Teleconnections between climate drivers and regional climate, and model representation of links

Final Report on the Managing Climate Variability project for GRDC

Principal investigator Peter McIntosh

Co-investigators

Mike Pook and James Risbey

CSIRO Climate Adaptation Flagship Centre for Australian Weather and Climate Research

CSIRO Marine Laboratories GPO Box 1538, Hobart 7001

June 2013

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Contents

Contents .................................................................................................................................................. 2 Project Summary ..................................................................................................................................... 3 Outcome Benefits .................................................................................................................................... 3 Overview ................................................................................................................................................. 4 Conclusions .............................................................................................................................................. 5 Recommendations .................................................................................................................................. 7 Response to Objectives ........................................................................................................................... 8

1. Science reports documenting the synoptic climatology of the major grain areas of Australia. These reports will outline how much different types of synoptic system contribute to rainfall in particular regions. ............................................................................................................................. 8

2. Science reports describing the major drivers of rainfall variability in the grain regions and the manner in which they connect to rainfall. ........................................................................................ 9

3. Science reports evaluating model performance of remote drivers and teleconnections. ............. 10 Output ................................................................................................................................................... 11

Publications ........................................................................................................................................ 11 Presentations and Media ................................................................................................................... 12

Acknowledgements ............................................................................................................................... 14 List of Attachments ............................................................................................................................... 14 References ............................................................................................................................................. 14

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Project Summary

Rainfall is delivered to the grain-growing regions of Australia primarily by cutoff lows and fronts. The relative proportions differ from east to west, as does their contribution to rainfall trends. The key drivers are the hemispheric long-waves, including the regional configuration of atmospheric blocking, and Indian Ocean processes. Blocking highs and cutoff lows form a blocking dipole, with the strength of blocking controlled mainly by land-sea temperature contrasts, and more generally by meridional temperature gradients. The temperature signal is conveyed into the upper atmospheric jet-streams by the agency of the thermal wind. The intensity of weather systems in the Bight is affected by the configuration of the long-wave pattern, and Indian Ocean temperatures and associated atmospheric convection. The teleconnection process is through atmospheric Rossby waves. Climate models including POAMA have difficulty representing both blocking and Rossby waves accurately.

Outcome Benefits

Previous research established that cutoff lows contributed about 50% of rainfall to the grain-growing regions of southeast Australia in the cool season, while fronts contributed about 33%. Cutoff lows are associated with atmospheric blocking, which is not well-represented by climate models. This project establishes that the percentages are reversed for the southwest grain-growing region, with fronts contributing 50% and cutoffs 33%. Furthermore, rainfall trends and variability are mainly associated with cutoff lows in the southeast, while in the southwest, cutoff lows and fronts make approximately equal contributions to the observed trends. The conclusion is that there are two dominant rainfall-producing weather systems that models must represent accurately. The importance of the Indian Ocean as a driver of rain-bearing weather systems in southern Australia has been demonstrated previously. It is not only the Indian Ocean dipole (IOD) that works this way, but also ENSO. The teleconnection mechanism has been conjectured to be simple propagation of atmospheric Rossby waves from the Indian Ocean but it has become clear from this project that there is also a more direct link between the remote climate drivers and the synoptic systems that produce rainfall. Specifically, changes in tropical sea surface temperatures (SST) near northern Australia and changes in Australian continental temperatures alter the meridional temperature gradients in the atmosphere and produce variations in the subtropical jet-stream via the thermal wind (e.g. Ummenhofer et al. 2008). This mechanism contributes directly to blocking intensity as well as influencing the formation and intensity of the synoptic systems which bring rainfall to southern Australia. Variations in the mid and high latitude jets are also related to variations in the Southern Annular Mode (SAM) and meridional temperature gradients south of Australia. Additionally, previous work has established that there is a Rossby wave teleconnection pathway from ENSO to the southeast Pacific and South American region. This teleconnection has been dubbed the PSA phenomenon. It is expressed as strong swings of polarity in the pressure pattern in the region with changes in the ENSO phase and it is conjectured that the resulting influence on the phase of the hemispheric long-waves may influence the configuration and intensity of the long-wave pattern and jets in the Australian region. This project has shown that the actual teleconnection mechanism is complicated, involving a Rossby wave barrier and conversion of energy into eddy-scale processes. It is shown that POAMA does not exhibit a large enough barrier, but it also does not generate enough Rossby wave energy out of the Indian Ocean. It is not clear whether these two features are related or independent, but in any event it points clearly to model features that must be improved to get better representation of weather systems in the grain growing regions.

