Cyclone-related lightning near Juno's 6th orbit
Abstract
The densest cluster of Juno MWR lightning strikes on perijove 6 (PJ6) occurred near 49 N planetographic latitude (Brown et al. 2018; DOI:10.1038/s41586-018-0156-5). Hubble imaging reveals a cyclonic vortex at this location.
Assuming the results of Romps et al. (2014; DOI:10.1126/science.1259100) apply to Jupiter as well as the Earth, Jupiter's cyclones are likely to be heavily-precipitating systems, explaining observations of depleted volatiles in microwave spectral imaging data (de Pater et al. 2016; DOI:10.1126/science.aaf2210). Ground-based thermal infrared imaging and spectra show that anomalies in temperature, composition, and cloud structure are common in low-latitude cyclonic vortices of different types. These infrared data were acquired in early 2017 using VLT/VISIR, Gemini NIRI, Keck NIRSPEC, and IRTF iSHELL. Hubble imaging data constrain some clouds to be deeper than 4 bar (presumably water clouds), particularly in the PJ6 cyclone with strong lightning activity. Large cyclones feature differences in high-altitude particle properties relative to their surroundings, consistent with downwelling and sublimation of haze particles in the upper troposphere. Warm, dry, and less-hazy conditions in the upper part of cyclones are consistent with downwelling aloft, while deep water clouds and lightning are consistent with upwelling at depth, precisely the inverse of the circulation within anticyclonic vortices according to Marcus et al. (2013; DOI:10.1115/1.4007666). This vortex structure suggests that midplanes of cyclones with lightning activity lie between the upper troposphere and the water cloud layer. Cyclones without water clouds and lightning may exist if their midplanes lie deeper than the water cloud layer.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P33F3891W
- Keywords:
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- 5704 Atmospheres;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5739 Meteorology;
- PLANETARY SCIENCES: FLUID PLANETSDE: 5754 Polar regions;
- PLANETARY SCIENCES: FLUID PLANETSDE: 6220 Jupiter;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS