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Abstract

The Global Heat Flow Database of the International Heat Flow Commission (IHFC) is currently under fundamental revision. Here, we present a critical assessment of the terrestrial heat-flow-density data for Germany. The collected legacy data from Germany cover entries from 596 heat-flow locations over a time span of more than 60 years, showing differences in documentation and the availability of metadata. To assess the data, we follow a multi-step procedure: first, we screened the original literature, updated the heat flow data and revised them for completeness and reproducibility. Database entries with missing data essential for heat flow determination (like temperature gradient, thermal conductivity) are flagged as not reliable as they cannot be scientifically reproduced nor quality assessed. This strict procedure is necessary for setting up a dataset following scientific criteria and results in a reduction of the original data set by almost 80% to 138 locations. These were assessed in terms of methodological quality and labeled for different overruling effects, like paleoclimate, heat refraction, or fluid movements. The (area-weighted) average terrestrial heat flow for Germany is 78 ± 7 mWm^-² which is by almost 20% higher compared to earlier estimates (ca. 65 mWm^-²). The regional average heat flow across Germany varies by the order of 40 %. However, considering a radius of 10 km around each location, the heat flow remains uncertain for ca. 90% of the German onshore area, which raises the demand for new systematic heat-flow measurements in Germany.