Extreme Meteorological Phenomena Research Articles

Statistical modeling of hot spells and heat waves

20 Although hot spells and heat waves are considered extreme meteorological phenomena, 21 the statistical theory of extreme values has only rarely, if ever, been applied. To address 22 this shortcoming, we extend the point process approach to extreme value analysis to 23 model the frequency, duration, and intensity of hot spells. The annual frequency of hot 24 spells is modeled by a Poisson distribution, their length by a geometric distribution. To 25 account for the temporal dependence of daily maximum temperatures within a hot spell, 26 the excesses over a high threshold are modeled by a conditional generalized Pareto 27 distribution, whose scale parameter depends on the excess on the previous day. Requiring 28 only univariate extreme value theory, our proposed approach is simple enough to be 29 readily generalized to incorporate trends in hot spell characteristics. Through a heat wave 30 simulator, the statistical modeling of hots spells can be extended to apply to more full31 fledged heat waves, which are difficult to model directly. 32 Our statistical model for hot spells is fitted to time series of daily maximum 33 temperature during the summer heat wave season at Phoenix, AZ, USA, Fort Collins, CO, 34 USA, and Paris, France. Trends in the frequency, duration, and intensity of hot spells are 35 fitted as well. The heat wave simulator is used to convert any such trends into the 36 corresponding changes in the characteristics of heat waves. By being based at least in part 37 on extreme value theory, our proposed approach is demonstrated to be both more realistic 38 and more flexible than techniques heretofore applied to model hot spells and heat waves. 39 40

The influence of extreme meteorological phenomena on soil water regime of lowlands

The results of soil water storage monitoring performed at two sites of Rye Island region impacted by the Gabcikovo power station during years 1999–2004 shown the sensitivity of soil water content dynamics on the groundwater table level. Sensitivity of soil water storage of both sites was evaluated during the period of six years 1999–2004, in which the maximum precipitation was in year 1999 and the minimum in year 2003 (55% precipitationtotal of 1999) measured by meteorological station Gabcikovo. The soil water regime in Cilizska Radvan site was strongly influenced by the groundwater table and the soil water in the soil zone was recharged by the capillary rise and changes of soil water content even during the dry year 2003 was not significant. The Bac site, soil profile of which was not influenced by the deep groundwater table suffered from drought and was very sensitive to low precipitation total in the season 2003.

Insect identification expert system for forest protection

A forest can be considered as the major component of an ecosystem since it plays a critical role in soil protection, air quality, flood reduction, etc. It also plays a significant economic role for rural areas and for the national economy as a whole. The forest's health depends on many factors, such as biological, physical and anthropogenic. During recent decades, however, its health weakens continuously, because of the extreme meteorological phenomena and the increase of wildfires. As a consequence, the forest's sensitivity to secondary attacks by insects and fungus increases rapidly, since the latter find convenient expansion conditions. In this paper, an Expert System (ES) is described which identifies forest insects and proposes relevant treatment. It can identify more than forty distinct insects, either from some stage of their lifecycle or from the damage they cause to trees or from the findings that they leave in the forest. Once an insect identification is completed, the system can recommend an appropriate treatment, aiming at reducing spread of insects in the whole forest and at minimizing possible forest damage. The system is enhanced with photos and drawings that assist the user in the precise and quick identification of an insect. It can be used by unspecialised personnel or inexperienced users, such as forest owners. It can also be used in education or for training purposes, as a simple tutoring system. One major advantage of the ES is that it integrates, in, a single module, knowledge from diverse areas.

New Hydrological Approach for Environmental Protection and

Sustainable development means to protect and improve environment for future generation use. An effective protection requires action to limit global warming prevention catastrophic phenomena, such as severe floods or long-term droughts, and safeguarding people from their effects. Analyzing these phenomena evolution, the Romanian specialized institutes have adopted a new approach and developed a modern strategy, based on the latest hydrological theory available worldwide. According to this strategy, the Romanian authorities have begun to develop and implement new norms and technical regulations. These norms and technical regulations have fully changed the previous approach of the storm and runoff modelling in Romania. The paper presents the modeling methods of the design storm and overland runoff, which have been the base of the new norms and regulations (Romanian Standard SR 1846-2/2006, “National medium and long-term flood risk management strategy”, “Methodology for the establishment of the hydrographic basins exposed to floods”) and points out their implications in the environmental protection, water management field and in the fight against extreme meteorological phenomena such as severe floods and droughts.