Disdrometer

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

Z-R Relationships for Weather Radar in Indonesia from the Particle Size and Velocity (Parsivel) Optical Disdrometer

Abstract: The relationship between the radar reflectivity factor ( $Z$ ) and rainfall rate ( $R$ ), which is called the $Z-R$ relationship $(Z=AR^{b})$ , is important to convert $Z$ from weather radar to $R$ because a weather radar does not measure the rainfall amount directly. The $Z-R$ relationship can be governed from raindrop size distribution (DSD) data. However, the DSD varies not only within a specific storm type but also across different storm types and climatic regimes. Therefore, the use of a single $Z-R$ relation such as a climatological $Z-R$ relationship type $Z=200R^{1.6}$ (Marshall-Palmer) for converting radar reflectivity into $R$ will underestimate or overestimate rainfall rate. In this research, the $Z-R$ relationships for weather radar in Indonesia were governed through a network of the Particle Size and Velocity (Parsivel) optical disdrometer along equatorial Indonesia. The Parsivel were installed at Manado (Sulawesi) and Biak (Papua). In addition to the aforementioned sites, we have been conducting DSD observations at Padang, Sicincin, Kototabang (Sumatra) and Pontianak (Kalimantan). In general, the coefficients $A$ and $b$ of $Z-R$ equations vary from 200–400 and 1.36-1.47, respectively. This value shows a significant diurnal variation. In Biak and Manado, coefficient $A$ during 00–11 local time (LT) is larger than that during 12–23 LT. However, in Sicincin, Padang, Kototabang and Pontianak, coefficient $A$ during 00–11 LT much smaller than that during 12–23 LT. It was also found that coefficient $A$ in Pontianak is much larger than other sites which indicates a higher concentration of large size drop in this area as seen from a larger value of mass-weighted mean diameter $(D_{m})$ .

The Characteristics of Raindrop Size Distribution at Windward and Leeward Side over Mountain Area

Abstract: To analyze the difference in the microphysical development characteristics of orographic rainfall, several Parsivel disdrometers were installed along the windward and leeward slope of a mountain. There were differences in the raindrop size distribution according to the difference in height and distance from the center of the mountain. In low-altitude coastal areas and adjacent areas, the number concentration of raindrops smaller than 1 mm was relatively lower than in mountainous areas, and the rain rate increased with the growth in the size of the raindrops. On the other hand, a higher rain rate was observed as the number concentration of raindrops smaller than 1 mm increased in the hillside area. The increase in the number concentration of small raindrops was evident at the LCL (lifting condensation level) altitude. The main factors affecting the increase in the rain rate on the windward and leeward slopes were the concentration of raindrops and the growth of raindrops, which showed regional differences. As a result of a PCA (principal component analysis), it was found that raindrop development by vapor deposition and weak convection were the main rainfall development characteristics on the windward and leeward slopes, respectively. The difference in regional precipitation development characteristics in mountainous areas affects the parameters of the rainfall estimation relational expression. This means that the rainfall relation calculated through the disdrometer observation data observed in a specific mountainous area can cause spatial and quantitative errors.

Measurement of drop size distribution rain in mataram utilize disdrometer acoustic for floods prediction

Abstract: This paper present from result of research on prediction and made early warning system for occurrence of floods and landslides are frequently associated with high intensity rainfall and precipitation with a long duration in tropical climate. Raindrops the size of the large fall in the earth's surface even though in short duration or small fall long duration can be a big contributor for floods. Drop size distribution rain measured by acoustic disdrometer. The water level rises to the occurrence of rain varies greatly, according to the conditions of rain that fell in the direct measurement of water level in the river rises 0.01 per hours of the incident if stratiform. In convective the water level rise of 0.4 meters per hour in river downstream. Lognormal distribution model has an error rate condition or standard error fit small, amounting to 0,072 m-3mm-1. The path length of the Jangkok River is 47.1 km potential floods. Prediction floods can occur if the convective rains occur within the confines of more than 9 hours continuously.

Skewness as measure of the invariance of instantaneous renormalized drop diameter distributions - Part 2: Orographic precipitation

Abstract: Here we use the skewness parameter, and the procedure developed in the companion paper (Ignaccolo and De Michele, 2012), to investigate the variability of instantaneous renormalized spectra of rain drop diameter in presence of orographic precipitation. Disdrometer data, available at Bodega Bay and Cazadero, California, are analyzed either as a whole, or as divided (using the bright band echo) in precipitation intervals weakly and strongly influenced by orography, and compared to results obtained at Darwin, Australia. We find that also at Bodega Bay and Cazadero exists a most common distribution of the skewness values of instantaneous spectra of drop diameter, but peaked at values greater than 0.64, found at Darwin. No appreciable differences are found in the skewness distributions of precipitation weakly and strongly influenced by orography. However the renormalized drop diameter spectra of precipitation with strong orographic component have fatter right tail than precipitation with a weaker orographic component. The differences between orographic and non-orographic precipitation are investigated within the parametric space represented by number of drops, mean value and standard deviation of drop diameter. A filter is developed which is able to identify 1 min time intervals during which precipitation is mostly of orographic origin.