scholarly journals Satellite-Observed Multi-Scale Variability of Sea Surface Chlorophyll-a Concentration along the South Coast of the Sumatra-Java Islands

2021 ◽  
Vol 13 (14) ◽  
pp. 2817
Author(s):  
Tengfei Xu ◽  
Zexun Wei ◽  
Shujiang Li ◽  
Raden Dwi Susanto ◽  
Nyoman Radiarta ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Chlorophyll A ◽  
Sea Surface ◽  
South Coast ◽  
Subsurface Water ◽  
Ekman Pumping ◽  
The South ◽  
Chlorophyll A Concentration ◽  
Multi Scale ◽  
The Indian Ocean

The southern coast of Java is known as one of the most productive fishing grounds for tuna, feeding by nutrient-rich water along the coast caused by the subsurface water upwelling. This primary productivity can be evidenced by the high sea surface chlorophyll-a concentration (SSC). Based on satellite remote sensing products, we investigate the multi-scale variability in SSC along the Sumatra-Java coast. The results show that seasonal variability of SSCs is primarily due to monsoon-driven upwelling and rainfall in the Indian Ocean and Indonesian seas sides of the Sumatra and Java Islands, respectively. Local Ekman pumping plays a secondary role, while rainfall input to the ocean has little effect. Coastally trapped Kelvin waves and mesoscale eddies are responsible for the intraseasonal SSC anomalies in regions along the south coast of Java and off the Sunda and Lombok Straits, respectively. The interannual variability in SSC is caused by the anomalous upwelling related to the Indian Ocean Dipole. There was a weak increasing trend of ~0.1–0.2 mg/m3 per decade, above the global averaged trend, which may be related to enhanced local Ekman pumping. These analyses provide an overall description of SSC variations based on satellite observations; however, further investigations based on in situ observations are needed to achieve better quantification.

Interannual Variability in Sea Surface Height at Southern Midlatitudes of the Indian Ocean

2021 ◽  
Vol 51 (5) ◽  
pp. 1595-1609
Author(s):  
Motoki Nagura ◽  
Michael J. McPhaden
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Sea Surface Height ◽  
Wind Forcing ◽  
Sea Surface ◽  
The South ◽  
South Indian Ocean ◽  
Eastern Boundary ◽  
South Indian ◽  
The Indian Ocean

AbstractThis study examines interannual variability in sea surface height (SSH) at southern midlatitudes of the Indian Ocean (10°–35°S). Our focus is on the relative role of local wind forcing and remote forcing from the equatorial Pacific Ocean. We use satellite altimetry measurements, an atmospheric reanalysis, and a one-dimensional wave model tuned to simulate observed SSH anomalies. The model solution is decomposed into the part driven by local winds and that driven by SSH variability radiated from the western coast of Australia. Results show that variability radiated from the Australian coast is larger in amplitude than variability driven by local winds in the central and eastern parts of the south Indian Ocean at midlatitudes (between 19° and 33°S), whereas the influence from eastern boundary forcing is confined to the eastern basin at lower latitudes (10° and 17°S). The relative importance of eastern boundary forcing at midlatitudes is due to the weakness of wind stress curl anomalies in the interior of the south Indian Ocean. Our analysis further suggests that SSH variability along the west coast of Australia originates from remote wind forcing in the tropical Pacific, as is pointed out by previous studies. The zonal gradient of SSH between the western and eastern parts of the south Indian Ocean is also mostly controlled by variability radiated from the Australian coast, indicating that interannual variability in meridional geostrophic transport is driven principally by Pacific winds.

INDIAN OCEAN TSUNAMI ON 26 DECEMBER 2004: NUMERICAL MODELING OF INUNDATION IN THREE CITIES ON THE SOUTH COAST OF SRI LANKA

2008 ◽  
Vol 02 (02) ◽  
pp. 133-155 ◽  
Author(s):  
J. J. WIJETUNGE ◽  
XIAOMING WANG ◽  
PHILIP L.-F. LIU
Keyword(s):  
Sri Lanka ◽  
Indian Ocean ◽  
Maximum Flow ◽  
South Coast ◽  
Indian Ocean Tsunami ◽  
The South ◽  
Tsunami Inundation ◽  
Inundation Maps ◽  
The Indian Ocean ◽  
2004 Tsunami

The 2004 Indian Ocean tsunami caused enormous loss of lives and damage to property in Sri Lanka and in several other countries bordering the Indian Ocean. One way of mitigating potential loss of lives from a similar event in the future is through early warning and quick evacuation of vulnerable coastal communities to safer areas, and such evacuation planning is usually carried out based on inundation maps. Accordingly, the present paper outlines the numerical modelling carried out to develop tsunami inundation maps on a grid of 10 m resolution for three cities on the south coast of Sri Lanka. The results give the tsunami arrival time contours and the spatial distribution of the extent of inundation, the maximum flow velocities as well as the hydrodynamic force in these three cities due to an event similar to the 2004 tsunami.

