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Clouds and Climate Through a Soda Straw

Clouds and Climate Through a Soda Straw. Mark Miller. Earth’s Radiation 288 K. Sun’s Radiation 6000 K. Quantity of Radiation. Visible. Infrared. 3. 10. 0.5. Wavelength (micrometers). Visible Satellite Photo. Infrared Satellite Image. Source: NASA/ Earth Radiation Budget Experiment.

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Clouds and Climate Through a Soda Straw

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  1. Clouds and Climate Through a Soda Straw Mark Miller

  2. Earth’s Radiation 288 K Sun’s Radiation 6000 K Quantity of Radiation Visible Infrared 3 10 0.5 Wavelength (micrometers)

  3. Visible Satellite Photo

  4. Infrared Satellite Image

  5. Source: NASA/ Earth Radiation Budget Experiment

  6. “The study of climate and climate change is hindered by a lack of information on the effect of clouds on the radiation balance of earth.” • Ramanathan et al., 1989: Science, 243, 57-62.

  7. Figure 2.10 • IPCC Working Group I (2007)

  8. Representing Clouds in Climate Models CLIMATE MODEL GRID CELL 60-N Weather Forecast Model Grid Cell Cloud Resolving Models: Less Than Width Of Lines 55-N 172-W 157-W

  9. What Cloud Properties Change the Net Radiation Received at the Surface? • Amount of the sky that is covered • Thickness • Composition • Contain ice crystals, liquid water, or both? • Particle sizes? • Particle concentrations? • Height in the atmosphere

  10. How Does the Location of Cloud Impact the Surface Temperature? Space High Clouds ~10-km Low Clouds ~2-km COOLING WARMING

  11. What We Know About Solar Radiation and Clouds • Solid theoretical foundation for interaction between a single, spherical liquid cloud droplet and sunlight • Cloud Droplet • Sun • Scattered • Light

  12. What We Know About Solar Radiation and Clouds • Some theoretical foundation for interaction of sunlight and simple ice crystal shapes

  13. The Real World

  14. What We Wish We Knew About Solar Radiation and Clouds • How do we compute the total impact of a huge collection of diverse individual cloud particles? • What are the regional differences in cloud composition, coverage, thickness, and location in the atmosphere? • If we knew (1) and (2), how do we summarize all of this information so that it can be incorporated into a climate model?

  15. 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?

  16. 2-km CloudsThrough a SODASTRAW! Meteorological Tower Multiple Radars Calibration Facility Multiple Lidars Surface Radiation

  17. The ARM Southern Great Plains Site

  18. SGP Central Facility SODA STRAW Extended Measurement Facilities Wichita Oklahoma City

  19. 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

  20. Visual Images of the Sky • cloud coverage (versus cloud fraction) • simple! digitize images and … • daytime only • integrated quantity

  21. A Time Series

  22. The Past Few Days in Oklahoma…

  23. …have been for the birds! 3/20/08 3/21/08 3/22/08 3/23/08

  24. Sky Imaging • 500 nm • RV Ron Brown • Central Pacific • AOT=0.08 • AMF • Niamey, Niger • AOT=2.5-3 • Sea of Japan • AOT=0.98

  25. Laser Data from Southern Great Plains 20-km No Signal 10-km Low Clouds Ice Clouds Surface time 7:00 pm 7:00 am 24 Hours 7:00 pm Negligible Return Cloud and Aerosol Particles Cloud droplets

  26. V=4500m

  27. V=700m, Mass Concentration=1,700mg m-3

  28. Niamey, Niger, Africa • 20 Cloud Droplets • 15 Cloud and/or Aerosol Height (km) • 10 • LIQUID CLOUDS • 5 • Biomass Burning • Dust Negligible Return • 0 • 1200 • 0000 • 0000 Time (UTC)

  29. Cloud Dust Lake Chad • Dust product (upper) and GERB OLR (lower) for 1200UT on 8 March 2006

  30. At a Given Wavelength A Cloud Particle At Different Wavelengths Energy Returned to Radar Energy Returned to Radar radius6 wavelength-4 Size of Cloud Particle Radar Wavelength

