Timothy J. Brown

Climate-induced variations in global wildfire danger from 1979 to 2013

Climate strongly influences global wildfire activity, and recent wildfire surges may signal fire weather-induced pyrogeographic shifts. Here we use three daily global climate data sets and three fire danger indices to develop a simple annual metric of fire weather season length, and map spatio-temporal trends from 1979 to 2013. We show that fire weather seasons have lengthened across 29.6 million km2 (25.3%) of the Earths vegetated surface, resulting in an 18.7% increase in global mean fire weather season length. We also show a doubling (108.1% increase) of global burnable area affected by long fire weather seasons (>1.0 σ above the historical mean) and an increased global frequency of long fire weather seasons across 62.4 million km2 (53.4%) during the second half of the study period. If these fire weather changes are coupled with ignition sources and available fuel, they could markedly impact global ecosystems, societies, economies and climate.

Gulf of California Sea Surface Temperatures and the North American Monsoon: Mechanistic Implications from Observations

Abstract Perhaps the most regular and predictable weather pattern in North America is the North American (NA) or Mexican monsoon. Occurring in summer, it delivers about 35% and 45% of Arizonas and New Mexicos annual precipitation, respectively, and about 60% of northern Mexicos. While recent studies have linked strong NA monsoons to summer drought in the U.S. Midwest, the sequence of events that produce the NA monsoon remain unclear. This empirical study builds on the findings of many other studies that implicate the Gulf of California [(GOC) or simply the gulf] as the dominant moisture source for the monsoon. It examines six monsoon seasons in detail, and quantitatively relates GOC sea surface temperatures (SST) to the timing, amount, and regional extent of monsoon rainfall. This six season study is based on satellite measurements of rainfall [using the Special Sensor Microwave Imager (SSM/I)] and GOC SST at high spatial and temporal resolution. Key findings include the following. 1) Monsoon rainfall ...

Climate, Santa Ana Winds and autumn wildfires in southern California

Wildfires periodically burn large areas of chaparral and adjacent woodlands in autumn and winter in southern California. These fires often occur in conjunction with Santa Ana weather events, which combine high winds and low humidity, and tend to follow a wet winter rainy season. Because conditions fostering large fall and winter wildfires in California are the result of large-scale patterns in atmospheric circulation, the same dangerous conditions are likely to occur over a wide area at the same time. Furthermore, over a century of watershed reserve management and fire suppression have promoted fuel accumulations, helping to shape one of the most conflagration-prone environments in the world [Pyne, 1997]. Combined with a complex topography and a large human population, southern Californian ecology and climate pose a considerable physical and societal challenge to fire management.

The Use of t Values in Climatological Composite Analyses

Composite maps have been used in climatology for many years. Typically their formulation has involved identifying a group of years with similar characteristics (e.g., warm anomaly, positive height anomaly), calculating the overall mean of those years using a gridded map dataset, and finally, presenting a map of the composite means with the key spatial characteristics highlighted. This is often done for anomalies, as shown in Fig. 1 (Cayan 1996). Here, 700-mb composite height anomalies associated with April snow water equivalent are related to precipitation and temperature patterns. It is not uncommon to see composite maps given as means and with some form of statistical significance test to assess chance occurrence of the pattern. The shaded areas in Fig. 1 show those regions meeting a particular parametric significance test requirement. The use of the simple arithmetic mean in composites has at least two shortcomings. These are 1) the mean as a measure of location is not resistant to outliers, especially in small samples, and 2) it does not account for the associated variance. In order to overcome these drawbacks, we recommend a form of scaled mean (following Iglewicz 1983) for the construction of composites. This form is particularly useful for small samples, which often are used for composites. It is also useful when the data distribution is unknown, or known to be non-Gaussian. Finally, it is easy to calculate. Given a population mean m and population variance s 2 , the scaled mean has the form

Wildfire Management and Forecasting Fire Potential: The Roles of Climate Information and Social Networks in the Southwest United States

