scholarly journals Drivers of long-distance spotting during wildfires in south-eastern Australia

2020 ◽  
Vol 29 (6) ◽  
pp. 459 ◽  
Author(s):  
Michael A. Storey ◽  
Owen F. Price ◽  
Jason J. Sharples ◽  
Ross A. Bradstock
Keyword(s):  
Weather Conditions ◽  
Long Distance ◽  
Eastern Australia ◽  
Optical Line ◽  
Fire Area ◽  
Strong Winds ◽  
Upper Level ◽  
Behaviour Models ◽  
Steep Slopes ◽  
Spot Fires

We analysed the influence of wildfire area, topography, fuel, surface weather and upper-level weather conditions on long-distance spotting during wildfires. The analysis was based on a large dataset of 338 observations, from aircraft-acquired optical line scans, of spotting wildfires in south-east Australia between 2002 and 2018. Source fire area (a measure of fire activity) was the most important predictor of maximum spotting distance and the number of long-distance spot fires produced (i.e. >500m from a source fire). Weather (surface and upper-level), vegetation and topographic variables had important secondary effects. Spotting distance and number of long-distance spot fires increased strongly with increasing source fire area, particularly under strong winds and in areas containing dense forest and steep slopes. General vegetation descriptors better predicted spotting compared with bark hazard and presence variables, suggesting systems that measure and map bark spotting potential need improvement. The results from this study have important implications for the development of predictive spotting and wildfire behaviour models.

Unprecedented long-distance transport of macroscopic charcoal from a large, intense forest fire in eastern Australia: Implications for fire history reconstruction

The Holocene ◽  
2020 ◽  
Vol 30 (7) ◽  
pp. 947-952 ◽  
Author(s):  
Craig Woodward ◽  
Heather Ann Haines
Keyword(s):  
Fire History ◽  
Sediment Cores ◽  
Fire Regimes ◽  
Fire Intensity ◽  
Long Distance ◽  
Long Distance Transport ◽  
Eastern Australia ◽  
Upper Level ◽  
Distance Transport ◽  
Macroscopic Charcoal

Macroscopic charcoal records from wetland sediment cores are used to reconstruct long-term records of fire frequency. A central premise for the use of this tool is that macroscopic charcoal (>125 μm) represents local fires involving local vegetation. Several records reveal that there may often be exceptions to these guidelines. Previous studies have shown that particles larger than 1 cm long can travel at least 20 km from the location of a fire. We present observations of unprecedented long-distance transport of large (⩽5 cm long) charcoal particles at least 50 km from a fire west of Sydney, Australia. Factors that contribute to long-distance transport of large charcoal particles are fire intensity, upper level wind speed and landscape topography. The fires west of Sydney were large and intense, upper level (~10 km) winds exceeded 90 km h-1, and the topography east of the fire was flat or undulating. Smoke plumes from intense fires like this can reach an altitude of at least 15 km. Charcoal morphology also contributed to long-distance transport in this case. Eucalyptus trees can produce large quantities of aerodynamically efficient particles; from paper thin, smooth, decorticating bark and large sclerophyllous leaves. The presence of large macroscopic charcoal particles in wetland sediments does not automatically indicate local fires and could result from distant, large, intense fires. Large, intense fires can occur in Australia, the grasslands of Kazakhstan, Namibia, the Sahel and Patagonia. High intensity fires also occur in the forested areas of the western United States and Boreal North America. Fires in these regions could result in long-distance transport of large macroscopic charcoal particles under the right circumstances. Local charcoal flux studies are therefore critical for the interpretation of macroscopic charcoal records. We cannot rely on information from areas with different fire regimes, fire intensities or vegetation types.

How do weather and terrain contribute to firefighter entrapments in Australia?

