1 CUTTING-EDGE CLIMATE SCIENCE AND SERVICES Geoff Love

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CUTTING-EDGE CLIMATE SCIENCE AND SERVICES

Geoff Love

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An essential task of the climate researcher is to increase our understanding of the climate we experience. In climate science there is a history of researchers using data sets to identify statistical relationships between variables. The science challenge is to understand why there is a correlation and to use that information in a predictive sense.

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A fundamental conundrum in meteorology is that we have good predictability for about 5 to maybe 7 days in the mid-latitudes. But beyond that not a lot of skill in forecasting – and what we do have is probably due to tropical forcing.

Whereas, in the tropics, short term predictability is low. Forecasters rarely beat persistence on 1 - 3 day time-scales unless there is a major synoptic event like a tropical cyclone. However, on longer timescales (of the order of a month and beyond), low, but positive skill is provided by a variety of tropical features.

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Mid-latitude weather forecasts have reasonable accuracy out to a maximum of two weeks (currently somewhat less).

Seasonal forecasts, on timescales of 1 month to 1 year have lower skill than weather forecasts and have higher skill in the tropics.

Scenarios for climate change on timescales of greater than 1 year are informed by changing composition of the atmosphere – a feature that is reasonably well predicted.

PR

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AB

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YMid-latitudes Tropics Global

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The cutting-edge science questions this arrangement of the atmosphere (clouds, clear bits, moisture, thunderstorms, winds, etc) poses are:

• What are the time and space scales of organisation?

• Why are they like that?

• How can we represent these in models of the atmosphere?

• What do we have to measure to: (1) specify the significant parts of the atmosphere properly, and (2) how should we analyse these observations so that our predictive models can make best use of our observations?

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Matt Wheeler’s answer is that the atmosphere (and the tropical bit in particular) is made up of a zoo of propagating waves.

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 CHANGING LARGE-SCALE PATTERNS

Over the period 1950 to 2003 there appears to have been a systematic change in temperature and rainfall

Temperature anomaly

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ANOTHER LARGE-SCALE FEATURE IS THE WALKER CIRCULATION

The Walker Circulation – the schematic circulation between South America and Southeast

Asia/North Australia

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So, is the Walker Circulation responding to these changes in global temperature?

It seems to me to be a cutting edge science question to answer this.

An El Nino event is a weakening of the Walker Circulation, a La Nina event a strengthening. There are many systems, both statistical and dynamical that attempt to model, in a predictive sense, this Circulation.

To succeed in modelling the Walker Circulation, so that we could predict its changes, would be a cutting-edge scientific achievement.

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The Bureau of Meteorology operates the POAMA system, and using it routinely produces an ensemble of predictions for the strength of the Walker Circulation.

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 ENSO AND EXTREME EVENTS

Average annual number of tropical cyclones in 2o X 2o grid boxes (1969 – 1998 climatology).

In the La Nina years there are more tropical cyclones, and they are closer to the Australian coastline, than in the El Nino years.

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The story of Australian climate, and particularly rainfall, is closely tied to what happens with the El Nino / La Nina cycle.

RAINFALL AND ENSO

Variability of Annual rainfall

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Australia S. Africa Germany France NZ India UK Canada China USA Russia

Country

Coe

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El Nino

La Nina

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RAINFALL AND EL NINO 

THE EL NINO YEARS1902-1903, 1905-1906, 1911-1912, 1914-19151918-1919, 1923-1924, 1925-1926, 1930-19311932-1933, 1939-1940, 1941-1942, 1951-19521953-1954, 1957-1958, 1965-1966, 1969-19701972-1973, 1976-1977, 1982-1983, 1986-19871991-1992, 1994-1995, 1997-1998

23 El Ninos in the past 100 years, 11 to 1950 and 12 since.

Composite pictures of the summer and winter rainfall anomalies for the twelve most significant El Ninos.

summer

winter

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RAIN AND LA NINA 

THE LA NINA YEARS: 

1904-1905 , 1909-1910, 1910-1911, 1915-19161917-1918, 1924-1925, 1928-1929, 1938-19391950-1951, 1955-1956, 1956-1957, 1964-19651970-1971, 1971-1972, 1973-1974, 1975-19761988-1989 , 1995-1996

18 La Ninas in the past 100 years, 9 up to and including 1950, and 9 since.

Composite pictures of the summer and winter rainfall anomalies for the twelve most significant La Ninassummer

winter

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SCENARIOS FOR RAIN AND TEMPERATURE

The yellow ellipse encompasses 95% of the 1000 year unforced runs projections of temperature and precipitation for the Northern Australian region of the Canadian CGCM2 model.

The blue ellipse is from the UK Hadley Centre HadCM3 model.

About 1oC warming and 15% more rainfall in the north in summer.

Northern Australia extends from the north coast to 30oS.

Blue – HadCM3

Yellow - CGCM2

SUMMER - NORTH

Source: Ruosteenoja, Carter, Jylha and Tuomenvirta, “ Future climate of world regions: an intercomparison of model-based projections for the new IPCC emission scenarios”. Pub: Finnish Environment Institute. Helsinki 2003.

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SCENARIOS FOR RAIN AND TEMPERATURE

About 1oC warming and no change in rainfall in the north in winter.

Blue – HadCM3

Yellow - CGCM2

WINTER - NORTH

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SCENARIOS FOR RAIN AND TEMPERATURE

Blue – HadCM3

Yellow - CGCM2

SUMMER - SOUTH

About 1oC warming and maybe slightly more rainfall in the south in summer.

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SCENARIOS FOR RAIN AND TEMPERATURE

Blue – HadCM3

Yellow - CGCM2

WINTER - SOUTH

About 1oC warming and no change in rainfall in the south in winter.

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For broad scale scenarios to be truly useful they need to be down-scaled so as to inform private individuals, farmers, fishers and small- and large-business operators how climate, climate change and climate variability will affect them.

Accurate, verifiable downscaling is cutting-edge science

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After developing scenarios for climate change and downscaling these they must be extended to better understand impacts on biological and economic systems (most particularly on global trade and national energy policy).

High quality Earth-system simulation is cutting-edge science

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CLIMATE SERVICES

Annual Hits on the Bureau of Meteorology's Climate Web Pages

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MillionMust be what the user community needs and wants

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THE MOST POPULAR PRODUCTS

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THE MOST POPULAR PRODUCTS #1

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THE MOST POPULAR PRODUCTS #2

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THE MOST POPULAR PRODUCTS #3

Temperature

Temperature anomaly

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THE MOST POPULAR PRODUCTS #4Other charts; eg NDVI and various

seasonal timescale forecast products

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WHAT ELSE ?

Climate service users want:

• More data – radar, observations, predictions;

• Local scale information;

• Simple explanations or explanations of likely uncertainties; and

• Forecasts at the scale of their enterprise with long lead times and high accuracy.

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THE FUTURE CUTTING EDGE SERVICE ?

Cutting edge services will continue to make good use of the most up-to-date science to develop products and the best technologies to deliver these services.

Cutting edge services will inevitably follow the delivery of cutting edge science

The cutting-edge service will develop partnerships to form the link between scientists and users throughout the community.

THANK YOU