@article {bnh-8124, title = {A characterisation of synoptic weather features often associated with extreme events in southeast Australia: Stage 1 {\textendash} common features of recent events}, number = {679}, year = {2021}, month = {07/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Negatively tilted upper-tropospheric troughs are a synoptic weather pattern that have been associated with the development of thunderstorms and severe weather, including extreme fire weather and tornadoes. While various case studies and some preliminary climatological analysis have been conducted in the past, a thorough investigation of the development of these synoptic features during extreme weather events has not yet been done in Australia or elsewhere. This study aimed to identify how often negatively tilted troughs occur and how often they are associated with extreme storms and fire weather.

The objectives of the project were to:

The major components of the project were:

Review of previously documented cases

January 2003 Canberra fires

July 2014 Perth tornadoes

Climatology

While modern numerical weather prediction (NWP) systems are increasingly capable of resolving the surface weather parameters associated with severe weather events, there are known deficiencies. An example of this is the over-estimation of low winds and under-estimation of high winds common to numerous models. Better understanding of the role of features such as NTT in generating surface weather helps interpretation and refinement of the NWP output, particularly for users of weather data such as emergency services agencies.

Furthermore, as products from NWP such as sub-seasonal to seasonal outlooks become more refined, there is value in recognising the occurrence of potential impacts of NTT that may be resolved at the synoptic or sub-synoptic scale in such model configurations even if the potential severity of the weather parameters are note explicitly resolved. For example, if a sub-seasonal to seasonal model ensemble shows a high probability of a NTT occurrence in a particular region a certain number of weeks in advance, that is useful information for planning and preparedness for emergency services managers.

Thus, this sort of synoptic climatological study in combination with detailed analyses of particular events continues to be of great relevance to natural hazard prediction and management.

Future work

}, keywords = {exterme events, features, Fire, southeast Australia, synoptic, tornado, weather}, issn = {679}, author = {Love, P. and Paul Fox-Hughes and Remenyi, T. and Nick Earl and Dean Rollins and Gabi Mocatta and Rebecca Harris} } @article {bnh-8100, title = {Continental-scale prediction of live fuel moisture content using soil moisture information}, journal = {Agricultural and Forest Meteorology}, volume = {307}, year = {2021}, month = {06/2021}, abstract = {

Live fuel moisture content (LFMC) is a key factor that determines the flammability of vegetation in ecosystems. Soil moisture (SM) is one of the variables that is known to influence plant water use. The present study analyses the LFMC-SM relationship over Australia using gridded, remote sensing-based LFMC and land surface model-based SM products. A lag-correlation analysis conducted over 60 selected sites shows that the strength of the relationship between LFMC and SM varies from site to site and, in general, is moderately strong (median lag-correlation of ~0.5). However, the strength of the relationship changes with vegetation type and also with soil profile depth. At all the sites, SM is found to be a leading indicator of LFMC. The lag also varies with the location and is found to range from days to months. Based on the location-based correlation analysis, we identify the 0-35 cm SM profile (SM0-35cm) to be the best predictor of LFMC. We developed a simple model to predict daily LFMC, where it is hypothesised that daily variations in LFMC from its annual cycle can be predicted using daily deviations from the annual cycle in SM0-35cm. The annual cycles of LFMC and SM0-35cm are modelled using Fourier cosine series. The averaged (over 60 sites) correlation obtained for the validation period is 0.74 when a time-lag of 14 days is assumed at all locations. When the model is applied nationally at a 5 km grid, the normalised root mean squared error for the validation period is found to be less than 25\% in general. The results from the present study highlight a modelling strategy that can be used to address a critical gap in the forecast of spatially and temporally continuous LFMC at regional scales in advance for operational fire management applications.

}, keywords = {AFMS, Fire, JASMIN, JULES, live fuel moisture, Soil moisture}, doi = {https://doi.org/10.1016/j.agrformet.2021.108503}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0168192321001866}, author = {Vinod Kumar and Imtiaz Dharssi and Marta Yebra and Paul Fox-Hughes} } @article {bnh-8253, title = {Coupled fire-atmosphere simulations of five Black Summer fires using the ACCESS-Fire model - Black Summer final report}, number = {705}, year = {2021}, month = {05/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Context

This research builds on previous work completed during the Coupled fire-atmosphere modelling ACCESS-Fire project, by conducting case studies of five major bushfires that occurred across Australia during the 2019-20 summer. The previous work provided valuable insights into the drivers of periods of extreme fire behaviour associated with the Waroona fire in WA, and the Sir Ivan fire in NSW.

The main objectives of this project are: to investigate the meteorological drivers of extreme fire behaviour at five further fire events; to further test the reliability and stability of the model in different environments across Australia; and to support and share learnings from the events of the 2019-20 summer with partner agencies.

The fire events nominated by state jurisdictions for investigation were: Badja Forest (New South Wales), Stanthorpe (Queensland), Green Valley Talmalmo/Corryong\ (NSW/Victoria), Kangaroo Island (South Australia); and Yanchep (Western Australia).

The case studies show that the local context for each fire is important. Each of the fires posed significant challenges in different ways. In the heavily forested areas of NSW and Victoria, the sheer size, intensity, and duration of the fires were distinctive. At other fires, the proximity of local communities and infrastructure posed serious challenges. All fires were active in the overnight period when conventional fire danger indices typically suggest a decrease in fire activity.

