Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO)
<p>Detailed ocean currents in the southeastern tropical Indian Ocean adjacent to southern Sumatran and Javan coasts have not been fully explained because of limited observations. In this study, zonal current characteristics in the region have been studied using simulation results of a <span...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2021-08-01
|
| Series: | Ocean Science |
| Online Access: | https://os.copernicus.org/articles/17/1115/2021/os-17-1115-2021.pdf |
| _version_ | 1819239344546775040 |
|---|---|
| author | N. S. Ningsih S. L. Sakina R. D. Susanto R. D. Susanto F. Hanifah |
| author_facet | N. S. Ningsih S. L. Sakina R. D. Susanto R. D. Susanto F. Hanifah |
| author_sort | N. S. Ningsih |
| collection | DOAJ |
| description | <p>Detailed ocean currents in the southeastern tropical
Indian Ocean adjacent to southern Sumatran and Javan coasts have not been fully
explained because of limited observations. In this study, zonal current
characteristics in the region have been studied using simulation results of
a <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1</mn><mo>/</mo><mn mathvariant="normal">8</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="662cb2a7794bd25e9cc281e4f1640295"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-17-1115-2021-ie00001.svg" width="20pt" height="14pt" src="os-17-1115-2021-ie00001.png"/></svg:svg></span></span><span class="inline-formula"><sup>∘</sup></span> global hybrid coordinate ocean model from 1950 to 2013. The
simulated zonal currents across three meridional sections were then
investigated using an empirical orthogonal function (EOF), where the first
three modes account for 75 %–98 % of the total variance. The first temporal
mode of EOF is then investigated using ensemble empirical mode decomposition
(EEMD) to distinguish the signals.</p>
<p>This study has revealed distinctive features of currents in the South Java
Current (SJC) region, the Indonesian Throughflow (ITF)–South Equatorial
Current (SEC) region, and the transition zone between these regions. The
vertical structures of zonal currents in southern Java and offshore Sumatra are
characterized by a one-layer flow. Conversely, a two-layer flow is observed
in the nearshore and transition regions of Sumatra. Current variation in the
SJC region has peak energies that are sequentially dominated by
semiannual, intraseasonal, and annual timescales. Meanwhile, the transition
zone is characterized by semiannual and intraseasonal periods with
pronounced interannual variations. In contrast, interannual variability
associated with El
Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) modulates the prominent intraseasonal
variability of current in the ITF–SEC region. ENSO has the strongest
influence at the outflow ITF, while the IOD's strongest influence is in southwestern
Sumatra, with the ENSO (IOD) leading the current by 4 months (1 month).
Moreover, the contributions (largest to smallest) of each EEMD mode at the
nearshore of Java and offshore Sumatra are intraseasonal, semiannual,
annual, interannual, and long-term fluctuations. The contribution of
long-term variation (19.2 %) in the far offshore eastern Indian Ocean is
larger than the interannual (16.3 %) and annual (14.7 %) variations.
Future studies should be conducted to investigate this long-term variation.</p> |
| first_indexed | 2024-12-23T13:50:38Z |
| format | Article |
| id | doaj.art-0f6f03c761514662b08d28d3fc2f8981 |
| institution | Directory Open Access Journal |
| issn | 1812-0784 1812-0792 |
| language | English |
| last_indexed | 2024-12-23T13:50:38Z |
| publishDate | 2021-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Ocean Science |
| spelling | doaj.art-0f6f03c761514662b08d28d3fc2f89812022-12-21T17:44:36ZengCopernicus PublicationsOcean Science1812-07841812-07922021-08-01171115114010.5194/os-17-1115-2021Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO)N. S. Ningsih0S. L. Sakina1R. D. Susanto2R. D. Susanto3F. Hanifah4Research Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung, IndonesiaDepartment of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung, IndonesiaDepartment of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung, IndonesiaDepartment of Atmospheric & Oceanic Science, University of Maryland, College Park, USAResearch Group of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Bandung, Indonesia<p>Detailed ocean currents in the southeastern tropical Indian Ocean adjacent to southern Sumatran and Javan coasts have not been fully explained because of limited observations. In this study, zonal current characteristics in the region have been studied using simulation results of a <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">1</mn><mo>/</mo><mn mathvariant="normal">8</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="662cb2a7794bd25e9cc281e4f1640295"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="os-17-1115-2021-ie00001.svg" width="20pt" height="14pt" src="os-17-1115-2021-ie00001.png"/></svg:svg></span></span><span class="inline-formula"><sup>∘</sup></span> global hybrid coordinate ocean model from 1950 to 2013. The simulated zonal currents across three meridional sections were then investigated using an empirical orthogonal function (EOF), where the first three modes account for 75 %–98 % of the total variance. The first temporal mode of EOF is then investigated using ensemble empirical mode decomposition (EEMD) to distinguish the signals.</p> <p>This study has revealed distinctive features of currents in the South Java Current (SJC) region, the Indonesian Throughflow (ITF)–South Equatorial Current (SEC) region, and the transition zone between these regions. The vertical structures of zonal currents in southern Java and offshore Sumatra are characterized by a one-layer flow. Conversely, a two-layer flow is observed in the nearshore and transition regions of Sumatra. Current variation in the SJC region has peak energies that are sequentially dominated by semiannual, intraseasonal, and annual timescales. Meanwhile, the transition zone is characterized by semiannual and intraseasonal periods with pronounced interannual variations. In contrast, interannual variability associated with El Niño–Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) modulates the prominent intraseasonal variability of current in the ITF–SEC region. ENSO has the strongest influence at the outflow ITF, while the IOD's strongest influence is in southwestern Sumatra, with the ENSO (IOD) leading the current by 4 months (1 month). Moreover, the contributions (largest to smallest) of each EEMD mode at the nearshore of Java and offshore Sumatra are intraseasonal, semiannual, annual, interannual, and long-term fluctuations. The contribution of long-term variation (19.2 %) in the far offshore eastern Indian Ocean is larger than the interannual (16.3 %) and annual (14.7 %) variations. Future studies should be conducted to investigate this long-term variation.</p>https://os.copernicus.org/articles/17/1115/2021/os-17-1115-2021.pdf |
| spellingShingle | N. S. Ningsih S. L. Sakina R. D. Susanto R. D. Susanto F. Hanifah Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) Ocean Science |
| title | Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) |
| title_full | Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) |
| title_fullStr | Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) |
| title_full_unstemmed | Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) |
| title_short | Simulated zonal current characteristics in the southeastern tropical Indian Ocean (SETIO) |
| title_sort | simulated zonal current characteristics in the southeastern tropical indian ocean setio |
| url | https://os.copernicus.org/articles/17/1115/2021/os-17-1115-2021.pdf |
| work_keys_str_mv | AT nsningsih simulatedzonalcurrentcharacteristicsinthesoutheasterntropicalindianoceansetio AT slsakina simulatedzonalcurrentcharacteristicsinthesoutheasterntropicalindianoceansetio AT rdsusanto simulatedzonalcurrentcharacteristicsinthesoutheasterntropicalindianoceansetio AT rdsusanto simulatedzonalcurrentcharacteristicsinthesoutheasterntropicalindianoceansetio AT fhanifah simulatedzonalcurrentcharacteristicsinthesoutheasterntropicalindianoceansetio |