Calibration of non‐catching precipitation measurement instruments: A review

Abstract

Non-catching type gauges are the emerging class of in situ precipitation measurement instruments. For these instruments, rigorous testing and calibration are more challenging than for traditional gauges. Hydrometeors characteristics like particle size, shape, fall velocity and density must be reproduced in a controlled environment to provide the reference precipitation, instead of the equivalent water flow used for catching-type gauges. They are generally calibrated by the manufacturers using internal procedures developed for the specific technology employed. No agreed methodology exists, and the adopted procedures are rarely traceable to internationally recognized standards. The EURAMET project 18NRM03 'INCIPIT' on 'Calibration and accuracy of non-catching instruments to measure liquid/solid atmospheric precipitation', funded by the European Metrology Programme for Innovation and Research (EMPIR), was initiated in 2019 to investigate calibration and accuracy issues of non-catching measuring instruments used for liquid/solid atmospheric precipitation measurement. A survey of the existing models of non-catching type instruments was initially performed and this paper provides an overview and a description of their working principles and the adopted calibration procedures. Both literature works and technical manuals disclosed by manufacturers are summarized and discussed, while current limitations and metrological requirements are identified.

Investigation of the Wind-Induced Airflow Pattern Near the Thies LPM Precipitation Gauge

“…Furthermore, the lack of moving parts and the reduced maintenance required make them especially suitable for use in harsh environments and automatic weather stations, fostering their incremental adoption. The most relevant factors still preventing a widespread diffusion of NCGs are the lack of standardised calibration procedures and correction algorithms to compensate for instrumental and environmental biases [1].…”

Adjustment of one-minute rain gauge time series using co-located drop size distribution and wind speed measurements

“…Note that the reference disdrometer is subject to wind-induced biases itself, as demonstrated by Něspor et al (2000) for a now outdated version of the 2DVD and by Chinchella et al (2021) for the Thies LPM optical disdrometer. Further insights could be therefore achieved by obtaining bias corrected DSD measurements, a topic which is not addressed in this paper.…”

“…Among various applications, disdrometers can be used to improve the integral measurements of precipitation (cumulated depth and intensity) obtained from traditional gauges. Optical disdrometers (Lanza et al, 2021) are widely used to obtain suitable PSD and fall velocity measurements. The two-dimensional video disdrometer (2DVD), manufactured by the Johanneum Research Institute, demonstrated high performance and is used in various scientific works (see Kruger and Krajewski, 2002).…”

A review of video‐based rainfall measurement methods

“…The commonly used empirical formulas are shown in Table 3. The empirical formula of raindrop terminal velocity formula proposed by Atlas et al (1973) based on Doppler weather radar data has been widely used (Jiang et al, 2019; Lanza et al, 2021; Liu et al, 2018).…”

“…The commonly used empirical formulas are shown in Table 3. The empirical formula of raindrop terminal velocity formula proposed by Atlas et al (1973) based on Doppler weather radar data has been widely used (Jiang et al, 2019;Lanza et al, 2021;Liu et al, 2018). Similar to weather radar and microwave link rainfall measurements, the terminal velocity assumption is often used in video-based rainfall calculations (Allamano et al, 2015;Jiang et al, 2019;Wang, Wang, Liu, Zhu, et al, 2022).…”