Comment on essd-2022-203

Abstract

The Sheshan geomagnetic observatory (IAGA code SSH), China was built in Xujiahui, Shanghai in 1874 and moved to Sheshan, Shanghai at the end of 1932. So far, SSH has a history of nearly 150 years. It is one of the earliest geomagnetic observatory in China and one of the geomagnetic stations with the longest history in the world.In this paper, we present the rescue and quality control of the historical data at Sheshan observatory (SSH) from 1933 to 2019. The rescued data are the absolute hourly mean values of D, H and Z components. Some of these data are paper-based records, and some are stored in a floppy disk in BAS, DBF, ACCESS and other file formats. After digitization and format transformation, we imported the data into the Toad database to achieve the unified data management. We performed statistics of continuity rate, visual analysis, outliers detects and data correction on the stored data. Then we conducted the consistency test of daily variation and secular variation by comparing the corrected data with these of the reference observatory data, and the computational data of the COV-OBS model, respectively. The consistency test revealed fairly good agreement. However, the individual data should be used with caution, because these data are suspicious values, but there is not any explanation or change registered in the available metadata and logbooks. Finally we present an example of the datasets in discriminating geomagnetic jerks. The digitized and quality-controlled AHMVs data are available at: https://doi.org/10.5281/zenodo.6584285 (Zhang et al, 2022).