1278:
39:
392:, thanks to the northeast seasonal wind from the continent. In the Indian Ocean, the NEC is faster than the SEC. Multiple reasons are considered. The equator-located NEC receives more solar heat than the more poleward-located SEC, which leads to a much denser but thinner upper layer for the NEC. The current flows faster in the thinner layer. Another reason is due to the smaller Coriolis effect at the equator. The NEC, thus, is more aligned to the westward wind on the equator.
252:
1289:
331:
153:
112:
a northward Ekman transport in the NEC and a southward Ekman transport in the SEC take place. Due to the fact that the Ekman transport is perpendicular to the flow itself, these Ekman transports contribute to the meridional branch of the NEC and SEC. However, the magnitude of the meridional component is of no comparison to the current itself.
54:), generated by the easterly trade wind in the southern hemisphere. Despite the well-coupled name of the two equatorial currents, the distribution of the NEC and the SEC is not in symmetry at the equator, but slightly northward to the equator. This asymmetric distribution is aligned to the location of the
407:. While during July and August, the location of the NEC moves southward and the Somali Current reverses. As a result, the NEC and the SEC feed Somali Current instead of the SECC. So, the SECC becomes very weak. Due to the prevailing southwest wind in the summer, the surface waters move from the southern
255:
a) shows the mean zonal surface currents within the
Atlantic in the first half-year (Jan-Jun) of 1997. b) shows the second half (Jul-Dec). These two figures show a strong seasonality, with NECC stronger during July to December. Positive values (red) represent eastward flow, negative values (blue) for
111:
is a wind-driven transport. It occurs due to the rotation of the globe. A transport is found to the right of the flow direction in the northern hemisphere, while to the left of the flow in the southern hemisphere. It is noteworthy that in the tropical regions, where NEC and SEC both flow to the west,
242:
This North
Equatorial Current Bifurcation (NECB) plays an important role in the south Asian climate system. As currently, climate change is more and more evident, thus, leading to a more amplified migration of the NECB. As a result, this amplification of the migration may lead to redistribution of
334:
This figure shows the mean zonal surface current of different periods in the Indian Ocean. a), b) and c) are currents during
January and February, during July and August, and in May, respectively. Positive values (red) represent eastward flow, negative values (blue) for westward flow.
156:
a) and b) show the mean zonal surface velocity in
Pacific during El Niño (1997) and La Niña years (1998). Positive values (red) represent eastward flow, negative values (blue) for westward flow. All the data plotted in this article is obtained from the GODAS dataset.
309:
and the NECC respectively. The northward meridional Ekman transport dominates the tropical
Atlantic Ocean, playing a very important role in the northward heat transport. This strong northward surface transport is well known as the upper component of the
302:, lower than in the Pacific. Instead of interannual variability, the NEC shows a strong seasonality, in which NECC is stronger from July to December, weaker from January to June. Besides, the NEC is more equatorward from January to June.
317:
On the interannual and longer timescales, the equatorial and tropical
Atlantic ocean has a strong interaction with the dynamics of several patterns of variabilities, the Atlantic Niño, the Atlantic Meridional Mode (AMM) and the
418:
During the transition of these two phases, specifically around May and
November, the NEC becomes very weak, almost invisible in Figure 3. Instead of the NEC, a strong eastward current is found near the equator, known as the
314:. On a seasonal time scale, variability of the heat transport is responsible for the tropical sea temperature anomaly. The temperature anomaly at the sea surface is a possible cause that leads to Atlantic hurricane season.
94:
can partly explain where the water ends up at. When the NEC and the SEC reached the west end of a basin, some of the water travels poleward to join the low-latitude circulations, while some travels equatorward to join the
226:
The meridional component of the NEC, also known as the Ekman transport, is evident northward at any location all the way along with itself. When the current reaches the west end, the
Philippines, it splits into two
395:
The NEC shows a very strong seasonal pattern. During
January and February, thanks to the prevailing northeast wind, the NEC travels all the way to the east coast of Somalia and joins the
90:
The NEC and SEC continuously flow westward. However, the seawater does not just pile up at the west basin surface. The advent water must have gone back to the east by some means. The
390:
300:
209:
132:
399:
flowing towards the southwest to feed the SECC. As a result, SECC is strong during the winter. And at this time, the NEC carries surface waters from the southern
339:
The NEC in the Indian ocean is strongly affected by the continent to the north. The NEC is more southward than the other two oceans, which drives the
513:
Wang, Xin (2020). "Variations of the North
Equatorial Current Bifurcation and the SSH in the Western Pacific Associated With El Niño Flavors".
