Greenland acts as a barrier in the atmosphere so forces a number of orographic winds, such as barrier flows at its flanks and katabatic flows over the steepest parts of the ice sheet. Barrier flows run parallel to the mountains, below mountain height and approximately in geostrophic balance. Katabatic flows run approximately down slope, are shallow and are forced by density gradients from net cooling at the surface.
These orographic flows dramatically affect the large-scale atmospheric circulation and the air-sea-ice interactions in the adjacent Greenland, Iceland and Irminger Seas. Furthermore, both the sea-ice around Greenland and the ice sheet itself are changing dramatically in response to anthropogenic climate change and this is changing the role of these orographic flows in the climate system. The Greenland and Iceland Seas are currently a major focus of attention as they host key processes that generate the headwaters of the Atlantic Meridional Overturning Circulation. It has recently been demonstrated that variability to the East of Greenland dominates the variability of the AMOC; and that the retreating sea-ice here is impacting the generation of dense water in this region. Research plans
In this project, you will examine barrier winds and katabatic flows over Northeast Greenland – a region where they have never been studied. You will examine several case studies using simulations from a state-of-the-art numerical model and observations. You will place these into a climatological context using the latest meteorological reanalyses products. And you will carry out an analysis of coupled climate model output to determine the climatological impact of these flows on the ocean under different sea-ice conditions. You will build on research focused on barrier winds and katabatic flows off SE Greenland, where aircraft-observations were made in 2007 and the late 1990s. But focus on NE Greenland, which has been far less studied, but is now the location of reduced sea-ice extents in both summer and winter. You will investigate the changing role of these orographic flows on the ocean and the climate system. Training and skills
You will be trained to run and analyse numerical simulations of the atmosphere; and analyse output from both the atmospheric and oceanic components of a climate model. The numerical models will be the MetUM (the Met Office Unified Model of the atmosphere) and HadGEM3 (a configuration of the Met Office’s climate model). The MetUM is the Met Office’s state-of-the-art numerical weather prediction model, used for operational weather forecasting, research and as part of all of their climate models. The supervisory team have extensive experience of using and developing the MetUM. You will need to become an expert in data analysis using Python and/or Matlab. Aircraft observations from the recent Iceland Greenland Seas Project – and the Greenland Flow Distortion Experiment in 2007 – will be available and new aircraft observations from a funded Summertime Arctic Cyclones field campaign in August 2021 should also be relevant. The lead supervisor is co-leading this campaign and will suggest flying some orographic flow missions as secondary objectives. In addition, routine observations from the few meteorological stations on the coast of Greenland will be available.