Indian Ocean Variability in the GFDL Coupled Climate Model

2007 ◽  
Vol 20 (13) ◽  
pp. 2895-2916 ◽  
Author(s):  
Qian Song ◽  
Gabriel A. Vecchi ◽  
Anthony J. Rosati
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Deep Convection ◽  
Warm Pool ◽  
Surface Winds ◽  
Pacific Warm Pool ◽  
El Niño Events ◽  
The Indian Ocean ◽  
El Nino Events

Abstract The interannual variability of the Indian Ocean, with particular focus on the Indian Ocean dipole/zonal mode (IODZM), is investigated in a 250-yr simulation of the GFDL coupled global general circulation model (CGCM). The CGCM successfully reproduces many fundamental characteristics of the climate system of the Indian Ocean. The character of the IODZM is explored, as are relationships between positive IODZM and El Niño events, through a composite analysis. The IODZM events in the CGCM grow through feedbacks between heat-content anomalies and SST-related atmospheric anomalies, particularly in the eastern tropical Indian Ocean. The composite IODZM events that co-occur with El Niño have stronger anomalies and a sharper east–west SSTA contrast than those that occur without El Niño. IODZM events, whether or not they occur with El Niño, are preceded by distinctive Indo-Pacific warm pool anomaly patterns in boreal spring: in the central Indian Ocean easterly surface winds, and in the western equatorial Pacific an eastward shift of deep convection, westerly surface winds, and warm sea surface temperature. However, delayed onsets of the anomaly patterns (e.g., boreal summer) are often not followed by IODZM events. The same anomaly patterns often precede El Niño, suggesting that the warm pool conditions favorable for both IODZM and El Niño are similar. Given that IODZM events can occur without El Niño, it is proposed that the observed IODZM–El Niño relation arises because the IODZM and El Niño are both large-scale phenomena in which variations of the Indo-Pacific warm pool deep convection plays a central role. Yet each phenomenon has its own dynamics and life cycle, allowing each to develop without the other. The CGCM integration also shows substantial decadal modulation of the occurrence of IODZM events, which is found to be not in phase with that of El Niño events. There is a weak, though significant, negative correlation between the two. Moreover, the statistical relationship between the IODZM and El Niño displays strong decadal variability.

scholarly journals Differences in the Initiation and Development of the Madden–Julian Oscillation over the Indian Ocean Associated with Two Types of El Niño

2017 ◽  
Vol 30 (4) ◽  
pp. 1397-1415 ◽  
Author(s):  
Pang-Chi Hsu ◽  
Ting Xiao
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Radiative Heating ◽  
Madden Julian Oscillation ◽  
Cp El Niño ◽  
El Niño Events ◽  
The Indian Ocean ◽  
Ep El Niño ◽  
El Nino Events

Abstract The influences of different types of Pacific warming, often classified as the eastern Pacific (EP) and central Pacific (CP) El Niño events, on Madden–Julian oscillation (MJO) activity over the Indian Ocean were investigated. Accompanied by relatively unstable (stable) atmospheric stratification induced by enhanced (reduced) moisture and moist static energy (MSE) in the lower troposphere, strengthened (weakened) MJO convection was observed in the initiation and eastward-propagation stages during CP (EP) El Niño events. To examine the key processes resulting in the differences in low-level moistening and column MSE anomalies over the Indian Ocean associated with the two types of El Niño, the moisture and column MSE budget equations were diagnosed using the reanalysis dataset ERA-Interim. The results indicate that the enhanced horizontal advection in the CP El Niño years plays an important role in causing a larger moisture and MSE growth rate over the MJO initiation area during CP El Niño events than during EP El Niño events. The increases in horizontal moisture and MSE advection primarily result from advection by mean flow across the enhanced intraseasonal moisture and MSE gradient, as well as by intraseasonal circulation across the mean moisture and MSE gradient associated with the CP El Niño. In the eastward development stage, the enhanced preconditioning comes from positive moisture and MSE advection anomalies in the CP El Niño events. Meanwhile, the strengthened MJO-related convection over the central-eastern Indian Ocean is maintained by increased atmospheric radiative heating and surface latent heat flux during the CP El Niño compared to the EP El Niño events.

scholarly journals Warming Trend of the Indian Ocean SST and Indian Ocean Dipole from 1880 to 2004*

2008 ◽  
Vol 21 (10) ◽  
pp. 2035-2046 ◽  
Author(s):  
Chie Ihara ◽  
Yochanan Kushnir ◽  
Mark A. Cane
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Indian Ocean Dipole ◽  
El Nino ◽  
Warming Trend ◽  
Positive Events ◽  
The Pacific ◽  
El Niño Events ◽  
The Indian Ocean ◽  
El Nino Events

