ALBERT

Description: The GRACE (Gravity Recovery and Climate Experiment) satellites, which comprises two spacecraft, GRACE-A and GRACE-B, were launched on 17 March 2002 into a near-circular, polar (inclination = 89◦ ) orbit with an initial altitude of about 490 km. The two satellites follow each other at a distance of about 200 km. The primary objective of the GRACE mission is to provide global high-resolution models of the Earth’s gravity field. The instruments supporting our study are the K-Band Ranging System (KBR), and the GPS Space Receiver (GPS). The K-Band Ranging System (KBR) system is the key science instrument of GRACE which measures the dual one-way range change between both satellites with a precision of about 1 μm per second. From the KBR1B data we can get the change of Total Electron Content (TEC). In addition the GPS Navigation Data (GNV1B) can provide us the position of the two satellites. From these data we can derive the average electron density between the two satellites. The data are stored as daily ASCII files using the file naming convention 'KBRNE_YYYY_MM_DD.dat'. Headers in each data file contain a short name for each column. A more detailed description is provided in the readme file.

Description: GRACE-FO carries a magnetometer as part of its attitude orbit control system (AOCS). The magnetometer does not belong to the scientific payload of the mission. However, after postprocessing of the data, information on the geomagnetic field and on electric currents in near Earth space are derived. Each GRACE-FO satellite (GF1 and GF2) carries two fluxgate magnetometers (FGM), an active one, FGM A, and a redundant one, FGM B. So far, the redundant magnetometers were not switched and are not included in the data set. The provided data consists of raw magnetic field data as provided by L1b (RAW), Magnetic field data aligned, calibrated and corrected (ACAL_CORR), CHAOS7 magnetic model predictions for core, crustal and large-scale magnetospheric field (CHAOS7), Magnetic coordinates (APEX) and Radial and field-aligned currents derived from magnetic data in ACAL_CORR (FAC). The data are provided in NASA CDF format (https://cdf.gsfc.nasa.gov/).

Description: Matzka et al. (2021) describe the state of the Kp index 70 years after its introduction and serve as a reference for users of the IAGA-endorsed Kp index as well as for the derived indices ap, Ap, Cp and C9 in their definitive and nowcast version as well as for the International Quiet and Disturbed Days. This dataset is provided by GFZ and derived from indices or near real-time geomagnetic observatory data provided by 13 contributing observatories. Please cite this data publication as well as the accompanying publication (Matzka et al., 2021) when using the Kp index or any of the derived indices obtained from this dataset or from its copies provided by GFZ or other institutions. The Kp index The Kp index was introduced by Bartels (1949). We follow here generally the notation of Bartels (1957). A comprehensive list of references on the Kp index is provided in Matzka et al. (2021), which also describes the near real-time distribution of the indices. DOI and versioning With the introduction of the DOI ‘https://doi.org/10.5880/Kp.0001’ for the dataset, the DOI landing page and the associated FTP server linked to this DOI become the dataset's primary archive (while the other established index distribution mechanisms at GFZ will be maintained in parallel). With the DOI, the dataset can grow with time, but a change of the data, once published, is not possible. If necessity arises in the future to correct already published values, then the corrected dataset will be published with a new DOI. Older DOIs and data sets will then still be available. For each DOI, an additional versioning mechanism will be available to document changes to the files such as format changes, which do not affect the integrity of the data. The DOI 10.5880/Kp.0001 identifies the current version.

