Attenuated backscatter profiles from the CALIOP satellite lidar are used to estimate cloud base heights of lower-troposphere liquid clouds (cloud base height below approximately 3 km). Even when clouds are thick enough to attenuate the lidar beam (optical thickness > 5), the technique provides cloud base heights by treating the cloud base height of nearby thinner clouds as representative of the surrounding cloud field. Using ground-based ceilometer data, uncertainty estimates for the cloud base height product at retrieval resolution are derived as a function of various properties of the CALIOP lidar profiles. Evaluation of the predicted cloud base heights and their predicted uncertainty using a second, statistically independent, ceilometer dataset shows that cloud base heights and uncertainties are biased by less than 10%.
CBASE provides two files for each CALIOP VFM input file: one using a 40 km window to detect the cloud field base height, and one using a 100 km window. (The input CALIOP VFM dataset is organized by the daytime/nighttime half of each orbit.) The file name pattern is
CBASE<resolution>_<date>T<time><day/night>.nc (identical to the input
CALIOP VFM file name with the exception of the product name). Files are organized into subdirectories by half-orbit start date.
Mülmenstädt, Johannes; Sourdeval, Odran; Henderson, David S.; L’Ecuyer, Tristan S.; Unglaub, Claudia; Jungandreas, Leonore; Böhm, Christoph; Russell, Lynn M.; Quaas, Johannes (2018). Using CALIOP to estimate cloud-field base height and its uncertainty: the Cloud Base Altitude Spatial Extrapolator (CBASE) algorithm and dataset. World Data Center for Climate (WDCC) at DKRZ. https://doi.org/10.1594/WDCC/CBASE
In case no cloud base heights are detected within a half-orbit, no output file is produced. Otherwise, each CALIOP VFM input file results in a 40 km-r...
Description
In case no cloud base heights are detected within a half-orbit, no output file is produced. Otherwise, each CALIOP VFM input file results in a 40 km-resolution and a 100-km resolution CBASE file. The measurement quality is reported as a quantitative uncertainty estimate for each cloud field.
FAIR
F-UJI result: total 66 %
Description
Summary: Findable: 6 of 7 level; Accessible: 2 of 3 level; Interoperable: 3 of 4 level; Reusable: 5 of 10 level
SQA - Scientific Quality Assurance 'approved by author'
Result Date
2018-04-13
Technical Quality Assurance (TQA)
TQA - Technical Quality Assurance 'approved by WDCC'
Description
1. Number of data sets is correct and > 0: passed; 2. Size of every data set is > 0: passed; 3. The data sets and corresponding metadata are accessible: passed; 4. The data sizes are controlled and correct: passed; 5. The temporal coverage description (metadata) is consistent to the data: passed; 6. The format is correct: passed; 7. Variable description and data are consistent: passed
Method
WDCC-TQA checklist
Method Description
Checks performed by WDCC. The list of TQA metrics are documented in the 'WDCC User Guide for Data Publication' Chapter 8.1.1
[1] DOIMülmenstädt, Johannes; Sourdeval, Odran; Henderson, David S.; L'Ecuyer, Tristan S.; Unglaub, Claudia; Jungandreas, Leonore; Böhm, Christoph; Russell, Lynn M.; Quaas, Johannes. (2018). Using CALIOP to estimate cloud-field base height and its uncertainty: the Cloud Base Altitude Spatial Extrapolator (CBASE) algorithm and dataset. doi:10.5194/essd-2018-43
[2] DOIMülmenstädt, Johannes; Sourdeval, Odran; Henderson, David S.; L'Ecuyer, Tristan S.; Unglaub, Claudia; Jungandreas, Leonore; Böhm, Christoph; Russell, Lynn M.; Quaas, Johannes. (2020). Using CALIOP to estimate cloud-field base height and its uncertainty: the Cloud Base Altitude Spatial Extrapolator (CBASE) algorithm and dataset. doi:10.5194/essd-10-2279-2018