Relevant bibliographies by topics / Disdrometer

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Academic literature on the topic 'Disdrometer'

Author: Grafiati
Published: 4 June 2021
Last updated: 8 February 2022

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Journal articles on the topic "Disdrometer"

1

Tokay, Ali, Paul G. Bashor, and Katherine R. Wolff. "Error Characteristics of Rainfall Measurements by Collocated Joss–Waldvogel Disdrometers." Journal of Atmospheric and Oceanic Technology 22, no. 5 (May 1, 2005): 513–27. http://dx.doi.org/10.1175/jtech1734.1.

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Abstract Error characteristics of rainfall measurements were studied using six collocated Joss–Waldvogel (JW) disdrometers that are located at NASA’s Wallops Flight Facility. The six disdrometer means of rain rate R, reflectivity Z, and differential reflectivity ZDR, for a given minute were considered as a reference. The maximum deviations of R, Z, and ZDR from the mean in a rain event were 0.6 mm h−1, 1.3 dB, and 0.05 dB, respectively. Rainfall statistics were then examined between disdrometer pairs. The root-mean-square (rms) difference of R, Z, and ZDR between paired disdrometers in a rain event were as high as 3.2 mm h−1, 3.7 dB, and 0.3 dB, respectively. The rms difference of R and ZDR were even higher when the disdrometer observations were stratified based on reflectivity intervals. The differences in disdrometer rainfall measurements have a potential impact when the disdrometers are considered as calibration tools for vertically pointing and scanning radars. The differences between the disdrometer measurements also result in differences in coefficients and exponents of the derived relations between radar parameters and rain rate. Among the four different relations between radar parameters and rain rate, the absolute difference in rain rate |ΔR| from two different JW disdrometers was highest in R(ZH, ZDR) and lowest in R(KDP, ZDR). The other two relations were R(Z) and R(KDP). The |ΔR| increases with increasing horizontally polarized reflectivity ZH, and differential specific phase KDP in both single- and dual-parameter rainfall estimators, while the |ΔR| increases with decreasing ZDR in dual-parameter rainfall estimators. Several sources of JW disdrometer malfunctions were also presented. The hardware problems were the leading cause for the malfunction of the JW disdrometers, as identified by the manufacturer. A single JW disdrometer could have inherent measurement errors that can only be identified in the presence of collocated (preferably two) rain-measuring instruments.
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Adirosi, Elisa, Nicoletta Roberto, Mario Montopoli, Eugenio Gorgucci, and Luca Baldini. "Influence of Disdrometer Type on Weather Radar Algorithms from Measured DSD: Application to Italian Climatology." Atmosphere 9, no. 9 (September 18, 2018): 360. http://dx.doi.org/10.3390/atmos9090360.

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Relations for retrieving precipitation and attenuation information from radar measurements play a key role in radar meteorology. The uncertainty in such relations highly affects the precipitation and attenuation estimates. Weather radar algorithms are often derived by applying regression methods to precipitation measurements and radar observables simulated from datasets of drop size distributions (DSD) using microphysical and electromagnetic assumptions. DSD datasets can be derived from theoretical considerations or obtained from experimental measurements collected throughout the years by disdrometers. Although the relations obtained from experimental disdrometer datasets can be generally considered more representative of a specific climatology, the measuring errors, which depend on the specific type of disdrometer used, introduce an element of uncertainty to the final retrieval algorithms. Eventually, data quality checks and filtering procedures applied to disdrometer measurements play an important role. In this study, we pursue two main goals: (i) evaluate two different techniques for establishing weather radar algorithms from measured DSD, and (ii) investigate to what extent dual-polarization radar algorithms derived from experimental DSD datasets are influenced by the different error structures introduced by the various disdrometer types (namely 2D video disdrometer, first and second generation of OTT Parsivel disdrometer, and Thies Clima disdrometer) used to collect the data. Furthermore, weather radar algorithms optimized for Italian climatology are presented and discussed.
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Raupach, T. H., and A. Berne. "Correction of raindrop size distributions measured by Parsivel disdrometers, using a two-dimensional video disdrometer as a reference." Atmospheric Measurement Techniques 8, no. 1 (January 16, 2015): 343–65. http://dx.doi.org/10.5194/amt-8-343-2015.

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Abstract. The raindrop size distribution (DSD) quantifies the microstructure of rainfall and is critical to studying precipitation processes. We present a method to improve the accuracy of DSD measurements from Parsivel (particle size and velocity) disdrometers, using a two-dimensional video disdrometer (2DVD) as a reference instrument. Parsivel disdrometers bin raindrops into velocity and equivolume diameter classes, but may misestimate the number of drops per class. In our correction method, drop velocities are corrected with reference to theoretical models of terminal drop velocity. We define a filter for raw disdrometer measurements to remove particles that are unlikely to be plausible raindrops. Drop concentrations are corrected such that on average the Parsivel concentrations match those recorded by a 2DVD. The correction can be trained on and applied to data from both generations of OTT Parsivel disdrometers, and indeed any disdrometer in general. The method was applied to data collected during field campaigns in Mediterranean France for a network of first- and second-generation Parsivel disdrometers, and on a first-generation Parsivel in Payerne, Switzerland. We compared the moments of the resulting DSDs to those of a collocated 2DVD, and the resulting DSD-derived rain rates to collocated rain gauges. The correction improved the accuracy of the moments of the Parsivel DSDs, and in the majority of cases the rain rate match with collocated rain gauges was improved. In addition, the correction was shown to be similar for two different climatologies, suggesting its general applicability.
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Tokay, Ali, and Paul G. Bashor. "An Experimental Study of Small-Scale Variability of Raindrop Size Distribution." Journal of Applied Meteorology and Climatology 49, no. 11 (November 1, 2010): 2348–65. http://dx.doi.org/10.1175/2010jamc2269.1.

