Dw. Waugh et Ra. Plumb, CONTOUR ADVECTION WITH SURGERY - A TECHNIQUE FOR INVESTIGATING FINESCALE STRUCTURE IN TRACER TRANSPORT, Journal of the atmospheric sciences, 51(4), 1994, pp. 530-540
We present a trajectory technique, contour advection with surgery (CAS
), for tracing the evolution of material contours in a specified (incl
uding observed) evolving flow. CAS uses the algorithms developed by Dr
itschel for contour dynamics/surgery to trace the evolution of specifi
ed contours. The contours are represented by a series of particles, wh
ich are advected by a specified, gridded, wind distribution. The resol
ution of the contours is preserved by continually adjusting the number
of particles, and finescale features are produced that are not presen
t in the input data (and cannot easily be generated using standard tra
jectory techniques). The reliability, and dependence on the spatial an
d temporal resolution cf the wind field, of the CAS procedure is exami
ned by comparisons with high-resolution numerical data (from contour d
ynamics calculations and from a general circulation model), and with r
outine stratospheric analyses. These comparisons show that the large-s
cale motions dominate the deformation field and that CAS can accuratel
y reproduce small scales from low-resolution wind fields. The CAS tech
nique therefore enables examination of atmospheric tracer transport at
previously unattainable resolution.