scholarly journals Meteorological drivers of extreme fire behaviour during the Waroona bushfire, Western Australia, January 2016

2017 ◽  
Vol 67 (2) ◽  
pp. 79
Author(s):  
Mika Peace ◽  
Lachlan McCaw ◽  
Bradley Santos ◽  
Jeffrey D. Kepert ◽  
Neil Burrows ◽  
...  
Keyword(s):  
Fire Spread ◽  
Fire Behaviour ◽  
Near Surface ◽  
Lightning Strikes ◽  
Downslope Winds ◽  
Large Numbers ◽  
Predictive Methods ◽  
Meteorological Observations ◽  
Extreme Fire

The Waroona bushfire burnt 69,000 ha south of Perth in January 2016. During the first two days of the fire, there were two pyrocumulonimbus (pyroCb) events and two destructive evening fire runs. Over 160 homes were destroyed and there were two fatalities. This case study examines in detail the links between the meteorological observations and the fire behaviour reconstruction.The first pyroCb developed on Wednesday 6 January 2016, when the fire made an unexpectedly fast run in light prevailing winds. The pyroCb produced lightning strikes that ignited a new fire downwind of the main head fire. A second pyroCb developed on Thursday morning, against normal diurnal thunderstorm trends. Similar to the previous evening, the fire spread faster than expected, given the near-surface meteorological conditions.On both evenings there were destructive ember storms over the towns of Waroona (Wednesday) and Yarloop (Thursday). Examination of the meteorological observations has linked these ember showers to the onset of downslope winds, locally known as `scarp winds'. As downslope winds are associated with strong localised turbulence, they provide a mechanism for transport of large numbers of firebrands.The periods of extreme fire behaviour at Waroona were against normal diurnal expectations and did not coincide with the highest observed Fire Danger Index (FDI) values, which occurred at around 1600 LT. This study links both pyroCb events to accelerated fire spread, which presents a hazard to firefighters that is not accounted for in traditional, surface based methods of fire prediction. Downslope winds similar to those that impacted the Waroona fire occur at many locations. They provide a highly localised mechanism for destructive evening ember showers.This investigation into the Waroona fire describes the potential impacts of fireatmosphere feedback processes. Consequently, it highlights the need for predictive methods and tools that anticipate fire behaviour which is not steady-state. Planned simulations using a coupled fire-atmosphere model will allow further insights into features of this case study.

scholarly journals The 2018 Camp Fire: Meteorological Analysis Using In Situ Observations and Numerical Simulations

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 47 ◽  
Author(s):  
Matthew J. Brewer ◽  
Craig B. Clements
Keyword(s):  
Fire Spread ◽  
Meteorological Conditions ◽  
California History ◽  
Central California ◽  
Rossby Wave Breaking ◽  
Forecast Models ◽  
Downslope Windstorms ◽  
Meteorological Observations

The November 2018 Camp Fire quickly became the deadliest and most destructive wildfire in California history. In this case study, we investigate the contribution of meteorological conditions and, in particular, a downslope windstorm that occurred during the 2018 Camp Fire. Dry seasonal conditions prior to ignition led to 100-h fuel moisture contents in the region to reach record low levels. Meteorological observations were primarily made from a number of remote automatic weather stations and a mobile scanning Doppler lidar deployed to the fire on 8 November 2018. Additionally, gridded operational forecast models and high-resolution meteorological simulations were synthesized in the analysis to provide context for the meteorological observations and structure of the downslope windstorm. Results show that this event was associated with mid-level anti-cyclonic Rossby wave breaking likely caused by cold air advection aloft. An inverted surface trough over central California created a pressure gradient which likely enhanced the downslope winds. Sustained surface winds between 3–6 m s−1 were observed with gusts of over 25 m s−1 while winds above the surface were associated with an intermittent low-level jet. The meteorological conditions of the event were well forecasted, and the severity of the fire was not surprising given the fire danger potential for that day. However, use of surface networks alone do not provide adequate observations for understanding downslope windstorm events and their impact on fire spread. Fire management operations may benefit from the use of operational wind profilers to better understand the evolution of downslope windstorms and other fire weather phenomena that are poorly understood and observed.

