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Upper-Level Atmospheric Divergence
Background:
Using the gridded atmospheric
motion vector output u and v AMV components are
averaged over the 150, 200, 250, and 300 hPa levels.
Divergence 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 divergence values are shown with solid lines,
negative values (convergence) are shown with dashed lines. Units are 10-6s-1.
Uses:
Upper-level atmospheric divergence can be used by tropical
cyclone (TC) forecasters to estimate the strength of the TC
secondary circulation, including the low-level inflow into the
TC core, the convective updraft strength within the TC eyewall,
and the resulting outflow/venting at the top of the TC. This
dynamic can be important for storm growth and development. An
area strong upper-level divergence 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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