2018 ◽  
Vol 27 (2) ◽  
pp. 85 ◽  
Author(s):  
Sebastien Lahaye ◽  
Jason Sharples ◽  
Stuart Matthews ◽  
Simon Heemstra ◽  
Owen Price ◽  
...  
Keyword(s):  
Weather Conditions ◽  
Weather Type ◽  
Clear Understanding ◽  
Fire Propagation ◽  
Adverse Weather Conditions ◽  
Adverse Weather ◽  
Large Fires ◽  
Strong Winds ◽  
Steep Slopes ◽  
Main Factor

Adverse weather conditions and topographic influences are suspected to be responsible for most entrapments of firefighters in Australia. A lack of temporally and spatially coherent set of data however, hinders a clear understanding of the contribution of each weather type or terrain driver on these events. We investigate coronial inquiries and internal fire agencies reports across several Australian states from 1980 to 2017 and retrieve 45 entrapments. A first analysis reveals that most entrapments happen during large fires and that the number of deaths has decreased over the last few decades. Comparing the meteorological and topographical conditions of the entrapments with the conditions of a reference set of fires without entrapment, we build a linear regression model that identifies the main contributors to firefighter entrapment. A change in wind direction, which was associated with 42% of the incidents examined, is the main factor contributing to entrapments. Interaction between strong winds and steep slopes also influences the likelihood of entrapment and suggests that dynamic fire behaviours may also play important roles. As further details of this relationship between dynamic fire propagation and firefighter entrapment is now required, the understanding of weather and terrain contribution is a first step to produce comprehensive safety guidance.

Study on P2P Service Bearer Method for Passive Optical Network for Long Distance and Wide Access

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Yan Wang ◽  
Shangya Han ◽  
Panke Qin ◽  
Yaping Li ◽  
Yanmei Shen
Keyword(s):  
Simulation Analysis ◽  
Optical Network ◽  
Passive Optical Network ◽  
Data Traffic ◽  
Core Network ◽  
Long Distance ◽  
Optical Line Terminal ◽  
Optical Line ◽  
Wide Access ◽  
P2p Service

AbstractFor the effective bearer of P2P-type services, a P2P service bearer reorientation method for passive optical network for long-distance wide access based on P2P protocol message and wire-speed message identification is proposed. However, the reorientation method still has the possibility of relocation failure, so it is modified – that is, an improved P2P service bearer reorientation method based on optical line terminal (OLT) and optical network unit (ONU) cooperation. And the tool NS2 is used for network simulation analysis. Through simulation analysis, it is verified that the modified reorientation method improves the data traffic burden at the core network and at the OLT.

Alpine and Subalpine Wetland Vegetation on the Bogong High Plains, South-eastern Australia

1999 ◽  
Vol 47 (2) ◽  
pp. 165 ◽  
Author(s):  
C.-H. Wahren ◽  
R. J. Williams ◽  
W. A. Papst
Keyword(s):  
Soil Depth ◽  
Vegetation Type ◽  
Soil Surface ◽  
Wetland Vegetation ◽  
High Plains ◽  
Composition And Structure ◽  
Eastern Australia ◽  
Drainage Channels ◽  
Floristic Variation ◽  
Steep Slopes

The botanical composition and structure of wetland vegetation from seven sites in the alpine and subalpine tracts of the Bogong High Plains was sampled in 1995 and 1996. Sites were in the vicinity of Mts Nelse, Cope and Fainter. Sampling was based on contiguous 1-m2 quadrats along transects 20−70 m long across each wetland. Samples were ordinated using non-metric multidimensional scaling (NMDS). Floristic variation was assessed both within selected individual wetlands, and between wetlands from different regions. The relationship between the ordinations and environmental variables such as soil surface texture, soil depth and the amount of bare ground was tested by fitting vectors. Three dominant vegetation assemblages were identified. Closed heath, of hygrophyllous, scleromorphic shrubs such as Richea continentis and Baeckea gunniana, the rush Empodisma minus and the moss Sphagnum cristatum occurred on the deeper peats. Low open heath of Epacris glacialis and Danthonia nivicola occurred on shallow peats. Herbfields of Caltha introloba and Oreobolus pumilio occurred on stony pavements in two different physiographic situations&horbar;on relatively steep slopes (10−20°) at the head of wetlands, and on flat ground (slope < 2°), below the head of wetlands. The pavements on the steeper sites appeared to be associated with periglacial features such as solifluction lobes and terraces. Those on the flatter ground appeared to have been derived more recently. Wetlands in the Mt Cope region consisted of closed heath, low open heath and pavement herbfield in various proportions. Wetlands on Mt Fainter, which are subject to heavy trampling by cattle, were in a degraded condition, with a low cover of major hygrophyllous mosses and shrubs, and a high cover of introduced species. Long-ungrazed wetlands in a 50-year exclosure at Rocky Valley had high cover of closed heath, no pavements, numerous ponds and virtually no entrenched drainage channels or exposed peat. The Caltha herbfields are significant features nationally, both floristically and geomorphologically. Alpine and subalpine wetlands have been listed under the Victorian Flora and Fauna Guarantee Act 1988, and continued grazing by cattle is not compatible with the conservation objectives for this alpine vegetation type.

