ANNUAL CLIMATE SUMMARY 2011 ANNUAL CLIMATE SUMMARY 2011 Annual Climate Summary 2011 © Commonwealth of Australia 2012 Contents This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Bureau of Meteorology. Requests and inquires concerning reproduction and rights should be addressed to the Publishing Unit, Bureau of Meteorology, GPO Box 1289, Melbourne 3001. Requests for reproduction of material from the Bureau website should be addressed to AMDISS, Bureau of Meteorology, at the same address. 1. Overview 1 2. Capital city summary 4 ISSN 1837-8854 3. Rainfall and temperature extremes by State 5 4. Monthly maximum temperatures 6 This document is also available online: www.bom.gov.au/climate/annual_sum/annsum.shtml 5. Monthly minimum temperatures 8 This edition is based on data available as of 20 January 2012. 6. Monthly distribution of rainfall deciles 10 7. Monthly rainfall totals 12 8. Annual rainfall deciles and totals 14 9. Annual review and significant events 15 10. Oceans: sea level and sea-surface temperatures 22 COVER PICTURE: Bushfire at Yamba Station, 16 October 2011, approximately 50 km north-northwest of Alice Springs. Picture courtesy of Northern Territory Police Fire and Emergency Services E-Magazine—The DRUM. Article: The red centre burns by Chief Fire Officer Steve Rothwell, 14 November 2011. ii iii Annual Climate Summary 2010 1. Overview First cooler-than-average year Cool years have been rare in the last three decades; since 2001 long-term temperature trends since the 1950s show Australia’s climate is warming. The ten-year average for For the first time in a decade, Australia’s annual mean 2002–2011 was the equal-warmest ten-year period on temperature was below the 1961–1990 average*. Cooler record for Australia (0.52 °C above average). temperatures in Australia are typically associated with high rainfall. The last cooler-than-average year was 2001, While 2011 was 0.14 °C below the 1961–1990 climato- which, like 2010, was a La Niña year with well-above- logical average of 21.81 °C, it ranks slightly above the average rainfall. median (52nd percentile) of all observations since 1910. Heavy rainfall at the start and end of the year, and Australia experienced three notable heatwave events frequent southerly wind flow in the first half of the year, during 2011; the first from late January to early February suppressed temperatures over much of the mainland. across the southern mainland, the second during early Averaged over Australia, the annual mean temperature August across southeastern Australia, and the third in for 2011 was 21.67 °C. northwestern Australia at the end of December (see section 9 on page15). While 2011 was cooler than average for Australia as a whole, below-average temperatures were mostly confined to northern Australia; southern Australia was Globally, warmest La Niña year warmer than average. on record Overnight warmth was especially notable in parts of Using three separate datasets, the World Meteorological southern Western Australia and South Australia where Organization ranked 2011 as the equal-tenth-warmest annual average minimum temperatures were highest year on record. The global combined sea-surface and on record. Annual average maxima were also highest on land air temperature for 2011 was 0.41 °C, ± 0.11 °C, record along the southern west coast of Western Australia. above the 1961–1990 annual average of 14.0 °C. No year since 1985 recorded a below-average global mean For Australia overall, maxima were 0.25 °C below average, temperature, and the 13 warmest years on record all while minima were 0.03 °C below average. January, occurred in the last 15 years. The ten-year global average July and August temperatures were well above average, from 2002–2011 was +0.46 °C above average, making it excluding the tropics. Cool maxima were widespread the equal-warmest such period on record. between February and May, while December was very cool for New South Wales. Minima were very much below Of the 23 climate regions monitored by the WMO average during May and June over northern Australia. globally, northern Australia was the only region to record 1.5 Annual and decadal mean temperature 1.0 Decadal mean anomalies (1910–2011) for Australia. The 0.5 average value for the most recent 0 10-year period (2002–2011) is shown -0.5 in darker orange. -1.0 Mean temperature anomalies (°C) -1.5 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 Year Satellite-aquired image from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite (http://earthobservatory.nasa.gov/IOTD/view.php?id=52361). It shows large fires (marked in black) burning throughout *Unless otherwise stated, all climatological averages are calculated over the 30-year period from 1961–1990, as recommended by the World Meteorological Organization. Anomalies