Sunday, August 14, 2016

Terrestrial Sciences at Niwot Ridge, Colorado

Niwot Ridge (an hour and a bit away from Boulder, Colorado), has a long history of scientific research dating back at least 50 years. Today various entities such as the University of Colorado, which includes the Long Term Ecological Research (LTER) netrwork, NOAA, NEON and NRCS have observing equipment in the area. The ridge spans a range of ecotones, from forest up to alpine tundra. NCAR's Terrestrial Sciences Section and associated researches such as myself went up to Niwot to check out some of the data sources used for developing and improving the Community Land Model.


John talks about his strategy for measuring fluxes both above and below ground in the tundra zone


Various instruments on a portable flux tower
 
The flux tower, DFIR precipitation gauge and associated apparatus belonging to the National Ecological Observing Network (NEON).
 
Inside the University of Colorado's "Tundra Lab".


Sean exploring local hydrology heterogeneity in the tundra zone.


Will explains the new wireless network of sensors that are being installed in a transect across the alpine tundra. The "Tundra Lab" can be seen in the background


The large Ameriflux Tower at the Niwot forest site. Sensible heat, latent heat and carbon fluxes are measured at various levels, both above and below the forest canopy.


The equipment in this shed is used to record the isotopic ratios of carbon measured on the flux tower.


Rosie (center) and Danica (right) gave us a basic introduction to sap flow measurements


Rosie explaining how sap flow measurements work using heat flow meters (i.e. two spikes driven into the tree).


John discusses a number of snow measurements taking place within the forest. These include  measurements  of snow depth in relation to trees as well as experimental systems for quantifying interception of snow by the canopy.


Justin, John & Danica at the Niwot Ridge SNOTEL station during the snow-free season. The large item in the center of the picture is the pressure transducer pillow that measures snow water equivalent (SWE).


Saturday, July 16, 2016

Permafrost Tunnel and Super-Site

Permafrost, ground that is continually below 0C for two or more years, is a notable feature of the Arctic. The CRREL Permafrost Tunnel (drilled into a hillside) is a virtual time machine where ancient vegetation and fossils from long extinct animals can be easily seen entombed in the frozen ground. Ice wedges with an age of over a hundred thousand years are another amazing feature to be seen.

Many meters underground Misha K (with the flashlight) explains permafrost formation processes. We can see both the main tunnel and the offshoot tunnel (with yellow walkway)
Hands-on experience (literally) with vegetation entrapped in permafrost that is well over 10,000 years old

After being in the sub-freezing temperatures of the permafrost tunnel, everyone was ready for some sun at lunchtime


Next stop for the day was the Super-Site flux tower which has been operated by IARC for over five years. This tower measures the energy, mass and carbon balance of a Black Spruce forest and aims to distinguish how much the upper canopy and understory vegetation each contribute to various fluxes.


The Super-Site Flux Tower has various instruments all the way up the tower
Guo explains the instrumental set-up at the tower and answers questions about observational methods
Vladimir, Marc and Sophia observing and probing the very wet and thick moss layer
Mmm ... tasty blueberries direct from the Alaskan forest
Andrea, Danica and Charles return from the forest with a bounty of blueberries

A final stop was made at a section of the Trans-Alaska Pipeline System. This engineering feat transports oil all the way from the Arctic Ocean, across a full North-South transect of Alaska, to the port of Valdez on the Pacific Ocean.

The pipeline. The vertical silver items are cooling fins that form part of a thermosiphon (a device for keeping the adjacent ground cool so that permafrost does not thaw and damage the pipeline).





IARC Summer School 2016

Over my years of research I've probably visited University of Alaska, Fairbanks (UAF) more than any other campus - and I'm back again to help teach the IARC (International Arctic Research Center) Summer School (I also taught at the school in 2013). A diverse group of very bright graduate students and early career scientist have come up to IARC at UAF to learn about Earth System Modeling with an emphasis on the Arctic. Student backgrounds range from permafrost to sea ice to biogeochemical cycling and beyond.

Pontificating about modeling: going old-school and using a (white) board

On the first evening Vladimir, who has been running the Summer Schools for well over a decade, organized a BBQ.

Vladimir and food for 30 (notice we are in the healthy zone of the supermarket!)


