Mapping of permafrost surface and active layer properties using GPR: A comparison of frequency dependencies

Ground penetrating radar (GPR) was used to detect internal features and conditions in the active layer of Zackenberg valley in North-East Greenland. For about 16 years there has been a monitoring programme that registers the physical and biological processes in the ecosystem. We aim to improve the monitoring accuracy of the active layer development and estimated soil water content. We used two different GPR frequencies to study their performance in High-Arctic cryoturbated soils. Here we present the analysis of the signal received by quantifying the power of the signal that is reflected from the top of the permafrost and from the internal features in the unfrozen soil. These results will be further used to determine the distribution of dielectric heterogeneities to support water content estimated from the same profiles. Comparing results from 400 and 800 MHz, we found that although both frequencies are suitable to measure thickness and to detect features in the active layer, the 400 MHz gives a better impression of the influence of the dielectric contrast effect from top of the permafrost zone which can be used to quantify the soil water content.