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Southern Hemisphere Annular Mode (SAM) Index..AAO

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SAM ( southern annular mode) Also referred to as the Antarctic Oscillation ( AAO )

TIME SERIES

The SAM was trending positive from 1965 to 1999

SAM 1960 to 2010

SOME LINKS AND RESOURCES TO UNDERSTANDING THE SOUTHERN ANNULAR MODE
I will add to this list in the future
Feel free to post a comment on any information and links on the SAM.

TIME SERIES
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/aao/month_aao_index.shtml
SAM time series

Of particular interest in the graph below …!!
is the hockey stick curve of positive SAM in the winter season data.

Since 2007/2008 the SAM has climbed ‘exponentially toward 2010.!!!

Notice this extreme positive phase is a seasonal anomaly for the SH winter period of JUNE/JULY/AUGUST.

In fact the summer and annual anomaly has levelled off or maybe even declined since 1998

1998 is considered as the maximum of the modern warm period by some cycle researchers.. Will the winter SAM start dipping negative as well?

Intuitively you would suspect a persistent negative SAM trend would be needed for a period of global cooling..?

…………The SAM index. SEASONAL..
Top.(.SUMMER. DJF 1947-2010)
Middle.( WINTER JJA ..1948-2010)
Bottom. (ANNUAL 1948-2010)

The yellow lines indicate 7-year Gaussian-type filtered values.
time series of SAM

RESOURCE LINK from
http://www.lasg.ac.cn/
Is There a Relationship between the SAM and Southwest Western …
http://www.lasg.ac.cn/UpLoadFiles/File/papers/2010/2010_JCLI_Feng_Li_Li.pdf

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CURRENT SAM/AAO ANOMALY

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/verf/new.aao.shtml

CURRENT AAO index

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      • ‘SNOWMI’ on a NEW AUSTRALIAN FORUM has constructed a discussion thread titled

“Cold Front Activity Controls and Trends”

‘Snowmi’ has commenced discussion on the links to the SAM index and cold fronts across Australia

You can follow and join the discussion here
http://www.weather.liway.com/forums/viewtopic.php?f=6&t=4

You may have to register to view the discussion.
http://www.weather.liway.com/forums/index.php

This is a new weather and climate forum based in Australia since July 2013
The forum was developed as a result of the’ weatherzone forum’ closing its climate debate section which left contributors ‘short changed’ and bereft.
The owner of the forum ..’GB’..like myself felt a need to replace the hole that was left by the Weatherzone decision.
http://forum.weatherzone.com.au/

I thank ‘snowmi’ ( a moderator and contributor at the http://www.weather.liway.com forum)for posting the excellent link of the time series data for the SAM

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9 comments on “Southern Hemisphere Annular Mode (SAM) Index..AAO

  1. Thanks to Ken Kato for easily understood info’ on the SAM/AAO
    where it is being discussed on weatherzone forum.
    http://forum.weatherzone.com.au/ubbthreads.php/topics/1498946/103

    “The AAO is the antarctic oscillation index also known as SAM (southern annular mode) and in simple terms, it’s basically an index to measure how far north or south the main belt of midlatitude westerlies circling the southern hemisphere is at any given time.

    During a positive phase of the AAO/SAM, the main westerly belt together with the associated midlat lows/fronts contracts further south which often (but not always) leads to lower rainfall over some southern parts of Australia in winter (but this can also encourage more troughiness/lower pressures/onshore flow and enhanced rainfall in some areas further north in the summer months as highs dip further south as well).
    Conversely, a negative phase results in the main westerly belt and lows/fronts moving further north and often leads to higher rainfall in some southern parts of Australia as well as more frequent cold W to SW outbreaks.

    Naturally, just like any other climate driver, +ve and -ve SAM phases don’t always result in the above effects on rainfall and there’s always exceptions due to many other influences e.g. a strong -ve phase doesn’t always result in big cold fronts and lows surging up over all of the southern half of Australia and every area getting good rainfall because the entire westerly belt doesn’t extend northwards evenly over the whole southern hemisphere.
    There’s also some research to suggest that there may be a weak but statistically significant correlation between SAM and ENSO phases in summer. Also need to be careful of associating big cutoff lows in the winter months with a -ve SAM because those systems are cut off from the main westerly belt and often wander further north than lows within the westerly belt.”

    Image 1 above – Map showing which climate driver affects which area the most in different seasons. Red = blocking systems, yellow = SAM, turquoise = Dipole Mode Index (the Indian Ocean Dipole), violet = SOI.
    Map from the publication “On the Remote Drivers of Rainfall Variability in Australia” (Risbey, Pook, McIntosh, Wheeler, 2009).

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