scholarly journals Controlling Shipping Along the North European Trade Axis

1971 ◽  
Vol 24 (4) ◽  
pp. 553-556
Author(s):  
D. J. Lindsay
Keyword(s):  
Weather Conditions ◽  
North Coast ◽  
Baltic Basin ◽  
Long Distance ◽  
The North ◽  
Large Numbers ◽  
Straight Line ◽  
European Trade ◽  
Trade Route ◽  
The Baltic

By the North European Trade Axis is meant the trade route from Ushant and Land's End, up the English Channel, through the Dover Strait fanning out to serve eastern England, the north coast of continental Europe and leading to the Baltic Basin. Recent events in this area have left a feeling that some form of tightening of control is not only desirable, but is rapidly becoming imperative. There is a basic conflict between the two forms of shipping using the area: the local users who use the area more or less constantly, and the long-distance traders, usually much larger, which arrive in the area for a brief stay after a prolonged period at sea, which has usually been in good weather conditions. Frequently these latter ships have a very poor notion of the hornet's nest into which they are steaming when they arrive. The net result is all too often the same: the local users, with familiarity breeding contempt, wander about as they see fit, with scant regard for routing or the regulations; all too often the big ships arrive from sea with navigating staffs who are too confused, sometimes too ignorant—and sometimes too terrified—to do much more than blunder forward in a straight line hoping for the best. Quite obviously this is not a total picture, and there are large numbers of ships which navigate perfectly competently, but the minority of those which do not seem to be rising rapidly, and show every sign of continuing to increase.

scholarly journals An Advanced Numerical Trajectory Model Tracks a Corn Earworm Moth Migration Event in Texas, USA

Insects ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 115 ◽  
Author(s):  
Qiu-Lin Wu ◽  
Gao Hu ◽  
John Westbrook ◽  
Gregory Sword ◽  
Bao-Ping Zhai
Keyword(s):  
Helicoverpa Zea ◽  
Wrf Model ◽  
Weather Conditions ◽  
Computational Design ◽  
Corn Earworm ◽  
Long Distance ◽  
Hysplit Model ◽  
Trajectory Model ◽  
Trajectory Simulation ◽  
Migration Event

Many methods for trajectory simulation, such as Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), have been developed over the past several decades and contributed greatly to our knowledge in insect migratory movement. To improve the accuracy of trajectory simulation, we developed a new numerical trajectory model, in which the self-powered flight behaviors of insects are considered and trajectory calculation is driven by high spatio-temporal resolution weather conditions simulated by the Weather Research and Forecasting (WRF) model. However, a rigorous evaluation of the accuracy of different trajectory models on simulated long-distance migration is lacking. Hence, in this study our trajectory model was evaluated by a migration event of the corn earworm moth, Helicoverpa zea, in Texas, USA on 20–22 March 1995. The results indicate that the simulated migration trajectories are in good agreement with occurrences of all pollen-marked male H. zea immigrants monitored in pheromone traps. Statistical comparisons in the present study suggest that our model performed better than the popularly-used HYSPLIT model in simulating migration trajectories of H. zea. This study also shows the importance of high-resolution atmospheric data and a full understanding of migration behaviors to the computational design of models that simulate migration trajectories of highly-flying insects.

scholarly journals The millimeter frequency range as a perspective for 5G networks

2019 ◽  
Vol 6 ◽  
pp. 161-170
Author(s):  
Rosen Pasarelski
Keyword(s):  
Mobile Communications ◽  
Spectrum Sharing ◽  
New Technology ◽  
Weather Conditions ◽  
5G Networks ◽  
Frequency Range ◽  
Long Distance ◽  
Data Rates ◽  
Bad Weather ◽  
4G Cellular Networks

