Abstract A two-dimensional version of the Pennsylvania State University mesoscale model has been applied to Winter Monsoon Experiment data in order to simulate the diurnally occurring convection observed over the South China Sea. The domain includes a representation of part of Borneo as well as the sea so that the model can simulate the initiation of convection. Also included in the model are parameterizations of mesoscale ice phase and moisture processes and longwave and shortwave radiation with a diurnal cycle. This allows use of the model to test the relative importance of various heating mechanisms to the stratiform cloud deck, which typically occupies several hundred kilometers of the domain. Frank and Cohen's cumulus parameterization scheme is employed to represent vital unresolved vertical transports in the convective area. The major conclusions are: Ice phase processes are important in determining the level of maximum large-scale heating and vertical motion because there is a strong anvil componen...

Numerical study of convection observed during the Winter Monsoon Experiment using a mesoscale two-dimensional model [presentation]

[i] An inventory of air pollutant emissions in Asia in the year 2000 is developed to support atmospheric modeling and analysis of observations taken during the TRACE-P experiment funded by the National Aeronautics and Space Administration (NASA) and the ACE-Asia experiment funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA). Emissions are estimated for all major anthropogenic sources, including biomass burning, in 64 regions of Asia. We estimate total Asian emissions as follows: 34.3 Tg SO 2 , 26.8 Tg NO x , 9870 Tg CO 2 , 279 Tg CO, 107 Tg CH 4 , 52.2 Tg NMVOC, 2.54 Tg black carbon (BC), 10.4 Tg organic carbon (OC), and 27.5 Tg NH 3 . In addition, NMVOC are speciated into 19 subcategories according to functional groups and reactivity. Thus we are able to identify the major source regions and types for many of the significant gaseous and particle emissions that influence pollutant concentrations in the vicinity of the TRACE-P and ACE-Asia field measurements. Emissions in China dominate the signature of pollutant concentrations in this region, so special emphasis has been placed on the development of emission estimates for China. China's emissions are determined to be as follows: 20.4 Tg SO 2 , 11.4 Tg NO x , 3820 Tg CO 2 , 116 Tg CO, 38.4 Tg CH 4 , 17.4 Tg NMVOC, 1.05 Tg BC, 3.4 Tg OC, and 13.6 Tg NH 3 . Emissions are gridded at a variety of spatial resolutions from 1° × 1° to 30 s x 30 s, using the exact locations of large point sources and surrogate GIS distributions of urban and rural population, road networks, landcover, ship lanes, etc. The gridded emission estimates have been used as inputs to atmospheric simulation models and have proven to be generally robust in comparison with field observations, though there is reason to think that emissions of CO and possibly BC may be underestimated. Monthly emission estimates for China are developed for each species to aid TRACE-P and ACE-Asia data interpretation. During the observation period of March/ April, emissions are roughly at their average values (one twelfth of annual). Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of ±16% for SO 2 to a high of ±450% for OC.

An inventory of gaseous and primary aerosol emissions in Asia in the year 2000 : NASA global tropospheric experiment transport and chemical evolution over the pacific (TRACE-P): Measurements and analysis (TRACEP1)

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Numerical Heat Transfer And Fluid Flow

