A coupled atmospheric/wildfire behavior model is described that utilizes physics-based process models to represent wildfire behavior. Five simulations are presented, four of which highly idealized situations meant illustrate some the dependencies on environmental conditions. The fifth simulation consists a fire burning in complex terrain with non-homogeneous vegetation and realistic meteorological simulated develops out coupling set very processes not from prescribed rules based empirical...

A large number of hydrocarbons, halocarbons, and organic nitrates were quantified in whole air samples acquired for the NASA-sponsored GTE missions PEM-Tropics B. The collected electro-polished stainless steel canisters from two aircraft while flying over Pacific Basin. Two nominally identical multicolumn multidetector gas chromatographic analytical systems employed. Whole also used as working calibrated standards specifically this purpose. This paper describes procedure employed during...

In this text we describe an initial attempt to incorporate discrete porous element fuel beds into the coupled atmosphere–wildfire behavior model HIGRAD/FIRETEC. First develop conceptual models for use in translating measured tree data (in case a ponderosa pine forest) elements. Then collected at experimental sites near Flagstaff, Arizona are used create discontinuous canopy representation Four simulations presented with different and understory configurations as described text. The results...

Ten simulations were performed with the HIGRAD/FIRETEC wildfire behaviour model in order to explore its utility studying inhomogeneous topography. The goal of these is potential extent coupling between fire, atmosphere, and ten described this paper include five different topographies, each run two ambient wind speeds 6 12 m s–1. topologies explored are: an idealised hill (which serves as base centerline for other topographies), variations lateral gradients downwind from ignition line (one...

The atmospheric residence time for methyl bromide (CH3Br) has been estimated as 0.8 +/- 0.1 years from its empirical spatial variability relative to C2H6, C2Cl4, CHCl3, and CH3Cl. This evaluation of the time, based on Junge's 1963 general proposal, provides an estimate CH3Br that is independent source sink estimates. Methyl combined natural anthropogenic sources furnishes about half bromine enters stratosphere, where it plays important role in ozone destruction. consistent with 0.7-year...

Nonmethane hydrocarbons (NMHCs) and selected halocarbons were measured in whole air samples collected over the remote Pacific Ocean during NASA's Global Tropospheric Experiment (GTE) Exploratory Mission‐Tropics B (PEM‐Tropics B) March early April 1999. The large‐scale spatial distributions of NMHCs C 2 Cl 4 reveal a much more pronounced north‐south interhemispheric gradient, with higher concentrations north lower levels south, than for late August to October 1996 PEM‐Tropics A experiment....

Multi-instrument studies have recently shed new light on the morphology of sporadic E, especially intense E. Here we present simultaneous observations dense E ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:msub><mml:mrow><mml:mtext>E</mml:mtext></mml:mrow><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math> ) structures using Long Wavelength Array (LWA) radio telescopes and a Digisonde Portable Sounder 4D (DPS4D). Our coordinated show...

Abstract A climatology of VLF (very low frequency) wave intensity from lightning in the plasmasphere is constructed. Starting Optical Transient Detector/Lightning Imaging Sensor (OTD/LIS) data representing 1995–2005, a strikes assembled with 1° × latitude‐longitude spatial resolution, averaged into 2 h bins for each month year. Assuming linear relationship between optical flash rate and power flux, that amplitude drops off as one over distance, proxy developed. typical spectrum applied...

Irradiation of gaseous carbon disulfide [CS2(g)] at 313 nanometers produces a dark brown aerosol (CS2)x. Its thermal decomposition products include disulfur (S2), monosulfide (CS), and (CS)x. The photopolymerization process is accompanied by large mass-independent isotopic fractionation sulfur (a 5 to 10 per mil sulfur-33 excess 61 84 sulfur-36 deficit). Excess has been observed in several classes meteorites. Photochemical production (CS2)x may be important the origin evolution cosmochemical...