The marine boundary layer, local coastal effects and topography combined to generate complex wind flows that influenced the progression of the Kangaroo Island fire. We also studied the way in which the sea breeze circulation interacted with the Yanchep fire, and examined the impact of a prescribed burn on the rate and direction of spread of the Stanthorpe fire under extreme fire weather conditions.

This project has explored gaps in knowledge and understanding of the processes at play during these unusual events by using the Bureau{\textquoteright}s ACCESS-Fire model to examine the local three-dimensional interactions between the fires and the atmosphere. The learnings from this project may be applied to shape future fire weather products and services.

Method

Based on discussions with our partners in fire agencies, together with documents (including photographs and video) and information on fire spread, fuel types and fuel moisture and atypical fire behaviour, we have run a series of simulations and prepared case study chapters for each of the five fires.

The ACCESS-Fire model was initialised using information provided by fire agencies on ignition location or fire line perimeter and fuel type and availability. Several simulations were conducted for each of the fires, with a focus on different time periods of interest and using updated fire polygon boundaries based on available line scan imagery.

The model configuration does not permit the simulations to account for suppression activities by fire agencies, changes in fuel types on the urban interface, or the impact of roads or other fire breaks in reducing the rate of spread of the fire. Another limitation is that the simulations are a single realisation, when in reality, consideration of forecast uncertainty (for example through running an ensemble scheme) would capture a range of potential outcomes.\ 

Learnings from the case studies reinforce and refine some previous learnings from historical fire events and uncover some new insights into the processes driving the periods of unusual fire behaviour that were observed during the 2019/20 season.

Key findings

The case study analyses have provided valuable insights into meteorological aspects of observed extreme fire behaviour during the 2019/20 summer. Key findings for each of the five case studies are included in the individual chapters for each fire and a synthesis is provided here.\ 

The ACCESS-Fire simulations run at 300 m spatial resolution show that some of the most dangerous effects of the fires, in particular damaging and destructive winds, are fire driven and therefore very localised at a much finer scale than current fire weather products.

The depth, elevation and structure of low-level jets over topography was a critical driver of overnight fire activity.\  Given that these jets are driven by larger scale processes (typically synoptic scale), there is an opportunity to develop new tools based on numerical weather prediction output that highlight the location and intensity of these features. Such tools would provide additional information for meteorologists and FBANs on the strength and height of representative winds for input to two-dimensional fire spread models and could be used to alert fire managers to the risk of atypical fire spread in the overnight period.

A key theme that emerged from the case studies and discussions with stakeholders was the consistent occurrence of heatwaves and their influence on boundary layer structure overnight and on inhibiting fuel moisture recovery during the overnight period. Further research quantifying the effects of overnight heatwaves is required to appropriately plan for the increased risk to communities and fire crews in a changing climate, as the frequency of elevated overnight temperatures has increased over the last few decades and is projected to increase further (along with other factors influencing fire activity).\ \ 

Deep moist pyroconvection producing pyrocumulus (pyroCu) or pyrocumulonimbus (pyroCb) clouds was a feature of the 2019-20 fire season and a record number of sustained outbreaks of pyroCbs occurred.\  However, the five fires examined here were not all associated with pyroCb, highlighting that it is not the sole weather phenomenon associated with extreme fire behaviour. In particular, no lightning was detected within the Green Valley Talmalmo fire (that subsequently became the Corryong fire when it burned into Victoria) as it burned through Green Valley, which shows that dangerous tornado-strength fire-generated winds can occur without pyroCb.

The simulations produced fire-generated extreme winds associated with both rotation and straight-line flow, which present a serious hazard. ACCESS-Fire simulated rotating winds in the updraft of the Green Valley Talmalmo/Corryong fire. More work is required to understand the mechanisms for these, they are likely related to the high intensity of the fire, coupled with topographic influences.

Spot fires were an important component in the observed rate of spread, particularly in the forest fires overnight. The extremely dry, drought-affected fuel beds meant that the ignition efficiency of spot fires was enhanced compared to an average season. Inclusion of a spotting parameterisation in ACCESS-Fire would accelerate the forwards fire spread and improve validation of the simulated fire perimeters.\ 

Coastal processes were evident in the simulations of the Kangaroo Island and Yanchep fires. Localised wind effects in the simulations showed interactions between the fire and maritime airmass including sea breeze circulations can modify the updrafts associated with the fire as well as produce rapid transitions in fire intensity around a fire perimeter. Cooler moister air associated with a maritime airmass may not necessarily reduce fire intensity, depending on its depth and penetration inland.

Utilisation - where to from here?

The high level of engagement in this work from a range of stakeholders has demonstrated the value of this research and the appetite for operational application.\ 

The learnings from this work should be incorporated into training packages tailored for fire meteorologists and FBANs that describe characteristics of the local meteorological environment favourable for extreme fire behaviour. Such training will complement other current research and training on fire behaviour aspects such as spotting and potential for pyroCb.

This work, which has been conducted in close collaboration with partners in fire agencies, has demonstrated that a comprehensive understanding of the mechanisms driving fire behaviour requires a multidisciplinary approach. Similarly, the successful application of fire behaviour and meteorology knowledge in operations requires locally connected specialised expertise, combined with tailored modelling tools to inform objective, evidence-based decisions.

The insights gathered from these five case studies have further demonstrated the value of this high resolution coupled modelling approach. In order to progress ACCESS-Fire to an effective operational tool, more robust testing of the model is required, in addition to the more subjective assessments that have been made through the case study work. This would include technical testing, additional sensitivity testing and routine verification.

