Path-average rainfall estimation from optical extinction measurement using a large-aperture scintillometer

R. Uijlenhoet, J.M. Cohard, M. Gosset

Research output: Contribution to conferenceAbstractAcademic

Abstract

We employ a Scintec BLS900 near infrared (880 nm) large aperture boundary layer scintillometer as path average rain gauge. The instrument was installed over a path of 2.4 km in Benin as part of the AMMA CATCH (African Monsoon Multidisciplinary Analysis) intensive observation period during 2006 and 2007. Measurements of the one minute average and variance of the received signal intensity from two transmitter disks of 462 LEDs each, operating at a pulse repetition rate of 5 Hz (i.e. 300 samples per minute), were collected for a few rainfall events that occurred during the dry season and several events during the wet season. Using estimates of the signal base level just before the start of the rain events, the optical extinction coefficient was estimated from the path integrated signal attenuation for each minute. The corresponding one minute path average rain rates were computed using a power law relation between the optical extinction coefficient and rain rate obtained from measurements of raindrop size spectra with an optical spectropluviometer. The estimated rain rates are compared to measurements from nearby rain gauges. Our results demonstrate the potential of optical extinction measurements from large aperture boundary layer scintillometers to obtain estimates of rainfall variability at high temporal resolution for hydrologically relevant spatial scales.
Original languageEnglish
Publication statusPublished - 2009
EventFall Meeting of the American Geophysical Union -
Duration: 15 Dec 200819 Dec 2008

Conference

ConferenceFall Meeting of the American Geophysical Union
Period15/12/0819/12/08

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