Optimizing Smoke and Plume Rise Modeling Approaches at Local Scales

Heating from wildfires adds buoyancy to the overlying air, often producing plumes that vertically distribute fire emissions throughout the atmospheric column over the fire. The height of the rising wildfire plume is a complex function of the size of the wildfire, fire heat flux, plume geometry, and atmospheric conditions, which can make simulating plume rises difficult with coarser-scale atmospheric models. To determine the altitude of fire emission injection, several plume rise parameterizations have been developed in an effort estimate the height of the wildfire plume rise. Previous work has indicated the performance of these plume rise parameterizations has generally been mixed when validated against satellite observations. However, it is often difficult to evaluate the performance of plume rise parameterizations due to the significant uncertainties associated with fire input parameters such as fire heat fluxes and area. In order to reduce the uncertainties of fire input parameters, we applied an atmospheric modeling framework with different plume rise parameterizations to a well constrained prescribed burn, as part of the RxCADRE field experiment. Initial results found that the model was unable to reasonably replicate downwind smoke for cases when fire emissions were emitted at the surface and released at the top of the plume. However, when fire emissions were distributed below the plume top following a Gaussian distribution, model results were significantly improved.

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Capturing Plume Rise and Dispersion with a Coupled Large-Eddy Simulation: Case Study of a Prescribed Burn

Atmosphere ◽

10.3390/atmos10100579 ◽

2019 ◽

Vol 10 (10) ◽

pp. 579

Author(s):

Nadya Moisseeva ◽

Roland Stull

Keyword(s):

Large Eddy Simulation ◽

Numerical Models ◽

Real Life ◽

Plume Rise ◽

Atmospheric Conditions ◽

Prescribed Burn ◽

Smoke Plume ◽

Fire Emissions ◽

Eddy Simulation ◽

Large Eddy

Current understanding of the buoyant rise and subsequent dispersion of smoke due to wildfires has been limited by the complexity of interactions between fire behavior and atmospheric conditions, as well as the uncertainty in model evaluation data. To assess the feasibility of using numerical models to address this knowledge gap, we designed a large-eddy simulation of a real-life prescribed burn using a coupled semi-emperical fire–atmosphere model. We used observational data to evaluate the simulated smoke plume, as well as to identify sources of model biases. The results suggest that the rise and dispersion of fire emissions are reasonably captured by the model, subject to accurate surface thermal forcing and relatively steady atmospheric conditions. Overall, encouraging model performance and the high level of detail offered by simulated data may help inform future smoke plume modeling work, plume-rise parameterizations and field experiment designs.

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Combining fire radiative power observations with the fire weather index improves the estimation of fire emissions

10.5194/acp-2017-790 ◽

2017 ◽

Cited By ~ 1

Author(s):

Francesca Di Giuseppe ◽

Samuel Rémy ◽

Florian Pappenberger ◽

Fredrik Wetterhall

Keyword(s):

Biomass Burning ◽

Atmospheric Composition ◽

Composition Analysis ◽

Fire Weather ◽

Atmospheric Conditions ◽

Weather Index ◽

Fire Weather Index ◽

Fire Emissions ◽

Radiative Power ◽

Fire Radiative Power

Abstract. The atmospheric composition analysis and forecast for the European Copernicus Atmosphere Monitoring Services (CAMS) relies on biomass burning fire emission estimates from the Global Fire Assimilation System (GFAS). GFAS converts fire radiative power (FRP) observations from MODIS satellites into smoke constituents. Missing observations are filled in using persistence where observed FRP from the previous day are progressed in time until a new observation is recorded. One of the consequences of this assumption is an overestimation of fire duration, which in turn translates into an overestimation of emissions from fires. In this study persistence is replaced by modelled predictions using the Canadian Fire Weather Index (FWI), which describes how atmospheric conditions affect the vegetation moisture content and ultimately fire duration. The skill in predicting emissions from biomass burning is improved with the new technique, which indicates that using an FWI-based model to infer emissions from FRP is better than persistence when observations are not available.

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Factors controlling variability in the oxidative capacity of the troposphere since the Last Glacial Maximum

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-24517-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 24517-24603 ◽

Cited By ~ 2

Author(s):

L. T. Murray ◽

L. J. Mickley ◽

J. O. Kaplan ◽

E. D. Sofen ◽

M. Pfeiffer ◽

...

