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The Haines index (HI) is a fire-weather index that is widely used as an indicator of the potential for dry, low-static-stability air in the lower atmosphere to contribute to erratic fire behavior or large fire growth. This study e...
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The Haines index (HI) is a fire-weather index that is widely used as an indicator of the potential for dry, low-static-stability air in the lower atmosphere to contribute to erratic fire behavior or large fire growth. This study examines the interannual variability of HI over North America and its relationship to indicators of large-scale circulation anomalies. The results show that the first three HI empirical orthogonal function modes are related respectively to El Nino-Southern Oscillation (ENSO), the Arctic Oscillation (AO), and the interdecadal sea surface temperature variation over the tropical Pacific Ocean. During the negative ENSO phase, an anomalous ridge (trough) is evident over the western (eastern) United States, with warm/dry weather and more days with high HI values in the western and southeastern United States. During the negative phase of the AO, an anomalous trough is found over the western United States, with wet/cool weather and fewer days with high HI, while an anomalous ridge occurs over the southern United States-northern Mexico, with an increase in the number of days with high HI. After the early 1990s, the subtropical high over the eastern Pacific Ocean and the Bermuda high were strengthened by a wave train that was excited over the tropical western Pacific Ocean and resulted in warm/dry conditions over the southwestern United States and western Mexico and wet weather in the southeastern United States. The above conditions are reversed during the positive phase of ENSO and AO and before the early 1990s.
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This paper reports on the development and validation of a new, global, burnt area product. Burnt areas are reported at a resolution of 1 km for seven fire years (2000 to 2007). A modified version of a Global Burnt Area (GBA) 2000 ...
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This paper reports on the development and validation of a new, global, burnt area product. Burnt areas are reported at a resolution of 1 km for seven fire years (2000 to 2007). A modified version of a Global Burnt Area (GBA) 2000 algorithm is used to compute global burnt area. The total area burnt each year (2000-2007) is estimated to be between 3.5 million km 2 and 4.5 million km(2). The total amount of vegetation burnt by cover type according to the Global Land Cover (GLC) 2000 product is reported. Validation was undertaken using 72 Landsat TM scenes was undertaken. Correlation statistics between estimated burnt areas are reported for major vegetation types. The accuracy of this new global data set depends on vegetation type.
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The concept of fire regime refers to a variety of fire characteristics occurring at a given place and period of time. Understanding fire regimes is relevant to fire ecology and fire management because it provides a better understa...
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The concept of fire regime refers to a variety of fire characteristics occurring at a given place and period of time. Understanding fire regimes is relevant to fire ecology and fire management because it provides a better understanding of effects of fire as well as the potential effects of different future scenarios. Recent changes in the traditional fire regimes linked to climate and socioeconomic transformations in European Mediterranean areas have influenced fire regimes and their effects on both ecosystems and people. This paper presents a methodology for characterising fire regimes based on historical fire statistics. The analysis includes three dimensions: density, seasonality and interannual variability. The raw records were pre-processed to eliminate errors, and a principal component analysis was performed to identify the primary factors involved in the variation. A cluster analysis was then used to define the fire regimes. Approximately 38% of the spatial cells examined were found to have significant fire activity, but in spite that fires are important in these areas, fire activity showed a high interannual variability. Four fire regimes in the Spanish peninsular territory were described in terms of the density and seasonality of fire activity.Digital Object Identifier http://dx.doi.org/10.1071/WF12061
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As one of the main components of Grassland Fire Danger Index, grassland curing degree provides crucial information for determining grassland fire danger. Accurate estimates of grassland curing are critical for determining grasslan...
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As one of the main components of Grassland Fire Danger Index, grassland curing degree provides crucial information for determining grassland fire danger. Accurate estimates of grassland curing are critical for determining grassland fire risk. This research focuses on the use of Landsat 8 to estimate grassland curing. Results demonstrate that Landsat 8 observations can be used to estimate curing percentages as assessed by visual and ground sampling measurements. Grassland interannual variability for the Greater Melbourne region using Landsat 8 imagery from 2013 to 2019 is examined. Slight differences in curing times and degree are observed for sample sites surrounding Greater Melbourne due to climatic differences across the region. Precipitation is regarded as an essential variable affecting curing degree and this relationship is evident for all five sample sites. Landsat 8 curing results are compared to both visual observations and destructive sampling, the most accurate method, for accuracy assessment. At 95% confidence level, Landsat 8 estimations are no different from destructive ground sampling estimations. Overall, this study validates the use of Landsat 8 data as an effective and accurate way for grassland curing monitoring.
