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The Global Fire Assimilation System (GFAS) assimilates Fire Radiative Power (FRP) observations from satellite-based sensors to produce daily estimates of biomass burning emissions. It has been extended to include information about injection heights provided by two distinct algorithms, which also use meteorological information from the operational weather forecasts of ECMWF. Injection heights are provided by the semi-empirical IS4FIRES parameterization and an analytical one-dimension Plume Rise Model (PRM). The two algorithms provide estimates for injection heights for each satellite pixel. Similarly to how FRP observations are processed in GFAS, these estimates are then gridded, averaged and assimilated, using a simple observation operator, so as to fill the observational gaps. A global database of daily biomass burning emissions and injection heights at 0.1° resolution has been produced for 2003-2015. The database is being extended in near-real-time with the operational GFAS service of the Copernicus Atmospheric Monitoring Service (CAMS). The two injection height datasets were compared against a new dataset of satellite-based plume height observations. The IS4FIRES parameterization showed a better overall agreement against observations, while the PRM was better at capturing the variability of injection heights and at estimating the injection heights of large fires. The results from both also show a differentiation depending on the type of vegetation. A positive trend with time in median injection heights from the PRM was noted, less marked from the IS4FIRES parameterization. This is provoked by a negative trend in number of small fires, especially in regions such as South America. The use of biomass burning emission heights from GFAS in atmospheric composition forecasts was assessed in two case studies: the South AMerican Biomass Burning Analysis (SAMBBA) campaign which took place in September 2012 in Brazil, and a series of large fire events in the Western U.S. in August 2013. For these case studies, forecasts of biomass burning aerosol species by the Composition-Integrated Forecasting System (C-IFS) of CAMS were found to better reproduce the observed vertical distribution when using PRM injection heights from GFAS. [ABSTRACT FROM AUTHOR]

Landscape fires produce smoke containing a very wide variety of chemical species, both gases and aerosols. For larger, more intense fires that produce the greatest amounts of emissions per unit time, the smoke tends initially to be transported vertically or semi-vertically close by the source region, driven by the intense heat and convective energy released by the burning vegetation. The column of hot smoke rapidly entrains cooler ambient air, forming a rising plume within which the fire emissions are transported. This characteristics of this plume, and in particular the height to which it rises before releasing the majority of the smoke burden into the wider atmosphere, are important in terms of how the fire emissions are ultimately transported, since for example winds at different altitudes maybe quite different. This difference in atmospheric transport then may also affect the longevity, chemical conversion and fate of the plumes chemical consituents, with for example very high plume injection heights being associated with extreme long-range atmospheric transport. Here we review how such landscape-scale fire smoke plume injection heights are represented in larger scale atmospheric transport models aiming to represent the impacts of wildfire emissions on component of the Earth system. The use of satellite Earth observation (EO) data is commonly used for this, and detail the EO datasets capable of being used to remotely assess wildfire plume height distributions and the driving characteristics of the causal fires. We also discus both the physical mechanisms and dynamics taking place in fire plumes, and investigate the efficiency and limitations of currently available injection height parameterizations. Finally, we conclude by suggestion some future parameterization developments and ideas on EO data selection that maybe relevant to the instigation of enhanced methodologies aimed at injection height representation. [ABSTRACT FROM AUTHOR]

We use observations of fire size 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 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 size observations as input to the plume rise model. We find that convective heat fluxes and actual fire sizes 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 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 actual fire size 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-+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 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 distributing gases and particles in the atmosphere using global MOPITT CO observations (or any current space-borne 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. [ABSTRACT FROM AUTHOR]

Wild-fires release huge amounts of aerosol and hazardous trace gases in the atmosphere. The residence time and the dispersion of fire pollutants in the atmosphere can range from hours to days and from local to continental scales. These various scenarios highly depend on the injection height of smoke plumes. The altitude at which fire products are injected in the atmosphere is controlled by fire characteristics and meteorological conditions. Injection height however is still poorly accounted in chemistry transport models for which fires are sub-grid scale processes which need to be parametrised. Only recently, physically-based approaches for estimating the fire injection heights have been developed which consider both the convective updrafts induced by the release of fire sensible heat and the impact of background meteorological environment on the fire convection dynamics. In this work, two different models are used to simulate fire injection heights in contrasted meteorological scenarios: a Mediterranean arson fire and two Amazonian deforestation fires. A Eddy-Diffusivity/Mass-Flux approach, for merly developed to reproduce convective boundary layer in the non-hydrostatic meteorological model Meso-NH, is compared to the 1-D Plume Rise Model. For both models, radiosonde data and re-analyses from the European Center for Medium-Range Weather Forecasts (ECMWF) have been used as initial conditions to explore the sensitivity of the models responses to different meteorological forcings. The two models predict injection heights for the Mediterranean fire between 1.7 and 3.3 km with the Meso-NH/EDMF model systematically higher than the 1-D PRM model. Both models show a limited sensitivity to the meteorological forcings with a 20-30% difference in the injection height between radiosondes and ECMWF data for this case. Injection heights calculated for the two Amazonian fires ranges from 5 to 6.5km for the 1-D PRM model and from 2 to 4 km for the Meso-NH/EDMF model. The difference of smoke plume heights between the two models can reach 3-4 km. A large difference is obtained for the windy-wet Amazonian fire by the 1-D PRM model with a injection height 1.5km higher when ECMWF re-analyses are used compared to the run with the radiosonde forcing. For the Mediterranean case, both models forecast a plume injection height above the boundary layer, although there are evidences that this particular fire propagated near the surface, highlighting the current limitations of the two approaches. [ABSTRACT FROM AUTHOR]

