Characterization of spatio-temporal patterns for various GRACE- and GLDAS-born estimates for changes of global terrestrial water storage (original) (raw)
Related papers
Aim This paper describes the characteristics of the spatio-temporal distribution of vegetation fires as detected from satellite data for the 12 months April 1992 to March 1993. Location Fires are detected daily at a spatial resolution of 1 km for all land areas of the globe. Methods From the fire location information a daily gridded product at 0.5 degrees by 0.5 degrees has been constructed. Two methods of characterizing the spatio-temporal pattern of vegetation fires are discussed. The first applies empirical orthogonal function analysis to the monthly series of gridded data. The second approach defines and extracts a number of spatial and temporal parameters from the gridded product. The descriptive parameters extracted are used in a cluster analysis in order to group cells with similar characteristics into a small number of classes. Results Using daily global satellite observations, it is possible to characterize the spatial and temporal variability in fire activity. Most of this variability is within the tropical belt, where the majority of fire activity is concentrated, nonetheless fire was also detected in temperate and boreal regions. The period in which fire occurred varied from region to region. Parameterization provided a very synthetic view of this variability facilitating regional intercomparison. Clustering identifies five classes of fire activity, each of which can be associated with particular climatic conditions, vegetation types and land-use. Main conclusions Global monitoring of vegetation fire from satellite is possible. The analysis provides a coherent, consistent and synoptic view of global fire activty with one data set. The type of information extracted can be of use in global atmospheric chemistry modelling and for studying the role of fire in relation to global change issues.
Journal of Biogeography, 2000
Aim This paper describes the characteristics of the spatio-temporal distribution of vegetation fires as detected from satellite data for the 12 months April 1992 to March 1993.Location Fires are detected daily at a spatial resolution of 1 km for all land areas of the globe.Methods From the fire location information a daily gridded product at 0.5° by 0.5° has been constructed. Two methods of characterizing the spatio-temporal pattern of vegetation fires are discussed. The first applies empirical orthogonal function analysis to the monthly series of gridded data. The second approach defines and extracts a number of spatial and temporal parameters from the gridded product. The descriptive parameters extracted are used in a cluster analysis in order to group cells with similar characteristics into a small number of classes.Results Using daily global satellite observations, it is possible to characterize the spatial and temporal variability in fire activity. Most of this variability is within the tropical belt, where the majority of fire activity is concentrated, nonetheless fire was also detected in temperate and boreal regions. The period in which fire occurred varied from region to region. Parameterization provided a very synthetic view of this variability facilitating regional intercomparison. Clustering identifies five classes of fire activity, each of which can be associated with particular climatic conditions, vegetation types and land-use.Main conclusions Global monitoring of vegetation fire from satellite is possible. The analysis provides a coherent, consistent and synoptic view of global fire activty with one data set. The type of information extracted can be of use in global atmospheric chemistry modelling and for studying the role of fire in relation to global change issues.
Journal of Geophysical Research: Biogeosciences, 2014
Fire is a critical component of the Earth system, and substantially influences land surface, climate change, and ecosystem dynamics. To accurately predict the fire regimes in the 21st century, it is essential to understand the historical fire patterns and recognize the interaction among fire, human, and environment factors. Until now, few efforts are put on the studies regarding to the long-term fire reconstruction and the attribution analysis of anthropogenic and environmental factors to fire regimes at global scale. To fill this knowledge gap, we developed a 0.5°× 0.5°data set of global burned area from 1901 to 2007 by coupling Global Fire Emission Database version 3 with a process-based fire model and conducted factorial simulation experiments to evaluate the impacts of human, climate, and atmospheric components. The average global burned area is 442 × 10 4 km 2 yr À1 during 1901-2007 and our results suggest a notable declining rate of burned area globally (1.28 × 10 4 km 2 yr À1). Burned area in tropics and extratropics exhibited a significant declining trend, with no significant trend detected at high latitudes. Factorial experiments indicated that human activities were the dominant factor in determining the declining trend of burned area in tropics and extratropics, and climate variation was the primary factor controlling the decadal variation of burned area at high latitudes. Elevated CO 2 and nitrogen deposition enhanced burned area in tropics and southern extratropics but suppressed fire occurrence at high latitudes. Rising temperature and frequent droughts are becoming increasingly important and expected to increase wildfire activity in many regions of the world.
