Upper-ocean response to the passage of tropical cyclones in the Azores region
<p>Tropical cyclones (TCs) are extreme climate events that are known to strongly interact with the ocean through two mechanisms: dynamically through the associated intense wind stress and thermodynamically through moist enthalpy exchanges at the ocean surface. These interactions contribute to...
Main Authors: | , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2022-09-01
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Series: | Ocean Science |
Online Access: | https://os.copernicus.org/articles/18/1419/2022/os-18-1419-2022.pdf |
Summary: | <p>Tropical cyclones (TCs) are extreme climate events that are known
to strongly interact with the ocean through two mechanisms: dynamically
through the associated intense wind stress and thermodynamically through
moist enthalpy exchanges at the ocean surface. These interactions contribute
to relevant oceanic responses during and after the passage of a TC, namely
the induction of a cold wake and the production of chlorophyll (Chl <span class="inline-formula"><i>a</i></span>)
blooms. This study aimed to understand these interactions in the Azores
region, an area with relatively low cyclonic activity for the North Atlantic
basin, since the area experiences much less intense events than the rest of
the basin. Results for the 1998–2020 period showed that the averaged induced
anomalies were on the order of <span class="inline-formula">+0.050</span> mg m<span class="inline-formula"><sup>−3</sup></span> for Chl <span class="inline-formula"><i>a</i></span> and <span class="inline-formula">−1.615</span> <span class="inline-formula"><sup>∘</sup></span>C for SST (sea surface temperature). Furthermore, looking at the role played by
several TCs characteristics we found that the intensity of the TCs was the
most important condition for the development of upper-ocean responses.
Additionally, it was found that bigger TCs caused greater induced anomalies
in both variables, while faster ones created greater Chl <span class="inline-formula"><i>a</i></span> responses, and
TCs that occurred later in the season had greater TC-related anomalies. Two
case studies (Ophelia in 2017 and Nadine in 2012) were conducted to
better understand each upper-ocean response. Ophelia was shown to affect the
SST at an earlier stage, while the biggest Chl <span class="inline-formula"><i>a</i></span> induced anomalies were
registered at a later stage, allowing the conclusion that thermodynamic
exchanges conditioned the SST more while dynamical mixing might have played
a more important role in the later stage. Nadine showed the importance of
the TC track geometry, revealing that the TC track observed in each event
can impact a specific region for longer and therefore result in greater induced
anomalies.</p> |
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ISSN: | 1812-0784 1812-0792 |