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We investigated the influence of climate variability on forest fire occurrence at eight sites in west central British Columbia, Canada. Forty-six local fire years affecting a single site and 16 moderate fire years affecting two or...
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We investigated the influence of climate variability on forest fire occurrence at eight sites in west central British Columbia, Canada. Forty-six local fire years affecting a single site and 16 moderate fire years affecting two or more sites were identified (1600-1900 A.D.). Existing fire history data were incorporated to identify 17 regionally synchronous fire years (fires that affected ≥3 sites). Interannual and multidecadal relationships between fire occurrence and the Palmer Drought Severity Index (PDSI), El Ni?o-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and the Pacific North American (PNA) pattern were examined, in addition to the effects of additive positive phases of ENSO and PDO. We examined multiple reconstructions of ENSO, PDO, and PNA and utilized three methodological approaches to characterize climate-fire relationships. We found that the influence of interannual climate, expressed as PDSI, increasingly synchronized the occurrence of fires when examined from local to regional scales. An association between local fires and positive antecedent moisture conditions suggests moisture-driven fine fuel development and the proximity of some sites to grasslands likely function as key determinants of local-scale fire activity. The relationships between regional fires and ENSO, PDO, and PNA suggest that large-scale patterns of climate variability exert a weak and/or inconsistent influence over fire activity in west central British Columbia between 1700 and 1900 A.D. Although inconsistent among reconstructions of climate patterns, we identified a significant relationship between regional fires and large-scale climate patterns when ENSO and PDO were both in positive phases.
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Within the last few decades, forest fire in Indonesia tends to intensify greatly with the largest event occurred in 1997-1998. Borneo (Kalimantan) is one of the islands in Indonesia which is largely affected by forest fire. In thi...
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Within the last few decades, forest fire in Indonesia tends to intensify greatly with the largest event occurred in 1997-1998. Borneo (Kalimantan) is one of the islands in Indonesia which is largely affected by forest fire. In this study, a modified Lund Potsdam Jena Dynamic Global Vegetation Model (LPJ-DGVM) is used to simulate the effect of interannual climate variability and land cover type to forest fire occurrence especially in tropical area. Two interannual climate variability indices are included into the model: MEI and DMI which represents ENSO and IOD phenomena, respectively. In study case of West Kalimantan, simulation of hotspot intensity and distribution from 2002 to 2004 shows relatively good results compared to the data. Simulation of 3 schemes without considering interannual climate variability show index of agreement of 0.389, 0.602 and 0.744, while simulation of 3 schemes with considering interannual climate variability show index of agreement of 0.761, 0.755 and 0.761. This study suggests that forest fire prediction using process-based model which includes the factors of climatology, land cover and interannual climate variability might be useful for regional future forest management to rninimize forest loss due to forest fire, especially in tropical area such as Borneo Island.
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Fires across the Arctic-boreal zone (ABZ) play an important role in the boreal forest succession, permafrost thaw, and the regional and global carbon cycle and climate. These fires occur mainly in summer with large interannual var...
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Fires across the Arctic-boreal zone (ABZ) play an important role in the boreal forest succession, permafrost thaw, and the regional and global carbon cycle and climate. These fires occur mainly in summer with large interannual variability. Previous studies primarily focused on the impacts of local surface climate and tropical El Nino-Southern Oscillation (ENSO). This study, for the first time, comprehensively investigates the influence of summer leading large-scale atmospheric teleconnection patterns in the Northern Hemisphere extra-tropics on interannual variability of ABZ fires. We use correlation and regression analysis of 1997-2019 multiple satellite-based products of burned area and observed/reanalyzed climate data. Results show that eight leading teleconnection patterns significandy affect 63 ± 2 % of burned areas across the ABZ. Western North America is affected by the East Pacific/North Pacific pattern (EP/NP) and the West Pacific pattern (WP); boreal Europe by the Scandinavia pattern (SCA); eastern North America, western and central Siberia, and southeast-ern Siberia by the North Atlantic Oscillation (NAO); and eastern Siberia /Russian Far East by the East Atlantic pattern (EA). NAO/EA induces lower-tropospheric drier northwesterly/northerly airflow passing through the east of boreal North America/Eurasia, which decreases surface relative humidity. Other teleconnections trigger a high-pressure anomaly, forcing downward motion that suppresses cloud formation and increases solar radiation reaching the ground to warm the surface air as well as brings drier air downward to reduce surface relative humidity. The drier and/or warmer surface air can decrease fuel wetness and thus increase burned area. Our study highlights the important role of the extra-tropical teleconnection patterns on ABZ fires, which is much stronger than ENSO that was thought to control interannual variability of global fires. It also establishes a theoretical foundation for ABZ fire prediction based on extra-tropical teleconnections, and has the potential to facilitate ABZ fire prediction and management.