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Cutoff lows are associated strongly with atmospheric blocking. Climate models have difficulty representing blocking accurately. This project has explored the reasons for this and concluded that the land-sea temperature contrast, model topography and tropical convection processes must be better modelled. In particular, this study links tropical ocean temperature anomalies through the Rossby wave teleconnection process to atmospheric blocking in the Australian sector. This project contributes to the long-term evolution of climate model skill. In the same way that weather forecasts have improved substantially over several decades, seasonal forecasts are now improving. The outcome is increased seasonal forecast skill that benefits all climate-sensitive sectors. The benefits are difficult to quantify, but it is known that the sensitivity of the Australian economy to climate variability is about $58 billion annually, which is about 5% of GDP.

Overview

The synoptic meteorology of the major grain growing areas in Australia has been synthesized and documented. The relative importance of the two dominant rainfall mechanisms (fronts and cutoff lows) has been shown to vary by region and season. Spatial plots of the proportional contribution of cutoff lows and fronts to total rainfall have highlighted the importance of cutoff lows in South Australia, NSW and eastern Tasmania, and the importance of frontal rainfall in SWWA. They also showed the variation of synoptic rainfall near coasts and over topography. These results underline the importance of understanding the synoptic influences on rainfall in different regions, particularly when remote drivers can affect the amount and trend of different synoptic types in different ways. For example, the downward trend in rainfall over the past decade is more likely to be associated with cutoff lows in the southeast, which in turn suggests that an examination of a related driver, atmospheric blocking, might prove fruitful. Diagnosis of synoptic systems is evolving from the original time-consuming manual analysis towards automated methods developed from and benchmarked against the manual results. An automated method for detecting cutoff lows has been developed and used to assess climate model simulations of cutoff lows. It is concluded that climate models have difficulty in simulating the number of cutoff low systems observed. There are a number of different methods for automatically detecting frontal systems, and these have been compared to the manual method in south western Australia. While the automated methods compare quite well with the manual analysis, there is room for improvement. The seasonal cycle of blocking and its relationship to rainfall via synoptic weather systems in the Australian region has been documented. The association between atmospheric blocking and rainfall through the mechanism of cutoff low synoptic systems in all seasons except summer has been confirmed. It is also shown that blocking has no significant correlation with rainfall due to fronts. The meridional temperature gradient in the Australian region, particularly the land-ocean temperature contrast, is identified as a probable controlling factor in blocking. Based on these hypotheses, many experiments have been conducted using a climate model driven by different heating patterns over the ocean and land. All climate models, including this one, appear to underestimate blocking in the Australian region. The experiments show the primary importance of warm tropical waters north of Australia and in the Indian Ocean. The teleconnection mechanism is related to atmospheric Rossby waves that are generated by tropical convection and propagate south-eastwards over the Great Australian Bight where they appear to enhance the strength of atmospheric high pressure systems. The sea surface temperature signal is also conveyed into the upper atmosphere by altering the atmospheric thickness and the resulting thermal wind which affects the subtropical jet, a key contributor to a local measure of blocking. The experiments also appear to underestimate the expected effect of land temperatures on blocking, which indicates that the land-surface component of climate models needs further study.

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Existing measures of blocking are based on simple local indices that may not adequately represent the long-wave structure. A new dynamically-based blocking index has been developed and compared with conventional indices. The new index represents the hemispherical spatial structure of blocking regimes and has been tested in observations and model data. The ACCESS model successfully captures blocking regimes using the new index, though transitions between blocking and zonal regimes are less frequent than in observations, and the spatial structure shows some differences. This is a new and evolving area of research. This project has concluded that, along with atmospheric blocking, one of the most important drivers to study in connection with southern Australian rainfall was the tropical Indian Ocean, a region where both ENSO and IOD-related convection anomalies generate atmospheric Rossby waves that propagate south-westwards over Australia. This is not to say that other drivers are unimportant, but Indian Ocean sourced Rossby waves and atmospheric blocking would appear to have the greatest influence on rainfall in the grain-growing regions. The precise nature of the dynamical teleconnection between the tropical Indian Ocean and southern Australia has been explored in observations and compared to the POAMA seasonal forecast model. The observations indicate a "no-go zone" south of Australia for the propagation of atmospheric Rossby waves travelling from the tropics. It appears that the Rossby waves convert their energy into synoptic-scale disturbances that then feedback on the large-scale flow. POAMA exhibits a smaller no-go zone further to the east, thus allowing Rossby waves an easier pathway. However, the model does not generate these waves, and it is conjectured that the no-go zone might be setup or maintained by breaking Rossby waves. In terms of model development, this points to the need for improvement in tropical Indian Ocean convection and the generation of atmospheric Rossby waves.