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Abstract An experimental study of small-scale variability of raindrop size distributions (DSDs) has been carried out at Wallops Island, Virginia. Three Joss–Waldvogel disdrometers were operated at a distance of 0.65, 1.05, and 1.70 km in a nearly straight line. The main purpose of the study was to examine the variability of DSDs and its integral parameters of liquid water content, rainfall, and reflectivity within a 2-km array: a typical size of Cartesian radar pixel. The composite DSD of rain events showed very good agreement among the disdrometers except where there were noticeable differences in midsize and large drops in a few events. For consideration of partial beam filling where the radar pixel was not completely covered by rain, a single disdrometer reported just over 10% more rainy minutes than the rainy minutes when all three disdrometers reported rainfall. Similarly two out of three disdrometers reported 5% more rainy minutes than when all three were reporting rainfall. These percentages were based on a 1-min average, and were less for longer averaging periods. Considering only the minutes when all three disdrometers were reporting rainfall, just over one quarter of the observations showed an increase in the difference in rainfall with distance. This finding was based on a 15-min average and was even less for shorter averaging periods. The probability and cumulative distributions of a gamma-fitted DSD and integral rain parameters between the three disdrometers had a very good agreement and no major variability. This was mainly due to the high percentage of light stratiform rain and to the number of storms that traveled along the track of the disdrometers. At a fixed time step, however, both DSDs and integral rain parameters showed substantial variability. The standard deviation (SD) of rain rate was near 3 mm h−1, while the SD of reflectivity exceeded 3 dBZ at the longest separation distance. These standard deviations were at 6-min average and were higher at shorter averaging periods. The correlations decreased with increasing separation distance. For rain rate, the correlations were higher than previous gauge-based studies. This was attributed to the differences in data processing and the difference in rainfall characteristics in different climate regions. It was also considered that the gauge sampling errors could be a factor. In this regard, gauge measurements were simulated employing existing disdrometer dataset. While a difference was noticed in cumulative distribution of rain occurrence between the simulated gauge and disdrometer observations, the correlations in simulated gauge measurements did not differ from the disdrometer measurements.
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Raupach, T. H., and A. Berne. "Correction of raindrop size distributions measured by Parsivel disdrometers, using a two-dimensional-video-disdrometer as a reference." Atmospheric Measurement Techniques Discussions 7, no. 8 (August 19, 2014): 8521–79. http://dx.doi.org/10.5194/amtd-7-8521-2014.

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Abstract. The raindrop size distribution (DSD) quantifies the micro-structure of rainfall and is critical to studying precipitation processes. We present a method to improve the accuracy of DSD measurements from Parsivel disdrometers, using a two-dimensional-video-disdrometer (2DVD) as a reference instrument. Parsivel disdrometers bin recorded raindrops into velocity and equivolume diameter classes, but may mis-estimate the number of drops per class. We define a filter for raw disdrometer measurements to remove particles that are unlikely to be plausible raindrops. In our correction method, drop velocities are corrected with reference to theoretical models of terminal drop velocity. Non-plausible measurements are removed. Lastly, drop concentrations are corrected such that on average the Parsivel concentrations match those recorded by a 2DVD. The correction can be trained on and applied to data from both generations of Parsivel disdrometers. The method was applied to data collected during field campaigns in Mediterranean France, for a network of first and second generation Parsivel disdrometers. We compared the moments of the resulting DSDs to those of a collocated 2DVD, and the resulting DSD-derived rain rates to collocated rain gauges. The correction vastly improved the accuracy of the moments of the Parsivel DSDs, and in the majority of cases the rain rate match with collocated rain gauges was improved.
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Lewandowski, Piotr A., William E. Eichinger, Anton Kruger, and Witold F. Krajewski. "Lidar-Based Estimation of Small-Scale Rainfall: Empirical Evidence." Journal of Atmospheric and Oceanic Technology 26, no. 3 (March 1, 2009): 656–64. http://dx.doi.org/10.1175/2008jtecha1122.1.

