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  <front>
    <journal-meta>
      <journal-id journal-id-type="publisher-id">Ecological Safety of Coastal and Shelf Zones of Sea</journal-id>
      <journal-title-group>
        <journal-title>Ecological Safety of Coastal and Shelf Zones of Sea</journal-title>
      </journal-title-group>
      <issn publication-format="print">2413-5577</issn>
    </journal-meta>
    <article-meta>
      <article-id pub-id-type="publisher-id">20240102</article-id>
      
      <article-categories>
        <subj-group subj-group-type="article-type">
          <subject>Research Article</subject>
        </subj-group>
      </article-categories>

      <title-group>
        <article-title>Distribution of Sea Surface Elevations in the Form of a Two-Component Gaussian Mixture</article-title>
      </title-group>

      <contrib-group>
        <contrib contrib-type="author">
          <name>
            <surname>Zapevalov</surname>
            <given-names>A. S.</given-names>
          </name>
          <address>
            <country country="RU">Russian Federation</country>
          </address>
          <email>sevzepter@mail.ru</email>
          <xref ref-type="aff" rid="aff1"/>
        </contrib>
        <contrib contrib-type="author">
          <name>
            <surname>Knyazkov</surname>
            <given-names>A. S.</given-names>
          </name>
          <address>
            <country country="RU">Russian Federation</country>
          </address>
          <email>fizfak83@yandex.ru</email>
          <xref ref-type="aff" rid="aff1"/>
        </contrib>
      </contrib-group>

      <aff id="aff1">
        <institution>Marine Hydrophysical Institute of RAS</institution>
        <addr-line>Sevastopol</addr-line>
        <country country="RU">Russian Federation</country>
      </aff>

      <pub-date date-type="pub" iso-8601-date="2024-03-25" publication-format="electronic">
        <day>25</day>
        <month>03</month>
        <year>2024</year>
      </pub-date>
      <volume>2024</volume>
      <issue>1</issue>
      <fpage>20</fpage>
      <lpage>30</lpage>

      <history>
        <date date-type="received" iso-8601-date="2023-07-06">
          <day>06</day>
          <month>07</month>
          <year>2023</year>
        </date>
        <date date-type="rev-recd" iso-8601-date="2023-12-27">
          <day>27</day>
          <month>12</month>
          <year>2023</year>
        </date>
        <date date-type="accepted" iso-8601-date="2023-09-03">
          <day>03</day>
          <month>09</month>
          <year>2023</year>
        </date>
      </history>

      <permissions>
        <copyright-statement>Copyright © 2024, A. S. Zapevalov, A. S. Knyazkov</copyright-statement>
        <copyright-year>2024</copyright-year>
        <copyright-holder>A. S. Zapevalov, A. S. Knyazkov</copyright-holder>
        <ali:free_to_read xmlns:ali="http://www.niso.org/schemas/ali/1.0/"/>
        <license>
          <ali:license_ref xmlns:ali="http://www.niso.org/schemas/ali/1.0/">https://creativecommons.org/licenses/by-nc/4.0/</ali:license_ref>
        </license>
      </permissions>

      <self-uri xlink:href="https://ecological-safety.ru/en/repository/issues/2024/01/02/" xlink:title="Page of article">https://ecological-safety.ru/en/repository/issues/2024/01/02/</self-uri>

      <abstract>
        <p>The approximation of the probability density function of sea surface elevations by a two-component Gaussian mixture has been verified. For verification, the data of direct wave measurements obtained on a stationary oceanographic platform, installed in the Black Sea, were used. The approximation correctness criterion is the relative error ε of deviation of the model of probability densities function from the experimental function calculated from the measurement data. The average error ⟨ε⟩ over the ensemble of situations is small if |ξ| &lt; 3. The standard deviation δ is minimal if |ξ| ≈ 0 and is equal to 0.12, if |ξ| = 3 then δ ≈ 0.5. It is shown that the error ⟨ε⟩ has a systematic component, which depends on the deviations of the third and fourth statistical moments from the values corresponding to the Gaussian distribution. A semi-empirical relationship has been constructed to take this component into account. It is noted that the approximation accuracy can be increased by 2-3 times by eliminating the systematic component.</p>
      </abstract>

      <kwd-group>
        <kwd>Gaussian mixture</kwd>
        <kwd>sea waves</kwd>
        <kwd>surface elevation</kwd>
        <kwd>nonlinear waves</kwd>
        <kwd>statistical moment</kwd>
        <kwd>Black Sea</kwd>
      </kwd-group>

      <funding-group>
        <funding-statement>The work was performed under state assignment of Marine Hydrophysical Institute of RAS on topic FNNN-2021-0004 "Fundamental studies of oceanological processes which determine the state and evolution of the marine environment influenced by natural and anthropogenic factors, based on observation and modeling methods".</funding-statement>
      </funding-group>

