Scaling and intermittent properties of oceanic and atmospheric <i>p</i>CO<sub>2</sub> time series and their difference in a turbulence framework
<p>In this study, the multiscale dynamics of 38 oceanic and atmospheric <span class="inline-formula"><i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> time series from fixed Eulerian buoys recorded with 3 h res...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-01-01
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| Series: | Nonlinear Processes in Geophysics |
| Online Access: | https://npg.copernicus.org/articles/32/35/2025/npg-32-35-2025.pdf |
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| Summary: | <p>In this study, the multiscale dynamics of 38 oceanic and atmospheric <span class="inline-formula"><i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> time series from fixed Eulerian buoys recorded with 3 h resolution are considered, and their multifractal properties are demonstrated. The difference between these time series, the sea surface temperature data and the sea surface salinity data were also studied. These series possess multiscale turbulent-like fluctuations and display scaling properties from 3 h to the annual scale. Scaling exponents are estimated through Fourier analysis, and their average quantities were considered globally for all parameters, as well as for different ecosystems such as coastal shelf, coral reefs and open ocean. Sea surface temperature is the only parameter for which a spectral slope close to <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">5</mn><mo>/</mo><mn mathvariant="normal">3</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="ba5d408bbcf130091b00ac176fd54124"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="npg-32-35-2025-ie00001.svg" width="20pt" height="14pt" src="npg-32-35-2025-ie00001.png"/></svg:svg></span></span> is found, corresponding to a passive scalar in homogeneous and isotropic turbulence. The other parameters had smaller spectral slopes, from <span class="inline-formula">1.22</span> to <span class="inline-formula">1.45</span>. By using empirical mode decomposition of the time series, together with generalized Hilbert spectral analysis, the intermittency of the time series was considered in the multifractal framework. Concave moment functions were estimated, and Hurst indices <span class="inline-formula"><i>H</i></span> and intermittency parameters <span class="inline-formula"><i>μ</i></span> were determined in the framework of a lognormal multifractal fit. We obtained mean values of <span class="inline-formula"><i>H</i>=0.26</span> and <span class="inline-formula">0.21</span>, respectively, for oceanic and atmospheric <span class="inline-formula"><i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> time series and <span class="inline-formula"><i>μ</i>=0.08</span> for both. It is the first time that atmospheric and oceanic <span class="inline-formula"><i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> and their difference <span class="inline-formula">Δ<i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> are studied using such an intermittent turbulence framework. The <span class="inline-formula">Δ<i>p</i></span><span class="inline-formula">CO<sub>2</sub></span> time series was shown to possess a power-law scaling with an exponent of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="italic">β</mi><mo>=</mo><mn mathvariant="normal">1.36</mn><mo>±</mo><mn mathvariant="normal">0.19</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="76pt" height="12pt" class="svg-formula" dspmath="mathimg" md5hash="c664dd55d59146fe99ced31a68c69282"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="npg-32-35-2025-ie00002.svg" width="76pt" height="12pt" src="npg-32-35-2025-ie00002.png"/></svg:svg></span></span>.</p> |
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| ISSN: | 1023-5809 1607-7946 |