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Based on the use of an objective classification method for the general atmospheric circulation observed over the Iberian Peninsula for the 1990-98 period, we have characterized the daily circulation by means of a set of indices associated with the direction and vorticity of the geostrophic flow.We analyse the synoptic characteristics of the types of circulation obtained, gaining statistical information about the most frequent basic situations for the annual and seasonal periods. We show how the anticyclone situation (A) predominates in winter, spring and autumn, whereas in summer the most frequent weather corresponds to pure easterly weather (E) followed by cyclonic weather (C).We report the findings of a comparative study between the frequencies of the daily values of the dominant types of circulation and the corresponding daily values of the number of cloud-to-ground flashes over the Iberian Peninsula between 1992 and 1994. Each synoptic situation is described by a set of characteristics that explains the development of the convective processes. A high degree of correspondence was obtained, especially for the months between May and October, in which major storm activity occurs (Pearson correlation coefficient: 0.76). All the results show that convective processes, which generate storm activity, can be appropriately explained in terms of the variability of a small number of general synoptic situations.

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ABSTRACT:The aim of this study is to evaluate the possible associations between daily hospital admissions for cardiovascular, respiratory and digestive diseases in Salamanca (Spain) and weather conditions during the winters of 1995-2005. An objective daily air mass classification was performed by means of statistical analysis of ground-level meteorological data. This afforded seven main circulation weather types (CWTs) for the cold period, and the frequency distributions of these types and their meteorological characteristics were analysed.A summary of the main characteristics of the hospital admission series and their distribution over the 10 years studied, together with the frequency distributions of the different diseases classified by ages, the average number of the hospital admissions for each day of week, type of disease and sex, is given. In addition, a comparison between air mass classification and hospital admissions was made using an admission index (AI), for each disease. Significant increases in hospital admissions for the cardiovascular AI were evident 24-48 h after a day characterized by an anticyclonic air mass, 4-5 days after a day characterized by a westerly air mass and 6-7 days after an easterly flow. For the respiratory AI, an increase was observed 2-3 days after a cyclonic situation, 4 days after a northeasterly situation, while for days characterized by southwesterly air masses no delay was observed. These results indicate that the effects of weather conditions on hospital admissions tend to occur some days after exposure.

This study was carried out in the region of Castile and Leon, Spain, from 1980 to 1998 and analyzes the relationship between the number of monthly deaths caused by cardiovascular, respiratory and digestive diseases and three meteorological variables: temperature, pressure and humidity. One of the innovations in this study is the application of principal component analysis in a way that differs from its usual application: one single series representing the whole region was constructed for each meteorological variable from the series of eight weather stations. Annual and seasonal mortality trends were also studied. Cardiovascular diseases are the leading cause of death in Castile and Leon. The mortality related to cardiovascular, respiratory and digestive systems shows a statistically significant rising trend across the study period (an annual increase of 6, 16 and 4 per thousand, respectively). The pressure at which mortality is lowest is approximately the same for all causes of death (about 915 hPa), but temperature values vary greatly (16.8-19.7 degrees C for the mean, 10.9-18.1 degrees C for the minimum, and 24.1-27.2 degrees C for the maximum temperature). The most comfortable temperatures for patients with cardiovascular diseases (16.8 degrees C) are apparently lower than those for patients with respiratory diseases (18.1 degrees C), which are, in turn, lower than in the case of diseases of the digestive system (19.7 degrees C). Finally, the optimal humidity for patients with respiratory diseases is the lowest (24%) among the diseases, and the highest (51%) corresponds to diseases of the digestive system, while the optimal relative humidity for the cardiovascular system is 45%.