Resonance of baroclinic waves in the tropical oceans: The Indian Ocean and the far western Pacific

2020 ◽  
Vol 89 ◽  
pp. 101119 ◽  
Author(s):  
Jean-Louis Pinault
Keyword(s):  
Indian Ocean ◽  
Western Pacific ◽  
Baroclinic Waves ◽  
Tropical Oceans ◽  
The Indian Ocean

Some new data on tropical western Pacific Ascidians

Zootaxa ◽  
2010 ◽  
Vol 2561 (1) ◽  
pp. 1 ◽  
Author(s):  
FRANÇOISE MONNIOT
Keyword(s):  
New Species ◽  
Indian Ocean ◽  
New Records ◽  
Western Pacific ◽  
Additional Species ◽  
Tropical Western Pacific ◽  
The Pacific ◽  
The Indian Ocean ◽  
Made In

Numerous collections of ascidians have been made in the Pacific and Indian Oceans but the inventory is far from complete. Each sampling provides new species. Two new didemnids are described here from Palau and Vanuatu. New records are given for 22 additional species with complementary descriptions and underwater photographs. The tropical ascidian fauna is highly diverse and successive new collections show that many of the species are not only widely distributed from the central to western Pacific but also common to the Indian Ocean.

scholarly journals Convective activities associated with intraseasonal variation over Sumatera, Indonesia, observed with the equatorial atmosphere radar

2004 ◽  
Vol 22 (11) ◽  
pp. 3899-3916 ◽  
Author(s):  
T. H. Seto ◽  
M. K. Yamamoto ◽  
H. Hashiguchi ◽  
S. Fukao
Keyword(s):  
Indian Ocean ◽  
Active Phase ◽  
Western Pacific ◽  
Mountainous Area ◽  
Local Circulation ◽  
Intraseasonal Variation ◽  
Cloud Clusters ◽  
Inactive Phase ◽  
The Indian Ocean ◽  
The Western Pacific

Abstract. The influence of intraseasonal variation (ISV) on convective activities over Sumatera (or Sumatra) is studied by using data derived from the Equatorial Atmosphere Radar (EAR), the Boundary Layer Radar (BLR), the surface weather station, the Geostationary Meteorological Satellite (GMS), and NCEP/NCAR reanalysis. In June 2002, convective activities over the Indian Ocean, the maritime continent, and the western Pacific were significantly modulated by the ISV. Blackbody brightness temperature observed by GMS (TBB) showed that two super cloud clusters (SCCs) developed over the Indian Ocean (70-90° E) in the first half of June 2002, and propagated eastward from the Indian Ocean to the western Pacific. Convective activities were enhanced over the western Pacific (130-160° E) in the latter half of June 2002. Convergence at 1000hPa, which prevailed over the Indian Ocean in the first half of June 2002, propagated eastward to the western Pacific in the latter half of June 2002. Zonal wind observed by EAR and surface pressure observed at the observation site suggested the existence of a Kelvin-wave-like structure of ISV. From temporal variations of TBB, zonal wind at 850hPa, and vertical shear of horizontal wind between 700 and 150hPa, we classified the observation periods into the inactive phase (1-9 June), active phase (10-19 June), and postwesterly wind burst phase of ISV (20-26 June). During the inactive phase of ISV, convective activities caused by local circulation were prominent over Sumatera. Results of radar observations indicated the dominance of convective rainfall events over the mountainous area of Sumatera during the inactive phase of ISV. During the active phase of the ISV, cloud clusters (CCs), which developed in the convective envelope of SCC with a period of 1-2 days, mainly induced the formation of convective activities over Sumatera. Results of radar observations indicated that both convective and stratiform rainfall events occurred over the mountainous area of Sumatera during the active phase of ISV. In the postwesterly wind burst phase of ISV, convective activities were suppressed over Sumatera. Features of convective activities found over Sumatera generally agreed well with those found in Tropical Ocean and Global Atmosphere/Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). However, local circulation played an important role in the formation of convective activities over Sumatera in the inactive phase of ISV.

scholarly journals Impact of the Madden–Julian Oscillation on Summer Rainfall in Southeast China

2009 ◽  
Vol 22 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Lina Zhang ◽  
Bizheng Wang ◽  
Qingcun Zeng
Keyword(s):  
Indian Ocean ◽  
Tropical Indian Ocean ◽  
Summer Rainfall ◽  
Western Pacific ◽  
Madden Julian Oscillation ◽  
Energy Propagation ◽  
Southeast China ◽  
The Indian Ocean ◽  
The Impact ◽  
The Western Pacific

