Contrast between the Climatic States of the Warm Pool in the Indian Ocean and in the Pacific Ocean

Based on the analysis of Levitus data, the climatic states of the warm pool in the Indian Ocean (WPIO) and in the Pacific Ocean (WPPO) are studied. It is found that WPIO has a relatively smaller area, a shallower bottom and a slightly lower seawater temperature than those of WPPO. The horizontal area at different depths, volumes, central positions, and bottom depths of both WPIO and WPPO show quite apparent signals of seasonal variation. The maximum amplitude of WPIO surface area’s seasonal variation is 58% larger over the annual mean value. WPIO’s maximum volume variation amplitude is 66% larger over the annual mean value. The maximum variation amplitudes of the surface area and volume of WPPO are 20. 9% and 20.6% larger over the annual mean value respectively. WPIO and WPPO show different temporal and spatial characteristics mainly due to the different wind fields and restriction of ocean basin geometry. For instance, seasonal northern displacement of WPIO is, to some extent, constrained by the basin of the Indian Ocean, while WPPO moves relatively freely in the longitudinal direction. The influence of WPIO and WPPO over the atmospheric motion must be quite different.

Roles of Equatorial Ocean Currents in Sustaining the Indian Ocean Dipole Peak

In this study,on the basis of the results of the European Centre for Medium-Range Weather Forecasts Ocean Reanalysis System 4,the response of equatorial ocean currents and their roles during the peak phase of the Indian Ocean Dipole(IOD)are comprehensively explored.During the IOD peak season,a series of ocean responses emerge.First,significant meridional divergence in the surface layer and convergence in the subsurface layer are found in the equatorial region.The equatorial easterly winds and offequatorial wind curl anomalies are found to be responsible for the divergence at 55°–80°E and the convergence at 70°–90°E.Second,the meridional divergence and convergence are found to favor a weakened Wyrtki jet(WJ)in the surface layer and an enhanced Equatorial Undercurrent(EUC)in the subsurface layer,respectively.Therefore,these ocean responses provide ocean positive feedback that sustains the IOD peak as the weakened WJ and enhanced EUC help maintain the zonal temperature gradient.Additionally,heat budget analyses indicate that the weakened WJ favors sea surface temperature anomaly warming in the western Indian Ocean,whereas the enhanced EUC maintains the sea surface temperature anomaly cooling in the eastern Indian Ocean.

Typical Surface Seasonal Circulation in the Indian Ocean Derived from Argos Floats

This study investigates the surface circulation in the Indian Ocean using Argos float data over the period 1979-2011.The Argos observations manifest some new phenomena.The climatological annual mean circulation shows that the surface current becomes much stronger after turning around in shore in the western Indian Ocean.In the tropical Indian Ocean,the Great Whirl(GW) to the east of Somalia develops quickly in spring(April-May) as the monsoon reverses to move northward,becoming strongest in summer(June-September) and disappearing in autumn(October-November).The west end of the Agulhas retroflection can reach 18°E,and it exhibits a seasonal variation.At approximately 90°E,the Agulhas Return Current combines with the eastward South Atlantic Current and finally joins the Antarctic Circumpolar Current.

Modeling the Hook Depth Distribution of Pelagic Longlining in the Equatorial Area of Indian Ocean

A survey was conducted in the equatorial area of Indian Ocean for a better understanding of the dynamics of hook depth distribution of pelagic longline fishery. We determined the relationship between hook depth and vertical shear of current coefficieney, wind speed, hook position code, sine of wind angle, sine of angle of attack and weight of messenger weight. We identified the hook depth models by the analysis of covariance with a general linear model. The results showed that the wind effect on the hook depth can be ignored from October to November in the survey area; the surface current effect on the hook depth can be ignored; the equato- rial undercurrent is the key factor for the hook depth in Indian Ocean; and there is a negative correlation between the hook depth and vertical shear of current and angle of attack. It was also found that the deeper the hook was set, the higher hook depth shoaling was. The proposed model improves the accuracy of the prediction of hook depth, which can be used to estimate the vertical distribution of pelagic fish in water column.

Variations in the eastern Indian Ocean warm pool and its relation to the dipole in the tropical Indian Ocean

Based on the monthly average SST and 850 hPa monthly average wind data,the seasonal,interannual and long-term variations in the eastern Indian Ocean warm pool(EIWP) and its relationship to the Indian Ocean Dipole(IOD),and its response to the wind over the Indian Ocean are analyzed in this study.The results show that the distribution range,boundary and area of the EIWP exhibited obviously seasonal and interannual variations associated with the ENSO cycles.Further analysis suggests that the EIWP had obvious long-term trend in its bound edge and area,which indicated the EIWP migrated westwards by about 14 longitudes for its west edge,southwards by about 5 latitudes for its south edge and increased by 3.52×106 km2 for its area,respectively,from 1950 to 2002.The correlation and composite analyses show that the anomalous westward and northward displacements of the EIWP caused by the easterly wind anomaly and the southerly wind anomaly over the eastern equatorial Indian Ocean played an important and direct role in the formation of the IOD.

