This dataset comprises hourly mean values of the horizontal geomagnetic field component H measured at the geomagnetic observatories Tatuoca (TTB, latitude: -1.205°, longitude: 311.487°, elevation: 5 m, Brazil) and Huancayo (HUA, latitude: -12.050°, longitude: -284.670°, elevation: 3313 m, Peru) for the period January 1st, 1957 to December 31st, 2019.

TTB data from 1957 to May 2008 is described in the scientific publication Soares et al. (2020), to which this data publication is supplement to. This data comes from Observatório Nacional's archives and we expect to submit a final version of this data to WDC Edinburgh at a later point in time. From June 2008 to December 2017 we use hourly mean values calculated from the minute means available at Soares et al (2018). For 2018, we use quasi-definitive data from Observatório Nacional's archives. From January 2019 to July 22nd 2019, we use preliminary data from Observatório Nacional's archives. From July 23rd 2019 to December 2019, we use preliminary data from INTERMAGNET.

For HUA from 1957 to 2001 we give new corrected data here that are based on earlier data publications (Matzka et al, 2017; Matzka et al., 2018). We plan to submit a final version of this data to WDC Edinburgh at a later point in time. From 2002 to 2014 we use definitive data from INTERMAGNET/WDC Edinburgh. From January 2015 to April 2015, we use quasi-definitive data from INTERMAGNET. From May 2015 to December 2019 we use variation data from INTERMAGNET.

The data files are provided in the IAGA-2002 format (https://www.ngdc.noaa.gov/IAGA/vdat/IAGA2002/iaga2002format.html). Geomagnetic observatories are described in e.g. Jankowski and Sucksdorff (1996).