Environmental Engineering Reference
In-Depth Information
1. Introduction
The primary objective of this project was to demonstrate a methodology that is
able to give estimates of ozone concentrations under climate change conditions for
any period or location in Australia, and to specifically give an insight into the impact
of climate change on ozone levels in Sydney in 20 and 50 years time. Ten year
periods were chosen for detailed high-resolution chemical transport simulations
(1996-2005 [decade 1], 2021-2030 [decade 2] and 2051-2060 [decade 3]) in order
to enable the inter-annual variability in ozone climate to be addressed. A second
objective was to estimate the decrease of emissions which may be needed to
maintain ozone levels below National Environment Protection Measures (NEPM)
standards where 1-h peak ozone concentration is 100 ppb and 4-h peak of 80 ppb
with an allowable exceedence of 1 day/year.
2. Description of the Modelling System
The downscaling system set up for this project consists of nesting an urban/
regional atmospheric transport and chemistry model (TAPM-CTM) with 3-km
inner grid spacing, into the regional meteorological fields (60-km grid spacing)
generated by the stretched grid atmospheric model (CCAM) which in turn is
nudged towards global-scale meteorological fields generated by the CSIRO-Mk3
Global Climate System Model. CSIRO-Mk3 and CCAM were forced by one of a
family of A2 Special Report on Emissions Scenarios (SRES). CCAM is formu-
lated on a conformal-cubic grid which covers the globe, but can be stretched to
provide higher resolution in an area of interest. Because of its higher resolution,
CCAM is, in principle, able to generate more accurate climate predictions over
Australia, with particular emphasis on the Sydney region. CCAM was integrated
for the period 1961-2100 for the purposes of the current study and meteorological
boundary conditions suitable for use with TAPM-CTM were generated for the
period 1996-2005, 2021-2030 and 2051-2060.
Emission inventories for on-road mobile source, industrial, commercial and
domestic emissions for the Sydney Greater Metropolitan Region (GMR) were
provided by NSW Department of Environment and Climate Change. Emissions
from natural sources (NO
x
from bacterial activity in soils; VOC emissions from
plants) were modelled internally in CTM.
3. System Performance for the Decade of 1996-2005
An important component of this project is an assessment of the capability of the
dynamic downscaling system to reproduce the observed fields of the relevant
