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New Climate Data Record available: CLARA-A3 CM SAF’s Cloud, Radiation and Surface Albedo data record, AVHRR-based, Edition 3
The CLARA-A3 record provides cloud properties and radiation parameters derived from the AVHRR sensor onboard polar orbiting NOAA and METOP satellites (Karlsson et al., 2023). CLARA-A3 is the latest edition of CLARA with previous editions documented in Karlsson et al. (2013) and Karlsson et al. (2017). CLARA-A3 covers the time period 1979/01/01 until 2020/12/31 as climate data record (CDR), but is operationally extended as interim climate data record (ICDR) to the present with a latency of 10 days.
Figure Left: Global map of CLARA-A3 monthly mean cloud top pressure for 2012/06 from NOAA-19. Right: Global map of the uncertainty of the monthly mean cloud top pressure for 2012/06 from NOAA-19.
The AVHRR measurement input to the CLARA-A3 retrieval algorithms is the EUMETSAT PyGAC AVHRR Fundamental Data Record (FDR) Release 1 (DOI:10.15770/EUM_SEC_CLM_0060). CLARA-A3 features a range of cloud products: cloud mask, cloud top temperature/pressure/height, cloud thermodynamic phase, and (for liquid and ice clouds separately) cloud optical thickness, particle effective radius and cloud water path. Additionally, cloud droplet number concentration and cloud geometrical thickness are provided for liquid clouds. Furthermore, a range of radiation products are included in CLARA-A3: surface black-sky, white-sky and blue-sky albedo; surface downwelling short- and longwave radiation as well as surface net radiation; top-of-atmosphere (TOA) upwelling short- and longwave radiation. Cloud products are available as monthly and daily averages and histograms, as well as daily resampled global products (Level 2b) for individual satellites. Surface albedo is presented as monthly and pentad (5 day) averages. Surface and TOA radiation products are provided as daily and monthly averages. All averages are available on a 0.25° x 0.25° global grid. Surface albedo and selected cloud products are also provided on 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°. CLARA-A3 features a comprehensive set of documentation including User Manuals, Validation Reports and Algorithms Theoretical Baseline Documents (see links below).
The data record can be ordered via the Web User Interface
More information on the data record is available from the DOI page: http://dx.doi.org/10.5676/EUM_SAF_CM/CLARA_AVHRR/V003
| Fractional Cloud Cover | CFC | Surface Albedo (Black-,White-,Blue-sky) | SAL |
| Joint Cloud property Histogramm | JCH | Surface Incoming/Net Shortwave Radiation | SIS / SNS |
| Cloud Top Height, Temperature, Pressure | CTO | Surface Down /Net Longwave Radiation | SDL / SNL |
| Cloud Phase | CPH | Surface Radiation Budget | SRB |
| Liquid Wather Path1,2 | LWP | ToA Reflected Shortwave Flux | SRF |
| Ice Water Path1 | IWP | ToA Outgoing Longwave Radiation | OLR |
| 1 includes optical thickness, effective radius 2 includes geometrical thickness, cloud droplet number concentration | |||
| Time period | 1979/01 – present |
|---|---|
| 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 v1.7 |
Documentation:
- Karlsson, K.-G., Riihelä, A., Müller, R., Meirink, J. F., Sedlar, J., Stengel, M., Lockhoff, M., Trentmann, J., Kaspar, F., Hollmann, R., and Wolters, E.: CLARA-A1: a cloud, albedo, and radiation dataset from 28 yr of global AVHRR data, Atmos. Chem. Phys., 13, 5351–5367, https://doi.org/10.5194/acp-13-5351-2013
- Karlsson, K.-G., Anttila, K., Trentmann, J., Stengel, M., Fokke Meirink, J., 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, Atmos. Chem. Phys., 17, 5809–5828, https://doi.org/10.5194/acp-17-5809-2017
- Karlsson, K.-G. et al., CLARA-A3: The third edition of the AVHRR-based CM SAF climate data record on clouds, radiation and surface albedo covering the period 1979 to 2023,
submitted to Earth Syst. Sci. Data, 2023
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)
TOA radiation - Product User Manual (PUM)
TOA radiation - Validation Report (VAL)
TOA radiation - Algorithm Theoretical Basis Document (ATBD)
MSt / April2023