Conclusions

The two most important synoptic weather systems associated with rainfall in the grain growing regions of Australia during the growing season are cutoff lows and fronts. In the southeast of the country, cutoff lows account for 50% of the rainfall while fronts account for 33%. In the southwest these proportions are reversed. In the southeast, rainfall variability and trends are most closely related to cutoff lows, while both synoptic systems are implicated in the southwest. Cutoff lows are closely connected to atmospheric blocking, while fronts are not. Any comprehensive study of Australian rainfall in the grain growing regions must take these two synoptic systems and their individual controlling factors into account. Atmospheric blocking is clearly one of the important drivers of rainfall through its effect on cutoff lows. ENSO and the IOD are important tropical drivers that transmit their influence on weather in the southern half of Australia via atmospheric Rossby waves that are generated in the Indian Ocean and by altering the meridional temperature gradients in the vicinity of northern Australia. Other drivers are of less relevance to the grain growing regions in the cool season, although they may be important in other areas or at other times of the year. The way in which atmospheric Rossby waves influence weather in southern Australia is more complicated than had been conjectured. Rossby waves are unable to propagate simply into the Great Australian Bight region because there is a Rossby wave barrier there associated with the southern flank of the sub-tropical jet. The mechanism is more complicated, involving conversion of energy into eddy scales that then feedback on the mean flow to produce pressure anomalies that alter weather systems. Climate models must be able to simulate accurately the key weather systems and their drivers. However, it is shown that climate models generate only about half the number of cutoff lows that they should, and this is likely associated with the difficulty models have in simulating atmospheric

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blocking. The simulation of blocking appears to be related to the ability of the models to represent accurately the effect of land-sea temperature differences both in the sub-tropics and mid-latitudes. POAMA’s representation of the Rossby wave teleconnection process is inaccurate. The Rossby wave barrier is reduced considerably in size compared to observations, but there is little Rossby wave energy propagating down from the Indian Ocean into the region anyway. It is clear that climate models would benefit from a more accurate representation of tropical Indian Ocean and atmosphere processes such as convection. The atmosphere-ocean feedback necessary to sustain an independent Indian Ocean Dipole needs further examination. The land-surface temperature interaction with the atmosphere is another likely candidate for improvement. It is likely that advances in these areas would lead to a climate model with improved blocking, more cutoff lows and a more accurate representation of one of the key rainfall processes in the southern Australian region.

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Recommendations

The approach of diagnosing synoptic systems responsible for rainfall in observations and models has proven valuable in isolating drivers, causes of trends and variability, and model deficiencies. The method is labour intensive, and automated recognition methods have been developed. More work is needed to refine these automatic methods so that they apply across a range of climatic regions, and so that the various frontal methods are in better agreement. Climate models would benefit substantially from an improvement in their representation of a number of key processes. These models under-represent both cutoff lows and blocking. Furthermore, POAMA has a substantially reduced barrier zone for atmospheric Rossby waves from the Indian Ocean, and a reduced energy flux from Rossby waves coming from the same region. It is clear that climate models would benefit from a more accurate representation of the tropical Indian Ocean, atmosphere-ocean feedbacks, and associated atmospheric processes such as convection. The land-surface temperature interaction with the atmosphere is another area where improvement is likely to be beneficial, particularly to blocking and cutoffs.

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Response to Objectives

1. Science reports documenting the synoptic climatology of the major grain areas of Australia. These reports will outline how much different types of synoptic system contribute to rainfall in particular regions.

