scholarly journals Relationships of Fire and Precipitation Regimes in Temperate Forests of the Eastern United States

2012 ◽  
Vol 16 (11) ◽  
pp. 1-15 ◽  
Author(s):  
Charles W. Lafon ◽  
Steven M. Quiring
Keyword(s):  
United States ◽  
Daily Precipitation ◽  
Precipitation Variability ◽  
Annual Precipitation ◽  
Moisture Regime ◽  
Fire Occurrence ◽  
Climate Variables ◽  
Eastern United States ◽  
Fire Activity ◽  
The Relationship

Abstract Fire affects virtually all terrestrial ecosystems but occurs more commonly in some than in others. This paper investigates how climate, specifically the moisture regime, influences the flammability of different landscapes in the eastern United States. A previous study of spatial differences in fire regimes across the central Appalachian Mountains suggested that intra-annual precipitation variability influences fire occurrence more strongly than does total annual precipitation. The results presented here support that conclusion. The relationship of fire occurrence to moisture regime is also considered for the entire eastern United States. To do so, mean annual wildfire density and mean annual area burned were calculated for 34 national forests and parks representing the major vegetation and climatic conditions throughout the eastern forests. The relationship between fire activity and two climate variables was analyzed: mean annual moisture balance [precipitation P − potential evapotranspiration (PET)] and daily precipitation variability (coefficient of variability for daily precipitation). Fire activity is related to both climate variables but displays a stronger relationship with precipitation variability. The southeastern United States is particularly noteworthy for its high wildfire activity, which is associated with a warm, humid climate and a variable precipitation regime, which promote heavy fuel production and rapid drying of fuels.

scholarly journals ENSO and Wintertime Extreme Precipitation Events over the Contiguous United States

2008 ◽  
Vol 21 (1) ◽  
pp. 22-39 ◽  
Author(s):  
Siegfried D. Schubert ◽  
Yehui Chang ◽  
Max J. Suarez ◽  
Philip J. Pegion
Keyword(s):  
United States ◽  
West Coast ◽  
Extreme Precipitation ◽  
East Coast ◽  
Daily Precipitation ◽  
Precipitation Variability ◽  
The West ◽  
Extreme Precipitation Events ◽  
The Impact ◽  
Precipitation Events

Abstract In this study the authors examine the impact of El Niño–Southern Oscillation (ENSO) on precipitation events over the continental United States using 49 winters (1949/50–1997/98) of daily precipitation observations and NCEP–NCAR reanalyses. The results are compared with those from an ensemble of nine atmospheric general circulation model (AGCM) simulations forced with observed SST for the same time period. Empirical orthogonal functions (EOFs) of the daily precipitation fields together with compositing techniques are used to identify and characterize the weather systems that dominate the winter precipitation variability. The time series of the principal components (PCs) associated with the leading EOFs are analyzed using generalized extreme value (GEV) distributions to quantify the impact of ENSO on the intensity of extreme precipitation events. The six leading EOFs of the observations are associated with major winter storm systems and account for more than 50% of the daily precipitation variability along the West Coast and over much of the eastern part of the country. Two of the leading EOFs (designated GC for Gulf Coast and EC for East Coast) together represent cyclones that develop in the Gulf of Mexico and occasionally move and/or redevelop along the East Coast producing large amounts of precipitation over much of the southern and eastern United States. Three of the leading EOFs represent storms that hit different sections of the West Coast (designated SW for Southwest coast, WC for the central West Coast, and NW for northwest coast), while another represents storms that affect the Midwest (designated by MW). The winter maxima of several of the leading PCs are significantly impacted by ENSO such that extreme GC, EC, and SW storms that occur on average only once every 20 years (20-yr storms) would occur on average in half that time under sustained El Niño conditions. In contrast, under La Niña conditions, 20-yr GC and EC storms would occur on average about once in 30 years, while there is little impact of La Niña on the intensity of the SW storms. The leading EOFs from the model simulations and their connections to ENSO are for the most part quite realistic. The model, in particular, does very well in simulating the impact of ENSO on the intensity of EC and GC storms. The main model discrepancies are the lack of SW storms and an overall underestimate of the daily precipitation variance.