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Abstract A significant scale gap between radar and in situ measurements of rainfall using rain gauges and disdrometers indicates a pressing need for improved knowledge of rainfall variability at the spatial scales below those of today’s operational radar rainfall products, that is, ∼1–4 km. Lidar technology has the potential to fulfill this need, but there has been inconsistency in the literature pertaining to quantitative observations of rain using lidar. Several publications have stated that light scattering properties of raindrops could not be correlated with rain rates, while other papers have demonstrated the existence of such relationships. This note provides empirical evidence in support of the latter claim. The authors conducted a simple experiment using a near-horizontal-pointing elastic lidar to observe rain in Iowa City, Iowa, in the fall of 2005. The lidar signal was used to estimate rainfall quantities that were subsequently compared with independent estimates of the same quantities obtained from an optical disdrometer that was placed about 370 m from the lidar, ∼10 m below the lidar beam. To perform the conversion from the raw lidar signal, the authors used an optical geometry-based procedure to estimate optical extinction data. A theoretical relationship between extinction coefficients and rain rates was derived based on a theoretical drop size distribution. The parameters of the relationship were found through a best-fit procedure using lidar and disdrometer data. The results show that the lidar-derived rain rates correspond to those obtained from the optical disdrometer with a root-mean-square difference of 55%. The authors conclude that although a great deal remains to be done to improve the inversion algorithm, lidar measurements of rain are possible and warrant further studies. Lidars deployed in conjunction with disdrometers can provide high spatial (<5 m) and temporal (<1 min disdrometer, ∼1 s lidar) resolution data over a relatively long distance for rainfall measurements (1–2 km in the case of the University of Iowa lidar).
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Johannsen, Lisbeth Lolk, Nives Zambon, Peter Strauss, Tomas Dostal, Martin Neumann, David Zumr, Thomas A. Cochrane, and Andreas Klik. "Impact of Disdrometer Types on Rainfall Erosivity Estimation." Water 12, no. 4 (March 28, 2020): 963. http://dx.doi.org/10.3390/w12040963.

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Soil erosion by water is affected by the rainfall erosivity, which controls the initial detachment and mobilization of soil particles. Rainfall erosivity is expressed through the rainfall intensity (I) and the rainfall kinetic energy (KE). KE–I relationships are an important tool for rainfall erosivity estimation, when direct measurement of KE is not possible. However, the rainfall erosivity estimation varies depending on the chosen KE–I relationship, as the development of KE–I relationships is affected by the measurement method, geographical rainfall patterns and data handling. This study investigated how the development of KE–I relationships and rainfall erosivity estimation is affected by the use of different disdrometer types. Rainfall data were collected in 1-min intervals from six optical disdrometers at three measurement sites in Austria, one site in Czech Republic and one site in New Zealand. The disdrometers included two disdrometers of each of the following types: the PWS100 Present Weather Sensor from Campbell Scientific, the Laser Precipitation Monitor from Thies Clima and the first generation Parsivel from OTT Hydromet. The fit of KE–I relationships from the literature varied among disdrometers and sites. Drop size and velocity distributions and developed KE–I relationships were device-specific and showed similarities for disdrometers of the same type across measurement sites. This hindered direct comparison of results from different types of disdrometers, even when placed at the same site. Thus, to discern spatial differences in rainfall characteristics the same type of measurement instrument should be used.
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Gires, Auguste, Philippe Bruley, Anne Ruas, Daniel Schertzer, and Ioulia Tchiguirinskaia. "Disdrometer measurements under Sense-City rainfall simulator." Earth System Science Data 12, no. 2 (April 14, 2020): 835–45. http://dx.doi.org/10.5194/essd-12-835-2020.

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Abstract. The Hydrology, Meteorology and Complexity Laboratory of École des Ponts ParisTech (http://hmco.enpc.fr, last access: 24 March 2020) and the Sense-City consortium (http://sense-city.ifsttar.fr/, last access: 24 March 2020) made available a dataset of optical disdrometer measurements stemming from a campaign that took place in September 2017 under the rainfall simulator of the Sense-City climatic chamber, which is located near Paris. Two OTT Parsivel2 disdrometers were used. The size and velocity of drops falling through the sampling area of the devices of roughly a few tens of square centimetres are computed by disdrometers. This enables the estimation of the drop size distribution and the further study of rainfall microphysics or kinetic energy for example. Raw data – basically a matrix containing a number of drops according to classes of size and velocity, along with more aggregated ones such as rain rate and drop size distribution with filtering – are available. The dataset is publicly available at https://doi.org/10.5281/zenodo.3347051(Gires et al., 2019).
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Adirosi, Elisa, Eugenio Gorgucci, Luca Baldini, and Ali Tokay. "Evaluation of Gamma Raindrop Size Distribution Assumption through Comparison of Rain Rates of Measured and Radar-Equivalent Gamma DSD." Journal of Applied Meteorology and Climatology 53, no. 6 (June 2014): 1618–35. http://dx.doi.org/10.1175/jamc-d-13-0150.1.

