The Synoptic Climatology of Cool-Season Rainfall in the Central Wheatbelt of Western Australia

Pook, Michael J.; Risbey, James S.; McIntosh, Peter C.

doi:10.1175/mwr-d-11-00048.1

Cited by 50 publications

(40 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Several other studies report similar cool-season declines across SEA and south-western Australia (e.g. Chubb et al 2011;Pook et al 2012), however the time period in many of these studies coincided with the end of the Millennium Drought. Consideration of the cool-season as a whole can mask…”

Section: Accepted Manuscriptmentioning

confidence: 73%

Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958–2012

Theobald

McGowan

Speirs

2016

Atmospheric Research

View full text Add to dashboard Cite

The hydroclimate of the Snowy Mountains, south-east Australia (SEA), is influenced by tropical and extra-tropical synoptic scale weather systems. Accordingly, it is sensitive to any changes in the mid-latitude westerly wind belt, the dominant driver of precipitation in winter, and the entrainment of moisture from tropical latitudes, particularly during the warmer months of the austral summer.The region has historically observed a cool-season (April -October) dominated precipitation regime. However, evidence is presented of a decline in precipitation during the autumn and spring transition months. Autumn precipitation is particularly important for crop sowing and agricultural production in the Murray-Darling Basin downstream of the Snowy Mountains, while spring precipitation influences snowmelt and water storage replenishment in the Snowy Mountains. Instead, we show a change in the annual precipitation distribution is evident, with an increase in precipitation during warmer months.Trend analyses for the period 1958 -2012 show a decrease in annual frequency of precipitation days capable of generating inflows to the catchments of the Snowy Mountains of -1.4 days per decade on average, whilst the precipitation they generate has increased by +5.7 mm per decade. These results align with climate change projections that precipitation events are becoming less frequent but more intense.

show abstract

Section: Accepted Manuscriptmentioning

confidence: 73%

Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958–2012

Theobald

McGowan

Speirs

2016

Atmospheric Research

View full text Add to dashboard Cite

show abstract

“…In the spring and summer, the belt is positioned to the south of SWWA and advects hot continental air to the coast while channeling the passage of rain-bearing frontal systems to the south, resulting in dry conditions. Summer rainfall is a result of surface convection, cutoff lows (Pook et al 2012), and northwesterly cloud bands that bring rain to the interior (Tapp and Barrell 1984). Infrequent, large-scale summer rain events in the SWWA, which occur only two or three times in a decade, were described by Wright (1974).…”

Section: A Southwest Western Australiamentioning

confidence: 99%

Multidecadal Evaluation of WRF Downscaling Capabilities over Western Australia in Simulating Rainfall and Temperature Extremes

Andrys

Lyons

Kala

2015

Journal of Applied Meteorology and Climatology

View full text Add to dashboard Cite

The authors evaluate a 30-yr (1981-2010) Weather Research and Forecast (WRF) Model regional climate simulation over the southwest of Western Australia (SWWA), a region with a Mediterranean climate, using ERA-Interim boundary conditions. The analysis assesses the spatial and temporal characteristics of climate extremes, using a selection of climate indices, with an emphasis on metrics that are relevant for forestry and agricultural applications. Two nested domains at 10-and 5-km resolution are examined, with the higherresolution simulation resolving convection explicitly. Simulation results are compared with a high-resolution, gridded observational dataset that provides daily rainfall, minimum temperatures, and maximum temperatures. Results show that, at both resolutions, the model is able to simulate the daily, seasonal, and annual variation of temperature and precipitation well, including extreme events. The higher-resolution domain displayed significant performance gains in simulating dry-season convective precipitation, rainfall around complex terrain, and the spatial distribution of frost conditions. The high-resolution domain was, however, influenced by grid-edge effects in the southwestern margin, which reduced the ability of the domain to represent frontal rainfall along the coastal region. On the basis of these results, the authors feel confident in using the WRF Model for regional climate simulations for the SWWA, including studies that focus on the spatial and temporal representation of climate extremes. This study provides a baseline climatological description at a high resolution that can be used for impact studies and will also provide a benchmark for climate simulations driven by general circulation models.

