Digital Object Identifier
Entry information for CLARA_AVHRR_V002
Here you find the details of your selected DOI acronym and the links to order the described products.
Title
CLARA-A2: CM SAF cLoud, Albedo and surface RAdiation dataset from AVHRR data - Edition 2
Citation
Karlsson, Karl-Göran; Anttila, Kati; Trentmann, Jörg; Stengel, Martin; Meirink, Jan Fokke; Devasthale, Abhay; Hanschmann, Timo; Kothe, Steffen; Jääskeläinen, Emmihenna; Sedlar, Joseph; Benas, Nikos; van Zadelhoff, Gerd-Jan; Schlundt, Cornelia; Stein, Diana; Finkensieper, Stephan; Håkansson, Nina; Hollmann, Rainer; Fuchs, Petra; Werscheck, Martin (2017): CLARA-A2: CM SAF cLoud, Albedo and surface RAdiation dataset from AVHRR data - Edition 2, Satellite Application Facility on Climate Monitoring, DOI:10.5676/EUM_SAF_CM/CLARA_AVHRR/V002, https://doi.org/10.5676/EUM_SAF_CM/CLARA_AVHRR/V002. [BibTeX entry]
Publisher
Satellite Application Facility on Climate Monitoring (CM SAF)
Publication year
2017
Author(s)
Karlsson, Karl-Göran; Anttila, Kati; Trentmann, Jörg; Stengel, Martin; Meirink, Jan Fokke; Devasthale, Abhay; Hanschmann, Timo; Kothe, Steffen; Jääskeläinen, Emmihenna; Sedlar, Joseph; Benas, Nikos; van Zadelhoff, Gerd-Jan; Schlundt, Cornelia; Stein, Diana; Finkensieper, Stephan; Håkansson, Nina; Hollmann, Rainer; Fuchs, Petra; Werscheck, Martin
Description
The CLARA-A2 record provides cloud properties, surface albedo and surface radiation parameters derived from the AVHRR sensor onboard polar orbiting NOAA and METOP satellites. This second edition is the improved and extended follow-up of the first version of the record (Karlsson et al., 2013; CLARA-A1 DOI: 10.5676/EUM_SAF_CM/CLARA_AVHRR/V001) which now covers a 34 year time period (1982-2015). Original visible radiances were inter-calibrated and homogenised, using MODIS data as a reference, before applying the various parameter retrievals. The inter-calibration was based on an original method introduced by Heidinger et al. (2010) which now has been updated (MODIS Collection 6) and extended (six years have been added). CLARA-A2 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. Cloud products are available as monthly and daily averages and also as daily resampled global products (Level 2b) for individual satellites. Cloud parameter results are also presented as multi-parameter distributions (i.e., joint frequency histograms of cloud optical thickness, cloud top pressure and cloud phase) 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. The 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 advancements compared to CLARA-A1 can be summarized as follows: (1) Extended AVHRR measurement record (six years). (2) Upgraded inter-calibration (using MODIS Collection 6 as reference). (3) Significantly improved cloud screening (utilizing CALIPSO-CALIOP data during development). (4) Improved efficiency of cloud top height retrievals (i.e., reduced number of pixels with no retrieval solutions). (5) Improved cloud phase discrimination and ice cloud property retrieval. (6) Improved atmospheric correction using dynamic aerosol optical depths for the full surface albedo data record. (7) Extended product portfolio (i.e., adding daily resampled Level 2b cloud products including experimental cloud probabilities). A summary of the CLARA-A2 characteristics and a comprehensive evaluation of the results are provided by Karlsson et al., (2016). Along with the data, a comprehensive documentation including user guide, algorithm descriptions, reprocessing layout and extensive validation studies, is provided.
