Showing papers in "Atmospheric Environment in 1998"

TL;DR: This paper presents a general introduction and discussion of recent applications of the multilayer perceptron, one type of artificial neural network, in the atmospheric sciences.

TL;DR: In this paper, a broad overview and synthesis of current knowledge and understanding pertaining to all major aspects of mercury in the atmosphere is presented, including physical, chemical, and toxicological properties of this element.

TL;DR: In this article, the authors summarized the current knowledge on the calculation and application of trajectories and their different techniques that can be used to compute trajectories, and their error sources are described.

TL;DR: In this paper, a comprehensive validation of FLEXPART, a recently developed Lagrangian particle dispersion model based on meteorological data from the European Centre for Medium-Range Weather Forecasts, is described.

TL;DR: The Modal Aerosol Dynamics model for Europe (MADE) as discussed by the authors was developed as an extension to mesoscale chemistry transport models to allow a more detailed treatment of aerosol effects in these models.

TL;DR: In this paper, the authors reviewed and re-analyzed the historical data and some modeling results for D for H 2 O, CO 2, CH 4, CO, O 3, SO 2, NH 3, N 2 O, NO, and NO 2 in air, N 2 and O 2.

TL;DR: In this paper, an improvement upon the Lettau relationship is derived starting from fundamental principles, based on certain assumptions about the velocity profile, and the improved model includes the obstacle drag coefficient explicitly, and accounts for the peak in the z 0 versus area density curve.

TL;DR: In this paper, the atmospheric degradation of 120 organic compounds and the associated regional scale ozone and PAN formation under conditions appropriate to the polluted boundary layer over northwest Europe were analyzed. And the robustness of these POCP values to changes in the NOx emission densities across Europe is tested and the values are compared with previous studies.

TL;DR: In this paper, Nitrous oxide emissions were measured from several grassland and arable soils in the field, and from two of these soils and a forest soil transferred in large monoliths to a greenhouse.

TL;DR: In this article, traffic related air pollution was measured indoors and outdoors in six city districts near motorways in the West of the Netherlands, and the gradients for NO2 and black smoke were curvilinear and more evident in periods that the city districts had been downwind from the motorway for at least 33% of the time.

TL;DR: In this article, a Teflon-based dynamic chamber was used to measure soil mercury flux, and it was found that background soil accounts for the gross emission of ∼ 109 g yr −1 of Hg° to the atmosphere, with approximately two-thirds of this total from sunlightexposed soil and the remainder from forest and other shaded-soil ecosystems.

TL;DR: In this paper, an intensive field measurement campaign has been achieved during the summer of 1995 using high-time resolution techniques (10 min) at two sites (land and water) in southern Quebec (Canada).

TL;DR: In this paper, the authors reviewed the current understanding of chemical and dynamical processes in the upper troposphere and lower stratosphere, and assessed how these processes could be perturbed as a result of current and future aircraft emissions.

TL;DR: In this article, the authors measured the deposition of polycyclic aromatic hydrocarbons, hexachlorobenzene and polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans to a coniferous and a deciduous forest canopy.

TL;DR: In this paper, the authors present information to support programs that mitigate urban heat islands with solar-reflective surfaces: estimates of the achievable increase in albedo for a variety of surfaces, issues related to the selection of materials and costs and benefits of using them.

TL;DR: In this paper, the authors measured ammonium, nitrate, and dissolved organic nitrogen in 60 precipitation events collected from May, 1993 to December 1994 at a site near the Chesapeake Bay, an estuary currently experiencing eutrophication.

TL;DR: In this article, a tower-based micrometeorological gradient method for measuring gas-phase Hg fluxes over soils and vegetation was developed, showing that Hg° exchange over these surfaces is bidirectional, but is primarily characterized by emissions from plants and soil.

TL;DR: In this paper, process-based ecosystem models were used to estimate global CH4 emissions from natural wetlands and rice paddies, and the sensitivity of the models to simple climate change scenarios were tested.

TL;DR: In this paper, the HONO formation rate on stratospheric aerosol by the parallel reaction of NO 2 with sulphuric acid ( c H 2 SO 4 >60 wt%) was investigated.

TL;DR: The monoterpene, isoprene, and light hydrocarbon emission rates of tea-leafed willow ( Salix phylicifolia), aspen ( Populus tremula ), and silver birch ( Betula pendula ) were measured using a dynamic flow-through technique as discussed by the authors.

TL;DR: In this article, the emissions of two volatile organic compounds (VOCs) of concern from five building products (BPs) were measured in the field and laboratory emission cell (FLEC) up to 250 d.

TL;DR: In this article, static chamber measurements of CH4 flux were made from a range of micro-environments in an area of blanket bog in Northern Scotland, and investigations into the response of net CH4 emission rates to temperature and water table were carried out under semi-natural conditions on 45 large peat monoliths, maintained in open top chambers, over a three-year period.

TL;DR: In this article, the ozone-forming potential of biogenic hydrocarbon emissions from trees and shrubs was estimated using the California South Coast Air Basin (SoCAB) as a case study.

TL;DR: In this article, a preliminary Monte Carloun certainty analysis system has been developed and the methodology has been demonstrated using an application of the standard U.S. regulatory model, UAM-IV, to the 230-km by 290-km New York City domain for the 6-8 July 1988 ozone episode.

TL;DR: In this article, five years data on CO, NO, NO2, O3, smoke and SO2 concentrations recorded at one air-pollution monitoring station in the city of Athens were analyzed using principal component analysis(PCA).

TL;DR: The results of two years of monitoring and research on urban particulates with a focus on submicrometer particles, conducted as a part of an ongoing program on comprehensive characterization of fine airborne particulates and their effect on environmental and human exposures, are presented in this paper.

TL;DR: In this paper, two new resistance models are described to estimate a "canopy compensation point" (C d ) as the net potential for NH 3 emission from the canopy, which is based on the competition between deposition to leaf surfaces and bi-directional exchange with a stomatal compensation point for leaf tissues.

TL;DR: In this paper, the Lagrange duality relation is used to estimate the strength of the source using the influence function obtained as a solution of the adjoint equation, which is applicable for a large class of toxic materials either for the verification of the existing emission inventories or, as a sole method, for assessing the source term.

TL;DR: In this paper, a method for the analysis of carboxylic acids in aerosols was developed, based on the collection of particles on Teflon filters (2.5 cm diameter with a 0.4μm pore size), extraction with dichloromethane, and derivatization with BF3-methanol followed by analysis of the formed methylesters by large volume injection GC/MS.

TL;DR: In this paper, a simplified method for calculating advection of mixing ratios in a mass conservative and monotonic manner is presented, which employs a special treatment near local maxima and minima to preserve extremes very well.