High resolution temperature measurement technique for measuring marine heat flow

Abstract

High resolution temperature measurement technique is one of the key techniques for measuring marine heat flow. Basing on Pt1000 platinum resistance which has the characteristics of high accuracy and good stability, we designed a bridge reversal excitation circuit for high resolution temperature measurement. And the deep ocean floor in-situ test results show that: (1) temperature deviation and peak-to-peak resolution of the first version circuit board (V1) are 1.960-1.990 mK and 0.980-0.995 mK at 1.2-2.7A degrees C, respectively; and temperature deviation and peak-to-peak resolution of the second circuit board (V2) are 2.260 mK and 1.130 mK at 1.2-1.3A degrees C, respectively; (2) During the 2012NSFC-IndOcean cruise, seafloor geothermal gradient at Ind2012HF03, -07 and -12 stations (water depth ranges from 3841 to 4541 m) were successfully measured, the values are 59.1, 75.1 and 71.6A degrees C/km, respectively. And the measurement errors of geothermal gradient at these three stations are less than 3.0% in terms of the peak-to-peak resolution. These indicate that the high resolution temperature measurement technique based on Pt1000 platinum resistance in this paper can be applied to marine heat flow measurement to obtain high precision geothermal parameters.