The currently widely used 4G cellular networks face many challenges. The growing demand for high-resolution mobile multimedia applications is bringing these networks to their practical limits. 5G networks, the next generation of wireless communications, are standardized to ease the burden on current infrastructure by offering significantly higher data rates through increased channel bandwidth. Given the lack of accessible frequencies traditionally used for mobile communications, millimeter bandwidths (mmWave) are quite a challenging alternative. This technology is a cornerstone of upcoming 5G networks, allowing faster data speeds and much higher bandwidth than ever before, but not every 5G network will necessarily use this frequency band, at least not all the time. As with any new technology, there are unavoidable problems that need to be overcome. The purpose of the research and analysis in this article is to systematize issues and solutions related to the potential problems of spectrum sharing in mmWave frequency range, its suitability for long-distance communications, indoors, in bad weather conditions, as well as biological aspects, and relevant conclusions have been done to meet these challenges.

Xanthomonas cassavae. [Descriptions of Fungi and Bacteria].

2000 ◽  
Author(s):  
G. S. Saddler
Keyword(s):  
Geographical Distribution ◽  
Systemic Infection ◽  
Climatic Conditions ◽  
Euphorbia Pulcherrima ◽  
Disease Development ◽  
Long Distance ◽  
Green Point ◽  
Leaf Spots ◽  
Strong Winds ◽  
Dark Green

Abstract A description is provided for Xanthomonas cassavae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Manihot esculenta (Euphorbiaceae); by artificial inoculation: Euphorbia pulcherrima (Euphorbiaceae). DISEASE: Cassava leaf spot or bacterial necrosis. Angular leaf spots extend along veins but generally do not develop into blight. Spots age, turn dark brown and are surrounded by a yellow halo. Exudate is frequently produced. On stems, dark green point lesions develop slowly up to 1 cm diam. Lytic pockets generally develop under lesions in the cortex. Lateral extension can lead to girdling and tip dieback. Secondary colonization by Colletotrichum gloeosporioides[Glomerella cingulata] is frequently observed. Systemic infection and vascular browning are absent or very restricted. Entry into the host is through natural openings (stomata) or epidermal wounds, which can be caused (especially on the stem) by sand particles or small grains of gravel thrown up by the strong winds which precede the first rains. The optimum temperature for disease development is 25°C. Disease mainly occurs above altitudes of 800 m. There is evidence that disease severity is linked to poor plant nutrition. GEOGRAPHICAL DISTRIBUTION: AFRICA: Burundi, Congo Democratic Republic, Kenya, Malawi, Niger, Rwanda, Tanzania, Uganda, Zaire. SOUTH AMERICA: Colombia. TRANSMISSION: Long distance spread is restricted. Symptomless cuttings taken from diseased plants were unable to demonstrate propagation. Rapid disease development under favourable climatic conditions suggests a symptomless epiphytic phase on the host itself or on a plant other than cassava. In the field, dispersal is by wind and rain.

Meteorological Problems in Forecasting Mountain Waves*

1954 ◽  
Vol 35 (8) ◽  
pp. 363-371 ◽  
Author(s):  
DeVer Colson
Keyword(s):  
Static Stability ◽  
Mountain Range ◽  
Mountain Wave ◽  
Mountain Waves ◽  
Wave Development ◽  
Strong Winds ◽  
Wind Shears ◽  
Upper Level ◽  
Meteorological Problems ◽  
Meteorological Phenomenon

The standing-wave development to the lee of prominent mountain ridges presents not only an interesting meteorological phenomenon but also a definite hazard to certain aircraft operations. An analysis of the mountain-wave observations in the Sierras indicates the presence of strong winds normal to the mountain range as well as large vertical wind shears; and an inversion or at least a stable layer near the level of the mountain crest. Changes in the pressure and temperature patterns at both the surface and 500-mb level are shown for two examples of more intense wave developments. Also, mean surface and upper-level pressure and temperature patterns are shown for the strong-wave days. The association between these mean patterns and surface frontal movements, upper-level troughs, strong temperature gradients, and the jet stream are discussed. An example of the effect of wind shear and static stability is shown using equations and methods developed by Scorer. Data on the occurrence of mountain-wave activity in other mountainous areas of the West are now being collected. Two examples of these results are shown.

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