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Modelling tracer transport by a cumulus ensemble: Lateral boundary conditions and large scale ascent. Advective timescale: necessary condition for model results to be meaningful:. CRM. Specified lateral boundary conditions (SLBC, horizontal advection) - PowerPoint PPT Presentation
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Modelling tracer transport by a cumulus ensemble:
Lateral boundary conditions and
large scale ascent
Specified lateral boundary conditions (SLBC, horizontal advection)
Advection of tracers by the large scale vertical wind (VLSAT)
Previously (Lu et al., 2000): periodic boundary conditions in cumulus ensemble model also for tracers, but
no prescribed horizontal LSA for tracers
Advective timescale:
necessary condition for model results to be meaningful:
U
Lsim
CRM
)()(
zU
Lz
Specified lateral boundary conditions (SLBC, horizontal advection)
Advection of tracers by the large scale vertical wind (VLSAT)
Previously: the effect of net large scale ascent e.g. over the
Pacific Warm Pool is considered for q,
BUT IT WAS NEGLECTED FOR TRACERS
case study of the influence of deep convection on atmospheric chemistry
motivation
developed by NCAR and others
2D or 3D
fit for small scale meteorological phenomena
www.wrf-model.org
WRF – Weather Research and Forecast Model
TOGA-COARE intensive flux array
SATELLITE PIC
ISCCP clouds
IR retrieved cloud top temperaturese.g. Rossow and Schiffer, 1999
MCS schematic
1000hPa wind
Kalnay et al., 1996
westerly wind burst
Ciesielski et al., 2003
ozone
flight dates: 94/02/07-94/03/14 Emmons et al., 2000 Thompson et al., 2003
SHADOZ, WOUDC
Lawrence et al., 2003
z
qwqk
t
q
zw
t
LS
LS
v
v
adj
obs
LSt vvv
large scale advection
new:
zw
t obsLS
and SLBC
2D runs, 500km horizontal domain
350m vertical grid spacing in the troposphere
Walcek (2000) advection scheme
3(2) different setups:
periodic lateral boundary conditions (PLBC, k=1)
specified lateral boundary conditions (SLBC, k=0)
u, (v), w, q, C=
SLBC+VLSAT (k=0)
Sensitivity Runs – Idealized Tracers
Hovmöller Diagrams
rain, T, q
Tracer transport
idealized tracers
horizontally homogeneous intialization
3 different tracers:
BL tracer (0-1750m)
MT tracer (7000-8750m)
UT tracer (12250-14000m)
Tracer transport
Tracer transport
Tracer transport
Tracer transport
Tracer transport
time integrated, horizontally avearged tendendencies
conclusions/perspectives
presented a study of idealized tracer transport
SLBC necessary for
TLSAT important (not included in previous study)
chemistry version based on MATCH
data from measurements necessary for SLBC
use WRF nesting capability
comparison with SCM
U
Lsim