This is a test dataset for data hosted by EUM, available via EUMDAC. ECV Cloud Properties CLARA-A3.
Data description
Data type | Gridded |
|---|---|
Projection | Regular latitude-longitude grid |
Horizontal coverage | Global |
Horizontal resolution | 0.25° x 0.25° |
Vertical coverage | Depends on the variable. Possible values are: surface, top of the atmosphere and total atmospheric column |
Vertical resolution | Single level |
Temporal coverage | 1979 to present |
Temporal resolution | Monthly and daily |
Temporal gaps | February 1985: monthly mean missing. May 1982 to March 1986: few missing daily data |
File format | NetCDF-4 |
Conventions | Climate and Forecast (CF) Metadata Convention v1.6, Attribute Convention for Dataset Discovery (ACDD) 1.3 |
Versions | Edition 3: CLARA-A3, and Edition 2: CLARA-A2 |
Update frequency | Biannual (CLARA-A3): Updates occur twice a year, adding six-month periods with a six-month lag |
Variables
Name | Units | Description |
|---|---|---|
Cloud fraction | % | Fraction of a grid cell which is covered by clouds in relation to the whole grid cell. Files contain the variables: cloud fraction, cloud fraction low-level clouds, cloud fraction mid-level clouds, cloud fraction high-level clouds, cloud fraction day, cloud fraction night. "Cloud fraction" takes into account the entire atmospheric column over the grid cell during the time aggregation period. The other variables are focused on different atmospheric layers and periods of the day. |
Cloud phase | % | The liquid cloud fractional cover is defined as the fraction of liquid cloud pixels per grid square compared to the total number of cloudy pixels in the grid square. Liquid cloud fraction is expressed in percent. File contain the variables: cloud phase day, cloud phase night, defined by Solar Zenith Angle. |
Cloud physical properties of the ice phase | Depends on the variable | Files provide: effective radius of cloud condensed water particles at cloud top, atmosphere optical thickness due to cloud, atmosphere mass content of cloud ice. The effective radius is the area weighted mean radius of the particle size in meter. Optical thickness is a dimensionless quantity measuring how much visible light is prevented passing ice cloud particles in the atmosphere by scattering and absorption. The optical thickness is the integral along the path of radiation of a volume, scattering, absorption or attenuation coefficient. The last variables provides the vertical mass integral of ice cloud particles per area in kg/m2. It is only provided for the daytime, defined by Solar Zenith Angle. |
Cloud physical properties of the liquid phase | Depends on the variable | Files provide: effective radius of cloud liquid water particles at liquid water cloud top, atmosphere optical thickness due to cloud, atmosphere mass content of cloud liquid water. The effective radius is the area weighted mean radius of the particle size in meter. Optical thickness is a dimensionless quantity measuring how much visible light is prevented passing liquid cloud particles in the atmosphere by scattering and absorption. The optical thickness is the integral along the path of radiation of a volume, scattering, absorption or attenuation coefficient. The last variables provides the vertical mass integral of liquid cloud particles per area in kg/m2. It is only provided for the daytime, defined by Solar Zenith Angle. |
Cloud top level | Depends on the variable | Files contain temperature, pressure and height data at the cloud-top under the names: cloud top temperature, cloud top pressure, cloud top height. The cloud-top is defined as the top of the highest cloud in the grid cell. Height is measured from the ground topography in meter. Temperature is given in K and Pressure in hPa. |
Joint cloud property histogram | count | The JCH product is a combined histogram of Cloud Top Pressure (CTP) and Cloud Optical Thickniess (COT) covering the solution space of both parameters. This two-dimensional histogram gives the absolute numbers of occurrences for specific COT and CTP combinations defined by specific bins. It is further separated in liquid and ice clouds. It is only provided for the daytime, defined by Solar Zenith Angle. |