In recent years, the deployment of X-band weather radars for dedicated applications such as gap-filling radars in complex terrain is considered by radar meteorologists and hydrologists. However, X-band weather radar observations suffer from the significantly higher attenuation in rain compared to the S- or C-band radar observations used operationally by the meteorological services. One way to deal with the attenuation is the use of radar polarimetry. Within the Adriatic-IPA project called ADRIARadNet (ADRIAtic integrated RADar-based and web-oriented information processing system NETwork), two innovative low-cost X-band dual-polarization mini radar systems have been installed in the centre of Italy and fully tested during an experimental campaign named ADRIAX. A special focus of ADRIAX has laid on the automatic processing of radar data. In this respect, a dedicated radar algorithmic chain, able to process raw data, enhance their quality, extract from them accurate and useful hydro- meteorological products have been developed and applied to the new installations. This processing chain, called RAPP (Radar Advanced Polarimetric Processing) is aimed at providing real time quantitative precipitation estimation (QPE) and hydrometeor classification processing raw radar data with several algorithms which can be resumed in the following steps: i) the quality control, where the most interference and artifacts are removed by exploiting the textural spatial correlation of meteorological targets with respect to artifacts, ii) the partial beam blockage, where in the radar bins, which are partially shielded between 10% and 60%, the equivalent reflectivity factor measurements are modified by adding 1-4 dB depending on the degree of occultation, iii) the attenuation correction where is used a technique based on differential propagation phase, iv) the hydrometeor classification achieved through a Bayesian algorithm, v) the convective and stratiform regions identification, where two algorithms based one on spatial relations and the other on the use of membership functions are implemented and vi) the precipitation estimation carried out as last step by means the conversion of the reflectivity using a model mainly deterministic and derived from curve fitting or empirical interpretations. Measures from a relatively sparse raingauge network are used as a reference to quantify the accuracy of X-Band rainfall estimates on a set of rainfall events occurred during the experimental campaign. Despite some lower performance at longer ranges the preliminary results of ADRIAX campaign revealed that these two innovative X-band dual-polarization mini radar, show acceptable performance in terms of polarimetric measurements and accuracy of spatial variability of rainfall.
Using RAPP processing chain with low-cost dual-polarization X-band mini radars: improvements and application to Adriatic field campaigns
Mario Montopoli;
2016
Abstract
In recent years, the deployment of X-band weather radars for dedicated applications such as gap-filling radars in complex terrain is considered by radar meteorologists and hydrologists. However, X-band weather radar observations suffer from the significantly higher attenuation in rain compared to the S- or C-band radar observations used operationally by the meteorological services. One way to deal with the attenuation is the use of radar polarimetry. Within the Adriatic-IPA project called ADRIARadNet (ADRIAtic integrated RADar-based and web-oriented information processing system NETwork), two innovative low-cost X-band dual-polarization mini radar systems have been installed in the centre of Italy and fully tested during an experimental campaign named ADRIAX. A special focus of ADRIAX has laid on the automatic processing of radar data. In this respect, a dedicated radar algorithmic chain, able to process raw data, enhance their quality, extract from them accurate and useful hydro- meteorological products have been developed and applied to the new installations. This processing chain, called RAPP (Radar Advanced Polarimetric Processing) is aimed at providing real time quantitative precipitation estimation (QPE) and hydrometeor classification processing raw radar data with several algorithms which can be resumed in the following steps: i) the quality control, where the most interference and artifacts are removed by exploiting the textural spatial correlation of meteorological targets with respect to artifacts, ii) the partial beam blockage, where in the radar bins, which are partially shielded between 10% and 60%, the equivalent reflectivity factor measurements are modified by adding 1-4 dB depending on the degree of occultation, iii) the attenuation correction where is used a technique based on differential propagation phase, iv) the hydrometeor classification achieved through a Bayesian algorithm, v) the convective and stratiform regions identification, where two algorithms based one on spatial relations and the other on the use of membership functions are implemented and vi) the precipitation estimation carried out as last step by means the conversion of the reflectivity using a model mainly deterministic and derived from curve fitting or empirical interpretations. Measures from a relatively sparse raingauge network are used as a reference to quantify the accuracy of X-Band rainfall estimates on a set of rainfall events occurred during the experimental campaign. Despite some lower performance at longer ranges the preliminary results of ADRIAX campaign revealed that these two innovative X-band dual-polarization mini radar, show acceptable performance in terms of polarimetric measurements and accuracy of spatial variability of rainfall.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
