New laser technology to determine present weather parameters

Abstract

Present weather sensors are becoming increasingly important as a means to augment networks of automated weather stations and extend the capability of manned observations. The classification of hydrometeors is one of the principal tasks that is addressed by present weather sensors. In this paper we discuss new laser based technology for this purpose. The system improves upon current precipitation monitors by using a derivative of Phase Doppler Anemometry techniques to accurately determine particle speed and size. The instrument is also capable of distinguishing between liquid droplets and solid polycrystalline hydrometeors and can be used to estimate visibility. The incorporation of this technology into a meteorological station with other sensors, such as temperature and relative humidity probes leads to the accurate classification of particle type. The example data shown is taken from tests in Leicestershire, England and Utah, USA and shows the differences between solid and liquid precipitation events.

Two months of disdrometer data in the Paris area

“…Computations are carried out assuming a spherical shape and a correction accounting for oblateness is then implemented. More details can be found in Ellis et al (2006) or in the device documentation (CampbellScientific-Ltd, 2012). Actually authors found possible to improve the oblateness correction of the PWS100 rationale (Gires 5 et al, 2017a) and used it in previous studies (Gires et al, 2015).…”

Multifractal comparison of the outputs of two optical disdrometers

“…The first ones were impact disdrometers (Joss and Waldvogel 1967), and now optical ones (Loffler-Mang and Joss 2000, Ellis et al 2006, Battaglia et al 2010, Frasson et al 2011) are more commonly used for operational and research purposes. The great advantage of these devices with regards to more conventional rain gauges is that they do not measure only a rain rate (or rainfall depth) but information about size and fall velocity for all the hydrometeors passing through the sampling area whose size is few tens of cm 2 .…”

Two months of disdrometer data in the Paris area

“…Computations are carried out assuming a spherical shape, and a correction accounting for oblateness is then implemented. More details can be found in Ellis et al (2006) or in the device documentation (Campbell-Scientific-Ltd, 2012). Actually the authors could improve the oblateness correction of the PWS100 rationale (Gires et al, 2017) and used it in previous studies (Gires et al, 2015).…”

“…Now the most commonly used operationally are optical ones. They are made of a transmitter generating one or several laser sheet(s) and receiver(s) measuring either the occluded light (Loffler-Mang and Joss, 2000;Battaglia et al, 2010;Delahaye et al, 2006;Frasson et al, 2011) or the refracted light (Ellis et al, 2006) from the drops falling through a sampling area of roughly a few tens of cm 2 . The received signal is then processed to estimate the size (more precisely an equivolumic diameter, i.e.…”

“…More sophisticated disdrometers, such as the 2-D video one, can also provide access to images of the falling hydrometeors (Kruger and Krajewski, 2002). Numerous studies have been carried out to compare the output of various types of disdrometers, usually with the more conventional rain gauges (Miriovsky et al, 2004;Krajewski et al, 2006;Frasson et al, 2011;Thurai et al, 2011).…”