https://hal-ineris.archives-ouvertes.fr/ineris-00961872/document

Modelling air quality in street canyons : a review

a time as one year after leaving the Rehabilitation Unit, and about one quarter were not in competitive jobs but were in sheltered employment. Only just over one quarter were still working in ordinary jobs. Their average wage was £8 I is. 6d. Furthermore if one compares the type of work these patients were able to perform there was a definite decline from their premorbid position. The social class grouping before and after rehabilitation was Class II, i-i, Class III, 9-3, Class IV, 4-6, and Class V, IO-I4. Indeed the authors report that 'even the least handicapped of these patients presented continuous problems . . .' and it is noted that such a programme requires special personnel and a great deal of work. Comparing these results with the extra cost in personnel, time, and effort (which could be directed elsewhere) a Doctor Beeching of the psychiatric services would probably scrap such a rehabilitation service before it even started. But is this the right way of looking at it? The authors point out that such a programme, if applied throughout the country, would affect about 6,ooo patients. If the failure rate were the same as in this experiment, about I,500 would be rescued from a disabled life in a mental hospital and once more returned to an at least partially useful and, one assumes, more satisfying life. Obviously more is involved here than mere economics. We were interested to read that as regards behaviour at the Rehabilitation Centre and during the follow-up year 'There were no outstanding differences' between the schizophrenic and the non-schizophrenic rehabilitees. It appears that the group of schizophrenics had difficulties in social adjustment which were even greater than those of work adjustment. '. . . the men concerned had greater difficulty in living outside hospital, than in working outside hospital. If, however, adequate arrangements are made to cater for these various needs, there seems to be every reason to expect that a small selected group of long stay schizophrenic patients can be successfully resettled in work.' The experiment and the report show the high standards we have come so confidently to expect from Dr. Wing and his colleagues, and the publication will be read with interest, not only by psychiatrists, but by all those concemed with rehabilitation problems of chronically disabled patients. J. HOENIG

https://oem.bmj.com/content/oemed/23/2/161.2.full.pdf

The Mechanics of Aerosols

A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k–ε turbulence model

A three-dimensional computational fluid dynamics model with the renormalization group k–e turbulence scheme is developed. The model developed is used to investigate the effects of ambient wind direction on flow and dispersion around a group of buildings. According to the ambient wind direction, three flow patterns are identified in a view of the characteristics of the mean flow circulation generated in street canyons. In the first flow pattern, a portal vortex generated behind the east wall of the upwind building is symmetric about the center of the street canyon. In the second flow pattern, a portal vortex is also generated behind the east wall of the upwind building, but its horizontal axis is not perpendicular to the ambient wind direction. In the third flow pattern, the footprints of a portal vortex are located behind both the east and north walls of the upwind building. When the incident wind angle is 45°, flow is diagonally symmetric behind the upwind building. As the incident wind angle increases, pollutant escape from the street canyons decreases. Except for the case where the ambient wind direction is perpendicular to the buildings, pollutants are trapped in the portal vortex, thus exhibiting high concentration there.

A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k-ε turbulence model

The flow and pollutant dispersion in urban street canyons are investigated using a two-dimensional numerical model with the k–e turbulent closure scheme. It is shown that the flow field is characterized mainly by the number and intensity of vortices produced in the street canyon. As the street aspect ratio (ratio of the building height to the width between buildings) increases, the number of vortices increases. In the upper-canyon region, the downward motion near the downwind building is stronger than the upward motion near the upwind building, and the turbulent kinetic energy (TKE) is higher near the downwind building than near the upwind building because of stronger wind shears near the downwind building. The TKE budget analysis shows that the shear production is high near the interface between the ambient flow and the street canyon flow and that the turbulent dissipation is also high where the shear production is high. The horizontal advection and diffusion are found to play a crucial role in ...

A Numerical Study of Flow and Pollutant Dispersion Characteristics in Urban Street Canyons

Urban street-canyon flows with bottom heating

This study investigates thermal effects on the flow and pollutant dispersion in urban street canyons. A two-dimensional numerical model with a k–ϵ turbulent closure scheme is developed, and the heat transfer between the air and the building wall or street-canyon bottom is effectively represented by a wall function. For each of seven cases with different aspect ratios (building height/width between buildings = 0.5, 1, 1.5, 2, 2.5, 3, and 3.5), four thermal situations (no heating, upwind building-wall heating, street-canyon bottom heating, and downwind building-wall heating) are considered. In the cases of upwind building-wall heating, one vortex appears regardless of aspect ratio. When the aspect ratio is greater than or equal to 1.5, the upward motion forced by upwind building-wall heating overcomes the downward motion that appears in the cases of no heating. In the cases of street-canyon bottom heating, when the aspect ratio is less than 3, flow patterns are similar to those in the cases of upwi...

Jae-Jin Kim

Papers

A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k–ε turbulence model

A numerical study of the effects of ambient wind direction on flow and dispersion in urban street canyons using the RNG k-ε turbulence model

A Numerical Study of Flow and Pollutant Dispersion Characteristics in Urban Street Canyons

Urban street-canyon flows with bottom heating

A Numerical Study of Thermal Effects on Flow and Pollutant Dispersion in Urban Street Canyons