drivers of climate at mildura dale grey dpi cobram mildura cropping agronomist tuesday, 29 th june...
TRANSCRIPT
Drivers of Climate at Mildura
Dale Grey DPI Cobram Mildura Cropping Agronomist
Tuesday, 29th June 2010
Annual
Annual- 5 year moving average
FederationWWII
Summer Autumn
Winter Spring
Spring
Autumn demise
Summer
Winter
Autumn
Top of the Goulburn Catchment
Mildura
Averaged over the whole year temperature doesn’t actually vary by that much.
A 1 degree difference over a year is a massive change.
It could mean the equivalent of 38 extra winter days or 15 extra summer days crammed into the year.
-1.5
-1
-0.5
0
0.5
1
1.5
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
Tem
p A
no
m (
oC
)
5 Year moving average of annual Max temp anomaly (Mildura)
5 Year moving average of annual rainfall (Mildura)
Previous droughts have not been as hot.
Factors affecting Climate at Mildura
El Niño / La NiñaIndian Ocean Dipole IOD (+/-)Southern Annular Mode SAM (+/-)Sub Tropical Ridge STR
Madden Julian Oscillation (phases 1-8)Pacific Decadal Oscillation (+/-)North West Cloud BandsCut Off Lows
Word for the Day
Anomaly- deviation from normal
FirstSome Oceanography
101
RAMA
Satellite
Argo Robotic Buoy
Ships of Opportunity
29oC
13oC
Young Endeavour, March 2006 “The Rip” taken by M.Pardy
November 2006
Cold off Darwin-Qld
El Niño
El Niño surface temperature anomaly
December 31st 2007
Warm off Darwin-Qld
La Niña
Classic horseshoe shape of warm water for La Niña
The Walker Circulation A major influence on the Australian climate
El Niño
• Cool water north Australia
• Warm Pacific Ocean
• Weak easterly trade winds
• Convection near date line
• SOI negativeLa Niña
• The opposite
Thermocline flat
PNG Ecuador
El NiñoSub-surface
Thermocline slopedLa NiñaSub-surface
World Cloudiness, 2002 El NiñoBecomes cloudier at the dateline
cloudy clear
World Cloudiness. 2007 La Niña Lack of cloud at the date line
cloudy clear
Equatorial WindEl Niño top, trade winds switch to the WestLa Niña bottom, winds strengthen to the East
Worldwide effects of La Niña and El Niño
El Niño La Niña
El Niño La Niña
Indian Ocean Dipole Positive (IOD +ve)
Indian Ocean Dipole Negative (IOD -ve)
No IOD- since 1992
August 2006
IOD+
Cool Broome-Brisbane
September 26th 2007
IOD+
Weak one
June 30th 2008
IOD+
Cool Broome-Brisbane
September 29th 2008
IOD’s tend to decay from east to west in late September-October
Rainfall distribution (Aug-Oct) for IOD+ years Mildura
13%
26%
61%
>97mm
average mm
<52mm
Rainfall distribution (Aug-Oct) for IOD- years Mildura
62%
25%
13%
>97mm
average mm
<52mm
Rainfall distribution (Aug-Oct) for Jun-Jul SOI- Mildura
14%
19%
67%
>97mm
average mm
<52mm
Rainfall distribution (Aug-Oct) for Jun-Jul SOI+ Mildura
60%
28%
12%
>97mm
average mm
<52mm
16 years
23 years
1890-2010
El niño19 years
La niña27 years
Stream Flow distribution for IOD- years Mitta Mitta R (Hinnomunjie)
56%
38%
6%
>236,000 Ml
average ML
<176,000 Ml
Stream Flow distribution for IOD+ years Mitta Mitta R (Hinnomunjie)
5%
35%
60%
>236,000 Ml
average ML
<176,000 Ml
Stream Flow distribution (Aug-Nov) for Jun-Jul negative SOI, Mitta Mitta R (Hinnomunjie)
12%
12%
76%
>236,000 Ml
average ML
<176,000 Ml
Stream Flow distribution (Aug-Nov) for Jun-Jul negative SOI, Mitta Mitta R (Hinnomunjie)
67%
20%
13%
>236,000 Ml
average ML
<176,000 Ml
16 years
20 years
1901-2010
El niño17 years
La niña24 years
photo taken by a QANTAS navigator above Sydney Oct 2009
PNG Ecuador
We had progress of the cool counter current above the thermocline westwards.
Rapid breakdown from warm to neutral at the surface.
Thermocline now tilting.
Large cold anomalies at depth
Decreasing cloud around the International Date Line = la NinaThe Coral seas is still less cloudy.Indonesia has remained cloudy for the last 3 monthsVictoria is normal
cloudy clear
The SOI has ants in its pants
Southern Oscillation Index = SOI = difference in air pressure (Tahiti – Darwin)
November fry up
Cyclone Oli
el Niño warning
In early November the Coral and Arafura sea cooled off as a result of theplunging SOI in Oct. The long awaited el Niño was finally fully coupled.This led to the much maligned fry up.
