Surface density of lightning discharges on Jupiter as a function of their energy

Detection of lightning discharges on Jupiter and the estimation of their energy have been the subject of numerous studies using data from variety of spacecraft and probe instruments, operating mostly in the optical range. Individual datasets, however, report markedly different numbers of detected events and characteristic energies, largely due to differences in sensitivity, accumulation time and spatial coverage of individual instruments.

To provide a more unified view of optical lightning observations made by Voyager 1&2, Galileo, Cassini, New Horizons and Juno SRU, we use lightning density evaluated on the visible surface as a common metric. By dividing the energy range into logarithmically spaced bins, we compute the lightning density within each interval. This approach enables a direct comparison between instruments with different sensitivities and reveals a consistent log-normal distribution of lightning energies across multiple datasets.

Detections of lightning-generated whistlers on Jupiter by the Juno mission are substantially more prevalent than all previous optical detections. Unlike optical observations, the sensitivity of radio measurements is not constant. It varies by several orders of magnitude depending on the spacecraft’s position and local plasma conditions, complicating detection statistics.

We introduce also a method to estimate the minimum detectable whistler energy in individual Juno Waves LFR-Lo snapshots. The method is based on modeling the background incoherent noise, including both instrumental and natural contributions. Artificial whistler waveforms with known properties are injected into the modeled noise to test detectability and to evaluate the performance of the Poynting vector measurement.

By this approach, we are able to compare lightning density as a function of energy for both optical and radio wavelengths.