Fellow Instructor Gijs de Boer is the burger patty master

One afternoon we took a walk to a local research site to investigate some permafrost. For many students this was a new experience and provided a nice taste of the Arctic (complete with mosquitoes!)

Vladimir, Santosh, Marc and Charles measuring the active layer thickness in local Fairbanks permafrost
Hrishi (with the Infrared thermometer), Hyunsuk, Danica, Nicole (holding the moss plug) and Daniel in the forest site taking note of the temperature gradient in the moss. It was 26C at the top and only 5C at the bottom (after being exposed to warm air)
Nicole and Marc taking measurements of subsurface ground temperature

The temperature down near the permafrost was, as expected, near the freezing point. The infrared thermometer was registering temperatures of 0.0C to 0.2C

Hrishi, Niki, Lei and Danica getting first hand experience with organic soil and mosses

Observation can involve all the senses - Julia is giving moist moss the sniff test

The 2016 IARC Summer School Crew



Saturday, October 3, 2015

How cold is cold?


The coldest temperature recorded on Earth using a thermometer, was -89.2C (-128.6F) at Vostok Station, in Antarctica, back in 1983. However,  my colleagues at the National Snow and Ice Data Center believe they found a temperature of -93.2C (-135.8F) near Dome Fuji (Antarctica) using the Landsat 8 satellite. There is a hope to establish an Automatic Weather Station (AWS) at this location to record the temperature at 2m above the ground.

The warmest temperature ever recorded at South Pole was -12C (9F) - it is always cold at the South Pole! South Pole station sits at an elevation of 2,835m (9,300ft) which adds to the cold and the annual average temperature there is about -49C (-56F).

Lars and Doug installing equipment on a cold and windy day. Ten minutes later Lars came back into the hut saying that his eyelids had almost frozen shut.

Outside our instrument hut, Zodiac Camp, the still air temperature fell below -40 C/F (which is the same temperature in both Celsius and Fahrenheit) this WINFLY season. However, if you add a small bit of wind in such conditions, the "Wind Chill" temperature makes the cold feel all the more serious.


The NOAA Windchill chart, with temperatures in Fahrenheit. Some basic conversions to Celsius: 0C=32F, -18C=0F, -40C=-40F.


A cold day at Zodiac Camp. At the start of the day exposed skin would be subject to frostbite within 10 minutes.


Perhaps the coldest day of 2odiac Season 1 (summer) at the Lorne station up on the Ross Ice Shelf with Mike, Anita and Lars (November, 2014). We moved the Ozone sensing station back to the surface as it had been buried with accumulated snow. The station was heavy and the snow was hard; it was a solid day of work.

For the Australian's reading this, the coldest temperature recorded in Australia was -23C (-9.4F), at Charlotte's Pass in the Snowy Mountains on June 29th, 1994.

The coldest temperature recorded in the United States was -52C (-62F), at Prospect Creek in Alaska, January 23rd, 1971. For Boulder, Colorado, the temperature once dropped to -36C (-33F) on January 17, 1930.

Monday, September 28, 2015

Anemometers and wind

Antarctica is a notoriously windy place.  The windiest place on Earth is said to be Commonwealth Bay, Antarctica, where winds often exceed 240km/h (150mph) and the average wind speed is 80km/h (50mph). The cold dense air that forms high on the Antarctic plateau can rush down to the coast at tremendous speeds under the force of gravity; these are known as Katabatic Winds. On the night of 17th Sept. the peak gust at McMurdo was 67.5 knots (125km/h, 78mph).

Wind carries particles (aerosols) and blows snow around so it is an important quantity for us to measure. We are using two instrument for measurement; a traditional cup anemometer on our weather station and a sophisticated sonic anemometer. The "sonic" measures the travel time of pulsed sound waves, which will speed up if assisted by wind - it can measure wind speed and direction up to 20 time a second (20 Hz).

Our weather station, with cup anemometer, at Zodiac Camp. A faint solar halo can be seen around the sun; this is caused by light refracting off ice crystals high in the atmosphere.



Aligning cable to the sonic anemometer has to be done very carefully; we have to lay cables out quickly while still they are still warm as the very cold temperatures makes some cables brittle and they will shatter if moved too much afterwards.


