Long-term all-sky-camera images and evaluated cloud-cover data at Syowa Station, Antarctica

We acquired fish-eye camera (referred to as all-sky-camera) images for detection of cloud distribution in the entire sky and also for use as reference data for optical observations (i.e., sky radiometry and micro-pulse lidar observations) conducted at Syowa Station (69°00′S, 39°35′E), Antarctica, from 2006 to 2022 as a part of a scientific project entitled, “Monitoring observations of the Antarctic aerosols and clouds” as part of the Japanese Antarctic Research Expedition (JARE) program. We evaluated the cloud cover in all the images captured over this period using an objective algorithm based on the brightness of the RGB colors of the images. The importance of cloud properties in climate change models is well known, and obtaining long-term information on cloud properties is important for atmospheric monitoring over Antarctica. This paper describes the archives of all-sky-camera images, evaluated cloud-cover images, and text data of time series of evaluated cloud amounts for this period. Compared with eye observation, the evaluated cloud amounts from the all-sky-camera are underestimated by about 10%. Still, the so-called “U-shaped” frequency distribution is common, where the frequency increases near the maximum and minimum cloud amounts. In addition, we briefly touch on the method of cloud detection. The data are available from the National Institute of Polar Research (NIPR) at https://scidbase.nipr.ac.jp/modules/metadata/index.php?content_id=138.