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Topic: Disdrometer

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	NOAA ESRL TRMM LBA (Site not responding. Last check: 2007-10-13)
		The JWD is an impact disdrometer that produces a voltage when a drop strikes the surface of its 50 square centimeter styrofoam cone.
		The observing volume of the disdrometers is determined by the fall velocity of raindrops and for drops falling at 7 meters per second would be close to 1m^3 for a 30-second sample while the volume observed by the 2DVD is about 2.1 m^3.
		When the disdrometer values are at the high end of the distribution and there is increasing decorrelation with the profiler values, a given large disdrometer reflectivity is increasingly likely to be associated with a smaller profiler reflectivity.
	www.esrl.noaa.gov /psd/psd5/trmm/trmmlba/calibration.html (4108 words)

	Learn more about Disdrometer in the online encyclopedia. (Site not responding. Last check: 2007-10-13)
		A disdrometer is an instrument used to measure the drop size distribution and fall velocity of hydrometeors.
		Some disdrometers can distinguish between rain, graupel, and hail.
		The latest disdrometers employ microwave or laser technologies.
	www.onlineencyclopedia.org /d/di/disdrometer.html (148 words)

	NSSL 2DVD Page (Site not responding. Last check: 2007-10-13)
		The disdrometer consists of three interdependent units: 1) a sensor unit, 2) an outdoor electronic unit, and 3) an indoor user terminal.
		A disdrometer is an instrument that measures the size of rain drops.
		This disdrometer, which is developed by a small research company in Austria, is unique in that it records two, side view optical images of each raindrop.
	cimms.ou.edu /~schuur/disdrom/poster.html (245 words)

	PACJET Instrumentation (Site not responding. Last check: 2007-10-13)
		The Distromet LTD Model RD-80 disdrometer uses the momentum of falling raindrops to measure the size distribution of rain.
		The amplitude of the pulse generated as a drop hits the disdrometer's electromechanical transducer is roughly proportional to the drop's momentum and, ultimately, the drop's diameter.
		The integrated size distribution measured by the disdrometer is a direct measurement of the rainfall intensity, which will be compared to the rainfall intensities measured by a variety of other rain gauges and estimated by the radars.
	www.etl.noaa.gov /programs/2003/pacjet/instruments.html (510 words)

	TRMM-LBA - ESPO-Earth Science Project Office (Site not responding. Last check: 2007-10-13)
		The 2-D video disdrometers will require more elaborate set-up, calibration, and maintenance and therefore will likely be deployed at the beginning of the IOP (e.g., first week of January 1999).
		This multi-instrumented (profilers, disdrometers, gauges) ground validation network should provide unprecedented observations of DSD, rainfall rate, and precipitation vertical structure in tropical continental rainfall and will be crucial to achieve improved understanding of the ground radar (both polarimetric and Doppler) and the TRMM satellite measurements.
		The purpose of separating 24 gauges and 10 disdrometers into two separate networks is to maximize the probability of capturing a significant rainfall event on any given day while still allowing the investigation of rainfall spatial variability on small scales.
	cloud1.arc.nasa.gov /trmmlba/planb.html (1408 words)

	Disdrometer Data from KWAJEX
		APL disdrometers were located on Kwajalein, Meck, Legan, Roi-Namur, NOAA Ron-Brown research vessel (2 units), Woja, Lae, and on the west and east buoys.
		The preliminary analysis of the APL disdrometers on Meck and Legan showed substantial biases with collocated Joss-Waldvogel disdrometer and rain gauges.
		NOTE: Following the manufacturer instructions, the Joss-Waldvogel Disdrometer data were calculated both with and without the "dead-time correction." The dead-time correction is an empirical formula used to compensate for the underestimation of small drops in heavy rain.
	daac.gsfc.nasa.gov /fieldexp/TRMM_FE/kwajex/nasa_disdrom.shtml (539 words)

	IFM-GEOMAR: Lempio, Guido
		The optical disdrometer is an improved version of the ODM 470 disdrometer.
		The main advantage of this optical disdrometer is its ability to measure accurately precipitation even under high wind speeds.
		The result of the model study was applied to the disdrometer data set of a measurement campaign from winter 1999/2000 in Uppsala/Sweden and was compared to the data set of a Geonor gauge and to manual measurements.
	www.ifm-geomar.de /index.php?id=3276&L=1 (206 words)

