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Lower-Level Atmospheric Convergence
Background:
Using the gridded atmospheric
motion vector output u and v AMV components are averaged over
the 850 and 925 hPa levels. Convergence is computed using
finite differencing of -(du/dx + dv/dy), where u and v are the
wind components and x and y are the horizontal grid spacing.
In the plots positive convergence values are shown with solid
lines, negative values (divergence) are shown with dashed lines. Units are 10-6s-1.
Uses:
Lower-level atmospheric convergence analysis can be used by
tropical cyclone (TC) forecasters to identify potential areas
where TC development may occur. Since the development of the TC
secondary circulation (low-level inflow, updrafts in the
TC eyewall, and upper-level outflow) is essential in the
maturation and sustainment of a TC, identification of regions
where strong TC convergent inflow near the surface can pinpoint
those regions which are in favorable environments. An area of
convergence can be seen in the blue box of
this figure.
For more AMV information, please visit the
International Winds Working Group (IWWG)
page.
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