A comparison of rainfall measurements from multiple instruments

Abstract

Simultaneous observations of rainfall collected by a tipping bucket rain gauge (TBRG), a weighing rain gauge (WRG), an optical rain gauge (ORG), a present weather detector (PWD), a Joss–Waldvogel disdrometer (JWD), and a 2-D video disdrometer (2DVD) during January to October 2012 were analyzed to evaluate how accurately they measure rainfall and drop size distributions (DSDs). For the long-term observations, there were different discrepancies in rain amounts from six instruments on the order of 0% to 27.7%. The TBRG, WRG, and ORG have a good agreement, while the PWD and 2DVD record higher and the JWD lower rain rates when <i>R</i> > 20 mm h⁻¹, the ORG agrees well with JWD and 2DVD, while the TBRG records higher and the WRG lower rain rates when <i>R</i> > 20 mm h⁻¹. Compared with the TBRG and WRG, optical and impact instruments can measure the rain rate accurately in the light rain. The overall DSDs of JWD and 2DVD agree well with each other, except for the small raindrops (<i>D</i> < 1 mm). JWD can measure more moderate-size raindrops (0.3 mm < <i>D</i> < 1.5 mm) than 2DVD, but 2DVD can measure more small-size raindrops (<i>D</i> < 0.3 mm). 2DVD has a larger measurement range; more overall raindrops can be measured by 2DVD than by JWD in different rain rate regimes. But small raindrops might be underestimated by 2DVD when <i>R</i> > 15 mm h⁻¹. The small raindrops tend to be omitted in the more large-size raindrops due to the shadow effect of light. Therefore, the measurement accuracy of small raindrops in the heavy rainfall from 2DVD should be handled carefully

Effect of the Resolution of Tipping-Bucket Rain Gauge and Calculation Method on Rainfall Intensities in an Andean Mountain Gradient

“…This indicator was used as measure to compare the accuracy of the calculated rainfall intensities using the TC and CS method and the data of the DRTB gauges [26,41]. For Zhurucay, the intensity given by the LPM was adopted as the reference, whose resolution (0.01 mm) is 10 times higher than the resolution of the most accurate Texas TB rain gauge used in this study, and at least 20 times higher than the widely applied Davis TB rain gauge in the Andes region.…”

“…Another example is related to erosion models, which commonly employ 30-min timescale precipitation data. The rainfall intensity classes were defined based on their exceedance curves, following the recommendations of [26]. For both study areas, Zhurucay and Quinuas, the categories of 0-1, 1-2, 2-5, and 5-10 mm·h −1 were defined.…”

Measure of rainfall time structure using the dimensionless n-index

“…Precipitation accumulation is relatively well measured by rain gauges, but instantaneous rain rate is very difficult to measure with high precision, even using pluviographs or disdrometers (Liu et al 2013). Averaged intensities strongly depend on averaging time and rainfall time structure, which differs according to the natural processes that caused it.…”

Analysis of the Effects of Rainfall Intensity into the Performance of Video Conferencing

“…RD-80 measures the drop size using a Styrofoam cone with a sampling cross-sectional area of 50 cm 2 and has the ability to transform the vertical momentum of the drops to an electrical signal whose amplitude is a function of the drop diameter [16].…”