European Geographical Studies

3-7

Authors: Elizbar Sh. Elizbarashvili, Mariya E. Elizbarashvili, Shalva E. Elizbarashvili

The probabilities of the occurrence of individual hazardous weather phenomena and their complexes in the city of Tbilisi were studied: hot days, strong winds, heavy winds, fog, hail, blizzard. The most common of the phenomena under consideration are hot days. Even in spring and autumn their probability is quite high, and in summer it reaches 0.83. During the cold season, there is a high probability of fog. Strong winds occur at all times of the year. Their probability is not very high, but is characterized by a significant coefficient of aggressiveness. Hail is especially aggressive and occurs in the warm season. The likelihood of a snowstorm developing is negligible. Possible social and economic risks associated with these phenomena have been identified. Both social and economic risks are greatest from fog and strong winds. In winter, the economic risk from fog per incident can be more than 3.6 million US dollars, in the fall - more than 2.3 million US dollars. The social risk from strong winds is greatest in spring, although the risk is also significant in other seasons. The economic risk from strong winds in spring exceeds $2.6 million, and in winter exceeds $2 million. These phenomena occur several times throughout the year, so the economic risk can range from several to tens of millions of US dollars per year.

19-27

Authors: Thi Hoai Thu Trinh, Quang Van Nguyen

This study presents a comprehensive analysis of the tropopause height and temperature over the Vu Gia-Thu Bon river basin using multi GNSS-RO (Global Navigation Satellite System Radio Occultation) data. The findings reveal an average tropopause temperature and height are 195.341K (±0.166K) and 16.467 km (±0.079 km), respectively. Monthly fluctuations in tropopause altitude range from 15.898 km (min) in July 2008 to 17.208 km (max) in February 2010. The highest temperatures and lowest altitudes occur from May to September, while the lowest temperatures and highest altitudes are observed from October to April. Tropopause height varies from 15.848 km to 17.208 km, with deviations from the mean ranging from -0.079 km to 0.232 km. Tropopause temperature ranges from 192.647K to 197.797K, with deviations from the mean ranging from -0.166K to 1.893K. The multi-regression analysis shows a significant upward trend in both tropopause temperature and height from 2002 to 2017. The Tropopause temperature increases approximately by +0.2K with an average yearly increase of 0.013K, while the tropopause height shows an upward trend of about +0.1km with an average yearly increase of 0.008km. The annual and semi-annual periods display sinusoidal variations in both temperature and height, with the annual cycle showing a larger amplitude. These findings highlight the impact of global temperature change on troposphere dynamics, emphasizing the importance of monitoring and understanding these changes for climate forecasting in the Vu Gia-Thu Bon river basin.