About: Disdrometer is a(n) research topic. Over the lifetime, 930 publication(s) have been published within this topic receiving 23092 citation(s).
Papers published on a yearly basis
01 Mar 2009-Monthly Weather Review
TL;DR: A two-moment cloud microphysics scheme predicting the mixing ratios and number concentrations of five species (i.e., cloud droplets, cloud ice, snow, rain, and graupel) has been implemented into the Weather Research and Forecasting model (WRF) as discussed by the authors.
Abstract: A new two-moment cloud microphysics scheme predicting the mixing ratios and number concentrations of five species (i.e., cloud droplets, cloud ice, snow, rain, and graupel) has been implemented into the Weather Research and Forecasting model (WRF). This scheme is used to investigate the formation and evolution of trailing stratiform precipitation in an idealized two-dimensional squall line. Results are compared to those using a one-moment version of the scheme that predicts only the mixing ratios of the species, and diagnoses the number concentrations from the specified size distribution intercept parameter and predicted mixing ratio. The overall structure of the storm is similar using either the one- or two-moment schemes, although there are notable differences. The two-moment (2-M) scheme produces a widespread region of trailing stratiform precipitation within several hours of the storm formation. In contrast, there is negligible trailing stratiform precipitation using the one-moment (1-M) scheme. The primary reason for this difference are reduced rain evaporation rates in 2-M compared to 1-M in the trailing stratiform region, leading directly to greater rain mixing ratios and surface rainfall rates. Second, increased rain evaporation rates in 2-M compared to 1-M in the convective region at midlevels result in weaker convective updraft cells and increased midlevel detrainment and flux of positively buoyant air from the convective into the stratiform region. This flux is in turn associated with a stronger mesoscale updraft in the stratiform region and enhanced ice growth rates. The reduced (increased) rates of rain evaporation in the stratiform (convective) regions in 2-M are associated with differences in the predicted rain size distribution intercept parameter (which was specified as a constant in 1-M) between the two regions. This variability is consistent with surface disdrometer measurements in previous studies that show a rapid decrease of the rain intercept parameter during the transition from convective to stratiform rainfall.
TL;DR: In this article, an empirical stratiform-convective classification method based on N 0 and R (rainfall rate) is presented. But, the occurrence of precipitation was found to be 74% (stratiform) and 26% (convection) but total rainfall, on the other hand, was...
Abstract: An analysis of temporal variations in gamma parameters of raindrop spectra is presented utilizing surface-based observations from the Tropical Ocean Global Atmosphere Couple Ocean-Atmosphere Experiment. An observed dramatic change in the N0 parameter, found to occur during rainfall events with little change in rainfall rate, is suggestive of a transition from rain of convective origin to rain originating from the stratiform portion of tropical systems. An empirical stratiform-convective classification method based on N0 and R (rainfall rate) is presented. Properties of the drop size spectra from the stratiform classification are consistent with micro-physical processes occurring within an aggregation/melting layer aloft, which produces more large raindrops and fewer small to medium size raindrops than rain from the convective classification, at the same rainfall rate. The occurrence of precipitation was found to be 74% (stratiform) and 26% (convective), but total rainfall, on the other hand, was ...
TL;DR: In this article, the application of polarimetric radar data to the retrieval of raindrop size distribution parameters and rain rate in samples of convective and stratiform rain types is presented.
Abstract: The application of polarimetric radar data to the retrieval of raindrop size distribution parameters and rain rate in samples of convective and stratiform rain types is presented. Data from the Colorado State University (CSU), CHILL, NCAR S-band polarimetric (S-Pol), and NASA Kwajalein radars are analyzed for the statistics and functional relation of these parameters with rain rate. Surface drop size distribution measurements using two different disdrometers (2D video and RD-69) from a number of climatic regimes are analyzed and compared with the radar retrievals in a statistical and functional approach. The composite statistics based on disdrometer and radar retrievals suggest that, on average, the two parameters (generalized intercept and median volume diameter) for stratiform rain distributions lie on a straight line with negative slope, which appears to be consistent with variations in the microphysics of stratiform precipitation (melting of larger, dry snow particles versus smaller, rimed ic...
TL;DR: In this article, a prototype optical disdrometer is presented, which is easy to handle, robust, and low cost, allowing a cluster of instruments to investigate the spatial and temporal fine-scale structure of precipitation, and it provides reliable detection of the range of small drops.
Abstract: The characteristics of a prototype optical disdrometer are presented. Particles are detectable in the diameter range from 0.3 to 30 mm having velocities of up to 20 m s−1. Advantages of the new system are (i) it is easy to handle, robust, and low cost, allowing a cluster of instruments to investigate the spatial and temporal fine-scale structure of precipitation; (ii) it provides reliable detection of the range of small drops; and (iii) it allows the possibility of snow measurements. Results of rain measurements are compared with data from a Joss–Waldvogel disdrometer and a Hellmann rain gauge. Furthermore, some snow measurements are presented and compared with results of a research spectrometer. The overall agreement is good. The repeatability of particle size estimation was checked in the diameter range between 1.4 and 8.0 mm and yielded a standard deviation of less than 5%. For drop velocities the standard deviation varies between 25% (0.3-mm drops) and 10% (5-mm drops). The optical disdromete...
TL;DR: In this paper, a unique dataset consisting of high-resolution polarimetric radar measurements and dense rain gauge and disdrometer observations collected in east-central Florida during the summer of 1998 was examined.
Abstract: A unique dataset consisting of high-resolution polarimetric radar measurements and dense rain gauge and disdrometer observations collected in east-central Florida during the summer of 1998 was examined. Comparison of the radar measurements and radar parameters computed from the disdrometer observations supported previous studies, which indicate that oscillating drops in the free atmosphere have more spherical apparent shapes in the mean than equilibrium shapes. Radar‐disdrometer comparisons improved markedly when using an empirical axis ratio relation developed from observational studies and representing more spherical drop shapes. Fixedform power-law rainfall estimators for radar reflectivity ( ZH), specific differential phase (KDP), specific differential phase‐differential reflectivity ( KDP, ZDR), and radar reflectivity‐differential reflectivity ( ZH, ZDR) were then determined using the disdrometer observations. Relations were produced for both equilibrium shapes and the empirical axis ratios. Polarimetric rainfall estimators based on more spherical shapes gave significantly improved performance. However, the improvement was largely in bias mitigation. Rainfall estimates with the ZH‐ZDR measurement pair had the highest correlation with rain gauge observations, the smallest range in bias factors from storm to storm, and the smallest root-mean-square error.
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