Measurements
AVHRR, NOAA
Local Observation Time and Length of Data Record
1:30 AM and 1:30 PM : 1983-2020
7:30 AM and 7;30 PM : 1992–2020
Spatial Resolution
1×5 km at nadir with 4km sampling distance (AVHRR GAC)
Cloud Detection
6 Bayesian classifiers derived from CALIPSO.
Retrieval Methodology
CEM, CT → CP, phase (water/ice), COD, CRE, CWP
PATMOS-X takes full advantage of all five channels of AVHRR. Cloud detection is based on Bayesian classifiers derived from CALIPSO, the retrieval is based on Optimal Estimation Method. First cloud pressure and cloud emissivity are retrieved using two IR channels. Then cloud optical depth and effective particle radius are obtained from solar channels so that finally cloud water path can be derived from them.
Ancillary input
- NCEP reanalysis profiles (V1)
- MODIS snow mask
- radiative transfer + particle model
References
Heidinger, A. K., A. T. Evan, M. J. Foster, and A. Walther, 2012: A Naïve Bayesian Cloud Detection Scheme Derived from CALIPSO and Applied within PATMOS-x. J. Appl. Meteor. Climatol., 51, 1129-1144.
Walther, A., and A. Heidinger, 2012: Implementation of the Daytime Cloud Optical and Microphysical Properties Algorithm (DCOMP) in PATMOS-x. J. Appl. Meteor. Climatol., 51, 1371-1390.