Jennifer Catto

Atmospheric fronts in current and future climates

Publisher: American Geophysical Union (AGU)

Date: 10-11-2014

DOI: 10.1002/2014GL061943

A comparison of automated methods of front recognition for climate studies: A case study in southwest Western Australia

Publisher: American Meteorological Society

Date: 2014

DOI: 10.1175/MWR-D-12-00252.1

Abstract: The identification of extratropical fronts in reanalyses and climate models is an important climate diagnostic that aids dynamical understanding and model verification. This study compares six frontal identification methods that are applied to June and July reanalysis data over the Central Wheatbelt of southwest Western Australia for 1979–2006. Much of the winter rainfall over this region originates from frontal systems. Five of the methods use automated algorithms. These make use of different approaches, based on shifts in 850-hPa winds (WND), gradients of temperature (TGR) and wet-bulb potential temperature (WPT), pattern matching (PMM), and a self-organizing map (SOM). The sixth method was a manual synoptic technique (MAN). On average, about 50% of rain days were associated with fronts in most schemes (although methods PMM and SOM exhibited a lower percentage). On a daily basis, most methods identify the same systems more than 50% of the time, and over the 28-yr period the seasonal time series correlate strongly. The association with rainfall is less clear. The WND time series of seasonal frontal counts correlate significantly with Central Wheatbelt rainfall. All automated methods identify fronts on some days that are classified as cutoff lows in the manual analysis, which will impact rainfall correlations. The front numbers identified on all days by the automated methods decline from 1979 to 2006 (but only the TGR and WPT trends were significant at the 10% level). The results here highlight that automated techniques have value in understanding frontal behavior and can be used to identify the changes in the frequency of frontal systems through time.

Correction to: The contributions of fronts, lows and thunderstorms to southern Australian rainfall

Publisher: Springer Science and Business Media LLC

Date: 28-08-2021

DOI: 10.1007/S00382-020-05421-0

The relationship between clouds and dynamics in Southern Hemisphere extratropical cyclones in the real world and a climate model

Publisher: American Geophysical Union (AGU)

Date: 13-06-2014

DOI: 10.1002/2013JD020699

The intensity and motion of hybrid cyclones in the Australian region in a composite potential vorticity framework

Publisher: Wiley

Date: 2019

DOI: 10.1002/QJ.3430

Synoptic climatology of hybrid cyclones in the Australian region

Publisher: Wiley

Date: 2019

DOI: 10.1002/QJ.3431

The contributions of fronts, lows and thunderstorms to southern Australian rainfall

Publisher: Springer Science and Business Media LLC

Date: 17-06-2020

DOI: 10.1007/S00382-020-05338-8

Abstract: A systematic analysis of the main weather types influencing southern Australian rainfall is presented for the period 1979–2015. This incorporates two multi-method datasets of cold fronts and low pressure systems, which indicate the more robust fronts and lows as distinguished from the weaker and less impactful events that are often indicated only by a single method. The front and low pressure system datasets are then combined with a dataset of environmental conditions associated with thunderstorms, as well as datasets of warm fronts and high pressure systems. The results demonstrate that these weather types collectively account for about 86% of days and more than 98% of rainfall in Australia south of 25° S. We also show how the key rain-bearing weather systems vary throughout the year and for different regions, with the co-occurrence of simultaneous lows, fronts and thunderstorm conditions particularly important during the spring and summer months in southeast Australia.

North Australian Sea Surface Temperatures and the El Niño–Southern Oscillation in the CMIP5 Models

Publisher: American Meteorological Society

Date: 18-07-2012

DOI: 10.1175/JCLI-D-12-00214.1

Abstract: Aspects of the climate of Australia are linked to interannual variability of the sea surface temperatures (SSTs) to the north of the country. SST anomalies in this region have been shown to exhibit strong, seasonally varying links to ENSO and tropical Pacific SSTs. Previously, the models participating in phase 3 of the Coupled Model Intercomparison Project (CMIP3) have been evaluated and found to vary in their abilities to represent both the seasonal cycle of correlations between the Niño-3.4 and north Australian SSTs and the evolution of SSTs during composite El Niño and La Niña events. In this study, the new suite of models participating in the CMIP5 is evaluated using the same method. In the multimodel mean, the representation of the links is slightly improved, but generally the models do not capture the strength of the negative correlations during the second half of the year. The models also still struggle to capture the SST evolution in the north Australian region during El Niño and La Niña events.