This project has demonstrated that the Bureau{\textquoteright}s technology and simulation capability, scientific expertise and established relationships with fire agencies can meet the Australian community{\textquoteright}s need to understand the drivers of fire behaviour during the 2019-20 fire season. In doing so, we have further developed and validated our modelling systems and made progress towards their future operational use.

}, keywords = {ACCESS-Fire, black summer, coupled, fire-atmosphere, simulations}, issn = {705}, author = {Mika Peace and Barry Hanstrum and Jesse Greenslade and Dragana Zovko-Rajak and Abhik Santra and Jeffrey Kepert and Paul Fox-Hughes and Harvey Ye and Tasfia Shermin and Jeffrey Jones} } @article {bnh-7839, title = {Mitigating the effects of severe fire, floods and heatwaves through the improvements of land dryness measures and forecasts - final project report}, number = {646}, year = {2021}, month = {02/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

This Bushfire and Natural Hazards CRC project, titled Mitigating the effects of severe fires, floods and heatwaves through the improvements of land dryness measures and forecasts, was a partnership with the Bureau of Meteorology, and examined the use of detailed land surface models, satellite measurements and ground-based observations for the monitoring and prediction of landscape dryness. This project addresses a fundamental limitation in our ability to prepare for fires, floods and heatwaves and is directly linked to pre-event planning as well as forecasting of events. The research conducted in the present project solely focuses on the application of soil and land dryness/moisture in the context of fire danger and fire management practices. The lack of focus on flood and heatwave is circumstantial. The research priorities were set and driven by the requirements of the project end-users, all of them from various fire management agencies across Australia. Hence, the end-use interest was solely on the application of the research in fire management. Nevertheless, it is worth pointing that there is a substantial amount of research literature which establishes the importance of soil moisture in flood and heatwave prediction and applications.

Currently, landscape dryness for fire management is estimated in Australia using simple empirical models developed in the 1960s. The most prominent of those used in Australia are the Keetch-Byram Drought Index (KBDI) and the Soil Dryness Index (SDI). An initial study performed as part of this project suggested that analyses of soil moisture can be improved by using physics-based land surface models, remote sensing measurements and data assimilation.

JASMIN prototype

To address this, the present project developed a standalone prototype land surface modelling system, called Joint UK Land Environment Simulator based Australian Soil Moisture Information (JASMIN) to produce daily soil moisture analyses at 5km resolution and 4 soil layers. Verification against ground-based soil moisture observations shows that this prototype system is significantly more skilful than both KBDI and SDI.

Though JASMIN can supplement many applications that require accurate soil moisture estimates, the biggest beneficiary of this new system will be the fire agencies. The soil moisture estimate from the new system provides a robust alternative to the methods currently used in fire prediction. This is evident from the verifications performed against in situ measurements. KBDI and SDI show large errors over regions where they are used operationally. KBDI, for example, has a large wet bias over southern regions that could undermine fire danger ratings. The JASMIN system can produce reliable soil moisture information over a wide range of land-use types, which potentially extends its applicability to other fields as well. Also, JASMIN is shown to have good skill for both surface and deep soil horizons.

JASMIN calibration

To promote an effective adoption of JASMIN in current operational practices, calibration methods were applied to the native JASMIN soil moisture datasets. The key aim of these methods was to calibrate JASMIN outputs in units of moisture excess to moisture deficit values that range from 0{\textendash}200, as required by McArthur{\textquoteright}s Forest Fire Danger Index (FFDI; McArthur, 1967). The calibration offers a simple, faster and cost-effective way to make significant upgrades to the existing operational systems used by fire and other environmental agencies.

The calibration methods applied were minimum-maximum matching, mean-variance matching, and cumulative distribution function matching. The selection of these calibration methods was based on the potential end-user requirement, whether that is to simply replace the legacy systems with a new product with high skill (e.g., minimum-maximum method), or to replace the existing system that captures the temporal variations better while preserving the climatology of the older system (e.g., mean-variance and cumulative distribution function matching). The latter could be useful if existing operating systems are already tuned to offset the bias in the current soil moisture deficit methods.

Improving high spatial resolution mapping

This project also aimed to improve applications such as fire danger mapping that may require soil moisture information at higher spatial resolution due to the large spatial variability of soil moisture in the landscape. A common practice to overcome such a problem is to employ downscaling methods to increase the spatial scale of the product. Recent advances in optical remote sensing have allowed researchers to use different remote sensing products that reflect soil moisture variability as ancillary information. A method based on a {\textquotedblleft}universal triangle{\textquotedblright} concept is used in several previous studies, which establishes a relationship between soil moisture, vegetation index, and surface radiant temperature from optical remote sensing. This project applied three downscaling methodologies: two based on regression and one based on a physics-based approach.

Results from the downscaling methodologies indicate that it is feasible to improve the spatial resolution of JASMIN using all three disaggregating algorithms and preserve the general large-scale spatial structure seen in JASMIN soil moisture estimates. However, the seasonal means obtained at 1 km show that each product displays characteristic soil moisture spatial variability at fine scales. Results from the comparison with ground-based soil moisture measurements indicate that there is no significant degradation of the bias in the three methods when moving to higher spatial resolution.