Abstract The state of the Indian Ocean dipole representing the SST anomaly difference between the western and southeastern regions of the ocean is investigated using historical SST reconstructions from 1880 to 2004. First, the western and eastern poles of the SST-based dipole mode index are analyzed separately. Both the western and eastern poles display warming trends over this period, particularly after the 1950s. The western pole tends to be anomalously colder than the eastern pole from 1880 to 1919, whereas in the interval 1950–2004 the SST anomalies over the western pole are comparable to those over the eastern pole though there are occasional outliers where the eastern pole is anomalously colder than the western pole. The tendencies of the occurrences of positive and negative dipole events in September–November show three distinct regimes during the period analyzed. In 1880–1919, negative dipole events associated with La Niña events occur more frequently than positive events. In 1920–49, some weak positive events occur relatively independently of El Niño events over the Pacific. The period of 1960–2004 is characterized by strong and frequent occurrences of positive events associated with El Niño events.

scholarly journals Studies of the seasonal prediction of heavy late spring rainfall over southeastern China

2021 ◽  
Author(s):  
Shouwen Zhang ◽  
Hui Wang ◽  
Hua Jiang ◽  
Wentao Ma
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Lead Time ◽  
Heavy Rainfall ◽  
El Nino ◽  
Late Spring ◽  
Southeastern China ◽  
River Region ◽  
El Niño Events ◽  
El Nino Events

AbstractThe late spring rainfall may account for 15% of the annual total rainfall, which is crucial to early planting in southeastern China. A better understanding of the precipitation variations in the late spring and its predictability not only greatly increase our knowledge of related mechanisms, but it also benefits society and the economy. Four models participating in the North American Multi-Model Ensemble (NMME) were selected to study their abilities to forecast the late spring rainfall over southeastern China and the major sources of heavy rainfall from the perspective of the sea surface temperature (SST) field. We found that the models have better abilities to forecast the heavy rainfall over the middle and lower reaches of the Yangtze River region (MLYZR) with only a 1-month lead time, but they failed for a 3-month lead time since the occurrence of the heavy rainfall was inconsistent with the observations. The observations indicate that the warm SST anomalies in the tropical eastern Indian Ocean are vital to the simultaneously heavy rainfall in the MLYZR in May, but an El Niño event is not a necessary condition for determining the heavy rainfall over the MLYZR. The heavy rainfall over the MLYZR in May is always accompanied by warming of the northeastern Indian Ocean and of the northeastern South China Sea (NSCS) from April to May in the models and observations, respectively. In the models, El Niño events may promote the warming processes over the northeastern Indian Ocean, which leads to heavy rainfall in the MLYZR. However, in the real world, El Niño events are not the main reason for the warming of the NSCS, and further research on the causes of this warming is still needed.

The Extreme El Niño Events Suppressing the Intraseasonal Variability in the Eastern Tropical Indian Ocean

2020 ◽  
Vol 50 (8) ◽  
pp. 2359-2372
Author(s):  
Gengxin Chen ◽  
Dongxiao Wang ◽  
Weiqing Han ◽  
Ming Feng ◽  
Fan Wang ◽  
...  
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Intraseasonal Variability ◽  
Tropical Indian Ocean ◽  
Ocean Dynamics ◽  
El Niño Events ◽  
Extreme El Niño ◽  
El Nino Events

AbstractIn the eastern tropical Indian Ocean, intraseasonal variability (ISV) affects the regional oceanography and marine ecosystems. Mooring and satellite observations documented two periods of unusually weak ISV during the past two decades, associated with suppressed baroclinic instability of the South Equatorial Current. Regression analysis and model simulations suggest that the exceptionally weak ISVs were caused primarily by the extreme El Niño events and modulated to a lesser extent by the Indian Ocean dipole. Additional observations confirm that the circulation balance in the Indo-Pacific Ocean was disrupted during the extreme El Niño events, impacting the Indonesian Throughflow Indian Ocean dynamics. This research provides substantial evidence for large-scale modes modulating ISV and the abnormal Indo-Pacific dynamical connection during extreme climate modes.

Two Types of El Niño Events: Cold Tongue El Niño and Warm Pool El Niño

2009 ◽  
Vol 22 (6) ◽  
pp. 1499-1515 ◽  
Author(s):  
Jong-Seong Kug ◽  
Fei-Fei Jin ◽  
Soon-Il An
Keyword(s):  
Spatial Patterns ◽  
El Niño ◽  
El Nino ◽  
Warm Pool ◽  
Discharge Process ◽  
Cold Tongue ◽  
El Niño Events ◽  
Sst Anomaly ◽  
Sst Anomalies ◽  
El Nino Events

