A Simple Model of Sea-Surface Cooling under a Tropical Cyclone

A major ocean response to tropical cyclone (TC) wind is the mixing of warm sea-surface water with cool subsurface water, which decreases the sea-surface temperature (SST). The decreased SST (δT) under the TC (rather than the cooled water in the wake after the storm has passed) modifies the storm’s i...

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Main Author: Leo Oey
Format: Article
Language:English
Published: MDPI AG 2023-02-01
Series:Journal of Marine Science and Engineering
Subjects:
Online Access:https://www.mdpi.com/2077-1312/11/2/397
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author Leo Oey
author_facet Leo Oey
author_sort Leo Oey
collection DOAJ
description A major ocean response to tropical cyclone (TC) wind is the mixing of warm sea-surface water with cool subsurface water, which decreases the sea-surface temperature (SST). The decreased SST (δT) under the TC (rather than the cooled water in the wake after the storm has passed) modifies the storm’s intensity and is of interest to TC intensity studies. Here, the author shows that δT (non-dimensionalized by some reference temperature) is linearly related to Ψ, a dimensionless (nonlinear) function of TC and ocean parameters: the TC maximum wind, radius, and translation speed, as well as the ocean’s 26 °C and 20 °C isothermal depths (Z<sub>26</sub> and Z<sub>20</sub>). The Ψ can be estimated from observations. The modelled δT is validated against sea-surface cooling observed by satellites, δT<sub>o</sub>, for typhoons during the May–December 2015 period in the western North Pacific. The result yields a best-fit, linear relation between δT<sub>o</sub> and Ψ that explains ~60% of the observed variance: r<sup>2</sup> ≈ 0.6 (99% confidence). Tests show that the cube of the TC maximum wind and the ocean’s Z<sub>26</sub> account for 46% and 7%, respectively, of the observed variance, indicating their predominant influence on TC-induced cooling. Contributions from other parameters are less but not negligible.
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spelling doaj.art-09b6ede86b534851933274a1ee313b572023-11-16T21:28:34ZengMDPI AGJournal of Marine Science and Engineering2077-13122023-02-0111239710.3390/jmse11020397A Simple Model of Sea-Surface Cooling under a Tropical CycloneLeo Oey0Forrestal Campus, Princeton University, Princeton, NJ 08544, USAA major ocean response to tropical cyclone (TC) wind is the mixing of warm sea-surface water with cool subsurface water, which decreases the sea-surface temperature (SST). The decreased SST (δT) under the TC (rather than the cooled water in the wake after the storm has passed) modifies the storm’s intensity and is of interest to TC intensity studies. Here, the author shows that δT (non-dimensionalized by some reference temperature) is linearly related to Ψ, a dimensionless (nonlinear) function of TC and ocean parameters: the TC maximum wind, radius, and translation speed, as well as the ocean’s 26 °C and 20 °C isothermal depths (Z<sub>26</sub> and Z<sub>20</sub>). The Ψ can be estimated from observations. The modelled δT is validated against sea-surface cooling observed by satellites, δT<sub>o</sub>, for typhoons during the May–December 2015 period in the western North Pacific. The result yields a best-fit, linear relation between δT<sub>o</sub> and Ψ that explains ~60% of the observed variance: r<sup>2</sup> ≈ 0.6 (99% confidence). Tests show that the cube of the TC maximum wind and the ocean’s Z<sub>26</sub> account for 46% and 7%, respectively, of the observed variance, indicating their predominant influence on TC-induced cooling. Contributions from other parameters are less but not negligible.https://www.mdpi.com/2077-1312/11/2/397tropical cycloneswind powerupper-ocean warm layer Z<sub>26</sub>sea-surface coolingocean mixingSST
spellingShingle Leo Oey
A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
Journal of Marine Science and Engineering
tropical cyclones
wind power
upper-ocean warm layer Z<sub>26</sub>
sea-surface cooling
ocean mixing
SST
title A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
title_full A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
title_fullStr A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
title_full_unstemmed A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
title_short A Simple Model of Sea-Surface Cooling under a Tropical Cyclone
title_sort simple model of sea surface cooling under a tropical cyclone
topic tropical cyclones
wind power
upper-ocean warm layer Z<sub>26</sub>
sea-surface cooling
ocean mixing
SST
url https://www.mdpi.com/2077-1312/11/2/397
work_keys_str_mv AT leooey asimplemodelofseasurfacecoolingunderatropicalcyclone
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