C. J. Lolis

Spatial covariability of the climatic parameters in the Greek area

In this work, 12 monthly climatic parameters of 49 Meteorological stations in Greece are classified according to their spatial covariability, in order to define groups of climatic elements having the same, characteristic, spatial distribution. The grouping of the parameters is achieved objectively by using the method of factor analysis. The analysis is applied to the winter months of January and February and to the summer months of July and August. In winter, the parameters are classified into four groups as follows: (i) maximum, mean and minimum temperature and, negatively, pressure and number of frost days; (ii) wind and, negatively, diurnal temperature range; (iii) precipitation; and (iv) cloudiness and relative humidity. In summer, the parameters are classified into three groups, namely: (i) precipitation, cloudiness and, negatively, minimum temperature; (ii) maximum and mean temperature, relative humidity; and (iii) wind. From the above groups the most interesting is group (i) of summer, as its parameters belong to different groups in winter. Finally, the study of the spatial distribution of the above groups showed that some depend on latitude, others on the continentality and others on the leeward or windward character of the various areas. Copyright

On the relation between seasonal synoptic circulation types and spatial air quality characteristics in Athens, Greece.

Abstract The impact of weather on air pollution was examined and evaluated for the city of Athens, Greece. We used an objectively defined synoptic classification scheme consisting of six summer and eight winter circulation types. This scheme was established using a combination of both factor and cluster analysis during 1954–1999. Surface and isobaric levels of 850 hPa data were used. Factor analysis combined with cluster analysis was used to derive circulation types based on surface meteorological data for the period 1954–1999 in Athens and on surface pressure grid data. The city was divided into three sectors according to the financial and social activities of the residents. To examine the spatial characteristics of pollutant concentrations over Athens for each synoptic type, the synoptic circulation types were then correlated with both gaseous and particulate pollutant concentrations measured in each sector between 1983 and 1999. Finally, extreme and severe episodic events were studied in terms of their meteorological and synoptic characteristics.

Effect of meteorological parameters on acute laryngitis in adults.

The aim of this study was to investigate the influence of weather conditions on the frequency of acute laryngitis in adults. The medical records of 825 patients with a diagnosis of acute laryngitis obtained over a 5-year period were reviewed. Meteorological data reviewed included the daily values of 13 parameters. The monthly distribution of the disease was assessed. In addition, a detailed 2-part statistical analysis was performed as follows: ( i ) the relationship between each meteorological parameter and the frequency of the disease was investigated, using contingency tables; and ( ii ) the 1825-day period was divided into 8 groups characterized by similar weather, using factor and cluster analysis, and the disease frequency in each group was assessed. Our observations were as follows: 1. Meteorological parameters, such as low temperature, low diurnal temperature range, low atmospheric pressure and low mean water vapor pressure, were associated with an increased occurrence of acute laryngitis. 2. Significant changes in maximum temperature or a significant drop in atmospheric pressure, as compared to the previous days conditions, favored new cases of the disease. 3. The cold period of the year was associated with an almost two-fold increase in the frequency of disease cases, which peaked in March and reaching a minimum during August. 4. The peak frequency of cases was associated with winter weather conditions, which were characterized by high humidity readings. In conclusion, meteorological parameters, and their variation and covariation, are strongly associated with acute laryngitis in adults.

Intra-annual variation of atmospheric static stability in the Mediterranean region: a 60-year climatology

The seasonal characteristics of atmospheric static stability in the Mediterranean region are examined, for the 60-year period 1948–2007 and for the four 15-year sub-periods 1948–1962, 1963–1977, 1978–1992 and 1993–2007. S-Mode and T-Mode Factor Analysis are applied to the mean 5-day values of K static stability index over the Mediterranean region. Three dominant modes are revealed for both, the intra-annual variation and the spatial distribution of K-index. It is found that these modes are connected to the seasonal characteristics of the main atmospheric circulation systems affecting the region and the thermal properties of the Earth’s surface (land or sea). The differences among the results of the four sub-periods partially reflect the inter-decadal variations of the strength of the above factors.

Weather conditions and Bell's palsy: five-year study and review of the literature

BackgroundClimatic or meteorological condition changes have been implicated in the pathogenesis of Bells palsy (BP). We evaluate the influence of meteorological parameters, such as temperature, humidity, and atmospheric pressure, and their variation and covariation on the incidence of BP and present a review of the literature on the effect of meteorological conditions on facial nerve function.MethodsA total of 171 cases of BP admitted to our Department over a five-year period were studied. The meteorological database included daily values of 13 distinct parameters recorded at the meteorological station of the University of Ioannina during this period. A relationship between each meteorological variable and the incidence of BP was investigated by applying (Χ2) test on data from 13 contingency tables. In addition, the influence of different weather types on the incidence of BP was also investigated. For this purpose Cluster Analysis was used to create eight clusters (weather types) for the Ioannina prefecture and (Χ2) test was applied on the contingency tables consisting of the days of BP cases for each cluster.ResultsNo significant correlation was found either between BP and each distinct meteorological parameter or between BP and any specific weather.ConclusionsMeteorological conditions, such as those dominating in the Northwestern Greece, and/or their changes have little effect on the incidence of BP. Multicenter studies taking into account atmospheric pollution, and climatic differences between countries, are necessary to scrutinize the environmental effects on facial nerve function.

