Northwest Monsoon Research Articles

On Investigating the Dynamical Factors Modulating Surface Chlorophyll-a Variability along the South Java Coast

Twelve years of remotely sensed all-sat merged chlorophyll-a concentration unveils strong signatures of chlorophyll-a blooms along the south Java coast. An unprecedented three-times increase in chlorophyll-a concentration is significantly observed along the south Java coast during the southeast monsoon (June–October) than the northwest monsoon (December–April). The multiple regression analysis of dynamic factors evidently indicates that seasonal upwelling is predominantly controlled by the seasonally evolving coastal eddies associated with the seasonally reversing south Java coastal currents (SJCC) and Ekman mass transport (EMT), followed by the relative roles of sea surface temperature (SST) and wind stress curl. The eddy-induced upwelling and EMT-induced coastal upwelling lead to chlorophyll-a blooms during southeast monsoon, well-supported by the entrainment of cold and saline waters (thermocline doming) with low spiciness. On the other hand, the coastal eddies associated with SJCC and SST anomalies play a significant role in modulating the interannual surface chlorophyll-a variability in the domain. Intense chlorophyll-a blooms are observed during the positive IOD years, whereas the least chlorophyll-a concentration is observed during the negative IOD years. The unprecedentedly least chlorophyll-a concentrations during 2010 and 2016 are attributed to the intense and prolonged surface marine heatwaves.

A clear north-to-south spatial gradience of chloride in marine aerosol in Chinese seas under the influence of East Asian Winter Monsoon

Particulate chloride is a major component of sea salt particles and plays a key role in atmospheric chemistry. Anthropogenic pollutants over the northeastern Asia can be transported to the adjacent seas through the northwest monsoon, which profoundly influences the chloride chemistry over the seas. In this study, spatial distribution of particulate chloride and its sources over the Chinese seas were investigated based on shipboard particle samplings especially online Single Particle Aerosol Mass Spectrometer (SPAMS) over Bohai Sea, North Yellow Sea, and South Yellow Sea (SYS) during a cruise in November 2012. A strong north-to-south (N-S) gradience in marine aerosol composition was found. The Cl−/Na+ ratios in PM2.5 and single particle composition by SPAMS indicated remarkable chloride enrichment in marine aerosol in the north (Bohai Sea), while depletion in southern SYS. The results of size distribution showed that particulate chloride had higher concentration in coarse particles, while the Cl−/Na+ ratio was much higher in submicron particles. In the north (38–40°N), biomass burning, carbonaceous, and Pb-rich type particles had high fractions in all chloride-containing particles identified by SPAMS (on average 66%). Combining chemical composition with back trajectory, it was found that fine-mode chloride enrichment in the north was mainly due to anthropogenic emission especially coal combustion and biomass burning from northern China. However, the high fine-mode chloride depletion in the south (32–34°N) was probably due to acid replacement by sulfate in aged aerosol during atmospheric transport. Our new findings reveal that marine aerosol in Chinese seas would show a clear N-S pattern of more fresh and anthropogenic enriched particles in the north, but more aged aerosol in the south during the East Asia Winter Monsoon, which provides new insights for the quantitative assessment of anthropogenic impact on marine aerosol and future modeling study.

Limnological environment with respect to conservation aspects of Patna Bird Sanctuary Jalesar, Etah (U.P.)

Patna Bird Sanctuary is located at Jalesar in the Etah district of U.P. It is spread in 108 hectares and has been declared as a Bird Sanctuay in 1991. Patna jheel is a typical rainfed wetland of Gangetic plain. It receives most of its water from north-west monsoon and some water from different nallas entering into jheel. Physico-chemical and biological characteristics of lake were studied during April 2013 to March 2014, to correlate the abundance of different flora and fauna. Study revealed richness in phosphate and nitrate. The main source of this richness in the lake has been traced out due to washing, bathing, agricultural activities and cultivation of trapa and growth of macrophytes. The jheel was marked with date trees (Phoenix sylvestrix) and harbors about 2, 00,000 birds belonging to over 200 different species. The border of jheel has been surrounded by Ipomea carnea tracts, serving good nesting ground for resident birds. Macrophytes comprising of submerged (Hydrilla verticillata, Ceratophyllum demersum, Vallisnaria spiralis, Potamogeton crispus and Najas), free floating (Salvinia, Azolla, Wolffia and Eichhornia) and rooted floated (Nymphoides cristata and N. indica). In some parts Ipomea aquatica were also observed.

