Some considerations on the infrared cloud forcing

Long-wave spectral cloud forcing is computed for realistic clouds of various optical thickness embedded in the tropical and subarctic winter standard atmospheres. The strict connections between the integrated long-wave cloud forcing (LCF) and cloud's altitude and transmissivity are shown. LCF,...

Full description

Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres
Main Authors: Rizzi R., Maestri T.
Format: Article in Journal/Newspaper
Language:English
Published: 2003
Subjects:
Online Access:https://hdl.handle.net/11585/956459
https://doi.org/10.1029/2003jd003428
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2003JD003428
Description
Summary:Long-wave spectral cloud forcing is computed for realistic clouds of various optical thickness embedded in the tropical and subarctic winter standard atmospheres. The strict connections between the integrated long-wave cloud forcing (LCF) and cloud's altitude and transmissivity are shown. LCF, especially in presence of ice clouds, grows almost linearly with cloud transmissivity, and largest values are found in presence of high and opaque cirri. We have also considered the effect of incomplete spectral coverage in broadband long-wave radiometry when estimating LCF. The error has been computed as a function of edge cutoff (two different filters are used) and cloud's transmissivity and top altitude. Uncorrected measurements from sensors with incomplete spectral coverage generally underestimate the real LCF, especially for the highest cirrus clouds in the tropics. A correction is possible since the percentage error is practically constant with cloud's transmissivity.