This study describes high-resolution numerical simulations of the evolution of an aircraft contrail and its transition into a contrail-cirrus. The contrail is modeled as a vortex pair descending in a stratified atmosphere where turbulent fluctuations are sustained in the late regime of diffusion. The focus of this study is laid on the three-dimensional vortex dynamics - including vortex instability and turbulence - and on the interaction between dynamics and microphysics and its role in determining the growth and the distribution of ice crystals. The results show the feasibility of three-dimensional simulations of the entire lifetime of a contrail until its transformation into a contrail-cirrus in supersaturated conditions. In particular, it is shown that the contrail-cirrus optical depth is maintained as the cloud expands, in agreement with available observations. [ABSTRACT FROM AUTHOR]

There is an urgent need for next-generation smoke research and forecasting (SRF) systems to meet the challenges of the growing air quality, health, and safety concerns associated with wildland fire emissions. This review paper presents simulations and experiments of hypothetical prescribed burns with a suite of selected fire behavior and smoke models and identifies major issues for model improvement and the most critical observational needs. The results are used to understand the new and improved capability required for the next-generation SRF systems and to support the design of the Fire and Smoke Model Evaluation Experiment (FASMEE) and other field campaigns. The next-generation SRF systems should have more coupling of fire, smoke, and atmospheric processes to better simulate and forecast vertical smoke distributions and multiple sub-plumes, dynamical and high-resolution fire processes, and local and regional smoke chemistry during day and night. The development of the coupling capability requires comprehensive and spatially and temporally integrated measurements across the various disciplines to characterize flame and energy structure (e.g., individual cells, vertical heat profile and the height of well mixing flaming gases), smoke structure (vertical distributions and multiple sub-plumes), ambient air processes (smoke eddy, entrainment and radiative effects of smoke aerosols), fire emissions (for different fuel types and combustion conditions from flaming to residual smoldering), as well as night-time processes (smoke drainage and super-fog formation).

The reaction of 2-(omega-alkenyl)benzoic acids with bis(collidine)iodine and bis(collidine)bromine hexafluorophosphate was examined. Except with 2-but-3-enylbenzoic acid, for which only the exo lactone was obtained, for the other acids a mixture of exo-endo lactones was always obtained. The proportion of endo lactone was important for the acid chain length of 11 carbons (formation of a 12-membered ring endo lactone) and for the acid chain lengths higher than 14 carbons. The formation of the endo lactones was explained, on the base of molecular calculations, by competition between electronic and steric effects. These latter were developed by transannular interactions (for the acid chain lengths 8-11) and/or the conformations adopted by the chains (for the acid chain lengths > or = 14,) which disfavored the formation of the exo lactones. The larger proportion of endo lactones observed with the bromo reagent compared to the iodo reagent seemed due to electronic factors.

One-pot palladium(0)-catalyzed alkylation and S(N)(') cyclization of 1,4-dichlorobut-2-ene 1 by the anion of alpha-substituted carbonitriles 2a-d can provide highly functionalized cyclopropanes (E)-4a-d, diastereoselectivity, (de 88-100%). Several attempts to achieve the asymmetric synthesis of the 1-amino-2-ethenylcyclopropanecarbonitrile (E)-9, by means of this new procedure, i.e., using chiral palladium ligands, chiral aminoacetonitriles (-)- and (+)-12 (from 1-hydroxypinanone) or chiral allyl chlorides (4S)-20b-d and (4R)-20e (from (2S) ethyl lactate) have pointed up the reversibility of the palladium-catalyzed cyclization step, responsible for the low enantioselectivity observed (ee 88%) and provided the enantiomerically enriched 1-amino-2-propenylcyclopropanecarbonitrile (E)-22 (ee > 83%) suitable precursor of (1S,2S)-2,3-methanoamino acids.