Predicting live fuel moisture content

Prediction of the moisture status in live fuels is an important gap in current fire management practices which, if filled, can potentially be useful for spatial and temporal assessment of landscape dryness. The final objective of the project was thus to explore the relationship between soil moisture and live fuel moisture content (LFMC) using the datasets from JASMIN and Australian Flammability Monitoring System (AFMS), respectively. The analysis carried out indicates that soil moisture is a leading indicator of LFMC. This project developed a simple yet skilful model to predict live fuel moisture content for the whole of Australia.

The key variable is the 0-350 mm layer soil moisture derived from the JASMIN system. The modelling strategy pursued consists of a linear combination of two sub-models: one to capture the annual cycle and one to capture the daily variations. A time function represents the LFMC annual cycle model. The daily deviations in LFMC are captured by using a linear regression model with 14-day lagged daily deviations in soil moisture as the input. The daily changes in soil moisture are computed by deviations from its annual cycle.

When evaluated over 60 sites, the approach returned an average R2 of 0.64 with normalised root mean square error values of \<25\% at all sites. As researchers were employing a gridded soil moisture product, this strategy facilitates the reconstruction of past events, as well as data gap filling. The lag of 14 days implies a lead time of 14 days for predicting the LFMC. This has significant operational implications, as daily variations in LFMC can be predicted using soil moisture information from JASMIN on a national scale.

JASMIN is currently run as a prototype research system, with soil moisture analysis done only near-real-time. However, JASMIN can be extended to produce both real-time analysis and forecasts. The prognostic mode can provide soil moisture forecasts for up to 10 days. This means a maximum lead time of 24 days can be achieved by utilising soil moisture forecasts.

JASMIN utilisation

A key focus of the project from its inception was to create pathways for easier utilisation of the project deliverables. This is reflected in both the scientific and technical approaches adopted in this project. For example, the calibration of JASMIN to KBDI and SDI was done to facilitate the ready utilisation of JASMIN in the existing operational system. A total of 8 calibrated JASMIN soil dryness products were developed and made available through the Bureau of Meteorology{\textquoteright}s THREDDS server. The JASMIN soil moisture in volumetric units at 4 layers are also provided via the THREDDS server for interested parties to evaluate. The volumetric soil moisture fields from the top two JASMIN layers (0-100 mm and 100-350 mm) are available via AFMS as well.

The datasets on both THREDDS and AFMS are updated near-real-time. There is a continuing interest in the end-user community in utilising JASMIN for various fire management applications. In that respect, JASMIN has been assessed in the Western Australian Department of Biodiversity, Conservation and Attractions study on tall wet forest fuel availability. Tasmania Parks and Wildlife has also been using JASMIN as a decision-support tool to restrict the use of open fires in national parks. Also, JASMIN data were updated specifically to assist with Tasmanian decision-making for 2018-19 seasonal bushfire assessment workshop and preseason consultative committee on fire weather.

The JASMIN system can produce reliable soil moisture estimates over a wide range of land-use types and can support many applications that require accurate soil moisture information. However, there is still scope for improvements to the JASMIN system, whether it be the skill or the scale.

An immediate focus could be the use of data assimilation techniques to improve the skill of JASMIN. Data assimilation allows uncertainties in land surface model soil moisture to be offset to some extent by routinely updating the hydrological conditions using the information provided by observations on state variables used by land surface models. The assimilation of satellite observations is shown to improve the model soil moisture state. In that respect, the use of NASA{\textquoteright}s land information system (LIS) is being evaluated at the Bureau. The LIS is a complex framework that uses extensible interfaces to allow the incorporation of new domains, land surface models, land surface parameters, meteorological inputs, data assimilation and optimisation algorithms. The extensible nature of these interfaces, and the component style specifications of the system, allow rapid prototyping and development of new applications. The JASMIN system can be incorporated within LIS to facilitate the assimilation of various observation types. Further, it can be leveraged to run JASMIN with an enhanced spatial resolution, desirably at 1 km.

}, keywords = {Floods, forecasts, heatwaves, land dryness, measures, mitigation, severe fire}, issn = {646}, author = {Vinod Kumar and Imtiaz Dharssi and Paul Fox-Hughes} } @article {bnh-8190, title = {Soil and fuel moisture precursors of fire activity during the 2019-20 fire season, in comparison to previous seasons - Black Summer final report}, number = {686}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Australia experienced unprecedented bushfires during the 2019-20 fire season. Millions of hectares were burned, almost 3,000 homes were destroyed, there were 26 fatalities, and communities were exposed to smoke for extended periods.\  Low soil and vegetation moisture content due to antecedent dry conditions were a key driver of fire activity.

This report extends the work in two Bushfire and Natural Hazards CRC projects to examine the 2019-20 fire season:

The national spatial datasets produced by these projects are consistent and regularly updated, separately examining soil and vegetation moisture variability, as both quantities influence fuel availability and therefore fire behaviour.

This project explores the overlaps between these data sets, as well as comparing other available data (including the Australian Landscape Water Balance) to identify atmospheric, soil and fuel moisture characteristics that contributed to fire risk during Black Summer.

Spatially coherent historical and regularly updated soil and fuel moisture datasets are critically important to fire managers so that an accurate, quantifiable assessment of potential fire activity in the landscape can be made, and this can be benchmarked against historical conditions. This information is crucial to making accurate assessments of risk and identifying situations that fall outside of historical records. One of the valuable aspects of JASMIN is that it can also be used in a predictive way and is therefore useful in anticipating soil moisture and therefore fire risk into the future in a quantitative manner on weather (short-term) and seasonal timescales. Research work in the {\textquoteright}Land Dryness{\textquoteright} project also demonstrated the capacity of soil moisture to predict future vegetation moisture content and thus more directly anticipate fire potential.

