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About the CASLab

The physical environment at the CASLab

Where is the CASLab?

The CASLab is located close to the Weddell Sea coast. As the coast effectively forms a promontory at this point, the CASLab is exposed to the Weddell Sea in three directions. The surrounding area is flat and snow-covered with the nearest rock outcrops roughly 200 km away.

Sea ice/open water influence

During the summer months, an open water lead, that can be several tens of kilometers wide, extends along the ice front. During the winter, open water leads form regularly when the prevailing easterly winds force sea ice offshore. In particular, Precious Bay, to the south west of Halley, is normally ice free during winter and spring such that air arriving at Halley from this direction (the secondary wind-rose maximum) is likely to have had contact with open water.

Wind rose showing wind speed and duration for 2007 at the CASLab
Annual light regime

At Halley, the sun stays permanently above the horizon from November 2nd to February 9th, and permanently below the horizon from April 30th to August 13th. Prior to sun-up and after sun-down, scattered light can be observed at Halley for several hours around solar noon.

Annual wind speed and temperatures

Wind speeds at Halley vary considerably through the year from very calm conditions to storms (mainly in winter/spring) gusting to 25 ms-1. Annual temperatures at the Halley CASLab range from just below 0°C in summer to around −45°C in winter.

Windspeeds and temperatures at the Clean Air Sector Laboratory (CASLab) (grey shading = polar night; yellow shading = polar day)

CASLab site information/access

Approach to the Clean Air Sector Laboratory (CASLab)
Approach to the Clean Air Sector Laboratory (CASLab)

The CASLab was commissioned in 2003 at BAS’s Halley V station (75°35′S, 26°34′W). It operated successfully for five years before a temporary suspension during the construction of the new Halley VI station. In January 2012, the CASLab was installed at its new location at Halley VI (75°35′S, 26°10′W). The new site is some 20 km from Halley V, and has effectively identical environmental conditions.

The CASLab sits approximately 30 m above sea level on the floating Brunt Ice shelf in the Atlantic sector of coastal Antarctica.

Satellite image of Halley VI showing the CASLab location within the red circle. Image: BAS/Digital Globe
Satellite image of Halley VI showing the CASLab location within the red circle. Image: BAS/Digital Globe
The CASLab is situated 1 km from the station generators, in a clean air sector that receives minimal contamination from the base.

Access to the laboratory is on foot or by ski — vehicle access is limited to a few occasions each year for delivery of equipment.