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AbstractTo date, one of the most widely used parametric forms for modeling raindrop size distribution (DSD) is the three-parameter gamma. The aim of this paper is to analyze the error of assuming such parametric form to model the natural DSDs. To achieve this goal, a methodology is set up to compare the rain rate obtained from a disdrometer-measured drop size distribution with the rain rate of a gamma drop size distribution that produces the same triplets of dual-polarization radar measurements, namely reflectivity factor, differential reflectivity, and specific differential phase shift. In such a way, any differences between the values of the two rain rates will provide information about how well the gamma distribution fits the measured precipitation. The difference between rain rates is analyzed in terms of normalized standard error and normalized bias using different radar frequencies, drop shape–size relations, and disdrometer integration time. The study is performed using four datasets of DSDs collected by two-dimensional video disdrometers deployed in Huntsville (Alabama) and in three different prelaunch campaigns of the NASA–Japan Aerospace Exploration Agency (JAXA) Global Precipitation Measurement (GPM) ground validation program including the Hydrological Cycle in Mediterranean Experiment (HyMeX) special observation period (SOP) 1 field campaign in Rome. The results show that differences in rain rates of the disdrometer DSD and the gamma DSD determining the same dual-polarization radar measurements exist and exceed those related to the methodology itself and to the disdrometer sampling error, supporting the finding that there is an error associated with the gamma DSD assumption.
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Frech, Michael, Martin Hagen, and Theo Mammen. "Monitoring the Absolute Calibration of a Polarimetric Weather Radar." Journal of Atmospheric and Oceanic Technology 34, no. 3 (March 2017): 599–615. http://dx.doi.org/10.1175/jtech-d-16-0076.1.

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AbstractThe absolute calibration of a dual-polarization radar of the German Weather Service is continuously monitored using the operational birdbath scan and collocated disdrometer measurements at the Hohenpeissenberg observatory. The goal is to measure the radar reflectivity constant Z better than ±1 dB. The assumption is that a disdrometer measurement close to the surface can be related to the radar measurement at the first far-field range bin. This is verified using a Micro Rain Radar (MRR). The MRR data fill the gap between the measurement near the surface and the far-field range bin at 650 m. Using data from the first half of the warm season in 2014, a bias in radar calibration of 1.8 dB is found. Data from only stratiform precipitation events are considered. After adjusting the radar calibration and using an independent data sample, very good agreement is found between the radar, the MRR, and the disdrometer with a bias in smaller than 1 dB. The bias in is not captured with the classic one-point calibration, which is performed twice a day using a built-in test signal generator. This is attributed to the fact that the characterization of the transmit and receive path is not accurate enough. Solar interferences during the operational scanning are used to characterize the receiver. There, the bias found is small, about 0.2 dB, so that bias based on the comparison of the radar with external sensors is attributed to the transmit path. The representativeness of the disdrometer measurements are assessed using two additional disdrometers located within 200-m distance.
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Dissertations / Theses on the topic "Disdrometer"

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Winder, Philip Newton. "An acoustic water tank disdrometer." Thesis, University of Hull, 2010. http://hydra.hull.ac.uk/resources/hull:3469.

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Microwave engineers and geomorphologists require rainfall data with a much greater temporal resolution and a better representation of the numbers of large raindrops than is available from current commercial instruments. This thesis describes the development of an acoustic instrument that determines rain parameters from the sound of raindrops falling into a tank of water. It is known as the acoustic water tank disdrometer (AWTD).There is a direct relationship between the kinetic energy of a raindrop and the acoustic energy generated upon impact. Rain kinetic energy flux density (KE) is estimated from measurements of the sound field in the tank and these have been compared to measurements from a co-sited commercial disdrometer.Furthermore, using an array of hydrophones it is possible to determine the drop size and impact position of each raindrop falling into the tank. Accumulating the information from many impacts allows a drop size distribution (DSD) to be calculated.Eight months of data have been collected in the eastern UK. The two methods of parameter estimation are developed and analysed to show that the acoustic instrument can produce rain KE measurements with a one-second integration times and DSDs with accurate large drop-size tails.
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Thomson, Alan D. "Precipitation processes as deduced by combining Doppler radar and disdrometer." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ28306.pdf.

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Brugman, Karen Elizabeth. "Variations in storm structure and precipitation characteristics associated with the degree of environmental baroclinicity in Southeast Texas." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1894.

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Brawn, Dan R. "An elementary estimation of gamma parameters and the analysis of disdrometer data." Thesis, University of Essex, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496248.

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This thesis considers the problem of estimating the three parameters of a gamma distribution with grouped and truncated data. Sample sizes may be small and commonly subject to lower and perhaps upper truncation. A new simple, closed form, rehable. almost unbiased and low-variance method is developed. It is shown that the new 'hybrid' approach is a first order approximation to maximum like.hood with a constraint that incorporates a single sample moment ratio. Traditional moment methods require three distinct sample moments and typically give ised estimates. The operation of the hybrid method is discussed and extended to encompass the estimation of parameters for a Generalized Gamma mode.
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Aiazzi, Lorenzo. "Combined analysis of C-band polarimetric radar and disdrometer data of convective and stratiform precipitation." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22121/.