This project examines the interaction of atmospheric parameters with soil and fuel moisture content over scales of days, weeks to months, and years. Such an integration has not been undertaken previously.\ Consideration of each of these timeframes is important when making accurate assessments of fire risk. The interaction between them is also critical, as a compounding of the individual processes at the different scales occurs and this was seen in the cumulative effects of antecedent dry years, low winter rainfall and heatwaves during the Black Summer.\ 

This project examined six fire events that were nominated for investigation by the relevant jurisdictions. The fires are:

The scope of the project included examining the following:

Key findings of the project include:\ 

The findings confirm impressions of fire practitioners regarding the extremity of conditions antecedent to the 2019-20 fire season. Importantly, the datasets used in the project present a measurable and spatially coherent approach to estimating fire risk from observed and modelled soil and fuel moisture. Operational application of the datasets and approaches used here will assist in producing accurate soil and vegetation moisture forecasts for prediction of fire risk in the future.

Some immediate benefits for fire managers of this work include:

Each of the meteorological and moisture variables investigated in this study contributed useful information to an understanding of increased fire risk at each site during the 2019-20 Australian summer. Fuel moisture content provided perhaps the most immediate indicator of present fire risk. Soil moisture content permitted an assessment of future changes in fuel moisture content. Both of these integrated changes in meteorological parameters. As such, the meteorological parameters (temperature, precipitation, atmospheric moisture represented by vapour pressure) contributed an understanding of why soil and fuel moisture changed in the ways that they did and offered information on how they would change in the future. Monitoring these quantities can help fire and land managers understand how and why fire risk changes across a landscape.\ 

Future work

This project was conducted over a short time period with one objective being to establish a pathway for future research and operational application.

The following opportunities for future research with likely operational benefits have been identified:

In summary, better understanding and spatial mapping of the influence of atmospheric, soil and fuel moisture will assist fire and land managers predict fire risk, which is critical for strategic and tactical planning. Many of the recommendations could be inclusions to the Australian Fire Danger Rating System (AFDRS), and therefore of immediate benefit to fire and land managers following the introduction of the AFDRS to operational use over the next two fire seasons.

}, keywords = {black summer, Fire, fire activity, fuel, moisture, precursors, soil}, issn = {686}, author = {Paul Fox-Hughes and Marta Yebra and Shukhrat Shokirov and Vinod Kumar and Dowdy, Andrew J and Pandora Hope and Mika Peace and Sugata Narsey and Francois Delage and Huqiang Zhang} } @article {bnh-7470, title = {Exploring the soil moisture-live fuel moisture relationship}, number = {624}, year = {2020}, month = {10/2020}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Live fuel moisture content is a key factor that determines the flammability of vegetation in ecosystems. Prediction of live fuel moisture content is inherently a very difficult problem since it is modulated by the complex physiological, phenological and ecological processes characteristic of the plant species. Soil moisture is one of the key variables that is known to influence plant water use. Recently, a new live fuel moisture content near-real-time product has been developed for Australia using a radiative transfer model inversion technique on the MODerate Resolution Imaging Spectroradiometer reflectance data. This live fuel moisture content product forms the basis of the Australian Flammability Monitoring System. At the same time, an advanced soil moisture analysis system has been developed by the Bureau of Meteorology recently, called the Joint United Kingdom Land Environment Simulator based Soil Moisture Information (JASMIN). JASMIN can estimate soil moisture at 5 km resolution on a daily timestep for the whole of Australia.

The present study brings together the above two products and explores the live fuel moisture content{\textendash}soil moisture relationship on a national scale. This study will report the preliminary work carried out in understanding live fuel moisture content{\textendash}soil moisture relationship and suggests an approach that may be constructive in advancing the ability to predict live fuel moisture content reliably to support fire management. A preliminary analysis is being conducted over 60 selected locations where JASMIN is found to have good skill. These 60 sites together represent a range of land cover types and climate zones typical of the Australian landscape. All the possible soil moisture profiles that can be derived from the four JASMIN soil layers are used for the analysis. Lag-correlation analysis shows that the strength of the relationship between live fuel moisture content and soil moisture varies from site to site and in general, is moderately strong (median lag-correlation of ~0.5). However, the strength of the relationship varies with vegetation type and also with soil profile depth. At all the sites, soil moisture is found to be an (important) leading indicator of live fuel moisture content. The lag also varies with the location and is found to range from days to months. Except for the forested sites, the top two soil layers exhibit a higher correlation with live fuel moisture content compared to the deeper layers. We develop a simple model to predict live fuel moisture content. The model is found to have good skill with an average R2 of 0.64 over the 60 sites. The normalized root mean square error for the model prediction is found to be less than 25\% in general.

