Microprocessor Field Impactometer Calibration: Do We Measure Drops’ Momentum or Their Kinetic Energy?

Licznar, P.; Łomotowski, Janusz; Błoński, Sławomir; Ciach, Grzegorz J.

doi:10.1175/2007jtecha938.1

Cited by 8 publications

(7 citation statements)

References 22 publications

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“…They measure the Doppler shift, which F I G U R E 1 5 Images captured by the high-speed camera used to estimate the drop velocity just before the impact. Source: Licznar et al (2008) F I G U R E 1 6 Image of the Styrofoam particles used by Bernauer et al (2015) to simulate solid precipitation depends on the component of velocity in the direction connecting the hydrometeor and the antenna phase centre, therefore the return signal is a function of both the horizontal and vertical velocity components. These instruments assume that the relative velocity is equal to the terminal velocity and then use an empiric relationship to derive the hydrometeor's diameter.…”

Section: Windmentioning

confidence: 99%

Calibration of non‐catching precipitation measurement instruments: A review

Lanza

Merlone

Cauteruccio

et al. 2021

Meteorological Applications

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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.

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Section: Windmentioning

confidence: 99%

Calibration of non‐catching precipitation measurement instruments: A review

Lanza

Merlone

Cauteruccio

et al. 2021

Meteorological Applications

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“…Optical disdrometers are relatively new instruments that have the potential to meet these requirements. Although the performance of impact disdrometers is well documented (Joss and Waldvogel, 1977;Kinnell, 1976;Licznar et al, 2008;Tokay et al, 2005;Tokay et al, 2001;Tokay et al, 2003), the error characteristics of their optical counterpart are not yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

Understanding the partitioning of rainfall by the maize canopy through computational modelling and physical measurements

Frasson¹

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The interception and redirection of rainfall by vegetation has implications for many fields such as remote sensing of soil moisture, satellite observation of rainfall, and the modeling of runoff, climate, and soil erosion. Although the modeling of rainfall partitioning by forests has received attention in the past, partitioning caused by crops has been overlooked. The present work proposes a two front experimental and computational methodology to comprehensively study rainfall interception and partitioning by the maize canopy.In the experimental stage, we deployed two compact weather stations, two optical disdrometers, and five tipping bucket rain gauges. Two of the tipping bucket rain gauges were modified to measure throughfall while two were adapted to measure stemflow. The first optical disdrometer allowed for inspection of the unmodified drop-size and velocity distributions, whereas the second disdrometer measured the corresponding distributions under the canopy. This indicates that the outcome of the interaction between the hydrometeors and the canopy depends on the drop diameter.In the computational stage, we created a model that uses drop-size and velocity distributions as well as a three-dimensional digital canopy to simulate the movement of raindrops on the surfaces of leaves. Our model considers interception, redirection, retention, coalescence, breakup, and re-interception of drops to calculate the stemflow, throughfall, and equivalent height of precipitation stored on plants for a given storm.Moreover, the throughfall results are presented as two-dimensional matrices, where each term corresponds to the accumulated volume of drops that dripped at a given location.This allows insight into the spatial distribution of throughfall beneath the foliage. Finally, we examine the way in which the maize canopy modifies the drop-size distribution by recalculating the drop velocity based on the raindrop's size and 2011 All Rights Reserved Graduate College ii To my parents Mirian and Deodoro Frasson and my lovely wife iii ACKNOWLEDGMENTS During my studies at The University of Iowa, I have worked with an amazing array of people, from whom I have learned a wide variety of professional and interpersonal skills. I would like to begin by acknowledging the support, encouragement, and guidance of Professor Witold Krajewski, who made this thesis possible. In addition to the scientific skills that Professor Krajewski taught me, he showed me how to balance my professional and personal lives, how to focus on a task and see it to fruition, and how to maintain sight of where my work fits into the big picture. He improved my ability to present my work and taught me the difference between a poster and a paper.

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“…A HSC has been used to investigate the behavior of raindrop oscillations and the impact of water drops on the Earth's surface, as described in a number of articles (Fukada and Fujiwara, 1989;Ghadiri, 2006;Testik et al, 2006;Licznar et al, 2008;Szakáll et al, 2010). However, these HSC published works did not address the possible application of the HSC to the investigation of atmospheric DFSs.…”

Section: Introductionmentioning

confidence: 99%

Measuring droplet fall speed with a high-speed camera: indoor accuracy and potential outdoor applications

Hsieh

Yuter

et al. 2016

Atmos. Meas. Tech.

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Abstract. Acquisition of accurate raindrop fall speed measurements outdoors in natural rain by means of moderatecost and easy-to-use devices represents a long-standing and challenging issue in the meteorological community. Feasibility experiments were conducted to evaluate the indoor accuracy of fall speed measurements made with a high-speed camera and to evaluate its capability for outdoor applications. An indoor experiment operating in calm conditions showed that the high-speed imaging technique can provide fall speed measurements with a mean error of 4.1-9.7 % compared to Gunn and Kinzer's empirical fall-speed-size relationship for typical sizes of rain and drizzle drops. Results obtained using the same apparatus outside in summer afternoon showers indicated larger positive and negative velocity deviations compared to the indoor measurements. These observed deviations suggest that ambient flow and turbulence play a role in modifying drop fall speeds which can be quantified with future outdoor high-speed camera measurements. Because the fall speed measurements, as presented in this article, are analyzed on the basis of tracking individual, specific raindrops, sampling uncertainties commonly found in the widely adopted optical disdrometers can be significantly mitigated.

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Microprocessor Field Impactometer Calibration: Do We Measure Drops’ Momentum or Their Kinetic Energy?

Cited by 8 publications

References 22 publications

Calibration of non‐catching precipitation measurement instruments: A review

Calibration of non‐catching precipitation measurement instruments: A review

Understanding the partitioning of rainfall by the maize canopy through computational modelling and physical measurements

Measuring droplet fall speed with a high-speed camera: indoor accuracy and potential outdoor applications

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