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The aim of the present Thesis is to observe the characteristics of the precipitation and to check the quality of the radar data under different meteorological conditions. This aim is achieved through a combined analysis of the data collected by two instruments that have different operating principles: a C-band polarimetric radar and a PARSIVEL2 disdrometer. Radar variables are compared with the characteristics and the microphysics evolution of the precipitation retrieved by the disdrometer. The disdrometer is located in the city center of Bologna, at about 28 km far from the radar site. The combined analysis of the two instruments is done for a dataset that includes 11 months of the years 2019 and 2020. The dataset contains convective and stratiform precipitation events. The lower radar elevations are affected by anthropogenic interferences that slightly reduce the dataset extension. The analyses show a good correlation between the reflectivity factors retrieved by the radar and by the disdrometer through the Drop Size Distribution (DSD). The correlation coefficient between the two estimations is 0.84. A verification of the operational algorithm of the hydrometeor classification is obtained through the radar data. Moreover, the convective and stratiform discrimination developed through the disdrometer data is consistent with the polarimetric variables of the radar. For example, the distribution of the differential reflectivity peaks for higher values in a regime of convective precipitation in comparison to the stratiform regime. The convective distribution of the differential reflectivity has a median of 1.5 dB, while the stratiform one has a median of 0.9 dB. Lastly, the case study of a thunderstorm occurred in Bologna on May 28th 2019 is described. This case study shows precipitation structures of different intensities and different types of hydrometeors, allowing a verification of the previous results and a more-detailed analysis of the DSD characteristics.
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Winsky, Bryson Evan. "A redesigned instrument and new data analysis method used to measure the size and velocity of hydrometeors." Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/3406.

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Wennerdahl, Emelie. "Utvärdering av regnmätning och droppstorleksfördelning från en distrometer." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-256926.

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Nederbördsmätning är viktigt inom många områden och en relativt ny teknik är enoptisk distrometer som med hjälp av laserteknik mäter nederbördspartiklarnasdroppstorlek och fallhastighet. Syftet med detta arbete var att undersöka hur välThies distrometer stämmer överens med nederbördsmätning från ett vippkärl ochmanuella mätningar från institutionen för geovetenskaper vid Uppsala universitet.Institutionen för geovetenskaper överväger att gå över till denna teknik och därmedbehövdes distrometern utvärderas för olika faktorer som kan påverka instrumentet.Vid jämförelse mellan instrumenten visade det sig att distrometern totalt sett samladein mer nederbörd än de andra mätarna. Det är svårt att avgöra vad skillnaden mellaninstrumenten kan bero på men felkällor så som avdunstning och vätning hos vippkärletoch manuella mätningar kan ge mindre nederbörd. En annan orsak kan varafelkalibrering av datan från distrometern. Inga samband hittades för vindhastighet,vindriktning och typ av nederbörd mellan de tre instrumenten. En vidare undersökning gjordes för droppstorleksfördelningen för att ge exempelpå fördelar med en distrometer. Droppstorleksfördelningen från distrometernjämfördes med exponentialfördelningen framtagen av Marshall & Palmer (1948).Resultatet visade sig stämma överens med tidigare studier, fördelningen stämmerbra överens för stratiforma väder, men sämre för konvektiva och snö.
Measuring precipitation is important in many areas of research. A relatively newtechnology for measuring precipitation is the optical disdrometer, which measures thefalling velocity and drop size of particles by using lasers. The purpose of this workwas to compare data from a disdrometer with data from a tipping bucket and amanual measurement series from the Department of Earth Sciences at UppsalaUniversity. The comparison between the instruments showed that the disdrometermeasured more precipitation than the tipping bucket and the manual measurements.A reason for this can be due to evaporation and wetting from the tipping bucket andmanual measurement. Errors in calibration of data from the disdrometer may alsohave influence. Furthermore, an analysis of the drop size distribution was done in order todetermine areas of special use for the device. The drop size distribution calculatedfrom the distrometer was compared with the Marshall and Palmer (1948) distribution.The results showed that the MP-distribution was a good fit for stratiform weather;however, for convective clouds and snow the fit was not satisfactory and some otherrelationship should be used instead.
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Åsberg, Mathias. "Kvantifiering av simulerat regn i vindtunnel." Thesis, Mittuniversitetet, Avdelningen för kvalitets- och maskinteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-34788.