November 16th 2009
El Niño
December 31st 2009
El Niño peaks. At Nino 3 and 3.4 areas of the Pacific were 1.5 and 1.9oC warmer. Much of the ocean to the north was warm.There was a lack of gradient in the Indian Ocean.
El Niño
Currently the Nino 3, 3.4 and 4 areas of the Pacific are -0.35, -0.42 and -0.02oC warmer, near the -0.8 threshold. The DMI measurement of the IOD is +0.12 which is neutral.
x x
June 24th 2010
Harvest time, North Dakota Oct 2009
Southern Annular Mode, SAM or AAO
Measures the strength of polar westerlies in the Southern Ocean.
The SAM index is calculated by the differences in pressure between 40o and 65o degrees latitude
The Southern Annular Mode (AAO) was more negative for the 2009 winter spring year.
Negative SAMPolar winds weakerWesterlies closer to Southern AusPushes fronts more northward.But changes weekly and isn’t the absolute cause of rain in the south
SAM has been positive for the last 6 weeks There is more usefulness in the SAM during winter.Its more positive Autumn in the last 25 years has been partially blamed for poor Autumns.
+SAM can significant lead to a wetter summer in E Gippsland.
The up and downs over summer in 2009-10 haven’t really affected Victorian rainfall.
Average Yearly SAM index
-2.00
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
2.0019
55
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
Year
SA
M
Most of the upward trend is over Summer and Autumn
Winter rainfall distribution in years of +SAM Jun-Aug Mildura
10%
20%
70%
>89mm
average mm
<59mm
Winter rainfall distribution in years of -SAM Jun-Aug Mildura
39%
38%
23%
>89mm
average mm
<59mm
13 years-SAM
10 years+SAM
1957-2010
Winter rainfall distribution in years of +SAM Jun-Aug Mitta Mitta R
20%
30%
50%
>120459ML
average ML
<80497ML
Winter rainfall distribution in years of -SAM Jun-Aug Mitta Mitta R
47%
38%
15% >120459ML
average ML
<80497ML
13 years-SAM
10 years+SAM
1957-2010
The Sub tropical ridges originate as a result of the Hadley Cells emanating from theEquator.One in each hemisphere, dry descending air causing high pressure.
Mediterranean climates and deserts occur in these regions of the world.
Sub-tropical ridge
Sub Tropical Ridge
July 2009
Winter pattern, centre of highs over the top of the Bight
Jan 2009
The High pressure belt lying over Australia and at all mid latitudes of the world.
Summer pattern, centre of highs over Melbourne
The Sub Tropical Ridge for the month of May was normally positioned and pressure was lower than normal, the ridge down to Tasmania wasn’t helpful
For most of the month of June the STR has been in a favourable position but the strength of the high pressures has been greater.
Increased high pressure systems in the last 50 years
Intensity of the STR and Global Warming(11-years running means)
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
0.40
0.60
0.80
1.00
Central Year
Pre
ss
ure
in h
Pa
-0.6-0.5-0.4-0.3-0.2-0.10.00.10.20.30.40.50.6
De
gre
e (
in C
els
ius
)
STR Intensity annual mean
Global Annual Temperature
Winter rainfall distribution in years of LOW Winter STR pressure, Mildura
54%
32%
14% >89mm
average mm
<59mm
Winter rainfall distribution in years of HIGH Winter STR pressure, Mildura
20%
13%
67%
>89mm
average mm
<59mm
Winter rainfall distribution in years of NORTH Winter STR position, Mildura
48%
37%
15% >89mm
average mm
<59mm
Winter rainfall distribution in years of SOUTH Winter STR position, Mildura
22%
15%63%
>89mm
average mm
<59mm
27 years
27 years
28 years
30 years
Winter rainfall distribution in years of LOW Winter STR pressure, Mitta Mitta R
(Hinnomunjie)
45%
35%
20%
>120459ML
average ML
<80497ML
Winter rainfall distribution in years of HIGH Winter STR pressure, Mitta Mitta R
23%
20%
57%
>120459ML
average ML
<80497ML
Winter rainfall distribution in years of NORTH Winter STR position, Mita Mitta R
59%
33%
8% >120459ML
average ML
<80497ML
Winter rainfall distribution in years of SOUTH Winter STR position, Mitta Mitta R
17%
38%
45%
>120459ML
average ML
<80497ML
24 years
24 years
20 years
30 years
1901-2010
A January 2010 day at Metung
The latest “Fast Break” analysisfor the next three months
Pacific cool (La nina)Indian slightly warm
Rainfall Average-slightly wetterSlightly warmer temps
The “Fast Break” analysisfor four to six months
Pacific cool (La nina)Indian slightly warm
Rainfall Slightly wetterAverage- slightly warmer temps
Thankyou
See me toSubscribe to“The Break”