Synoptic weather systems are a fundamental building block of the climate system. Understanding the weather systems associated with rainfall is essential in understanding how remote climate drivers influence local rainfall. It is also a key component in understanding the strengths and weaknesses of climate models, and is a useful tool in communicating climate information in familiar terms. The synoptic climatology of the southeast Australian grain-growing region was developed by Pook et al. (2006). They found that rainfall in the grain-growing season Apr-Oct was associated with two main synoptic weather systems: cold fronts and cutoff lows. While the well-known cold front accounted for about one-third of the rainfall, a less well-known weather system known as a cutoff low accounted for about one half. It was further established that the occurrence of cutoff lows was associated with atmospheric blocking south and east of Australia. A similar study focussing on Tasmania confirmed the importance of cutoff lows for the east of the state, while highlighting the importance of the Tasmanian topography in altering the mix of synoptic systems over relatively short spatial scales (Pook et al. 2010). Another synoptic classification was conducted for the central wheat belt in Western Australia (Pook et al. 2012). Here the proportion of rainfall associated with the two major synoptic systems is reversed, with fronts accounting for one half and cutoff lows accounting for one third. However, the decline in rainfall over the past decade in particular was shown to be associated with a decline in cutoff lows and the associated atmospheric blocking. The synoptic climatology of the major grain-growing areas of Australia was synthesised and extended by Pook et al. (2013a). Of particular interest were summary spatial plots of the proportional contribution of cutoff lows and fronts to total rainfall. These highlighted the importance of cutoff lows in South Australia, NSW and eastern Tasmania, and the importance of frontal rainfall in SWWA. They also showed the variation of synoptic rainfall near coasts and over topography. These results underline the importance of understanding the synoptic influences on rainfall in different regions, particularly when remote drivers can affect the amount and trend of different synoptic types in different ways. For example, the downward trend in rainfall over the past decade is more likely to be associated with cutoff lows in the southeast, which in turn suggests that an examination of a related driver, atmospheric blocking, might prove fruitful. Diagnosis of synoptic systems is evolving from the original time-consuming manual analysis towards automated methods developed from and benchmarked against the manual results. An automated method for detecting cutoff lows has been developed over a number of years, and is documented in a paper describing the model simulation of cutoff lows (Grose et al. 2012). There are a number of different methods for automatically detecting frontal systems, and these have been compared to the manual method in south western Australia (Hope et al. 2013). While the automated methods compare quite well with the manual analysis, there is room for improvement.

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2. Science reports describing the major drivers of rainfall variability in the grain regions and the manner in which they connect to rainfall.

The large-scale remote drivers of climate variability in Australia were studied by Risbey et al. (2009). They noted the importance of tropical drivers (ENSO and the IOD) and atmospheric blocking as remote drivers of rainfall variability in the grain-growing season (Apr-Oct) in southern Australia. Recent trends in rainfall in this region were examined and found to be substantially related to cutoff low weather systems and the associated blocking (Risbey et al. 2012). The teleconnection pathways between tropical drivers (ENSO and the IOD) and Australian rainfall were examined by Cai et al. (2011), and they postulated the importance of atmospheric Rossby waves in connecting tropical ocean temperature anomalies with southern Australian rainfall. In particular they highlighted the importance of the Indian Ocean as a source of Rossby waves. Ummenhofer et al. (2011) further emphasised the importance of the Indian Ocean in low-frequency variability and multi-year droughts. A concept map of the major drivers and processes was produced by McIntosh (2011). This project concluded that the most important drivers to study in connection with southern Australian rainfall were those which generated atmospheric Rossby waves, primarily from the Indian Ocean, and atmospheric blocking. This is not to say that other drivers are unimportant, but Rossby waves and atmospheric blocking would appear to have the greatest influence on rainfall in the grain-growing regions. Pook et al. (2013b) have studied the seasonal cycle of blocking in the Australian region, possible factors controlling blocking, and the relationship to rainfall via synoptic weather systems. This study confirms the association between atmospheric blocking and rainfall through the mechanism of cutoff low synoptic systems in all seasons except summer. It is also shown that blocking has no significant correlation with rainfall due to fronts. Furthermore, the meridional temperature gradient in the Australian region, particularly the land-southern ocean temperature contrast, is shown to be an important controlling factor in blocking. Tropical ocean temperature anomalies are known to drive anomalous atmospheric convection that generates atmospheric Rossby waves. These waves propagate into mid-latitudes and influence weather systems there. The propagation pathways are such that Indian Ocean temperature anomalies affect weather systems in southern Australia. Careful analysis of observations suggests that this mechanism might not be as simple as the analysis of (Cai et al. 2011) indicated. There is a barrier to Rossby wave propagation just south of Australia associated with the southern flank of the sub-tropical jet. Rossby waves cannot easily propagate into the Great Australian Bight to influence weather systems there. Instead, Rossby waves appear to “break”, that is, convert energy into transient eddies that then feed back onto the mean flow to generate height anomalies that in turn alter the weather systems. This new understanding is important because it provides a relatively sensitive and dynamically-based test of seasonal climate forecast models. If climate models cannot accurately simulate the Rossby wave barrier, then the tropical influence on mid-latitude weather systems is likely to be inaccurate. This work has been presented at a number of scientific seminars, and a manuscript is in preparation.

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3. Science reports evaluating model performance of remote drivers and teleconnections.

