The New BCMT Magnetic Database

摘要

The "Bureau Central de Magnetisme Terrestre" (BCMT) is a French organization in charge of the processing and distribution of magnetic data from 16 observatories (AAE, AMS, BNG, BOX, CLF, CZT, DRV, KOU, LZH, MBO, PAF, PHU, PPT, QSB, TAM, TAN), including those run in cooperation with foreign countries. The goal of this project is to carefully check all BCMT data and make them available on a public website in IAGA-2002 format. Data include hourly, daily, monthly and annual means as well as minute values when available. This task is quite simple for data dating from the INTERMAGNET era data, since occasional errors and discontinuities are known and well documented on CD-ROMs. However, some difficulties arise for older data, such as: missing or hard-to-find information on sampling rate, instruments and centering of hourly values; discrepancies between data in numerical format, data printed in yearbooks and data currently available in World Data Centers; spikes; undocumented data corrections. Such problems are occasional, but ought to be consistently tackled prior to scientific usage of old magnetic data.