      <author-notes>
        <p><bold>About the authors:</bold></p>
        <p><bold>Aleksandr S. Zapevalov</bold>, Chief Research Associate, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russian Federation), Dr.Sci. (Phys.-Math.), <bold>Scopus Author ID: 7004433476</bold>, <bold>ResearcherID: V-7880-2017</bold>, <bold>ORCID: 0000-0001-9942-2796</bold>, <email>sevzepter@mail.ru</email></p>
        <p><bold>Aleksandr S. Knyazkov</bold>, Leading Engineer, Marine Hydrophysical Institute of RAS (2 Kapitanskaya St., Sevastopol, 299011, Russian Federation), <bold>ORCID: 0000-0003-1119-1757</bold>, <email>fizfak83@yandex.ru</email></p>
        <p><bold>Contribution of the authors:</bold></p>
        <p><bold>Aleksandr S. Zapevalov</bold> – task statement, review of literature on the study topic, article preparation</p>
        <p><bold>Aleksandr S. Knyazkov</bold> – algorithm development and calculation performance, critical analysis of the calculations</p>
        <p><italic>The authors have read and approved the final manuscript.</italic></p>
      </author-notes>
    </article-meta>
  </front>

  <body>
    <p>Article text not included.</p>
  </body>

  <back>
    <ref-list>
      <title>REFERENCES</title>
      <ref id="B1">
        <label>1.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Longuet-Higgins</surname><given-names>M.S.</given-names></name>
          </person-group>
          <article-title>The Effect of Non-Linearities on Statistical Distributions in the Theory of Sea Waves</article-title>
          <source>Journal of Fluid Mechanics</source>
          <year>1963</year>
          <volume>17</volume>
          <issue>3</issue>
          <fpage>459</fpage>
          <lpage>480</lpage>
          <pub-id pub-id-type="doi">10.1017/S0022112063001452</pub-id>
        </element-citation>
      </ref>
      <ref id="B2">
        <label>2.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Hayne</surname><given-names>G.S.</given-names></name>
          </person-group>
          <article-title>Radar Altimeter Mean Return Waveforms from Near-Normal-Incidence Ocean Surface Scattering</article-title>
          <source>IEEE Transactions on Antennas and Propagation</source>
          <year>1980</year>
          <volume>28</volume>
          <issue>5</issue>
          <fpage>687</fpage>
          <lpage>692</lpage>
          <pub-id pub-id-type="doi">10.1109/TAP.1980.1142398</pub-id>
        </element-citation>
      </ref>
      <ref id="B3">
        <label>3.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Kay</surname><given-names>S.</given-names></name>
            <name><surname>Hedley</surname><given-names>J.D.</given-names></name>
            <name><surname>Lavender</surname><given-names>S.</given-names></name>
          </person-group>
          <article-title>Sun Glint Correction of High and Low Spatial Resolution Images of Aquatic Scenes: A Review of Methods for Visible and Near-Infrared Wavelengths</article-title>
          <source>Remote Sensing</source>
          <year>2009</year>
          <volume>1</volume>
          <issue>4</issue>
          <fpage>697</fpage>
          <lpage>730</lpage>
          <pub-id pub-id-type="doi">10.3390/rs1040697</pub-id>
        </element-citation>
      </ref>
      <ref id="B4">
        <label>4.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Annenkov</surname><given-names>S.Y.</given-names></name>
            <name><surname>Shrira</surname><given-names>V.I.</given-names></name>
          </person-group>
          <article-title>Evaluation of Skewness and Kurtosis of Wind Waves Parameterized by JONSWAP Spectra</article-title>
          <source>Journal of Physical Oceanography</source>
          <year>2014</year>
          <volume>44</volume>
          <issue>6</issue>
          <fpage>1582</fpage>
          <lpage>1594</lpage>
          <pub-id pub-id-type="doi">10.1175/JPO-D-13-0218.1</pub-id>
        </element-citation>
      </ref>
      <ref id="B5">
        <label>5.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Breon</surname><given-names>F.M.</given-names></name>
            <name><surname>Henriot</surname><given-names>N.</given-names></name>
          </person-group>
          <article-title>Spaceborne Observations of Ocean Glint Reflectance and Modeling of Wave Slope Distributions</article-title>
          <source>Journal of Geophysical Research: Oceans</source>
          <year>2006</year>
          <volume>111</volume>
          <issue>C6</issue>
          <fpage>C06005</fpage>
          <pub-id pub-id-type="doi">10.1029/2005JC003343</pub-id>
        </element-citation>
      </ref>
      <ref id="B6">
        <label>6.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Callahan</surname><given-names>P.S.</given-names></name>
            <name><surname>Rodriguez</surname><given-names>E.</given-names></name>
          </person-group>
          <article-title>Retracking of Jason-1 Data</article-title>
          <source>Marine Geodesy</source>