}, keywords = {live fuel moisture, Soil moisture}, issn = {624}, author = {Vinod Kumar and Imtiaz Dharssi and Marta Yebra and Paul Fox-Hughes} } @article {bnh-6237, title = {Disaggregation of JASMIN soil moisture product to 1KM resolution}, number = {521}, year = {2019}, month = {12/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

Fire intensity, spread rate, and ignition are very sensitive to fuel dryness which in turn is strongly linked to soil moisture deficit. Though the value of soil moisture deficit in predicting fire danger has been long established, very few fire danger rating systems employ a comprehensive methodology to estimate it. Most such fire danger rating systems use very simple empirical water balance models which are found to have errors. The Bureau of Meteorology has recently developed a prototype, highresolution, land surface modelling based, state-of-the-art soil moisture analysis for Australia. The product, called Joint United Kingdom Land Environment Simulator (JULES) based Australian Soil Moisture Information (JASMIN), has a spatial resolution of 5 km at hourly timesteps. However, applications like fire danger mapping may require soil moisture information at higher spatial resolution due to the large spatial variability of soil moisture in the landscape. We focus on some of the research carried out to downscale the JASMIN product from 5 km to 1 km spatial resolution. We discuss the application of three downscaling algorithms: two regression-based methods and one with a theoretical basis. The three methods applied are based on the well-known surface temperature {\textendash} vegetation index space. We present an overview of the application of each method, along with an evaluation and comparison against each other and against ground-based soil moisture observations. Results from comparison with ground-based soil moisture measurements indicate that there is no significant degradation of the bias in the three methods, when going into higher spatial resolutions. However, the regression methods, in general, fail to capture the observed temporal variability. The theoretical based method, on the other hand, provides a temporal correlation of 0.81 and captures the skill of the parent JASMIN product.

}, keywords = {dryness, Emergency management, JASMIN, resolution, Soil moisture}, issn = {521}, author = {Vinod Kumar and Imtiaz Dharssi and Paul Fox-Hughes} } @article {bnh-6392, title = {Evolution of an extreme Pyrocumulonimbus-driven wildfire event in Tasmania, Australia}, journal = {Natural Hazards and Earth System Sciences}, year = {2019}, month = {12/2019}, abstract = {

Extreme fires have substantial adverse effects on society and natural ecosystems. Such events can be associated with intense coupling of fire behaviour with the atmosphere, resulting in extreme fire characteristics such as pyrocumulonimbuscloud (pyroCb) development. Concern that anthropogenic climate change is increasing the occurrence of pyroCbs globally is driving more focused research into these meteorological phenomena. Using 6-minute scans from a nearby weather radar, we describe the development of a pyroCb during the afternoon of 4 January 2013 above the Forcett-Dunalley fire in south-eastern Tasmania. We relate storm development to: (1) near-surface weather using the McArthur Forest Fire Danger Index (FFDI), and the C-Haines Index, a measure of the vertical atmospheric stability and dryness both derived from gridded weather reanalysis for Tasmania (BARRA-TA), and (2) a chronosequence of fire severity derived from remote sensing. We show that the pyroCb rapidly developed over a 24-minute period in the afternoon of 4 January, with the cloud top reaching a height of 15 km. The pyroCb was associated with a highly unstable atmosphere (C-Haines 10-11) and Severe-marginally Extreme (FFDI 60-75) near-surface fire weather, and formed over an area of forest that was severely burned (total crown defoliation). We use spatial patterns of elevated fire weather in Tasmania, and fire weather during major runs of large wildfires in Tasmania for the period 2007-2016 to geographically and historically contextualise this pyroCb event. Although the Forcett-Dunalley fire is the only known record of a pyroCb in Tasmania, our results show that eastern and south-eastern Tasmania are prone to the conjunction of high FFDI and C-Haines values that have been associated with pyroCb development. Our findings have implications for fire weather forecasting and wildfire management, and highlight the vulnerability of southeast Tasmania to extreme fire events.

}, keywords = {C-Haines, extreme fire, fire severity, Fire weather, McArthur Forest Fire Danger Index, pyrocumulonimbus, smoke plume injection, Tasmania, wildland fire}, doi = {https://doi.org/10.5194/nhess-2019-354}, url = {https://www.nat-hazards-earth-syst-sci-discuss.net/nhess-2019-354/}, author = {Mercy Ndalila and Grant Williamson and Paul Fox-Hughes and Jason J. Sharples and David Bowman} } @conference {bnh-6411, title = {Fire weather and prototype fire danger ratings for the Gell River fire, Tasmania}, booktitle = {Bushfire and Natural Hazards CRC Research Day AFAC19}, year = {2019}, month = {12/2019}, address = {Melbourne}, abstract = {

We provide a preliminary analysis of the meteorology of key aspects of the Gell River fire in Tasmania during late December 2018 and early January 2019, including the lightning storm that ignited the fire, and conditions on 4 January 2019, when the fire increased substantially in size. We also briefly assess the performance of the Australian National Fire Danger Rating System (AFDRS) Research Prototype available on 4 January against observations of fire spread and routine McArthur Forest Fire Danger forecasts.

The Gell River fire occurred within a context of declining October {\textendash} April rainfall in western Tasmania over the last two decades, in comparison to the average rainfall for the period since 1900 (Fig. 1, Bureau of Meteorology and CSIRO (2018)). It was one of several large fires that competed for fire management resources over an extended period during the 2018-2019 Tasmanian fire season. The fire impacted natural values including those of the Tasmanian Wilderness World Heritage Area (TWWHA) and risked spreading into parts of the iconic Mt Field National Park, as well as threatening a number of communities in the Derwent Valley, particularly Maydena. The Gell River fire also threatened major electrical transmission infrastructure connecting the large Gordon-Pedder power generation facility in the west of Tasmania to population centres in the east, and burnt approximately 500 ha of a 5,000 ha pine plantation. On 4 January, thick smoke from the fire crossed over the Greater Hobart area, sparking concern and raising awareness within the wider community about the fire activity (Fig. 2).