Description: This data publication includes the half-hourly Hp30 and ap30 indices as well as the hourly Hp60 and ap60 indices. All are unitless and collectively denoted as Hpo or Hpo index family. The dataset is based on near real-time geomagnetic observatory data provided by 13 contributing observatories. It is derived and distributed by GFZ German Research Centre for Geosciences. When using the Hpo index, please cite this data publication as well as the accompanying publication Matzka et al. (in prep), which serves as documentation of the Hpo index family. The dataset is organised in yearly files, which, for the current year, are updated on a monthly basis. Typically, during the second week of a month, the data for the previous month is appended to the current year's file. The files are in ASCII files and start with header lines marked with # (hash). The Hpo index was developed within the H2020 project SWAMI (grant agreement No 776287) and is produced by Geomagnetic Observatory Niemegk, GFZ German Research Centre for Geosciences. It derives from the same 13 geomagnetic observatories that also contribute to the Kp index (Matzka et al., 2021). They are listed as contributors to this data publication. With the introduction of the DOI ‘https://doi.org/10.5880/Hpo.0001’, this DOI landing page and the associated FTP server linked to the DOI become the primary archive of Hpo (while the other established index distribution mechanisms at GFZ will be maintained in parallel). With the DOI, the dataset can grow with time, but a change of the data, once published, is not possible. If necessity arises in the future to correct already published values, then the corrected dataset will be published with a new DOI. Older DOIs and data sets will then still be available. For each DOI, an additional versioning mechanism will be available to document changes to the files such as header or format changes, which do not affect the integrity of the data. The DOI https://doi.org/10.5880/Hpo.0001 identifies the current version. A format description is provided in the data download folder. As ocean tides are usually described as a superposition of so-called partial tides, the presented mass variations can be attributed to single partial tide frequencies and are thus represented for single partial tide frequencies. Here, not only the effect of direct gravitation exerted by the ocean water is included but also gravity variations due to the elastic yielding of the solid earth in response to water mass redistribution (the load tide) are allowed for. The information describing the partial tides has been transformed to fully normalized Stokes Coefficients describing in-phase and quadrature fields as those are especially handy for gravimetric purposes. The next section describes the creation of the data in more detail. As support for the COSC drilling project, an extensive seismic survey took place in 2014 in and around the newly drilled borehole COSC-1. The active seismic survey, among others, consisted of a high-resolution Zero-Offset Vertical Seismic Profiling (ZOVSP) experiment where seismic receivers were placed inside the borehole. For the seismic source signal a hydraulic hammer source (VIBSIST 3000) was used and activated over a period of 20 s as a sequence of impacts with increasing hit frequency. The wavefield was recorded in the borehole by 15 three-component receivers using a Sercel Slimwave geophone chain with an inter-tool spacing of 10 m. The ZOVSP was designed to result in a geophone spacing of 2 m over the whole borehole length. The source was about 30 meters away from the borehole. For component rotation, a check shot position was located about 1.9 km away from the borehole. This data set contains two data sets: (1) the decoded, pre-processed three-component shot gather, and (2) the final-processed shot gather of only the vertical component.

Description: The Gravity field and steady-state ocean circulation explorer (GOCE) satellite mission carries three platform magnetometers. After careful calibration, the data acquired through these can be used for scientific purposes by removing artificial disturbances from other satellite payload systems. This dataset is based on the dataset provided by Michaelis and Korte (2022) and uses a similar format. The platform magnetometer data has been calibrated against CHAOS7 magnetic field model predic-tions for core, crustal and large-scale magnetospheric field (Finlay et al., 2020) and is provided in the ‘chaos’ folder. The calibration results using a Machine Learning approach are provided in the ‘calcorr’ folder. Michaelis’ dataset can be used as an extension to this dataset for additional infor-mation, as they are connected using the same timestamps to match and relate the same data points. The exact approach based on Machine Learning is described in the referenced publication. The data is provided in NASA CDF format (https://cdf.gsfc.nasa.gov/) and accessible at: ftp://isdcftp.gfz-potsdam.de/platmag/MAGNETIC_FIELD/GOCE/ML/v0204/ and further de-scribed in a README.

Description: The Gravity Recovery and Climate Experiment-Follow-On (GRACE-FO) satellite mission, consisting of two satellites, each carry a magnetometer as part of its attitude orbit control system (AOCS). After careful calibration, the data acquired through them can be used for scientific purposes by removing artificial disturbances from other satellite payload systems. This dataset is based on the dataset provided by Michaelis et al. (2021, https://doi.org/10.5880/GFZ.2.3.2021.002) and uses a similar format. The platform magnetometer data has been calibrated against CHAOS-7 magnetic field model predictions for core, crustal and large-scale magnetospheric field (Finlay et al., 2020, https://doi.org/10.1186/s40623-020-01252-9) and is provided in the ‘chaos’ folder. The calibration results using a Machine Learning approach are provided in the ‘calcorr’ folder. Michaelis’ dataset can be used as an extension to this dataset for additional information, as they are connected using the same timestamps to match and relate the same data points. The exact approach based on Machine Learning is described in the referenced publication. Additionally, in the folder ‚fac’, field-aligned current derived from the magnetic field data are provided. There exists a similar dataset with calibrated magnetic data from the GOCE satellite mission under https://doi.org/10.5880/GFZ.2.3.2022.002 (Styp-Rekowski et al., 2022).