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Vindtunneln som drivs av Sports Tech Research Centres   är en unik anläggning för att bedriva forskning på både atletiska utövare och   utrustning. Vindtunnelns avancerade system möjliggör för forskning och tester   på material och produkter kan utföras i en verklighetstrogen miljö. Det finns   även sedan byggnationen ett regnsystem installerat i vindtunneln. Detta   system är inte uppmätt efter viktiga faktorer och ingen vetskap om det   simulerade regnets egenskaper eller likhet med naturligt förekommande regn   finns. Syftet med arbetet var att utföra mätningar på det   befintliga regnsystemet med avseende på storlek och fallhastighet för   dropparna. Arbetets syfte var även att jämföra de uppmätta regn egenskaperna   mot vetenskapliga modeller som beskriver ett naturligt regn. Där målet med   arbetet var att ta fram ett underlag på det befintliga regnet i vindtunneln. Testerna utfördes med en optisk distrometer som   mätte de fallande vattendropparna med en laser. Distrometern användes för att   mäta storlek samt fallhastighet på vattendropparna. Distrometer placerades   vid tester på olika höjder i vindtunneln, regnet undersöktes även vid   varierande vattenflöde och vindhastigheter. Resultatet visade på att simulerade regnet hade en   lägre hastighet i förhållande till den uppmätta droppstorleken högt i   tunneln. Hastigheten på dropparna lågt i tunneln visade mer följa modellernas   beskrivning av en naturligfallhastighet. Droppstorleksfördelningen visades   inte överstämma mot naturligt regn utan visar på en högre mängd stora droppar   än vad som är naturligt förekommande. Intensiteten i vindtunneln var som   lägst 62 mm/h vilket väldigt högt sett från naturligt regn. Utifrån dessa   parametrar följer inte det simulerade regnet ett naturligt förekommande regn.
The wind tunnel operated by Sport Tech Research Centres,   are a unique facility to conduct research on athletic practitioners and their   equipment. The advanced systems in the wind tunnel allows for research and   testing of materials and product in a realistic environment. Since the   construction of the wind tunnel a rain system was fitted. This system is not   measured for important factors and no knowledge of the simulated rainfall   properties or similarities to naturally occurring rain exists. The aim of this work was to perform measurements of   the existing rainfall system with regards to size and falls speed of the   droplets. The purpose was also to compare the measure rain properties to   scientific models describing natural rainfall. The goal of the work was to   get a foundation of the existing rain in the wind tunnel. The tests were performed with an optic disdrometer   that measured the falling water particles with a laser. The disdrometer   measured size and fall speed of the droplets. The tests were carried out on   different heights in the wind tunnel, the rain was also investigated at   varying water pressure and wind speeds. The result shows that the simulated rainfall had   lower speed relative to the measured drop size high in the tunnel. Fall speed   of droplets low in the tunnel showed more according to the model’s   description of a natural rain fall speed. Drop size distribution was shown   not to be consistent with natural rainfall. The distribution shows a higher   amount of large drops than is naturally occurring. Rainfall intensity was   measured to 62 mm/h as lowest which is very high compared to natural rain.   Based on these parameters the simulated rain is not a naturally occurring   rainfall.

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9

Bracci, Alessandro. "Analysis of precipitation from ground observations over the Antarctic coast." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16875/.

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The primary mass input of the Antarctic ice sheet is represented by snow precipitation. Despite of their crucial role, the estimates of precipitation over Antarctica are sparse and characterized by large uncertainties. Recently, the Italian Mario Zucchelli station (MZS) at Terra Nova Bay was equipped with instruments for monitoring precipitation. This thesis is part of the APP-PNRA project (Antarctic precipitation properties from ground-based instruments), whose object is to set up an observatory to characterize precipitation at MZS. The present study was focused on the evaluation of the response of solid hydrometeors to the electromagnetic radiation and on the microphysical characterization of precipitation. The former was investigated using a pre-computed discrete dipole approximation (DDA) database for complex-shape snowflakes and a T-Matrix code for soft-spheroids. The backscattering cross sections, calculated at the K-band by the two methods, were compared. In case of aggregate particles the methods show a poor agreement, comparable values were found when pristine crystals were considered. The latter was examined through in-situ observations by a Parsivel disdrometer and Micro Rain Radar. By exploiting the Parsivel data collected during the summer seasons 2016-17 and 2017-18, the particle size distributions (PSD) of hydrometeors were derived, showing a high number of particles with very small diameter. Numerical simulations, driven by DDA and T-Matrix, were also performed by using the PSDs, to obtain the simulated radar reflectivity. The comparative analysis of simulated and actual reflectivity allowed inferring microphysical characterization of precipitation. Based on this methodology, 16 out of 22 snow days were categorized: 6 as having aggregate-like features and 10 as pristine crystal-like. These results will be of practical interest, giving an important contribution toward a more accurate quantification of snow accumulation in Antarctica.
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10

Depuydt, Guillaume. "Etude expérimentale in situ du potentiel de lessivage de l'aérosol atmosphérique par les précipitations." Thesis, Toulouse, INPT, 2013. http://www.theses.fr/2013INPT0122/document.

