A Comparative Study between FLEXPART-WRF and HYSPLIT in an Operational Setting: Analysis of Fire Emissions across complex geography using WRF

Dispersion;FLEXPART-WRF;HYSPLIT

Pagano, Lara Elizabeth ; Ryan Boyles, Committee Chair,Sethu Raman, Committee Member,Hugh Devine, Committee Member,Helena Mitasova, Committee Member,Pagano, Lara Elizabeth ; Ryan Boyles ; Committee Chair ; Sethu Raman ; Committee Member ; Hugh Devine ; Committee Member ; Helena Mitasova ; Committee Member

University:North Carolina State University

关键词: Dispersion;    FLEXPART-WRF;    HYSPLIT;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/6293/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

Transport and dispersion models are frequently used by the meteorological community to understandand predict the trajectories of anthropogenic, natural and accidental chemical releases of hazardousmaterials. There are several reputable dispersion models that can handle a wide range of applicationsunder the direction of global, synoptic or mesoscale forecasts. One such application is the forecast ofsmoke emissions from wildfires which is important to operational air quality and meteorology communities.Fire emissions have direct impacts to property and respiratory health. Operational meteorologistsare responsible for providing meteorological support to emergency management agencies within theircounty warning area in the event of incidents involving harmful chemical releases, radiation and smokeemissions. A comparative study between two dispersion models during recent wildfire events acrosscomplex geography is presented to identify the sensitivities of each dispersion model and the operationalbenefits of utilizing each model for smoke emission forecasts.FLEXPART-WRF is a Lagrangian dispersion model that predicts the transport and dispersionof trace gases forward or backward from a point, line or area source. Similar to FLEXPART-WRF,the HYbrid Single Particle Integrated Trajectory (HYSPLIT) model simulates the dispersive nature ofthe environment. Model configuration differences include the prerequisite meteorological data, densitycorrection, dispersion algorithms and removal calculations.Mesoscale meteorological models are needed to provide the ambient environment as well as simulatethe small scale flux exchanges and boundary layer processes that can affect dispersion simulations ona local and regional scale. Therefore, both dispersion models are using meteorological input from theWRF ARW mesoscale atmospheric model using both a 12 km and 4 km grid-resolution domain.Two fire events, one along the coast of the Mid-Atlantic (Evans Road Case) and the other withinthe Appalachians (South Mountain Case), are investigated for this analysis. Simulations are analyzedto identify the relative performance of each dispersion model given identical meteorological input. Thedispersion models are evaluated for accurate dispersive simulations and also on their ability to supportoperational forecast needs. Satellite observations provided by the National Environmental Satellite,Data and Information Service along with other remote sensing tools are used for evaluation of dispersionmodel performance.The spatial analysis, based on both case studies and resolutions, indicates that HYSPLIT dispersesparticles 10-20 degrees to the right of FLEXPART-WRF for at least a portion of the simulations.FLEXPART-WRF better replicates the observed plume and also yields a higher air concentrationthroughout most of the simulations, especially downwind. These differences in plume compositionsand concentrations are likely linked to the differing diffusion equations. While the air concentrationdifferences are small compared to the amount being released, the spatial differences are statisticallysignificant. To account for the air concentration differences, dry deposition is analyzed. HYSPLITsporadically deposited significantly more mass to the ground compared to FLEXPART-WRF. Thesedeposition differences impact the diffusion process and account for only part of the concentrationvariations. This study suggests that FLEXPART-WRF performs better compared to HYSPLIT andmay serve as an improved operational tool.