Climate and Vegetation as Driving Factors in Global Fire Activity
Advances in Global Change Research, 2000
Global active fire distributions have been determined for a 12 month period from daily acquired, low spatial resolution satellite imagery. These distributions have been grouped into a small number of classes based on the spatial and temporal characteristics of the data. A global climatology of monthly temperature and precipitation data was used to derive warmth and moisture indices. We show how different patterns of fire activity, as represented by the fire classes, can be related to particular climate conditions. Vegetation type is also shown to be important in determining fire activity, in particular in tropical regions. Our results support the premise that fire regimes will change under changed climate conditions and the empirical approach to the investigation of the fire-climate relationship could provide a complementary tool to the physically-based climate change prediction models
Global characterization of fire activity: toward defining fire regimes from Earth observation data
Global Change Biology, 2008
There is interest in the global community on how fire regimes are changing as a function of changing demographics and climate. The ground-based data to monitor such trends in fire activity are inadequate at the global scale. Satellite observations provide a basis for such a monitoring system. In this study, a set of metrics were developed from 6 years of MODIS active fire data. The metrics were grouped into eight classes representing three axes of fire activity: density, season duration and interannual variability. These groups were compared with biophysical and human explanatory variables on a global scale. We found that more than 30% of the land surface has a significant fire frequency. The most extensive fire class exhibited high fire density, low duration and high variability and was found in boreal and tropical wet and dry environments. A high association was found between population distribution and fire persistence. Low GDP km À2 was associated with fire classes with high interannual variability and low seasonal duration. In areas with more economic resources, fires tend to be more regular and last longer. High fire duration and low interannual variability were associated with croplands, but often with low fire density. The study was constrained by the limited length of satellite data record but is a first step toward developing a comprehensive global assessment of fire regimes. However, more attention is needed by the global observing systems to provide the underpinning socio-economic observations to better quantify and analyze the human characteristics of fire regimes.
Global patterns of interannual climate-fire relationships
Global change biology, 2018
Climate shapes geographic and seasonal patterns in global fire activity by mediating vegetation composition, productivity, and desiccation in conjunction with land-use and anthropogenic factors. Yet, the degree to which climate variability affects interannual variability in burned area across Earth is less understood. Two-decades of satellite-derived burned area records across forested and non-forested areas were used to examine global interannual climate-fire relationships at ecoregion scales. Measures of fuel aridity exhibited strong positive correlations with forested burned area, with weaker relationships in climatologically drier regions. By contrast, cumulative precipitation antecedent to the fire season exhibited positive correlations to non-forested burned area, with stronger relationships in climatologically drier regions. Climate variability explained roughly one-third of the interannual variability in burned area across global ecoregions. These results highlight the impor...
Global Ecology and Biogeography, 2010
Aim In any region affected, fires exhibit a strong seasonal cycle driven by the dynamic of fuel moisture and ignition sources throughout the year. In this paper we investigate the global patterns of fire seasonality, which we relate to climatic, anthropogenic, land-cover and land-use variables.Location Global, with detailed analyses from single 1°× 1° grid cells.Methods We use a fire risk index, the Chandler burning index (CBI), as an indicator of the ‘natural’, eco-climatic fire seasonality, across all types of ecosystems. A simple metric, the middle of the fire season, is computed from both gridded CBI data and satellite-derived fire detections. We then interpret the difference between the eco-climatic and observed metrics as an indicator of the human footprint on fire seasonality.Results Deforestation, shifting cultivation, cropland production or tropical savanna fires are associated with specific timings due to land-use practices, sometimes largely decoupled from the CBI dynamics. Detailed time series from relevant locations provide comprehensive information about these practices and how they are adapted to eco-climatic conditions.Main conclusions We find a great influence of anthropogenic activities on global patterns of fire seasonality. The specificity of the main fire practices and their easy identification from global observation is a potential tool to support land-use monitoring efforts. Our results should also prove valuable in the development of a methodological approach for improving the representation of anthropogenic fire practices in dynamic global vegetation models.