show abstract

“…The primary classification of synoptic systems followed Pook et al (2006Pook et al ( , 2012Pook et al ( , 2014 who specified three main categories: cold frontal systems associated with Southern Ocean depressions; cold-cored lows that have become separated from the westerly flow (cutoff lows); and a broad category labeled "other synoptic systems" that included, inter alia, troughs in the surface easterlies (easterly troughs) and cold troughs in the middle troposphere where a closed circulation was not present at 500 hPa. In this study the upper trough was required to contain a region of negative anomaly of 1000-500 hPa thickness of at least 20 geopotential meters.…”

Section: Methodsmentioning

confidence: 99%

“…The NCEP data consist of 4 analyses per day (at 6-hourly intervals from 0000 UTC) at a resolution of 2.5 • latitude by 2.5 • longitude for the standard atmospheric levels from the surface to the lower stratosphere. The reanalysis data are available from January 1948 although the Australian data have been used with caution prior to 1956 as the upper air data network was quite sparse prior to that time (Pook et al, 2012). The key fields sampled in the analysis were mean sea level pressure (MSLP), the 500 hPa geopotential height, the (computed) 1000-500 hPa atmospheric thickness and the 250 hPa wind.…”

Section: Datamentioning

confidence: 99%

“…The results of this analysis may then offer some insights into the characteristics of the enhanced rainfall periods in the geological record. Hence, in this paper we investigate the types of synoptic systems responsible for a selection of recent historical heavy rainfall events over the catchments of Lake Eyre and Lake Frome using accepted methods of synoptic climatology (e.g., Pook et al, 2006Pook et al, , 2012Pook et al, , 2014. We compare and contrast the dominant systems affecting the Lake Eyre catchment with those contributing to major events in the Lake Frome catchment.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A synoptic climatology of heavy rain events in the Lake Eyre and Lake Frome catchments

Pook

Risbey

Ummenhofer

et al. 2014

Front. Environ. Sci.

Self Cite

View full text Add to dashboard Cite

The rare occasions when Lake Eyre in central, southern Australia fills with water excite great interest and produce major ecological responses. The filling of other smaller lakes such as Lake Frome have less impact but can contribute important information about the current and past climates of these arid regions. Here, the dominant synoptic systems responsible for heavy rainfall over the catchments of Lake Eyre and Lake Frome since 1950 are identified and compared. Heavy rain events are defined as those where the mean catchment rainfall for 24 h reaches a prescribed threshold. There were 25 such daily events at Lake Eyre and 28 in the Lake Frome catchment. The combination of a monsoon trough at mean sea level and a geopotential trough in the mid-troposphere was found to be the synoptic system responsible for the majority of the heavy rain events affecting Lake Eyre and one in five of the events at Lake Frome. Complex fronts where subtropical interactions occurred with Southern Ocean fronts also contributed over 20% of the heavy rainfall events in the Frome catchment. Surface troughs without upper air support were found to be associated with 10% or fewer of events in each catchment, indicating that mean sea level pressure analyses alone do not adequately capture the complexity of the heavy rainfall events. At least 80% of the heavy rain events across both catchments occurred when the Southern Oscillation Index (SOI) was in its positive phase, and for Lake Frome, the SOI exceeded +10 on 60% of occasions, suggesting that the background atmospheric state in the Pacific Ocean was tilted toward La Niña. Hydrological modeling of the catchments suggests that the 12-month running mean of the soil moisture in a sub-surface layer provides a low frequency filter of the precipitation and matches measured lake levels relatively well.

show abstract

The Synoptic Climatology of Cool-Season Rainfall in the Central Wheatbelt of Western Australia

Cited by 50 publications

References 36 publications

Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958–2012

Trends in synoptic circulation and precipitation in the Snowy Mountains region, Australia, in the period 1958–2012

Multidecadal Evaluation of WRF Downscaling Capabilities over Western Australia in Simulating Rainfall and Temperature Extremes

A synoptic climatology of heavy rain events in the Lake Eyre and Lake Frome catchments

Contact Info

Product

Resources

About