Role of friction and orography in the Asian-African monsoonal system

2020 ◽  
Author(s):  
Giovanni Dalu ◽  
Marco Gaetani ◽  
Cyrille Flamant ◽  
Marina Baldi
Keyword(s):  
Indian Ocean ◽  
West African Monsoon ◽  
Tropical Indian Ocean ◽  
Western Indian Ocean ◽  
Ekman Pumping ◽  
The South ◽  
The West ◽  
Impermeable Barrier ◽  
The Indian Ocean ◽  
Marine Air

<p>The West African monsoon (WAM) originates in the Gulf of Guinea when the intertropical convergence zone (ITCZ) makes its landfall; whilst, the south Asian monsoon (SAM) originates in the Indian ocean when the ITCZ crosses the equator. The monsoonal dynamics are here studied after landfall using Gill’s tropospheric model with an implanted Ekman frictional layer (EFL). Ekman pumping increases low level convergence, making the lower monsoonal cyclone deeper and more compact that the upper anticyclone, by transferring tropospheric vorticity into the EFL. In the upper troposphere, air particles spiral-out anticyclonically away from the monsoons, subsiding over the Tropical Atlantic, the Tropical Indian ocean, or transiting into the southern hemisphere across the equator. Whilst marine air particles spiral-in cyclonically towards the WAM or the SAM, the latter appears to be a preferred ending destination in the absence of orography. The Himalayas introduced as a barrier to the monsoonal winds, strengthen the tropospheric winds by tightening the isobars. The Somali mountains (SMs), introduced as a barrier to the Ekman winds, separates the WAM and the SAM catch basins; thus, the Atlantic air particles converge towards the WAM and the Indian ocean particles converge towards the SAM. The Indian Ghats (IGs), introduced as a semi-impermeable barrier to the Ekman winds, deflect the marine air particles originated in the western Indian ocean towards the south-eastern flank of the SAM. In short, an upper single anticyclone encircles both monsoons; the Himalayas strengthen the upper-level winds by increasing the pressure gradients; the SMs split the EFL cyclone, keeping the marine air particles to the west of SMs in the WAM basin and the particles to the east of SMs in the SAM basin; the IGs guides transmit the air particles, deflecting them towards Bangladesh.</p>

scholarly journals Impact of Climate Change on Sea Surface Temperature and Chlorophyll-a Concentration in South Sukabumi Waters

2021 ◽  
Vol 19 (2) ◽  
pp. 393-398
Author(s):  
Mamat Suhermat ◽  
Muhammad Dimyati ◽  
S. Supriatna ◽  
M. Martono
Keyword(s):  
Climate Change ◽  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Indian Ocean Dipole ◽  
Sea Surface ◽  
Linear Regression Method ◽  
Chlorophyll A Concentration ◽  
Impact Of Climate Change

