Abstract. Tritium (3H) as a constituent of the water molecule is an
important natural tracer in hydrological sciences. The anthropogenic tritium
introduced into the atmosphere unintentionally became an excellent tracer of
processes on a time scale of up to 100 years. A prerequisite for tritium
applications is to know the distribution of tritium activity in
precipitation. Here we present a database of isoscapes derived from 41
stations for amount-weighted annual mean tritium activity in precipitation
for the period 1976 to 2017 on spatially continuous interpolated 1 km×1 km grids for the Adriatic–Pannonian region (called the AP3H_v1 database), with a special focus on post-2010
years, which are not represented by existing global models. Five stations
were used for out-of-sample evaluation of the model performance,
independently confirming its capability of reproducing the spatiotemporal
tritium variability in the region. The AP3H database is capable of
providing reliable spatiotemporal input for hydrogeological application at
any place within Slovenia, Hungary, and their surroundings. Results also show a
decrease in the average spatial representativity of the stations regarding
tritium activity in precipitation from ∼440 km in 1970s, when
bomb tritium still prevailed in precipitation, to ∼235 km in the 2010s. The post-2010 isoscapes can serve as benchmarks for
background tritium activity for the region, helping to determine potential
future local increases in technogenic tritium from these backgrounds. The
gridded tritium isoscape is available in NetCDF-4 at
https://doi.org/10.1594/PANGAEA.896938 (Kern et al., 2019).
Isoscape of amount-weighted annual mean precipitation tritium (<sup>3</sup>H) activity from 1976 to 2017 for the Adriatic–Pannonian region – AP<sup>3</sup>H_v1 database