	[No title]
		In the figure left, the number flux at the disdrometer (open circles) and at the optical spectrometer (solid boxes) is shown in dependance of the position parameter H. Here it has to be noted that the position parameter H is a reference to the height only of the optical spectrometer within the melting layer.
		The disdrometer stands throughout the whole experiment at the bottom station and measures rain from the begin to the end.
		However, the NF at the disdrometer can also be depicted in dependence of the position parameter H, simply by using the same transformation from time to H as was used to calculate the position of the optical spectrometer.
	www.iac.ethz.ch /staff/eszter/res.html (1833 words)

	NOAA ESRL TRMM TEFLUN-B (Site not responding. Last check: 2007-10-13)
		To refine the calibration for the final data set, we rely on measurements made with a collocated disdrometer to calibrate profiler reflectivites in precipitation.The Joss-Waldvogel (JWD) impact disdrometer manufactured by Distromet is utilized for this purpose.
		The calibrated value determined by intercomparing with the JWD disdrometer is given by 25.93.
		For similar reasons a small disdrometer reflectivity is increasingly likely to be associated with a larger profiler reflectivity.
	www.esrl.noaa.gov /psd/psd5/trmm/teflunb/calibration.html (4263 words)

	Remote Sensing
		The data are being analyzed by Kyoko Ikeda, Ed Brandes, and Guifu Zhang in support of ongoing activities with polarimetric radar to develop algorithms for classifying hydrometeor types, quantifying winter precipitation, and improving the parameterization of winter storm microphysics in numerical forecast models.
		Snow density was computed from precipitation volume estimates from the disdrometer and mass from precipitation gauges.
		An ability to match radar measurements and disdrometer observations is requisite in the development of radar-based algorithms for discriminating between hydrometeor types and improving the quantification of winter precipitation.
	www.asr.ucar.edu /2004/RAP/remote-sensing.htm (529 words)

	Measurements of wind, rain and driving rain at the TUE site
		The raw data of the disdrometer will be treated differently from the data on wind, horizontal rain and driving rain.
		The disdrometer was operational from 1999-10-01 09:30 till 2000-01-11 15:30.
		/disdro were left in their original format as given by the disdrometer.
	sts.bwk.tue.nl /drivingrain/cd/info/manual.htm (2001 words)

	53:078 Principles of Hydrology (Precipitation)
		This is an 2-D optical disdrometer, which measures the characteristics of rain drops.
		The video disdrometer is able to detect the size and shape of each drop as it passes the sensor opening.
		This figure shows streamlines and velocity contours in the vicinity of the disdrometer for a uniform upstream wind velocity of 1 m/s.
	www.engineering.uiowa.edu /~flood/Archive/web/precip_measure.html (734 words)

	TRMM LBA Rain Gauge/Disdrometer Draft Operations Plan
		This multi-instrumented (profilers, disdrometers, gauges) ground validation network should provide unprecedented observations of DSD, rainfall rate, and precipitation vertical structure in tropical continental rainfall and will be crucial to achieve improved understanding of the ground radar (both polarimetric and Doppler) measurements and the TRMM satellite measurements.
		Similar to the rain gauge and impact disdrometer tasks, the RGDS is expected to utilize assistance from scientists dedicated to other platforms (e.g., TOGA or S-POL radar crew members) to assist in the maintenance and monitoring of the 2DVDS.
		Because the gauges and disdrometers are distributed over a relatively large area and because accessibility may be difficult in the wet season, it is expected that the RGDS will spend each day collecting data from a small subset of the gauges and APL disdrometers.
	olympic.atmos.colostate.edu /lba_trmm/gauge.html (2588 words)

	TRMM-LBA - ESPO-Earth Science Project Office (Site not responding. Last check: 2007-10-13)
		Therefore, all rain gauges and their collocated APL disdrometers should be checked and their data down loaded and saved with a laptop PC apporximately once a week.
		Because the gauges and disdrometers are disdtributed over a relatively large area and because of the fact that accessibility may be difficult in the wet season, it is expected that the RGDS will spend each day collecting data from a small subset of the gauges and APL disdrometers.
		Similar to the rain gauge and impact disdrometer tasks, the RGDS is expected to utilize assistance from scientists dedicated to other platforms (e.g., TOGA or SPOL radar crew memebers) to assist in the maintenance and monitoring of the 2DVDs.
	cloud1.arc.nasa.gov /trmmlba/plan2e.html (983 words)