Abstract The impact of the Madden–Julian oscillation (MJO) on summer rainfall in Southeast China is investigated using the Real-time Multivariate MJO (RMM) index and the observational rainfall data. A marked transition of rainfall patterns from being enhanced to being suppressed is found in Southeast China (east of 105°E and south of 35°N) on intraseasonal time scales as the MJO convective center moves from the Indian Ocean to the western Pacific Ocean. The maximum positive and negative anomalies of regional mean rainfall are in excess of 10% relative to the climatological regional mean. Such different rainfall regimes are associated with the corresponding changes in physical fields such as the western Pacific subtropical high (WPSH), moisture, and vertical motions. When the MJO is mainly over the Indian Ocean, the WPSH shifts farther westward, and the moisture and upward motions in Southeast China are increased. In contrast, when the MJO enters the western Pacific, the WPSH retreats eastward, and the moisture and upward motions in Southeast China are decreased. It is suggested that the MJO may influence summer rainfall in Southeast China through remote and local dynamical mechanisms, which correspond to the rainfall enhancement and suppression, respectively. The remote role is the energy propagation of the Rossby wave forced by the MJO-related heating over the Indian Ocean through the low-level westerly waveguide from the tropical Indian Ocean to Southeast China. The local role is the northward shift of the upward branch of the anomalous meridional circulation when the MJO is over the western Pacific, which causes eastward retreat of the WPSH and suppressed moisture transport toward Southeast China.

Precursor Environmental Conditions Associated with the Termination of Madden–Julian Oscillation Events

2015 ◽  
Vol 72 (5) ◽  
pp. 1908-1931 ◽  
Author(s):  
Justin P. Stachnik ◽  
Duane E. Waliser ◽  
Andrew J. Majda
Keyword(s):  
Indian Ocean ◽  
Environmental Conditions ◽  
Warm Pool ◽  
Western Pacific ◽  
Specific Humidity ◽  
Advection Equation ◽  
Local Domain ◽  
Madden Julian Oscillation ◽  
Budget Analysis ◽  
The Indian Ocean

Abstract This study presents an analysis of the precursor environmental conditions related to the termination of Madden–Julian oscillation (MJO) events. A simple climatology is created using a real-time MJO monitoring index, documenting the locations and frequencies of MJO decay. Lead–lag composites of several atmospheric variables including temperature, moisture, and intraseasonal wind anomalies are generated from three reanalyses. There is remarkable agreement among the datasets with long-term, lower-tropospheric moisture deficits over the local domain best identifying termination events over the Indian Ocean. MJO termination in the Indian Ocean is also linked to a northward shift of the intertropical convergence zone (ITCZ) with possible lead times as much as 20 days prior to MJO decay. Statistically significant differences in the low-level vertical velocity and specific humidity are also identified more than 10 days in advance of MJO termination events in the western Pacific, though the differences here are more symmetric about the equator. Unlike the Indian Ocean and western Pacific, MJOs that terminate over the Maritime Continent appear to be related to their own intensity rather than the downstream conditions. As such, only the strongest MJOs tend to propagate into the warm pool region. Finally, a budget analysis is performed on the three-dimensional moisture advection equation in order to better elucidate what time scales and physical mechanisms are most important for MJO termination. The combination of intraseasonal vertical circulation anomalies coupled with the mean-state specific humidity best explain the anomalous moisture patterns associated with MJO termination, suggesting that the downstream influence of the MJO circulation can eventually lead to its future demise.

The Influence of Atmospheric Convection on the Interaction between the Indian Ocean and ENSO

2017 ◽  
Vol 30 (24) ◽  
pp. 10155-10178 ◽  
Author(s):  
Claudia E. Wieners ◽  
Henk A. Dijkstra ◽  
Will P. M. de Ruijter
Keyword(s):  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Western Pacific ◽  
Water Volume ◽  
Maritime Continent ◽  
Enso Events ◽  
The Indian Ocean ◽  
The Western Pacific

