ORCID Profile
0000-0001-7840-0467
Current Organisation
University of Tasmania
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Publisher: Wiley
Date: 13-12-2013
DOI: 10.1002/QJ.2247
Publisher: Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc.
Date: 03-12-2017
Publisher: Elsevier BV
Date: 05-2023
Publisher: MDPI AG
Date: 02-03-2021
DOI: 10.3390/FIRE4010010
Abstract: Lightning strikes are pervasive, however, their distributions vary both spatially and in time, resulting in a complex pattern of lightning-ignited wildfires. Over the last decades, lightning-ignited wildfires have become an increasing threat in south-east Australia. Lightning in combination with drought conditions preceding the fire season can increase probability of sustained ignitions. In this study, we investigate spatial and seasonal patterns in cloud-to-ground lightning strikes in the island state of Tasmania using data from the Global Position and Tracking System (GPATS) for the period January 2011 to June 2019. The annual number of lightning strikes and the ratio of negative to positive lightning (78:22 overall) were considerably different from one year to the next. There was an average of 80 lightning days per year, however, 50% of lightning strikes were concentrated over just four days. Most lightning strikes were observed in the west and north of the state consistent with topography and wind patterns. We searched the whole population of lightning strikes for those most likely to cause wildfires up to 72 h before fire detection and within 10 km of the ignition point derived from in situ fire ignition records. Only 70% of lightning ignitions were matched up with lightning records. The lightning ignition efficiency per stroke/flash was also estimated, showing an annual average efficiency of 0.24% ignition per lightning stroke with a seasonal maximum during summer. The lightning ignition efficiency as a function of different fuel types also highlighted the role of buttongrass moorland (0.39%) in wildfire incidents across Tasmania. Understanding lightning climatology provides vital information about lightning characteristics that influence the probability that an in idual stroke causes ignition over a particular landscape. This research provides fire agencies with valuable information to minimize the potential impacts of lightning-induced wildfires through early detection and effective response.
Publisher: Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc.
Date: 03-12-2017
Publisher: American Geophysical Union (AGU)
Date: 10-11-2014
DOI: 10.1002/2014JD022448
Publisher: Elsevier BV
Date: 02-2006
Publisher: American Meteorological Society
Date: 08-2018
Abstract: A data assimilation system (DAS) is described for global atmospheric reanalysis from 0- to 100-km altitude. We apply it to the 2014 austral winter of the Deep Propagating Gravity Wave Experiment (DEEPWAVE), an international field c aign focused on gravity wave dynamics from 0 to 100 km, where an absence of reanalysis above 60 km inhibits research. Four experiments were performed from April to September 2014 and assessed for reanalysis skill above 50 km. A four-dimensional variational (4DVAR) run specified initial background error covariances statically. A hybrid-4DVAR (HYBRID) run formed background error covariances from an 80-member forecast ensemble blended with a static estimate. Each configuration was run at low and high horizontal resolution. In addition to operational observations below 50 km, each experiment assimilated 105 observations of the mesosphere and lower thermosphere (MLT) every 6 h. While all MLT reanalyses show skill relative to independent wind and temperature measurements, HYBRID outperforms 4DVAR. MLT fields at 1-h resolution (6-h analysis and 1–5-h forecasts) outperform 6-h analysis alone due to a migrating semidiurnal (SW2) tide that dominates MLT dynamics and is temporally aliased in 6-h time series. MLT reanalyses reproduce observed SW2 winds and temperatures, including phase structures and 10–15-day litude vacillations. The 0–100-km reanalyses reveal quasi-stationary planetary waves splitting the stratopause jet in July over New Zealand, decaying from 50 to 80 km then reintensifying above 80 km, most likely via MLT forcing due to zonal asymmetries in stratospheric gravity wave filtering.
