1,720,988 research outputs found
Analysis of pyrheliometric measurements at Modena (Italy) from 1990 to 1991
No full textDuring the last few years continuous measurements of direct solar irradiance have been taken in Modena (37 m. a.s.l.) using pyrheliometers with three filters (quartz filters, OG51, RG61). The apparent atmospheric transmission calculated using the so-called rationing technique can be utilised as a useful parameter to monitor the atmosphere. Preliminary results suggest that the atmospheric transmission seems be able to highlight meteorological events such as the transport of dust
Influence of the Mediterranean Sea over intense precipitation events
No full textThe Mediterranean basin and, in particular the Alpine region, was affected by some intense precipitation events during recent years. The complex orography surrounding the region and the presence of a relatively warm sea like the Mediterranean make this region very difficult to study from the point of view of the features of the atmospheric flow. Some of these events were selected inside an International Project called MAP (Mesoscale Alpine Program) and are object of intensive study in order to go into the knowledge of aspects which are not fully understood or not adequately represented in the atmospheric models. A series of simulations of one of these events events was analyzed in order to point out the main forcing which played an important role in the spatial and temporal determination of the episode and in the intensity of precipitation
Numerical Mesoscale Analysis of selected MAP intense precipitation episodes
No full textIn the framework of the International MAP Project, several intense precipitation events were selected and are currently object of intensive study in the pre-campaign phase of the project, in order to verify the capability of the atmospheric numerical models to reproduce the pattern of precipitation field and the main features of the atmospheric flow and to analyze in details the meteorological situations leading to such events. In this respect, two of the selected MAP episodes were simulated using a mesoscale version of the Eta Model which is run operationally in various national and regional Meteorological Services
Impact of modified resolutions on the numerical simulations of Vaison-La-Romaine flash-flood
No full textThe Vaison-la-Romaine flash-flood occurred on September 22nd 1992 is an example of intense precipitation events characterising the fall season in the Mediterranean area. Numerical simulations of the Vaison-la-Romaine case have been carried out using the 1993 version of the Eta Model, which is a grid point model, based on the primitive equations in hydrostatic approximation. The series of numerical simulations was done combining different horizontal (40 and 20 km) and vertical (16 and 38 levels) resolutions, in order to point out their impact on the representation of precipitation field in respect to the observations available from MAP Data Center
Effect of the elimination of the sea surface fluxes on Piedmont flood
No full textIn the framework of the Internationa MAP Project, a series of simulations using the Eta Model relative to the intense precipitation event was performed in order to point out the influence of the sea on this episode. On the whole, the results suggest that the sea surface fluxes affect the convective precipitation on the local scale, while the large scale component of the precipitation is almost unaffected
PIXE APPLICATION IN THE STUDY OF POLLUTANT ENRICHMENT IN MARINE AEROSOLS
No full textPOLLUTANT ENRICHMENT IN MARINE AEROSOLS IS STUDIED BY MEANS OF PIXE MEASUREMENTS OF AEROSOL SAMPLES FROM SEA WATE
DISINFECTION PROCESS IMPACT ON WATER QUALITY IN AN AQUEDUCT DISTRIBUTION NET
No full textA NEW PROCEDURE IS PRESENTED TO EVALUATE THE DISINFECTION PROCESS IMPACT ON WATER QUALITY IN AN AQUEDUCT DISTRIBUTION NE
Numerical mesoscale simulations of the atmospheric flow over Antarctica
No full textThe atmospheric circulation over Antarctica during January 1994 is simulated using a limited area model, Eta model (version 1993, 55km horizontal resolution, 17 levels). The simulations are performed with initialized analyses from European Centre for Medium Range Weather Forecasts (ECMWF) as initial and boundary conditions. The results are in good agreement with the analyses even if the mesoscale features on the high Plateau are poorly represented. The model deficiency over the Plateau is emphasised in the medium-range simulation. Additional comparisons of model results and AWS observations will be presented
Modelling study of Mesoscale Cyclogenesis over Ross Sea,Antarctica,on February 18,1988
Full text linkThis paper examines the development of a summer event of mesoscale cyclogenesis off the coast of Victoria Land in the presence of katabatic winds, by means of numerical simulations. These refer to the period from 00 UTC 17 February to 00 UTC 19 February 1988 and were performed using the hydrostatic ETA (1993 version) limited area model with resolution 55 km x 55 km x 17 levels. The ETA model reproduces katabatic winds from Terra Nova Bay and a trough on the southwestern Ross Sea. A cyclonic vortex is simulated in the trough, even though it is weaker than the one present in the analyses initialized by the European Center for Medium Range Weather Forecast (Reading, UK). Idealized simulations with varied surface conditions were also performed. In particular, an ice-covered ocean acts to weaken the atmospheric phenomena, while a no-mountain simulation emphasizes the influence of the orography and the cold winds from the coast of Victoria Land on the mesocyclonic activity
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