Cloud Physical Properties:
Description and examples


  1. Goal of the Cloud Physical Product product
  2. Cloud Physical Product algorithm description
  3. List of inputs for Cloud Physical Product
  4. Coverage and resolution
  5. Description of Cloud Physical Product outputs
  6. Example of Cloud Physical Product visualisation
  7. Example of Cloud Physical Product, additional products, visualisation

Goal of the Cloud Physical Properties product

The Goal of the Cloud Physical Properties (cpp) package is to give a more detailed insight into micro-physical conditions of clouds. This means the thermodynamic phase of the cloud particles at the upper part of the cloud and the vertical integrated liquid water path. In addition to these also other cloud micro-physical parameters are retrieved. These additional parameters are made available as they may be of interest to some users. But they are not validated and are not part of the official product.

Cloud Physical Properties algorithm description

A central step within the cpp retrieval is an iterative process wherein the convergence of cloud optical thickness and cloud particle size is tested. First pre-calculated Look-Up Tables (lut) for ice-phase are used and if this does not succeed liquid water luts are used. The finally used lut-set leads directly to the cloud phase product. In case of water-clouds, the vertically integrated liquid water content is derived from an analytic relation, using auxiliary data (see below).

List of inputs for Cloud Physical Properties

pps products as input: Cloud Mask

Satellite data: 0.6 microns, 10.8 microns and (1.6 or 3.7 microns), from avhrr or from viirs.

Auxillary data:

Coverage and resolution

These products are available in full imager resolution and for the whole field of view, provided that all requirements are met. Day light is required for the Cloud Physical Properties product.

Description of Cloud Physical Properties outputs

Main output

There are two official products of Cloud Physical Properties:

Cloud Phase Classes
Class number Class name
-1 Unprocessed
0 Cloud free
1 Cloud phase: liquid
2 Cloud phase: ice

Additional output

There are three additonal products of Cloud Physical Properties:

Example of Cloud Physical Properties visualisation

Cloud Phase
noaa19_20120514_1125_16826.mesanX.cpp_cph.thumbnail.jpg colour scheme no data
cloud free, sea
cloud free, land
cloud phase: liquid
cloud phase: ice
Liquid Water Path

Here an example image of the pps Cloud Physical Properties product over northen Europe is displayed. The data are from a noaa19 overpass (orbit 16826) May 14,2012, 11:25 UTC, as received and processed at smhi, Norrköping, Sweden. The corresponding rgb images using avhrr channel 0.6µm,0.9µm,11µm and 3.7µm,11µm,12µm are shown below for comparison with the Cloud Physical Properties.

The cloud physical properties image shown here has been generated with the nwcsaf/pps software. It displays only part of the information available in the product. Also the hdf-viewer (hdfview) available from ncsa is recommended.

noaa19_20120514_1125_16826.mesanX.cpp_lwp.thumbnail.jpg (383000 bytes) noaa19_20120514_1125_16826.mesanX.cpp_cph.thumbnail.jpg (325000 bytes)
noaa19_20120514_1125_16826.mesanX.avhrr.ch_06_09_11.thumbnail.jpg (476000 bytes) noaa19_20120514_1125_16826.mesanX.avhrr.ch_37_11_12.thumbnail.jpg (476000 bytes)

Example of Cloud Physical Properties, additional products, visualisation

The Cloud Physical Properties also have some additional products, they are not validated, but the are produced together with official products. The case displayed is the same one as above: a noaa19 overpass (orbit 16826) May 14,2012, 11:25 UTC, over northern Europe.
Ice Water Path
Cloud Optical Thickness
Effective Radius