420:
631:
Johnson, George C (2002). "Direct measurements of upper ocean currents and water properties across the tropical Pacific during the 1990s".
211:. The NEC shows little seasonal variability, but an interannual instability. The interannual instability of the NEC is strongly linked to
311:
139:
and the seasonal monsoon in the Indian ocean. Reversely, the climate motion also affects the behavior of the equatorial current itself.
445:"Structure and Variability of the North Equatorial Current/Undercurrent from Mooring Measurements at 130°E in the Western Pacific"
1313:
23:
is a westward wind-driven current mostly located near the equator, but the location varies from different oceans. The NEC in the
1318:
590:
260:
The NEC in the Atlantic is evident around 10°-20°N, spanning the longitude from 16°-60°W. The typical flow velocity is about
212:
128:
127:
The NEC, the SEC and the ECC play an important role in the climate system causing various of climate patterns, such as
350:
The NEC sits right on the equator, across a longitude from 45°-100°E. The typical speed in the winter can reach up to
319:
136:
46:
The NEC is driven by the north-hemisphere easterly trade wind. In couple with NEC, there is another current called
711:
119:, which occurs in between the NEC and the SEC, where a massive water divergence at the sea surface takes place.
55:
1111:
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1040:
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684:
344:
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84:
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243:
the water mass and heat transport along the western boundary, and thus warm pool and monsoon climate.
172:
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1090:
1075:
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913:
903:
51:
47:
35:
is very close to the equator. It ranges from the sea surface down to 400 m in the western Pacific.
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558:"Dynamics of the seasonal variation of the North Equatorial Current bifurcation"
1221:
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1005:
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843:
808:
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778:
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591:"Equatorial Atlantic variability—Modes, mechanisms, and global teleconnections"
396:
305:
The NEC splits into two after reaching the north of South America, joining the
28:
58:, which is the area that the northeast and the southeast trade wind converge.
1307:
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The NEC is evident around 10°-18°N across the entire Pacific basin, from
251:
1130:
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330:
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to the southern hemisphere. So, the counter current is called
152:
42:
North Equatorial Current (in black labeled N. Equatorial)
115:
Another subsequent result of the Ekman transport is the
356:
266:
175:
384:
312:Atlantic Meridional Overturning Circulation (AMOC)
294:
203:
231:. One of the branches flows poleward feeding the
66:
1305:
598:Wiley Interdisciplinary Reviews: Climate Change
705:
719:
582:
438:
436:
235:, another one flows equatorward feeding the
624:
122:
712:
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16:Current in the Pacific and Atlantic Oceans
573:
478:
468:
433:
588:
549:
506:
329:
250:
151:
37:
630:
515:Journal of Geophysical Research: Oceans
345:South Equatorial Counter Current (SECC)
325:
320:Atlantic Multidecadal Oscillation (AMO)
137:Atlantic Multidecadal Oscillation (AMO)
85:South Equatorial Counter Current (SECC)
81:North Equatorial Counter Current (NECC)
31:is about 5°-20°N, while the NEC in the
1306:
555:
142:
102:
693:
442:
83:in both Pacific and Atlantic and the
71:The NEC and the SEC will generate an
56:Intertropical Convergence Zone (ITCZ)
512:
61:
129:El Niño–Southern Oscillation (ENSO)
13:
14:
1330:
556:Chen, Zhaohui; Wu, Lixin (2020).
1287:
1276:
385:{\displaystyle 50cm\cdot s^{-1}}
295:{\displaystyle 10cm\cdot s^{-1}}
204:{\displaystyle 30cm\cdot s^{-1}}
169:. Its typical zonal velocity is
562:Journal of Geophysical Research
246:
1314:Currents of the Atlantic Ocean
495:
147:
67:The Equatorial Counter Current
21:North Equatorial Current (NEC)
1:
1319:Currents of the Pacific Ocean
653:10.1016/S0079-6611(02)00021-6
426:
7:
663:
10:
1335:
685:Equatorial Counter Current
589:Lübbecke, Joke F. (2018).