There are a number of key features that climate models must simulate in order to have good prospects of forecasting rainfall in southern Australia: cutoff lows, atmospheric blocking and the Rossby wave teleconnection pathway from the Indian Ocean including the Rossby wave barrier. This is in addition to more conventional diagnostics such as the simulation of ENSO, the IOD, SAM and the correlations to rainfall. Risbey et al. (2011) have evaluated the ability of the ACCESS atmospheric model to simulate teleconnections to Australian rainfall when forced by observed sea-surface temperatures. The ENSO teleconnection was present in spring but not winter, the IOD teleconnection was only weak, the SAM teleconnection was hampered by the model’s inability to represent small-scale topography, and the blocking teleconnection was quite good. The next step is to evaluate key processes in a coupled ocean-atmosphere model where feedback mechanisms may alter behaviour relative to an atmosphere-only model. POAM has a good representation of ENSO, but has difficulty getting good skill at predicting the IOD. Grose et al. (2012) examine the ability of a coupled ocean-atmosphere climate model to simulate cutoff lows in southeast Australia. They find that the model under-predicts the occurrence of cutoff lows by 47%, consistent with other studies using coarse-grid models. However, when a higher resolution model is used, this under-prediction reduces to about 30%. These results are mirrored in the ability of the models to represent the split jet and associated atmospheric blocking. The conclusions are: that climate models have difficulty representing one of the key rainfall mechanisms for southern Australia, that model resolution is only a partial solution to this problem, and that understanding and improving the representation of atmospheric blocking in climate models is of utmost importance. Factors controlling blocking in a coupled climate model have been explored by Ummenhofer et al. (2013). They find that meridional temperature gradients associated with the land-sea temperature contrast have a significant effect on blocking. In particular, warm ocean temperatures north of Australia can increase blocking through two mechanisms: changing the thermal wind which alters the zonal flow, and the generation of Rossby waves which propagate into mid-latitudes and affect blocking. A comparison of the propagation of Rossby waves in observations and the POAMA seasonal climate model has been made by McIntosh and Hendon (2013) and in attachment 4 (Rossby Waves). They find that POAMA has a much smaller barrier to Rossby waves propagating south-eastwards from the tropics than is seen in the observations. However, this does not lead to an excess of Rossby wave energy reaching and interacting with the weather systems south of Australia. The flux of Rossby wave energy coming out of the Indian Ocean is much reduced in POAMA compared to observations, so that the much-reduced “no-go zone” in POAMA is not itself a problem. It is not known what would happen if POAMA did generate enough Rossby wave energy in the Indian Ocean. One possibility is that this energy would interfere unrealistically with weather systems influencing southern Australia. The other possibility is that these increased Rossby waves would actually set up their own barrier by wave-breaking processes. In any event, it is clear that tropical Indian Ocean processes in POAMA, probably related to convection and clouds, need further study to improve their representation and generation of Rossby waves.

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Output

Publications

Brown, J.N., A. Sen Gupta, J.R. Brown, L. Muir, J. Risbey, X. Zhang, A. Ganachaud, B. Murphy, and S. Wijffels 2012: Implications of CMIP3 model biases and uncertainties for climate projections in the western tropical Pacific. Clim. Change, DOI 10.1007/s10584-012-0603-5.

Grose, M., M. Pook, P. McIntosh, J. Risbey, and N. Bindoff 2012: The simulation of cutoff lows in a

regional climate model: reliability and future trends. Climate Dynamics, 39, 445-459. Hope, P., K. Keay, M. Pook, J. Catto, I. Simmonds, G. Mills, P. McIntosh, J. Risbey, and G. Berry 2013:

Objective methods of frontal recognition for climate studies: a case study in south western Australia. Revised version submitted to Mon. Wea. Rev.

McIntosh, P.C., J.S. Risbey, J.N. Brown and M.J. Pook, 2012: Apparent and real sources of rainfall

associated with a cutoff low in southeast Australia. CAWCR Research Letters, 8, 4-9. McIntosh, P.C. and H.H. Hendon, 2013: Rossby wave teleconnections to Australian weather in

observations and models. 19th National Australian Meteorological and Oceanographic Society Conference, Melbourne, Australia.

