ABSTRACT

This study highlights a significant methodological and practical issue involving the use of a magnetic compass in aeolian studies in the field. Geomagnetic declination can significantly affect field measurements of wind direction from anemometers as well as measurement of the orientation of geomorphic features such as sand dunes, depending on geographic location. It is therefore surprising how often methodological descriptions of published aeolian studies, including those in southern Africa, neglect to describe any declination corrections applied to field measurements or instrumental records. This results in uncertainty in the validity of data reported in such studies, particularly where actual wind directions may be very different (>20° in some cases) from measured values. Drawing from examples in the literature from southern Africa and other key locations globally, this study discusses the need for greater clarity in the declination corrections applied when wind direction is being measured and reported, especially where wind datasets from different sources are being used or integrated, or when published studies are being compared.

摘要

这项研究突出了一个重要的方法和实际问题，涉及在该领域的风成研究中使用磁罗盘。根据地理位置，地磁偏角会显着影响风速计对风向的现场测量以及对沙丘等地貌特征方向的测量。因此，令人惊讶的是，对已发表的风成研究（包括在南部非洲的研究）的方法论描述经常忽略描述应用于实地测量或仪器记录的任何赤纬校正。这导致此类研究中报告的数据有效性的不确定性，特别是在实际风向可能与测量值有很大差异（在某些情况下 > 20°）的情况下。