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Atmospheric Gadgets

SODAR and RASS equipmentAtmospheric research equipmentKiteThe most obvious thing when we arrived at Camp Curry (sub camp 2), apart from the delicious smell of curry, was the array of interesting and alien looking gadgets along the lakeshore. A day spent with Peyman Zawar-Reza and Marwan Katurji, both lecturers at the Centre for Atmospheric Research at the University of Canterbury, and I’ve now got a handle of what they all do.

But firstly….. the Dry Valleys are dry! Antarctica is the driest continent on earth, which ironically is 98% covered in ice. The Dry Valleys receive around 50mm of precipitation per year at the valley mouths and almost nothing at the head of the valleys. Why? Because of the rain shadow effect from the Transantarctic mountains. Very simplistically the weather in the Dry Valleys is as follows: In the summer under 24hour sun, when there is regionally calm weather, the winds are driven by thermal circulations which causes up valley winds during the day. During the few hours when the low sun casts shadow into the valleys, the temperature drops a few degrees and there is a weak down valley wind. The major weather comes from the outside, in summer low-pressure systems bring strong winds into the valley, and if dense with moisture, snow will fall. In the winter when the circumpolar vortex strengthens, low-pressure systems cause hurricane strength warm foehn winds to funnel down into the valleys. These are the strong winds that pick up sand and blast and erode the rocks causing sculpted ventifacts. 

To understand the biocomplexity of the Dry Valleys ecosystems, it is critical to understand the microclimate. Temperature and water are critical for life. I know that I require water and warmth to live in the Dry Valleys, and a few cinnamon scones! So what causes surface temperature to rise above freezing? And what causes precipitation? 

Marwan and Peyman are also looking at finer scale climate questions. They are interested in the atmosphere very close to the surface - below 500m. Specifically wind interaction with topography, turbulence, waves, and the forcings behind them. The Dry Valleys represent a simplified system with no vegetation, which is ideal for theory and hypothesis testing.

They have some serious gadgets, 700 kilos of gadgets in fact. There is the SODAR (sound detection and ranging), and a RASS (radio acoustic sounding system), a surface automatic weather station, and a kite. The SODAR and RASS instruments measure wind speed, wind direction and temperature in a vertical profile from the ground up to 500m every 10 minutes.

But the most fun, was flying the kite. A beautiful bright yellow and red 4m kite is attached to a hand winch and flown with instruments attached to validating the temperature profiles taken by the RASS up to 300m. It is labour intensive but necessary for checking the remote sensing gear. Kites work better than weather balloons in windy environments, such as the Dry Valleys. 

All in all, after a hospitable night at sub camp 2, a jolly good day eating curry, flying kites and playing with gadgets! Back to Main Camp tomorrow.

Nita Smith.

Peyman and Marwan and the SODAR and RASS equipment
Centre: Peyman and Marwan working on their Atmospheric research equipment
Bottom: Flying the kite with temperature sensor attached to validate the SODAR RASS measurements

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