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)

Dieter R Poelman,Wolfgang Schulz

doi:10.5194/amt-13-2965-2020

Abstract

Abstract. The Lightning Imaging Sensor (LIS) on the International Space Station (ISS), hereafter referred to as ISS-LIS, detects lightning from space by capturing the optical scattered light emitted from the top of the clouds. The ground-based European Cooperation for Lightning Detection (EUCLID) makes use of the low-frequency electromagnetic signals generated by lightning discharges to locate them accordingly. The objective of this work is to quantify the similarities and contrasts between these two distinct lightning detection technologies by comparing the EUCLID cloud-to-ground strokes and intracloud pulses to the ISS-LIS groups in addition to the correlation at the flash level. The analysis is based on the observations made between 1 March 2017 and 31 March 2019 within the EUCLID network and limited to 54∘ north. A Bayesian approach is adopted to determine the relative and absolute detection efficiencies (DEs) of each system. It is found that the EUCLID relative and absolute flash DE improves by approximately 10 % towards the center of the EUCLID network up to a value of 56.3 % and 69.0 %, respectively, compared to the averaged value over the full domain, inherent to the network geometry and sensor technology. In contrast, the relative and absolute ISS-LIS flash DE over the full domain is 48.4 % and 71.3 %, respectively, and is somewhat higher than the values obtained in the center of the EUCLID network. The behavior of the relative DE of each system in terms of the flash characteristics of the other reveals that the greater the value, the more likely the other system will detect the flash. For instance, when the ISS-LIS flash duration is smaller than or equal to 200 ms, the EUCLID relative flash DE drops below 50 %, whereas it increases up to 80 % for ISS-LIS flashes with a duration longer than 750 ms. Finally, the distribution of the diurnal DE indicates a higher DE for the ISS-LIS and a lower DE for EUCLID at night.

Highlights

Lightning processes in the cloud and from cloud to ground involve the formation of channels carrying tens of kiloamperes of electric current with temperatures as high as 30 000 K
Surprisingly, the highest IC : CG ratios are found in regions where the baseline between LS700x sensors is small and drops off towards the south and east of the domain where mainly IMPACT sensors were installed during the period of investigation
The mean IC : CG flash ratio in the center of the network is comparable to the values observed by the U.S National Lightning Detection Network (NLDN) in various parts throughout the contiguous United States as presented by Medici et al (2017)

Summary

Introduction

Lightning processes in the cloud and from cloud to ground involve the formation of channels carrying tens of kiloamperes of electric current with temperatures as high as 30 000 K. Those processes are accompanied by intense radiation in the optical frequency range with the peak power typically being of the order of 109 W (Christian et al, 1989). These optical emissions are a result of dissociation, excitation, and subsequent recombination of various atmospheric constituents as a result of the sudden intense heating, and they primarily occur at discrete atomic lines. In 1995 the OV-1 (MicroLab 1) satellite carrying the Optical Transient Detector (OTD) was launched, fol-

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