Title: Toward Developing a Climatology of Fire Emissions in Central Asia,
Fire emissions are a significant mechanism in the carbon cycling from the Earth’s surface to the atmosphere, and fire behavior is considerably interacted with weather and climate. However, due to interannual variation of the emissions and nonlinear smoke plume dynamics, understanding the interactions between fire behavior and the atmosphere is challenging. This study aims to establish a climatology of the fire emission in Central Asia and has estimated a feedback of fire emissions to meteorological variables on a seasonal basis using the Weather Research and Forecasting model coupled with Chemistry. The months of April, May, and September have a relatively large number of pixels, where the plume height is located within the boundary layer, and the domain during these months tends to have unstable conditions at the strongest smoke, showing a lower percentage of stable conditions. From the seasonal analysis, the high fire intensity occurs in the summer as smoke travels above the boundary layer, changing temperature profile and increasing the water vapor mixing ratio. more »« less
Mallia, Derek V.; Kochanski, Adam K.; Urbanski, Shawn P.; Mandel, Jan; Farguell, Angel; Krueger, Steven K.
(, Atmosphere)
null
(Ed.)
Forecasting fire growth, plume rise and smoke impacts on air quality remains a challenging task. Wildland fires dynamically interact with the atmosphere, which can impact fire behavior, plume rises, and smoke dispersion. For understory fires, the fire propagation is driven by winds attenuated by the forest canopy. However, most numerical weather prediction models providing meteorological forcing for fire models are unable to resolve canopy winds. In this study, an improved canopy model parameterization was implemented within a coupled fire-atmosphere model (WRF-SFIRE) to simulate a prescribed burn within a forested plot. Simulations with and without a canopy wind model were generated to determine the sensitivity of fire growth, plume rise, and smoke dispersion to canopy effects on near-surface wind flow. Results presented here found strong linkages between the simulated fire rate of spread, heat release and smoke plume evolution. The standard WRF-SFIRE configuration, which uses a logarithmic interpolation to estimate sub-canopy winds, overestimated wind speeds (by a factor 2), fire growth rates and plume rise heights. WRF-SFIRE simulations that implemented a canopy model based on a non-dimensional wind profile, saw significant improvements in sub-canopy winds, fire growth rates and smoke dispersion when evaluated with observations.
Ye, Xinxin; Arab, Pargoal; Ahmadov, Ravan; James, Eric; Grell, Georg A.; Pierce, Bradley; Kumar, Aditya; Makar, Paul; Chen, Jack; Davignon, Didier; et al
(, Atmospheric Chemistry and Physics)
Abstract. Wildfire smoke is one of the most significant concerns ofhuman and environmental health, associated with its substantial impacts onair quality, weather, and climate. However, biomass burning emissions andsmoke remain among the largest sources of uncertainties in air qualityforecasts. In this study, we evaluate the smoke emissions and plumeforecasts from 12 state-of-the-art air quality forecasting systemsduring the Williams Flats fire in Washington State, US, August 2019, whichwas intensively observed during the Fire Influence on Regional to GlobalEnvironments and Air Quality (FIREX-AQ) field campaign. Model forecasts withlead times within 1 d are intercompared under the same framework basedon observations from multiple platforms to reveal their performanceregarding fire emissions, aerosol optical depth (AOD), surface PM2.5,plume injection, and surface PM2.5 to AOD ratio. The comparison ofsmoke organic carbon (OC) emissions suggests a large range of daily totalsamong the models, with a factor of 20 to 50. Limited representations of thediurnal patterns and day-to-day variations of emissions highlight the needto incorporate new methodologies to predict the temporal evolution andreduce uncertainty of smoke emission estimates. The evaluation of smoke AOD(sAOD) forecasts suggests overall underpredictions in both the magnitude andsmoke plume area for nearly all models, although the high-resolution modelshave a better representation of the fine-scale structures of smoke plumes.The models driven by fire radiativepower (FRP)-based fire emissions or assimilating satellite AODdata generally outperform the others. Additionally, limitations of thepersistence assumption used when predicting smoke emissions are revealed bysubstantial underpredictions of sAOD on 8 August 2019, mainly over thetransported smoke plumes, owing to the underestimated emissions on7 August. In contrast, the surface smoke PM2.5 (sPM2.5) forecastsshow both positive and negative overall biases for these models, with mostmembers presenting more considerable diurnal variations of sPM2.5.Overpredictions of sPM2.5 are found for the models driven