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En cas de rejets de polluants ou de radionucléides dans l’atmosphère, l’estimation du lessivage des particules d’aérosol atmosphérique par les précipitations est une donnée essentielle pour évaluer la contamination de la biosphère. De nombreuses études se sont déjà intéressées à ce processus de dépôt humide, mais la plupart d’entre elles sont d’ordre théoriques ou ont été menées en laboratoire. Cette étude a donc pour objectif d’améliorer la connaissance du potentiel de lessivage des particules d’aérosol par les précipitations par une approche expérimentale en conditions in situ. Durant plusieurs mois, trois sites aux environnements distincts en termes de climatologie et d’empoussièrement ambiant ont été instrumentés pour disposer d’une palette de situations précipitations/empoussièrement la plus variée possible. Un disdromètre laser et un granulomètre (compteur électrique et/ou optique) ont mesurés respectivement les caractéristiques des précipitations et les concentrations de particules à une résolution temporelle élevée et sur une large gamme de diamètre. L’utilisation de ce couplage instrumental original a permis de déterminer les potentiels de lessivage pour des particules de la gamme nanométrique à supermicronique et pour différents types de précipitations (chutes de neige et pluies avec des hyétogrammes spécifiques). Dans un premier temps, le coefficient de lessivage ᴧ (paramètre décrivant la cinétique du processus) a été calculé en considérant l’effet global d’une précipitation. Cette approche « macroscopique » est limitée par l’influence de processus « concurrents », tels que l’advection ou les sources d’émissions de particules à proximité des sites de mesures. Pour minimiser l’impact de ces processus sur nos résultats, une seconde méthodologie basée sur la résolution temporelle élevée de l’instrumentation utilisée a été définie. Par cette approche « intra-évènementielle », les coefficients de lessivage ᴧ sont calculés sur de courtes périodes de temps, permettant ainsi d’étudier l’influence de la variabilité du diamètre des particules et des caractéristiques des précipitations sur ces coefficients. Les résultats obtenus par les deux types d’approches ont mis en évidence la nécessité de prendre en compte le diamètre des particules et les caractéristiques des précipitations pour modéliser fidèlement le lessivage des particules d’aérosol atmosphérique. En comparant les résultats des deux types de précipitations, la prédominance du lessivage par des chutes de neige par rapport au lessivage par la pluie a été illustrée. L’importance du diamètre des particules lessivées a été démontrée. Entre le mode « ultrafin » et le mode « grossiers », la variation du coefficient de lessivage est d’un ordre de grandeur (entre environ 2.10¯³et 2.10¯⁴ s¯¹). Le potentiel de lessivage minimum est obtenu pour des particules d’environ 100 nm, ce qui est cohérent avec la théorie du « Greenfield gap » (entre 0,1 et 1 µm). Pour les besoins de la modélisation, une paramétrisation robuste entre le coefficient de lessivage ᴧ et le diamètre des particules d’aérosol (de 10 nm à 10 µm) a été établie. Différentes relations entre le coefficient ᴧ et l’intensité pluviométrique sont proposées aussi pour différentes gammes de diamètre de particules et comparées notamment aux valeurs implémentées actuellement dans le modèle ldX utilisé à l’Institut de Radioprotection et de Sûreté Nucléaire
In case of release of pollutant or radionuclides into the atmosphere, estimate of below-cloud scavenging of aerosol particles by precipitation (or washout) is an essential data to evaluate contamination of the biosphere. Many studies have already shown an interest to this wet deposition process, but most of them are theoretical or have been conducted in laboratories conditions. This study in situ conditions aims to improve knowledge of below-cloud scavenging of aerosol particles by precipitation. For several months, three sites with separate environments in terms of climate and ambient dust have been instrumented to have such a varied palette of precipitation/dust conditions as possible. A laser disdrometer and a granulomètre (electrical and/or optical counter) measure respectively precipitations characteristics and particles concentrations with a high temporal resolution (one minute). The use of this original instrumental coupling has allowed determining washout potentials for the nanometric size range of particles aerosol to the supermicronique size range and for different types of precipitation (snowfalls and rainfalls with specifics hyetograms).Initially, below-cloud scavenging coefficients ᴧ (parameter describing kinetic of this process) were calculated considering the gobal effet of a precipitation. This “macroscopic” approach is limited by the influence of “concurrent” processes, as advection or local emissions of aerosol particles close to the measurements sites. To minimise effect of these processes on our results, a second methodology based on the high temporal resolution of the instrumentation used was defined. With this “intra-event” approach, washout coefficients are calculated on short time scales, allowing study of impact of the variability of aerosol size and precipitations characteristics on these coefficients.Results obtained with the two approaches highlighted the need of considering particles diameter and characteristics of precipitation to model accurately below-cloud scavenging of aerosol particles. Comparing results for both type of precipitation, predomination of below-cloud scavenging by snowfalls compared with below-cloud scavenging by rainfalls was shown. The importance of the scavenged aerosol diameter was demonstrated. From the “ultrafine” size range to coarse mode of particles, below-cloud scavenging coefficient varies by an order of magnitude (from 2.10¯³ to 2.10¯⁴ s¯¹). Minimum potential is obtained for particles of about 100 nm, which is consistent with theory of “Greenfield gap” (from 0.1 to 1 µm). For modeling needs, a robust parametrization between washout coefficient ᴧ and aerosol particles diameter (from 10 nm to 10 µm) has been established. Also some relationships between coefficient ᴧ and rainfall intensity are proposed for different particles size range and compared in particular with values implemented in model ldX currently used at the French Institute of Radioprotection and Nuclear Safety
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Books on the topic "Disdrometer"

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A, Nystuen Jeffrey, and Atlantic Oceanographic and Meteorological Laboratories, eds. APL disdrometer evaluation. Miami, Fla: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Environmental Research Laboratories, Atlantic Oceanographic and Meteorological Laboratory, 1994.

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Thomson, Alan D. Precipitation processes as deduced by combining doppler radar and disdrometer. 1997.

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Book chapters on the topic "Disdrometer"

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Montopoli, Mario, and Frank S. Marzano. "An Introduction to Rain Gauges and Disdrometers." In Integrated Ground-Based Observing Systems, 107–14. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12968-1_5.

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Willems, Patrick, and Thomas Einfalt. "Sensors for rain measurements." In Metrology in Urban Drainage and Stormwater Management: Plug and Pray, 11–33. IWA Publishing, 2021. http://dx.doi.org/10.2166/9781789060119_0011.