Fire ecology The interactions between fire and the abiotic and biotic components of an ecosystem. Fire regime The expression of multiple fire events within a spatial and temporal domain; the type of fire, mean and variance in fire frequency, intensity, severity, season, and areal extent of a burn in an ecosystem. Fire-stimulated recruitment Seedling recruitment in the first one or two growing seasons after a burn. General circulation model (GCM) Computer models developed to simulate global climate and widely used for global climate change predictions. Prescribed burning Fires intentionally lit for management purposes. Serotiny Seeds stored on the plant with dispersal triggered by fire. Wildfires Uncontrolled wildland fires. Fire in Earth History Fire is an enormously influential disturbance over large areas of land in the modern world. Vegetation burns because the Earth's atmosphere contains sufficient oxygen (415%) to support combustion (Pyne, 2001). Oxygen started to accumulate in the atmosphere about 2 billion years ago and, since the appearance of plants in the Devonian (B400 million years ago) to provide fuel, there is an almost continuous record of fossil charcoal over the past 350 million years indicating that the atmosphere supported combustion for most of terrestrial plant evolution (Scott, 2000). Oxygen levels reached maxima in the Upper Carboniferous, about 300 million years ago (Ma), when abundant fossil charcoal indicates frequent fires. Fires were also common during the Cretaceous (135-165 Ma) when flowering plants (angiosperms) first began to spread. Fossil flowers, with fine structure beautifully preserved as charcoal, are common and widespread in Cretaceous deposits (Nixon and Crepet, 1993). At these and other times, frequent fires may have played a significant part in the ecology and evolution of paleo-ecosystems (Bowman et al., 2009). Broadleaved forest, analogous to present-day tropical and temperate forests, first became globally widespread in the Eocene (55-35 Ma) a warm wet period. Fossil evidence for fire is rare during this time but dated molecular phylogenies indicate that fires were continuing to burn in Eocene landscapes (Scott, 2000). Grasslands are the most flammable vegetation that has existed in earth history. Tropical (C4) grasslands and savannas are the most extensive flammable biomes today occupying one-fifth of the world's land surface. Though C4 grasses are ancient (30 Ma BP), the savanna biome first began to spread from the late Miocene (8 Ma). Charcoal from marine sediments increased dramatically during the past 10 Ma as fire-promoting ecosystems, including savannas, began to spread (Bowman et al., 2009). Hominids have used lightning-ignited fire for perhaps as long as 1-1.5 My but first began to ignite their own fires from 200 to 400 ka BP (Pyne, 2001). Fire was used for many reasons, such as clearing vegetation to facilitate transportation; promoting growth of edible plants in hunter-gatherer communities; and attracting animals to hunting grounds (Vale, 2002; Fig. 1). Fire was (and is) a tool used by farmers to clear new lands and to prepare sites for swidden-type farming. However, the historical impacts of human use of fire on the environment are greatly dependent on geographic area. Increases in charcoal in southeast Asia (50 ka) and Australia (60-45 ka) are coincident with the arrival of fire-using modern humans, however, charcoal records from Europe reveal that climate change, rather than changes in human use of fire, best correlates with fire activity from 70 to 10 ka (Daniau et al., 2010). Charcoal records from around the world for the past two millennia indicate little impact of humans on biomass burning until as late as the mid 1700s with an abrupt decline in burning after 1870 (Marlon et al., 2008). Thus, the area burnt by vegetation fires may be at its lowest level for the past few millennia. World Biomes and Fire Incidence Satellite imagery is beginning to reveal the vast global extent of fires. Between 1997 and 2008, the average global burnt area was 3.7 million km 2 or 2.8% of the total unglaciated land area (Giglio et al., 2010). Nearly one-third of the land surface experienced ☆ Change History: February 2016. R.E. Keane added author affiliation and four new figures, added additional text and text amendments throughout the article, and references completely updated.
Characterizing Global Fire Regimes from Satellite-Derived Products
Forests
We identified four global fire regimes based on a k-means algorithm using five variables covering the spatial, temporal and magnitude dimensions of fires, derived from 19-year long satellite burned area and active fire products. Additionally, we assessed the relation of fire regimes to forest fuels distribution. The most extensive fire regime (35% of cells having fire activity) was characterized by a long fire season, medium size fire events, small burned area, high intensity and medium variability. The next most extensive fire regime (25.6%) presented a long fire season, large fire events and the highest mean burned area, yet it showed the lowest intensity and the least variability. The third group (22.07%) presented a short fire season, the lowest burned area, with medium-low intensity, the smallest fire patches and large variability. The fourth group (17.3%) showed the largest burned area with large fire patches of moderate intensity and low variability. Fire regimes and fuel typ...