}, keywords = {Fire behaviour, Fire weather, modelling}, url = {https://knowledge.aidr.org.au/resources/australian-journal-of-emergency-management-monograph-series/}, author = {Paul Fox-Hughes and Stuart Matthews and Chris Collins and Saskia Grootemaat and Jennifer J Hollis and Alexander Holmes and Belinda Kenny and John Runcie and Samuel Sauvage} } @conference {bnh-6532, title = {JASMIN: a high-resolution soil moisture analysis system for fire prediction}, booktitle = {AFAC19 powered by INTERSCHUTZ - Bushfire and Natural Hazards CRC Research Forum}, year = {2019}, month = {12/2019}, publisher = {Australian Institute for Disaster Resilience}, organization = {Australian Institute for Disaster Resilience}, address = {Melbourne}, abstract = {

Soil moisture is found to be a key factor that influences fuel moisture content. Consequently, operational forest fire prediction systems typically include soil moisture as one of the inputs for fire behaviour calculations. The soil moisture input to these fire prediction models is usually provided in the form of moisture deficit. There is evidence that the current operational methods used in Australia for fire prediction perform poorly in estimating soil moisture status. A research project was initiated in partnership with the Bushfire and Natural Hazards Cooperative Research Centre to develop an advanced, state-of-the-art soil moisture analysis for Australia. Consequently, a prototype, high-resolution, land surface modelling-based soil moisture analysis called JULES based Soil Moisture Information (JASMIN) has been developed. JASMIN can provide hourly moisture estimates for four soil layers, at a spatial resolution of 5 km.

The present paper will discuss the evaluation of JASMIN carried out against observations from ground-based networks. Among the results, the mean Pearson{\textquoteright}s correlation for surface soil moisture across three in-situ networks is found to be between 0.78 and 0.85. We also focus on the research carried out to downscale the JASMIN product from 5 km to 1 km spatial resolution. The downscaling research is motivated by the desirable impact a higher resolution soil moisture product can provide for fire prediction, considering the high spatial variability in soil moisture and fuel moisture. We discuss the application of three downscaling algorithms: two regressionbased methods and one with a theoretical basis. The three methods applied in the present study are based on the information derived from characterizing a two-dimensional surface temperature/vegetation index scatterplot domain obtained from thermal and optical remote sensing observations. We present an overview of the application of each method, along with an evaluation against ground-based soil moisture observations. Evaluation results indicate that the regression methods, in general, fail to capture the observed temporal variability. The theoretically based method, on the other hand, provides a temporal correlation of 0.81 and captures the skill of the parent JASMIN product.

Download the full non-peer reviewed research proceedings\ from the Bushfire and Natural Hazards CRC Research Forumhere.

}, keywords = {analysis system, fire prediction, Preparedness, risk management, Soil moisture}, url = {https://knowledge.aidr.org.au/resources/australian-journal-of-emergency-management-monograph-series/}, author = {Vinod Kumar and Imtiaz Dharssi and Paul Fox-Hughes} } @article {bnh-5804, title = {Mitigating the effects of severe fires, floods and heatwaves through the improvements of land dryness measures and forecasts - annual report 2018-2019}, number = {507}, year = {2019}, month = {08/2019}, institution = {Bushfire and Natural Hazards CRC}, address = {Melbourne}, abstract = {

The Bushfire and Natural Hazards CRC project titled {\textquotedblleft}Mitigating the Effects of Severe Fires, Floods and Heatwaves through the Improvements of Land Dryness Measures and Forecasts{\textquotedblright} examines the use of detailed land surface models,
satellite measurements and ground-based observations for the monitoring and prediction of landscape dryness. This project will address a fundamental limitation in our ability to prepare for fires, floods and heatwaves and is directly
linked to pre-event planning as well as forecasting of events.

Currently landscape dryness is estimated in Australia using simple empirical models developed in the 1960{\textquoteright}s. The most prominent of those used in Australia are the Keetch-Byram Drought Index (KBDI; Keetch \& Byram 1968) and the Soil Dryness Index (SDI; Mount 1972). An initial study performed as part of this project suggest that analyses of soil moisture can be improved by using physically based land surface models, remote sensing measurements and data assimilation. The project has developed a stand-alone prototype land surface modelling system to produce daily soil moisture analyses at 5km resolution and at 4 soil layers. Verification against ground-based soil moisture observations show that this prototype system is significantly more skilful than both KBDI and SDI.

The present report documents the activities undertaken in 2018-2019. A major focus for the year has been on the downscaling of soil moisture from the JASMIN system, enhancing the spatial resolution from 5 km to 1km. Applications like fire danger mapping may require soil moisture information at higher spatial resolution due to the large spatial variability of soil moisture in the landscape. Another major outcome from the project during this year was the publication of a peerreviewed paper in the highly regarded Agriculture and Forest Meteorology journal.

