Dynamics of the boundary layer

(i) Primary objectives

The central objective of this research group is to improve our understanding of the ways in which atmospheric boundary layer processes control the meteorology and climatology of Antarctica. The atmosphere and ice sheets interact through the medium of the boundary layer so fluxes of momentum, heat and water vapour at the ice-atmosphere interface are of great climatological significance. Such fluxes have to be parameterised in GCMs and in glaciological models. We shall continue our programme of surface flux measurements and expand it to cover a range of Antarctic sites. The measurements obtained will be used to develop surface flux climatologies for use in a variety of climatological studies and to aid the development of improved flux parameterisation schemes.

Attention will also be given to studies of mesoscale katabatic flows forced by the interaction of the stable boundary layer with the sloping ice sheet surface. The low-level circulation over Antarctica is dominated by such flows and it is now clear that they exert strong controls on the hemispheric circulation. Investigations will be focused on the Coats Land region, which has relatively simple topography and is close to Halley station where our boundary layer investigations have been centred so far. New techniques will be developed to measure profiles of wind velocity and temperature through the depth of the boundary layer in order that the forces driving these circulations can be quantified.

(ii) Strengths and achievements

Since 1985, the group has developed considerable expertise in making micrometeorological measurements under the harsh conditions experienced in Antarctica. A wide range of boundary layer studies have been carried out at Halley station. These include measurement of surface fluxes and development of flux parameterisations (King, 1990; King and Anderson, 1994), studies of atmospheric internal gravity waves (King et al, 1987; Rees and Mobbs, 1988; Mobbs and Rees, 1989; Rees et al, 1994) and blowing snow investigations (Anderson et al, 1993; Moore et al, 1994). Experience has been gained with a variety of measuring techniques and a useful pool of micrometeorological equipment has been acquired.

The group has developed productive collaborations with a number of University departments. CASE students at the universities of Lancaster, Sheffield, Leeds and Queen Mary and Westfield College have been involved with data analysis and modelling associated with the Antarctic boundary layer studies. Development of such collaborations (which are mostly envisaged to continue into the coming quinquennium) has greatly increased the productivity of the group and has maximised the amount of information which can be extracted from datasets collected in the Antarctic. The group also benefits from good contacts in the Boundary Layer Research group at the UK Meteorological Office.

(iii) Future strategy

Halley Research Station will remain the major centre for fundamental process studies because the Brunt Ice Shelf provides a near ideal location for such work and these studies are most conveniently carried out at a permanent station. However, in order to meet the project objectives, we will need to embark on a new programme of measurements at remote sites.

It is envisaged that the fruitful collaborative links established with various University groups over the past few years will continue to play an important role in this work.