Shallow hot-point drill system for active layer temperature measurement along Zhongshan–Dome A traverse, Antarctica

Yazhou Li,Xiao Li,Xiaopeng Fan,Yinke Dou,Pavel G Talalay,Jialin Hong,Siyu Lu,Shichang Kang

doi:10.1017/aog.2020.87

Abstract

AbstractIn glaciology, snow–firn temperature at 10 m is considered a representation of the mean annual air temperature at the surface (MAAT) of the studied site. Although MAAT is an important parameter in ice-sheet investigations, it has not been widely measured in Antarctica. To measure the 10 m snow–firn temperature in Antarctica, a shallow hot-point drill system is designed. In this simple and lightweight system, a hot-point drill can melt boreholes with a diameter of 34 mm in the snow–firn to a depth of 30 m and a temperature sensors string can measure the borehole temperature precisely. In the 2018/19 field season, 16 boreholes along the Zhongshan–Dome A traverse were drilled, and the borehole temperature was measured. Although certain problems existed pertaining to the hot-point drill, a total depth of ~244 m was successfully drilled at an average penetration rate of ~10 m h−1. After borehole drilling, ~12–15 h were generally required for the borehole to achieve thermal equilibrium with the surroundings. Preliminary results demonstrated that the 10 m snow–firn temperature along the traverse route was affected by the increasing altitude and latitude, and it decreased gradually with an increase in the distance from Zhongshan station.

Highlights

As an important parameter in ice-sheet investigation, mean annual air temperature at the surface (MAAT) is an indicator of the thermal state of the local climate
It is generally accepted that the snow–firn temperature measured at a 10 m depth is a close approximation of the MAAT (Mock and Weeks, 1966; Loewe, 1970)
It is worth to be mentioned that the snow–firn temperature at 10 m depth cannot be always equal to MAAT, especially in the glaciers where the surface melting occurs (Zagorodnov and others, 2006)

Summary

Introduction

As an important parameter in ice-sheet investigation, mean annual air temperature at the surface (MAAT) is an indicator of the thermal state of the local climate. It is generally accepted that the snow–firn temperature measured at a 10 m depth is a close approximation of the MAAT (Mock and Weeks, 1966; Loewe, 1970). This makes it possible to estimate MAAT by measuring the temperature in a borehole in areas where there are no meteorological records. The depth of the mean annual air temperature for a given site depends on the local snow–firn properties, accumulation rate and possibly wind conditions (Zagorodnov and others, 2012). In Antarctica, the MAAT usually decreases from mid-latitude to the South Pole, from the coastal regions to inland and from sea level to high altitude

Methods

Results

Conclusion