Impediments to prescribed fire across agency, landscape and manager: an example from northern California

2012 ◽  
Vol 21 (3) ◽  
pp. 210 ◽  
Author(s):  
Lenya N. Quinn-Davidson ◽  
J. Morgan Varner
Keyword(s):  
United States ◽  
Prescribed Fire ◽  
Prescribed Burning ◽  
Social Constraints ◽  
Northern California ◽  
Eastern United States ◽  
Environmental Laws ◽  
The Public ◽  
Management Objectives ◽  
Fire Activity

Though the need for prescribed fire is widely recognised, its use remains subject to a range of operational and social constraints. Research has focussed on identifying these constraints, yet past efforts have focussed disproportionately on single agencies and geographic regions. We examined constraints on prescribed fire by surveying a wide variety of organisations (including six state and federal agencies and several tribes, non-governmental organisations and timber companies) in northern California, a fire-prone region of the western United States. Across the region, prescribed burning annually covered only 38% of the area needed to fulfil land-management objectives, and 66% of managers indicated dissatisfaction with levels of prescribed fire activity. The highest-ranked impediments were narrow burn window, regulations, lack of adequate personnel and environmental laws. Impediment ratings differed among entities, with legal and social impediments of greater concern in the private sector than in the public, and economic impediments of greater concern in the state and private sectors than in the federal. Comparisons with the south-eastern United States, where similar research has taken place, point to important regional constraints on prescribed fire activity. These findings suggest further need for research spanning geographic and ownership boundaries, as prescribed fire impediments can vary by context.

The Relationship between the North Atlantic Oscillation and High-Wind Observations Across the Eastern United States 

2021 ◽  
Author(s):  
Sylvia Stinnett ◽  
Joshua Durkee ◽  
Joshua Gilliland ◽  
Victoria Murley ◽  
Alan Black ◽  
...  
Keyword(s):  
United States ◽  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Eastern United States ◽  
High Wind ◽  
The North ◽  
The North Atlantic ◽  
Wind Events ◽  
The North Atlantic Oscillation ◽  
The Relationship

<p>The North Atlantic Oscillation (NAO) is a high-frequency oscillation that has known influences on the climatology of weather patterns across the eastern United States. This study explores the relationship between the daily North Atlantic Oscillation index with observed high-wind events from 391 first-order weather stations across the eastern U.S. from 1973-2015. These events were determined following typical National Weather Service high-wind criteria: sustained winds of at least 18 m•s-1 for at least 1 hour or a wind gust of at least 26 m•s-1 for any duration. Since research literature shows high-wind events are often connected to parent mid-latitude cyclone tracks, and since the NAO has been shown to influence these storm tracks, it is hypothesized that changes in NAO phases are connected to spatial shifts and frequencies in high-wind observations. Initial results show a preferred southwesterly direction during each NAO phase. Variance in high-wind directions appears to increase (decrease) during negative (positive) NAO phases. Further, the greatest spatial difference in the mean center of high-wind observations was between positive and negative NAO phases. Overall, these preliminary findings indicate changes in high-wind observations may be linked to NAO phases.</p>

A multi-resolution analysis of historical and future precipitation variability across the western United States 

2021 ◽  
Author(s):  
Nels Bjarke ◽  
Ben Livneh ◽  
Joseph Barsugli ◽  
Xiao Wei Quan ◽  
Martin Hoerling
Keyword(s):  
United States ◽  
Heavy Precipitation ◽  
Precipitation Variability ◽  
Western United States ◽  
Annual Precipitation ◽  
Historical Period ◽  
Data Set ◽  
Future Projections ◽  
Western Us ◽  
Precipitation Events

