OC3522OC3522 - Remote Sensing of the Atmosphere and Ocean - Summer 2001 2001

Clouds in the InfraredClouds in the Infrared

CloudsClouds and InfraredInfrared Radiation

These high values result in 0 0.5 for IR s

The single scatter albedo (0) describes the scatter vs absorbtion potential and is determined by the imaginary index of refraction

d(,p)0 1

*

(,p)0 0

Let’s assume a perfect window for gaseous absorption,but there is a thick cloud layer in the middle of the atmosphere

LWC

p

0

0

no sfc term

and dp = 1 within the layer at the top of the cloud

so Lt = B(,TCT) What is TCT?

T

TTBB

(from AVHRR CH4)(from AVHRR CH4)

If the atmosphereis dry above cloud top, and the cloud is thick, then TB is a good estimate of the temperature of the cloud top.

NOAA AVHRR 1,2, & 4 channels

cloud heights

DARK BRIGHT

Ocean

Land

Snow/Ice

Cumulonimbus

Cumulus

Stratus/StratocumulusCirrus

Information available in combinations of Visible and IR Imagery:

Brightness

TB

WARM

COLD

Cirrus

Cumulonimbus

Cumulus

Ocean

Land

Snow/Ice

‘An "enhanced-V" signature is noted in the coldest temperatures (the orange/red enhancement) around the outer portions of the thunderstorm cirrus canopy, with a pocket of warmer cloud top temperatures (the yellow/green enhancement) just downstream. This enhanced-V and warm wake signature is a result of upper-level flow being diverted around the intense updraft region of the overshooting tops.’

(from: http://cimss.ssec.wisc.edu/goes/misc/warm_wake.html)

Cloud Drift WindsCloud Drift Winds

Check out for http://cimss.ssec.wisc.edu/goes/satwind/satwind.html details

Multi-spectral Cloud AnalysisThe MODIS (Moderate Resolution Imaging Spectroradiometer) TERRA satellite

Technical InformationA large low-pressure system approached the U.S. East Coast on May 24, 2001, bringing with it forecasts of rain through Memorial Day weekend. This true-color image from th MODIS, flying aboard NASA's Terra satellite, shows the storm while it was centered over Illinois, Iowa, and Missouri. The smoke plume from a large fire northeast of Steinhatchee, Florida, is also visible to the lower right. In the Gulf of Mexico, the bright sun glint reveals a swath of relatively smooth water. The dark area in the patch of sun glint is a cloud shadow.