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Please use this identifier to cite or link to this item: http://hdl.handle.net/10805/2086

Title: QUANTITATIVE PRECIPITATION ESTIMATES FROM DUAL-POLARIZATION WEATHER RADAR IN LAZIO REGION
Authors: SEBASTIANELLI, STEFANO
Tutor: NAPOLITANO, FRANCESCO
RUSSO, FABIO
BALDINI, LUCA
Keywords: RADAR
RAIN-GAUGE
QPE
ADJUSTMENT FACTOR
BIAS
CALIBRATION
Issue Date: 3-Jun-2013
Abstract: Many phenomena (such as attenuation and range degradation) can influence the accuracy of rainfall radar estimates. They introduce errors that increase as the distance from the radar increases, thereby decreasing the reliability of radar estimates for applications that require quantitative precipitation estimation. The aim of the present work is to develop a range dependent error model called adjustment factor, that can be used as a range error pattern for allowing to correct the mean error which affects long-term quantitative precipitation estimates. A range dependent gauge adjustment technique was applied in combination with other processing of radar data in order to correct the range dependent error affecting radar measurements. Issues like beam blocking, path attenuation, vertical structure of precipitation related error, bright band, and incorrect Z-R relationship are implicitly treated with this type of method. In order to develop the adjustment factor, radar error was determined with respect to rain gauges measurements through a comparison between the two devices, based on the assumption that gauge rain was real. Therefore, the G/R ratio between the yearly rainfall amount measured in each rain gauge position during 2008 and the corresponding radar rainfall amount was calculated against the distance from radar. Trend of the G/R ratio shows two behaviors: a concave part due to the melting layer effect close to the radar location, and an almost linear increasing trend at greater distance. Then, a linear best fitting was used to find an adjustment factor, which estimates the radar error at a given range. The effectiveness of the methodology was verified by comparing pairs of rainfall time series that were observed simultaneously by collocated rain gauges and radar. Furthermore, the variability of the adjustment factor was investigated at the scale of event, both for convective and stratiform events. The main result is that there is not an univocal range error pattern, as it is also a function of the event characteristics. On the other hand, the adjustment factor tends to stabilize over long periods of observation as in the case of a whole year of measures.
URI: http://hdl.handle.net/10805/2086
Research interests: Implementazione di algoritmi (in linguaggi Matlab e Fortran) per la stima in real time della precipitazione ottenuta da mappe di riflettività raccolte da radar meteorologico polarimetrico. Confronti fra stime di pioggia radar e corrispondenti misure pluviometriche. Stime quantitative di precipitazione da radar meteorologico polarimetrico. Modelli di trasformazione afflussi-deflussi. Analisi del coefficiente di ragguaglio dei campi di precipitazione stimati da mappe di riflettività radar. Calibrazione di radar meteorologici e verifica della qualità delle misure.
Skills short description: Esperienza nella verifica della qualità delle misure effettuate da radar meteorologici, con particolare riguardo alla verifica della calibrazione. Esperienza nella elaborazione di grandi masse di dati da radar meteorologico polarimetrico per la stima della precipitazione e per applicazioni idrologiche, con particolare riferimento ai modelli di trasformazione afflussi-deflussi e alla stima del coefficiente di ragguaglio (ARF). Esperienza di programmazione in linguaggi Matlab e Fortran.
Personal skills keywords: Radar meteorologico, pluviometro
Stima di precipitazione, quantitative precipitation estimates
Calibrazione, bias
Coefficiente di ragguaglio
Modellazione afflussi-deflussi
Appears in PhD:INGEGNERIA IDRAULICA

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