Pludix is an X-band disdrometer based on the Doppler effect, that provides rainfall intensity and drop size distribution output, and exhibits potential capabilities as a Present Weather Sensor (PWS). A Present Weather Sensor is an instrument capable of automatically detecting weather phenomena present at the time of observation. In order to verify the latter, two different methods have been developed to identify the precipitation types according to the WMOcodes in its table 4680. With the first method (P-method), twelve precipitation codes are identified by analysing the characteristics of the Pludix power spectrum. With the second method (S-method), a statistical one based on a pattern recognition type algorithm, twenty- three precipitation codes are identified. With both methods main precipitation types are identified: drizzle, rain, snow, hail, ice crystals, mixed precipitation. Pludix is compared with the reference observations of a human observer during a campaign performed at the weather station of Wasserkuppe (central Germany, 950 m a.s.l.). Two years of data are analysed (December 2000–January 2003); in this time interval there was a fair amount of both liquid and solid precipitation events, allowing us to evaluate the instrument capabilities. Pludix is also compared with the Vaisala FD12P PWS and with the optical disdrometer Parsivel which were tested in the same campaign. Since the S-method has only recently been developed and it is under investigation, the present analysis is mainly focusing on the P-method. The results show that Pludix performs quite well in distinguishing the precipitation type and it is generally in agreement with the human observations, especially for the rain case. Pludix also detects some situations (especially rain-showers with hail) that the human observer sometimes does not detect. The instrument is less sensitive to the slight precipitation, especially because it samples on a small measurement volume. We also test the performance of Pludix in measuring the rainfall-intensity, finding that it works better than the other instruments in the case of rain.
Comparative investigation of Pludix disdrometer capability as Present Weather Sensor (PWS) during the Wasserkuppe campaign
D'ADDERIO, Leo Pio;
2011
Abstract
Pludix is an X-band disdrometer based on the Doppler effect, that provides rainfall intensity and drop size distribution output, and exhibits potential capabilities as a Present Weather Sensor (PWS). A Present Weather Sensor is an instrument capable of automatically detecting weather phenomena present at the time of observation. In order to verify the latter, two different methods have been developed to identify the precipitation types according to the WMOcodes in its table 4680. With the first method (P-method), twelve precipitation codes are identified by analysing the characteristics of the Pludix power spectrum. With the second method (S-method), a statistical one based on a pattern recognition type algorithm, twenty- three precipitation codes are identified. With both methods main precipitation types are identified: drizzle, rain, snow, hail, ice crystals, mixed precipitation. Pludix is compared with the reference observations of a human observer during a campaign performed at the weather station of Wasserkuppe (central Germany, 950 m a.s.l.). Two years of data are analysed (December 2000–January 2003); in this time interval there was a fair amount of both liquid and solid precipitation events, allowing us to evaluate the instrument capabilities. Pludix is also compared with the Vaisala FD12P PWS and with the optical disdrometer Parsivel which were tested in the same campaign. Since the S-method has only recently been developed and it is under investigation, the present analysis is mainly focusing on the P-method. The results show that Pludix performs quite well in distinguishing the precipitation type and it is generally in agreement with the human observations, especially for the rain case. Pludix also detects some situations (especially rain-showers with hail) that the human observer sometimes does not detect. The instrument is less sensitive to the slight precipitation, especially because it samples on a small measurement volume. We also test the performance of Pludix in measuring the rainfall-intensity, finding that it works better than the other instruments in the case of rain.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