McIntosh, P.C., 2013: Seasonal climate forecasts: reading tea-leaves in a digital age. The

Conversation, viewed 6 May 2013, <https://theconversation.com/seasonal-climate-forecasts-reading-tea-leaves-in-a-digital-age-12801>

Mitchell, R. 2012: Weather forecasting: it's complex. CLIMAG, 22, 6-7. Mitchell, R. 2013: WA farmers battle complex seasonal variability. CLIMAG, 24, 6. O'Kane, T., J. Risbey, C. Franzke, I. Horenko, and D. Monselesan 2012: Changes in the meta-stability

of the mid-latitude Southern Hemisphere circulation and the utility of non-stationary cluster analysis and split flow blocking indices as diagnostic tools. J. Atmos. Sci. (accepted for publication).

O'Kane, T., R. Matear, M. Chamberlain, J. Risbey, B. Sloyan, and I. Horenko 2013: Nonlinear intrinsic

and forced modes of low frequency variability in simulated southern ocean and sea ice dynamics. Ocean Modelling (submitted).

Pook, M., J. Risbey, and P. McIntosh 2012: The Synoptic Climatology of Cool-Season Rainfall in the

Central Wheatbelt of Western Australia. Mon. Wea. Rev., 140, 28-43. Pook, M.J., J.S. Risbey and P.C. McIntosh, 2013: A comparative synoptic climatology of daily rainfall in

major grain-growing regions of southern Australia. Theoretical and Applied Climatology (submitted).

Pook, M.J., J.S. Risbey, P.C. McIntosh, C.C. Ummenhofer, A.G. Marshall and G.A. Meyers, 2013: The

seasonal cycle of blocking in the Australian region and its relationship to rainfall. Mon. Wea. Rev. (submitted).

Risbey, J., P. McIntosh, M. Pook, H. Rashid, and T. Hirst 2011: Evaluation of rainfall drivers and

teleconnections in an ACCESS AMIP run. Aust. Meteorol. Oceanographic J., 61, 91-105.

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Risbey, J., P. McIntosh, and M. Pook 2012: Synoptic components of rainfall variability and trends in southeast Australia. Int. J. Climatol., DOI: 10.1002/joc.3597

Risbey, J., M. Pook, and P. McIntosh 2013: Spatial trends in synoptic rainfall in southern Australia.

Geophys. Res. Lett. (submitted). Ummenhofer, C., A. Sen Gupta, P. Briggs, M. England, P. McIntosh, G. Meyers, M. Pook, M. Raupach,

and J. Risbey 2011: Indian and Pacific Ocean influences on Southeast Australian drought and soil moisture. J. Climate, 24, 1313-1326.

Ummenhofer, C.C., P.C. McIntosh, M.J. Pook and J.S. Risbey, 2013: Impact of surface forcing on

southern hemisphere atmospheric blocking in the Australia-New Zealand sector. J. Climate (accepted for publication).

Presentations and Media

"A little bit of everything: past, present and future", Peter McIntosh, 180 audience, Birchip Grains Expo, 1 July 2010, growers, industry. "Rain bearing weather systems in SE Australia: Do models rain for the right reasons?", Peter McIntosh, 15 audience, ACE CRC Climate Futures Session, 20th August 2010, researchers. "Synoptic Systems - an overview and synthesis", Pandora Hope, 140 audience, Melbourne 28 April 2011, researchers, CMIP5 (Coupled Model Intercomparison Experiment #5) workshop. "Climate Variability", Peter McIntosh, 15 audience, Climate Champions program, Melbourne, 5 July 2010, growers. "Climate change", James Risbey, 15 audience, Climate Champions Program, Melbourne, 5 July 2010, growers. "Rainfall teleconnections to Tasmania", James Risbey, 15 audience, ACE CRC Climate Futures Session, 20th August 2010, researchers. "Rainfall teleconnections in an ACCESS AMIP run", James Risbey, 60 audience, AMOS Extreme Weather conference, Wellington, February 2011, researchers. "The seasonal cycle of blocking and rainfall variability in Australia", Mike Pook, 60 audience, AMOS Extreme Weather conference, Wellington, February 2011, researchers. "Last year, this year, and a bit of research", Peter McIntosh, 150 audience, Birchip Grains Expo, 7 July 2011, growers, industry. "Teleconnections", Peter McIntosh, 25 audience, MCV Forum, 11 Oct 2011, researchers. "Climate forecasting: It's role in agronomic management", Peter McIntosh, 40 audience, CSIRO Sustainable Agriculture Flagship workshop, 2-3 June 2011, researchers. "Seasonal forecast and climate models", Peter McIntosh. Birchip Climate Workshop, "Weathering the Future". Birchip, 22 March 2012. Growers, industry, researchers, total 67 audience.

