A measurement of the albedo of thick cirrus clouds at 3.9 microns

• Published in: Geophysical research letters Vol. 29; no. 10; pp. 9 - 1 to 9-3
• Main Author: Kidder, S Q
• Format: Journal Article
• Language: English
• Published: 15.05.2002
• ISSN: 0094-8276

Cirrus (ice) clouds are often semitransparent (transmittance greater than zero, but less than one), which makes it difficult to measure fundamental cloud properties, such as albedo. This paper explores a way to measure the albedo of thick cirrus clouds (zero transmittance) at 3.9 microns using GOES Imager data. In brief, the 10.7-micron GOES data are used to separate the cirrus clouds into temperature classes. Then the measured 3.9-micron radiance is plotted against the cosine of the solar zenith angle. A theoretical relationship between radiance and solar zenith angle is used to extract the albedo. The result is that thick cirrus clouds have an albedo of 1.08 +/- 0.05 percent at 3.9 microns. The albedo of thick cirrus is a step toward the measurement of the transmittance of thin cirrus. (Author)