MARKIS: the Dutch marine database and its quality control system

The Royal Netherlands Meteorological Institute (KNMI) has a long history of collecting and archiving marine data. In 1854 Dutch merchant ships started to transfer their collected observations regularly to the just-founded KNMI. The data came to the KNMI in the logbook form as agreed at the Brussels conference in 1853 (Quetelet, 1854). Once the KNMI received the data, they were processed and archived. Nowadays, the KNMI is still active in the field of collecting, processing and archiving marine data. The data collecting routine was subject to many changes during the past one and a half century. These changes include differences in logbook models, SHIP codes, archive formats, storing devices (media) and processing. Around 1980 a first step was undertaken to digitally archive all marine observations in one format. Due to changing WMO coding standards, later observations got another format. Until recently the marine data were available digitally, but had different formats for different periods and a plain file structure only. Recently, the new Dutch marine database has been developed (MARKIS). All marine data are stored in this relational database for archiving, processing and retrieval. This database contains the Dutch marine ship data from 1854 until now, as well as the marine data from the other Voluntary Observing Ships (VOS) that are exchanged internationally under WMO regulations (CMM-XI, Rec. 11).

Often data quality appear to be problematic, especially when data sources, processes or human interference change over time. With respect to the quality controlled historical data, an additional problem arises as the procedure followed is not readily available anymore; e.g. adjustments were often made without archiving why and how it was done. To overcome this kind of problems in future and to provide information about the different steps in the quality control procedures, a quality control module has been developed. This quality control module is incorporated in the marine database and enables the monitoring of the quality control process in its different stages. Moreover, metadata concerning former types of archiving are preserved. This appears valuable in the quality control and homogenising procedures because different types of archiving introduce their own type of errors.

This report starts with a short review of the history of the marine-data collection and archiving during one and a half century. It continues with a description how the archive is structured nowadays in the new designed ‘MARKIS’ database. Furthermore, its quality control structure is highlighted in more detail. Finally, the operational procedures to keep the database up-to-date are described.