<p>Evaluating the future of surface water availability in the western United States requires a robust analysis of the projected trends in precipitation variability within the new generation of global climate model (GCM) simulations. To understand the reliability of future projections, we first construct a historical baseline (1950-2014) of the precipitation climatology and  contribution of heavy precipitation events to the total annual precipitation from an ensemble of in-situ (Global Historical Climatology Network (GHCN)) and gridded precipitation products (Abatzoglou, 2013; Livneh et al., 2015; Newman et al., 2015). This historical baseline is used to evaluate the representation of precipitation variability during the historical period of GCM simulations from the CMIP6 HighResMIP and ScenarioMIP ensembles as well as the multi-resolution, factual-counterfactual ensemble of CAM5 simulations. We frame our analysis in the context of water resources by using a collection of large basins across the western US to demonstrate that the role of GCM resolution in the representation of precipitation variability is highly dependent on regional differences in topographical controls and dominant climatological drivers of precipitation. In most regions, we find that the highest-resolution GCM simulations (25-50 km) portray realistic occurrences of heavy precipitation events when compared to gridded historical precipitation at the same spatial resolution, whereas coarser GCM simulations (100-200 km) tend to distribute precipitation more evenly throughout the year than expected. When compared to the historical period (1950-2014), future projections (2014-2050) from both HighResMIP and ScenarioMIP ensembles produce more variable precipitation with a higher fraction of the annual precipitation falling in heavy precipitation events.  Furthermore, we explore methods for constraining uncertainty in the projection of future precipitation variability across the Western US using a statistical assessment of the historical GCM simulations compared to the historical baseline.</p><p>References</p><p>Abatzoglou, J. T. (2013). Development of gridded surface meteorological data for ecological applications and modelling. International Journal of Climatology, 33(1), 121–131. https://doi.org/10.1002/joc.3413</p><p>Livneh, B., Bohn, T. J., Pierce, D. W., Munoz-Arriola, F., Nijssen, B., Vose, R., Cayan, D. R., & Brekke, L. (2015). A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013. Scientific Data, 2(1), 1–12. https://doi.org/10.1038/sdata.2015.42</p><p>Newman, A. J., Clark, M. P., Sampson, K., Wood, A., Hay, L. E., Bock, A., Viger, R. J., Blodgett, D., Brekke, L., Arnold, J. R., Hopson, T., & Duan, Q. (2015). Development of a large-sample watershed-scale hydrometeorological data set for the contiguous USA: Data set characteristics and assessment of regional variability in hydrologic model performance. Hydrology and Earth System Sciences, 19(1), 209–223. https://doi.org/10.5194/hess-19-209-2015</p>

scholarly journals Daily Precipitation and Tropical Moisture Exports across the Eastern United States: An Application of Archetypal Analysis to Identify Spatiotemporal Structure

2015 ◽  
Vol 28 (21) ◽  
pp. 8585-8602 ◽  
Author(s):  
Scott Steinschneider ◽  
Upmanu Lall
Keyword(s):  
North Atlantic ◽  
Daily Precipitation ◽  
Precipitation Variability ◽  
Sea Surface ◽  
Spatiotemporal Variability ◽  
Eof Analysis ◽  
Eastern United States ◽  
Archetypal Analysis ◽  
The North ◽  
Tropical Moisture

Abstract This study examines the spatiotemporal variability of two sets of daily precipitation from ERA-Interim across the eastern United States between 1979 and 2013: 1) total precipitation and 2) precipitation originating from tropical moisture exports (TMEs), which have been linked to extremes of midlatitude precipitation. Archetypal analysis (AA) is introduced as a new method to decompose and characterize structures within the spatiotemporal climate data. AA is uniquely suited to identify extremal patterns and is a complementary method to empirical orthogonal function (EOF) analysis. The authors provide a brief comparison between AA and EOF analysis and then examine the spatiotemporal variability, circulation anomalies, and sea surface temperature teleconnections associated with the archetypes of the two precipitation variables. Markovian structure, seasonal variability, and interannual trends in archetype occurrence are explored using nonparametric generalized linear models (GLMs). Results show that the modes of precipitation variability and their associated teleconnections are very similar between total and TME precipitation, suggesting that TMEs can help explain prevailing modes of total precipitation variability. Both total and TME precipitation shift longitudinally conditional on the phase of the Pacific decadal oscillation (PDO) and sea surface temperatures in the North Atlantic, and they are inhibited during strong, negative PDO and positive Atlantic multidecadal oscillation (AMO) regimes. The GLM analysis reveals distinct seasonal cycles and decadal trends in archetypes likely associated with the strength and position of the North Atlantic subtropical high (NASH). The study concludes with a discussion of the limitations of the analysis and other promising applications of AA.

