ECV Products and Requirements for Cloud Properties
These products and requirements reflect the Implementation Plan 2016 (GCOS-200). GCOS is reviewing and will update the requirements as part of their contribution to the UNFCCC Global Stocktake and the current state of the discussion is reflected on the web page "2022 requirement update".
| PRODUCT | DEFINITION | FREQ. | RES. | REQUIRED MEASUREMENT UNCERTAINTY | STABILITY | STANDARDS/ REFERENCES |
| Cloud Amount | 2D field of fraction of sky filled by cloud | 3hr | 50km/NA | 0.01-0.05 | 0.01/ decade | ESA CCI CMUG tables (http://www.esa-cmug-cci.org/) |
| Cloud Top Pressure | Pressure of the top of the cloud (highest cloud in the case of multi-layer clouds) | 3hr | 50km/NA | 15-50hPa, | 3-15hPa | |
| Cloud Top Temperature | Temperature of the top of the cloud (highest cloud in case of multi-layer clouds) (Km) | 3hr | 50km/NA | 1-5K; | 0.25K/ decade | |
| Cloud Optical Depth | Effective depth of a cloud from the viewpoint of radiation extinction. OD = exp(-K.?z) where K is the extinction coefficient [km-1 ] and ?z the vertical path [km] between the base and the top of the cloud and the reference wavelength to be specified in the metadata. (dimensionless) | 3hr | 50km/NA | 10%, | 2% | |
| Cloud Water Path(liquid an ice) | 2D Field of atmospheric water in the liquid/solid phase, integrated over the total column (g/m2) | 3hr | 50km/NA | 25%; | 5% | |
| C, effective particle radius (liquid + ice) | Ratio of integral of water droplets size distribution in volume divided by integral in area (µm) | 3hr | 50km/NA | 1µm; | 1µm/ decade |
