Monday, 17 November 2003
Enhancement of the National Fire Danger Rating System for the New Jersey Pine Barrens
Different suites of meteorological and biophysical factors characterize spring vs. summer in the Pine Barrens of New Jersey, leading to contrasting fire behaviors. This system has sandy, well-drained soils and nutrient-poor litter that is resistant to decay, resulting in the rapid accumulation of fine fuel. We are using a combination of meteorological and eddy covariance measurements along with estimates of forest biomass and forest floor mass to evaluate a hydrologic model for the Pine Barrens, focusing on the dynamic moisture content of fine and live fuels. We are also using a mesonet of fire weather stations to refine near-surface predictions of an atmospheric mesoscale model (MM5) for the Pine Barrens. In spring, passage of synoptic fronts leads to rapid increases in wind speed and low-level atmospheric turbulence, a rapid decrease in relative humidity, modification of the land/sea-breeze process, and high Haines Index values over the region. During this season, sparse canopies result in relatively high solar radiation flux at the forest floor, leading to large fluctuations in the moisture content of fine fuels. This dynamic behavior has been difficult to model within the National Fire Danger Rating System (NFDRS). Forest fires during the spring are typically fast moving but low intensity. In summer, the land/sea-breeze process dominates the lower atmosphere. High leaf area of deciduous understory shrubs results in a large amount of live fuel, and supports high rates of evapotranspiration. High LAI, rapidly fluctuating water contents of fuels, and short canopy stature can result in laddering and severe crown fires. Our research will ultimately lead to a more responsive fuel model for the Northeastern Coastal Plain.