Detailed Boltzmann kinetic calculations of the electron distribution functions resulting from thermal runaway in a constant electric field are presented. Thermal is considered to occur when an initially accelerated above 150 eV peak dynamical friction force air and becomes electron. We investigate role breakdown situations where runaway, as well conventional breakdown, occurring. The strengths studied span range threshold for (∼0.3 MV/m at sea level) through (2.4–3.2 exceeding Dreicer (25...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotopolymerization of Carbon Disulfide Yields the High-Pressure-Phase (CS2)xJonah J. Colman and William C. TroglerCite this: Am. Chem. Soc. 1995, 117, 45, 11270–11277Publication Date (Print):November 1, 1995Publication History Published online1 May 2002Published inissue 1 November 1995https://pubs.acs.org/doi/10.1021/ja00150a026https://doi.org/10.1021/ja00150a026research-articleACS PublicationsRequest reuse permissionsArticle...

HIGRAD/FIRETEC is a coupled atmosphere/wildfire behavior model based on conservation of mass, momentum, species, and energy. It combines three-dimensional transport that uses compressible-gas fluid dynamics formulation with physics-based wildfire model, to represent the local atmosphere wildfire. In its current formulation, combustion pyrolysis are treated as single process, which depends densities wood oxygen, levels turbulent mixing, probability distribution function (PDF) for temperature...

Hydrocarbon and halocarbon measurements collected during the second airborne Biomass Burning Lightning Experiment (BIBLE‐B) were subjected to a principal component analysis (PCA), test capability for identifying intercorrelated compounds within large whole air data set. The BIBLE expeditions have sought quantify understand products of burning, electrical discharge, general atmospheric chemical processes flights arrayed along western edge Pacific. Principal was found offer compact method...

Abstract The geolocation of an uncooperative HF emitter is based on observations the azimuth and elevation (angle arrival; AoA) its signals as they arrive at a surveillance site, along with model propagation medium. simplest that provides estimate location use horizontal mirror placed appropriate altitude. If there are large‐scale ionospheric gradients or traveling disturbances present, tilts derived from suitable ionosonde AoA convenient known emitters (check targets) may be applied to...

Abstract Horizontal phase speeds for a medium‐scale traveling ionospheric disturbance (TID) are calculated from three different atmospheric gravity wave (AGW) dispersion relations using vertical derived ionograms measured by single ionosonde. Observed heights network of four ionosondes in southern New Mexico provide the velocities. compared to TID as function altitude and show general agreement. However, linear relationship between horizontal AGW this frequency wavenumber range predicts...

Abstract We constructed a program, we call “Iriatten,” to calculate using parameters from the International Reference Ionosphere, attenuation of Very Low Frequency (VLF) radiation transiting ionosphere. The calculations are performed as function latitude, longitude, year, month, day, and hour based upon quasi‐longitudinal approximation put forth by Helliwell, where wave vector k , is in direction propagation, follows Earth's magnetic field lines. best values various taken literature....

Abstract The ionosphere contains many small‐scale electron density variations that are under represented in smooth physics‐based or climatological models. This can negatively impact the results of Observation System Simulation Experiments, which use a truth model to simulate data. paper addresses this problem by using ionosonde data study ionospheric variability and build new with empirically driven variations. studied for their amplitude, horizontal vertical size, temporal extent. Results...

The photochemistry of carbon disulfide was examined over a concentration range that pertains to tropospheric conditions. At low mixing ratios (67.79, 282.4, and 485.4 parts per billion by volume (ppbv)) in air, photochemical oxidation is very slow carbonyl sulfide (OCS) product not observed. Upper limits were established for the quantum yield based on practical OCS quantification limit 10 ppbv (ΦOCS&lt;0.0022, 0.00079, 0.00045, respectively). Solar photolysis at ratio 282.4 gave...

The relationship between the variability (relative standard deviation, σ) in mixing ratio of a gas and its global mean lifetime (τ) has been used to estimate τ atmospheric gases. This can prove quite useful if it is unique relationship. Here three‐dimensional chemical transport model investigate variability‐lifetime tropospheric gases with two types sources three losses. effects sampling time location are also explored. best described form σ = ατ −β , where α β variable depending on sources,...