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Drivers of Climate at Mildura Dale Grey DPI Cobram Mildura Cropping Agronomist Tuesday, 29 th June 2010.

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Presentation on theme: "Drivers of Climate at Mildura Dale Grey DPI Cobram Mildura Cropping Agronomist Tuesday, 29 th June 2010."— Presentation transcript:

1 Drivers of Climate at Mildura Dale Grey DPI Cobram Mildura Cropping Agronomist Tuesday, 29 th June 2010

2

3 Annual

4 Annual- 5 year moving average Federation WWII

5 Summer Autumn Winter Spring

6 Autumn demise Summer Winter

7 Autumn Top of the Goulburn Catchment

8 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.

9 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.

10 Factors affecting Climate at Mildura El Niño / La Niña Indian Ocean Dipole IOD (+/-) Southern Annular Mode SAM (+/-) Sub Tropical Ridge STR Madden Julian Oscillation (phases 1-8) Pacific Decadal Oscillation (+/-) North West Cloud Bands Cut Off Lows

11 Word for the Day Anomaly- deviation from normal

12 First Some Oceanography 101

13 RAMA Satellite Argo Robotic Buoy Ships of Opportunity

14 29 o C 13 o C

15 Young Endeavour, March 2006 “The Rip” taken by M.Pardy

16 November 2006 Cold off Darwin-Qld El Niño El Niño surface temperature anomaly

17 December 31st 2007 Warm off Darwin-Qld La Niña Classic horseshoe shape of warm water for La Niña

18 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 negative La Niña The opposite

19 Thermocline flat PNG Ecuador El Niño Sub-surface

20 Thermocline sloped La Niña Sub-surface

21 World Cloudiness, 2002 El Niño Becomes cloudier at the dateline cloudy clear

22 World Cloudiness La Niña Lack of cloud at the date line cloudy clear

23 Equatorial Wind El Niño top, trade winds switch to the West La Niña bottom, winds strengthen to the East

24 Worldwide effects of La Niña and El Niño El NiñoLa Niña El Niño La Niña

25 Indian Ocean Dipole Positive (IOD +ve)

26 Indian Ocean Dipole Negative (IOD -ve) No IOD- since 1992

27 August 2006 IOD+ Cool Broome-Brisbane

28 September 26th 2007 IOD+ Weak one

29 June 30th 2008 IOD+ Cool Broome-Brisbane

30 September 29th 2008 IOD’s tend to decay from east to west in late September-October

31 16 years 23 years El niño 19 years La niña 27 years

32 16 years 20 years El niño 17 years La niña 24 years

33 photo taken by a QANTAS navigator above Sydney Oct 2009

34 PNGEcuador 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

35 Decreasing cloud around the International Date Line = la Nina The Coral seas is still less cloudy. Indonesia has remained cloudy for the last 3 months Victoria is normal cloudy clear

36 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

37 In early November the Coral and Arafura sea cooled off as a result of the plunging SOI in Oct. The long awaited el Niño was finally fully coupled. This led to the much maligned fry up. November 16 th 2009 El Niño

38 December 31 st 2009 El Niño peaks. At Nino 3 and 3.4 areas of the Pacific were 1.5 and 1.9 o C warmer. Much of the ocean to the north was warm. There was a lack of gradient in the Indian Ocean. El Niño

39 Currently the Nino 3, 3.4 and 4 areas of the Pacific are -0.35, and o C warmer, near the -0.8 threshold. The DMI measurement of the IOD is which is neutral. x x June 24 th 2010

40 Harvest time, North Dakota Oct 2009

41 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 40 o and 65 o degrees latitude

42 The Southern Annular Mode (AAO) was more negative for the 2009 winter spring year. Negative SAM Polar winds weaker Westerlies closer to Southern Aus Pushes fronts more northward. But changes weekly and isn’t the absolute cause of rain in the south

43 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 haven’t really affected Victorian rainfall.

44 Most of the upward trend is over Summer and Autumn

45 13 years -SAM 10 years +SAM

46 13 years -SAM 10 years +SAM

47 The Sub tropical ridges originate as a result of the Hadley Cells emanating from the Equator. One in each hemisphere, dry descending air causing high pressure. Mediterranean climates and deserts occur in these regions of the world. Sub-tropical ridge

48 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

49 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

50 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.

51 Increased high pressure systems in the last 50 years

52 27 years 28 years 30 years

53 24 years 20 years 30 years

54 A January 2010 day at Metung

55 The latest “Fast Break” analysis for the next three months Pacific cool (La nina) Indian slightly warm Rainfall Average-slightly wetter Slightly warmer temps

56 The “Fast Break” analysis for four to six months Pacific cool (La nina) Indian slightly warm Rainfall Slightly wetter Average- slightly warmer temps

57

58 Thankyou See me to Subscribe to “The Break”


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