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Radio interview: Radio National's Bush Telegraph John Ferrier, Peter Hayman, Peter McIntosh with Michael Mackenzie Melbourne, 14 November 2012. "Seasonal forecasting: challenges and benefits", Peter McIntosh. BCG Agribusiness Forum Melbourne Town Hall, 14 November 2012. Growers, industry, researchers, stakeholders, total ~120 audience. "A Rossby wave teleconnection conundrum", Peter McIntosh. Centre of Excellence for Climate System Science, 25-27 September 2012, Hobart. Researchers, ~60 audience. "Value and payoff time of POAMA seasonal forecasts: lessons from a case study" Peter McIntosh, GRDC Water Use Efficiency annual meeting, 7-8 August, Hobart. Researchers, ~50 audience. "Climate, weather and agriculture", Peter McIntosh, Lockington Landcare group, Lockington, 30 August 2012, Farmers, 5 audience. Part talk and contribution to workshop, Peter McIntosh MCV workshop, Canberra, 22 August 2012 Researchers, farmers, RDC executives, stakeholders, 35 audience. Talk 1: "POAMA for WA farming", Peter McIntosh Talk 2: "Teleconnections and POAMA", Peter McIntosh Talk 3: "POAMA experimental web site from a user's perspective", Peter McIntosh and Susan Carn. POAMA workshop, Melbourne, 29-30 November 2012. Farmers, researchers, RDC executives, stakeholders, ~50 audience. "Impact of surface forcing for southern hemisphere atmospheric blocking" Caroline Ummenhofer et al., 10th International Conference on Southern Hemisphere Meteorology and Oceanography. 23-27 April 2012, New Caledonia. Pook, M.J., J.S. Risbey and P.C. McIntosh “The synoptic decomposition of cool season rainfall in southern Australian cropping regions." Target Audience: 200 CMAR and CAWCR scientists at CMAR Science Symposium, 20 March 2012. Pook, M.J., J.S. Risbey and P.C. McIntosh “Key synoptic components of cool season rainfall across southern Australia”. Target Audience: Australian and international meteorologists/climatologists at the 10th International Conference on Southern Hemisphere Meteorology and Climatology, 20 April 2012. Pook, M.J., J.S. Risbey and P.C. McIntosh “Key synoptic components of cool season rainfall across southern Australia”. Target Audience: Agronomists and farmers at the GRDC National Water Use Efficiency Meeting, Hobart, 7 August 2012. Pook, M.J., J.S. Risbey, C.C. Ummenhofer, P. Briggs and T. Cohen. “A synoptic climatology of heavy rain events in the Lake Eyre and lake Frome catchments.” ”. Target Audience: Australian and international meteorologists/climatologists at the AMOS 2013 Conference, February 2013. McIntosh, P.C. and H.H. Hendon: Rossby wave teleconnections to Australian weather in observations and models. Target Audience: Australian and international meteorologists/climatologists at the AMOS 2013 Conference, February 2013, ~100 audience. Article in Hobart Mercury 19 June 2013: “New focus to unlock weather secrets” interviewing Mike Pook regarding drivers of cutoff lows in south-east Australia.

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Acknowledgements

Funding for this project was provided by the Managing Climate Variability Program and the CSIRO Climate Adaptation Flagship.

List of attachments included with hardcopy

1. Grose, M., M. Pook, P. McIntosh, J. Risbey, and N. Bindoff 2012: The simulation of cutoff lows in a regional climate model: reliability and future trends. Climate Dynamics, 39, 445-459.

2. McIntosh, P.C. and H.H. Hendon: Rossby wave teleconnections to Australian weather in observations and models. Abstract, AMOS 2013 Conference, February 2013.

3. McIntosh, P.C. and H.H. Hendon: Teleconnections and POAMA. Talk, AMOS 2013 Conference, February 2013.

4. McIntosh, P.C. and H.H. Hendon, 2013: Rossby Wave Trains Forced by Convection Variations over the Tropical Indian Ocean: Observations and POAMA.

5. Pook, M., J. Risbey, and P. McIntosh 2012: The Synoptic Climatology of Cool-Season Rainfall in the Central Wheatbelt of Western Australia. Mon. Wea. Rev., 140, 28-43.

6. Pook, M.J., J.S. Risbey and P.C. McIntosh, 2013: A comparative synoptic climatology of daily rainfall in major grain-growing regions of southern Australia. Theoretical and Applied Climatology (submitted).

7. Pook, M.J., J.S. Risbey, P.C. McIntosh, C.C. Ummenhofer, A.G. Marshall and G.A. Meyers, 2013: The seasonal cycle of blocking in the Australian region and its relationship to rainfall. Mon. Wea. Rev.(accepted for publication).