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Abstract Rain measurements based on rain gauges, disdrometers, weather radars and microwave links provide essential input data for urban drainage and stormwater modelling, management, and planning. Their quality strongly depends on the sensor type and calibration, but also on the data post-processing that includes quality control and data adjustment after comparison with reference observations. This chapter provides an overview of traditional techniques and recent developments, and practical advice on the selection of the type of instrument, the installation and calibration aspects to be considered, and the measurement data processing and adjustment needs.
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Conference papers on the topic "Disdrometer"

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Van Quyen, Lai Thi, Nguyen Manh Thang, Nguyen Hong Vu, Nguyen The Truyen, Dmitry Kiesewetter, and Victor Malyugin. "The Optical Disdrometer." In 2017 Advances in Wireless and Optical Communications (RTUWO). IEEE, 2017. http://dx.doi.org/10.1109/rtuwo.2017.8228499.

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Berthoud, Alain, Samuel Burri, Claudio Bruschini, Alexis Berne, and Edoardo Charbon. "A Disdrometer based on ultra-fast SPAD Cameras." In Imaging Systems and Applications. Washington, D.C.: OSA, 2011. http://dx.doi.org/10.1364/isa.2011.ima2.

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Pangaliman, Ma Madecheen S., Febus Reidj G. Cruz, and Timothy M. Amado. "Machine Learning Predictive Models for Improved Acoustic Disdrometer." In 2018 IEEE 10th International Conference on Humanoid, Nanotechnology, Information Technology,Communication and Control, Environment and Management (HNICEM). IEEE, 2018. http://dx.doi.org/10.1109/hnicem.2018.8666256.

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Schönhuber, M., F. Cuervo, N. Knoll, and V. Mitterauer. "Reliability of Disdrometer-derived W-Band Attenuation Predictions." In 12th European Conference on Antennas and Propagation (EuCAP 2018). Institution of Engineering and Technology, 2018. http://dx.doi.org/10.1049/cp.2018.0624.

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Feloni, Elissavet, Evangelos Baltas, Konstantinos Kotsifakis, Nikolaos Dervos, and George Giavis. "Analysis of Joss-Waldvogel disdrometer measurements in rainfall events." In Fifth International Conference on Remote Sensing and Geoinformation of the Environment (RSCy2017), edited by Giorgos Papadavid, Diofantos G. Hadjimitsis, Silas Michaelides, Vincent Ambrosia, Kyriacos Themistocleous, and Gunter Schreier. SPIE, 2017. http://dx.doi.org/10.1117/12.2279610.

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Ibrahim, I. A., V. Chandrasekar, V. N. Bringi, P. C. Kennedy, M. Schoenhuber, H. E. Urban, and W. L. Randen. "Simultaneous multiparameter radar and 2D-video disdrometer observations of snow." In IGARSS '98. Sensing and Managing the Environment. 1998 IEEE International Geoscience and Remote Sensing. Symposium Proceedings. (Cat. No.98CH36174). IEEE, 1998. http://dx.doi.org/10.1109/igarss.1998.702931.

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Adirosi, E., L. Baldini, and A. Tokay. "Comaparison of Disdrometer Performance During GPM-GV IFloodS Field Campaign." In 2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC). IEEE, 2018. http://dx.doi.org/10.23919/ursi-at-rasc.2018.8471441.

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Cao, Q., G. Zhang, T. Schuur, A. Ryzhkov, E. Brandes, and K. Ikeda. "Characterization of Rain Microphysics based on Disdrometer and Polarimetric Radar Observations." In 2006 IEEE International Symposium on Geoscience and Remote Sensing. IEEE, 2006. http://dx.doi.org/10.1109/igarss.2006.139.

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Kasparis, Takis, John Lane, and Linwood Jones. "Modeling of an impact transducer for in situ adaptive disdrometer calibration." In 2010 4th International Symposium on Communications, Control and Signal Processing (ISCCSP). IEEE, 2010. http://dx.doi.org/10.1109/isccsp.2010.5463471.

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Cruz, Febus Reidj G., Ma Madecheen S. Pangaliman, Timothy M. Amado, and Francis Aldrine A. Uy. "Development of Improved Acoustic Disdrometer Through Utilization of Machine Learning Algorithm." In TENCON 2018 - 2018 IEEE Region 10 Conference. IEEE, 2018. http://dx.doi.org/10.1109/tencon.2018.8650318.

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Reports on the topic "Disdrometer"

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Hardin, Joseph, Scott Giangrande, and Aifang Zhou. Laser Disdrometer Quantities (LDQUANTS) and Video Disdrometer Quantities (VDISQUANTS) Value-Added Products Report. Office of Scientific and Technical Information (OSTI), April 2020. http://dx.doi.org/10.2172/1808573.

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Bartholomew. MJ. Disdrometer and Tipping Bucket Rain Gauge Handbook. Office of Scientific and Technical Information (OSTI), December 2009. http://dx.doi.org/10.2172/1019411.

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Kollias, Pavlos, and Mary Jane Bartholomew. Parsivel Disdrometer Support for MAGIC Field Campaign Report. Office of Scientific and Technical Information (OSTI), June 2016. http://dx.doi.org/10.2172/1255440.

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Bartholomew, Mary Jane. Impact Disdrometers Instrument Handbook. Office of Scientific and Technical Information (OSTI), March 2016. http://dx.doi.org/10.2172/1251384.

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