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Drivers of Climate at Mildura

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

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Drivers of Climate at Mildura

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

  2. Annual

  3. WWII Federation Annual- 5 year moving average

  4. Summer Autumn Winter Spring

  5. Summer Autumn demise Winter Spring

  6. Top of the Goulburn Catchment Autumn

  7. Averaged over the whole year temperature doesn’t actually vary by that much. Mildura 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.

  8. 5 Year moving average of annual rainfall (Mildura) Previous droughts have not been as hot. 5 Year moving average of annual Max temp anomaly (Mildura)

  9. 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

  10. Word for the Day • Anomaly- deviation from normal

  11. FirstSome Oceanography 101

  12. Argo Robotic Buoy Satellite Ships of Opportunity RAMA

  13. 29oC 13oC

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

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

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

  17. The Walker CirculationA 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

  18. PNG Ecuador Thermocline flat El Niño Sub-surface

  19. La Niña Sub-surface Thermocline sloped

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

  21. cloudy clear World Cloudiness. 2007 La Niña Lack of cloud at the date line

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

  23. El Niño La Niña Worldwide effects of La Niña and El Niño El Niño La Niña

  24. Indian Ocean Dipole Positive (IOD +ve)

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

  26. August 2006 Cool Broome-Brisbane IOD+

  27. September 26th 2007 IOD+ Weak one

  28. June 30th 2008 Cool Broome-Brisbane IOD+

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

  30. El niño 19 years 23 years 1890-2010 La niña 27 years 16 years

  31. El niño 17 years 20 years 1901-2010 La niña 24 years 16 years

  32. photo taken by a QANTAS navigator above Sydney Oct 2009

  33. 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

  34. cloudy clear 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

  35. The SOI has ants in its pants el Niño warning November fry up Cyclone Oli Southern Oscillation Index = SOI = difference in air pressure (Tahiti – Darwin)

  36. November 16th 2009 El Niño 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.

  37. December 31st 2009 El Niño 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.

  38. June 24th 2010 x x Currently the Nino 3, 3.4 and 4areas 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.

  39. Harvest time, North Dakota Oct 2009

  40. The SAM index is calculated by the differences in pressure between 40o and 65o degrees latitude Southern Annular Mode, SAM or AAO Measures the strength of polar westerlies in the Southern Ocean.

  41. 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

  42. 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.

  43. Most of the upward trend is over Summer and Autumn

  44. 10 years +SAM 1957-2010 13 years -SAM

  45. 10 years +SAM 1957-2010 13 years -SAM

  46. Sub-tropical ridge 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.

  47. July 2009 Winter pattern, centre of highs over the top of the Bight Jan 2009 Sub Tropical Ridge The High pressure belt lying over Australia and at all mid latitudes of the world. Summer pattern, centre of highs over Melbourne

  48. 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

  49. 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.

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