Disdrometer

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

20 GHz Specific attenuation calculations using drop size distributions and drop shape measurements from 2D video disdrometer data in different rain climates

Abstract: Specific attenuation calculations using drop size and drop shape data are presented for horizontal and vertical polarizations at 20 GHz. The data were obtained from several 2- dimensional video disdrometers located around the globe, ranging from mid-latitude to equatorial regions. The results are compared with predictions from the ITU- R recommendation P. 838 -3.

About the Impact of NWP Models’ Temporal Resolution on Rain Attenuation Forecasts

Abstract: The ever increasing demand for more data transmission capacities also includes the field of satellite communications. Satellite links with higher frequencies provide large bandwidths, but are more prone to degradation by atmospheric phenomena on the earth - space path. Reliable short term forecasts of weather and channel characteristics will ease appropriate mitigation, like employment of diversity techniques or adaptive code modulation. Numerical weather prediction (NWP) models area available on global scale as a potential basis for such forecasts. Rain is the strongest effect, with the rain rate being highly variable in time. This study discusses, what rain rate integration time and thus NWP forecast step width is suitable for forecasting satellite channel characteristics. The link attenuation is calculated on basis of disdrometer measurements for various integration times and the resulting fade slope statistics compared against the expectation by the ITU-R P.1623 model [1]. It is shown, that NWP models with forecast steps of 5 minutes or less are interesting for such purpose.

Rain drop size distribution over a tropical Indian station using ground-based disdrometer

Abstract: Tropical regions can be characterized as large fields of convective clouds of all sizes. Latent heat released is different for different precipitating systems like convective and stratiform. So we need to classify various precipitating systems. In the present study, ground based observations of Joss-Waldvogel Disdrometer (JWD) which was installed at Thumba (8.5°N, 76.9°E) under Ka band propagation experiment is used extensively to characterize the tropical rain. It can be noticed that the JWD is placed at calm and noise-free places, in order to make it sensitive to smaller drops. The JWD is a standard tool for precipitation measurements such as Drop Size Distribution (DSD), rainfall intensity, R, rain accumulation and liquid water content, W, reflectivity factor, Z. The range of drop diameters that can be measured spans from 0.3 to 5 mm with an accuracy of 5%. For present study Disdrometer data from June 2005 onwards are collected. The main objective of the present study is to classify precipitation system into Convective, Transition (an intermediate region) and stratiform. Since DSD integral parameters like rain rate (R), liquid water content (LWC), Reflectivity (Z) are different for different precipitating systems, so we need to classify these systems. There is a dearth of raindrop Size data and distribution models for the tropics, especially over Indian continent. Models for drop size distribution are required for the evaluation of microwave and millimeter wave propagation effects due to rainfall. In the present paper various DSD models namely gamma model and lognormal model with different combination of moments for observing the characteristic features of tropical rain are studied.