HIAPER Progressive Science Mission - START05
Atmospheric flow analyses
Prof. Kenneth P. Bowman
Department of Atmospheric Sciences
Texas A&M University
This material is based upon work supported by the National Science Foundation under Grant No. 0605739.
Maps and cross-sections of flow deformation
North America
Additional cross sections
Northern Hemisphere
Description of Maps
The maps show the deformation (strain) of the atmospheric flow field computed using a Lagrangian method. Sheets of particles are initialized on isentropic surfaces and integrated forward and backward in time. The quantity plotted in shades of red and blue is the horizontal separation of adjacent particles (strain) at the time indicated in the map title. The aim is to identify hyperbolic regions (saddle points) in a complex, time-dependent flow. Hyperbolic regions are responsible for rapid stirring (folding and stretching).
Backward trajectories are computed using (primarily) analyses. Forward trajectories are computed using forecasts. All velocities are from the NCEP Global Forecast System (GFS). For this calculation we use GFS data at 6-hour intervals on a 1 degree x 1 degree global grid in pressure coordinates. Trajectories are fully three-dimensional, using the model's large scale vertical velocity (omega).
In the maps, red indicates boundaries between air coming together from widely-separated locations (unstable manifolds), while blue indicates air diverging toward widely-separated locations (stable manifolds). The intersecting stable and unstable manifolds define lobes, which are regions of fluid being stretched and folded by the flow.
The various map panels include overlays of Montgomery streamfunction and potential vorticity.