Saturn dark oval May 13th

[Quark]

Hi All,

Imaged Saturn last night in rather ordinary seeing but have resolved the NNTrZ dark oval.



The dark oval is mid way between the CM and the P limb. I also note a bright spot close to the CM in the NNTrZ. Both of these features are best seen in my R channel data, the seeing just wasn't good enough to resolve these features in RGB.

I have measured the dark oval to be at Lat +45.7 L3 38.8.



Have added this data point to my spreadsheet & drift chart and attached my drift chart.



I also note from my spreadsheet that the dark oval has drifted a complete rotation of Saturn between Jan 23rd 2013 and May 8th 2013 ( from an L3 of 53.3 to an L3 of 54.1) a period of 15 weeks. Therefore its drift rate over this 15 week period (105 days) has been 3.4 degrees/day.

Thanks for looking.


Regards
Trevor

[Shiraz]

excellent work Trevor.

That drift rate is quite high - it is similar to the original storm at about 28m/s isn't it? - could it be the result of the same (or related) disturbance still having an effect? The other question is, what is the dark stuff that is being dredged up - any ideas?

Really interesting stuff! regards Ray

[Quark]

Thanks Ray, the original GWS formed at about +33 degrees which is very close to a zonal wind minima (slightly South) where the zonal wind velocity was very low, approx 40m/s. As the GWS drifted North that zonal wind velocity dropped off even further, virtually reducing to 0/ms then gradually increased as it started to feel the effects of the adjacent jetstream.

At +42 degrees the zonal wind velocity is about 40m/s and then at about +47 degrees it will peak at about 150m/s before again reducing toward the next zonal wind velocity minima which is at about +55 degrees with a wind velocity of about 0/ms.

A drift rate of 28m/s is in fact very low. The dark oval or vortex that is now the left over fossil spawned by the incredible turbulence generated by the GWS, is not really dredging up anything.

The original GWS was the result of a massive electrical storm, deep within the atmosphere, that did dredge up incredible amounts of material from deep within the atmosphere. A spectrometer onboard Cassini detected elevated phosphine levels from the dredge up. Phosphine is normally found only deep within the atmosphere.

The band that we now see in the NNTrZ region is a band where the GWS storm has cleared away the clouds and we are looking deeper into a slightly warmer region. The dark oval or vortex that still survives is cooler than the surrounding and is no longer associated with any lightning or SED's. So far this year no SED's have been detected.

Of course, the zonal wind velocities outside of the EZ at Saturn fade into insignificance, compared with the zonal wind velocity of the EZ, where they approach the speed of sound.

Hope this answers your question Ray.

[Shiraz]

thanks Trevor - just what I wanted to know. regards ray