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The history and key results of the Indian Ocean Climate Initiative (IOCI)

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Title: The history and key results of the Indian Ocean Climate Initiative (IOCI)


1
The history and key results of the Indian Ocean
Climate Initiative (IOCI)
Pandora Hope and IOCI Research PartnersBureau
of Meteorology Research Centre
8ICSHMO, Foz do Iguaçu, Brazil April, 2006
2
Contributions From
IOCI Research Partners Bureau of Meteorology and
CSIRO Jorgen Frederiksen, Lynda Chambers,
Bertrand Timbal, Wasyl Drosdowsky, Scott Power,
Fuqin Li, Zhihong Li, Brian Ryan, Ian Smith,
Wenju Cai, Steve Charles, Bryson Bates Brian
Sadler and IOCI Partners particularly Ian
Foster and Colin Terry Acknowledgements National
Climate CentreA host of others
3
IOCI Partners
Department of Agriculture WA Conservation
and Land Management Environment Planning and
Infrastructure Premier and Cabinet State
Greenhouse Strategy State Water Strategy Fire
and Emergency Services AuthorityForest Products
CommissionWater Corporation of WA Bureau of
Meteorology, WA
4
Outline
IOCI Background Motivation Brief history and
possible future Synoptic Types Method Links with
rainfall Shifts through time IOCI Key messages
5
The most reliable rainfall occurs in the extreme
south-west between Perth and Leeuwin. Here the
rains rarely vary 10 per cent. from their average
amount, and the lot of the farmer should be a
happy one.Griffith Taylor, Australian
Meteorology 1920
http//www.bom.gov.au/cgi-bin/silo/reg/cli_chg/ave
ragemaps.cgi
6
http//www.bom.gov.au/silo/products/cli_chg/index.
shtml
7
Average monthly rainfall SW WA
8
May-July SW WA Rainfall
9
IOCI History and possible future
  • Stage 1 commenced January 1998
  • Understand climate variability
  • Seasonal forecasting targeted forecasts
  • Reports, 1999, 2000, 2001 Final report 2002
  • Stage 2 commenced July 20033 phases, the first
    two have been completed
  • 3 Themes
  • Current Climate Regimes
  • Climate Change
  • Short-term Climate Prediction
  • 2004 Report, Flyers, Workshop
  • Stage 3 Negotiating to commence July 2006
  • www.ioci.org.au

10
May-July MSL Pressure Anomaly(1976-2003 minus
1958-1975)
11
Vertical cross-section of the Southern Hemisphere
July zonal wind (ms-1) averaged over 100E-130E
1949-1968 1975-1994 difference
12
Development of Self-Organising Map
  • Select size and topology of SOM
  • Select size of data region
  • Select neighbourhood function and radius
  • Start with SOM of random numbers
  • Present data to SOM
  • Vector similarity is found via Euclidean distance
  • SOM is trained
  • Data is presented again until error is low

From Kohonen 2001
13
Self Organising Map NCEP/NCAR 1948-2003 June
July 0 12Z MSLP
14
Transitions
Forward transition
15
Self Organising Maps associated rainfall
anomalies
Wet types
Trough to west types
Pandora Hope BMRC
16
Frequency of wet synoptic patterns ( rainfall)
1976-2003 average 27 synoptic trough types, 199
mm rainfall
1958-1975 average 33 synoptic trough types, 241
mm rainfall
Decrease in frequency of wet types accounts
for 50 of rainfall decrease
Decrease in rainfall associated with troughs
to west types accounts for 30
17
Results from 20th Century synoptic study
  • Wet synoptic types have decreased
  • Dry types have increased, to a lesser extent
  • Rain linked with northerly flow types has
    decreased
  • Increase in rainfall linked to southerly flow
    types
  • Average south west rainfall links well with wet
    synoptic types

18
Difference 2046-2065 cf 1961-2000
MRI-CGCM2.3.2
19
SRES B1 2081-2100 Difference
CSIRO-Mk3
GFDL-CM2.0
GISS-ER
MIROC3.2(med)
20
SRES A2 2081-2100 Difference
CSIRO-Mk3
GFDL-CM2.0
GISS-ER
MIROC3.2(med)
21
Synoptic types in future scenarios
  • Increasing levels of greenhouse gases lead to a
    growing reduction in the occurrence of deep
    troughs in the SWWA region in most GCMs.
  • All GCMs examined here show a decline in direct
    model output rainfall with increasing greenhouse
    gas concentrations.
  • These results suggest that, as greenhouse gas
    concentrations rise in the future, it is likely
    that rainfall in SWWA will continue to be low.
    However, decadal variability must also be
    considered.

22
Key Messages from IOCI, Phase 1
  • IOCI (2002) concluded that Most likely, both
    natural variability and the enhanced greenhouse
    effect have contributed to the rainfall decrease
    and that Other local factors, such as land-use
    changes in the southwestseem unlikely to be
    major factors in the rainfall decrease, but may
    be secondary contributors.

23
Key Messages from IOCI, Phase 2
  • The large-scale synoptic changes are consistent
    with the drying in SWWA, providing further
    evidence that the rainfall decline is linked with
    large-scale global circulation changes
  • It is feasible that the drying trend could have
    been the result of unforced climate variability
  • However, at least part of the observed decline in
    rainfall is consistent with the modelled effect
    of anthropogenic forcing
  • Changes in land cover may also have contributed
    to the rainfall decline.
  • The latest set of CSIRO control and transient
    simulations confirm both natural variability and
    greenhouse gas radiative forcing are

24
Key Messages from IOCI, Phase 2
  • The latest set of CSIRO control and transient
    simulations confirm both natural variability and
    greenhouse gas radiative forcings contributed to
    the rainfall decline
  • 20th century simulations generally underestimate
    the observed rainfall decline
  • The latest suite of climate change simulations
    show that even with the most optimistic emission
    scenarios, SWWA is projected to be drier and
    warmer later this century.

25
Thank You
For further details about IOCI and its research,
please speak to Pandora Hope, or visit the
website www.ioci.org.au
Pandora Hope and IOCI Research PartnersBureau of
Meteorology Research Centre
8ICSHMO, Foz do Iguaçu, Brazil April, 2006
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