Doug drilling anchor holes while Lars and Mike "supervise" and fine tune their shovel leaning technique. It was a very pleasant -20C/-2F during this installation so none of us are wearing our big jackets.

To anchor the mast of the sonic anemometer we drill a V-thread into the sea ice and loop the guy lines through it. The ice anchor is very strong and can easily take the body weight of a couple of people. (Photo: D. Goetz)

The head of the sonic anemometer senses wind speed in 3-dimensions (north-south, east-west, up-down)

Once installed and guyed, we mark the lines so we don't trip on them in low visibility. (Photo: D. Goetz)
The wind rose from Zodiac Camp for 17 days of the campaign. The dominant southerly winds of Antarctica are wrapped around Mt Erebus on Ross Island to hit our camp from the east and south-east. We have chosen the camp location carefully so that we are sampling clean air and are not downwind of McMurdo Station. The maximum wind speed at Zodiac Camp was 31.3 m/s (70mph, 61kts, 113km/h).


Saturday, September 26, 2015

Science Neighbors

There are only four (4) science groups at McMurdo during WINFLY. It is a very friendly atmosphere among the science teams as everyone understands the difficulty of working in Antarctica. Radio chatter will often be about conditions near various science camps or observations that could be relevant to each others projects... and the opportunity to poke fun at another team is rarely missed.

Last Sunday we car-pooled (matt-track-pooled?) with members of team B-017 who work on understanding how seals navigate (see previous blog entry about B-017). They invited us for "chips and dip" at their camps... though this isn't what you may be thinking - it refers to using an ice chipping bar and a dip net.

Lars dip netting ice out of a seal breathing hole in order to keep it open and unfrozen. The plastic tube directs warmer air blown from the top of the tent down towards the hole in an effort to minimize refreezing.

Chipper bars (left) that are used to maintain a breathing hole. The "cookie" is designed to plug up a hole. Lars (black) and Traci (red) had been shoveling ice out of this hole.

Traci and Jason put the cookie in the hole.

A happy Weddell Seal.

Another group working in our vicinity is B-134, who study Antarctic Invertebrates. We rendezvoused with them out near the edge of the sea ice one evening as we were searching for frost flowers. 

Kevin (L) and Gretchen (R) of B-134 carry their samples back to their PistenBully. It's not a particularly good photo because all cameras were freezing up in the cold temperatures and there was not enough time to adjust exposure before the camera died. Frozen cameras are just one challenge of working in Antarctica.

Team B-259, aka SIMPLE, work close to the McMurdo Ice Shelf which is quite a way from the other teams. They are putting a robotic sensor under the ice shelf to investigate the sub-ice ecosystem. I don't have any photos of SIMPLE in the field, but their team played a great set at the Carpenter Shop Party on Saturday, which signifies the end of WINFLY and start of Main Body at McMurdo.

Peter and Chris lead the vocals

Team SIMPLE rock out


Thursday, September 24, 2015

Snow

Antarctica is the coldest, highest and driest continent in the world. It is largely a desert, with most places receiving less than 250mm of water equivalent each year. Despite low precipitation, snow is often mobile at this time of year (September) due to unsettled weather, very cold temperatures and some very high wind speed events. The interplay of wind speed and snow surface conditions create many patterns in the snow as the battle between snow deposition and erosion takes place.

Surface forms in snow can be similar to those in sand, but an important difference is that snow crystals will sinter and bond with each other, meaning that some erosion derived forms, such as sastrugi, are only found in snow. The rate of bonding is a function of temperature, so in the cold of Antarctica snow can remains mobile longer than more temperate snow climates.


Anondo collecting samples among the drifting snow.

Patterns of wind affected snow. The whole photo is about 30cm (1ft) across.

Striated, wind eroded snow (left side) along with some pit marks on the upper surface 

The sound of snow in Antarctica. The main point of interest in this video is the sound of my boots walking across the very cold, dry and well packed snow - the snow crystals are crushing or grinding against each other. It sounds (and feels) a bit like styrofoam.

Footsteps in time? Pressure caused by footsteps (in the foreground) sintered previously deposited snow, making it harder and more resistant to erosion during the next wind event
Small sastrugi, created by erosion, can be seen in the foreground. Mt Erebus is in the background.

