Cloud Type (CT)


  1. Goal of the Cloud Type product
  2. Cloud Type algorithm summary
  3. Cloud Type outputs

Goal of the Cloud Type product

The main objective of the Cloud Type product is to distinguish between thin and opaque clouds, and provide a rough estimate of the cloud top height, and also try to distinguish between water particle clouds and ice particle clouds. The highest priority is given to the reliable identification of the major cloud categories: low, medium, high, and semi-transparent cirrus.

Cloud Type algorithm summary

The Cloud Type algorithm use input from the Cloud Mask and the Cloud Top Temperature and Height products. The algorithm distinguishes different cloud types using thresholds defined by off-line radiative transfer calculations and a database of interactively collected training targets. Similar to the cloud mask the cloud type algorithm takes satellite imagery input from the sensors avhrr, viirs or modis, on board the following satellite platforms: NOAA, Metop, SNPP/JPSS, and EOS-Terra/Aqua. Besides the satellite data the thresholding algorithm, takes the following as input:

Cloud Type outputs

The Cloud Type output consists of:

Main output

Cloud Type Classes
Class number Class name
1 Cloud free land
2 Cloud free sea
3 Land contaminated by snow
4 Sea contaminated by snow/sea-ice
5 Very low clouds (cloud top less than 0.5km above ground)
6 Low clouds
7 Medium level clouds
8 High opaque clouds
9 Very high opaque clouds
10 Fractional clouds (sub-pixel water clouds)
11 High semi-transparent very thin cirrus
12 High semi-transparent thin cirrus
13 High semi-transparent thick cirrus
14 High semi-transparent cirrus above low or medium level clouds
15 High semi-transparent cirrus above snow or sea-ice
255 Non-processed / No data