Steve Koch on November
13, 1997 at 17:50:26:
(this may be considered to be a modification of Ziegler Hypothesis
(4)): Whether or not an important thermally-forced circulation develops
transverse to a frontal boundary depends upon the subtle interaction
between the effects of the total cloud cover distribution and the
moisture availability field, the latter being determined by a nonlinear
relationship between fractional vegetation cover, surface soil moisture,
and root zone soil moisture. Thermal solenoids of significance for
initiation of convection will only form in situations wherein the
differential cloud cover acts synergistically with the moisture
availability field to produce a net horizontal gradient of surface
sensible heat flux in such a manner that the flux is greatest on
the warm side of the front. This is consistent with the predictions
of the Sawyer-Eliassen equation for the frontal circulation produced
by diabatic forcing.
Koch, S. E., and A. C. Ray, 1997: Mesoanalysis of summertime convergence
zones in central and eastern North Carolina. Wea. and Forecasting,
Koch, S. E., A. Aksakal, and J. T. McQueen, 1997: The influence
of mesoscale humidity and evapotranspiration fields on a model forecast
of a cold frontal squall line. Mon. Wea. Rev, 125, 384-409.
Koch, S. E., J. McQueen, and V. M. Karyampudi, 1995: A numerical
study of the effects of differential cloud cover on cold frontal
structure and dynamics. J. Atmos. Sci. 52, 937-964.
Dorian, P. B., S. E. Koch, and W. C. Skillman, 1988: The relationship
between satellite-inferred frontogenesis and squall line formation.
Weather and Forecasting, 3, 319-342.
Koch, S. E., 1984: The role of an apparent mesoscale frontogenetical
circulation in squall line initiation. Mon. Wea. Rev., 112, 2090-2111.
||The same instrumentation proposed by Ziegler and Mitchell,
namely aircraft stepped traverses, mobile soundings, surface heat
fluxes from the OK Mesonet and mesoscale models, soil moisture from
those Mesonet sites that will be measuring it (but spatially enhanced
with coop raingauge data), and though not mentioned by them, we also
need to determine whether such a solenoidal circulation is even present.
I propose to do that with the same methodology that I proposed for
my Narrow Cold Frontal Rainband hypothesis, namely reliance upon the
WSR-88D, Profiler Network, and one or more 915 Mhz profilers, in conjunction
with aircraft traverses. Vegetation will be obtained from NDVI fields
from NOAA-9 satellite.