| CEOS EO HANDBOOK – MEASUREMENTS
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Measurements > Atmosphere >
Cloud particle properties and profile
  | A key to climate modelling is to observe and understand the global distribution of clouds, their physical properties, such as thickness and droplet size. Whether a particular cloud will heat or cool the Earth’s surface depends on the cloud’s radiating temperature – and thus its height – and on its albedo for both visible and infrared radiation, which depends on the number and details of the cloud properties. | |
| Detailed Measurement | Description* | Instruments | Timeline |
Cloud drop effective radius
Link:   | Size distribution of liquid water drops, assimilated to spheres of the same volume. Considered as both a 3D field throughout the troposphere and a 2D field at the top of the cloud surface - Measuring Units μm, Uncertainty Units μm | 9 instruments | |
| Cloud ice (column/profile) | Vertical profile of atmospheric water in the liquid phase (precipitating or not). Measured in the troposphere (assumed height: 12 km), and as total column - Physical unit: profile [ g/kg ], total column [g/m2] - Accuracy unit: profile [ % ], total column [g/m2]. | 7 instruments | |
| Cloud ice content (at cloud top) | Vertical profile of the size distribution of ice particles, assimilated to spheres of the same volume. Requested in the troposphere (assumed height: 12 km), and at the cloud top surface - Physical unit: [ mm ] - Accuracy unit: [ mm ]. | 6 instruments | |
| Cloud ice effective radius (column/profile) | Area weighted mean radius of the cloud droplets. | 3 instruments | |
Cloud liquid water (column/profile)
Link: | Vertical profile of atmospheric water in the liquid phase (precipitating or not). Requested in the troposphere (assumed height: 12 km), and as total column - Physical unit: profile [ g/kg ], total column [kg/m2] - Accuracy unit: profile [ % ], total column [kg/m2]. | 24 instruments | |
Cloud optical depth
Link: | Impact of the cloud water column on radiation propagation - Physical unit: [ dimensionless ] - Accuracy unit: [ % ]. | 16 instruments | |
| Precipitation Profile (liquid or solid) | Vertical profile of the precipitation rate - Physical unit: [ g×s-1×m-2 ] (vertical flux of precipitation water mass) - Accuracy unit: [ % ]. | 13 instruments | |
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* Description adapted from WMO.
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