Keyword(s):

Water Vapor ◽

Last Glacial Maximum ◽

Oxidative Capacity ◽

Glacial Maximum ◽

Modeling Framework ◽

Fire Emissions ◽

Last Glacial ◽

The Last Glacial Maximum ◽

Global Mean ◽

The Last Glacial

Abstract. The oxidative capacity of past atmospheres is highly uncertain. We present here a new climate-biosphere-chemistry modeling framework to determine oxidant levels in the present and past troposphere. We use the GEOS-Chem chemical transport model driven by meteorological fields from the NASA Goddard Institute of Space Studies (GISS) ModelE, with land cover and fire emissions from dynamic global vegetation models. We present time-slice simulations for the present day, late preindustrial (AD 1770), and the Last Glacial Maximum (LGM; 19–23 ka), and we test the sensitivity of model results to uncertainty in lightning and fire emissions. We find that most preindustrial and paleo climate simulations yield reduced oxidant levels relative to the present day. Contrary to prior studies, tropospheric mean OH in our ensemble shows little change at the LGM relative to the preindustrial (0.5 ± 12%), despite large reductions in methane concentrations. We find a simple linear relationship between tropospheric mean ozone photolysis rates, water vapor, and total emissions of NOx and reactive carbon that explains 72% of the variability in global mean OH in 11 different simulations across the last glacial-interglacial time interval and the Industrial Era. Key parameters controlling the tropospheric oxidative capacity over glacial-interglacial periods include overhead stratospheric ozone, tropospheric water vapor, and lightning NOx emissions. Variability in global mean OH since the LGM is insensitive to fire emissions. Our simulations are broadly consistent with ice-core records of Δ17O in sulfate and nitrate at the LGM, and CO, HCHO, and H2O2 in the preindustrial. Our results imply that the glacial-interglacial changes in atmospheric methane observed in ice cores are predominantly driven by changes in its sources as opposed to its sink with OH.

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Soil Moisture-Boundary Layer Feedbacks on the Loess Plateau in China Using Radiosonde Data with 1-D Atmospheric Boundary Layer Model

Atmosphere ◽

10.3390/atmos12121619 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1619

Author(s):

Yingsai Ma ◽

Xianhong Meng ◽

Yinhuan Ao ◽

Ye Yu ◽

Guangwei Li ◽

...

Keyword(s):

Boundary Layer ◽

Soil Moisture ◽

Atmospheric Boundary Layer ◽

Loess Plateau ◽

Atmospheric Stability ◽

Heat Fluxes ◽

Radiosonde Data ◽

Atmospheric Conditions ◽

The Loess Plateau ◽

The Impact

The Loess Plateau is one land-atmosphere coupling hotspot. Soil moisture has an influence on atmospheric boundary layer development under specific early-morning atmospheric thermodynamic structures. This paper investigates the sensitivity of atmospheric convection to soil moisture conditions over the Loess Plateau in China by using the convective triggering potential (CTP)—humidity index (HIlow) framework. The CTP indicates atmospheric stability and the HIlow indicates atmospheric humidity in the low-level atmosphere. By comparing the model outcomes with the observations, the one-dimensional model achieves realistic daily behavior of the radiation and surface heat fluxes and the mixed layer properties with appropriate modifications. New CTP-HIlow thresholds for soil moisture-atmosphere feedbacks are found in the Loess Plateau area. By applying the new thresholds with long-time scales sounding data, we conclude that negative feedback is dominant in the north and west portion of the Loess Plateau; positive feedback is predominant in the south and east portion. In general, this framework has predictive significance for the impact of soil moisture on precipitation. By using this new CTP-HIlow framework, we can determine under what atmospheric conditions soil moisture can affect the triggering of precipitation and under what atmospheric conditions soil moisture has no influence on the triggering of precipitation.

