The Levantine Intermediate Water in the western Mediterranean and its interactions with the Algerian Gyres: insights from 60 years of observation
<p>The presence of two large-scale cyclonic gyres in the Algerian Basin influences the general and eddy circulation, but their effects on water mass transfer remain poorly characterized. Our study has confirmed the presence of these gyres using the first direct current measurements of the whol...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-07-01
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| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/18/937/2022/os-18-937-2022.pdf |
| Summary: | <p>The presence of two large-scale cyclonic gyres in the Algerian Basin influences the general and eddy circulation, but their effects on water mass
transfer remain poorly characterized. Our study has confirmed the presence of these gyres using the first direct current measurements of the whole
water column collected during the SOMBA-GE2014 cruise, specifically designed to investigate these gyres. Using cruise sections and a climatology
from 60 years of in situ measurements, we have also shown the effect of these gyres on the distribution at intermediate depth of Levantine
Intermediate Water (LIW) with warmer (<span class="inline-formula">∼</span> 0.15 <span class="inline-formula"><sup>∘</sup>C</span>) and saltier (<span class="inline-formula">∼</span> 0.02) characteristics in the Algerian Basin than in the
Provençal Basin. The Algerian Gyres, combined with the effect of anticyclonic Algerian Eddies, also impact horizontal density gradients with sinking
of the isopycnals at the gyres' centers. Temporal cross-correlation of LIW potential temperature referenced to a signal observed southwest of
Sardinia reveals a timescale of transit of 4 months to get to the center of the Algerian Basin.</p>
<p>The LIW potential temperature and salinity trends, on average in the basin interior, are estimated to be
<span class="inline-formula">+</span>0.0022 <span class="inline-formula">±</span> 0.0002 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi/><mo>∘</mo></msup><mi mathvariant="normal">C</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="28c0b3f859693f23c216343abc480004"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-18-937-2022-ie00001.svg" width="34pt" height="15pt" src="os-18-937-2022-ie00001.png"/></svg:svg></span></span> and <span class="inline-formula">+</span>0.0022 <span class="inline-formula">±</span> 0.0001 <span class="inline-formula">yr<sup>−1</sup></span>, respectively, over the 1968–2017 period and
accelerating to <span class="inline-formula">+</span>0.048 <span class="inline-formula">±</span> 0.003 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi/><mo>∘</mo></msup><mi mathvariant="normal">C</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="ddbfc417e1eddef6096881fe045bbb7c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-18-937-2022-ie00002.svg" width="34pt" height="15pt" src="os-18-937-2022-ie00002.png"/></svg:svg></span></span> and <span class="inline-formula">+</span>0.0076 <span class="inline-formula">±</span> 0.0009 <span class="inline-formula">yr<sup>−1</sup></span> over the 2013–2017 period.</p> |
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| ISSN: | 1812-0784 1812-0792 |