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Disdrometer

About: Disdrometer is a research topic. Over the lifetime, 930 publications have been published within this topic receiving 23092 citations.


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Journal ArticleDOI
TL;DR: In this article, the size spectra of oscillating raindrops were determined from photographic measurements in Illinois showers at night using strobe lights, and the oscillations were detected from modulations in the fall streaks produced by backscattered light near the primary rainbow.
Abstract: The size spectra of oscillating raindrops were determined from photographic measurements in Illinois showers at night. The oscillations were detected from modulations in the fall streaks produced by backscattered light near the primary rainbow. Drop sizes were determined from the fall speed using strobe lights. A continuous record of raindrop size distributions was obtained from a disdrometer located beneath the camera sample volume. Results show that oscillations begin near 1-mm diameter, at the onset size for vortex shedding. This finding is consistent with the authors' recent laboratory and field studies for small raindrops. The size spectra show that all raindrops above 1 mm are oscillating, out to the largest size measured of 4.2-mm diameter. Extrinsic sources of drop oscillations were evaluated using a collision model with viscous decay and using the pressure forcing from turbulence and wind shear in the surface layer. Based on the disdrometer size distributions, the number of oscillating d...

66 citations

Journal ArticleDOI
TL;DR: In this article, a technique for separating stratiform and convective rain types using the characteristics of two of the main drop size distribution (DSD) parameters is presented, which was originally developed based on observations from dual-frequency profiler and dual-polarization radar observations in Darwin, Australia.

65 citations

Journal ArticleDOI
TL;DR: In this paper, four different calibration methods were used to assess the drop size distribution: (1) Indication Paper, (2) Plaster Micro Plot, (3) Joss-Waldvogel Disdrometer and (4) Laser Distrometer (Thies).
Abstract: Rainfall simulation is a widely used method for soil erosion studies on agricultural land. Major problem of this experimental research method is the comparability between different simulators due to differences in simulated rainfall. Therefore the purpose of this study is to characterize the rainfall produced by a rainfall simulator which was widely used during the last decades. Four different calibration methods were used to assess the drop size distribution: (1) Indication Paper, (2) Plaster Micro Plot, (3) Joss–Waldvogel Disdrometer and (4) Laser Distrometer (Thies). Additionally, the latter one was used to measure drop fall velocity in combination with drop diameter. The spatial rainfall distribution pattern on the plot was measured with 100 rainfall gauges. The spatial rainfall distribution pattern clearly shows a heterogeneity, which is caused by the used nozzle configuration. Considerable differences in drop-size distribution can be observed depending on the used measurement technique. Laser Disdrometer and Plaster Micro Plot cover the whole produced drop size spectrum ranging from 3.0 mm, whereas Indication Paper as well as the Joss–Waldvogel Disdrometer primarily show drops smaller than 2.0 mm. Characterisation of rainfall is therefore strongly dependent on the used method and if different methods are used, may lead to contradictory results. The volume drop size distribution reflected by the Laser Distrometer is very similar to that one produced by rain with an intensity of 40 mm h −1 . Nevertheless, with maximum velocities above 10 m s −1 small drops are by far too fast and large drops with velocities dominantly below 5 m s −1 are too slow compared to natural rainfall. As an overall result, the simulator can be characterised as suitable for runoff and infiltration measurements, but with constraints due to the low reproducibility of the spatial rain distribution. As a consequence of the produced drop spectrum and fall velocity the erosion quantities may be underestimated systematically. For this, methodological development has to be focussed on homogeneous spatial rainfall distributions and on increasing the amount of large drops with higher fall velocities.

64 citations

Journal ArticleDOI
TL;DR: In this paper, six different types of automatic rain gauge systems have been collected for a set of summertime subtropical rain events at the University of South Florida and for a wintertime rain event at Miami, Florida.
Abstract: Automatic rain gauge systems are required to collect rainfall data at remote locations, especially oceanic sites where logistics prevent regular visits. Rainfall data from six different types of automatic rain gauge systems have been collected for a set of summertime subtropical rain events and for a set of wintertime rain events at Miami, Florida. The rain gauge systems include three types of collection gauges: weighing, capacitance, and tipping bucket; two gauges that inherently measure rainfall rate: optical scintillation and underwater acoustical inversion; and one gauge that detects individual raindrops: the disdrometer. All of these measurement techniques perform well; that is, they produce rainfall estimates that are highly correlated to one another. However, each method has limitations. The collection gauges are affected by flow irregularities between the catchment basin and the measurement chambers. This affects the accuracy of rainfall-rate measurements from these instruments, especiall...

64 citations

Journal ArticleDOI
TL;DR: In this paper, a modified version of the ZPHI algorithm is used to estimate the backscatter differential phase d and differential reflectivity ZDR in pure rain and in the melting layer.
Abstract: On the basis of simulations and observations made with polarimetric radars operating at X, C, and S bands, the backscatter differential phase d has been explored; d has been identified as an important polarimetric variable that should not be ignored in precipitation estimations that are based on specific differential phase KDP, especially at shorter radar wavelengths. Moreover, d bears important information about the dominant size of raindrops and wet snowflakes in the melting layer. New methods for estimating d in rain and in the melting layer are suggested.The method for estimatingdin rain is based on a modifiedversion of the ‘‘ZPHI’’ algorithm and provides reasonably robust estimates of d and KDP in pure rain except in regions where the total measured differential phase FDP behaves erratically, such as areas affected by nonuniform beam filling or low signal-to-noise ratio. The method for estimating d in the melting layer results in reliable estimates of d in stratiform precipitation and requires azimuthal averaging of radial profiles of FDP at high antenna elevations. Comparisons with large disdrometer datasets collected in Oklahoma and Germany confirm a strong interdependence between d and differential reflectivity ZDR. Because d is immune to attenuation, partial beam blockage, and radar miscalibration, the strong correlation between ZDR and d is of interest for quantitative precipitation estimation:dandZDRare differently affected by the particle size distribution(PSD) and thus may complement each other for PSD moment estimation. Furthermore, the magnitude of d can be utilized as an important calibration parameter for improving microphysical models of the melting layer.

64 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202378
2022114
202151
202059
201972
201840