Barchan/Dune like formations. The Gerber multi-tool is about 11cm (4.25") tall. The wind has blown from left to right, with the darker eroded tail on the left side and the brighter deposition zone on the right side

Snow ripple formation, similar to that seen in a stream bed

This post is inspired by recent work from colleagues in Alaska (Filhol & Sturm, 2015).

Tuesday, September 22, 2015

Fata Morgana

Polar regions can produce some interesting optical effects due to extreme temperatures and/or low sun angles. Yesterday was beautifully calm at Zodiac Camp and an inversion formed (i.e. when air closer to the surface is colder than the air above it - normally air temperatures decrease with altitude). The colder, denser air near the surface has a higher refractive index compared to the warmer (though still cold) and less dense air above it. The difference in refractive index acts like a lens, bending light.

Yesterday's inversion produced a Fata Morgana; a phenomenon where, to the observer, an image of the underlying surface is mirrored in the air above it. Often it looks like the horizon line is stretched.

The Fata Morgana can be seen as a white bar (probably as a result of the underling snow  and sea ice) on the horizon. The blue line give a partial outline of the faintly visible Royal Society Range of mountain.

Friday, September 18, 2015

Instrument Surgury

The scientific results from field campaigns are well reported in academic journals, often with text such as "measurements were taken during ...". However, the effort required to produce these results, including all the problems that had to be overcome, are rarely documented in full.
 
2odiac 2015 has not been a simple case of transporting instruments to Antarctica and deploying them. One instrument (the UHSAS) was completely destroyed during shipping; very disappointing, particularly for team member Anondo.

Our primary instrument, the Aerosol Mass Spectrometer (AMS), then suffered a power unit failure, but the ingenuity of McMurdo came to the the fore. Inquiries across the base resulted in the offer of two old power transformers. Using some master engineering skills, Team 2odiac rigged a solution and measurements could continue.

Mike, Doug and Lars assess the power module situation and contemplate a solution. Lars is wearing an anti-static bracelet.

With measurements running, it is important to monitor incoming results to ensure that good data is being collected.

Mike checking the status of the AMS
Some anomalies in results suggested that there might be a problem with one of the pumps on the AMS, so further investigation is required.

All hands on deck. Doug (hiding behind the AMS), Mike and Lars dealing with removing the troublesome vacuum pump

The pump was removed and the pump-to-AMS seal serviced.

The troublesome pump gets a servicing. Mike is wearing a hat and gloves to ensure minimal contamination. This is a delicate instrument - the fan/turbo in this pump spins at an incredible 70,000 revolutions per minute.


Lars and Mike reinstall the pump.

Doug bends over backwards during pump installation

More hands in the delicate environment of the AMS. The NOx, CO2, Ozone analyzer and the computer server are on the right edge of the picture.

Even when things stray from the original plan it's good to have a sense of humor. Mike and Doug share a joke as everyone discusses the situation. I have enjoyed working with Anondo, Doug, Lars and Mike.


Wednesday, September 16, 2015

Flagging

The weather in Antarctica is notoriously fickle. It can be sunny with glorious views of glaciers, ice sheets and mountains, but within an hour a raging storm may engulf you in a white-out. A white-out is just that - blowing snow and winds mean that all you see is a white void and having any sense of direction can be extremely difficult.

Many research sites (including ours) are located on the barren white landscape of the sea ice - yes, we are driving over the ocean! A white-out poses a serious travel risk so all main routes to research sites on the sea ice are set with flags spaced at 25m (~80ft). This is a time consuming, but very important, process.


A blowing snow event and a row of flags marking the road to research sites


 
A ground blizzard en route to Zodiac Camp. The flag in the top left corner is only 25m away, but can barely be seen.


To set a flag line, we use a Kovacs Ice Auger and drill holes using either a battery powered drill, or a gas/petrol powered drill (called the Echo drill) or some good old muscle with a brace-and-bit.




Going old-school (after the batteries died on the DeWalt and the Echo drill wouldn't start). Doug and Lars put in some muscle to drill a hole with the brace

Lars runs the Echo drill, while Doug readies the flags.

The Turkey-tail of flags marking the turn off to Zodiac Camp. Lars drilled all the way through the sea ice at this location. The ice was 2m (6.5ft) thick.