  31. 94 GHz 35 GHz Maximum Propagation Distance Energy Absorbed by Atmosphere 10-15 km 20-30 km 3.2 mm 8 mm Radar Wavelength

  32. The DOE Cloud Radars

  33. Cloud Radar Data from Southern Great Plains 20-km Black Dots: Laser Measurements Of Cloud Base Height 10-km Surface time 7:00 pm 7:00 am 7:00 pm Small Cloud Particles Typical Cloud Particles Very Light Precipitation

  34. Cloud Radar Data from Southern Great Plains 20-km Black Dots: Laser Measurements Of Cloud Base Height 10-km Insects Thin Clouds Surface time 7:00 pm 7:00 am 7:00 pm Small Cloud Particles Typical Cloud Particles Very Light Precipitation

  35. Top Radar Echo Low Radar Sensitivity 10-km Base Radar Echo Top Base 2-km Emission Radar Echo Surface Microwave Radiometer Laser Radar

  36. Evolution of Cloud Radar Science • Cloud Structure and Processes • Cloud Statistics • Cloud Composition

  37. Cloud Transition Azores Applications of Surface-Based Cloud Observing Systems Example: Marine Cloud Transitions Solid Overcast Broken Cloud

  38. Application of Surface-Based Remote Sensing to a Cloud “Problem” • Marine Stratocumulus Transition

  39. THEORY Mid-latitudes Tropics 2 km 0.5 km Ocean Surface OBSERVED Mid-latitudes Tropics 2 km 0.5 km Ocean Surface

  40. Tropical Western Pacific Jan 1999 June 1999 15-km 10-km 5-km Cloud Top Height 3% 1% 3% 10% 1% 10% Probability Probability

  41. Retrieving Liquid Cloud Composition Mode Radius?? Height Width Mode Radius = + Number + Height Particle Size Height Radar Echo Intensity Number Concentration?? Number Concentration Total Liquid Water (Microwave Radiometer)

  42. Liquid Cloud Particle Mode Radius 6 4 Height (km) 2 0 time 7:00 pm 7:00 am 7:00 pm 25 17 1 4 10 Micrometers

  43. Active and Passive Cloud Remote Sensors (cont.) • Wind Profiler • 75-m, 6-min resolution • 915 MHz [1270-1400 MHz COPS] • Minimum Height: 120-m • Maximum height: 5.5-km • Atmospheric Emitted Radiance Interferometer (AERI) • 3-19.2 mm (1 cm-1 resolution) • 6-min resolution (20-30 sec possible for COPS) • 1.3 degree field-of-view

  44. AERI Spectra

  45. Analysis of the Impact of Clouds on Radiation Remotely-Sensed Information about Cloud Structure and Composition Existing Theoretical Models of Radiation Transfer Through Clouds Compute the Energy Budgets at the Surface and Top-of-Atmosphere Compare with Coincident Measurements of the Energy Budget

  46. Meteorological Models • Global Climate Model (GCM) • Forecast Period: Decades to Centuries • Resolution: ~300-km x 300-km • Crude Representations of Many Processes • Numerical Weather Prediction Model (NWP) • Forecast Period: Hours to a Few Days • Resolution: 29-km x 29-km • Better Representations of Many Processes • Cloud Resolving Model (CRM) • Forecast Period: Hours • Resolution: 1-km x 1-km • Detailed Representations of Processes

  47. Super-Parameterizations: The Grabowski, Randall, and Arakawa Scheme CLIMATE MODEL GRID CELL 60-N 5-10 years? 2-Dimensional Cloud Resoving Model 3-D Simulation 55-N 172-W 157-W

  48. Summary • Collecting and analyzing large data sets to better understand cloud behavior • Observations are more compatible with evaluation of cloud resolving models than current GCMs • New “super-parameterizations” in GCMs appears to be the path forward: 5-10 years • Based on cloud resolving models

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