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Snow-ice growth: a fresh-water flux inhibiting deep convection in the Weddell Sea, Antarctica

Annals of Glaciology ◽

10.3189/172756401781818752 ◽

2001 ◽

Vol 33 ◽

pp. 45-50 ◽

Cited By ~ 14

Author(s):

V.I. Lytle ◽

S.F. Ackley

Keyword(s):

Sea Ice ◽

Thermohaline Circulation ◽

Deep Convection ◽

Ice Cover ◽

Snow Accumulation ◽

Heat Fluxes ◽

Weddell Sea ◽

Salt Flux ◽

Ice Formation ◽

Atmospheric Conditions

AbstractDuring a field experiment in July 1994, while the R.V. Nathaniel B. Palmer was moored to a drifting ice floe in the Weddell Sea, Antarctica, data were collected on sea-ice and snow characteristics. We report on the evolution of ice which grew in a newly opened lead. As expected with cold atmospheric conditions, congelation ice initially formed in the lead. Subsequent snow accumulation and large ocean heat fluxes resulted in melt at the base of the ice, and enhanced flooding of the snow on the ice surface. This flooded snow subsequently froze, and, 5 days after the lead opened, all the congelation ice had melted and 26 cm of snow ice had formed. We use measured sea-ice and snow salinities, thickness and oxygen isotope values of the newly formed lead ice to calculate the salt flux to the ocean. Although there was a salt flux to the ocean as the ice initially grew, we calculate a small net fresh-wlter input to the upper ocean by the end of the 5 day period. Similar processes of basal melt and surface snow-ice formation also occurred on the surrounding, thicker sea ice. Oceanographic studies in this region of the Weddell Sea have shown that salt rejection by sea-ice formation may enhance the ocean vertical thermohaline circulation and release heat from the deeper ocean to melt the ice cover. This type of deep convection is thought to initiate the Weddell polynya, which was observed only during the 1970s. Our results, which show that an ice cover can form with no salt input to the ocean, provide a mechanism which may help explain the more recent absence of the Weddell polynya.

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Validation and Parametric Investigations of an Internal Permanent Magnet Motor Using a Lumped Parameter Thermal Model

Journal of Electronic Packaging ◽

10.1115/1.4053121 ◽

2021 ◽

Author(s):

Sebastien Sequeira ◽

Kevin Bennion ◽

J. Emily Cousineau ◽

Sreekant Narumanchi ◽

Gilberto Moreno ◽

...

Keyword(s):

Experimental Data ◽

Sensitivity Analysis ◽

Permanent Magnet ◽

Power Density ◽

Heat Removal ◽

Maximum Difference ◽

Modeling Framework ◽

Element Analysis ◽

Lumped Parameter ◽

Input Parameters

Abstract One of the key challenges for the electric vehicle industry is to develop high-power-density electric motors. Achieving higher power density requires efficient heat removal from inside the motor. In order to improve thermal management, a multi-physics modeling framework that is able to accurately predict the behavior of the motor, while being computationally efficient, is essential. This paper first presents a detailed validation of a Lumped Parameter Thermal Network (LPTN) model of an Internal Permanent Magnet synchronous motor within the commercially available Motor-CAD® modeling environment. The validation is based on temperature comparison with experimental data and with more detailed Finite Element Analysis (FEA). All critical input parameters of the LPTN are considered in detail for each layer of the stator, especially the contact resistances between the impregnation, liner, laminations and housing. Finally, a sensitivity analysis for each of the critical input parameters is provided. A maximum difference of 4% - for the highest temperature in the slot-winding and the end-winding - was found between the LPTN and the experimental data. Comparing the results from the LPTN and the FEA model, the maximum difference was 2% for the highest temperature in the slot-winding and end-winding. As for the LTPN sensitivity analysis, the thermal parameter with the highest sensitivity was found to be the liner-to-lamination contact resistance.

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Regional oceanic and biogeochemical modeling strategy :forced or coupled model ?

10.5194/egusphere-egu21-9240 ◽

2021 ◽

Author(s):

Véra Oerder ◽

Pierre-Amaël Auger ◽

Joaquim Bento ◽

Samuel Hormazabal

Keyword(s):

