Disdrometer

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

Long‐Term Rain Attenuation Measurement for Short‐Range mmWave Fixed Link Using DSD and ITU‐R Prediction Models

Abstract: Several millimeter Wave (mmWave) bands, which suffer from rain attenuation, were identified in the World Radiocommunication Conference 2019 (WRC-19) for fifth generation (5G) radio networks. In this paper, long-term attenuation is measured over typical building to building radio links in the built environment, which constitute two 36 m links along a direct link and an indirect side link at 25.84 and 77.54 GHz and a 200 m link at 77.125 GHz. The attenuation was also estimated using precipitation data from a high end accurate disdrometer weather station using the drop size distribution and the International Telecommunication Union (ITU) models. The results indicate that attenuation using Mie theory is in agreement with the ITU model for most of the rainfall events; with higher attenuation being measured than predicted when snow grains and raindrops mix. Raindrops with diameter between 0.1 and 4 mm indicate that the dominant raindrops have considerable influence on the measured attenuation, especially at light and moderate rainfall events. The maximum distance factor restriction of 2.5 in ITU-R P.530-17 is shown not to be suitable for short-range fixed links as it excessively underestimates attenuation.

In situ disdrometer calibration using multiple DSD moments

Abstract: In situ calibration is a proposed strategy for continuous as well as initial calibration of an impact disdrometer. In previous work, a collocated tipping bucket had been utilized to provide a rainfall rate based ∼11/3 moment reference to an impact disdrometer’s signal processing system for implementation of adaptive calibration. Using rainfall rate only, transformation of impulse amplitude to a drop volume based on a simple power law was used to define an error surface in the model’s parameter space. By incorporating optical extinction second moment measurements with rainfall rate data, an improved in situ disdrometer calibration algorithm results due to utilization of multiple (two or more) independent moments of the drop size distribution in the error function definition. The resulting improvement in calibration performance can be quantified by detailed examination of the parameter space error surface using simulation as well as real data.

An Approach for the Estimation of Hydrometeorological Variables Towards the Determination of Z-R Coefficients

Abstract: An attempt is made to estimate the basic hydrometeorological variables, namely the rainfall concentration for each bin per m3, the radar reflectivity factor Z and the rainfall intensity R, and consequently to determine coefficient “a” and exponent “b” of the power law relationship Z = aRb. Data used were recorded in a period of almost 10 years, with a Joss-Walvogel RD-69 disdrometer (JWD), located in the meteorological station of the campus of National Technical University of Athens. A number of rainfall events were selected based on the following criteria: the total rainfall depth of each event was greater than 24.0 mm and the average rainfall intensity exceeded 5.0 mm/h, in order to only study events with increased flash flooding probability. Initially, Drop Size Distributions (DSDs) were calculated for these rainfall events and processed for the derivation of Z-R relationships. Such Z-R relationships were finally derived for the overall spectra of R > 5.0 mm/h and for each event separately and were compared with other Z-R relationships found in the literature.

Long Term Rain Attenuation Measurements at Millimeter Wave Bands for Direct and Side Short-Range Fixed Links

Abstract: Millimeter wave (mmWave) radio links are largely affected by precipitation. In this paper, we use a custom-designed continuous wave (CW) channel sounder to record channel data at K band (25.84 GHz) and E band (77.52 GHz) for direct line of sight link and a side non line of sight link with dual polarizations. A high-performance PWS100 disdrometer is utilized to collect weather data, including rain rate and rain drop size distribution (DSD) for rain attenuation study. The rain attenuation for both links are compared. The side link exhibits a slightly higher attenuation than the direct link. The ITU-R P.838-3 model and DSD model are applied to model the rain attenuation. The results will be useful for the design of fixed links for fifth generation (5G) mmWave communication systems.

A hail size distribution impact transducer

Abstract: An active impact transducer has been designed and tested for the purpose of monitoring hail fall in the vicinity of the Space Shuttle launch pads. An important outcome of this design is the opportunity to utilize frequency analysis to discriminate between the audio signal generated from raindrop impacts and that of hailstone impacts. The sound of hail impacting a metal plate is subtly but distinctly different from the sound of rain impacts. This useful characteristic permits application of signal processing algorithms that are inherently more robust than techniques relying on amplitude processing alone in the implementation of a hail disdrometer.