Passive and active detection of clouds: Comparisons between MODIS and GLAS observations
Article first published online: 25 FEB 2004
Copyright 2004 by the American Geophysical Union.
Geophysical Research Letters
Volume 31, Issue 4, February 2004
How to Cite
2004), Passive and active detection of clouds: Comparisons between MODIS and GLAS observations, Geophys. Res. Lett., 31, L04108, doi:10.1029/2003GL018859., , , , and (
- Issue published online: 25 FEB 2004
- Article first published online: 25 FEB 2004
- Manuscript Accepted: 29 DEC 2003
- Manuscript Revised: 11 DEC 2003
- Manuscript Received: 17 OCT 2003
 The Geoscience Laser Altimeter System (GLAS), launched on board the Ice, Cloud and Land Elevation Satellite in January 2003 provides space-borne laser observations of atmospheric layers. GLAS provides opportunities to validate passive observations of the atmosphere for the first time from space with an active optical instrument. Data from the Moderate Resolution Imaging Spectroradiometers aboard the Terr and Aqua satellites are examined along with GLAS observations of cloud layers. In more than three-quarters of the cases, MODIS scene identification from spectral radiances agrees with GLAS. Disagreement between the two platforms is most significant over snow-covered surfaces in the northern hemisphere. Daytime clouds detected by GLAS are also more easily seen in the MODIS data as well, compared to observations made at night. These comparisons illustrate the capabilities of active remote sensing to validate and assess passive measurements, and also to complement them in studies of atmospheric layers.