by FRP-basedemissions during nighttime, suggesting the necessity to improve verticalemission allocation within and above the planetary boundary layer (PBL).Smoke injection heights are further evaluated using the NASA LangleyResearch Center's Differential Absorption High Spectral Resolution Lidar(DIAL-HSRL) data collected during the flight observations. As the firebecame stronger over 3–8 August, the plume height became deeper, with aday-to-day range of about 2–9 km a.g.l. However, narrower ranges arefound for all models, with a tendency of overpredicting the plume heights forthe shallower injection transects and underpredicting for the days showingdeeper injections. The misrepresented plume injection heights lead toinaccurate vertical plume allocations along the transects corresponding totransported smoke that is 1 d old. Discrepancies in model performance forsurface PM2.5 and AOD are further suggested by the evaluation of theirratio, which cannot be compensated for by solely adjusting the smoke emissionsbut are more attributable to model representations of plume injections,besides other possible factors including the evolution of PBL depths andaerosol optical property assumptions. By consolidating multiple forecastsystems, these results provide strategic insight on pathways to improvesmoke forecasts.
Ye, Xinxin; Saide, Pablo E.; Hair, Johnathan; Fenn, Marta; Shingler, Taylor; Soja, Amber; Gargulinski, Emily; Wiggins, Elizabeth
(, Journal of Geophysical Research: Atmospheres)
Abstract Wildfire emissions are a key contributor of carbonaceous aerosols and trace gases to the atmosphere. Induced by buoyant lifting, smoke plumes can be injected into the free troposphere and lower stratosphere, which by consequence significantly affects the magnitude and distance of their influences on air quality and radiation budget. However, the vertical allocation of emissions when smoke escapes the planetary boundary layer (PBL) and the mechanism modulating it remain unclear. We present an inverse modeling framework to estimate the wildfire emissions, with their temporal and vertical evolution being constrained by assimilating aerosol extinction profiles observed from the airborne Differential Absorption Lidar‐High Spectral Resolution Lidar during the Fire Influence on Regional to Global Environments and Air Quality field campaign. Three fire events in the western U.S., which exhibit free‐tropospheric injections are examined. The constrained smoke emissions indicate considerably larger fractions of smoke injected above the PBL (f>PBL, 80%–94%) versus the column total, compared to those estimated by the WRF‐Chem model using the default plume rise option (12%–52%). The updated emission profiles yield improvements for the simulated vertical structures of the downwind transported smoke, but limited refinement of regional smoke aerosol optical depth distributions due to the spatiotemporal coverage of flight observations. These results highlight the significance of improving vertical allocation of fire emissions on advancing the modeling and forecasting of the environmental impacts of smoke.
Deng, Min; Volkamer, Rainer M.; Wang, Zhien; Snider, Jefferson R.; Kille, Natalie; Romero-Alvarez, Leidy J.
(, Journal of Atmospheric and Oceanic Technology)
Abstract The western U.S. wildfire smoke plumes observed by the upward-pointing Wyoming Cloud Lidar (WCL) during the Biomass Burning Fluxes of Trace Gases and Aerosols (BB-FLUX) project are investigated in a two-part paper. Part II here presents the reconstructed vertical structures of seven plumes from airborne WCL measurements. The vertical structures evident in the fire plume cross sections, supported by in situ measurements, showed that the fire plumes had distinct macrophysical and microphysical properties, which are closely related to the plume transport, fire emission intensity, and thermodynamic structure in the boundary layer. All plumes had an injection layer between 2.8 and 4.0 km above mean sea level, which is generally below the identified boundary layer top height. Plumes that transported upward out of the boundary layer, such as the Rabbit Foot and Pole Creek fires, formed a higher plume at around 5.5 km. The largest and highest Pole Creek fire plume was transported farthest and was sampled by University of Wyoming King Air aircraft at 170 km, or 2.3 h, downwind. It was associated with the warmest, driest, deepest boundary layer and the highest wind speed and turbulence. The Watson Creek fire plume intensified in the afternoon with stronger CO emission and larger smoke plume height than in the morning, indicating a fire diurnal cycle, but some fire plumes did not intensify in the afternoon. There were pockets of relatively large irregular aerosol particles at the tops of plumes from active fires. In less-active fire plumes, the WCL depolarization ratio and passive cavity aerosol spectrometer probe mass mean diameter maximized at a height that was low in the plume.
