14. starptautiskÄ konference 2012 - Latvijas JÅ«ras akadÄmija

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Air temperature, deg CProceedings of 14th International conference „Maritime Transport and Infrastructure - 2012”987654y = 0.0031x + 0.214531780 1810 1840 1870 1900 1930 1960 1990 2020YearsFig. 2 Average air temperature changes in Riga at time period from 1795 to 2011Table 1The general tendency of air temperature changes in Riga, at value of o C/100 years for different periodsTime period years 1795-2011 1840-2011 1900-2011 1960-2011Tendency of airtemperature changes,C/100 years0.31 0.69 1.37 3.732. Levels of waterLevels of water are being influenced by astronomical conditions, fresh water balance, unevenatmospheric pressure, and wind /water density mutual rates. Water level changes in Baltic Sea arebeing under direct impact from endogenous fresh water flow fluctuations, changes of atmosphericpressure and winds; there are some direct relations of such changes with melting of ice cover andEarth crust’s vertical shifts. This title covers annual average changes of the levels of water in Ventspilsand Daugavgriva at time period from 1873 to 1968. Both locations are characterized by clear tendencyof water level growth – in the Daugavariver the level of water has grown by 20.5 cm per 100 years, inVentspils water level has grown by 4.4 cm/100 years (Fig. 5).The interest sparking finding is that the average speed (rate) of water level growth in bothlocations is quite different. This difference could be explained by Earth crust’s lithospheric verticalshifts in Baltic region. There are no significant vertical lithospheric shifts in Daugavgriva, but averagevertical lithospheric movement rate in Ventspils is about 0.6-1.0 mm/year, providing 6-10 cm/100years [7]. The assumption is that water level fluctuations in Daugavgriva are in direct relation with thetrends of Ocean water level, in turn, Ventspils indicators are under impact from Earth crust’slithospheric vertical shifts.124
Water level (+/-), centimetreProceedings of 14th International conference „Maritime Transport and Infrastructure - 2012”20100-10-20-301870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970YearsVentspils Daugavgriva Vent.-Daug. Linear (Vent.-Daug.)Fig. 3 Changes of the level of water in Ventspils and Daugavgriva (river basin) at time period of last centuriesAt times of Glacial era (~12000 years before), the oceanic water levelwas approximately 60meters lower than nowadays, and average water level growth rate until now is 50 cm/100 years [8].Making the comparison of water level growth rate at time period of last centuries and after the lastGlacial era, we can assume, that current growth rate is at least three times less than latter. It means,that general ice melting rate is considerably decreased and there is no ground for a statement, that lastcenturies are associated with the intensive water level growth.ConclusionsUpon the analysing of air temperature and water level changes in Latvian coastal area, in acontext with other associated researches, we can conclude as follows:- The analysis of air temperature data in different profiles leads to the conclusion, that naturehas short term, middle term and long term climatic conditions cyclic variations;- The rate of water levels raise at time period of several previous centuries is three times lessthan this rate at period after the final stage of last Glacial era;- The process of global warming has started after the final stage of Glacial era and isprogressing up to nowadays, and there is no ground for statement, that the process has beingfacilitated.References1. V. Berzinsh. Hydrology. Ecosystem of the Gulf of Riga between 1920.and 1990. E. Ojaveer (ed.), EstonianAcademy Publishers, Tallinn, 1995. - 7-31p.2. Месячные выводы метеорологических данных за отдельные годы. Латвийская ССР, Частъ I,Температура воздуха., Ред. Я. Скрастинъш, Рига, 1952.- 297 с.3. Метеорологический ежемесячник. вып. 5. ч. 2, Рига, Обнинск, 1952. – 1990. – 30 - 40 с.4. Water level, currents, water temperature, ice, water salinity. Basic hydrological characteristics., Vol. 1, Iss. 3.N. Arsenyeva (ed.), Riga, 1972. - 364 с. (in Russian)5. O. Āboltiņš.No leduslaikmeta līdz globālajai sasilšanai. Dabas vides pagātne un tagadne Latvijā. LUAkadēmiskais apgāds. Rīga, 2010. - 128 lpp.6. V. Bērziņš.Dažas okeanogrāfisko parametru dinamikas īpatnības Latvijas jurisdikcijas ārējos ūdeņosmūsdienās. LU 68.zinātniskā konference, Rīga, 19.02.2010. Klimata mainība un ūdeņi. KALME. Rakstukrājums, 2010. - 16-24. lpp.7. В.К. Гуделис, Е.М. Емельянова. Геология Балтийского моря, Вильнюс, 1975. -380 с.8. P. Mälkki, R. Tamsalu. Physical features of the Baltic Sea.- Finnish Marine Research, No. 252, Helsinki,1985. - 110 pp.125
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