Relating global precipitation to atmospheric fronts

Publisher: American Geophysical Union (AGU)

Date: 18-05-2012

DOI: 10.1029/2012GL051736

Can the CMIP5 models represent winter frontal precipitation?

Publisher: American Geophysical Union (AGU)

Date: 24-10-2015

DOI: 10.1002/2015GL066015

The influence of changes in synoptic regimes on north Australian wet season rainfall trends

Publisher: American Geophysical Union (AGU)

Date: 16-05-2012

DOI: 10.1029/2012JD017472

North Australian Sea Surface Temperatures and the El Niño–Southern Oscillation in Observations and Models

Publisher: American Meteorological Society

Date: 15-07-2012

DOI: 10.1175/JCLI-D-11-00311.1

Abstract: Interannual variations in the sea surface temperature (SST) to the north of Australia are strongly linked to variations in Australian climate, including winter rainfall and tropical cyclone numbers. The north Australian SSTs are also closely linked to ENSO and tropical Pacific SSTs, with the relationship exhibiting a strong seasonal cycle. Credible predictions of Australian climate change therefore depend on climate models being able to represent ENSO and its connection to north Australian SSTs, the topic of this study. First, the observational datasets of the Met Office Hadley Centre Sea Ice and Sea Surface Temperature (HadISST) and the NOAA Extended Reconstructed Sea Surface Temperature (ERSST) are used to document the links between the Niño-3.4 index and a north Australian SST index, and the temporal evolution of north Australian SSTs during ENSO events. During austral autumn, the correlation between Niño-3.4 SST and north Australian SST is positive, while in austral spring it is strongly negative. During El Niño events, the north Australian SST anomalies become negative in the austral spring preceding the development of the positive Niño-3.4 SST anomalies. The coupled models participating in the Coupled Model Intercomparison Project phase 3 (CMIP3) are evaluated in terms of this temporal evolution of Niño-3.4 SST and the relationship to north Australian SST for the twentieth-century simulations. Some of the models perform very well, while some do not capture the seasonal cycle of correlations at all. The way in which these relationships may change in the future is examined using the A2 emissions scenario in those models that do a reasonable job of capturing the present-day observed relationship, and very little change is found.

Compounding Heatwave‐Extreme Rainfall Events Driven by Fronts, High Moisture, and Atmospheric Instability

Publisher: American Geophysical Union (AGU)

Date: 28-10-2023

DOI: 10.1029/2023JD038761

Global relationship between fronts and warm conveyor belts and the impact on extreme precipitation

Publisher: American Meteorological Society

Date: 30-10-2015

DOI: 10.1175/JCLI-D-15-0171.1

Abstract: Extratropical cyclones are responsible for many extreme precipitation events in the midlatitudes. Warm conveyor belts (WCBs) and fronts are known to be related to the uplift and hence the precipitation within cyclones. The authors have investigated the link between WCBs and fronts and how such a link impacts the occurrence of extreme precipitation events. WCB trajectories have been calculated from the ERA-Interim dataset, and low-level (below 790 hPa) and midlevel (790–600 hPa) WCBs have been considered. These have been matched with objectively identified fronts (i.e., characterized by an overlap of WCB and front somewhere along the front). About 10% of cold fronts, 8% of warm fronts (identified using a thermal criterion), and 15% of wind fronts (identified using a wind shift method) are matched with WCBs, while up to 70% of WCBs are matched with fronts. Some WCBs, especially in the Southern Hemisphere, are not matched with either type of front (up to 70% east of Australia). The relationship between WCBs and fronts does not change much between the low levels and midlevels, indicating that the WCBs are already strongly associated with fronts during the lowest part of their ascent, although in the Southern Hemisphere the WCBs are more often related to warm fronts during their midtropospheric ascent. In parts of the midlatitudes, more than 60% of extreme precipitation events match either cold or warm fronts, and up to 90% of these have matched WCBs. Fronts associated with WCBs are found to be between 2 and 10 times more likely to produce extreme precipitation events than fronts without associated WCBs.

Discovery Early Career Researcher Award - Grant ID: DE140101305

Start Date: 2014

End Date: 06-2017

Amount: $394,921.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE150100089

Start Date: 2015

End Date: 12-2015

Amount: $490,000.00

Funder: Australian Research Council