8. Risbey, J., P. McIntosh, M. Pook, H. Rashid, and T. Hirst 2011: Evaluation of rainfall drivers and teleconnections in an ACCESS AMIP run. Aust. Meteorol. Oceanographic J., 61, 91-105.

9. Risbey, J., P. McIntosh, and M. Pook 2012: Synoptic components of rainfall variability and trends in southeast Australia. Int. J. Climatol., DOI: 10.1002/joc.3597

10. Risbey, J., M. Pook, and P. McIntosh 2013: Spatial trends in synoptic rainfall in southern Australia. Geophys. Res. Lett. (accepted for publication).

11. Ummenhofer, C.C., P.C. McIntosh, M.J. Pook and J.S. Risbey, 2013: Impact of surface forcing on southern hemisphere atmospheric blocking in the Australia-New Zealand sector. J. Climate (accepted for publication).

References

Cai, W., P. van Rensch, T. Cowan, and H. H. Hendon, 2011: Teleconnection Pathways of ENSO and the IOD and the Mechanisms for Impacts on Australian Rainfall. Journal of Climate, 24, 3910-3923.

Grose, M. R., M. J. Pook, P. C. McIntosh, J. S. Risbey, and N. L. Bindoff, 2012: The simulation of cutoff lows in a regional climate model: reliability and future trends. Climate Dynamics, 39, 445-459.

Hope, P., and Coauthors, 2013: Objective methods of frontal recognition for climate studies: a case study in south western Australia. Monthly Weather Review, (Submitted).

McIntosh, P. C., cited 2013: Southern Australian Rainfall – Teleconnections Concept Map. [Available online at http://www.marine.csiro.au/~mcintosh/Teleconnections/Teleconnections.html.]

McIntosh, P. C., and H. H. Hendon, 2013: Rossby wave teleconnections to Australian weather in observations and models. 19th National Australian Meteorological and Oceanographic Society Conference, AMOS.

Pook, M., J. Risbey, and P. McIntosh, 2010: East coast lows, atmospheric blocking and rainfall: A Tasmanian perspective. IOP Conference Series: Earth and Environmental Science, 11, 012011-012011.

Pook, M. J., P. C. McIntosh, and G. A. Meyers, 2006: The Synoptic Decomposition of Cool-Season Rainfall in the Southeastern Australian Cropping Region. Journal of Applied Meteorology and Climatology, 45, 1156-1156-1170.

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Pook, M. J., J. S. Risbey, and P. C. McIntosh, 2012: The Synoptic Climatology of Cool-Season Rainfall in the Central Wheatbelt of Western Australia. Monthly Weather Review, 140, 28-43.

——, 2013a: A comparative synoptic climatology of cool-season rainfall in major grain-growing regions of southern Australiac. Theoretical and Applied Climatology, (Submitted).

Pook, M. J., J. S. Risbey, P. C. McIntosh, C. C. Ummenhofer, A. G. Marshall, and G. A. Meyers, 2013b: The seasonal cycle of blocking in the Australian region and its relationship with rainfall. Monthly Weather Review, (accepted for publication).

Risbey, J. S., P. C. McIntosh, and M. J. Pook, 2012: Synoptic components of rainfall variability and trends in southeast Australia. International Journal of Climatology.

Risbey, J. S., M. J. Pook, P. C. McIntosh, M. C. Wheeler, and H. H. Hendon, 2009: On the Remote Drivers of Rainfall Variability in Australia. Monthly Weather Review, 137, 3233-3253.

Risbey, J. S., P. C. McIntosh, M. J. Pook, H. A. Rashid, and A. C. Hirst, 2011: Evaluation of rainfall drivers and teleconnections in an ACCESS AMIP run. Australian Meteorological and Oceanographic Journal, 61, 91-105.

Ummenhofer, C. C., A. S. Gupta, M. J. Pook, and M. H. England, 2008: Anomalous Rainfall over Southwest Western Australia Forced by Indian Ocean Sea Surface Temperatures. Journal of Climate, 21, 5113-5134.

Ummenhofer, C. C., P. C. McIntosh, M. J. Pook, and J. S. Risbey, 2013: Impact of surface forcing on Southern Hemisphere atmospheric blocking in the Australia-New Zealand sector. Journal of Climate, (Accepted for publication).

Ummenhofer, C. C., and Coauthors, 2011: Indian and Pacific Ocean Influences on Southeast Australian Drought and Soil Moisture. Journal of Climate, 24, 1313-1336.