Weather conditions and sudden sensorineural hearing loss

BackgroundClimatic or meteorological condition changes have been implicated in the pathogenesis of Idiopathic Sudden Sensorineural Hearing Loss (ISSHL). We investigated the seasonal distribution of ISSHL and evaluated the influence of meteorological parameters (such as temperature, humidity, and atmospheric pressure), their variation and covariation on the incidence of the disease.MethodsA total of 82 cases of ISSHL, admitted to our department over a five-year period, were enrolled in the study. Seasonal distribution of the disease was investigated by dividing the year in four seasons. Meteorological data included daily values of 13 distinct parameters recorded at the meteorological station of the University of Ioannina during this period. A relationship between each meteorological variable and the incidence of ISSHL was investigated by applying (χ2) test on data from 13 contingency tables as well as by using logistic regression and t-test approaches. In addition, the influence of different weather types on the incidence of ISSHL was investigated using Cluster Analysis in order to create eight clusters (weather types) characteristic for the prefecture of Ioannina.ResultsThe results of the study could not indicate any seasonal distribution of the disease. The incidence of ISSHL could not be significantly correlated either to any distinct meteorological parameter or to any specific weather type.ConclusionsMeteorological conditions, such as those dominating in the Northwestern Greece, and/or their changes, have no proven effect on the incidence of ISSHL.

Atmospheric Circulation Characteristics Associated with high Static Instability Conditions Over the Athens Region

The main atmospheric circulation characteristics associated with high static instability conditions over the Athens region are examined for the period 1974–2004. The data used consist of daily (12UTC) values of: (1) 850, 700 and 500 hPa air temperature and dew point from radiosonde measurements at the Athens Hellinikon airport (BADC) and (2) 2.5 × 2.5 grid point 500 and 1,000 hPa geopotential height over the Mediterranean region (NCEP/NCAR), for the period 1974–2004. The stability index K (K-index) is calculated from the radiosonde measurements. Then, 5 % of the days (280 days) with the highest K values (highest instability days) are selected for the cold (16/10–15/4) and the warm (16/4–15/10) period of the year. For these days, a classification is applied to the geopotential height spatial distributions, by using Factor Analysis and K-means Cluster Analysis. The selected days are classified into nine clusters for the cold period and five clusters for the warm period. The mean 500 and 1,000 hPa geopotential height patterns are constructed for the days classified into each one of the clusters. According to the results, the clusters correspond to distinct circulation types associated with high instability conditions over the Athens region.

Rainfall Measurements Due to Radio Frequency Signal Attenuation at 2 GHz

In this paper we present an experimental validated system for measuring rainfall due to radio frequency (RF) signal attenuation at 2 GHz. Measurements took place in Ioannina, NW Greece, starting in April 2015 and lasting for twelve months. The primary acquired extensive results have shown reliable and accurate measurements for rainfall amounts smaller than 1 mm for 5 min periods. The very important innovation is that this paper presents significant earth-to-earth measurements due to rainfall attenuation (at 2 GHz) in order to act as a map for future investigation and as a prior knowledge for the behavior of other systems operating at frequencies around S-band.

Seasonal Variability of Total Cloud Cover in the Mediterranean Region for the Period 1948–2014

The seasonal variability of total cloud cover in the Mediterranean region is studied, using NCEP/NCAR daily grid point data. The mean day to day intra-annual variations of total cloud cover during the hydrological year (1 October–30 September) are extracted for the 66-year period 1948–2014. A dimensionality reduction method is applied on the 324 time series and three main modes of seasonal variation of cloud cover over the Mediterranean region are found. The first one is simple, characterized by a maximum in winter and a minimum in summer, prevailing mainly over the sea. The second one is double showing maxima in early autumn and late spring and minima in late summer and winter and prevails over SW Europe and NW Africa inland regions. Finally, the third one shows a maximum in June and a minimum in October and prevails over the eastern part of central Europe. The main characteristics of these modes are attributed to the seasonal variation of the various thermal and dynamical factors affecting the region. An examination of the seasonal variability of cloud cover in the above core regions during sub-periods of the total period 1948–2014 reveals some long-term changes during the last 66 years.

Deucalion: Modern Educational Tools for Precaution Measures During Extreme Weather Events

The prevention and confrontation of natural hazards during extreme weather conditions constitute an educational subject usually provided by bodies such as the meteorological service or environmental education, health education and educational mobility programs. In such actions, Information and Communication Technologies (ICT) have a dominant role, since students use them widely, not only in the educational process but also in their daily lives. A modern approach to the pedagogical use of ICT is the use of digital learning objects. Learning objects are described as self-standing resources of learning content that include or indicate learning objectives. The Deucalion project proposes the use of digital learning objects for natural disaster education and especially for disasters caused by atmospheric phenomena. The learning objects include interactive virtual and multimedia environments, as well as educational games. The learning objects refer to atmospheric phenomena such as rain, snow, hail, frost, wind, etc. Their usage is carried out through meaningful teaching interventions and educational scenarios. Their inclusion in the educational process is proposed either by incorporating them into the curriculum, or in environmental education and health education programs.