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Precipitation variability has been predicted to increase in a global warmer climate, and is expected to greatly affect plant growth, interspecies interactions, plant community composition, and other ecosystem processes. Although p...
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Precipitation variability has been predicted to increase in a global warmer climate, and is expected to greatly affect plant growth, interspecies interactions, plant community composition, and other ecosystem processes. Although previous studies have investigated the effect of intra-annual rainfall variability on plant growth and ecosystem dynamics, the impacts of interannual rainfall variability remain understudied. This paper uses satellite data and develops a new mechanistic model to investigate the response of tree-grass composition to increasing interannual rainfall variability in arid to sub-humid ecosystems along the Kalahari Transect in Southern Africa. Both satellite data and model results show that increasing interannual rainfall fluctuations favor deep-rooted trees over shallow-rooted grasses in drier environments (that is, mean annual rainfall, MAP < 900-1000 mm) but favor grasses over trees in wetter environments (that is, MAP > 900-1000 mm). Trees have a competitive advantage over grasses in dry environments because their generally deeper root systems allow them to have exclusive access to the increased deep soil water resources expected to occur in wet years as a result of the stronger interannual rainfall fluctuations. In relatively wet environments, grasses are favored because of their high growth rate that allows them to take advantage of the window of opportunity existing in years with above average precipitation and thus increase fire-induced tree mortality. Thus, under increasing interannual rainfall fluctuations both direct effects on soil water availability and indirect effects mediated by tree-grass interactions and fire dynamics are expected to play an important role in determining changes in plant community composition.
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Precipitation variability has been predicted to increase in a global warmer climate, and is expected to greatly affect plant growth, interspecies interactions, plant community composition, and other ecosystem processes. Although p...
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Precipitation variability has been predicted to increase in a global warmer climate, and is expected to greatly affect plant growth, interspecies interactions, plant community composition, and other ecosystem processes. Although previous studies have investigated the effect of intra-annual rainfall variability on plant growth and ecosystem dynamics, the impacts of interannual rainfall variability remain understudied. This paper uses satellite data and develops a new mechanistic model to investigate the response of tree-grass composition to increasing interannual rainfall variability in arid to sub-humid ecosystems along the Kalahari Transect in Southern Africa. Both satellite data and model results show that increasing interannual rainfall fluctuations favor deep-rooted trees over shallow-rooted grasses in drier environments (that is, mean annual rainfall, MAP < 900-1000 mm) but favor grasses over trees in wetter environments (that is, MAP > 900-1000 mm). Trees have a competitive advantage over grasses in dry environments because their generally deeper root systems allow them to have exclusive access to the increased deep soil water resources expected to occur in wet years as a result of the stronger interannual rainfall fluctuations. In relatively wet environments, grasses are favored because of their high growth rate that allows them to take advantage of the window of opportunity existing in years with above average precipitation and thus increase fire-induced tree mortality. Thus, under increasing interannual rainfall fluctuations both direct effects on soil water availability and indirect effects mediated by tree-grass interactions and fire dynamics are expected to play an important role in determining changes in plant community composition.
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In many regions of the world, fires are an important and highly variable source of air pollutant emissions, and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric c...
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In many regions of the world, fires are an important and highly variable source of air pollutant emissions, and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric composition. This paper describes the 41-year inventory of vegetation fire emissions constructed for the Reanalysis of the Tropospheric chemical composition over the past 40 years project (RETRO), a global modeling study to investigate the trends and variability of tropospheric ozone and other air pollutants over the past decades. It is the first attempt to construct a global emissions data set with monthly time resolution over such a long period. The inventory is based on a literature review, on estimates from different satellite products, and on a numerical model with a semiphysical approach to simulate fire occurrence and fire spread. Burned areas, carbon consumption, and total carbon release are estimated for 13 continental-scale regions, including explicit treatment of some major burning events such as Indonesia in 1997 and 1998. Global carbon emissions from this inventory range from 1410 to 3140 Tg C/a with the minimum and maximum occurring in 1974 and 1992, respectively (mean of 2078 Tg C/a). Emissions of other species are also reported (mean CO of 330 Tg/a, NOx of 4.6 Tg N/a, CH2O of 3.9 Tg/a, CH4 of 15.4 Tg/a, BC of 2.2 Tg/a, OC of 17.6 Tg/a, SO2 of 2.2 Tg/a). The uncertainties of these estimates remain high even for later years where satellite data products are available. Future versions of this inventory may benefit from ongoing analysis of burned areas from satellite data going back to 1982.
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