Monthly Archives: September 2016

Lidar

It was lightly snowing last night, ice crystals falling from high, thin clouds as I walked from the Big House to the Green House. Looking towards the MSF there was just enough ice in the air to illuminate the ICECAPS LiDAR – a laser measuring cloud matter, phase, and crystal orientation. ICECAPS is a relatively large, long-term project researching cloud characteristics and their impact on climate. This knowledge is crucial in developing climate models as well as understanding our changing climate. More information can be found here: www.esrl.noaa.gov/arctic/observatories/summit.

Most of the time the laser is invisible, however with just the right conditions enough light can be reflected back to show the brilliant green beam. If you look carefully you can also see the vertical laser, however this is weaker and thus less visible. Beautiful science!

*If you are familiar with LiDARs you may have seen this spelled LIDAR, lidar, LiDAR, or LADAR – according to NOAA’s Digital Coast Blog all spellings are correct though LiDAR is gaining in popularity. 

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The ICECAPS LiDAR here at Summit

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The LiDAR at NOAA’s ARO facility at the South Pole Station

 

An example of the LiDAR data:

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Halos

Auroras may grace the polar skies at night, but the day sometimes brings phenomenal halos and sundogs. It’s hard to describe the intangible beauty of these phenomena – vibrant spots of rainbow on either side of the sun, glowing pillars of light from the sun, a brilliant stream of light encircling the sky parallel to the horizon…a good display is simply awe-inspiring.

In general atmospheric optical phenomenon (sundogs, halos, rainbows) are not uncommon. Frequent halos and sundogs can be seen around the world when ice crystals in the atmosphere reflect and refract light. Infrequent halos are more often seen in polar regions or at high elevations with colder temperatures and more ice in the atmosphere. A common occurrence with halos is “Diamond Dust” which is essentially a ground level ice cloud filling the air with glittering ice crystals.

All photos below were taken by me, click on any of the images to open the full photo with caption.


The different crystal shapes generate different optics, however ice crystals form in hexagonal symmetry, thus while the crystal might be long or short (columnar or plate-like) the internal angles are always the same. Here at Summit the ICECAPS project, housed primarily in the MSF, is researching these crystals and cloud formations to better understand the complex processes involved in these systems.

The following website is a brilliant source of information regarding atmospheric optics and identifying features: www.atoptics.co.uk. An impressive full list of optical phenomenon can be found here: https://wikipedia.org/Atmospheric_optical_phenomena. For more Summit specific photos and information check out the Polar Field Services blog, Field Notes.

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Photograph of a good halo display – 22° halo, upper tangent arc, 46° halo, and parhelic circle at Summit Station, Greenland

 

Below are some of my favorite photos of optics that I have witnessed in the Arctic and Antarctic. If only I’d had my wide angle lens in past seasons! Click on images to bring up caption and full picture.

 

According to atoptics.co.uk, 120° parhelia are infrequent, but not super rare. They are often faint and short lived however, I have only ever seen them twice. Below is a panorama at Summit showing bright 120° parhelia.

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Bright sundogs, 22° halo, and definite rare 120° parhelia! (Summit)

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Looking opposite the previous photo – the 120° parhelia can be seen along the parhelic circle (Summit)

Moon halos are not uncommon either, but require a nearly full moon and darkness as well as halo forming conditions.

 

Other interesting optical phenomena include the green flash and fogbows. The green flash lasted a few hours at the South Pole Station in 2013 (check out my post from that sunset with more green flash photos here). This photo was taken through a telescope. It’s a bit blurry due to heat waves and light distortion near the horizon, the same process which causes the green flash to be visible. Fog and fogbows are a frequent occurrence at Summit, Greenland.

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 Happy belated equinox and sunrise at Pole!

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Autumn

It is autumn on the ice sheet; Nights are growing longer and darker, days ever slightly colder, the winds are variable and often brisk. We often have freezing fog and rime grows on everything.

It’s been a month since the last plane departed from Summit Station and the five of us have settled into our roles and routines. The two science techs monitor the year-round science on station, troubleshooting issues, launching weather and ozone balloons, conducting accumulation surveys, and GPS measurements to calibrate ICEBridge data. The Mechanic keeps our lights on and water running – but he is also busy catching up on all the little projects from summer, tuning up snowmobiles, winterizing equipment, and cleaning the shop. Our heavy equipment operator has put the CAT D7 bulldozer to work completing the winter berm and pushing snow away from the station buildings. He’s made significant progress, but there is an infinite amount of snow and he’ll be busy until his last day here. As the station manager I have familiarized myself with the station and all the little changes that have occurred in the last year. I do all the admin/paperwork/email for the station as well as lead up safety and communications. This past month I’ve put my heavy equipment skills to work in the loaders cleaning up station, consolidating cargo, placing items on the winter berm, and doing water runs.

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Mostly we’ve been busy preparing for winter – making sure everything is up above grade, flagged, and photographed. We’ve winterized the summer buildings and moved them up to the berms. Air vents are covered, windows and doors secured, everything that shouldn’t freeze has been moved inside. Heavy equipment that won’t be used through the winter is parked up on berms, the air intake and exhaust taped up, the batteries disconnected and moved inside.

The station is nice and quite with just 5 people. While the summers are exciting and non-stop, the winters are slow and steady with time to catch up on projects. The summer professional cook is missed, however everyone takes turns cooking now and it’s fun. If nothing else, we’re burning so many calories in the cold and altitude that everything tastes good!

We’ve had a lot of overcast and cloudy days this month, though we’ve also had a few amazing sundogs and other atmospheric optics – more on that in my next post. Temps have dipped down to the -30F range, but our average day is around 0F to -10F with 10kt winds.

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A fog bow above station

Summit Station is at 72°N. For comparison Barrow, AK is at 71°N, Eureka Nunavut is at 79°N, Reykjavik Iceland is at 64°N, Longyearbyen Svalbard is at 78°N, and McMurdo Station in Antarctica is 77°S.

At 72°N we’ll have two and a half months (10 weeks) of 24 hour darkness, but unlike at the South Pole where there is one long day and one long night, we do have some day and some night for most of the year. In mid-August when the last plane left the sun was rising at 0305 and setting at 2205. Today it rose at 0555 and will set at 1857.

Below is a graph showing sunrise/sunset times for Summit in 2016 (note: times will shift one hour back in Oct for daylight savings)

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