341:Equatorial Counter Current
307:North Brazil Current (NBC)
97:Equatorial Counter Current
73:Equatorial Counter Current
1272:
1204:
1174:
1138:
1129:
1104:
998:
922:
771:
740:
731:
215:. The NEC strengthens in
1264:Thermohaline circulation
633:Progress in Oceanography
133:Atlantic Meridional Mode
123:Interaction with climate
48:South Equatorial Current
1212:Atmospheric circulation
763:Transpolar Drift Stream
1283:Environment portal
1237:Marine garbage patches
1051:Indonesian Throughflow
955:Indonesian Throughflow
443:Zhang, Linlin (2017).
386:
336:
296:
257:
229:western boundary flows
205:
158:
43:
1112:Antarctic Circumpolar
680:Physical oceanography
387:
333:
297:
254:
219:years and weakens in
206:
155:
87:in the Indian Ocean.
41:
575:10.1029/2010JC006664
535:10.1029/2019JC015733
354:
326:The Indian Ocean NEC
264:
173:
1156:South Atlantic Gyre
1151:North Atlantic Gyre
645:2002PrOce..52...31J
610:2018WIRCC...9E.527L
527:2020JGRC..12515733W
461:2017NatSR...746310Z
143:In different oceans
103:The Ekman transport
1166:South Pacific Gyre
1161:North Pacific Gyre
1041:Equatorial Counter
945:Equatorial Counter
449:Scientific Reports
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1294:Oceans portal
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1146:Indian Ocean Gyre
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470:10.1038/srep46310
62:Related processes
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1217:Boundary current
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1091:South Equatorial
1076:North Korea Cold
1071:North Equatorial
985:South Equatorial
975:North Madagascar
914:West Spitsbergen
904:South Equatorial
884:North Equatorial
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403:to the southern
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237:Mindanao Current
233:Kuroshio Current
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92:Sverdrup balance
79:), named as the
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1036:East Korea Warm
1031:East Australian
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940:East Madagascar
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163:the Philippines
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109:Ekman transport
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935:Agulhas Return
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1247:Indian Ocean
1192:Weddell Gyre
1096:Tasman Front
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923:Indian Ocean
883:
879:North Brazil
829:East Iceland
741:Arctic Ocean
639:(1): 31–61.
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45:
33:Indian Ocean
20:
18:
1175:Other gyres
1139:Major gyres
849:Gulf Stream
421:Wyrtki jets
409:Arabian Sea
405:Arabian Sea
148:Pacific NEC
135:(AMM), the
1308:Categories
1016:California
970:Mozambique
965:Madagascar
427:References
1187:Ross Gyre
1056:Kamchatka
889:Norwegian
864:Lomonosov
819:Caribbean
814:Cape Horn
758:Norwegian
543:213035460
455:: 46310.
375:−
367:⋅
285:−
277:⋅
194:−
186:⋅
167:Nicaragua
117:upwelling
1066:Mindanao
1061:Kuroshio
1046:Humboldt
1026:Davidson
1021:Cromwell
1011:Aleutian
894:Portugal
859:Labrador
854:Irminger
834:Falkland
799:Benguela
784:Antilles
733:Currents
664:See also
489:28422095
29:Atlantic
27:and the
1205:Related
1086:Oyashio
960:Leeuwin
930:Agulhas
839:Florida
641:Bibcode
606:Bibcode
523:Bibcode
480:5395815
457:Bibcode
223:years.
221:El Niño
217:La Niña
25:Pacific
1006:Alaska
980:Somali
844:Guinea
809:Canary
804:Brazil
789:Azores
779:Angola
541:
487:
477:
347:here.
131:, the
1131:Gyres
725:gyres
604:(4).
594:(PDF)
539:S2CID
521:(1).
502:GODAS
869:Loop
723:and
485:PMID
213:ENSO
107:The
19:The
649:doi
614:doi
570:doi
566:145
531:doi
519:125
475:PMC
465:doi
165:to
77:ECC
52:SEC
1310::
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637:52
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483:.
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451:.
447:.
435:^
423:.
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