[X] My Assistant

[ngunn]

Titan weather studies feature large in plans for the November encounter. From the latest 'looking ahead':

Outbound, VIMS will control pointing, mapping Titan's surface and cloud features. ISS will take images during this flyby by riding along with other instruments' observations, so no large mosaics are planned. The ride-along images should be useful for cloud monitoring, and if present, the clouds' motions and development can be tracked. The area will have been covered by the October 29 distant observation for comparison. Follow-up observations on November 13 and 14 will allow researchers to track clouds in the two days following the encounter. These will also cover the area that was under the arrow storm a month and a half earlier. An important goal will be to detect signs of surface changes that resulted from flooding caused by the storm's torrential rains.

[nprev]

Re rain detection: Any indication that they might try to do so?

I'd imagine that radar would be the only possible way to do this; there should be a pronounced attenuation of both the inbound & outbound pulses if they pass through a rainstorm.

It'd be a tough observation to get, though. You'd have to specifically target a suspected storm system, and I don't know if they can reshuffle an encounter timeline rapidly enough to react to storm formation.

Still, might be worth it. We could learn something useful about the composition of the rain; mostly methane, of course, but undoubtedly there would be trapped aerosols & other compounds as well that would modify its radar attenuation properties.

[rlorenz]

Re rain detection: Any indication that they might try to do so?

I'd imagine that radar would be the only possible way to do this; there should be a pronounced attenuation of both the inbound & outbound pulses if they pass through a rainstorm.

It'd be a tough observation to get, though. You'd have to specifically target a suspected storm system, and I don't know if they can reshuffle an encounter timeline rapidly enough to react to storm formation.

Still, might be worth it. We could learn something useful about the composition of the rain; mostly methane, of course, but undoubtedly there would be trapped aerosols & other compounds as well that would modify its radar attenuation properties.

It would be difficult to detect rain unambiguously via attenuation - you'd need a very well-characterized
target. However, one can detect backscatter from rain, although to do so with any sensitivity
you need to work near closest approach, and have to crank up the gain such that the surface echo is
saturated and useless for geomorphology. I reported on our first attempt some while back
http://www.lpl.arizona.edu/~rlorenz/precip.pdf

We likely wouldnt learn anything about the composition, but particle size and number density.

We continue to make occasional measurements like this - an obvious target is the northern polar regions in
summer where we might expect storms.