Instruments and methods - A physically based method for correcting temperature profile measurements made using thermocouples
Instruments and methods - A physically based method for correcting temperature profile measurements made using thermocouples
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DOI：
10.3189/172756507782202892
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发表时间：
2007-01-01
影响因子：
3.4
通讯作者：
Albert, M. R.
中科院分区：
文献类型：
--
作者：
Cathles, L. Madagan;Cathles, L. M., III;Albert, M. R.
在至少几个，可能是许多北极和南极热电偶数据集中，高频（昼夜）温度变化同时发生在多个深度处，这些深度被雪隔开。这些温度变化不可能是由来自表面的热传导引起的，因为它们的幅度太大，并且不存在随深度的相位滞后，并且它们不可能是由热平流引起的，因为所需的空气通量大于可用的空气通量。相反，同步温度变化（STV）似乎起源于数据记录仪的盒子内，如热电偶样偏移电压，电线加热或热敏电阻误差。STV可以通过要求温度在测量温度的最大深度处随时间平滑地变化来校正。以这种方式确定的校正电压在施加到其他深度处的热电偶时校正整个数据集。该方法成功地去除了幅度高达3.8摄氏度的24小时周期的STV，并且上级于通常用于校正热电偶数据的平均技术，因为它不会引入虚假（非物理）温度变化。所描述的校正方法可以应用于所有热电偶数据，其中温度测量已经在类似于0.5米的深度进入积雪。修正应允许更多的物理过程和参数信息，以更有信心地从现有的坚定的温度数据提取。对STV及其可能原因的识别也表明了未来如何收集更好的数据。
High-frequency (diurnal) temperature variations occur simultaneously at multiple depths separated by meters of snow in at least several and probably many Arctic and Antarctic thermocouple datasets. These temperature variations cannot be caused by heat conduction from the surface because their amplitudes are too large and there is no phase lag with depth, and they cannot be caused by heat advection because the air flux required is greater than is available. Rather, the simultaneous temperature variations (STVs) appear to originate within the box that houses the data logger as thermocouple-like offset voltages, wire heating or thermistor error. The STVs can be corrected by requiring that the temperatures vary smoothly with time at the greatest depth at which temperature is measured. The correction voltage determined in this fashion, when applied to the thermocouples at other depths, corrects the entire dataset. The method successfully removes STVs with 24 hour period that are up to 3.8 degrees C in amplitude, and is superior to the averaging techniques commonly used to correct thermocouple data because it introduces no spurious (non-physical) temperature variations. The correction method described can be applied to all thermocouple data where temperature measurements have been made at depths similar to 0.5 m into the snowpack. The corrections should allow more physical process and parameter information to be extracted more confidently from existing firm temperature data. Identification of the STVs and their probable cause also suggests how better data might be collected in the future.