A dual-beam spectropluviometer concept

Delahaye, Jean-Yves; Barthès, Laurent; Golé, P.; Lavergnat, J.; Vinson, Jean-Paul

doi:10.1016/j.jhydrol.2005.11.048

Cited by 31 publications

(28 citation statements)

References 14 publications

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“…This research relies on the analysis of raindrop measurements obtained with a dual-beam spectropluviometer (DBS) disdrometer, first described by Delahaye et al (2006). This instrument allows the arrival time, diameter and fall velocity of incoming drops to be recorded.…”

Section: The Disdrometer Data Sets -Data Processing Methodologymentioning

confidence: 99%

Data-driven clustering of rain events: microphysics information derived from macro-scale observations

et al. 2017

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Abstract. Rain time series records are generally studied using rainfall rate or accumulation parameters, which are estimated for a fixed duration (typically 1 min, 1 h or 1 day). In this study we use the concept of "rain events". The aim of the first part of this paper is to establish a parsimonious characterization of rain events, using a minimal set of variables selected among those normally used for the characterization of these events. A methodology is proposed, based on the combined use of a genetic algorithm (GA) and self-organizing maps (SOMs). It can be advantageous to use an SOM, since it allows a high-dimensional data space to be mapped onto a two-dimensional space while preserving, in an unsupervised manner, most of the information contained in the initial space topology. The 2-D maps obtained in this way allow the relationships between variables to be determined and redundant variables to be removed, thus leading to a minimal subset of variables. We verify that such 2-D maps make it possible to determine the characteristics of all events, on the basis of only five features (the event duration, the peak rain rate, the rain event depth, the standard deviation of the rain rate event and the absolute rain rate variation of the order of 0.5). From this minimal subset of variables, hierarchical cluster analyses were carried out. We show that clustering into two classes allows the conventional convective and stratiform classes to be determined, whereas classification into five classes allows this convective-stratiform classification to be further refined. Finally, our study made it possible to reveal the presence of some specific relationships between these five classes and the microphysics of their associated rain events.

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Section: The Disdrometer Data Sets -Data Processing Methodologymentioning

confidence: 99%

Data-driven clustering of rain events: microphysics information derived from macro-scale observations

et al. 2017

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“…1e) at the SIRTA observatory. Rain rate was measured during a rain event by the dual-beam spectropluviometer (DBS; Delahaye et al 2006), which was developed at LATMOS and operated at SIRTA only a few meters away from the radars. The concept of the Hogan et al (2003) calibration technique is to simultaneously measure radar reflectivity at 500-m range and rain rate in light rain, and to compare the obtained relationship between these two measurements to that predicted assuming a shape for the raindrop size distribution and assuming that the path attenuation over a few hundred meters in light rain is small or corrected from attenuation.…”

Section: Calibrationmentioning

confidence: 99%

BASTA: A 95-GHz FMCW Doppler Radar for Cloud and Fog Studies

Delanoë

Protat

Vinson

et al. 2016

Journal of Atmospheric and Oceanic Technology

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Doppler cloud radars are amazing tools to characterize cloud and fog properties and to improve their representation in models. However, commercially available cloud radars (35 and 95 GHz) are still very expensive, which hinders their widespread deployment. This study presents the development of a lower-cost semioperational 95-GHz Doppler cloud radar called the Bistatic Radar System for Atmospheric Studies (BASTA). To drastically reduce the cost of the instrument, a different approach is used compared to traditional pulsed radars: instead of transmitting a large amount of energy for a very short time period (as a pulse), a lower amount of energy is transmitted continuously. By using a specific signal processing technique, the radar can challenge expensive radars and provide high-quality measurements of cloud and fog. The latest version of the instrument has a sensitivity of about −50 dBZ at 1 km for 3-s integration and a vertical resolution of 25 m. The BASTA radar currently uses four successive modes for specific applications: the 12.5-m vertical resolution mode is dedicated to fog and low clouds, the 25-m mode is for liquid and ice midtropospheric clouds, and the 100- and 200-m modes are ideal for optically thin high-level ice clouds. The advantages of such a radar for calibration procedures and field operations are also highlighted. The radar comes with a set of products dedicated to cloud and fog studies. For instance, cloud mask, corrected Doppler velocity, and multimode products combining the high-sensitivity mode and high-resolution modes are provided.

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“…In the case of the present study, the use of 12 GHz links could be expected to be more or less sensitive to the rain microphysics. In order to assess its impact, 1 min drop size distributions were computed from the raindrop dataset collected by a disdrometer (Delahaye et al, 2006) over a period of 24 months between July 2008 and July 2010. Through the use of an approach similar to that proposed by Leijnse et al (2010), for each DSD, the corresponding rain rate value R and specific attenuation values k fp (Eq.…”

Section: Accuracy Of the K-r Power Law Relationshipmentioning

confidence: 99%

Rainfall measurement from the opportunistic use of an Earth–space link in the Ku band

Barthès

Mallet

2013

Atmos. Meas. Tech.

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The present study deals with the development of a low-cost microwave device devoted to the measurement of average rain rates observed along Earth–satellite links, the latter being characterized by a tropospheric path length of a few kilometres. The ground-based power measurements, which are made using the Ku-band television transmissions from several different geostationary satellites, are based on the principle that the atmospheric attenuation produced by rain encountered along each transmission path can be used to determine the path-averaged rain rate. This kind of device could be very useful in hilly areas where radar data are not available or in urban areas where such devices could be directly placed in homes by using residential TV antenna.

The major difficulty encountered with this technique is that of retrieving rainfall characteristics in the presence of many other causes of received signal fluctuation, produced by atmospheric scintillation, variations in atmospheric composition (water vapour concentration, cloud water content) or satellite transmission parameters (variations in emitted power, satellite pointing). In order to conduct a feasibility study with such a device, a measurement campaign was carried out over a period of five months close to Paris.

The present paper proposes an algorithm based on an artificial neural network, used to identify dry and rainy periods and to model received signal variability resulting from effects not related to rain. When the altitude of the rain layer is taken into account, the rain attenuation can be inverted to obtain the path-averaged rain rate. The rainfall rates obtained from this process are compared with co-located rain gauges and radar measurements taken throughout the full duration of the campaign, and the most significant rainfall events are analysed

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A dual-beam spectropluviometer concept

Cited by 31 publications

References 14 publications

Data-driven clustering of rain events: microphysics information derived from macro-scale observations

Data-driven clustering of rain events: microphysics information derived from macro-scale observations

BASTA: A 95-GHz FMCW Doppler Radar for Cloud and Fog Studies

Rainfall measurement from the opportunistic use of an Earth–space link in the Ku band

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