          <year>2004</year>
          <volume>27</volume>
          <issue>3-4</issue>
          <fpage>391</fpage>
          <lpage>407</lpage>
          <pub-id pub-id-type="doi">10.1080/01490410490902098</pub-id>
        </element-citation>
      </ref>
      <ref id="B7">
        <label>7.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Kwon</surname><given-names>O.K.</given-names></name>
          </person-group>
          <article-title>Analytic Expressions for the Positive Definite and Unimodal Regions of Gram-Charlier Series</article-title>
          <source>Communications in Statistics - Theory and Methods</source>
          <year>2022</year>
          <volume>51</volume>
          <issue>15</issue>
          <fpage>5064</fpage>
          <lpage>5084</lpage>
          <pub-id pub-id-type="doi">10.1080/03610926.2020.1833219</pub-id>
        </element-citation>
      </ref>
      <ref id="B8">
        <label>8.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Lin</surname><given-names>W.</given-names></name>
            <name><surname>Zhang</surname><given-names>J.E.</given-names></name>
          </person-group>
          <article-title>The Valid Regions of Gram-Charlier Densities with High-Order Cumulants</article-title>
          <source>Journal of Computational and Applied Mathematics</source>
          <year>2022</year>
          <volume>407</volume>
          <fpage>113945</fpage>
          <pub-id pub-id-type="doi">10.1016/j.cam.2021.113945</pub-id>
        </element-citation>
      </ref>
      <ref id="B9">
        <label>9.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Blinnikov</surname><given-names>S.</given-names></name>
            <name><surname>Moessner</surname><given-names>R.</given-names></name>
          </person-group>
          <article-title>Expansions for Nearly Gaussian Distributions</article-title>
          <source>Astronomy and Astrophysics Supplement Series</source>
          <year>1998</year>
          <volume>130</volume>
          <issue>1</issue>
          <fpage>193</fpage>
          <lpage>205</lpage>
          <pub-id pub-id-type="doi">10.1051/aas:1998221</pub-id>
        </element-citation>
      </ref>
      <ref id="B10">
        <label>10.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Zapevalov</surname><given-names>A.S.</given-names></name>
            <name><surname>Knyazkov</surname><given-names>A.S.</given-names></name>
          </person-group>
          <article-title>Statistical Description of the Sea Surface by Two-Component Gaussian Mixture</article-title>
          <source>Physical Oceanography</source>
          <year>2022</year>
          <volume>29</volume>
          <issue>4</issue>
          <fpage>395</fpage>
          <lpage>403</lpage>
        </element-citation>
      </ref>
      <ref id="B11">
        <label>11.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Zapevalov</surname><given-names>A.S.</given-names></name>
            <name><surname>Ratner</surname><given-names>Y.B.</given-names></name>
          </person-group>
          <article-title>Analytic Model of the Probability Density of Slopes of the Sea Surface</article-title>
          <source>Physical Oceanography</source>
          <year>2003</year>
          <volume>13</volume>
          <issue>1</issue>
          <fpage>1</fpage>
          <lpage>13</lpage>
          <pub-id pub-id-type="doi">10.1023/A:1022444703787</pub-id>
        </element-citation>
      </ref>
      <ref id="B12">
        <label>12.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Tatarskii</surname><given-names>V.I.</given-names></name>
          </person-group>
          <article-title>Multi-Gaussian Representation of the Cox-Munk Distribution for Slopes of Wind-Driven Waves</article-title>
          <source>Journal of Atmospheric and Oceanic Technology</source>
          <year>2003</year>
          <volume>20</volume>
          <issue>11</issue>
          <fpage>1697</fpage>
          <lpage>1705</lpage>
          <pub-id pub-id-type="doi">10.1175/1520-0426(2003)020&lt;1697:MROTCD&gt;2.0.CO;2</pub-id>
        </element-citation>
      </ref>
      <ref id="B13">
        <label>13.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Gao</surname><given-names>Z.</given-names></name>
            <name><surname>Sun</surname><given-names>Z.</given-names></name>
            <name><surname>Liang</surname><given-names>S.</given-names></name>
          </person-group>
          <article-title>Probability Density Function for Wave Elevation Based on Gaussian Mixture Models</article-title>
          <source>Ocean Engineering</source>
          <year>2020</year>
          <volume>213</volume>
          <fpage>107815</fpage>
          <pub-id pub-id-type="doi">10.1016/j.oceaneng.2020.107815</pub-id>
        </element-citation>
      </ref>
      <ref id="B14">
        <label>14.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Carreira-Perpinan</surname><given-names>M.A.</given-names></name>
