MALTA CLIM
MATE TEAM
Department of Physic
p
y cs, Faculty of Science
,
y
E: climate‐physics.sci@um..edu.mt T: +356 2340 3036
Evaluating the Land Surface Model of the RCM PRECIS
A regional analysis of Australian climate in relation to ENSO using the RCM PRECIS
Mr. William Healey
E: whea0001@um edu mt
E: whea0001@um.edu.mt
Ms. Candy Spiteri
E: cspi0015@um edu mt
E: cspi0015@um.edu.mt
Land Surface Models
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ENSO phenomenon
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The Climate is studied using computer models which take into account energy from the sun, atmospheric compositions,
ocean‐atmosphere
t
h
system.
t
the oceans and the surface of the Earth.
•
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The interaction of the surface with the atmosphere consists of energy and moisture fluxes due to vegetation, barren lands,
This phenomenon happens at irregular intervals of 2‐7 years and
lasts nine months to two years.
urban cities and stretches of water.
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El Niño Southern Oscillation (ENSO) is a free oscillation of the
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These calculations are assigned to the Land Surface Model within the Climate model.
The strength of the Southern Oscillation is measured by the
Southern Oscillation Index (SOI).
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Negative SOI values, in the time series represents El Niño events
and positive SOI values represents La Niña events.
Australian climate in relation to ENSO
Energy budget on the Earth’s surface in terms of radiation absorbed and reflected
The exchange of water between surface and atmosphere
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Climate models can cover a large global domain however at a low resolution
Climate models can cover a large global domain however, at a low resolution.
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Regional Climate Models (RCMs) use Lateral Boundary Conditions (LBCs) to account for inputs from the outside of the domain.
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Calculations of processes from the Land Surface are taken into account within each grid box.
Some Results
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Flooding in Victoria resulting from the Flooding
in Victoria res lting from the
current La Niña event, January 2011.
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El Niño conditions result in warmer than average Pacific ocean and westerly trade wind temperatures.
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p
from west to east,, takingg rain with it,, causingg extensive drought
g in Australia.
Duringg an El Niño event,, warm Pacific water spreads
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The El Niño effects on Australia are mainly: a rise in surface pressure, westerly winds, above average surface temperatures and below
average rainfall.
PRECIS (Providing REgional Climates for Impact Studies) was the RCM
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used for the study over Australia at a resolution of 50 km  50 km.
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Drought scene in New South Wales Dro
ght scene in Ne So th Wales
during El Niño event 1982.
La Niña event result in cooler than average Pacific ocean and climatic conditions are reversed.
reversed
The simulations were run with two versions of the LSM,
LSM MOSES 1 (Met
Office Surface Exchange Scheme) and the updated version MOSES 2.2.
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Two LBCs were applied, ECHAM5 and HADCM3Q0.
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M d ll d results
Modelled
lt were compared
d to
t measured
d data
d t for
f a time
ti
period
i d
from 1960‐2020.
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MOSES 1 – ECHAM5
MOSES 2.2 – ECHAM 5
R lt
Results and Analysis
dA l i
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C l di R
Concluding Remarks
k
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M
Measured spatial plot d
ti l l t
Temperature and moisture parameters where studied at different
levels.
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PRECIS
PRECIS spatial plot ti l l t
Variation of data in MOSES 2.2 is closer to the variation in measured
data than that of MOSES 1.
1
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MOSES 1 – HADCM3Q0
MOSES 1 –
The spatial image on the right shows the 30 year average for surface
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This suggests an over prediction in tropical regions and an under
prediction in temperate regions.
These results suggest an under prediction from
PRECIS.
temperature
temperature.
MOSES 2 2 – HADCM3Q0
MOSES 2.2 –
The time series shows measured and modelled rainfall
in mm/day as extracted from Weipa Aero station (4).
produced for the 12 stations chosen (shown on the left).
HadCM3Q0 results are less biased than results from ECHAM5.
Greater differences detected in Tropical regions.
Monthly
o
y aand
d aannual
ua timee se
series
es co
covering
e g 1960‐1990
960 990 aand
d 1990‐2020,
990 0 0, were
ee
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ENSO events were visible in these results.