Abstract: The subject of research refers to potential causative-effective connection between processes on the sun and the largest forest fires in Deliblatska peščara. The four greatest forest fires in Deliblatska peščara in the period 1948-2009 were in 1973, 1990, 1996 and 2007. The analysis of solar activity, especially the solar wind data and the analysis of the fire events were used in the research of the possibility of mutual connection. There are no enough data for the fire that occurred in 1973 on the basis of which the connection with processes on the sun would be determined. The fire from 1990 developed in the conditions of intensive solar activity and it was probably caused by the solar wind. There are some indications that the solar wind from energetic region 7981 caused the largest forest fire in Deliblatska peščara in 1996. For fire that occurred in 2007, the energy source (coronary hole CH279) was determined, as well as the moving of the solar wind particles. During the investigated fires the phenomena characterising fires caused by solar wind were recorded, such as frequent wind direction changes and appearance of fire on different locations at the same time. The statistical analysis of the number of fires in Deliblatska peščara and AMO also indicated the anti-phase connection between these events. Even though the obtained results have shown the signal of the connection between charged particles and initial phase of fire, the laboratory testing is necessary to prove the mentioned hypothesis.

Abstract: The study presents the observed variability and changes in precipitation regime in the Danube river lower basin, which is situated along both sides of the border between Bulgaria and Romania. The research is based on monthly precipitation totals recorded at 22 meteorological stations from Bulgaria and Romania. The investigated period is 1961-2007 out of which two reference periods are considered, the last 30 years (1978-2007) and the usually used WMO reference for the contemporary climate (1961-1990). The main objective of the study is to give actual information about precipitation variability in the region in the context of global climate change. The results of the work point out on some characteristics of extreme precipitation events in the region – drought and high precipitation, and on the role of natural mechanisms for precipitation variability. Based on the statistical methods we have used, the results can be summarized as follows: – Summer precipitation represents 30-35% of annual precipitation total followed by spring precipitation with about 25-28% of annual values. Autumn precipitation is between 22-24% of annual values in most of the stations. Winter precipitation represents about 20% of annual precipitation; – The wet periods have been observed at the end of the 1960’s and at the beginning of the 1970’s; – The intensive drought from 1983 to 1993 has been confirmed by calculating the precipitation indices like as Rainfall Anomaly Index and Cumulative Anomaly Index. The driest year during the investigated period was 2000; – Increasing occurrence of extremely wet months has been observed since 2002.

Abstract: The present paper deals with the conditions related to spring arrival in Oltenia between 2000 and 2010. A first general evaluation may be achieved by comparing the mean general indexes for the entire region of Oltenia for each spring, which are calculated as a mean of the indexes of spring arrival for all the meteorological stations from Oltenia, including the mountainous area.Out of the 11 analysed years, the lowest value was 171.1°C, registered in the spring of 2003, which followed the coldest winter (2002-2003) of the studied interval (Bogdan, Marinică, Marinică, 2010); the highest value reached 460.7°C and it was registered in the spring of 2002 that followed a warm winter, 2001-2002, the general mean of which is on the 9th place in the increasing hierarchy of the general temperature means for winter during the analysed interval. The general mean of the index for the 11 analysed years is 366.0°C with a positive percentage deviation of 43.2%, which, according to a Hellmann’s type of criterion established by us, emphasizes that springs were early (E) during the entire period. The negative deviation of the latest spring (2003) was of -29.1.1%, which means a late spring (L). The second value of the index was 262.9°C, which means a normal spring. The positive deviation of this general mean of the spring arrival index for the spring in question (2003) reached 7.1%, which means a normal spring, in fact, the single normal spring of the entire interval. For Oltenia, as well as for the entire country, the decade 2000-2010 was warm. It stands out through – the warmest winters, which also registered the highest frequency, the earliest springs, the hottest summers with the more extended dog days’ periods, the exceeding of certain absolute thermal maximum values in the country, some of them considered real “climatic thresholds”, all induced by the climate variation limits of the end of the 20th century and the beginning of the 21st century. The predominance of early springs represent a proof of the regional climatic changes during this interval.

Abstract: Understanding the dryness and drought phenomena is fundamental in explaining the landscape features and the rational use of water resources in a region. The authors aim to assess the climatic water deficit (WD) in one of the most sensitive regions in Romania in terms of aridity: Southern Oltenia. Defining and characterizing the intense aridity was done based on the Thornthwaite method under a multi-annual regime (1961-2007) and during the growing season (April-October) in order to reveal the climate suitability for human activity and the optimum conditions for the main crops. In southern Oltenia the Thornthwaite aridity index values (Iar-TH) (%) defines an arid area, increasing from north to south and south-west from 40-45% to 50%. The highest values displaying a pronounced aridity (Iar-TH ≥ 50%) cover a significant part of the Blahniţa Plain, Desnăţui Plain, Southern Romanaţi Plain (Dăbuleni Field), the Jiu Valley and the entire Danube Plain (about 65% of the entire surface).

Abstract: Temperature-humidity index, also known as thermal comfort index, represents an extremely used index in mass-media nowadays; it renders an apparent temperature, namely the temperature felt by human body that cools slower at higher values of the relative humidity due to the reduction of the evaporation rate. THI is calculated on the base of several formulas, which corroborate air temperature and relative humidity, the critical threshold being 80. By analysing the statistical date supplied by the Regional Meteorological Center Craiova, it comes out that the years with the highest number of days with THI values above 80 are 2000, 2001, and 2007 for the entire studied territory, when, during summer, the region was affected by numerous heat waves, which led to the frequent exceeding of the 40°C value. The most affected area is located in the central-southern and eastern parts of the Oltenia Plain – 51 days with THI > 80 at Caracal in 2000, 47 days with THI > 80 at Bechet in 2001, and 41 days with THI > 80 at Băileşti in 2007. Regarding the monthly distribution, the most problematic months are, of course, July and August, when it is favoured the penetration of certain extremely hot air masses from northern Africa, as well as thermal convection. During the analysed decade, the highest monthly number of days with values above the threshold was registered at Caracal in August 2000 – 23, at Bechet in August 2001 – 25, and at Băileşti in July 2007 – 20. On the whole, in the 10 analysed years, we remark Băileşti – 76 days in July and 90 in August, Bechet – 84 days in July and 83 in August, and Calafat – 77, respectively 70 days. Increased values of THI mainly affect children and elderly people or those suffering of different diseases. At values lower than 70 of the THI, most of the people feel comfortable, at values comprised between 75 and 80, about half of the population feels thermal discomfort, while at values above 80, even if the discomfort sensation is not obvious, it is recommended to take adequate protection measures.