CHANGE OF CHARACTERISTICS OF HEATING PERIOD IN ULYANOVSK FOR 2000-2020

In this paper we considered the Ulyanovsk heating period characteristics in the period from 2000 to 2020 and their changes. Daily meteorological observations of the Ulyanovsk Civil Aviation Meteorological Station were used as the initial data. Statistical analysis showed that during the period under review, there was a noticeable warming of the cold part of the year, as a result of which the fuel consumption index decreased. It is revealed that the duration of the heating period increases due to its later finish in the spring.

Stable isotope composition of precipitation as signal of possible climate change: the case of the mountain Učka (Northern Adriatic, Croatia)

<p>The highest average annual rainfall in Croatia is in the Northern Adriatic, with some parts of the region receiving more than 2000 mm per year. Characteristics of the region’s weather are periods of intense rain alternating with dry periods in which the amount of precipitation can be negligible for more than a month. The area's water supply relies on karst groundwater sources that are primarily fed by Mediterranean precipitation. The aforementioned precipitation regime results in high groundwater yields in the cold part of the hydrological year and substantially decreased water quantities in the summer months. Under such specific conditions, it is of considerable importance to find out about the potential for climate change in order to ensure timely adjustment of the management and use of natural sources of water.</p><p>We present a comparison of the isotopic composition of precipitation collected on the mountain Učka in periods 2008-2011 and 2019-2020. Rain gauges were located on a vertical gradient from sea level up to nearly 1400 m. Unlike the isotopic altitude effect that did not change significantly compared to the one reported for the first period (Roller-Lutz et al, 2013), the weighted means of isotopic values were more positive in the second period.  For the cold part of the hydrological year, local meteoric water line has recently moved to higher values, indicating the sources of precipitation from drier Mediterranean regions. Local meteoric water line for the warm part of the last hydrological year, indicates presence of increased evaporation and thus confirms lower precipitation amounts.</p><p> </p><p>Roller-Lutz Zvjezdana, Mance Diana, Hunjak Tamara, Lutz Hans O. (2013) On the isotopic altitude effect of precipitation in the Northern Adriatic (Croatia), Isotopes in Hydrology, Marine Ecosystems and Climate Change Studies. Vol. I. Proceedings of an International Symposium</p><p> </p><p>This work was supported by the University of Rijeka as part of the research project uniri-pr-prirod-19-24.</p>

Changes in the extreme air temperature in Czech Republic

This study is focused on air temperature in Czech Republic in relation to selected climatological indices for extreme hot and extreme cold days for the period 1961- 2017. The number of summer days (SU) and number of tropical days (SU30) have been chosen as the indicators of extreme hot days. For the indicators of extreme cold days, the number of frost days (FD) and number of icing days (ID) have been analyzed. The analyses are based on the daily data for air temperature measured at eight meteorological stations situated at the regions with different geographical and climate conditions. The data are freely available from the website of the Czech Hydrometeorological Institute. The results of the study show negative trend of extreme cold events and positive trend of extreme hot temperatures. With a few exceptions, the trend is statistically significant at p=0.05. The trend values for the indicators of cold days are higher than those for the indicators of warm days. The results show a faster change in air temperature for the cold part of the year

IMPACT OF LOW LATITUDES ON THE CLIMATIC CONDITIONS IN THE MAIN SIBERIAN RIVERS CATCHMENT AREA

It was previously shown that atmospheric and oceanic transports of heat and moisture play an important role in the development of Arctic warming, and sea surface temperature anomalies at low latitudes have a significant effect on the formation of these transports. Atmospheric circulation, transferring heat, moisture and precipitation, also affects the climatic conditions in the catchment areas of 3 main Siberian rivers Ob, Yenisei and Lena with runoff that it about half of the average annual inflow of river waters into the Arctic Ocean. According to the reanalyses and data arrays for the period 1979-2019 air temperature and precipitation in the catchment areas of Ob, Lena and Yenisei are rising. The greatest increase in precipitation was noted in the spring months. The spring months (March and April) also have a maximum positive air temperature trend. To assess the effect of low latitudes on changes in climatic conditions in the catchment areas reanalysis data ERA5, HadISST, precipitation gridded data of the GPCC project were used. The indexes of zonal, meridional and general circulation were calculated based on the mean monthly surface air temperature at the nodes of the geographic grid in the Northern Hemisphere. To determine the connections between the indexes and climatic parameters the methods of multivariate cross-correlation analysis were used. It was defined that zonal atmospheric transports have a significant impact on climatic conditions most of all in the cold part of the year, especially in November and March. In summer amplification of zonal circulation is accompanied by a decrease in air temperature in the catchment areas, but meridional transports enhance the air temperature. The greatest influence of meridional transport was observed in spring and summer. The climatic change in low latitudes has the greatest impact in autumn on meridional transport in spring and on zonal transport in the cold part of the year, especially in March, with time lag of 2 years. The influence of low latitudes on the climatic conditions in the catchment areas is presented in the form of correlation graphs between climatic parameters and indexes of circulation on the generalizing diagram.

Varijabilnost padalina u Hvaru i Crikvenici

The study analyses the precipitation variability in Hvar and Crikvenica in the period from 1931 to 1990. These stations have a maritime type of the annual course of precipitation. The minimum value of the precipitation variability in Hvar is in autumn, in November, while the secondary minimum of the variability is in spring, in April. The primary maximum of variability is in summer, most often in July, while the secondary maximum is in March. In Crikvenica the minimum values of the precipitation variability in April and November are even, and the same is true for the maximum values of the variability in September and March. The value of the annual precipitation variability is higher in Crikvenica than in Hvar although Crikvenica has higher amount of precipitation. The location of the stations included in this research is relevant. In Crikvenica the variability is higher in autumn and winter. Monthly values of the mean relative variability coincide in the cold part of the year when the variability is only slightly higher in Crikvenica, while in the warm part of the year, with the exception of September, the variability in Hvar is significantly higher.