Field Guide: Fire in Dry Eucalypt Forest

2008 ◽  
Author(s):  
JS Gould ◽  
WL McCaw ◽  
NP Cheney ◽  
PF Ellis ◽  
S Matthews
Keyword(s):  
Fire Spread ◽  
Flame Height ◽  
Fire Behaviour ◽  
Effective Response ◽  
Understorey Vegetation ◽  
Near Surface ◽  
Field Guide ◽  
Eucalypt Forest ◽  
Rate Of Spread ◽  
Eucalypt Forests

An effective response to bushfires relies on accurate predictions of fire behaviour, particularly the rate of spread, intensity and ‘spotting’. This field guide has been developed to provide a systematic method for assessing fuel hazard and predicting potential fire behaviour in dry eucalypt forest. It will assist in making vital decisions that ensure the protection of fire crews and the community. This guide integrates Project Vesta research findings with the Victorian Overall Fuel Hazard Guide and is applicable to dry eucalypt forests throughout southern Australia. Fuel assessment is based on the hazard scoring system employed during Project Vesta which investigated the effects of fuel age and understorey vegetation structure on fire behaviour in these forests. Information provided in this guide can be used to: Define and identify different fuel layers and components of fuel structure and hazard; Determine the hazard score of surface and near-surface fuel layers and the height of the near-surface fuel for fire spread prediction; Determine elevated fuel height for flame height prediction; and determine surface fuel hazard score and bark hazard score for spotting distance prediction. The Field Guide provides tables to predict the potential rate of spread of a bushfire burning in dry eucalypt forest under summer conditions, and can also be used to predict flame height and maximum spotting distance. The guide also allows users to determine the moisture content of fine dead fuels throughout the day, and to account for the effect of slope on the rate of spread of a fire.

A case study on fractal simulation of forest fire spread

2000 ◽  
Vol 43 (S1) ◽  
pp. 104-112 ◽  
Author(s):  
Qijiang Zhu ◽  
Taizong Rong ◽  
Rui Sun
Keyword(s):  
Forest Fire ◽  
Fire Spread ◽  
Fractal Simulation

A hydrochemical and isotopic case study around a near surface radioactive waste disposal

2007 ◽  
Vol 95 (1) ◽  
Author(s):  
Zs. Szántó ◽  
É. Svingor ◽  
I. Futó ◽  
L. Palcsu ◽  
M. Molnár ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Waste Treatment ◽  
Radioactive Waste Disposal ◽  
Ion Chemistry ◽  
Continuous Transition ◽  
Near Surface ◽  
Disposal Facility ◽  
Treatment And Disposal ◽  
Site Characterisation

As part of the site characterisation program for the near surface radioactive waste treatment and disposal facility (RWTDF) at Püspökszilágy, Hungary, water quality and environmental isotope investigations have been carried out. Water samples for major ion chemistry, tritium,The chemical composition of groundwaters presented a continuous transition from waters situated on one side to waters on the top and on the other slope of the disposal suggesting the mixing of the three hydrochemical “endmembers”.Most of δ

Evaporite Palynology: a case study on the Permian (Lopgingian) Zechstein Sea

2021 ◽  
pp. jgs2020-174
Author(s):  
Martha E. Gibson ◽  
David J. Bodman
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Rapid Growth ◽  
Western Europe ◽  
Thermal Maturity ◽  
Near Surface ◽  
Wide Range ◽  
Terrestrial Environments ◽  
Insight Into

Evaporites characterize the Lopingian of Europe but present obstacles for biostratigraphic analysis. Here we present a case study for processing the Lopingian Zechstein Group evaporites of central-western Europe for the recovery of palynomorph assemblages. We demonstrate that full recovery is easily achieved with two main modes of palynomorph preservation observed; palynomorphs are either exceptionally well-preserved and orange-brown in colour, or poorly-preserved, brown-black, opaque and fragmented. The latter are reminiscent of palynomorphs of high thermal maturity. However, we propose that the intact nature of preservation is a result of the rapid growth of near-surface halite crystals, with their darkening a consequence of locally-enhanced heat flux due to the relatively high thermal conductivity of salt. This case study has enabled novel insight into an otherwise undescribed environment, and demonstrates the utility and possibility of extracting palynomorphs from a variety of rock salt types. This method should be applicable to a wide range of ancient evaporite and could also be applied to other Permian evaporite systems, which are used as analogues for extra-terrestrial environments.

scholarly journals Increasing the accuracy and temporal resolution of two-filter radon–222 measurements by correcting for the instrument response

2016 ◽  
Vol 9 (6) ◽  
pp. 2689-2707 ◽  
Author(s):  
Alan D. Griffiths ◽  
Scott D. Chambers ◽  
Alastair G. Williams ◽  
Sylvester Werczynski
Keyword(s):  
Temporal Resolution ◽  
Radon Concentration ◽  
Time Response ◽  
Slow Time ◽  
Flow Loop ◽  
Detector Performance ◽  
Convective Boundary ◽  
Near Surface ◽  
Instrument Response

