Concurrent satellite and ground-based lightning observations from the Optical Lightning Imaging Sensor (ISS-LIS), the low-frequency network Meteorage and the SAETTA Lightning Mapping Array (LMA) in the northwestern Mediterranean region

Abstract

Abstract. The new space-based Lightning Imager (LI) onboard the Meteosat Third Generation (MTG) geostationary satellite will improve the observation of lightning over Europe, the Mediterranean Sea, Africa and the Atlantic Ocean from 2021 onwards. In preparation for the use of the upcoming MTG-LI data, we compare observations by the Lightning Imaging Sensor (LIS) on the International Space Station (ISS), which applies an optical technique similar to MTG-LI, to concurrent records of the low-frequency (LF) ground-based network Meteorage. Data were analyzed over the northwestern Mediterranean Sea from 1 March 2017 to 20 March 2018. Flashes are detected by ISS-LIS using illuminated pixels, also called events, within a given (2.0 ms) frame and during successive frames. Meteorage describes flashes as a suite of intra-cloud and cloud-to-cloud (IC) pulses and/or cloud-to-ground (CG) strokes. Both events as well as pulses and strokes are grouped to flashes using a novel in-house algorithm. In our study, ISS-LIS detects about 57 % of the flashes detected by Meteorage. The flash detection efficiency (DE) of Meteorage relative to ISS-LIS exceeds 80 %. Coincident matched flashes detected by the two instruments show a good spatial and temporal agreement. Both peak and mean distances between matches are smaller than the ISS-LIS pixel resolution (about 5.0 km). The timing offset for matched ISS-LIS and Meteorage flashes is usually shorter than the ISS-LIS integration time frame (2.0 ms). The closest events and the pulses and strokes of matched flashes achieve sub-millisecond offsets. Further analysis of flash characteristics reveals that longer-lasting and more spatially extended flashes are more likely detected by both ISS-LIS and Meteorage than shorter-duration and smaller-extent flashes. The ISS-LIS relative DE is lower for daytime versus nighttime as well as for CG versus IC flashes. A second ground-based network, the very high-frequency (VHF) SAETTA Lightning Mapping Array (LMA), further enhances and validates the lightning pairing between ISS-LIS and Meteorage. It also provides altitude information on the lightning discharges and adds a detailed lightning mapping to the comparison for verification and better understanding of the processes. Both ISS-LIS and Meteorage flash detections feature a high degree of correlation with the SAETTA observations (without altitude information). In addition, Meteorage flashes with ISS-LIS match tend to be associated with discharges that occur at significantly higher altitudes than unmatched flashes. Hence, ISS-LIS flash detection suffers from degradation, with low-level flashes resulting in lower DE.

Comparing lightning observations of the ground-based European lightning location system EUCLID and the space-based Lightning Imaging Sensor (LIS) on the International Space Station (ISS)

“…In this paper EUCLID and ISS-LIS lightning observations are correlated using data from 1 March 2017 until 31 March 2019 as observed within the EUCLID domain and limited to 54 • north. The ISS-LIS detects optically bright discharges, such as return strokes and in-cloud discharges inducing a rapid change in the electric field (Goodman et al, 1988). Those rapid changes in the electric field are exactly the features detected by EUCLID.…”

“…An extra region is outlined in Fig. 7 covering Corsica, corresponding with the region investigated by Erdmann et al (2020) in which ISS-LIS flashes are matched against those observed by the ground-based Météorage network during an approximately 1-year period from 1 March 2017 until 20 March 2018. Applying analog flash matching criteria as in Erdmann et al (2020) over the Corsica area, i.e., strokes and pulses are matched to ISS-LIS groups using a 1.0 s temporal and 20 km spatial criterion, P (ISS-LIS|EUCLID) becomes 59.7 % in this study, which is similar to the 62.4 % found in Erdmann et al (2020).…”

“…The large rectangle highlighted in white is the self-defined center of the EUCLID network in Fig. 3, whereas the smaller white rectangle highlights the area used in Erdmann et al (2020) against which the results in this paper are compared to. LIS) being 82.9 %.…”

“…In April 2013 it was decided that an LIS, built as the flight spare for the TRMM satellite, should be put on the International Space Station (ISS), and almost 4 years later (March 2017) the instrument started recording data. The data of this sensor, called the ISS-LIS, were analyzed in Erdmann et al (2020) for the time period March 2017 to March 2018. They compared for the first time, although in a small part of Europe, ISS-LIS data to the low-frequency LLS data of Météorage and the lightning mapping array SAETTA (Coquillat et al, 2019) over the northwestern Mediterranean Sea near Corsica.…”

“…They compared for the first time, although in a small part of Europe, ISS-LIS data to the low-frequency LLS data of Météorage and the lightning mapping array SAETTA (Coquillat et al, 2019) over the northwestern Mediterranean Sea near Corsica. In this paper the performance of EUCLID (European Cooperation for Lightning Detection), a groundbased LLS similar to the LLS of Météorage, will be evaluated against ISS-LIS data over an extended time period and a larger area in Europe as compared to Erdmann et al (2020). This work is timely given that the Meteosat Third Generation (MTG), which has a Lightning Imager (LI) on board, will probably be launched in 2021.…”