Indonesia territorial waters are very vulnerable to the impacts of climate change. Research about the variations of sea surface temperature and chlorophyll-a concentration in the southern waters of Java has been undertaken by several researchers. However, the research is still in the scope of regional scale south of Java. This research was conducted to determine the impact of climate change on sea surface temperature and chlorophyll-a concentration in Sukabumi waters. The data used consisted of IOD index anomalies, sea surface temperature and monthly chlorophyll-a concentrations from December 2002 to November 2020. Descriptive analysis was used to determine seasonal and inter-annual variability and linear regression method was used to analyze trends in changes in sea surface temperature (SST) and chlorophyll-a concentration. The results showed that the seasonal variation was influenced by the monsoon, while the interannual variation was influenced by the Indian Ocean Dipole. Climate change causes SST and chlorophyll-a concentrations to increase. In the 2003-2020 time period, SPL increased by 0.08 °C and an increase in chlorophyll-a concentration by 0.03 mg/ m3. ABSTRAKPerairan selatan Sukabumi yang berhadapan langsung dengan samudera Hindia sangat rentan terhadap dampak perubahan iklim. Penelitian mengenai variasi suhu permukaan laut dan konsentrasi klorofil-a di perairan selatan Jawa sudah dilakukan oleh beberapa peneliti sebelumnya. Namun penelitian tersebut masih dalam lingkup skala regional selatan Jawa. Penelitian ini dilakukan untuk mengetahui dampak perubahan iklim terhadap suhu permukaan laut dan konsentrasi klorofil-a di Perairan selatan Sukabumi. Data-data yang digunakan terdiri dari indeks IOD, suhu permukaan laut dan konsentrasi klorofil-a bulanan periode Desember 2002 hingga November 2020. Metode yang digunakan dalam penelitian ini adalah analisis deskripsi dan regresi linier. Hasil penelitian menunjukkan bahwa variasi musiman suhu permukaan laut dan konsentrasi klorofil-a di perairan ini dipengaruhi oleh monsun, sedangkan variasi antar tahunan dipengaruhi oleh Indian Ocean Dipole. Perubahan iklim menyebabkan suhu permukaan laut dan konsentrasi klorofil-a mengalami kenaikan. Dalam periode waktu 2003-2020 suhu permukaan laut mengalami kenaikan sebesar 0,08°C dan kenaikan konsentrasi klorofil-a sebesar 0,03 mg/m3.

The Zoroastrian fire temple in the ex-Portuguese colony of Diu, India

2003 ◽  
Vol 13 (1) ◽  
pp. 1-20
Author(s):  
Mehrdad Shokoohy
Keyword(s):  
Nineteenth Century ◽  
Twentieth Century ◽  
Seventeenth Century ◽  
Sixteenth Century ◽  
Indian Ocean ◽  
The Other ◽  
South Coast ◽  
The South ◽  
The Indian Ocean ◽  
The Town

AbstractThe ex-Portuguese town of Diu on the island with the same name off the south coast of Saurashtra, Gujarat, is one of the best-preserved and yet least-studied Portuguese colonial towns. Diu was the last of the Portuguese strongholds in India, the control of which was finally achieved in 1539 after many years of futile struggle and frustrating negotiations with the sultanate of Gujarat. During the late sixteenth and seventeenth century Diu remained a main staging post for Portuguese trade in the Indian Ocean, but with the appearance of the Dutch, and later the French and British, on the scene the island gradually lost its strategic importance. The town was subjected to little renovation during the nineteenth century while in the twentieth century Diu was no more than an isolated Portuguese outpost with meagre trade until it was taken over by India in 1961. As a result, unlike the other former Portuguese colonies in India – Daman and Goa – Diu has preserved most of its original characteristics: a Portuguese colonial town plan, a sixteenth-century fort and a number of old churches, as well as many of the eighteenth and nineteenth-century houses.

The first assessment of social organisation of the Indian Ocean humpback dolphin (Sousa plumbea) along the south coast of South Africa

2019 ◽  
Vol 97 (10) ◽  
pp. 855-865
Author(s):  
Thibaut Bouveroux ◽  
Stephen P. Kirkman ◽  
Danielle Conry ◽  
O. Alejandra Vargas-Fonseca ◽  
Pierre A. Pistorius
Keyword(s):  
South Africa ◽  
Indian Ocean ◽  
Group Size ◽  
Social Organisation ◽  
South Coast ◽  
The South ◽  
Mammal Species ◽  
Network Analyses ◽  
The Social ◽  
The Indian Ocean

The Indian Ocean humpback dolphin (Sousa plumbea (G. Cuvier, 1829)) is the most endangered marine mammal species in South Africa, and the overall decline of its abundance and group size may affect the social organisation of the species, potentially accentuating its vulnerability. Understanding the social organisation is therefore particularly relevant to conservation efforts. From photo-identification surveys along the south coast of South Africa from March 2014 to June 2015, we quantified association patterns and investigated the social organisation of Indian Ocean humpback dolphins using the half-weight index, social cluster, and network analyses. During the 101 surveys conducted and 553 h of survey effort, 98 sightings of dolphins were recorded and 65 individuals identified. Using individuals seen at least three times, this study reveals that the social network is well differentiated, as strong social divisions exist between individuals that seem to be split into four distinctive social clusters. Network strength was low; approximately half of the associations were low to moderate, whereas some individuals were strongly associated, especially between four pairs of individuals. Although this study is based on a limited number of individuals, our study nevertheless suggests that the atypical strong social bonds recorded here could result from behavioural responses following the decline in group size and abundance.

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