Cloud base heights and atmospheric backscatter observations from expedition SAS, Arctic Ocean, 2021
John Prytherch, Sonja Murto, Michael Tjernström
Cloud base heights and atmospheric backscatter data are obtained from a lidar ceilometer instrument. The observed data include direct cloud-base heights from thresholding backscatter, derived so-called 'cloud scenes' with cloud base height and cloudiness for multiple cloud layers from a clustering technique, and also the lidar backscatter profile directly from the instrument.
The instrument was deployed on the 7th top deck of the Swedish icebreaker Oden during the expedition SAS (Synoptic Arctic Survey) covering a large area including parts of Amundsen Basin, Nansen Basin, the North Pole, Lomonosov Ridge, Morris Jesup Rise and the Yermak Plateau. Measurements ran continuously between July 27 and September 13, 2021.
AtmosphereWeather observationsCloudsCloud base heightCloud fractionLidar backscatterBackscatter profilesMeteorologyArcticArctic OceanSynoptic Arctic SurveySAS 2021 expeditionIcebreaker Oden
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Data description
The dataset includes two NetCDF (.nc) files zipped into one zip-file. Total file size is about 458 MB (compressed 153 MB).
There is also an associated readme_ACAS_SAS2021_CL31_v1.0.rtf file that provides a list of all variable names, with short explanations and units and further details of data and processing.
Dimensions
Dimensions for the fields are time, some variables have a second dimension. The two NetCDF files have the following different time resolutions:
ACAS_SAS2021_CL31_1min_v1_0.nc: 1 minute time averaged dataACAS_SAS2021_CL31_20min_v1_0.nc: 20 minute time averaged data
The data was concatenated from the native format and averaged.
Comments
Measurement system
The data was obtained from a lidar ceilometer from Vaisala (Vaisala CL31). Clouds are detected by thresholds on backscatter radiation from an eye-safe lidar. When the lowest cloud layer is not covering the sky, multiple cloud layers can be detected. The instrument also provides a cloud scene product based on the last 10 minutes of data, using a proprietary clustering algorithm that in addition to cloud base height also provides a cloud fraction for each layer. The original backscatter profile is also provided.
Quality control
No data quality control is applied, except for adding the instrument height to the cloud base height variables.
Data creators' roles
The instrument system was continuously logging and was monitored by the Stockholm University Meteorology team onboard Oden:
- John Prytherch (operator and dataset creator and responsible for the instrument system)
- Sonja Murto (operator)
- Michael Tjernström (project PI)
Project
Synoptic Arctic Survey (SAS) 2021 expedition. These data are part of the Arctic Climate Across Scales (ACAS) project, funded by the Knut and Alice Wallenberg Foundation (grant no. 2016-0024). Project PI Michael Tjernström (MISU).
Publisher
Bolin Centre Database
License
First name
John
Last name or organisation
Prytherch
Email address
Address
Department of Meteorology; Stockholm University
Postal code
10691
City
Stockholm
Country
Sweden
GCMD science keyword
Earth science > Atmosphere
GCMD location
Ocean > Arctic Ocean
Dataset language
English
Begin date
2021-07-27
End date
2021-09-13