}, keywords = {Emergency management, fires, Floods, Forecasting, heatwaves, land dryness}, issn = {507}, author = {Vinod Kumar and Paul Fox-Hughes and Imtiaz Dharssi} } @conference {bnh-4794, title = {Evaluation and calibration of a land surface based soil moisture for fire danger ratings}, booktitle = {AFAC18}, year = {2018}, month = {09/2018}, publisher = {Bushfire and Natural Hazards CRC}, organization = {Bushfire and Natural Hazards CRC}, address = {Perth}, abstract = {

We present the evaluation of high-resolution, JASMIN soil moisture analysis developed for Australia. The prototype JASMIN system has been developed primarily for use in fire and land management. JASMIN produce hourly soil moisture estimates over four soil layers at 5 km horizontal resolution. We evaluate JASMIN against three ground-based networks in Australia. Among the results, the median Pearson{\textquoteright}s correlation obtained for surface soil moisture across the observation networks for JASMIN is between 0.78 and 0.85. JASMIN generally has a better skill than the Keetch-Byram Drought Index and Soil Dryness Index models used operationally in Australia. We also apply and evaluate a few rescaling approaches to the JASMIN soil moisture to facilitate its use in the current operational fire danger rating system. Minimummaximum matching, mean-variance matching, and cumulative distribution function (CDF) matching are the rescaling approaches applied. Validation of the rescaled products is performed using ground-based observations and MODIS fire radiative power data. The rescaling readily enables fire agencies to utilize the JASMIN product in their existing fire prediction models. However, the potential of JASMIN is greatest in the National Fire Danger Rating System (NFDRS), currently being prototyped across Australia. Particularly, the ability of JASMIN to estimate soil moisture at several levels is expected to be advantageous in the NFDRS. For example, the Spinifex fuel model implemented in the current NFDRS prototype uses 0-10cm soil moisture as an input.\  This soil moisture information is available natively in JASMIN.

}, author = {Vinod Kumar and Imtiaz Dharssi and Paul Fox-Hughes} } @conference {bnh-3879, title = {An assessment of the viability of prescribed burning as a management tool under a changing climate: a Tasmanian case study}, booktitle = {AFAC17}, year = {2017}, month = {09/2017}, publisher = {Bushfire and Natural Hazards CRC}, organization = {Bushfire and Natural Hazards CRC}, address = {Sydney}, abstract = {

Fire danger is projected to increase across Tasmania under climate change, with the fire season starting earlier and lasting longer. Prescribed burning is currently the only effective method of managing bushfire risk at the landscape scale in Tasmania. It is generally carried out during autumn and spring, when weather conditions allow low intensity burns to be safely managed. We investigated the changing opportunities for prescribed burning in Tasmania in the near future (2021-2040) and towards the end of the century (2081-2100) under a high emissions scenario (SRES A2). We assessed monthly changes in the climate variables that determine when prescribed burning can be applied, including rainfall, temperature, fuel moisture and atmospheric stability. We found that in the future, weather conditions conducive to safe, low intensity burning may occur less frequently. Increased Drought Factor and Soil Dryness Index in spring and autumn, resulting from rising temperatures and reduced rainfall, may result in increased fuel availability. These trends become evident in the near future (2021-2040), followed by substantial changes by the end of the century (2081-2100). This suggests a significant reduction in the ability to safely conduct and contain prescribed burns in the coming decades. These findings have important consequences for the ability to manage bushfire risk using prescribed burning in the future. The timing and resourcing of prescribed burning may be affected, with a narrower window of suitable weather conditions for burning. Alternative methods to build resilience to bushfire risk may need to be considered.

}, author = {Harris, R. M. B. and Remenyi, T. and Paul Fox-Hughes and Love, P. and Phillips, H. E. and Bindoff, L. P.} } @article {bnh-3282, title = {Natural hazards in Australia: extreme bushfire}, journal = {Climatic Change}, volume = {139}, year = {2016}, month = {11/2016}, pages = {85-99}, chapter = {85}, abstract = {

Bushfires are one of the most frequent natural hazards experienced in Australia. Fires play an important role in shaping the landscape and its ecological dynamics, but may also have devastating effects that cause human injuries and fatalities, as well as broad-scale environmental damage. While there has been considerable effort to quantify changes in the occurrence of bushfire in Australia, a comprehensive assessment of the most extreme bushfire cases, which exact the greatest economic and environmental impacts, is lacking. In this paper we reflect upon recently developed understanding of bushfire dynamics to consider (i) historical changes in the occurrence of extreme bushfires, and (ii) the potential for increasing frequency in the future under climate change projections. The science of extreme bushfires is still a developing area, thus our conclusions about emerging patterns in their occurrence should be considered tentative. Nonetheless, historical information on noteworthy bushfire events suggests an increased occurrence in recent decades. Based on our best current understanding of how extreme bushfires develop, there is strong potential for them to increase in frequency in the future. As such there is a pressing need for a greater understanding of these powerful and often destructive phenomena.

}, doi = {10.1007/s10584-016-1811-1}, url = {http://link.springer.com/article/10.1007/s10584-016-1811-1}, author = {Jason J. Sharples and Geoffrey J. Cary and Paul Fox-Hughes and Mooney, Scott and Jason P. Evans and Fletcher, Michael-Shawn and Michael Fromm and Grierson, Pauline and Rick McRae and Baker, Patrick} } @proceedings {BF-3040, title = {Progress in understanding springtime fire weather in Tasmania}, year = {2010}, publisher = {R.P. Thornton (Ed) 2011, {\textquoteleft}Proceedings of Bushfire CRC \& AFAC 2010 Conference Science Day{\textquoteright} 1 September 2011, Sydney Australia, Bushfire CRC}, address = {Sydney, Australia}, issn = {978-0-9806759-9-3}, author = {Paul Fox-Hughes} }