scholarly journals Differences in the Reaction of North Equatorial Countercurrent to the Developing and Mature Phase of ENSO Events in the Western Pacific Ocean

Climate ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 57
Author(s):  
Yusuf Jati Wijaya ◽  
Yukiharu Hisaki
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Enso Event ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
Mature Phase ◽  
La Nina ◽  
La Nina Event ◽  
The Western Pacific

The North Equatorial Countercurrent (NECC) is an eastward zonal current closely related to an El Niño Southern Oscillation (ENSO) event. This paper investigated the variations of NECC in the Western Pacific Ocean over 25 years (1993–2017) using satellite data provided by the Copernicus Marine Environment Monitoring Service (CMEMS) and the Remote Sensing System (RSS). The first mode of empirical orthogonal function (EOF) analysis showed that the NECC strengthened or weakened in each El Niño (La Niña) event during the developing or mature phase, respectively. We also found that the NECC shifting was strongly coincidental with an ENSO event. During the developing phase of an El Niño (La Niña) event, the NECC shifted southward (northward), and afterward, when it entered the mature phase, the NECC tended to shift slightly northward (southward). Moreover, the NECC strength was found to have undergone a weakening during the 2008–2017 period.

scholarly journals Biophysical responses near equatorial islands in the Western Pacific Ocean during El Niño/La Niña transitions

2013 ◽  
Vol 40 (20) ◽  
pp. 5473-5479 ◽  
Author(s):  
Michelle M. Gierach ◽  
Monique Messié ◽  
Tong Lee ◽  
Kristopher B. Karnauskas ◽  
Marie-Hélène Radenac
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
La Nina ◽  
The Western Pacific

scholarly journals Why Was the August Rainfall Pattern in the East Asia–Pacific Ocean Region in 2016 Different from That in 1998 under a Similar Preceding El Niño Background?

2019 ◽  
Vol 32 (18) ◽  
pp. 5785-5797 ◽  
Author(s):  
Dong Chen ◽  
Ya Gao ◽  
Huijun Wang
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern China ◽  
Western Pacific ◽  
Asia Pacific ◽  
Western Pacific Ocean ◽  
El Niño Event ◽  
Ocean Region ◽  
The Western Pacific

AbstractPrevious studies have noted that a strong El Niño event occurring in the preceding winter will result in westward stretching of the western North Pacific subtropical high (WPSH) in the following summer, causing anomalously high precipitation in the Yangtze–Huaihe River basin and anomalously low precipitation in southern China. The winters preceding the summers of 1998 and 2016 featured strong El Niño events, which, along with the El Niño event of 1982, represented the strongest El Niño events since 1950. Under these similar El Niño event backgrounds, the July precipitation anomaly in 2016 was similar to that in 1998, but the August precipitation anomalies in the two years featured opposite distributions. According to the atmospheric circulation analysis, we found that an anomalous ascending motion appeared over the Indian Ocean, while an anomalous descending motion appeared over the Pacific Ocean in August 1998. In addition, the WPSH stretched westward over southern China. However, the atmospheric circulation distribution in August 2016 was the opposite of that in 1998, and the WPSH was divided into eastern and western parts by the anomalous western Pacific cyclone. Further analysis showed that the number of tropical cyclones and typhoons over the western Pacific Ocean increased significantly in August 2016, and their activities were concentrated in the South China Sea (SCS)–southern China region and the western Pacific Ocean, resulting in the division of the WPSH. Therefore, the numbers, tracks, and strengths of tropical cyclones and typhoons were responsible for the differences in the anomalous precipitation distributions over the East Asia–Pacific Ocean region between August 2016 and August 1998.

scholarly journals Interactive Feedback between ENSO and the Indian Ocean

2006 ◽  
Vol 19 (9) ◽  
pp. 1784-1801 ◽  
Author(s):  
Jong-Seong Kug ◽  
In-Sik Kang
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
Western Pacific ◽  
Easterly Wind ◽  
Mature Phase ◽  
La Nina ◽  
The Indian Ocean ◽  
The Western Pacific

Abstract A feedback process of the Indian Ocean SST on ENSO is investigated by using observed data and atmospheric GCM. It is suggested that warming in the Indian Ocean produces an easterly wind stress anomaly over Indonesia and the western edge of the Pacific during the mature phase of El Niño. The anomalous easterly wind in the western Pacific during El Niño helps a rapid termination of El Niño and a fast transition to La Niña by generating upwelling Kelvin waves. Thus, warming in the Indian Ocean, which is a part of the El Niño signal, operates as a negative feedback mechanism to ENSO. This Indian Ocean feedback appears to operate mostly for relatively strong El Niños and results in a La Niña one year after the mature phase of the El Niño. This 1-yr period of phase transition implies a possible role of Indian Ocean–ENSO coupling in the biennial tendency of the ENSO. Atmospheric GCM experiments show that Indian Ocean SST forcing is mostly responsible for the easterly wind anomalies in the western Pacific.

