Publication Date:
2023-08-31
Description:
Dry cold fronts, with large temperature differences across them, are a feature of the Australian summertime climate, with an apparent connection between strong dry cold fronts and increased fire danger in south-eastern Australia. While objective front detection methods exist, these methods are only applicable to gridded data, and require changing smoothing and threshold parameters as spatial resolution changes in order to obtain well-behaved results. This prevents use of these methods to analyse historic point records (such as station data), and to compare frontal behaviour in datasets of differing resolution. We present a method using daily temperature differences as way of identifying strong, dry cold fronts across both point records and variable resolution gridded data. This method is applied to station data, ERA5 reanalysis and CMIP6 model runs in order to determine the trend and variability in extreme dry fronts over south-east Australia. Station data and reanalysis agree on the frequency of strong cold fronts across different regions of Australia, but the longer station data records suggest that some trends seen in the reanalysis are a result of a shorter period of data. The CMIP6 models generally underestimate the number of extreme fronts seen near the surface compared to reanalysis, but display a roughly comparable level of interannual variability. In the station and reanalysis data, an apparent connection between the frequency of extreme fronts and the phase of climate patterns is seen, particularly for ENSO, which seems to be linked to soil moisture in inland southern Australia.
Language:
English
Type:
info:eu-repo/semantics/conferenceObject
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