The Leeuwin current

The Leeuwin Current (LC) is a warm, poleward flowing ocean boundary current off the west and south coasts of Australia, driven by large-scale meridional (north-south) pressure gradient. On the interannual time scale, the strength of the LC is influenced by ENSO-related thermocline anomalies, and transmitted from the equatorial western Pacific into the southeast Indian Ocean through the Indonesian Archipelago. The LC and its interannual variability have profound impacts on marine ecosystems off the west and south coasts of Australia. For example, high recruitment of the western rock lobster (Panulirus cygnus) fishery of Western Australia is influenced by a stronger LC and the associated warmer water temperatures. Over the period from mid-1970s to mid-1990s, a trend of shallowing thermocline (subsurface cooling) in the equatorial western Pacific, which is coupled with a weakening trend of the trade winds in the Pacific, has transmitted into the southeast Indian Ocean and the LC region and caused a multi-decadal weakening trend of the LC. Comparing climate models and forced ocean circulation models suggests that the weakening LC is likely due to a combined effect of both global warming and natural variability in the climate system. There have been persistent warming trends observed in the LC and on the shelf in waters off the west coast during the past five decades. Over the same time period, more frequent Indian Ocean Dipole events and an upward trend of the Southern Annual Mode may have reduced the strength of the westerly winds and storm activity off the southwest coast, which may have adjusted the air-sea heat flux in the LC region and overcome the reduction of the LC heat transport to cause the warming trend. Both the changes in the LC and the air-sea freshwater flux may have also caused the observed increase in surface salinity off the coast. The surface warming and subsurface cooling, in combination with the reduction of storm activity, may have increased the vertical stratification in the water column and reduced vertical mixing in the LC region. Climate model simulations suggest that reductions of trade winds in the tropical Pacific, increase in the frequency of Indian Ocean Dipole events, and the upward trend of Southern Annual Mode in recent decades are mostly due to the effect of the increased Feng et al. 2009 www.oceanclimatechange.org.au 2 greenhouse gases in the atmosphere. Climate model projections suggest these climate trends will likely continue in the future, so that the LC could continue to weaken slowly

Studies of Tiros and Nimbus radiometric observations Final report

Data analyses of Tiros and Nimbus radiometric observation

Analysis of Flood Discharge due to Impact of Tropical Cyclone

Tropical Cyclone Seroja, which occurred between April 2 to 6, 2021, is one of the strongest storms ever in East Nusa Tenggara. The track results of the cyclone showed that Seroja, formed at coordinates 10.5° S and 123° E, moved towards west longitude to Sumba Island and continued towards Australia. Moreover, the Global Precipitation Measurement (GPM) output was used to analyze the rainfall conditions at the center of the Seroja cyclone through the Kambaniru watershed in East Sumba, and the results showed that the precipitation continued to increase during Seroja's development to reach 225 mm. Therefore, this study aimed to analyze the effect of the rainfall during the storm on the maximum runoff experienced in the Kambaniru watershed through the application of quantitative analysis on the rainfall data from GPM data. The process involved analyzing the flood discharge using the HSS-SCS Curve Number method and GPM data, which were initially used to evaluate the rainfall during the TC Seroja due to limited field data. The results showed that the CN value in the Kambaniru watershed was in the AMC III condition with a curve number of 88.90 and the maximum flood during the Seroja storm was recorded to be 2,987 m3/s which is higher than the flood discharge for the 500 year return period. It was also discovered that the narrowing of the river channel on the Kambaniru Bridge section contributed to the collapse of the bridge. Doi: 10.28991/CEJ-2022-08-09-01 Full Text: PD

Hydrodynamics across seagrass meadows and its impacts on Indonesian coastal ecosystems: A review

Seagrass canopies are important components of the world’s coastal environments providing critical ecological services. Nearshore hydrodynamics, i.e., waves and currents, are essential in controlling the ecological processes across coastal environments. Seagrass meadows can impose more complex hydrodynamics processes by attenuating sea-swell waves and decreasing the impact of nearshore mean water level rise due to wave setup and Infragravity (IG) waves. Consequently, the seagrasses dissipate waves and reduce flows allowing sediments to settle and accrete the shorelines. However, despite their significant roles, knowledge of hydrodynamics in the Indonesian seagrass ecosystems is relatively limited compared to other coastal ecosystems such as sandy beaches, mangroves, and coral reefs. This review highlights the dynamics of waves and currents, and their interaction with sediment transport and ecological processes, including biogeochemical and dispersal processes on the seagrass ecosystem contributing to the existing seagrass research in Indonesia. The associated literature is collected from scientific databases such as Scopus and Google Scholar that range between 1965 and 2021. The result showed that most of the research on hydrodynamic in seagrass ecosystems was carried out in temperate zones. Until recently, there have been limited publications discussing the interaction between the Indonesian (tropical) seagrass ecosystem and hydrodynamics parameters, even though the region has abundant seagrass species. Moreover, Indonesia is strongly influenced by various atmospheric-oceanic forcing, including the Asian monsoon affecting the dynamic of the coastal area with seagrass ecosystems. At a canopy scale, the correlation between the nearshore (tropical) hydrodynamics and ecological processes in the system is yet to be explored. Considering the potential benefit of seagrasses to coastal ecosystems, developing future research in hydrodynamics across the ecosystem is critical to overcoming the knowledge gaps in Indonesia. The knowledge gained could support the Indonesian seagrass ecosystem services and their resilience to potential hazards and climate change

