Search results for "oceanic"
showing 10 items of 642 documents
A Theoretical Study of the Wet Removal of Atmospheric Pollutants. Part II: The Uptake and Redistribution Of (NH4)2SO4Particles and SO2Gas Simultaneou…
1987
Abstract A theoretical model has been formulated which allows the processes which control the wet deposition of atmospheric aerosol particles and pollutant gases to be included in cloud dynamic models. The cloud considered in the model was allowed to grow by condensation and collision–coalescence, to remove aerosol particles by nucleation and impaction scavenging, and to remove pollutant gases by convective diffusion. The model was tested by using a simple air-parcel model as the dynamic framework. In this form the model was used to determine the fate of ammonium sulfate [(NH4)2SO4] particles and sulfur dioxide (SO2) gas as they became scavenged by cloud and precipitation drops. Special emp…
Numerical simulations of air pollutant dispersion in a stratified planetary boundary layer
1978
Abstract A numerical model is described for computing pollutant concentration distributions downwind from a source. It is based on the three-dimensional dispersion equation governing the time-dependent advective and diffusive transport of air pollutants and is solved numerically by a mixed Lagrangian-Eulerian finite-difference scheme. The model includes the vertical wind shear, the turning of the actual wind, and vertical variations of the vertical eddy diffusivity. In this paper the model is used to simulate the pollutant dispersion process in a stratified planetary boundary layer. The vertical profiles of horizontal mean wind and vertical eddy diffusivities are calculated numerically from…
Laboratory Studies of Scattering Properties of Polluted Cloud Droplets: Implications for FSSP Measurements
2008
Abstract Laboratory experiments were conducted in the Mainz vertical wind tunnel to study the effects of pollutants dissolved or suspended in cloud droplets on the droplet size measurements of a Forward Scattering Spectrometer Probe (FSSP). The FSSP is a widely used instrument to derive microphysical properties of atmospheric clouds. Individual droplets of different well-defined sizes were freely falling at their terminal velocities in the wind tunnel while the intensity of radiation emitted by the He–Ne laser of the FSSP and scattered by the droplets was measured. For this purpose, the FSSP was adapted and mounted to the wind tunnel. The intensity of radiation scattered by the droplets in …
Sensitivity of low-level clouds and precipitation to anthropogenic aerosol emission in southern West Africa: a DACCIWA case study
2021
Abstract. During the West African summer monsoon, pollutants emitted in urbanized coastal areas modify cloud cover and precipitation patterns. The Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa (DACCIWA) field campaign provided numerous aircraft-based and ground-based observations, which are used here to evaluate two experiments made with the coupled WRF-CHIMERE model, integrating both the direct and indirect aerosol effect on meteorology. During one well-documented week (1–7 July 2016), the impacts of anthropogenic aerosols on the diurnal cycle of low-level clouds and precipitation are analyzed in detail using high and moderate intensity of anthropogenic emissions in the expe…
On Inverse Distance Weighting in Pollution Models
2011
When evaluating the impact of pollution, measurements from remote stations are often weighted by the inverse of distance raised to some nonnegative power (IDW). This is derived from Shepard's method of spatial interpolation (1968). The paper discusses the arbitrary character of the exponent of distance and the problem of monitoring stations that are close to the reference point. From elementary laws of physics, it is determined which exponent of distance should be chosen (or its upper bound) depending on the form of pollution encountered, such as radiant pollution (including radioactivity and sound), air pollution (plumes, puffs, and motionless clouds by using the classical Gaussian model),…
Pollution models and inverse distance weighting: some critical remarks
2013
International audience; When evaluating the impact of pollution, measurements from remote stations are often weighted by the inverse of distance raised to some nonnegative power (IDW). This is derived from Shepard's method of spatial interpolation (1968). The paper discusses the arbitrary character of the exponent of distance and the problem of monitoring stations that are close to the reference point. From elementary laws of physics, it is determined which exponent of distance should be chosen (or its upper bound) depending on the form of pollution encountered, such as radiant pollution (including radioactivity and sound), air pollution (plumes, puffs, and motionless clouds by using the cl…
Szukając wolności: Sprawa kapitana m/s "Batory" Jana Ćwiklińskiego
2014
After WWII the Polish ocean liner “Batory” operated on the route Gdynia–New York, and from 1951 to India. The captain of the ship was Jan Ćwikliński. The Ministry for Public Security accused him of having a hostile attitude towards the People’s Republic of Poland and insisted on him being removed from his position as Batory captain. In the spring of 1953 the ship underwent a technical check-up at a shipyard in Great Britain. In the mean-time it was rumoured that the captain was to be arrested upon his return to Poland on suspicion of espionage. When the renovation works were about to be completed, Ćwikliński decided to escape and left his ship for good. The captain was given political asylu…
Effects of Moisture and Stresses on the Structure and Properties of Polyester Resin
2004
The results of a complex study of structural changes in a cured Norpol 440 polyester resin under the action of damp environment and mechanical loading are presented. A considerable effect of absorbed moisture on the structure and some characteristics of the material is revealed by using thermophysical methods and X-ray diffractometry. The joint effect of moisture and mechanical stress is estimated by investigating the creep in stationary and nonstationary moisture conditions. The anisotropy of the material structure formed during creep is evaluated from the results of dilatometric measurements. It is found that the degree of anisotropy of the material after creep accompanied by moisture sor…