Ångström exponent errors prevent accurate visibility measurement

Atmospheric Measurement Techniques

article

Guo, Hengnan¹  Zhang, Zefeng¹  Jiang, Lin¹  An, Junlin¹  Zhu, Bin¹  Kang, Hanqing¹  Wang, Jing¹ 

[1] Key Laboratory for Aerosol–Cloud–Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology

DOI  :  10.5194/amt-14-2441-2021

学科分类：内科医学

来源: Copernicus Publications

【 摘 要 】

Visibility is an indicator of atmospheric transparency, and it is widely used in many research fields, including air pollution, climate change, ground transportation, and aviation. Although efforts have been made to improve the performance of visibility meters, a significant error exists in measured visibility data. This study conducts a well-designed simulation calibration of visibility meters, which proves that current methods of visibility measurement include a false assumption, leading to the long-term neglect of an important source of visibility error caused by erroneous values of Ångström exponents. This error has two characteristics, namely (1) independence, which means that the magnitude of the error is independent of the performance of the visibility meter. It is impossible to reduce this error by improving the performance of visibility meters. The second characteristic is (2) uncertainty, which means the magnitude of the error does not show a clear change pattern but can be substantially larger than the measurement error of visibility meters. It is impossible to accurately estimate the magnitude of this error or its influence on visibility measurements. Our simulations indicate that, as errors in visibility caused by erroneous values of Ångström exponents are inevitable using current methods of visibility measurement, reliable visibility data cannot be obtained without major adjustments to current measurement methods.

【 授权许可】

CC BY