Abstract. Dual-flow-loop two-filter radon detectors have a slow time response, which can affect the interpretation of their output when making continuous observations of near-surface atmospheric radon concentrations. While concentrations are routinely reported hourly, a calibrated model of detector performance shows that ∼ 40 % of the signal arrives more than an hour after a radon pulse is delivered. After investigating several possible ways to correct for the detector's slow time response, we show that a Bayesian approach using a Markov chain Monte Carlo sampler is an effective method. After deconvolution, the detector's output is redistributed into the appropriate counting interval and a 10 min temporal resolution can be achieved under test conditions when the radon concentration is controlled. In the case of existing archived observations, collected under less ideal conditions, the data can be retrospectively reprocessed at 30 min resolution. In one case study, we demonstrate that a deconvolved radon time series was consistent with the following: measurements from a fast-response carbon dioxide monitor; grab samples from an aircraft; and a simple mixing height model. In another case study, during a period of stable nights and days with well-developed convective boundary layers, a bias of 18 % in the mean daily minimum radon concentration was eliminated by correcting for the instrument response.

scholarly journals Evaluation of Forecasts of a Convectively Generated Bore Using an Intensively Observed Case Study from PECAN

2018 ◽  
Vol 146 (9) ◽  
pp. 3097-3122 ◽  
Author(s):  
Aaron Johnson ◽  
Xuguang Wang ◽  
Kevin R. Haghi ◽  
David B. Parsons
Keyword(s):  
Cross Sections ◽  
Turbulent Mixing ◽  
Weather Research And Forecasting ◽  
Cold Pool ◽  
Model Errors ◽  
Near Surface ◽  
Cold Pools ◽  
Convection Model

Abstract This paper presents a case study from an intensive observing period (IOP) during the Plains Elevated Convection at Night (PECAN) field experiment that was focused on a bore generated by nocturnal convection. Observations from PECAN IOP 25 on 11 July 2015 are used to evaluate the performance of high-resolution Weather Research and Forecasting Model forecasts, initialized using the Gridpoint Statistical Interpolation (GSI)-based ensemble Kalman filter. The focus is on understanding model errors and sensitivities in order to guide forecast improvements for bores associated with nocturnal convection. Model simulations of the bore amplitude are compared against eight retrieved vertical cross sections through the bore during the IOP. Sensitivities of forecasts to microphysics and planetary boundary layer (PBL) parameterizations are also investigated. Forecasts initialized before the bore pulls away from the convection show a more realistic bore than forecasts initialized later from analyses of the bore itself, in part due to the smoothing of the existing bore in the ensemble mean. Experiments show that the different microphysics schemes impact the quality of the simulations with unrealistically weak cold pools and bores with the Thompson and Morrison microphysics schemes, cold pools too strong with the WDM6 and more accurate with the WSM6 schemes. Most PBL schemes produced a realistic bore response to the cold pool, with the exception of the Mellor–Yamada–Nakanishi–Niino (MYNN) scheme, which creates too much turbulent mixing atop the bore. A new method of objectively estimating the depth of the near-surface stable layer corresponding to a simple two-layer model is also introduced, and the impacts of turbulent mixing on this estimate are discussed.

scholarly journals Optimization of the Mashaer Shuttle-Bus Service in Hajj: Arafat-Muzdalifah Case Study

Information ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 496
Author(s):  
Omar Hussain ◽  
Emad Felemban ◽  
Faizan Ur Rehman
Keyword(s):  
Optimal Number ◽  
Improve Performance ◽  
Large Numbers ◽  
Proposed Model ◽  
Holy Places ◽  
Essential Form ◽  
Service Delays ◽  
Customer Dissatisfaction ◽  
Bus Service

Hajj, the fifth pillar of Islam, is held annually in the month of Dhul Al-Hijjah, the twelfth month, in the Islamic calendar. Pilgrims travel to Makkah and its neighbouring areas—Mina, Muzdalifah, and Arafat. Annually, about 2.5 million pilgrims perform spatiotemporally restricted rituals in these holy places that they must execute to fulfil the pilgrimage. These restrictions make the task of transportation in Hajj a big challenge. The shuttle bus service is an essential form of transport during Hajj due to its easy availability at all stages and ability to transport large numbers. The current shuttle service suffers from operational problems; this can be deduced from the service delays and customer dissatisfaction with the service. This study provides a system to help in planning the operation of the service for one of the Hajj Establishments to improve performance by determining the optimal number of buses and cycles required for each office in the Establishment. We will also present a case study in which the proposed model was applied to the non-Arab Africa Establishment shuttle service. At the same time, we will include the mechanism for extracting the information required in the tested model from the considerably large GPS data of 20,000+ buses in Hajj 2018.

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