Topic
Disdrometer
About: Disdrometer is a research topic. Over the lifetime, 930 publications have been published within this topic receiving 23092 citations.
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TL;DR: In this article, the authors explored the effects of instrument sampling on the partitioning of the data record into rain events and found that sampling variability may result in event identifications that can statistically magnify the differences between two similar data records.
Abstract: The use of point detectors to measure properties of rainfall is ubiquitous in the hydrological sciences. An early step in most rainfall analysis includes the partitioning of the data record into “rain events.” This work utilizes data from a dense network of optical disdrometers to explore the effects of instrument sampling on this partitioning. It is shown that sampling variability may result in event identifications that can statistically magnify the differences between two similar data records. The data presented here suggest that these magnification effects are not equally impactful for all common definitions of a rain event.
13 citations
TL;DR: In this article, a procedure to correct the reflectivity data from multiple radars is proposed, where the TRMM/PR (Tropical Rainfall Measurement Mission satellite/Precipitation Radar) is used as the standard calibrator.
Abstract: A procedure to correct the reflectivity data from multiple radars is proposed. The TRMM/PR (Tropical Rainfall Measurement Mission satellite/Precipitation Radar) is used as the standard calibrator. The data from a disdrometer is also used to account for the effects of rain attenuation at short wavelengths. The procedure is evaluated in the case of oceanic rain observed in MISMO (Mirai Indian Ocean cruise for the Study of the MJO-convection Onset), in which two radars were deployed; a C-band shipborne radar and an X-band ground-based radar.On the C-band radar, the traditional corrections for the factors such as rain attenuation, second-trip echos, shadows by obstacles, and noise, result in reflectivity data which closely matches that of the TRMM/PR. For the X-band radar, iterative matching to the TRMM/PR worked effectively to correct the reflectivity, with the aid of the disdrometer data to reflect the attenuation by the rain in the vicinity of the radar. The corrected reflectivity from both radars well matches that of TRMM/PR with negligible biases and reduced deviations.
13 citations
TL;DR: In this article, a new relationship has been established linking the vertical mean Doppler velocity of raindrop spectra and the accompanying differential reflectivities, which is based upon the specific radar combination of a vertically pointing DOppler and a polarization radar scanning at low elevations, and was derived from consideration of two extensive disdrometer datasets containing 40 000 raindrop-size distributions.
Abstract: A new relationship has been established linking the vertical mean Doppler velocity of raindrop spectra and the accompanying differential reflectivities. It is based upon the specific radar combination of a vertically pointing Doppler and a polarization radar scanning at low elevations, and was derived from consideration of two extensive disdrometer datasets containing 40 000 raindrop-size distributions. Following a detailed error analysis of the new relation, the discussion is directed towards its possible application and limitation. It is shown that under optimum conditions the velocity errors are as low as 0.3 m s−1. This results in Doppler radar-derived drop-size distributions having liquid-water contents with uncertainties of only about 40%. Compared to standard particle fall speed estimations of the Rogers' type, this means an improvement in accuracy of more than a factor of three. Although the new technique is not suitable for operational use, it can provide fresh quantitative insight into ...
13 citations
01 Jan 2011
TL;DR: In this article, cell size statistics for the rainfall types in Durban, South Africa have been derived from a five-year, one-hour integration time series rain gauge network data.
Abstract: Cell size statistics for the rainfall types in Durban, South Africa have been derived from a five-year, one-hour integration time series rain gauge network data. The data have been converted to their equivalent one-minute integration time values and processed to determine the cell sizes for different rain rate above threshold values between 3 mm/h and 20 mm/h. The results are then compared to the cell size statistics from oneminute integration time data from disdrometer measurements taken for two years. By the use of the terrestrial link attenuation data obtained for Durban, the advection velocity for the stratiform rain has been derived as 6 m/s. The equivalent rain cell diameter model which is an input requirement in the proposed rain attenuation prediction equation and site diversity separation distance has been derived.
13 citations
TL;DR: In this paper, a new composite method is proposed that weights the algorithms by the inverse of their theoretical error, and the resultant algorithms show modest improvement over composite methods based on decision-tree logic, in particular at rain rates above 20 mm h−1.
Abstract: The algorithms used to estimate rainfall from polarimetric radar variables show significant variance in error characteristics over the range of naturally occurring rain rates. As a consequence, to improve rainfall estimation accuracy using polarimetric radar, it is necessary to optimally combine a number of different algorithms. In this study, a new composite method is proposed that weights the algorithms by the inverse of their theoretical error. A number of approaches are discussed and are investigated using simulated radar data calculated from disdrometer measurements. The resultant algorithms show modest improvement over composite methods based on decision-tree logic—in particular, at rain rates above 20 mm h−1.
13 citations