16 research outputs found
La llicenciatura en FĂsica: Perfil de la professiĂł. Estudi dâinserciĂł professional
Les oportunitats professionals dels llicenciats i llicenciades en FĂsica han evolucionat
molt en el passat immediat, i tambĂ© sâha ampliat els tipus de sectors
laborals que enrolen fĂsics. Fa just trenta anys, la major part dels titulats era
absorbida pel sector de lâensenyament secundari i superior. Una minoria aconseguia
fer carrera de recerca, principalment en centres acadĂšmics. En lâactualitat
el panorama ha canviat força ja que, com revelen algunes enquestes a graduats
recents de mitjan els anys noranta, la sortida professional de lâensenyament
només representava un 50 % del total
Climatology of ozone âminiâholeâ events and their influence on UV solar radiation in Barcelona (Spain)
Cloud cover analysis associated to cut-off low-pressure systems over Europe using Meteosat Imagery
© Springer-Verlag 2006. This work was supported by the Spanish Ministry of Science and Technology (MCYT), under grant REN2002-04558-C04-04.This paper reports a cloud cover analysis of cut-off low pressure systems (COL) using a pattern recognition method applied to IR and VIS bispectral histograms. 35 COL occurrences were studied over five years (1994-1998). Five cloud types were identified in COLs, of which high clouds (HCC) and deep convective clouds (DCC) were found to be the most relevant to characterize COL systems, though not the most numerous. Cloud cover in a COL is highly dependent on its stage of development, but a higher percentage of cloud cover is always present in the frontal zone, attributable due to higher amounts of high and deep convective clouds. These general characteristics are most marked during the first stage (when the amplitude of the geopotencial wave increases) and second stage (characterized by the development of a cold upper level low), closed cyclonic circulation minimizing differences between rearward and frontal zones during the third stage. The probability of heavy rains during this stage decreases considerably. The centres of mass of high and deep convective clouds move towards the COL-axis centre during COL evolution.Spanish Ministry of Science and Technology (MCYT)Depto. de FĂsica de la Tierra y AstrofĂsicaFac. de Ciencias FĂsicasTRUEpu
Quality control process of the daily rainfall series available in Catalonia from 1855 to the present
The quality control of weather data is a necessity and a responsibility of meteorological services that store, distribute, and use these data. In the present work, a newly designed quality control procedure for daily rainfall data is presented after it has been adjusted and tested with more than 10^7 data from 1726 daily rainfall measurement sites in Catalonia. It is applicable to data from different origins (e.g., automatic weather stations or manual historical measurements). The procedure is focused on relative comparison of daily data with reference stations that are automatically selected after an initial estimation of their quality and a proximity study regarding location and correlation. The presented procedure has been verified taking advantage of an available network in the study area that has been routinely quality controlled by technicians of the Meteorological Service of Catalonia. The newly designed quality control procedure for daily precipitation yields good results, especially for extreme values: type I error under 10% is found for values up to 150 mm (error decreasing for lower values) and type II error is under 16% when reported values are twice a measure of 50 mm or more (error decreasing for more extreme values). After the application of the quality control procedure, a selection of series with the minimum desired quality is achieved.Peer Reviewe
La llicenciatura en FĂsica: Perfil de la professiĂł. Estudi dâinserciĂł professional
Les oportunitats professionals dels llicenciats i llicenciades en FĂsica han evolucionat
molt en el passat immediat, i tambĂ© sâha ampliat els tipus de sectors
laborals que enrolen fĂsics. Fa just trenta anys, la major part dels titulats era
absorbida pel sector de lâensenyament secundari i superior. Una minoria aconseguia
fer carrera de recerca, principalment en centres acadĂšmics. En lâactualitat
el panorama ha canviat força ja que, com revelen algunes enquestes a graduats
recents de mitjan els anys noranta, la sortida professional de lâensenyament
només representava un 50 % del total
Analysis of the precipitation and cloudiness associated with COLs occurrence in the Iberian Peninsula
The Iberian Peninsula is one of the regions in the world with higher occurrence of cut-off low systems (COL). The aim of this paper is to analyse the weather events (rainfall and cloudiness layer) associated to COLs in the Iberian Peninsula with tools not previously used: (a) the use of the new multidecadal COLs database developed by Nieto et al (2005) that permit us to study a 41 years period (1958-1998), (b) the checking of the expected weather events (rainfall and cloudiness layer) associated with COLs in a conceptual model (Winkler et al, 2005) and (c) the extensive use of radiosoundings to analyse convective instability in areas inside and close to the COL. Two points of view are used to make the analysis: (1) a source oriented method, when a particular COL is followed and its associated precipitation and cloudiness is analysed over four quadrants in which Iberia was divided and (2) a receptor oriented method, when the precipitation associated to COLs is analysed in given areas, defined by patterns of precipitation. Results reveal that the precipitation and cloudiness patterns associated to COLs in the conceptual model reproduce quite well the main characteristics found over the Iberian Peninsula. The generalized idea that most of the COLs produce intense convective rainfall is show to be misleading. Convective phenomena are important usually when the centre of the COL is located on the Mediterranean region. Most of the rainfall associated with COLs comes from the baroclinic shield; specially in cases located over the west half of the Iberian Peninsula. It is shown that nearly 30% of COLs do not induce any rainfall; most of them located in the southern half of the Peninsula, and mainly during autumn. Only 30% of COLs produce generalized rainfall over the whole analysed territory, being most of them (about 90%) located over the western half of the Iberian Peninsula
Cloud cover analysis associated to cut-off low-pressure systems over Europe using Meteosat Imagery
This paper reports a cloud cover analysis of cut-off low pressure systems (COL) using a pattern recognition method applied to IR and VIS bispectral histograms. 35 COL occurrences were studied over five years (1994-1998). Five cloud types were identified in COLs, of which high clouds (HCC) and deep convective clouds (DCC) were found to be the most relevant to characterize COL systems, though not the most numerous. Cloud cover in a COL is highly dependent on its stage of development, but a higher percentage of cloud cover is always present in the frontal zone, attributable due to higher amounts of high and deep convective clouds. These general characteristics are most marked during the first stage (when the amplitude of the geopotencial wave increases) and second stage (characterized by the development of a cold upper level low), closed cyclonic circulation minimizing differences between rearward and frontal zones during the third stage. The probability of heavy rains during this stage decreases considerably. The centres of mass of high and deep convective clouds move towards the COL-axis centre during COL evolution