AN APPLICATION OF CALPUFF DISPERSION MODEL TO A NON-STANDARD PROBLEM
Pulp and paper mill situated in the complex terrain of northern Slovakia, in the close vicinity of the city of Ružomberok, continuously releases to atmosphere 30 kg of water vapor per second. Impressive clouds above the industrial complex have given rise to concerns from the side of local citizens, suspecting the emissions to be responsible for the local increase in precipitation. Therefore, a complex study has been initiated, including model simulation of the dispersion of water vapor from the paper mill focused on the domain of 8 x 7 km in close vicinity of the paper mill. Phase conversions of water vapor in the atmosphere are a complex thermodynamic process involving many factors. However, we found out that for some practical applications a simplified approach is sufficient to assess the magnitude of the above mentioned effects. A combination of CALMET-CALPUFF models were applied to compute hourly concentrations of water vapor added to the atmosphere by emissions from the paper mill; these were compared to the hourly absolute humidity values as measured by the meteorological stations in the region, which are not supposed to be affected by the paper mill. The interest was focused on those hours in which the “background” absolute humidity was below saturation value, but additional vapor from the paper mill would bring the value to or above the saturation point. Winter periods of two years (2005, 2006) were modeled and analyzed, during which 66 hours occurred when the additional water from the paper mill caused the humidity to exceed the saturation point, compared to 478 hours with 100% background relative humidity, when the additional vapor from the mill could possibly strengthen the icing effect which would occur anyway. The study concludes that the contribution of the paper mill to total precipitation is negligible even in the close vicinity of the factory. However, in certain cases it can cause icings on a nearby E50 road communication; although these cases are not frequent, they can lead to fatal outcomes. The uncertainties associated with the study method are also discussed.
Cloud Condensation Nuclei from a Paper Mill. Part I: Measured Effects on Clouds
Abstract The effluents from a large Kraft-process paper mill were found to increase the concentration of large (0.2–2 μm diameter) and giant (>2 μm diameter) cloud condensation nuclei (CCN) above background concentrations; the concentrations of small (<0.2 μm diameter) CCN, however, were not increased significantly. Small, nonraining, warm cumulus clouds located in the plume of the paper mill were found to contain higher concentrations of droplets ≥30 μm diameter than similar clouds located outside of the plume; the clouds in both locations contained similar concentrations of droplets ≥5 μm diameter. Cloud droplet size distributions calculated using the CCN measurements are consistent with the measured droplet size distributions. It is concluded that the large and giant CCN from the paper mill increased the concentrations of droplets ≥30 μm diameter in clouds located in its plume. Furthermore, the clouds located in and out of the plume contained similar concentrations of droplets ≥5 μm diameter because th...
Detection of Urban-Induced Rainfall Anomalies in a Major Coastal City
There is increasing evidence that large coastal cities, like Houston, Texas, can influence weather through complex urban land use- weather-climate feedbacks. Recent work in the literature establishes the ex- istence of enhanced lightning activity over and downwind of Houston. Since lightning is a signature of convection in the atmosphere, it would seem rea- sonable that urbanized Houston would also impact the distribution of rainfall. This paper presents results using data from the world's first satellite-based precipitation radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) and ground-based rain gauges to quantify rainfall anomalies that we hypothesize to be linked to extensive urbanization in the Houston area. It is one of the first rigorous efforts to quantify an urban-induced rainfall anomaly near a major U.S. coastal city and one of the first applications of space-borne radar data to the problem. Quantitative results reveal the presence of annual and warm season rainfall anomalies over and downwind of Houston. Several hypotheses have surfaced to explain how the sea breeze, coastline curvature,