Wednesday, July 31, 2013

Sprites 2013: Update #2


We flew again the other night. The storm, over much of the Oklahoma / Missouri / Arkansas area, was massive and producing a ton of lightning.

Hans and Ryan looking at weather data and planning a course before takeoff.

We took off and headed that way, but cut a corner too close and got stuck in the cirrus clouds, unable to see either stars in the sky or cities on the ground. Just a black void out the window. After turning south and flying for a while, we came into clear air, cut north and ran up the east side of the storm through western Tennessee. At this point, after wasting ~2 hours of flight time, we started seeing a few sprites, and managed to record 11 on high speed with spectra. Not bad, but not really that good either. At least it was something.

Me sitting in the trigger seat with the log in my lap and my thumb on the trigger.

Later on, I saw a bright meteor - or at least it was bright on the low light camera. I trigger the high speeds so we got spectra of the meteor as well. Totally unrelated to what we were doing, but neat anyway. Also, while sitting and watching the screen for sprites, I watched a pixel die and become 'hot'. I've never seen that before.

Last night the weather was unpromising so we stayed on the ground and fixed an issue with light leaks: The dark cloth we had attached around the windows to keep reflections out of the cameras wasn't working too well. So we hung some new dark cloth which I think is a much better design, and that has nothing to do with the fact that I designed it. We then finished up the night by walking into a bar 10 minutes before close (at midnight... : / )

Weather looks dull tonight and tomorrow too, my guess is we won't fly tonight and will call a down day tomorrow so we can be ready to fly anytime this weekend, when the potential for big storms increases again.

Monday, July 29, 2013

Sprites 2013: Update #1

We took our first flight the other night, but the weather was uncooperative. The storm we went to fly was unproductive, and high cirrus clouds with us up at 45,000 feet were bright enough in the near-full moonlight that we couldn't even turn the image intensifiers on for a while. So we basically treated it as a shakedown flight and went through the motions, found a few kinks in the system, and spent the next night in the hangar ironing them out. We should be ready for business now.

Our aircraft is NCAR's Gulfstream V, which is just a fantastic aircraft. I want one.

In the hangar.

On the tarmac.

Inside, we have a bunch of electronics set up with seating positions for the five scientists plus an aircraft tech. And pilots, can't forget those. From front to rear, the science positions are:

1. Trigger man. This is the person who triggers the high speed camera when they see a sprite. It's a job for someone with good eyes and fast reactions, so it's where I'm sitting. I basically watch a monitor with my thumb on a trigger, and when I see a sprite in the Phantom field of view I hit the button which triggers both Phantoms to record, and yell 'Sprite!' into the headset/comms so everyone knows what just happened. At the speed we're running the Phantoms I have about 1 second in which to recognize a sprite in the field of view and hit the button. Then while the Phantoms are writing to permanent memory I record our position, heading, camera elevation/azimuth and settings into a logbook.

2 and 3. Camera operators. Their job is to physically point the cameras and to save the data after I trigger. Both of these positions have a Phantom high speed camera, running at 10,000-15,000 frames per second, on a mount facing out the window. The Phantoms have image intensifiers in front of them to be able to film low light events at such high speeds. These intensifiers are so sensitive they can be ruined by looking at the Moon, or even moonlight reflecting off a cloud, turning a ~$20,000 piece of equipment into a paperweight. In front of the intensifiers are standard Nikon F-mounts with fast 50mm Nikon lenses. The forward camera additionally has a diffraction grating in front of the lens so it can capture sprite spectra, the main focus of this campaign. There are also a few Watec 'context' cameras recording at 30 frames/second (err, 60 fields/second, but who's counting?) These context cameras have a wider field of view than the Phantoms and help us locate sprites and point the Phantoms in the right spot. One of the Watecs is what I watch on my monitor at the trigger station.

Forward camera position. The yellow cloth is to prevent light from inside the cabin reflecting off the window and into the lenses.

The mounts are really cool. On the campaign with NHK in 2011 we just strapped $10,000 television tripods against the wall, which sounds impressively expensive but doesn't work that well: The heads were unlevel so we had field rotation when moving the cameras in azimuth, and the axis of rotation was through the camera so the lens moved a lot when you panned, sometimes causing you to be looking at the side of the aircraft window rather than outside. These mounts are solid, level, and the rotation axis is right in front of the lenses so the lenses don't really move when you pan the camera. Awesome.

4. Sprite finder. This position has monitors displaying all the Watec cameras, and the job here is to pay attention to all of the monitors for sprites, then tell the camera operators where to point the cameras.

'Finder' seat on left, mission coordinator seat on right.

5. Mission coordinator. A computer on which the operator can call up all kinds of weather and lightning data in real time, plan where we should be flying, and inform the pilots.

