Quality assessment of permafrost thermal state and active layer thickness data in GTN-P

The Global Terrestrial Network for Permafrost (GTN-P, gtnp.org) established the new ‘dynamic’ GTN-P Database (gtnpdatabase.org), which targets the Essential Climate Variable (ECV) permafrost, described by the thermal state of permafrost (TSP) and active layer thickness (ALT). This paper outlines the requirements for assessing the GTN-P data quality. Our aim is to conceive and discuss useful data quality indices as a basis for the 2nd official GTN-P National Correspondents Meeting in Quebec, September 2015. We describe the TSP and ALT data structures and the importance of precise metadata for the reliability of sound statements on the state and changes of permafrost. We define the most critical parameters related to quality assessment of TSP (borehole depth, number of sensors per depth, recording interval, sensor calibration) and ALT (grid structure, null values and exceeded maximum values, time consistency). We conceive and discuss a set of potential (to be reviewed at the GTN-P meeting) data quality indices by distinguishing between different borehole depths and spatial and temporal data dimensions of TSP and ALT datasets