Disdrometer

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

Effect of the Resolution of Tipping-Bucket Rain Gauge and Calculation Method on Rainfall Intensities in an Andean Mountain Gradient

Abstract: A laser-optical disdrometer served as reference to assess the absolute percent bias of calculated rainfall intensity using the data of different-resolution tipping-bucket rain gauges classically applied by climatologists and hydrologists in the Andean region. Additionally, the impact of the calculation method (tip counting versus cubic spline interpolation) was examined. The combined effect was assessed for different rainfall intensity classes (0–0.99, 1–1.99, 2–4.99, and 5–10 mm·h−1) and timescales (5, 10, 30, and 60 min). Additionally, the variation in percent absolute bias of the Davis rain gauge, the collector most widely used in the study region, was defined with respect to the Texas rain gauge along an elevation gradient between 3300 and 4000 m a.s.l. Results reveal that the value of the percent absolute bias is largest for small rainfall intensities (≤2 mm·h−1) and short timescales (≤10 min), and decreases when the cubic spline interpolation is used. No relation was found between the error, the elevation, and rainfall depth along the gradient. Based on the research findings, it is recommended to measure precipitation in the high Andean mountain region with a high-resolution sensor and to consider cubic spline for the computation of intensities.

Two Distinct Modes in One-Day Rainfall Event during MC3E Field Campaign: Analyses of Disdrometer Observations and WRF-SBM Simulation

Abstract: A unique microphysical structure of rainfall is observed by the surface laser optical Particle Size and Velocity (Parsivel) disdrometers on 25 April 2011 during Midlatitude Continental Convective Clouds Experiment (MC3E). According to the systematic differences in rainfall rate and bulk effective droplet radius, the sampling data can be divided into two groups; the rainfall mostly from the deep convective clouds has relatively high rainfall rate and large bulk effective droplet radius, whereas the reverse is true for the rainfall from the shallow wrm clouds. The Weather Research and Forecasting model coupled with spectral bin microphysics (WRF-SBM) successfully reproduces the two distinct modes in the observed rainfall microphysical structure. The results show that the up-to-date model can demonstrate how the cloud physics and the weather condition on the day are involved in forming the unique rainfall characteristic.

Rainfall interception and drop size-development and calibration of the two-layer stochastic interception model.

Abstract: This paper reviews the development of the stochastic interception model from the original, single-layer, drop-size-dependent model to the two-layer model that recognizes that vegetation canopies are wetted through both the primary impact of raindrops to the top layer of the canopy and secondary impacts from drops falling from the vegetation to lower layers of the canopy. It is shown that drop volumes of primary raindrops can be calculated from the Marshall-Palmer distribution and drop volumes of secondary drops can be estimated from disdrometer measurements of the characteristic volume appropriate to the particular vegetation species. It is recognized that, in addition to the volume-dependent stochastic wetting effect, there is also another drop-size-dependent wetting effect that is related to the kinetic energy of the raindrops, which reduces the maximum storage that can be achieved on the canopy. The predicted wetting functions for canopies of different density are described and compared with observations made with the use of a rainfall simulator. It is also shown that the species-dependent model parameters can be determined from measurements made with the rainfall simulator. The improved performance of the model compared with conventional interception models is demonstrated for a tropical forest in Sri Lanka. Application of the two-layer model may explain why interception losses from coniferous, fine-leaved forests in the temperate, low-intensity rainfall climate of the uplands of the U.K. are among the highest in the world, whereas interception losses from tropical broad leaved forest in high-intensity rainfall climates of the tropics are among the lowest.

Experimental Test of the Effects of Z–R Law Variations on Comparison of WSR-88D Rainfall Amounts with Surface Rain Gauge and Disdrometer Data

Abstract: Reflectivity factors and rainfall rates found from Level II WSR-88D data for the National Weather Service (NWS) radar in Greer, South Carolina (KGSP), are compared with similar parameters found from disdrometer data collected at the Clemson Atmospheric Research Laboratory. These comparisons are used to determine experimentally the sensitivity of rainfall amounts found from the WSR-88D data to variations in the parameters A and b of the Z–R law (Z = ARb) that is used in analysis of the data. Analyses of data for nine storms in upstate South Carolina are described. These nine cases encompass a variety of rainfall types including stratiform rain, airmass thunderstorms, and strong cold front convective activity. It is found, after correction of the radar reflectivity factors for obvious calibration offset, that the rainfall depths found by radar are in good agreement with those found from the disdrometer when the NWS default values of A and b (A = 300, b = 1.4) are used. If the values of A and b foun...