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U. Dyudina, A. Del Genio (GISS, New York), C. Porco (Southwest Research Institute), J. Barbara (GISS, New York), ISS Team
Cassini observed lightning in the nightside images of Jupiter as bright spots several pixels across. This allows us to identify several large lightning clusters. Lightning observed on the nightside is associated with the 1000-km-scale bright clouds observed on the dayside before they moved into the shadow of Jupiter. Lightning, being a result of precipitation in convective storms, reveals the convective nature of these clouds. The brightest lightning storm seen by Cassini is located in the Great Red Spot (GRS) wake. Convective clouds in the GRS wake usually survive for several days and then get sheared in the atmospheric flow. Cassini observed lightning in the GRS wake storm in two frames separated by 20 hours. It shows that the lightning activity and therefore strong convection lasts during substantial fraction of the cloud's lifetime.
The multiple flashes covering large area show that convection covers large area. This may indicate that the convection there is triggered by the atmospheric flow disturbance in the GRS wake. The size of the storm would be similar to the size of the atmospheric flow eddies. This is what we see in the ISS lightning images.
We will discuss energies of the lightning, atmospheric level where lighting occurs, and possible strategies for future lightning detection on Jupiter and Saturn.
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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.