scholarly journals STUDY ON VARIABILITY MECHANISM OF 1997/1998 ENSO IN PACIFIC OCEAN AND EASTERN PART OF INDONESIAN ARCHIPELAGO

2010 ◽  
Vol 3 (-) ◽  
Author(s):  
Luh Made Chandra ◽  
Astiti Ratnasari ◽  
I Gede Hendrawan ◽  
I Wayan Gede Astawa Karang ◽  
Yasuhiro Sugimori
Keyword(s):  
Pacific Ocean ◽  
Normal Condition ◽  
El Niño ◽  
El Nino ◽  
Surface Current ◽  
Western Pacific ◽  
Warm Water ◽  
El Niño Event ◽  
La Nina ◽  
The Western Pacific

El Nino-Southern Oscillation (ENSO) is one of the most important climate anomalies humans are concerned about. It brought many changes in physical of the ocean. This phenomenon causes changes in sea surface temperature (SST). During El-Nino condition, the SST is much warmer in eastern side of Pacific Ocean than normal condition, and during La-Nina event the SST in eastern Pacific Ocean is cooler than normal condition. From July 1997, the warm water has spread from the western Pacific Ocean towards the east and the winds in the western Pacific were blowing strongly towards the east, pushing the warm water eastward on December 1997 and January 1998. Strong La-Nina condition water extended farther westward than usual. In October 1997, during El-Nino event 1997, the SST in eastern part of Indonesia Archipelago was cooler. The varies of SST in PacificOcean during El-Nino 1997 was influenced the Indonesian Through Flow (ITF). During El-Nino event 1997, surface current flown strongly from Pacific Ocean to the Indian Ocean On the other hand, since March 1998 the surface current inversed from Indonesian Sea to the Pacific Ocean. Keywords: ENSO, SST, ITF.

scholarly journals Analysis of GPS water vapor variability during the 2011 La Niña event over the western Pacific Ocean

2013 ◽  
Vol 56 (3) ◽  
Author(s):  
Wayan Suparta ◽  
Ahmad Iskandar ◽  
Mandeep Singh Jit Singh ◽  
Mohd. Alauddin Mohd. Ali ◽  
Baharudin Yatim ◽  
...  
Keyword(s):  
Water Vapor ◽  
Pacific Ocean ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
Precipitable Water ◽  
La Niña ◽  
Western Pacific ◽  
Western Pacific Ocean ◽  
La Nina ◽  
The Western Pacific

<p>We analyzed the variability of global positioning system (GPS) water vapor during the 2011 La Niña events over the western Pacific Ocean. The precipitable water vapor (PWV) derived from the UMSK (Malaysia) GPS station was investigated and compared with four other selected GPS stations: NTUS (Singapore), PIMO (Philippines), BAKO (Indonesia) and TOW2 (Australia). Analysis of the correlation between PWV and the sea-surface temperature anomaly (SSTa) on a weekly basis for the three La Niña cases of January–February–March, August–September–October, and October–November–December was used as an indicator of the influence of the El Niño Southern Oscillation. A good relationship between GPS PWV and SSTa for the Niño 4 region, with correlation coefficients between -0.91 and -0.94, was observed for the August–September–October and October–November–December cases. During the 2011 La Niña events, the water vapor was seen to increase to about 8.39 mm for the October–November–December case, with decreases of about 4.20 mm for the remaining months, compared to the mean 2011 value. This implies that during these events, the precipitation in the western Pacific is increased, due to stronger easterly trade winds blowing along the eastern Pacific Ocean than along the western Pacific, and a mass of warm water moving westwards, thereby increasing the evaporation.</p>

scholarly journals Seasonal Modulations of El Niño–Related Atmospheric Variability: Indo–Western Pacific Ocean Feedback

2017 ◽  
Vol 30 (9) ◽  
pp. 3461-3472 ◽  
Author(s):  
Shang-Ping Xie ◽  
Zhen-Qiang Zhou
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
North Indian Ocean ◽  
Equatorial Pacific ◽  
Western Pacific ◽  
Northwest Pacific ◽  
Western Pacific Ocean ◽  
Combination Mode

