility Meteorological Tower Multiple Radars Multiple Lidars 2-km Clouds Through a SODA STRAW!
What types of remote sensors do we use to make cloud measurements? Visible and Infrared Sky Imagers Vertically-Pointing Lasers (LIDARs) –Measure the height of the lowest cloud base –Below cloud concentrations of aerosol and water vapor –Beam quickly disperses inside cloud Cloud Radars –Information about cloud location and composition Microwave Radiometers –Measure the total amount of liquid water in atmosphere –Can’t determine location of liquid –Presently not measuring total ice content
Visual Images of the Sky cloud coverage (versus cloud fraction) simple! digitize images and … daytime only integrated quantity
Negligible Return Cloud and Aerosol ParticlesCloud droplets Surface 10-km 20-km 24 Hours Laser Data from Southern Great Plains Ice Clouds Low Clouds No Signal 7:00 pm7:00 am7:00 pm time
Small Cloud ParticlesTypical Cloud ParticlesVery Light Precipitation Surface 10-km 20-km Cloud Radar Data from Southern Great Plains Black Dots: Laser Measurements Of Cloud Base Height 7:00 pm7:00 am7:00 pm time
Small Cloud ParticlesTypical Cloud ParticlesVery Light Precipitation Surface 10-km 20-km Cloud Radar Data from Southern Great Plains Black Dots: Laser Measurements Of Cloud Base Height Thin Clouds Insects 7:00 pm7:00 am7:00 pm time
Surface 2-km 10-km LaserRadar Base Radar Echo Top Base Top Low Radar Sensitivity Radar Echo Radar Echo Microwave Radiometer Emission
Evolution of Cloud Radar Science Cloud Structure and Processes Cloud Statistics Cloud Composition
5-km 10-km 15-km Cloud Top Height Probability 1% 10% Tropical Western Pacific Jan 1999 June 1999 3% 1% 10% 3% Probability