From Security Governance to Geopolitical Rivalry:Iran-GCC Confrontation in the Red Sea and the Indian Ocean

This article aims to address the aspects of conflict between Iran and the GCC starting from the geographical location,focusing on the factors that influence the acquisition of power by different state actors in this maritime sphere.The purpose of the article is to uncover the significant factors that directly and indirectly affect the distribution of influence between Iran and the GCC countries in this strategic marine area through following different sub-goals that deal with the main elements regarding security,political and economic conditions within every country in that region,as well as among the various regional and international powers.The analysis reveals that the interests of the GCC in this strategic maritime outweighs the interests of Iran.In the meantime,Saudi Arabia and UAE consider this area a high security threat region,while Iran sees it as one of the multiple security axes that are associated with its interests.The security risks that threaten the Arab Gulf states because of the new political and economic relationship with Yemen due to the war,in addition to the declared and latent maneuvers of world powers from outside the region either to besiege the Gulf axis or to initiate alliances with the Gulf states,signify without doubt the strong future influence of this geographical spot for the GCC and the possibilities of conflict escalation between Iran and GCC.

THE EFFECTS OF SEA SURFACE TEMPERATURE OVER THE EQUATORIAL WESTERN PACIFIC AND THE INDIAN OCEAN ON THE ASIAN SUMMER MONSOON

In this paper, the p-σ five layer primitive equation model segmented by mountains and physical parameterizations including short wave radiation; long wave radiation; large-scale and convective condensation; heat and moisture transport from surface to the first model level is used. The horizonial resolution is 5° lat. ×5° long. with the integration region from 25°S to 55°N and from 5°W eastward to 175°W. The model was spun up with perpetual June boundary conditions and forcing starting with June zonal mean heights and geostrophic wind field. In order to investigate the effects of SST (sea surface tempefuture) over the equatorial Western Pacific and the Indian Ocean on the Asian summer monsoon, four sets of numerical experments with positive anomalies over the equatorial Western Pacific, and positive and negative anomalies over the Western Indian Ocean, and zonal mean SST (the control case) are performed. The experimental results show that the South Asian low in the lower troposphere and the anticyclone over the South Asia in the uppet troposphere intensified when positive SST anomalies over the equatorial Western Pacific is included. A statistical test method for simulations is proposed. Finally, the influence mechanism of the SST anomalies over the equatorial oceans is discussed. It is worth stressing that the effects of the SST over the equatorial oceans on the Asian summer monsoon can arise as a result of interaction of SST anomalies, atmospheric flow field and heat sources and sinks in the atmosphere.

INDIAN OCEAN DIPOLE AND ITS RELATIONSHIP WITH ENSO MODE

Near 100-year observed data sets are analyzed, and the results show that the variation of sea surface temperature(SST)in the equatorial Indian Ocean has a feature as a dipole oscillation.The situation of the dipole oscillation mainly shows the positive phase pattern(higher SST in the west and lower SST in the east than normal)and the negative phase pattern(higher SST in the east and lower SST in the west).The amplitude of the positive phase is larger than that of the negative phase.The dipole is stronger in September—November and weaker in January—April than in other months.It principally shows obviously inter-annual(4—5 year period)and inter-decadal variation(25—30 year period).Although the Indian Ocean dipole in the individual year seems to be independent of ENSO in the equatorial Pacific Ocean,in general,the Indian Ocean dipole has obviously negative correlation with the Pacific Ocean “dipole”(similar to the inverse phase of ENSO).The atmospheric zonal(Walker) circulation is fundamental for relating the two dipoles to each other.

Indonesia-UAE Relations in the Context of Regional Governance

This article analyzes the relationship between the United Arab Emirates(UAE)and Indonesia and describes its main drivers in the Regional Governance.The article provides an analysis of the main strategic interests of both Indonesia and the UAE considering four-overarching global and regional interests.It discusses reasons why this relationship will likely grow in the future,namely due to common interests in investment in Indonesia’s infrastructure,promoting moderate Islam and providing more ways to balance regional relations between the US,India and China.The article concludes with a synopsis of the key drivers of the UAE-Indonesian relationship and the role the Indian Ocean plays in enabling it.