How did ESA measure Steve's temperature using the SWARM spacecraft? Please explain how the measurement is really done, don't just mention an instrument's acronym.
I did a quick dump of TLEs for Satcats
39453, and estimated their semimajor axes and then altitudes and got the plot below, to double check that SWARM hasn't dipped down to 300km.
All of the reports mention that Steve's ion temperature is 3000C.
This ESA News Release says:
Prof. Donovan said, “As the satellite flew straight though Steve, data from the electric field instrument showed very clear changes.
“The temperature 300 km above Earth’s surface jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s compared to a speed of about 10 m/s either side of the ribbon. (emphasis added)
How did one or more of the three SWARM spacecraft above 440km measure the plasma temperature of Steve?
See more about Steve in this question.
Seven things to know about Steve: http://blog.aurorasaurus.org/?p=449
We are are still learning more about Steve, but here are seven things we think we know so far:
Steve appears ~10-20° (in latitude) closer to the equator (south in the Northern hemisphere) than where the normal green aurora is overhead. This means it could be overhead at latitudes similar to Calgary, Canada.
Steve is a very narrow arc aligned East-West and extending for hundreds or thousands of miles.
Steve emits light in mostly purple-ish colors. It is quite faint but is usually photographed with 5-10 second exposures.
Sometimes, it is accompanied by a rapidly evolving green short-lived picket fence structure.
Steve can last 20 min or even longer.
Steve appears to have a season. For instance, it has not been observed by citizen scientists from October 2016 to February 2017.
This phenomena has been reported from the UK, Canada, Alaska, northern US states, and even New Zealand.
more? (they used to call it a proton arc for lack of a better name. It isn't one!) http://spaceweathergallery.com/index.php?title=proton
Opening of SWARM and CryoSat Science Meeting - Extremely Interesting, Eric Donovan talking about how Steve was "discovered by scientists" by listening to amateur astronomers and aurora photographers who had been watching it for a while! Start to talk about Steve after
Thanks to @Roger's information here here is an ESA link for the video of the talk. (same time code)
Also, here is some amazing footage!