The spatial structure of atmospheric anomalies associated with El Niño–Southern Oscillation varies with season because of the seasonal variations in sea surface temperature (SST) anomaly pattern and in the climatological basic state. The latter effect is demonstrated using an atmospheric model forced with a time-invariant pattern of El Niño warming over the equatorial Pacific. The seasonal modulation is most pronounced over the north Indian Ocean to northwest Pacific where the monsoonal winds vary from northeasterly in winter to southwesterly in summer. Specifically, the constant El Niño run captures the abrupt transition from a summer cyclonic to winter anticyclonic anomalous circulation over the northwest Pacific, in support of the combination mode idea that emphasizes nonlinear interactions of equatorial Pacific SST forcing and the climatological seasonal cycle. In post–El Niño summers when equatorial Pacific warming has dissipated, SST anomalies over the Indo–northwest Pacific Oceans dominate and anchor the coherent persisting anomalous anticyclonic circulation. A conceptual model is presented that incorporates the combination mode in the existing framework of regional Indo–western Pacific Ocean coupling.

scholarly journals Changes in Sea Salt Emissions Enhance ENSO Variability

2016 ◽  
Vol 29 (23) ◽  
pp. 8575-8588 ◽  
Author(s):  
Yang Yang ◽  
Lynn M. Russell ◽  
Sijia Lou ◽  
Maryam A. Lamjiri ◽  
Ying Liu ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
El Niño ◽  
El Nino ◽  
Sea Salt ◽  
La Niña ◽  
Western Pacific ◽  
Interannual Variations ◽  
Enso Variability ◽  
La Nina ◽  
The Tropical Pacific

Abstract Two 150-yr preindustrial simulations with and without interactive sea salt emissions from the Community Earth System Model (CESM) are performed to quantify the interactions between sea salt emissions and El Niño–Southern Oscillation (ENSO). Variations in sea salt emissions over the tropical Pacific Ocean are affected by changing wind speed associated with ENSO variability. ENSO-induced interannual variations in sea salt emissions result in decreasing (increasing) aerosol optical depth (AOD) by 0.03 over the equatorial central-eastern (western) Pacific Ocean during El Niño events compared to those during La Niña events. These changes in AOD further increase (decrease) radiative fluxes into the atmosphere by +0.2 (−0.4) W m−2 over the tropical eastern (western) Pacific. Thereby, sea surface temperature increases (decreases) by 0.2–0.4 K over the tropical eastern (western) Pacific Ocean during El Niño compared to La Niña events and enhances ENSO variability by 10%. The increase in ENSO amplitude is a result of systematic heating (cooling) during the warm (cold) phase of ENSO in the eastern Pacific. Interannual variations in sea salt emissions then produce the anomalous ascent (subsidence) over the equatorial eastern (western) Pacific between El Niño and La Niña events, which is a result of heating anomalies. Owing to variations in sea salt emissions, the convective precipitation is enhanced by 0.6–1.2 mm day−1 over the tropical central-eastern Pacific Ocean and weakened by 0.9–1.5 mm day−1 over the Maritime Continent during El Niño compared to La Niña events, enhancing the precipitation variability over the tropical Pacific.

scholarly journals Variations of Upper-Ocean Salinity Associated with ENSO from PEODAS Reanalyses

2016 ◽  
Vol 29 (6) ◽  
pp. 2077-2094 ◽  
Author(s):  
Mei Zhao ◽  
Harry H. Hendon ◽  
Yonghong Yin ◽  
Oscar Alves
Keyword(s):  
Barrier Layer ◽  
El Niño ◽  
El Nino ◽  
Western Pacific ◽  
Upper Ocean ◽  
Central Pacific ◽  
La Nina ◽  
Ocean Salinity ◽  
The Western Pacific ◽  
Extreme El Niño

Abstract Interannual variations of upper-ocean salinity in the tropical Pacific and relationships with ENSO are investigated using the Bureau of Meteorology (Australia) POAMA Ensemble Ocean Data Assimilation System (PEODAS) reanalyses. Empirical orthogonal function (EOF) analysis reveals the systematic evolution of salinity and temperature during ENSO. EOF1 and EOF2 of both temperature and salinity capture the mature phase of El Niño and the discharge and recharge phase, respectively. Typical El Niño and La Niña evolution captured by the leading pair of EOFs depicts eastward or westward migration of the eastern edge of the warm/fresh pool in the western Pacific. Increased or decreased freshness in the western Pacific mixed layer occurs in the recharge/discharge phase. EOF3 captures extreme El Niño, when the strong positive temperature anomaly extends to the South American coast and the fresh pool detaches from the western Pacific and shifts into the central Pacific. Large loadings on EOF3 occurred only during 1982/83 and 1997/98, which suggests that eastern Pacific El Niño is actually the exception, whereas moderate central Pacific El Niño and La Niña are more typical. The eastward expansion of the warm/fresh pool during El Niño is also associated with a continuous eastward displacement of the barrier layer, indicating an active role of the barrier layer not just at the onset of an event. The barrier layer and fresh pool shift much farther eastward during strong El Niño, which could contribute to the eastward shift of strong events. The prior enhancement of the barrier layer in the western Pacific is also more concentrated and stronger, which might portend development of extreme El Niño.

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