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Andrea Taschetto   Dr.  Other 
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Andrea Taschetto published an article in November 2017.
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Matthew England

108 shared publications

Climate Change Research Centre (CCRC), School of Mathematics and Statistics, The University of New South Wales, Sydney, NSW, 2052, Australia

Matthew H. England

55 shared publications

I. Wainer

47 shared publications

A. Sen Gupta

34 shared publications

Publication Record
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(2006 - 2017)
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CONFERENCE-ARTICLE 6 Reads 0 Citations <strong>The role of ocean variability for droughts and wet periods in South America</strong> Andrea Taschetto Published: 06 November 2017
First International Electronic Conference on the Hydrological Cycle, doi: 10.3390/CHyCle-2017-04844
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Interannual precipitation over South America is largely modulated by the large-scale modes of variability in the surrounding oceans. In particular, the El Niño – Southern Oscillation (ENSO) affects South American rainfall generating a dipole pattern of precipitation over the northern and southeastern regions. In this study the role of the oceans for South American rainfall variability is investigated using the National Centre for Atmospheric Research (NCAR) Community Earth System Model (CESM). Multi-century simulations are performed to estimate rainfall mean and variability in South America in a fully coupled climate system and in the absence of ocean variability. Results show that interannual and decadal rainfall variability over South America is primarily associated with sea surface temperature anomalies in the Indo-Pacific region and variations in the extent of the Pacific warm pool. In the absence of ocean variability, droughts tend to last longer, particularly over the northeastern region. Thus, ENSO acts as a restoring mechanism for rainfall deficits and surplus over the continent. Interestingly, ENSO events are not only crucial for modulating rainfall variability, but also for determining mean precipitation over South America.


Article 1 Read 0 Citations Can Australian Multiyear Droughts and Wet Spells Be Generated in the Absence of Oceanic Variability? Andrea S. Taschetto, Alex Sen Gupta, Caroline C. Ummenhofer,... Published: 01 September 2016
Journal of Climate, doi: 10.1175/jcli-d-15-0694.1
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Anomalous conditions in the tropical oceans, such as those related to El Niño–Southern Oscillation and the Indian Ocean dipole, have been previously blamed for extended droughts and wet periods in Australia. Yet the extent to which Australian wet and dry spells can be driven by internal atmospheric variability remains unclear. Natural variability experiments are examined to determine whether prolonged extreme wet and dry periods can arise from internal atmospheric and land variability alone. Results reveal that this is indeed the case; however, these dry and wet events are found to be less severe than in simulations incorporating coupled oceanic variability. Overall, ocean feedback processes increase the magnitude of Australian rainfall variability by about 30% and give rise to more spatially coherent rainfall impacts. Over mainland Australia, ocean interactions lead to more frequent extreme events, particularly during the rainy season. Over Tasmania, in contrast, ocean–atmosphere coupling increases mean rainfall throughout the year. While ocean variability makes Australian rainfall anomalies more severe, droughts and wet spells of duration longer than three years are equally likely to occur in both atmospheric- and ocean-driven simulations. Moreover, they are essentially indistinguishable from what one expects from a Gaussian white noise distribution. Internal atmosphere–land-driven megadroughts and megapluvials that last as long as ocean-driven events are also identified in the simulations. This suggests that oceanic variability may be less important than previously assumed for the long-term persistence of Australian rainfall anomalies. This poses a challenge to accurate prediction of long-term dry and wet spells for Australia.
Article 1 Read 6 Citations How sensitive are the Pacific–tropical North Atlantic teleconnections to the position and intensity of El Niño-related w... A. S. Taschetto, R. R. RODRIGUES, G. A. Meehl, S. McGregor, ... Published: 04 June 2015
Climate Dynamics, doi: 10.1007/s00382-015-2679-x
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Article 1 Read 3 Citations Evaluation of monsoon seasonality and the tropospheric biennial oscillation transitions in the CMIP models Nicolas C. Jourdain, Caroline C. Ummenhofer, Karumuri Ashok,... Published: 26 October 2012
Geophysical Research Letters, doi: 10.1029/2012gl053322
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[1] Characteristics of the Indian and Australian summer monsoon systems, their seasonality and interactions are examined in a variety of observational datasets and in the Coupled Model Intercomparison Project Phase 3 and 5 (CMIP3 and CMIP5) climate models. In particular, it is examined whether preferred monsoon transitions between the two regions and from one year to another, that form parts of the Tropospheric Biennial Oscillation, can lead to improved predictive skill. An overall improvement in simulation of seasonality for both monsoons is seen in CMIP5 over CMIP3, with most CMIP5 models correctly simulating very low rainfall rates outside of the monsoon season. The predictability resulting from each transition is quantified using a Monte Carlo technique. The transition from strong/weak Indian monsoon to strong/weak Australian monsoon shows ∼15% enhanced predictability in the observations, in estimating whether the following monsoon will be stronger/weaker than the climatology. Most models also successfully simulate this transition. However, enhanced predictability for other transitions is less clear.
Article 1 Read 9 Citations Can Indian Ocean SST anomalies influence South American rainfall? Andréa S. Taschetto, Tercio Ambrizzi Published: 20 August 2011
Climate Dynamics, doi: 10.1007/s00382-011-1165-3
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In this study we examine the impact of Indian Ocean sea surface temperature (SST) variability on South American circulation using observations and a suite of numerical experiments forced by a combination of Indian and Pacific SST anomalies. Previous studies have shown that the Indian Ocean Dipole (IOD) mode can affect climate over remote regions across the globe, including over South America. Here we show that such a link exists not only with the IOD, but also with the Indian Ocean basin-wide warming (IOBW). The IOBW, a response to El Niño events, tends to reinforce the South American anomalous circulation in March-to-May associated with the warm events in the Pacific. This leads to increased rainfall in the La Plata basin and decreased rainfall over the northern regions of the continent. In addition, the IOBW is suggested to be an important factor for modulating the persistence of dry conditions over northeastern South America during austral autumn. The link between the IOBW and South American climate occurs via alterations of the Walker circulation pattern and through a mid-latitude wave-train teleconnection.
Article 1 Read 9 Citations The influence of Southern Hemisphere sea-ice extent on the latitude of the mid-latitude jet stream J. Kidston, A. S. Taschetto, D. W. J. Thompson, M. H. Englan... Published: 01 August 2011
Geophysical Research Letters, doi: 10.1029/2011gl048056
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[1] An atmospheric general circulation model with prescribed sea‐ice and sea‐surface temperatures is used to examine the sensitivity of the atmospheric circulation to changes in sea‐ice extent in the Southern Hemisphere. Experiments are conducted where the sea‐ice edge is expanded or contracted by 7 degrees of latitude compared with its position in a control run. The experiments suggest that the latitude of the sea‐ice edge influences the latitude of the Southern Hemisphere mid‐latitude jet stream, but that the amplitude of the atmospheric response depends critically on the location and seasonality of the sea‐ice anomalies. During the cold season, the mid‐latitude jet shifts significantly poleward when the sea‐ice extent is increased, but exhibits very little response when the sea‐ice extent is decreased. During the warm season, the jet does not shift significantly regardless of whether the sea‐ice edge is extended or contracted. The cause of the asymmetry in the atmospheric response relates to the extent to which the sea‐ice anomalies affect meridional temperature gradients in the near‐surface baroclinic zone. The results suggest that 1) any future decreases in Antarctic sea‐ice are unlikely to have a profound effect on the Southern Hemisphere mid‐latitude circulation; and 2) the usefulness of sea‐ice variability for seasonal prediction is limited to the cold season and to the case of increases in sea‐ice extent.