Standards for in Situ current measurement

Abstract

Historically, current sensors have been calibrated and intercompared to determine their accuracy and to develop trust in the quality of their data collected. In a more mature technology, standards are established to quantify quality, trustworthiness, and accuracy of measurement. For current meters we do not have standards beyond physical standards of length and time upon which we can claim current meter quality and have relied instead on best practice and intercomparison to judge suitability and trustworthiness for various applications. The measurement of current is more difficult than measurement of scalars such as pressure or temperature, since, to begin with, velocity of fluid is a vector but also it has variability over small scales in space and time. Inherently, flow may be divided into mean (current), oscillatory (wave), and chaotic flow (turbulence). Thus, attributes of a current sensor for measurement of global transport of heat and momentum may be different from those of one to measure surface wave spectra, which may differ again from one to measure boundary layer stress.