2026-07-17T01:24:46Zhttp://doidb.wdc-terra.org/oaip/oai
oai:doidb.wdc-terra.org:66222026-06-10T09:59:32ZDOIDBDOIDB.GFZ
false4DOIDB.GFZ 10.5880/GFZ.2.3.2018.006 Pick, Leonie Leonie Pick 0000-0002-5266-9764 GFZ German Research Centre for Geosciences, Potsdam, Germany Korte, Monika Monika Korte 0000-0003-2970-9075 GFZ German Research Centre for Geosciences, Potsdam, Germany HMC Index GFZ Data Services 2018 Geomagnetic observatories External magnetic field Magnetospheric currents EARTH SCIENCE > SOLID EARTH > GEOMAGNETISM > GEOMAGNETIC INDICES EARTH SCIENCE > SUN-EARTH INTERACTIONS > IONOSPHERE/MAGNETOSPHERE DYNAMICS > MAGNETIC FIELDS/MAGNETIC CURRENTS EARTH SCIENCE > SUN-EARTH INTERACTIONS > IONOSPHERE/MAGNETOSPHERE DYNAMICS > MAGNETIC STORMS Pick, Leonie Leonie Pick 0000-0002-5266-9764 GFZ German Research Centre for Geosciences, Potsdam, Germany Pick, Leonie Leonie Pick 0000-0002-5266-9764 GFZ German Research Centre for Geosciences, Potsdam, Germany Korte, Monika Monika Korte 0000-0003-2970-9075 GFZ German Research Centre for Geosciences, Potsdam, Germany Thomas, Yannik Yannik Thomas GFZ German Research Centre for Geosciences, Potsdam, Germany Pick, Leonie GFZ German Research Centre for Geosciences, Potsdam, Germany 2018-10-01 1900-01-01/2015-12-31T23:30:00 1915-01-01/2015-12-31T23:30:00 Dataset 10.1029/2018JA026185 https://www.ngdc.noaa.gov/IAGA/vdat/IAGA2002/iaga2002format.html http://www.wdc.bgs.ac.uk/catalog/master.html 1.0 CC BY 4.0 The HMC (Hourly Magnetospheric Currents) index measures the activity of large-scale magnetospheric currents on Earth's surface from 1900 to 2015. It resolves the absolute intensity of low-frequency variations, especially at periods relevant to the solar cycle, more robustly than existing geomagnetic indices. HMC is based on hourly means of vector magnetic field measurements from 34 mid latitude geomagnetic observatories obtained from WDC Edinburgh (http://www.wdc.bgs.ac.uk/catalog/master.html). This data has been manually revised to correct for spikes, jumps and drifts. A detailed description of the derivation method is given in Pick et al. (JGR, 2019) to which these data are supplementary material.


This directory contains the HMC index (hmc1900phor.hor) and the modified observatory data that it is based on (data.zip). The index and the observatory data files are formatted in compliance with the IAGA-2002 ASCII exchange format (https://www.ngdc.noaa.gov/IAGA/vdat/IAGA2002/iaga2002format.html).


Individual file names are composed of:
[IAGA code of observatory] + [first active year during 1900-2015] + [p(provisional)] + [hor(hourly)] + [_mod(modified)].hor


Also included is information on how the data modifications (list in modifications.pdf) were applied (readme.txt).
Spatial and temporal coverage of geomagnetic observatory data from the northern hemisphere. -158 140.186 14.392 56.827 Spatial and temporal coverage of geomagnetic observatory data from the southern hemisphere. -171.775 115.95 -13.807 -43.267 Deutsche Forschungsgemeinschaft http://doi.org/10.13039/501100001659 273423638 Separating multi-decadal internal geomagnetic secular variation and magnetospheric field variations