AbstractContinuing progress in the fields of meteorology, climatology, and fire ecology has enabled more proactive and risk-tolerant wildland fire management practices in the United States. Recent institutional changes have also facilitated the incorporation of more advanced climate and weather research into wildland fire management. One of the most significant changes was the creation of Predictive Services in 1998, a federal interagency group composed, in part, of meteorologists who create climate- and weather-based fire outlooks tailored to fire manager needs. Despite the numerous forecast products now available to fire managers, few studies have examined how these products have affected their practices. In this paper the authors assess how fire managers in the Southwest region of the United States perceive and incorporate different types of information into their management practices. A social network analysis demonstrates that meteorologists have become central figures in disseminating information in...

Visual Data Mining In Atmospheric Science Data

This paper discusses the use of simple visual tools to explore multivariate spatially-referenced data. It describes interactive approaches such as linked brushing, and dynamic methods such as the grand tour, applied to studying the Comprehensive Ocean-Atmosphere Data Set (COADS). This visual approach provides an alternative way to gain understanding of high-dimensional data. It also provides cross-validation and visual adjuncts to the more computationally intensive data mining techniques.

Beyond wildfire: perspectives of climate, managed fire and policy in the USA

Climate–wildfire relationships have been widely addressed by the scientific community over the last two decades; however, the role of climate in managed fire in the US (i.e. prescribed fire and wildland fire use) has not yet been addressed. We hypothesised that if climate is an important component of managed fire, the fire community would already be aware of this and using climate information in order to mitigate risks associated with managed fires. We conducted 223 surveys with fire managers to ascertain how climate information is utilised in managed-fire decision-making. We found that wildland fire use managers consider climate to be an important aspect of managed fire and use various types of climate information, but prescribed-fire managers do not generally consider climate or use climate information in their planning activities. Survey responses also indicate a lack of agency training on climate information and decision-support tools. This is partly attributed to obstacles in US fire policy that inhibit widespread utilisation of climate information. We suggest these results are indicative of a broader conflict in US wildfire policy, which does not directly address climate despite two decades of scientific research showing climate plays a key role in wildfire regimes.

Seasonal reversal of the influence of El Niño–Southern Oscillation on very large wildfire occurrence in the interior northwestern United States

Satellite-mapped fire perimeters and the multivariate El Nino–Southern Oscillation index were used to examine the impact of concurrent El Nino–Southern Oscillation (ENSO) phase on very large fire (VLF) occurrences over the intermountain northwestern United States (U.S.) from 1984 to 2012. While the warm phase of ENSO promotes drier and warmer than normal conditions across the region during winter and spring that favor widespread fire activity the following summer, a reduction in VLFs was found during the warm phase of ENSO during summer concurrent with the fire season. This paradox is primarily tied to an anomalous upper level trough over the western U.S. and positive anomalies in integrated water vapor that extend over the northwestern U.S. during summers when the warm phase of ENSO is present. Collectively, these features result in widespread increases in precipitation amount during the summer and a curtailment of periods of critically low-fuel moistures that can carry wildfire.

VRFire: an Immersive Visualization Experience for Wildfire Spread Analysis

Wildfires are a frequent summer-time concern for land managers and communities neighboring wildlands throughout the world. Computational simulations have been developed to help analyze and predict wildfire behavior, but the primary visualization of these simulations has been limited to 2-dimensional graphics images. We are currently working with wildfire research groups and those responsible for managing the control of fire and mitigation of the wildfire hazard to develop an immersive visualization and simulation application. In our visualization application, the fire spread model will be graphically illustrated on a realistically rendered terrain created from actual DEM data and satellite photography. We are working to improve and benefit tactical and strategic planning, and provide training for firefighter and public safety with our application

Wilderness Fire Management in a Changing Environment

Two major factors affecting wilderness fire regimes and their management are climate variability and surrounding land use. Patterns in climate and housing densities are expected to change dramatically in the next several decades (IPCC 2007; Theobald and Romme 2007) with important implications for fire management and policy (Dombeck et al. 2004). Successful protection and stewardship of wilderness means anticipating how these trends will affect fire regimes in the future.