Format
NetCDF-4
Version
2.0
Temporal coverage
1982-01-01 - 2015-12-31
Geographic coverage
Latitude: -90.0° S to 90.0° N
Longitude: -180.0° W to 180.0° E
Size
12.4 TiB
Documentation
- Product User Manual (PUM) CLARA-A2 Cloud Products
- Product User Manual (PUM) CLARA-A2 Surface Radiation Products
- Product User Manual (PUM) CLARA-A2 Surface Albedo Product
- Validation Report (VAL) CLARA-A2 Cloud Products
- Validation Report (VAL) CLARA-A2 surface radiation products
- Validation Report (VAL) CLARA-A2 Surface Albedo Product
- Algorithm Theoretical Baseline Document (ATBD) CLARA-A2 Cloud Products
- Algorithm Theoretical Baseline Document (ATBD) Joint Histogram Products
- Algorithm Theoretical Baseline Document (ATBD) Probabilistic Cloud Masks
- Algorithm Theoretical Baseline Document (ATBD) Cloud Mask Products (NWC SAF PPS v2014)
- Algorithm Theoretical Baseline Document (ATBD) Cloud Top Height Products (NWC SAF PPS v2014)
- Algorithm Theoretical Baseline Document (ATBD) Cloud Physical Products (NWC SAF PPS v2014)
- Algorithm Theoretical Baseline Document (ATBD) CLARA-A2 Surface Radiation Products
- Algorithm Theoretical Baseline Document (ATBD) CLARA-A2 Surface Albedo Product
Related publications
- 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, Atmos. Chem. Phys., 17, 5809-5828, doi:10.5194/acp-17-5809-2017, 2017.
- 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, doi:10.5194/acp-13-5351-2013, 2013.
- Heidinger, A.K., Straka III, W.C., Molling, C.C., Sullivan, J.T. and Wu, X.: Deriving an inter-sensor consistent calibration for the AVHRR solar reflectance data record, Int. J. Rem. Sens., 31, 6493-6517, 2010
Auxiliary data
- CLARA-2.1 Auxiliary Data User Guide
- Auxiliary data for global Level 2b products
- Auxiliary data for global Level 3 products
- Auxiliary data for Level 3 products in Northern Polar Region
- Auxiliary data for Level 3 products in Southern Polar Region
Related Data Records
- A previous version of this data record is available from here: DOI:10.5676/EUM_SAF_CM/CLARA_AVHRR/V001.
- This data record is a portion of an extended version: DOI:10.5676/EUM_SAF_CM/CLARA_AVHRR/V002_01.
Data record details and ordering
Products from Polar Orbiting Satellites (LEO)
Cloud phase (CPH)
- Monthly mean (Global),
- Monthly mean (Southern Polar Region),
- Monthly mean (Northern Polar Region),
- Daily mean (Global),
- Daily mean (Southern Polar Region),
- Daily mean (Northern Polar Region)
Cloud top parameters CTT, CTP and CTH (CTO)
- Monthly mean (Global),
- Monthly histogram (Global),
- Monthly mean (Southern Polar Region),
- Monthly mean (Northern Polar Region),
- Daily mean (Global),
- Daily mean (Southern Polar Region),
- Daily mean (Northern Polar Region)
Cloud water path (CWP)
Fractional cloud cover (CFC)
- Monthly mean (Global),
- Monthly mean (Northern Polar Region),
- Monthly mean (Southern Polar Region),
- Daily mean (Global),
- Daily mean (Southern Polar Region),
- Daily mean (Northern Polar Region)
Ice water path (IWP)
- Monthly mean (Global),
- Monthly mean (Southern Polar Region),
- Monthly mean (Northern Polar Region),
- Daily mean (Southern Polar Region),
- Daily mean (Northern Polar Region),
- Daily mean (Global)
Joint cloud property histograms (JCH)
Liquid water path (LWP)
- Monthly mean (Northern Polar Region),
- Monthly mean (Southern Polar Region),
- Monthly mean (Global),
- Daily mean (Global),
- Daily mean (Northern Polar Region),
- Daily mean (Southern Polar Region)
Surface albedo (SAL)
- Pentad mean (Southern Polar Region),
- Pentad mean (Northern Polar Region),
- Pentad mean (Global),
- Monthly mean (Global),
- Monthly mean (Southern Polar Region),
- Monthly mean (Northern Polar Region)