          </person-group>
          <article-title>Mode-Finding for Mixtures of Gaussian Distributions</article-title>
          <source>IEEE Transactions on Pattern Analysis and Machine Intelligence</source>
          <year>2000</year>
          <volume>22</volume>
          <issue>11</issue>
          <fpage>1318</fpage>
          <lpage>1323</lpage>
          <pub-id pub-id-type="doi">10.1109/34.888716</pub-id>
        </element-citation>
      </ref>
      <ref id="B15">
        <label>15.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Aprausheva</surname><given-names>N.N.</given-names></name>
            <name><surname>Sorokin</surname><given-names>S.V.</given-names></name>
          </person-group>
          <article-title>Exact Equation of the Boundary of Unimodal and Bimodal Domains of a Two-Component Gaussian Mixture</article-title>
          <source>Pattern Recognition and Image Analysis</source>
          <year>2013</year>
          <volume>23</volume>
          <issue>3</issue>
          <fpage>341</fpage>
          <lpage>347</lpage>
          <pub-id pub-id-type="doi">10.1134/S1054661813030024</pub-id>
        </element-citation>
      </ref>
      <ref id="B16">
        <label>16.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Babanin</surname><given-names>A.V.</given-names></name>
            <name><surname>Polnikov</surname><given-names>V.G.</given-names></name>
          </person-group>
          <article-title>On the Non-Gaussian Nature of Wind Waves</article-title>
          <source>Physical Oceanography</source>
          <year>1995</year>
          <volume>6</volume>
          <issue>3</issue>
          <fpage>241</fpage>
          <lpage>245</lpage>
          <pub-id pub-id-type="doi">10.1007/BF02197522</pub-id>
        </element-citation>
      </ref>
      <ref id="B17">
        <label>17.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Guedes Soares</surname><given-names>C.</given-names></name>
            <name><surname>Cherneva</surname><given-names>Z.</given-names></name>
            <name><surname>Antão</surname><given-names>E.M.</given-names></name>
          </person-group>
          <article-title>Characteristics of Abnormal Waves in North Sea Storm Sea States</article-title>
          <source>Applied Ocean Research</source>
          <year>2003</year>
          <volume>25</volume>
          <issue>6</issue>
          <fpage>337</fpage>
          <lpage>344</lpage>
          <pub-id pub-id-type="doi">10.1016/j.apor.2004.02.005</pub-id>
        </element-citation>
      </ref>
      <ref id="B18">
        <label>18.</label>
        <element-citation publication-type="paper-conference">
          <person-group person-group-type="author">
            <name><surname>Jha</surname><given-names>A.K.</given-names></name>
            <name><surname>Winterstein</surname><given-names>S.R.</given-names></name>
          </person-group>
          <article-title>Nonlinear Random Ocean Waves: Prediction and Comparison with Data</article-title>
          <source>Proceedings of the 19th International Offshore Mechanics and Arctic Engineering Symposium</source>
          <publisher-loc>New Orleans, USA</publisher-loc>
          <year>2000</year>
          <fpage>Paper No. 00-6125</fpage>
        </element-citation>
      </ref>
      <ref id="B19">
        <label>19.</label>
        <element-citation publication-type="journal">
          <person-group person-group-type="author">
            <name><surname>Zapevalov</surname><given-names>A.S.</given-names></name>
            <name><surname>Garmashov</surname><given-names>A.V.</given-names></name>
          </person-group>
          <article-title>Skewness and Kurtosis of the Surface Wave in the Coastal Zone of the Black Sea</article-title>
          <source>Physical Oceanography</source>
          <year>2021</year>
          <volume>28</volume>
          <issue>4</issue>
          <fpage>414</fpage>
          <lpage>425</lpage>
          <pub-id pub-id-type="doi">10.22449/1573-160X-2021-4-414-425</pub-id>
        </element-citation>
      </ref>
      <ref id="B20">
        <label>20.</label>
        <element-citation publication-type="paper-conference">
          <person-group person-group-type="author">
            <name><surname>Toloknov</surname><given-names>Yu.N.</given-names></name>
            <name><surname>Korovushkin</surname><given-names>A.I.</given-names></name>
          </person-group>
          <article-title>The System of Collecting Hydrometeorological Information</article-title>
          <source>Monitoring Systems of Environment</source>
          <publisher-loc>Sevastopol</publisher-loc>
          <publisher-name>ECOSI-Gidrofizika</publisher-name>
          <year>2010</year>
          <issue>13</issue>
          <fpage>50</fpage>
          <lpage>53</lpage>
          <comment>(in Russian)</comment>
        </element-citation>
      </ref>
    </ref-list>
  </back>
</article>