In recent years it has been proposed that a negative (positive) Indian Ocean dipole (IOD) in boreal autumn favors an El Niño (La Niña) at a lead time of 15 months. Observational analysis suggests that a negative IOD might be accompanied by easterly anomalies over the western Pacific. Such easterlies can enhance the western Pacific warm water volume, thus favoring El Niño development from the following boreal spring onward. However, a Gill-model response to a negative IOD forcing would lead to nearly zero winds over the western Pacific. The authors hypothesize that a negative IOD—or even a cool western Indian Ocean alone—leads to low-level air convergence and hence enhanced convectional heating over the Maritime Continent, which in turn amplifies the wind convergence so as to cause easterly winds over the western Pacific. This hypothesis is tested by coupling an idealized Indian Ocean model and a convective feedback model over the Maritime Continent to the Zebiak–Cane model. It is found that, for a sufficiently strong convection feedback, a negative (positive) IOD indeed forces easterlies (westerlies) over the western Pacific. The contribution from the eastern IOD pole dominates. IOD variability is found to destabilize the El Niño–Southern Oscillation (ENSO) mode, whereas Indian Ocean basinwide warming (IOB) variability dampens ENSO, even in the presence of convection. The influence of the Indian Ocean on the spectral properties of ENSO is dominated by the IOB, while the IOD is a better predictor for individual ENSO events.

scholarly journals Phylogeography of Blue Corals (Genus Heliopora) Across the Indo-West Pacific

2021 ◽  
Vol 8 ◽  
Author(s):  
Hiroki Taninaka ◽  
Davide Maggioni ◽  
Davide Seveso ◽  
Danwei Huang ◽  
Abram Townsend ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Phylogenetic Trees ◽  
Kuroshio Current ◽  
Western Pacific ◽  
Valid Species ◽  
West Pacific ◽  
Malay Archipelago ◽  
The Indian Ocean ◽  
Current Region ◽  
The Kuroshio

Species delimitation of corals is one of the most challenging issues in coral reef ecology and conservation. Morphology can obscure evolutionary relationships, and molecular datasets are consistently revealing greater within-species diversity than currently understood. Most phylogenetic studies, however, have examined narrow geographic areas and phylogeographic expansion is required to obtain more robust interpretations of within- and among- species relationships. In the case of the blue coral Heliopora, there are currently two valid species (H. coerulea and H. hiberniana) as evidenced by integrated genetic and morphological analyses in northwestern Australia. There are also two distinct genetic lineages of H. coerulea in the Kuroshio Current region that are morphologically and reproductively different from each other. Sampling from all Heliopora spp. across the Indo-Pacific is essential to obtain a more complete picture of phylogeographic patterns. To examine phylogenetic relationships within the genus Heliopora, we applied Multiplexed inter simple sequence repeat (ISSR) Genotyping by sequencing (MIG-seq) on > 1287 colonies across the Indo-West Pacific. Maximum likelihood phylogenetic trees indicated the examined Heliopora samples comprise three genetically distinct groups: H. coerulea group, H. hiberniana group, and a new undescribed Heliopora sp. group with further subdivisions within each group. Geographic structuring is evident among the three species with H. hiberniana group found in the Indo-Malay Archipelago and biased toward the Indian Ocean whilst Heliopora sp. was only found in the Kuroshio Current region and Singapore, indicating that this taxon is distributed in the western Pacific and the Indo-Malay Archipelago. Heliopora coerulea has a wider distribution, being across the Indian Ocean and western Pacific. This study highlights the effectiveness of phylogenetic analysis using genome-wide markers and the importance of examining populations across their distribution range to understand localized genetic structure and speciation patterns of corals.

scholarly journals Maritime Security and Geopolitics in the Indo-Pacific Region

2019 ◽  
Vol 18 (4) ◽  
pp. 71-86
Author(s):  
Gurpreet Singh Khurana
Keyword(s):  
Indian Ocean ◽  
National Security ◽  
Maritime Security ◽  
Western Pacific ◽  
Economic Power ◽  
Centre Of Gravity ◽  
Security Environment ◽  
The Us ◽  
The Indian Ocean ◽  
The Western Pacific

The centre-of-gravity of world‘s economic power is shifting eastwards to the ‗Indo-Pacific‘, a maritime-configured macro-region that spans the maritime underbelly of Asia connecting the Indian and the western Pacific oceans. The security environment in the Indian Ocean and the western Pacific are different; nonetheless, strong maritime security linkages emerging between the two oceans has led to the reincarnation of the concept of ‗Indo-Pacific‘. Since the turn of the 21st century, new maritime insecurities have taken root, including in terms of China‘s revisionist positions on the established maritime order. Notwithstanding the US response in the western Pacific and the recent articulation of its ‗Indo-Pacific‘ strategy, it is unclear how the regional countries and the major regional stakeholders willmanage to address the emerging maritime insecurities in the Indian Ocean, including in terms of China‘s expanding politico-military footprint. This paper attempts to examine the security environment and geopolitics in the Indo-Pacific in context of India‘s national security interests.

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