Abstract:

Ewing-type heat flow meters are widely used for heat flow measurements in harsh environments because of their safety and convenience. When using a Ewing-type heat flow meter, the geothermal gradient of seafloor sediments is obtained by in situ measurements while the thermal conductivity of sediment samples is measured in the laboratory. Due to the stake effect, the insertion depth of the sampler in situ is not always consistent with the length of a recovered sample, so it can be difficult to accurately match the measurement positions for thermal conductivity and geothermal gradients, leading to errors up to 3.5 mW·m–2. Based on the principle that heat flow values of the same station at different depths are relatively consistent, a minimum standard deviation method was designed in this study to determine the optimal deviation of Ewing heat flow meter operations. According to an analysis of data collected from 12 stations during China's ninth scientific Arctic expedition, the standard deviation of heat flow values at each depth of the same station decreased from 8.4 mW·m^–2 to 3.8 mW·m^–2 after the minimum standard deviation method was applied, which is a variation amplitude of about 9% of the average heat flow value.

Key words: Arctic, heat flow, thermal conductivity, geothermal gradient, minimum standard deviation