Here are a few concerns regarding the validity of this product. They are
not meant to deter you from using it, but rather to encourage you to exercise
caution in its interpretation.
- First and foremost, this is an experimental
- Cloud optical depth at large solar zenith angle and at night have large
uncertainties (actually, the uncertainty is unknown).
- Precipitable water estimates from the AVHRR are not very robust, and can
be in error by a factor of 2. This affects the surface albedo retrieval and
the calculation of radiative fluxes.
- A number of the cloudy sky parameter retrievals require a brightness
temperature and/or reflectance value under the cloud. The way this is
estimated is through an interpolation of nearby clear pixels. While this
often works very well, it sometimes introduces relatively large errors.
Simply put, it's a difficult problem with no obvious solution!