are defined as the difference between the observed temperature and the corresponding the Northern Territory on 30 September 2011. The fire season in 2011 proved to be one of the most extreme in recent average over the reference period 1961–1990. years for the arid regions. La Niña rains in 2010 and early 2011 allowed thick grass to grow across Australia’s normally dry interior. The grass dried over winter and was an abundant fuel source. iv 1 Annual Climate Summary 2011 Overview cooler-than-normal temperatures during 2011, associated 900 Australian annual and with the very heavy rainfall. Decadal mean decadal mean rainfall 800 (1900–2011). The Due to the exchange of heat between the atmosphere 700 average value for the and oceans, years commencing with a strong La Niña most recent 10-year have surface temperatures (the temperature of the 600 period (2002–2011) is lower atmosphere) that are typically 0.10 to 0.15 °C shown in darker blue. 500 cooler than the preceding and following years. Although global temperatures were not as warm as the record- 400 breaking values seen in 2010, 2011 was the warmest Annual rainfall (mm) 300 La Niña year on record globally. 2011 was considerably warmer than the most recent moderate-to-strong 200 La Niña years: 2008 (+0.36 °C), 2000 (+0.27 °C) and 100 1989 (+0.12 °C). For Australia, 2008 was the warmest 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 year commencing with a La Niña on record (+0.41 °C). Year A tale of two La Niñas—Australia’s Capital cities reduced cool weather frequency continued in 2011. Ending on 6 February, Sydney experienced its longest All capital cities (see page 4), except Darwin, recorded wettest two-year period on record hot spell in 152 years of record with seven consecutive warmer-than-average maximum temperatures, while The Australian mean rainfall total for 2011 was 705 mm, days above 30 °C and five nights above 24 °C. On 6 Darwin, Brisbane and Canberra recorded cooler than 240 mm above the long-term average of 465 mm, February, Sydney also had its highest daily minimum average minima. Perth was notable for its warmth, the placing the year at second-wettest since records began temperature (27.6 °C). Sydney’s lowest minimum (7.3 °C, only capital to record an anomaly greater than 1 °C in 1900. Back-to-back La Niña events led to a two-year 11 August) and lowest maximum (16.5 °C, 14 August) above average, for both maxima and minima. Annual rainfall total of 1408 mm, the highest two-year total on were the highest recorded for August. average maxima for Perth were the warmest in 114 record, surpassing 1407 mm in 1973–1974. years of record. Adelaide recorded the highest capital Daytime temperatures for Perth in February were all 2011 rainfall as a percentage of the 1961–1990 annual average. The 2010–2011 La Niña, one of the strongest on record, city maximum temperature in 2011, with 42.9 °C on 31 above 29.6 °C, something that has not occurred since brought above-average rainfall during the second half January. The lowest capital city temperature was –8.0 °C at least 1910. The March average daily maximum of 2010 and the first part of 2011, before decaying in in Canberra on 29 July, the coolest night in Canberra since temperature (31.9 °C) was the highest on record, with a autumn. As has occurred several times in the historical 1994. All capital cities, except Adelaide, Brisbane and record period of 22 consecutive days exceeding 30 °C. record, La Niña conditions redeveloped during spring, Canberra, exceeded their long-term annual median rainfall. Hobart’s lowest November maximum (16.1 °C, with a second, weaker event continuing into summer Darwin reached 2693 mm, its second-highest annual 2 November) was the warmest on record for the 2011–12. total on record, after 1998. Hobart recorded the highest month’s coolest day, while its August average daily number of rain days, 183; and Perth the fewest, 106. The majority of Australia received very-much-above- minimum temperature (8.1 °C) was the highest on average rainfall for 2011. Large areas of highest-on- As well as being a warmer-than-average year over the record for the month. It was the first November in record totals fell in the Kimberley, southeastern Western southern part of the continent, the general trend of greatly Melbourne with no nights below 10 °C. Australia and across the north of the Northern Territory. For Western Australia, it was the wettest year on record and third-wettest for the Northern Territory. Rainfall (mm) Maximum temperature (°C) Minimum temperature (°C) The 2010–2011 La Niña was characterised by numerous 2011 Normal Rank 2011 Normal Rank 2011 Normal Rank and significant floods continuing throughout summer total 1961–90 (of 112) anomaly 1961–90 (of 102) anomaly 1961–90 (of 102) 2010–11 and into autumn.