Mallia, Derek V.; Kochanski, Adam K.; Kelly, Kerry E.; Whitaker, Ross; Xing, Wei; Mitchell, Logan E.; Jacques, Alex; Farguell, Angel; Mandel, Jan; Gaillardon, Pierre‐Emmanuel; et al
(, Journal of Geophysical Research: Atmospheres)
Abstract One of the primary challenges associated with evaluating smoke models is the availability of observations. The limited density of traditional air quality monitoring networks makes evaluating wildfire smoke transport challenging, particularly over regions where smoke plumes exhibit significant spatiotemporal variability. In this study, we analyzed smoke dispersion for the 2018 Pole Creek and Bald Mountain Fires, which were located in central Utah. Smoke simulations were generated using a coupled fire‐atmosphere model, which simultaneously renders fire growth, fire emissions, plume rise, smoke dispersion, and fire‐atmosphere interactions. Smoke simulations were evaluated using PM2.5observations from publicly accessible fixed sites and a semicontinuously running mobile platform. Calibrated measurements of PM2.5made by low‐cost sensors from the Air Quality and yoU (AQ&U) network were within 10% of values reported at nearby air quality sites that used Federal Equivalent Methods. Furthermore, results from this study show that low‐cost sensor networks and mobile measurements are useful for characterizing smoke plumes while also serving as an invaluable data set for evaluating smoke transport models. Finally, coupled fire‐atmosphere model simulations were able to capture the spatiotemporal variability of wildfire smoke in complex terrain for an isolated smoke event caused by local fires. Results here suggest that resolving local drainage flow could be critical for simulating smoke transport in regions of significant topographic relief.
Park, Y. H., and Sokolik, Irina N. Toward Developing a Climatology of Fire Emissions in Central Asia,. Retrieved from https://par.nsf.gov/biblio/10026391. Air, soil and water research 9.
Park, Y. H., & Sokolik, Irina N. Toward Developing a Climatology of Fire Emissions in Central Asia,. Air, soil and water research, 9 (). Retrieved from https://par.nsf.gov/biblio/10026391.
Park, Y. H., and Sokolik, Irina N.
"Toward Developing a Climatology of Fire Emissions in Central Asia,". Air, soil and water research 9 (). Country unknown/Code not available. https://par.nsf.gov/biblio/10026391.
@article{osti_10026391,
place = {Country unknown/Code not available},
title = {Toward Developing a Climatology of Fire Emissions in Central Asia,},
url = {https://par.nsf.gov/biblio/10026391},
abstractNote = {Fire emissions are a significant mechanism in the carbon cycling from the Earth’s surface to the atmosphere, and fire behavior is considerably interacted with weather and climate. However, due to interannual variation of the emissions and nonlinear smoke plume dynamics, understanding the interactions between fire behavior and the atmosphere is challenging. This study aims to establish a climatology of the fire emission in Central Asia and has estimated a feedback of fire emissions to meteorological variables on a seasonal basis using the Weather Research and Forecasting model coupled with Chemistry. The months of April, May, and September have a relatively large number of pixels, where the plume height is located within the boundary layer, and the domain during these months tends to have unstable conditions at the strongest smoke, showing a lower percentage of stable conditions. From the seasonal analysis, the high fire intensity occurs in the summer as smoke travels above the boundary layer, changing temperature profile and increasing the water vapor mixing ratio.},
journal = {Air, soil and water research},
volume = {9},
author = {Park, Y. H. and Sokolik, Irina N.},
}
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