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Climatology

Volume XVII |

Considerations on the Influence of Micro Urban Heat Islands to the Temperature – Humidity Index During July 2017 in Craiova City Centre

Abstract: According to the National Administration of Meteorology, July 2017 was the hottest July months in the last decade, with one of the longest period with canicular temperatures in the last decades, too. In many regions of Romania, including Oltenia and Craiova city, too, yellow or orange code warning had to be announced. To determine real thermal discomfort sensation felt by the population of Craiova city, experimental research concerning micrometeorological measurements of the real temperature and relative humidity that contribute to the local Temperature – Humidity Index (THI) value was performed. According to the experimental research results, confirmed by using thermovision too, in Craiova city centre, five micro urban heat islands (MUHI) were identified. For three streets and a public square, despite the small mean value of relative humidity, due to the temperature’s high mean value, in these hot spots the THI mean average was 89.97, and for this thermal discomfort sensation, special protection measures would be needed. The same air micrometeorological parameters in these four hot spots were compared with the ones recorded in English Park, where due to vegetation and trees’ shadow, the THI average was 84.11, thus the real thermal discomfort sensation would have made necessary adequate protection measures. In order to study the intensity and spatial pattern of the MUHI, thermal infrared remote sensing (thermovision) was used to observe the surface of MUHI as a complementary indicator of the thermal discomfort sensation with in MUHI. The paper presents relevant interdependence relationships between the near surface air temperatures and pavement/ buildings surface temperatures that have been found for MUHI in Craiova’s city centre. The paper proposes practical methods that could be used to decrease the pavements’ and buildings’ walls temperatures, thus contributing to the decrease of THI in the MUHI within Craiova city centre.

Volume XVII |

The analysis of relationship between microclimate and microbial carbon-dioxide production in the soils of the Tapolca and Gömör-Tornai karst terrains, Hungary

Abstract: In the karst areas, the epikarst system is a very sensitive environment, due to its position at the interface between soil and vadose zone. The epikarst is a weathered zone that develops as a result of both abiotic and biotic processes. In this paper we present the result of the complex investigations of epikarst zone which overlap dolines within two typical karst areas (Gömör-Torna and Tapolca) from Hungary, based on multicriteria analysis techniques (microbiological activity assessed as biomass amount and CO2 production, seasonality of air and soil microclimate, slope orientation and exposition), in order to reveal control factors of karst processes, the territorial and local distinctions of karst dissolution that occur in the epikarst zone. The data were compared, taking into account the human activities’ impact on both sampled study areas. After four years of monitoring, the results show that there are significant seasonal and diurnal variations of physical, chemical and biotic parameters of soil that cover and affect the epikarst zone. Spatial variations of these parameters were recorded as well.

Volume XVI |

Monitoring drought status using precipitation factor: a case study of Jaisalmer Meteorological Station in Raja-sthan, India

Abstract: Drought is a climatic phenomenon induced by a deficiency in moisture due to the decrease in precipitation amount over of a region for a given time period. Thus for evaluating drought, long-time data series are necessary. In the present study on the basis of precipitation amounts registered at Jaisalmer station in Rajasthan state India, meteorological drought indices such as the Standard Index of Annual Precipi-tation (SIAP), Standardized Precipitation Index (SPI), Precipi-tation Anomaly Index (RAI) and Deciles Index (DI) have been computed in order to monitor the drought status. Then Kol-mogorov-Smirnova and Shapiro-Wilk tests were applied to examine the normality of raw data. Sequential Mann–Kendall test (SQ-MK test) was applied for determining trends. The results show no statistically significant trend, but there were points of negative mutation in annual precipitation. Drought monitoring, based on the four mentioned indices, indicate SIAP index as the most appropriate for the study area as its coefficient of correlation is close to 1.

Volume XVI |

Considerations upon extreme temperatures on Romanian territory

Abstract: In this article we analyse the evolution in time of extreme temperatures significant for Romania with a focus on absolute extreme temperatures recorded on the overall present territory. After thoroughly investigating the credible sources referenced at the end of the paper, we present in chronological order the records for absolute minimum temperatures, and absolute maximum temperatures which were measured at the meteorological stations on the present territory of Romania, according to the availability of the data, i.e. the last two decades of the 19th century up until 2017.  We classify and discuss the sources of climatological data in the form of minimum and maximum temperatures. The measurements of meteorological parameters on the current national territory were recorded since 1770 at Iași (cf. Dissescu 1931 and also http://www.meteoromania.ro/anm2/despre-noi/istoric/ – page in Romanian as of 30.03.2017). For a systematic approach with credible data, at least another century passed, until Ștefan Hepites (1851-1922) founded in 1884 in Bucharest the Central Meteorological Institute of Romania (I.M.C. in Romanian) (Dissescu, 1931 and cf. the ANM web page quoted earlier). The newly created Institute did not include the meteorological stations which were present at that time in Transylvania, but only the ones on the official Romanian territory of 1859-1918 made up of Moldavia and Wallachia. This paper argues in favour of the process of global warming (GW) and its effects upon the evolution of extreme temperature values in a certain time interval. The conclusions stemming from the investigation of the dataset in this paper should provide a helpful and necessary point of departure in subsequent research of climatologists in their quest of identifying the correct model of future climate. Our article should be regarded as part of a series of analyses of the variability of the climate in Romania, the recent influence of global warming on it and on certain climatological parameters in particular.

Volume XVI |

Analysis of the Mean of Daily Maximum Temperature within the Romanian Plain (1961-2015)

Abstract: The present study aims at rendering the characteristics of the means of the daily maximum temperature at monthly, seasonal and annual level within the Romanian Plain, as well as their trends. The time series cover a 55-year period (1961-2015) and data come from 8 meteorological stations. In order to assess the distribution of the data, there were calculated two coefficients (Skewness – S and Kurtosis – K) and also applied the Kolmogorov-Smirnov test for normal distribution. The positive S values and negative K values indicate that the distribution is not symmetrical but, taking into account that the values are quite close to 0, we may assume, it is not far from normal. The KS test also indicates a normal distribution. Homogeneity of the annual temperatures was tested by means of Pettitt test, Standard Normal Homogeneity Test (SNTH) and t test, which emphasized that the change point was registered before 2000. At three stations (D.T. Severin, Bechet, Buzău) all three applied tests indicated the same year 1988, respectively 1989 as break point, while at the other stations, it is the same year according to SNHT and T test, and a different one based on MWP. Based on Mann-Kendall test and Sen’s slope estimation, there were emphasized temperature trends and their statistical significance. The highest temperature increase and upward trend was registered for mean annual and mean summer values (0.001 level of significance within the entire region). However, except for autumn, which is generally characterized by statistically insignificant negative trends, all the other seasons display significant upward trends. At monthly level, only the summer months registered upwards trends within the entire plain (level of significance oscillating between 0.05 and 0.001), while in autumn months there were not registered any statistically significant trends.