Abstract In this study, two types of El Niño events are classified based on spatial patterns of the sea surface temperature (SST) anomaly. One is the cold tongue (CT) El Niño, which can be regarded as the conventional El Niño, and the other the warm pool (WP) El Niño. The CT El Niño is characterized by relatively large SST anomalies in the Niño-3 region (5°S–5°N, 150°–90°W), while the WP El Niño is associated with SST anomalies mostly confined to the Niño-4 region (5°S–5°N, 160°E–150°W). In addition, spatial patterns of many atmospheric and oceanic variables are also distinctively different for the two types of El Niño events. Furthermore, the difference in the transition mechanism between the two types of El Niño is clearly identified. That is, the discharge process of the equatorial heat content associated with the WP El Niño is not efficient owing to the spatial structure of SST anomaly; as a result, it cannot trigger a cold event. It is also demonstrated that zonal advective feedback (i.e., zonal advection of mean SST by anomalous zonal currents) plays a crucial role in the development of a decaying SST anomaly associated with the WP El Niño, while thermocline feedback is a key process during the CT El Niño.

scholarly journals EFFECTS OF DIPOLE MODE AND EL-NINO EVENTS ON CATCHES OF YELLOWFIN TUNA (Thunnus albacares) IN THE EASTERN INDIAN OCEAN OFF WEST JAVA

2015 ◽  
Vol 21 (2) ◽  
pp. 75 ◽  
Author(s):  
Khairul Amri ◽  
Ali Suman ◽  
Hari Eko Irianto ◽  
Wudianto Wudianto
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Yellowfin Tuna ◽  
Environmental Data ◽  
Thunnus Albacares ◽  
Dipole Mode ◽  
Indian Ocean Dipole Mode ◽  
El Niño Events ◽  
El Nino Events

The effects of Indian Ocean Dipole Mode and El Niño–Southern Oscillation events on catches of YellowfinTuna (<em>Thunnus albacares</em>) in the Eastern Indian Ocean (EIO) off Java were evaluated through the use of remotely sensed environmental data (sea surface temperature/SST and chlorophyll-a concentration/SSC) and Yellowfin Tuna catch data. Analyses were conducted for the period of 2003–2012, which included the strong positive dipole mode event in association with weak El-Nino 2006.Yellowfin Tuna catch data were taken from Palabuhanratu landing place and remotely sensed environmental data were taken from MODIS-Aqua sensor.The result showed that regional climate anomaly Indian Ocean Dipole Mode influenced Yellowfin Tuna catch and its composition. The catches per unit effort (CPUE) of Thunnus alabacares in the strong positive dipole mode event in 2006 and weak El-Nino events in 2011 and 2012 was higher. The increase patern of CPUE followed the upwelling process, started from May-June achieved the peak between September-October.Very high increase in CPUE when strong positive dipole mode event (2006) and a weak El-Nino events (2011 and 2012) had a relation with the increase in the distribution of chlorophyll-a indicating an increase in the abundance of phytoplankton (primary productivity) due to upwelling. In contrast, yellowfin tuna CPUE is very low at the La-Nina event (2005), though as the dominant catch when compared to others.

scholarly journals On the role of the south Pacific subtropical high at the onset of El Niño events

2018 ◽  
Author(s):  
Youjia Zou ◽  
Xiangying Xi
Keyword(s):  
El Niño ◽  
El Nino ◽  
South Pacific ◽  
Warm Pool ◽  
Equatorial Pacific ◽  
Subtropical High ◽  
Trade Winds ◽  
Southward Shift ◽  
El Niño Events ◽  
El Nino Events

Abstract. Previous studies have suggested that an eastward propagation of the warm pool in the western Pacific during El Niño events may be induced by a weakening of the easterly Trade Winds (Alexander et al., 2002; Bjerknes, 1969). However, the dynamic mechanism of the Trade Winds weakening is not well understood. Here we use a model and other published proxy records to demonstrate that the anomalous southward shift of the south Pacific subtropical high (SPSH) may play a crucial role at the onset of El Niño events. By analyzing the relationship between the Trade Winds, the Equatorial Currents, the Eastern Boundary Currents and the SPSH, we find that an anomalous southward shift of the SPSH can result in a weakening of the SE Trade Winds and a southward intrusion of the NE Trade Winds, leading to a southward migration of the Trade Wind-induced Equatorial Currents, including the Equatorial Countercurrent (from ~5°–8° N to ~0°). The warm pool in the western equatorial Pacific is therefore forced to propagate eastward by the enhanced Equatorial Countercurrent and, thus, a warm phase in the central or the eastern equatorial Pacific. Moreover, the equatorward upwelling in the eastern South Pacific, usually recurving along the equator, shifts southward along with the SPSH, in turn diverts towards the west at ~15° S to feed the westward South Equatorial Currents, resulting in a failure of cooling sea surface in the eastern tropical Pacific, thus a flattening of the thermocline. The model experiments indicate that the meridional position and intensity of the Equatorial Countercurrent in the Pacific are some of the determining factors in giving rise to El Niño diversity, suggesting that there should be more frequent warm events due to a meridional expansion of the warm pool under global warming.

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