High Resolution ◽

Wind Stress ◽

Coupled Model ◽

Heat Fluxes ◽

Atmospheric Conditions ◽

Coupled Simulation ◽

Biogeochemical Modeling ◽

Ocean Atmosphere ◽

The Impact ◽

Oceanic Model

Regional high resolution biogeochemical modeling studies generaly use an oceanic model forced by prescribed atmospheric conditions. The computational cost of such approach is far lower than using an high resolution ocean-atmosphere coupled model. However, forced oceanic models cannot represent adequately the atmospheric reponse to the oceanic mesoscale (~10-100km) structures and the impact on the oceanic dynamics.To assess the bias introduce by the use of a forced model, we compare here a regional high resolution (1/12&#186;) ocean-atmosphere coupled model with oceanic simulations forced by the outputs of the coupled simulation. Several classical forcing strategies are compared : bulk formulae, prescribed stress, prescribed heat fluxes with or without Sea Surface Temperature (SST) restoring term, .... We study the Chile Eastern Boundary Upwelling System, and the oceanic model includes a biogeochemical component,The coupled model oceanic mesoscale impacts the atmosphere through surface current and SST anomalies. Surface currents mainly affect the wind stress while SST impacts both the wind stress and the heat fluxes. In the forced simulations, mesoscale structures generated by the model internal variability does not correspond to those of the coupled simulation. According to the forcing strategy, the atmospheric conditions are not modified by the forced model mesoscale, or the modifications are not realistic. The regional dynamics (coastal upwelling, mesoscale activity, &#8230;) is affected, with impact on the biogeochemical activity.&#160;&#160;This work was supported by the FONDECYT project 3180472 (Chile), with computational support of the NLHPC from the Universidad de Chile, the HPC from the Pontificia Universidad Catolica de Valparaiso and the Irene HPC from the GENCI at the CEA (France).

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Smoke incursions into urban areas: simulation of a Georgia prescribed burn

International Journal of Wildland Fire ◽

10.1071/wf08082 ◽

2009 ◽

Vol 18 (3) ◽

pp. 336 ◽

Cited By ~ 31

Author(s):

Yongqiang Liu ◽

Scott Goodrick ◽

Gary Achtemeier ◽

William A. Jackson ◽

John J. Qu ◽

...

Keyword(s):

Air Quality ◽

Urban Areas ◽

Ambient Air ◽

Quality Standard ◽

Prescribed Burn ◽

Modeling Framework ◽

North West ◽

Transport Direction ◽

Smoke Plumes ◽

Ambient Air Quality Standard

This study investigates smoke incursion into urban areas by examining a prescribed burn in central Georgia, USA, on 28 February 2007. Simulations were conducted with a regional modeling framework to understand transport, dispersion, and structure of smoke plumes, the air quality effects, sensitivity to emissions, and the roles of burn management strategy in mitigating the effects. The results indicate that smoke plumes first went west, but turned north-west at noon owing to a shift in wind direction. The smoke then invaded metropolitan Atlanta during the evening rush hour. The plumes caused severe air quality problems in Atlanta. Some hourly ground PM2.5 (particulate matter not greater than 2.5 μm in diameter) concentrations at three metropolitan Atlanta locations were three to four times as high as the daily (24-h) US National Ambient Air Quality Standard. The simulated shift in the smoke transport direction and the resultant effects on air quality are supported by the satellite and ambient air measurements. Two sensitivity simulations indicate a nearly linear relation between the emission intensities and PM2.5 concentrations. Two other simulations indicate that the impacts on air quality for the residents of Atlanta during the evening commute could have been reduced if the starting time of the burn had been altered.

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Implied Ocean Heat Transports in the Standard and Superparameterized Community Atmospheric Models

Journal of Climate ◽

10.1175/2009jcli2987.1 ◽

2010 ◽

Vol 23 (7) ◽

pp. 1908-1928 ◽

Cited By ~ 10

Author(s):

Charlotte A. DeMott ◽

David A. Randall ◽

Marat Khairoutdinov

Keyword(s):

