Modelling tracer transport by a cumulus ensemble: Lateral boundary conditions and

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