MC
5417
Candidate
Kwan Tsaan Lai | Applied Math, University of Waterloo
Title
Sensitivity of Idealized Squall Line Simulation to Resolution and Subgrid Turbulence Mixing
Abstract
In
this
project,
the
sensitivity
of
idealized
squall
line
simulation
to
horizontal
grid
spacing
and
turbulent
mixing
parameterization
will
be
discussed.
Inconsistent
results
from
numerical
simulations
of
convective
system
have
suggested
that
there
are
issues
with
the
behavior
of
the
subgrid
turbulent
mixing
parameterizations
with
increasing
resolution
that
still
need
to
be
resolved.
The
Weather
Research
and
Forecasting
Model
(WRF)
will
be
used
to
perform
large
eddy
simulations
of
idealized
squall
lines
with
horizontal
grid
spacing
of
4
km,
1
km,
500
m
and
250
m.
A
common
background
sounding
profile
is
used
so
that
simulations
from
this
project
can
also
be
compared
with
other
studies
in
the
literature.
The
dependence
of
various
squall
line
characteristics
on
resolution,
including
cloud
top
height
and
mass
flux,
turbulence
kinetic
energy,
energy
spectra
and
backscatter
will
be
discussed.
In
particular,
we
find
that
4
km
grid
spacing
is
not
recommended
for
simulations
with
explicit
convection
as
it
contains
an
unreasonable
amount
of
subgrid
turbulence
kinetic
energy
and
it
is
not
able
to
resolve
the
large
energy
containing
eddies.
A
significant
amount
of
backscatter
exists
in
simulations
with
$\Delta
x=$
4
km
and
even
1
km,
which
is
ignored
by
the
eddy
viscosity
model.