Relationships between climate and macroscale area burned in the western United States

2013 ◽  
Vol 22 (7) ◽  
pp. 1003 ◽  
Author(s):  
John T. Abatzoglou ◽  
Crystal A. Kolden
Keyword(s):  
United States ◽  
Snow Water Equivalent ◽  
Climatic Factors ◽  
Fire Danger ◽  
Western United States ◽  
Fire Season ◽  
Drought Indices ◽  
Climate Variables ◽  
Area Burned ◽  
Fire Activity

Increased wildfire activity (e.g. number of starts, area burned, fire behaviour) across the western United States in recent decades has heightened interest in resolving climate–fire relationships. Macroscale climate–fire relationships were examined in forested and non-forested lands for eight Geographic Area Coordination Centers in the western United States, using area burned derived from the Monitoring Trends in Burn Severity dataset (1984–2010). Fire-specific biophysical variables including fire danger and water balance metrics were considered in addition to standard climate variables of monthly temperature, precipitation and drought indices to explicitly determine their optimal capacity to explain interannual variability in area burned. Biophysical variables tied to the depletion of fuel and soil moisture and prolonged periods of elevated fire-danger had stronger correlations to area burned than standard variables antecedent to or during the fire season, particularly in forested systems. Antecedent climate–fire relationships exhibited inter-region commonality with area burned in forested lands correlated with winter snow water equivalent and emergent drought in late spring. Area burned in non-forested lands correlated with moisture availability in the growing season preceding the fire year. Despite differences in the role of antecedent climate in preconditioning fuels, synchronous regional fire activity in forested and non-forested lands suggests that atmospheric conditions during the fire season unify fire activity and can compound or supersede antecedent climatic stressors. Collectively, climate–fire relationships viewed through the lens of biophysical variables provide a more direct link to fuel flammability and wildfire activity than standard climate variables, thereby narrowing the gap in incorporating top-down climatic factors between empirical and process-based fire models.

Genetic relationships in Abies (fir) of eastern United States: an electrophoretic study

1984 ◽  
Vol 62 (4) ◽  
pp. 609-616 ◽  
Author(s):  
Brian F. Jacobs ◽  
Charles R. Werth ◽  
Sheldon I. Guttman
Keyword(s):  
United States ◽  
Cluster Analysis ◽  
Genetic Relationships ◽  
Genetic Distances ◽  
Hybrid Origin ◽  
Eastern United States ◽  
Electrophoretic Study ◽  
Alternative Hypotheses ◽  
The Relationship ◽  
Cone Scale

Abies (fir) is widely considered to consist of two species in the eastern United States, A. balsamea (L.) Mill, and A. fraseri (Pursh.) Poir., distinguished by relative cone bract to subtending cone scale lengths and number of leaf hypodermal cells. Intermediate individuals have been recognized as A. balsamea var. phanerolepis Fern. An understanding of the relationship between the two putative species hinges on the interpretation of the intermediate. Two alternative hypotheses view the intermediate as either an interspecific hybrid or as an intraspecific variant. Twenty gene loci were electrophorctically analyzed in samples from 12 populations representing all three taxa. All populations shared similar complements of alleles at comparable frequencies for 13 polymorphic loci. Genetic distances among populations ranged from 0.10 to 0.0. Cluster analysis joined populations of A. fraseri with those representing A. balsamea var. phanerolepis at a distance of 0.03 and linked populations of A. balsamea with the other two taxa at 0.06. A hierarchical analysis of the three taxa, delimited by cluster analysis and bract exsertion, places A. balsamea var. phanerolepis intermediate between the two species. These data support a conspecifie status for all of eastern U.S. Abies with gene exchange between populations relatively unrestricted at last contact (≈ 10 000 years BP). Further, A. balsamea var. phenerolepis, while electrophoretically intermediate, is likely not of hybrid origin. Our results are consistent with those of recent studies which conclude that A. fraseri and A. balsamea are very closely related taxa of Pleistocene origin.

The problem of undersampling for models of archaeological occupations derived from shovel testing and its consequences for significance determinations

2020 ◽  
pp. 019769312098098
Author(s):  
Jeffrey S Alvey
Keyword(s):  
United States ◽  
Academic Research ◽  
Sampling Strategy ◽  
Ground Cover ◽  
Eastern United States ◽  
Testing Strategies ◽  
A Site ◽  
The Relationship

Archaeologists working in the Eastern United States routinely employ shovel testing as a method for site discovery and delineation in areas of dense ground cover, and as a means of collecting information on the kinds and numbers of artifacts and features present at a site. This sampling strategy is employed in the context of Section 106 compliance, as well as in academic research. This paper presents findings on the relationship between shovel-testing strategies and the accuracy and usefulness of the models of archaeological occupations that result from the information collected during shovel testing. These results demonstrate that some common approaches to shovel testing lead to faulty models that fail to accurately represent important occupational variables, thus compromising our ability to make valid significance determinations.

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