	Distromet LTD. Product description
		The disdrometer for rain drops is an instrument for measuring rain drop size distributions continuously and automatically.
		A computer program, which is delivered with the disdrometer system, can be used to put the data in a suitable format for recording on a file.
		The disdrometer for rain drops consists of two units: the sensor, which is exposed to the rain and the processor for analog processing and digitizing of the sensor signal.
	www.distromet.com /1_inhalt_e.htm (963 words)

	Laser precipitation monitor (Disdrometer)
		A main advantage of the disdrometer is to measure particles down to 0,16 mm diameter.
		The disdrometer calculates the intensity (rain rate), volume and the spectrum of the different kinds of precipitation and makes necessary plausibility checks.
		he disdrometer is nearly maintenance- free, and the optical components are secured against environmental influence.
	www.thiesclima.com /disdrometer.htm (340 words)

	IERSD-NOA-RADAR
		NOA's 2-D video disdrometer is also one of a small number of such instruments worldwide.
		The system has a resolution of 0.2mm and estimates the fall velocity, the horizontal velocity, the diameter, the oblateness and the canting angle of each particle, the dropsize distribution and the rain rate with an accuracy of better than 10%.
		The disdrometer and the rain gauges provide reference measurements of rain characteristics for calibration and validation of the measurements of the X-POL radar.
	www.meteo.noa.gr /ENG/iersd_radar.htm (337 words)

	Quantification of the radar reflectivity sampling error in non-stationary rain using paired disdrometers
		Disdrometer measurements of DSDs are affected by uncertainties due to the limited sampling volumes or areas of the sensors.
		Determining this sampling error directly from disdrometer observations is of primary importance for the practical application of DSD analyses.
		However, we also show that its accuracy depends on the ratio between the length of the disdrometer time series involved and the characteristic time scale of the rainfall.
	www.agu.org /pubs/crossref/2005/2005GL024030.shtml (290 words)

	ER-2 sortie #98-105 (Site not responding. Last check: 2007-10-13)
		The 2-D video disdrometers required daily monitoring, but we were able to keep both instruments running with mininal downtime.
		I performed about three calibrations on the NASA disdrometer and was looking at standard deviations of about.03 mm across all sizes from 10 mm down to 1 mm.
		From my experience, this disdrometer is revolutionary in that it provides accurate information on every drop, which includes the diameter, oblateness factor, terminal fall speed, and horizontal velocity.
	rsd.gsfc.nasa.gov /912/geerts/trmm_lba/gage_lba.html (300 words)

	Dual Polarization Attenuation Mitigation
		The method is described here and evaluated with two unique experimental testbeds, one is in Japan in collaboration with National Institute of Earth Science and Disaster Prevention (NIED), the other is in Colorado Front Range during the Global Precipitation Measurement (GPM) Pilot Experiment.
		The dot marks denote the mean values from the simulations based on disdrometer.
		The grey shaded area denote the disdrometer inferences.
	www.casa.umass.edu /research/S17bposter.html (536 words)

	h31a in sm04 (Site not responding. Last check: 2007-10-13)
		The disdrometers were installed in a rectangular grid where the spacing was 127 cm by 140 cm.
		The JW disdrometer has been considered a standard instrument in measuring drop size distribution and widely used to derive the relationships between the radar measurements and rain rate.
		In the paper, time series of ground-based video disdrometer observations of raindrop number concentration and mass distribution as well as values normalized by mass-weighted size and liquid water content for thunderstorms are presented.
	www.agu.org /cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=sm04&database=/data/epubs/wais/indexes/sm04/sm04&maxhits=200&="H31A" (8073 words)

	IIHR's 2-D Video Disdrometer, IIHR, College of Engineering, The University of Iowa
		IHR's 2-D video disdrometer was purchased with NSF support from Joanneum Research, Graz, Austria.
		The original disdrometer experienced some temperature-related problems during a NASA/TRMM field campaign, and IIHR personnel subsequently enhanced the disdrometer by combining the different units in an air-conditioned housing and by adding software for synchronizing data collection.
		The light sheets are spaced 6 mm apart; this is used to measure the vertical fall velocity.
	www.iihr.uiowa.edu /facilities/disdrometer/index.html (197 words)