Surface Energy ◽

Latent Heat ◽

Cloud Microphysics ◽

Heat Fluxes ◽

Shortwave Radiation ◽

Trade Wind ◽

Modeling Framework ◽

Marine Stratocumulus ◽

Stratocumulus Clouds ◽

Ice Water

Abstract Implied ocean heat transport (To) based on net surface energy budgets is computed for two versions of the Community Atmospheric Model (CAM, version 3.0) general circulation model (GCM). The first version is the standard CAM with parameterized convection. The second is the multiscale modeling framework (MMF), in which parameterized convection is replaced with a two-dimensional cloud-resolving model in each GCM grid column. Although global-mean net surface energy totals are similar for both models, differences in the geographic distributions of the component errors lead to distinctly different To for each model, with CAM’s To generally agreeing with observationally based To estimates, and the MMF’s To producing northward transport at all latitudes north of ∼50°S. Analysis of component error sources in the To calculation identifies needed improvements in the MMF. Net surface shortwave radiation and latent heat fluxes over the oceans are the primary causes of To errors in the MMF. Surface shortwave radiation biases in the MMF are associated with liquid and/or ice water content biases in tropical and extratropical convection and a deficit of marine stratocumulus clouds. It is expected that tropical ice water contents in the MMF can be made more realistic via improvements to the cloud microphysics parameterization. MMF marine stratocumulus clouds are overly sensitive to low-level relative humidity and form only with nearly saturated conditions and a shallow boundary layer. Latent heat flux errors in the MMF are amplifications of those found in the CAM and are concentrated in the trade wind regime and the Asian monsoon region and the adjacent western Pacific Ocean. Potential improvements to To are estimated by replacing either simulated net surface shortwave or latent heat fluxes with those from observations and recomputing To. When observed shortwave fluxes are used, both CAM and MMF produce greatly improved To curves for both hemispheres. When To is computed using observed latent heat fluxes, CAM To degrades slightly and MMF To improves, especially in the sign of Southern Hemisphere transport.

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Quantifying pyroconvective injection heights using observations of fire energy: sensitivity of spaceborne observations of carbon monoxide

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-4339-2015 ◽

2015 ◽

Vol 15 (8) ◽

pp. 4339-4355 ◽

Cited By ~ 11

Author(s):

S. Gonzi ◽

P. I. Palmer ◽

R. Paugam ◽

M. Wooster ◽

M. N. Deeter

Keyword(s):

Heat Flux ◽

Carbon Monoxide ◽

Convective Heat ◽

Biomass Burning ◽

Environmental Conditions ◽

Heat Fluxes ◽

Plume Rise ◽

Convective Heat Flux ◽

Active Fire ◽

Fire Area

Abstract. We use observations of active fire area and fire radiative power (FRP) from the NASA Moderate Resolution Imaging Spectroradiometers (MODIS), together with a parameterized plume rise model, to estimate biomass burning injection heights during 2006. We use these injection heights in the GEOS-Chem (Goddard Earth Observing System Chemistry) atmospheric chemistry transport model to vertically distribute biomass burning emissions of carbon monoxide (CO) and to study the resulting atmospheric distribution. For 2006, we use over half a million FRP and fire area observations as input to the plume rise model. We find that convective heat fluxes and active fire area typically lie in the range of 1–100 kW m−2 and 0.001–100 ha, respectively, although in rare circumstances the convective heat flux can exceed 500 kW m−2. The resulting injection heights have a skewed probability distribution with approximately 80% of the injections remaining within the local boundary layer (BL), with occasional injection height exceeding 8 km. We do not find a strong correlation between the FRP-inferred surface convective heat flux and the resulting injection height, with environmental conditions often acting as a barrier to rapid vertical mixing even where the convective heat flux and active fire area are large. We also do not find a robust relationship between the underlying burnt vegetation type and the injection height. We find that CO columns calculated using the MODIS-inferred injection height (MODIS-INJ) are typically −9 to +6% different to the control calculation in which emissions are emitted into the BL, with differences typically largest over the point of emission. After applying MOPITT (Measurement of Pollution in the Troposphere) v5 scene-dependent averaging kernels we find that we are much less sensitive to our choice of injection height profile. The differences between the MOPITT and the model CO columns (max bias ~ 50%), due largely to uncertainties in emission inventories, are much larger than those introduced by the injection heights. We show that including a realistic diurnal variation in FRP (peaking in the afternoon) or accounting for subgrid-scale emission errors does not alter our main conclusions. Finally, we use a Bayesian maximum a posteriori approach constrained by MOPITT CO profiles to estimate the CO emissions but because of the inherent bias between model and MOPITT we find little impact on the resulting emission estimates. Studying the role of pyroconvection in the distribution of gases and particles in the atmosphere using global MOPITT CO observations (or any current spaceborne measurement of the atmosphere) is still associated with large errors, with the exception of a small subset of large fires and favourable environmental conditions, which will consequently lead to a bias in any analysis on a global scale.

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