The 2008 IOD Event
A third-in-a-row positive IOD event has evolved in 2008 following two consecutive IOD events of 2006 and 2007. This is a very rare occasion when we have three consecutive positive IOD events back to back. No such previous occurrences are detected in the historical SST records.
A positive IOD brings heavy rain to East Africa and droughts to Indonesia and parts of Australia. Usually, parts of East Asia including Japan suffer from dry hot conditions during a positive IOD event whereas Southeast Asia suffers from floods. Indian summer monsoon rainfall as a whole remains above normal during a positive IOD.
2008 IOD in News:
Rain hopes fading: The Weekly Times
23/04 - Farmers across southeast Australia may have to wait until spring for drought-breaking rain, according to Japanese long-range forecaster Toshio Yamagata.
Kompass – Indonesia
Discussions during 2008 IOD evolution:
17 June 2008, Saji Hameed wrote
Yes, certainly an interesting situation - but maybe a bit too early to foresee the development of a positive IOD, as far as observational evidence is concerned. A week or two more of waiting would clarify if the anomalies will grow further. With such an early start, there is a good chance that the IOD event will be quite a strong one and also may initiate warm SST anomalies in the Nino regions.
APEC Climate Center
16 Jun 2008, Swadhin Behera wrote:
Thanks for the update on the 2008 IOD evolution. The conditions are very much favorable now for another big IOD event.
The Weekly Times has already reported this possibility in April to caution the local farmers and I think they are supplementing it with regularly updates. The first article is attached here for reference. An Indian newspaper, the Hindu, also reported the possible evolution of the positive IOD and its impact on the current monsoon rainfall there.
I understand that several agencies in Southeast Asia are also eagerly watching this evolution to take precautionary measures.
16 Jun 2008, Peter McIntosh wrote:
Dear Cai and colleagues
The chances of a positive IOD have been growing steadily for the last month or so. Over this period, we have been keeping our contacts in SE Australia advised about developments, mainly through the Birchip Cropping Group. This is not ideal, since the information doesn't reach all farmers. After getting many enquiries about the coming season, I have started to gather together useful links in one place. See http://www.marine.csiro.au/~mcintosh/SeasonalClimate.htm . Additions and suggestions are welcome.
The Victorian Dept. of Primary Industries issues a newsletter called "The Break" which is emailed widely to farmers and researchers in SE Australia each month. The May (latest) issue advises of the increasing chances of a positive IOD, based on four computer models (SINTEX, POAMA, ECMWF and CFS). You can find this newsletter at http://www.dpi.vic.gov.au/climaterisk . A very useful table presents SST and rainfall seasonal predictions from multiple sources. Since conditions are changing quite rapidly, an updated newsletter called "The Fast Break" is being prepared containing more observations and model predictions. This should appear shortly at the same web address.
The Australian Bureau of Meteorology has recently included a brief statement about the IOD on their ENSO Wrap-Up site:
I think we can do much more to deliver timely and targeted seasonal climate information to end-users, but this is a start, at least for SE Australia. And there are a number of web sites with more general forecast information (such as IRI and APEC).
Dr Peter McIntosh
Centre for Australian Weather and Climate Research
15 June 2008, Cai wrote:
TRIMM and QuikSCAT anomalies show that pIOD appears to have established itself over the past weeks. See figure below. After the development of easterly anomalies in April and May, the IOD grows really rapidly.
The question is should we tell anyone else (beyond this group) about it? This is a similar kind of debate to last year.
Centre for Australian Weather and Climate Research/CSIRO
13 June 2008, Jing-Jia Luo wrote:
Dear Sensei and colleagues,
Please find the attached PPT for FRCGC/JAMSTEC seasonal forecasts
initiated from 1 June 2008. La Nina is ending, and a weak warming
event might appear late this year. A strong positive IOD would occur
again this summer and fall, following the two positive IODs in 2006
and 2007. This IOD event might again cause extreme climate anomalies in
broad areas. Please keep close watching on its evolution.
If you have any comments/suggestions, please kindly inform us. Thank
you very much.
17 April 2008, Toshio Yamagata wrote:
Dear Mr. Hunt:
I have attached our forecast results prepared by Dr. Jing-Jia Luo in our team. It is very unfortunate but our SINTEX-F model run by the Earth Simulator predicts rather dry confitions in al least next three months as attached in the first ppt file. This is because the model, as an ensemble mean, predicts a weak positive IOD again in this year as shown in the second ppt file. La Nina still exists in the equatorial Pacific but it is getting weaker; we cannot expect its good influence over the south east Australia this year.
I hope our prediction will be wrong.
Best wishes, Toshio Yamagata
16 April 2008, Hunt Peter wrote:
Farmers in south-east Australia (Victoria and southern NSW) are desperate for rain after two years of drought
I have examined your latest SST and predicted rainfall for JJA and SON 2008
It seems SSTs will not rise sufficiently in the Indian Ocean to affect South-east Australian rainfall until SON.
The JJA rain map seems to indicate little rain in the south-east of Australia, although the resolution is low at this level.
Could you tell me when you think South-east Australia will receive good rain?
Regards and thanks
The Weekly Times