Hans, Geoff, and Ryan discussing the weather data in the middle of a flight.

It occurs to me that the only position I don't have a picture of is my position. I'll try to rectify that soon.

Rocky Mountain National Park

For the sprites campaign, we're only allowed to work a maximum of 6 days in a row, then we have to shut down operations for crew rest. Yesterday was our first such hard down day, so I took the opportunity to visit Rocky Mountain National Park and do a little hiking. I looked briefly at the website and decided I wanted to try and climb (or at least wander around nearby) Mount Chapin, a ~12.5 thousand foot summit in the southern Mummy Range. So I drove to RMNP and up the Old Fall River Road, which was pretty cool itself, and set out at the trailhead.


The website warned that the trail was poorly maintained and difficult to follow, but I actually found it pretty obvious and easy. I guess I'm just used to interior Alaska, where half the time there's no trail at all and you're just wandering about. From the parking area you climb up to a pass, then instead of descending the other side, you turn and start heading upwards. You come out of the trees pretty soon and it's all alpine meadows and scree slopes from there.

Hills and stuff

The parking area is around 11,000 feet. Both the Arkansas River Valley and the Tanana Valley are near sea level, so that's what I'm used to. Consequently, the altitude was kicking my butt on the uphills, so I took it nice and slow. Plus, I'm in no real hurry and have no particular destination, so why not take it easy? And the weather was great: ~70% could cover kept the direct sunlight off most of the time, and a stiff wind made it quite cool - enough to put a bite in the tips of my ears once or twice. Marvelous. It was amusing to be walking around in a thin t-shirt while everyone else had fleece jackets zipped up against the wind.

I have a tendency to not look at maps very closely before I go hiking. This is a double edged sword. On one hand, it reinforces the 'no particular destination' idea, and I spend more time wandering and enjoying where I'm at rather than focusing on where I'm going. On the other hand, it often ends up with me not really knowing exactly where I'm at. So it turns out I walked right past Mount Chapin and up the wrong mountain before I realized it. You wouldn't think accidentally walking past a mountain is something that's likely to happen, but there you go. I even surprise myself sometimes.

So, approaching the 12,500 13,000 foot summit of Mount Chapin Chiquita, I could see some low, grey overcast clouds on top. But I had been watching them for the last hour or so of approach, and the situation seemed to not be changing much; it looked like an orographic effect rather than a gathering storm. So I decided it was probably stable and safe to head on up. On top of Mount Chiquita I was just high enough to be in the bottom of the clouds, and it was rather chilly.


I found a sittin' spot

Heading back the way I came, I noticed a trail further down the mountain that looked much less rocky and side-slopey than the one I was on, and thus faster. With a strong suspicion that it went to the same place, I decided to descend the ~500 feet and try it. Right about the time I made the lower trail, I noticed a small herd of elk, perhaps 10 or 15 strong, in the valley below, with a single passing sunbeam about to illuminate them for a brief moment. I threw my bag down and barely dug out my 150mm lens in time to capture this, which ended up not really being that great anyways, but c'est la vie.


Back at the car, I noticed the main valley was filling with mist, so I stopped to grab the last picture of the night at the lava cliffs overlook.


Monday, July 22, 2013

Begin: Sprites campaign

I've been thinking about starting to update this blog again for a while now, but I never really know where to start. So I'm just going to start. If history is any guide, I'll give up on it again soon, but we'll see.

Today I started another sprites observing campaign. Similar to the campaign I worked two years ago with NHK, we'll be flying above thunderstorms in a Gulfstream, using intensified high speed cameras to capture videos of sprites at 10,000 frames per second. In that campaign we were focusing on 3 dimensional reconstruction via filming a sprite from two different locations; this time we're after high resolution spectra of the sprites. I may go into more detail in a future post, but the take home message is we're only flying one aircraft. Today we did an electromagnetic interference test where we rolled the plane out on the tarmac, fired up all the electronics as if we were taking data, and let the pilots test the avionics for interference. Apparently we passed, so we're ready to fly. We may do a short flight Thursday or Friday, but due to the Moon being almost full, our real opportunities start next week. The Gulfstream belongs to NCAR RAF (National Center for Atmospheric Research's Research Aircraft Facility - the same folks who fly through hurricanes) and we're flying out of their base at Rocky Mountain Metropolitan Airport, just outside Boulder, CO.

So being that it just started today, I don't have much to write yet. But here are a couple of pictures from recent months, taken by other people, that I thought were really cool. First:


This image, taken in May, is probably the first ever image of a sprite and an aurora together. But then, only a week or so later, came another one:


I don't really have anything to add. I've never captured a sprite with my own camera, but I'm going to give it a shot during this campaign.