	Florida Bay Rainfall Analysis (Willis and Marks)
		A raindrop disdrometer was operated during the 1996 rainy season at a site at the Everglades National Park Research Center located at 25.390°N, 80.681°W. A continuous record of 1 -min DSDs was obtained.
		A Z-R relation was derived in the conventional manner by fitting a power law regression of Z vs. R, where both Z and R are calculated from the 1-min DSD data.
		5 the relation between the Z calculated from the 1-min disdrometer DSD's is regressed with the 1-min R from the capacitive rain gage, and a relation of Z=222R
	www.aoml.noaa.gov /hrd/FlBay/florida_bay_99.html (1235 words)

	3.2 Instrumentation
		1998] describe a disdrometer (originally from 1969) which uses this principle and which was improved by them.
		In our choice for a disdrometer, the directness of the drop size measurement principle, the (in)sensitivity to wind, the resolution in time and space, the easiness of use and the price were the most important criteria.
		The disdrometer was delivered in December 1998, but it took a year of testing and improvements (by the manufacturer) before the disdrometer became really operational on 1 October 1999.
	sts.bwk.tue.nl /drivingrain/fjrvanmook2002/node12.htm (3223 words)

	Holographic disdrometer for research of hard phase
		Holographic disdrometer let to measure the parameters of hard particles or liquid drops in two-phase objects: size (3-500 mikron), form, concentration (bis 60% transparence), velocity (0,1-5000m/s),etc., simultaneously in 3D-space.
		At the same time, the accuracy of the particles size measurement can be less than 10%, the error of velocity determination - less than 3%.
		The time resolution of disdrometer can be within 0,2-20 ns.
	home.planet.nl /~icblsec/isbl99/ab_poska2.html (134 words)

	RAP - General Information - Seminar Series
		As part of a program to evaluate the utility of polarimetric radar for estimating rainfall, the National Center for Atmospheric Research's S-band, dual-polarization radar was deployed in east central Florida during the summer of 1998.
		Comparisons between radar measurements and radar parameters derived from disdrometer observations (assuming a gamma drop-size distribution and equilibrium axis ratios) revealed that radar estimates of differential reflectivity and specific differential phase were significantly less than those determined from disdrometer observations.
		Florida relations, tuned with disdrometer observations, yielded a bias of 8% for the Z
	www.rap.ucar.edu /general/seminarseries/ss1-31-01.htm (262 words)

	Search SPIE Papers - Publications - SPIE Web
		Second, the accuracy of the rainrate estimate was studied based on disdrometer measured data.
		Based on the disdrometer data, snow particle distribution was generated using non-coalescence, non-breakup assumption.
		The retrieved drop size parameters were compared to corresponding disdrometer data and found that there is reasonably good agreement between the measurements, lending credence to the profiler retrievals of DSD parameters.
	www.spie.org /app/publications/index.cfm?fuseaction=toc&volume=4152&view=1 (7675 words)

	Florida Bay Rainfall Study
		As we were loitering over Florida Bay we noticed that the convective precipitation system we had just sampled continued to regenerate as it moved SE toward the disdrometer at the Agricultural Test Station.
		The last leg starting at 2101 UTC passed roughly 2 nm E of the disdrometer which was no longer in the heavy core.
		Because of uncertainty in the performance of the new AOC crew members and the desire to take it easy on this first mission, my leg selection and mission planning were very tentative and conservative on the first system flown, resulting in little heavy rain sampled.
	www.aoml.noaa.gov /hrd/96mission/FlaBay1.html (1320 words)

	NASA Disdrometer data from TRMM/LBA
		During LBA, one Joss-Waldvogel disdrometer, two 2-dimensional video disdrometers, and 11 APL disdrometers were operated.
		The NASA TRMM Office operated the video disdrometer at the airport during the period January 22 to February 24, 1999; however, data were not collected contiguously during that time.
		APL disdrometer data indicated saturation at the high end during heavy rainfall.
	daac.gsfc.nasa.gov /fieldexp/TRMM_FE/lba/nasa_disdrom.shtml (354 words)

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