Atlas of Ocean Wealth

The Atlas of Ocean Wealth is the largest collection to date of information about the economic, social and cultural values of coastal and marine habitats from all over the world. It is a synthesis of innovative science, led by The Nature Conservancy (TNC), with many partners around the world. Through these efforts, they've gathered vast new datasets from both traditional and less likely sources.The work includes more than 35 novel and critically important maps that show how nature's value to people varies widely from place to place. They also illustrate nature's potential. These maps show that one can accurately quantify the value of marine resources. Further, by enumerating such values, one can encourage their protection or enhancement for the benefit of people all around the world. In summary, it clearly articulates not just that we need nature, but how much we need it, and where

Tropical coastal engineering in Indonesia adapting to near-term ocean-climate changes

Bali Coastal Experimental Station, Public Works of ROI is seeking Tropical Coastal Engineering (TCE)\ud in Indonesia. As a near-term perspective of ocean climate changes in the western tropical Pacific, there are three major\ud effects concerning to TCE. One is the decadal oscillation of North Pacific Ocean (PDO) that is related to long-term\ud changes in ENSO, such as La Nina dominant and El Nino dominant periods. Based on multivariate ENSO index (MEI),\ud it is indicated that El Nino dominant period may shift to La Nina dominant around 2007 that will increase rainfall in the\ud Indonesian archipelago. The second one is lunar nodal tide of 18.6 year period. In 2007, an extreme flood modulated by\ud coastal tide occurred in Jakarta and some coastline cities in Indonesia. Its next peak is expected in 2025. Heavy rainfalls\ud caused by El Nino dominant period and the peak of lunar nodal tide may cause the estuary flooding in the next 25 years.\ud The third effect is the changes in solar activities. Observations of "Sunrise", a solar observation satellite in January 2012,\ud found that the solar magnetic field becomes "quadrupole structure" that may reduce solar energy and increase of\ud galaxlian cosmic ray resulting in increase of cloud cover especially in the Inter-Tropical Convergence Zone (ITCZ).\ud This effect could trigger a mini-Ice Age on Earth with increasing of precipitation in the tropical area. An increase of\ud flooding may cause the increase of sediment transport from the river. TCE should solve these challenges of coastal and\ud estuary problems in Indonesia. This paper summarizes these effects in Indonesian costs and perspectives of TCE

RAMA : the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction

Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 90 (2009):459-480, doi:10.1175/2008BAMS2608.1.The Indian Ocean is unique among the three tropical ocean basins in that it is blocked at 25°N by the Asian landmass. Seasonal heating and cooling of the land sets the stage for dramatic monsoon wind reversals, strong ocean–atmosphere interactions, and intense seasonal rains over the Indian subcontinent, Southeast Asia, East Africa, and Australia. Recurrence of these monsoon rains is critical to agricultural production that supports a third of the world's population. The Indian Ocean also remotely influences the evolution of El Niño–Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), North American weather, and hurricane activity. Despite its importance in the regional and global climate system though, the Indian Ocean is the most poorly observed and least well understood of the three tropical oceans. This article describes the Research Moored Array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA), a new observational network designed to address outstanding scientific questions related to Indian Ocean variability and the monsoons. RAMA is a multinationally supported element of the Indian Ocean Observing System (IndOOS), a combination of complementary satellite and in situ measurement platforms for climate research and forecasting. The article discusses the scientific rationale, design criteria, and implementation of the array. Initial RAMA data are presented to illustrate how they contribute to improved documentation and understanding of phenomena in the region. Applications of the data for societal benefit are also described

The Indonesian Throughflow Circulation Under Solar Geoengineering

The Indonesia Throughflow (ITF) is the only low-latitude channel between the Pacific and Indian oceans, and its variability has important effects on global climate and biogeochemical cycles. Climate models consistently predict a decline in ITF transport under global warming, but it has not yet been examined under solar geoengineering scenarios. We use standard parameterized methods for estimating ITF: the Amended Island Rule and Buoyancy Forcing, to investigate ITF under the SSP2-4.5 and SSP5-8.5 greenhouse gas scenarios, and the geoengineering experiments G6solar and G6sulfur that reduce net global mean radiative forcing from SSP5-8.5 levels to SSP2-4.5 levels using solar diming and sulfate aerosol injection strategies. Six model ensemble mean projections for 2080&ndash;2100 relative to historical ITF are reductions of 19 % under the G6solar scenario and 28 % under the G6sulfur scenario which compare with reductions of 23 % and 27 % under SSP2-4.5 and SSP5-8.5. Thus, significant weakening of the ITF occurs under all scenarios, but G6solar closer approximates SSP2-4.5 than does G6sulfur. In contrast with the other three scenarios which show only reductions in forcing due to ocean upwelling, the G6sulfur experiment shows a large reduction in ocean surface wind stress forcing accounting for 47 % (38 %~65 % across model range) of the decline of total ITF transport. There are also reductions in deep-sea upwelling in extratropical western boundary currents.</p