On the infrasound array monitoring in Romania: reprocessing of the data recorded by the national infrasound network

We present the results of the reprocessing a 10-year archive of waveform data recorded with the Romanian infrasound network, by using PMCC signal detector. Starting with 2009, three infrasound stations have been deployed on the Romanian territory by the National Institute for Earth Physics (NIEP): IPLOR 6-element array of 2.5 km aperture, in the central part of the country, BURARI 4-element research array of 1.2 km aperture, in the northern Romania, under the cooperation with Air Force Technical Application Center AFTAC (USA), and I67RO – a temporary PTS portable 4-element array of 0.9 km aperture, in western Romania, for two-year experiment (2016-2018), within a collaboration project with PTS/CTBTO. In 2019, BURARI station has been upgraded to 6-element array with a 0.7 km aperture.

Infrasound data are processed and analyzed on routinely basis at NIEP by using a duo of infrasound detection-oriented software – DTK-GPMCC and DTK-DIVA – packaged into CTBTO NDC-in-a-Box. Since October 2019, a new implementation of PMCC algorithm is available at NIEP, enabling the characterization of the coherent infrasound field in log-spaced frequency with one-third octave bands from 0.1 to 7 Hz. The full data set recorded with the Romanian infrasound stations has been reprocessed by applying the new PMCC algorithm.

The array monitoring performance resulted after the data reprocessing is investigated. Detection capability assessment, types of sources observed, as well the capacity of fusing the detections into support of understanding various infragenic sources are presented. A better characterization of the detected signals in the frequency-azimuth space or frequency trace-velocity space is clearly observed. Infrasonic signals generated by several relevant sources detected with the three arrays deployed on the Romanian territory are shown.