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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 MeasurementDescription*InstrumentsTimeline
Cloud drop size (at cloud top)Vertical profile of the size distribution of liquid water drops, 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 ].4 instruments
Cloud ice (column/profile)Vertical profile of atmospheric water in the solid phase (precipitating or not). Requested 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].6 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 ].7 instruments
Cloud ice effective radius (column/profile)Area weighted mean radius of the cloud droplets.1 instrument
Cloud liquid water (column/profile)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].26 instruments
Cloud optical depthImpact of the cloud water column on radiation propagation - Physical unit: [ dimensionless ] - Accuracy unit: [ % ].15 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: [ % ].15 instruments
* Description adapted from WMO.
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