{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,22]],"date-time":"2025-11-22T11:39:31Z","timestamp":1763811571460,"version":"3.40.5"},"reference-count":11,"publisher":"Geological Institute, Bulgarian Academy of Sciences","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Eng. Geol. and Hydrogeol."],"abstract":"<jats:p>This paper outlines time series data analysis from Varna tidal station (Black sea, Bulgaria), with the objective being to determine the influences of long-period and short-period tides. Observations series from monthly mean sea level values cover the period 1928-2023. The sea level measurements until 2013 were done with a mechanical float tide gauge. Since 2013 a radar tide gauge was installed in place of the mechanical one. A least squares linear regression model was applied for the analysis of monthly sea level data. As a result of the analysis, mean sea level, trend, seasonal and long-term tidal influences were established. In order to determine the influence of short-term tides, the method of least squares harmonic analysis was applied. In this method, observed sea level values are considered to be represented as a sum of tidal harmonics operating at previously known frequencies. The observation data include hourly values for the period 06.2013-12.2023. Some of the advantages of the applied method are that it allows to analyze series with interruptions in the observations, as well as assist to easily determine tides with close frequencies. From the analysis was determined the influence of: the annual and semi-annual tides, as well as about 68 short-period tides.<\/jats:p>","DOI":"10.52321\/igh.38.1.81","type":"journal-article","created":{"date-parts":[[2024,11,12]],"date-time":"2024-11-12T17:46:17Z","timestamp":1731433577000},"page":"81-88","source":"Crossref","is-referenced-by-count":1,"title":["Chronological changes in the Black Sea level at tide gauge station Varna 1928-2023"],"prefix":"10.52321","volume":"38","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-4801-1465","authenticated-orcid":false,"given":"Anton","family":"Ivanov","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5369-5921","authenticated-orcid":false,"given":"Nikolay","family":"Dimitrov","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"29796","published-online":{"date-parts":[[2024,11,12]]},"reference":[{"key":"ref0","unstructured":"Bondar, C. 2007. The Black Sea level variations and the river-sea interactions. Geo-Eco-Marina, 13\/2007, 43-50."},{"key":"ref1","unstructured":"Codiga, D.L. 2011. Unified Tidal Analysis and Prediction Using the UTideMatlab Functions. Technical Report 2011-01, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI., USA, 2011, 59 p., https:\/\/doi.org\/10.13140\/RG.2.1.3761.2008."},{"key":"ref2","doi-asserted-by":"publisher","unstructured":"Filipova-Marinova, M., D. Pavlov, K. Slavova. 2024. Paleoclimate changes and ecosystem responses of the Bulgarian Black Sea zone during the last 26000 years. Nature Conservation, 55, 201-248, https:\/\/doi.org\/10.3897\/natureconservation.55.121842.","DOI":"10.3897\/natureconservation.55.121842"},{"key":"ref3","doi-asserted-by":"publisher","unstructured":"Genov, I., K. Slavova, E. Koleva-Rekalova, T. Dog\u030can. 2024. Events and data concerning the Black Sea evolution after the last glacial peak: A comment. Geologica Balcanica, 53, 2, 11-28, https:\/\/doi.org\/10.52321\/GeolBalc.53.2.11.","DOI":"10.52321\/GeolBalc.53.2.11"},{"key":"ref4","doi-asserted-by":"publisher","unstructured":"Golyandina, N., E. Osipov. 2007. The \"Caterpillar\"-SSA method for analysis of time series with missing values. Journal of Statistical Planning and Inference, 137, 2642-2653, https:\/\/doi.org\/10.1016\/j.jspi.2006.05.014.","DOI":"10.1016\/j.jspi.2006.05.014"},{"key":"ref5","doi-asserted-by":"publisher","unstructured":"Ivanov, A., I. Georgiev, N. Dimitrov. 2020. Analysis of sea level data at Varna and Burgas tide gauge stations. SGEM, Volume 20, Book 2.2, 3-10, https:\/\/doi.org\/10.5593\/sgem2020\/2.2\/s09.001.","DOI":"10.5593\/sgem2020\/2.2\/s09.001"},{"key":"ref6","doi-asserted-by":"publisher","unstructured":"Ivanov, A. 2023. Harmonical Analysis of Sea Level Data at Varna Tide Gauge. SGEM 2023, book 2.1, 209-214, https:\/\/doi.org\/10.5593\/sgem2023\/2.1\/s09.26.","DOI":"10.5593\/sgem2023\/2.1\/s09.26"},{"key":"ref7","unstructured":"Medvedev, I.P. 2024. Variance of Short-Period Sea Level Oscillations in the Black Sea: Seasonal and Interannual Variations. Physical Oceanography, 31, 1, 59-70."},{"key":"ref8","unstructured":"Pugh, D. 1987. Tides, surges and mean sea level. John Wiley and son, 472 p."},{"key":"ref9","unstructured":"Schuerman, P. 1958. Manual of harmonic analysis and prediction of tide. Washington, United states government printing office 1958, 338 p."},{"key":"ref10","doi-asserted-by":"publisher","unstructured":"Thompson, K.R. 1980. An analysis of British monthly mean sea level, Geophysical Journal International, Royal astronomical Society, 63, 1, 57-73, https:\/\/doi.org\/10.1111\/j.1365-246X.1980.tb02610.x.","DOI":"10.1111\/j.1365-246X.1980.tb02610.x"}],"container-title":["Engineering Geology and Hydrogeology"],"original-title":[],"deposited":{"date-parts":[[2024,11,12]],"date-time":"2024-11-12T17:54:45Z","timestamp":1731434085000},"score":1,"resource":{"primary":{"URL":"https:\/\/igh-bg.com\/Vol\/Vol_38_2024\/6_Ivanov_Dimitrov-IGH-2024.pdf"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,11,12]]},"references-count":11,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2024,11,14]]}},"URL":"https:\/\/doi.org\/10.52321\/igh.38.1.81","relation":{},"ISSN":["0204-7934","2738-6996"],"issn-type":[{"type":"print","value":"0204-7934"},{"type":"electronic","value":"2738-6996"}],"subject":[],"published":{"date-parts":[[2024,11,12]]}}}