Precipitation IntensityandCloud Physics Brad Eck April 26, 2007
Data Sources • Precipitation Intensity • North American Regional Reanalysis (NARR) • netCDF (thanks to Cedric) • Units: kg/m^2/s mm/s • Cloud Physics • Moderate Resolution Imaging Spectrometer (MODIS) • Optical Thickness
Optical Thickness • “…a measure of how opaque a medium is to radiation passing through it.” http://scienceworld.wolfram.com/physics/OpticalDepth.html • “The (dimensionless) line integral of the absorption coefficient…along any path in a … medium.” http://amsglossary.allenpress.com/glossary/search?id=optical-thickness1
Source: King et. al., “Remote sensing of cloud, aerosol, and water vapor properties from the Moderate Resolution Imaging Spectrometer (MODIS),” IEEE Trans. Geosci. Remote Sens. 30, 2-27 (1992).
Sprechen Sie Englisch? • Optical thickness combines droplet size, water content and cloud height to give a normalized cloud size • Bigger clouds should have a higher precipitation intensity