Publisher: American Geophysical Union (AGU)
Date: 08-11-2016
DOI: 10.1002/2016JD025627
Publisher: American Meteorological Society
Date: 07-2015
Abstract: Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations for GW momentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model’s land–sea differences in convective latent heating.
Publisher: American Geophysical Union (AGU)
Date: 28-08-2012
DOI: 10.1029/2012EO350001
Publisher: Wiley
Date: 18-07-2022
DOI: 10.1002/JOC.7791
Abstract: While extreme weather and climate events have been studied for several decades, analysis of compound events has only begun in recent years. In this burgeoning field there are still many open questions around the optimal methodology and analysis tools for analysis. After consultation with state emergency services in Tasmania, Australia, we examined which compound events have the largest impacts on their organizations. Through this consultation process we found that many of the severe flooding events in the state do not coincide with the highest rainfall days. Flooding on intense rainfall days is well understood, but flooding can also occur on days where the rainfall is not particularly extreme, especially if catchments are already saturated. Using the Australian Gridded Climate Data and six dynamically downscaled, Representative Concentration Pathway 8.5, bias adjusted Coupled Model Intercomparison Project 5 models we developed a method to quantify such compounding events to examine how they are changing from 1961 to 2100. We optimized a pre‐existing technique to estimate the antecedent conditions in catchments, combined with daily rainfall. We found that during 1961–2017, the number of compound rainfall events has been decreasing in the four Tasmanian catchments we studied, although the trend was statistically significant in only one case. The intensity of compound rainfall events was found to have increased significantly in some areas. Many future projections place Tasmania at the boundary of a drying trend to the west and wetting trend to the east and the position of this boundary varies between models leading to contrasting projected changes for parts of Tasmania. However, there is projected to be a decline in rainfall to 2100 associated with the southward shift in the storm‐track. Compound rainfall events are projected to decline throughout Tasmania, except in the south which will remain stable to 2100. The intensities are projected to increase in the south and decrease in the west, related to the changing thermodynamics and dynamics of rainfall drivers in the region in a warmer climate.
Publisher: American Meteorological Society
Date: 05-2021
Abstract: The 1-s-resolution U.S. radiosonde data are analyzed for unstable layers, where the potential temperature decreases with increasing altitude, in the troposphere and lower stratosphere (LS). Care is taken to exclude spurious unstable layers arising from noise in the soundings and also to allow for the destabilizing influence of water vapor in saturated layers. Riverton, Wyoming, and Greensboro, North Carolina, in the extratropics, are analyzed in detail, where it is found that the annual and diurnal variations are largest, and the interannual variations are smallest in the LS. More unstable layer occurrences in the LS at Riverton are found at 0000 UTC, while at Greensboro, more unstable layer occurrences in the LS are at 1200 UTC, consistent with a geographical pattern where greater unstable layer occurrences in the LS are at 0000 UTC in the western United States, while greater unstable layer occurrences are at 1200 UTC in the eastern United States. The picture at Koror, Palau, in the tropics is different in that the diurnal and interannual variations in unstable layer occurrences in the LS are largest, with much smaller annual variations. At Koror, more frequent unstable layer occurrences in the LS occur at 0000 UTC. Also, a “notch” in the frequencies of occurrence of thin unstable layers at about 12 km is observed at Koror, with large frequencies of occurrence of thick layers at that altitude. Histograms are produced for the two midlatitude stations and one tropical station analyzed. The log–log slopes for troposphere histograms are in reasonable agreement with earlier results, but the LS histograms show a steeper log–log slope, consistent with more thin unstable layers and fewer thick unstable layers there. Some radiosonde stations are excluded from this analysis since a marked change in unstable layer occurrences was identified when a change in radiosonde instrumentation occurred.
Publisher: American Geophysical Union (AGU)
Date: 29-10-2013
DOI: 10.1002/2013EO440006
Publisher: MDPI AG
Date: 16-04-2018
DOI: 10.3390/F9040210
No related grants have been discovered for Peter Love.