The CLARA-A2.1 (CM SAF cLoud, Albedo and surface Radiation dataset from AVHRR data - Edition 2.1) record provides cloud properties, surface albedo and surface radiation parameters derived from the AVHRR sensor onboard polar orbiting NOAA and METOP satellites. The edition 2.1 includes and temporally extends the second edition of the record (CLARA-A2) now providing data from 1982/01 to 2019/06, i.e., for 37.5 years.
CLARA-A2.1 features a range of cloud products: cloud mask, cloud top temperature/pressure/height (CTT/CTP/CTH), cloud thermodynamic phase (CPH), cloud optical thickness (COT), cloud particle effective radius (REF) and cloud water path (CWP). Cloud products are available as monthly and daily averages as well as daily resampled global products (Level 2b) for individual satellites. Cloud parameter results are also presented as single-parameter distributions (frequency histograms of CTP, CTT, COT, REF and CWP) and multi-parameter distributions (joint frequency histograms of COT, CTP and CPH for daytime conditions). Surface albedo is presented as monthly and pentad (5 day) averages and is derived using all available data during the studied period. Surface radiation products are provided as monthly averages for the downwelling shortwave (including also daily averages) and the down- and upwelling longwave components. All monthly and daily averages are available on a 0.25°x0.25° global grid. Surface albedo and cloud products are also provided in two equal area grids with a resolution of 25 km x 25 km covering the polar regions. Daily resampled cloud products (level 2b) are provided in a global grid with a resolution of 0.05°x0.05°. For the latter, also a probabilistic cloud mask is added as an experimental product.
The data record can be ordered via the Web User Interface .
More information on the data record is available from the DOI page: 10.5676/EUM_SAF_CM/CLARA_AVHRR/V002_01
|Product Name||Product Acronym|
|Fractional Cloud Cover||CFC|
|Joint Cloud property Histogramm||JCH|
|Cloud Top Height, Temperature, Pressure||CTO|
|Liquid Wather Path||LPW|
|Ice Water Path||IWP|
|Cloud Optical Thickness||COT|
|Surface Incoming Shortwave Radiation||SIS|
|Surface Outgoing Longwave Radiation||SOL|
|Surface Downward Longwave Radiation||SDL|
|Demonstration product (daily resampled): Probabilistic Cloud Mask (included in CMA as additional data layer)|
|Time period||1982/01 – 2019/06|
|Temporal resolution||daily mean, pentad mean, monthly mean, monthly histograms (depending on product) + daily subsampled global cloud products|
|Spatial coverage||global on a regular latitude/longitude grid (polar areas: equal area)|
|Spatial resolution||0.25° x 0.25° for monthly and daily means, 1°x1° for JCH, 0.05° x 0.05° for daily subsampled products and 25 km x 25 km for polar areas|
|Data Format||NetCDF 4, Climate and Forecast (CF) Metadata Convention v1.6|
Karlsson, K.-G., Anttila, K., Trentmann, J., Stengel, M., Meirink, J. F., Devasthale, A., Hanschmann, T., Kothe, S., Jääskeläinen, E., Sedlar, J., Benas, N., van Zadelhoff, G.-J., Schlundt, C., Stein, D., Finkensieper, S., Håkansson, N., and Hollmann, R.: CLARA-A2: The second edition of the CM SAF cloud and radiation data record from 34 years of global AVHRR data, 17, 5809–5828, https://doi.org/10.5194/acp-17-5809-2017, 2017.
Cloud properties - Product User Manual (PUM)
Cloud properties - Validation Report (VAL)
Cloud properties - Algorithm Theoretical Basis Document (ATBD)
Surface Albedo - Product User Manual (PUM)
Surface Albedo - Validation Report (VAL)
Surface Albedo - Algorithm Theoretical Basis Document (ATBD)
Surface radiation - Product User Manual (PUM)
Surface radiation - Validation Report (VAL)
Surface radiation - Algorithm Theoretical Basis Document (ATBD)
MSt / Nov 2020