Analysis of early Japanese meteorological data and historical weather documents to reconstruct the winter climate between the 1840s and the early 1850s

Abstract. The East Asian winter monsoon causes orographic snowfall over the windward side of the Japanese islands (facing the Sea of Japan and the northwesterly winter monsoon flow) and negative temperature anomalies around Japan. Daily weather information recorded in old Japanese diaries can provide useful information on the historical occurrences of snowfall days. Here, this information was combined with recently recovered early daily instrumental temperature data collected during the 19th century to reconstruct the occurrence of winter monsoon outbreak days (WMDs) from the 1840s to the early 1850s in Japan. Analyses of interannual and intra-seasonal variations in WMDs revealed active winter monsoon outbreaks in the early 1840s. In 1840/41 and 1841/42, these synchronously occurred with extreme snow events reported in central and southern China. However, winter monsoon outbreaks were absent during the middle to late winters of the mid-1840s and 1853/1854. Freezing records of Lake Suwa in central Japan showed that it did not freeze during 1844/1845 and 1853/1854, which was in agreement with our finding of inactive winter monsoons in these years. Comparing the occurrences of WMDs with early instrumental surface pressure data revealed that WMDs were associated with the active phases of the winter monsoon, as represented by an east–west surface pressure gradient over East Asia.

Hydrodynamic Conditions of the Banda and Northern Arafura Seas in the Northwest Monsoon (Februay2014)

The physical and hydrodynamic conditions in the Banda and Northern Arafura Seas (BAS) during northwest monsoon (February 2014) were investigated using a three-dimensional baroclinic nonlinear numerical model—the Hamburg Shelf Ocean Model (HAMSOM). This study found that northwesterly winds induced eastward surface currents that transported relatively fresh water from the Flores Sea to the Arafura Sea via the Banda Sea. It was also found that the westerly surface currents carried relatively cold water induced by upwelling along the northern coast of the Lesser Sunda Islands. Furthermore, the simulation results revealed that relatively saline surface water from the Indian Ocean intruding through the Ombai Strait and Timor Passage contributed to the surface water of the Eastern Banda Sea and Aru Basin being more saline than the surrounding water. Part of the surface water sank as a result of downwelling in the Arafura Sea. The BAS had higher salinity than the Makassar Strait at a depth of 75 –300m. The simulation results suggested that the higher salinity was due to the influence of the South Pacific Subtropical Water (SPSW) that entered the Indonesian Seas primarily through the Halmahera Sea.

Dynamic analysis of particulate pollution in haze in Harbin city, Northeast China

Abstract Based on the air quality data of Harbin in winter from 2015 to 2017, the national winter straw combustion data from 2016 to 2017 and the mixed single particle Lagrange comprehensive track model, Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT), dynamic analysis of Harbin’s winter air quality status and influencing factors. The air quality data were analyzed; it was found that the main pollutants in winter in Harbin were SO2, NO2, PM10 (particles with aerodynamic diameter ≤10 µm), and PM2.5 (particles with aerodynamic diameter ≤2.5 µm); the annual air pollution situation deteriorated sharply from November and continued until March of the following year. Through the research on straw fire prevention points in Harbin, the spatial pattern characteristics and causes of persistent haze in Harbin from 2015 to 2017 were dynamically analyzed. Combining the backward trajectory model to trace the source and trend of air mass in pollution, it is found that the air mass trend is consistent with the distribution of straw-burning points. The research results show that (1) during the winter from 2015 to 2017, the overall air quality situation in Harbin improved, the number of serious pollution days decreased year by year, and the main atmospheric pollutants were PM10 and PM2.5. In October and November, the pollution concentration peaked, and after December, the pollution concentration showed a downward trend until the next spring reached the valley and (2) the most obvious time of haze in Harbin is from November to December, and it is concluded that haze events are closely related to the large number of pollutants caused by the burning of straw around Harbin, and because the northwest monsoon climate affects the air quality, the transportation of fine particles caused by the burning of straw in winter in the surrounding areas of Harbin is the main cause of serious pollution in Harbin.

Pelagic tunicates (Appendicularia and Thaliacea) of Sri Lanka: two first records with an annotated checklist.

In broadening the understanding of the diversity, distribution and seasonality of gelatinous zooplankton of Sri Lanka, a survey ('Waya-jel-Survey) was carried out in coastal waters of the country from 2016 to 2020, and the collected specimens of pelagic tunicates were taxonomically identified. Further, a comprehensive literature survey was conducted and the previous records on the occurrences of pelagic tunicates within the exclusive economic zone of Sri Lanka were cross-checked and listed in developing the first-ever annotated checklist. Among the samples collected in this study, Pyrostremma spinosum and Thalia sibogae were reported for the first time from Sri Lankan waters while two more thaliaceans, i.e., Doliolum denticulatum and Pegea confoederata, and six appendicularians, i.e., Fritillaria borealis sargassi, F. formica digitata, Oikopleura cophocerca, O. fusiformis, O. longicauda, and O. rufescens were re-recorded. In total, forty species (including two subspecies) in 19 genera, belonging to five families from four orders of the classes Appendicularia (n = 17 species) and Thaliacea (n = 23 species) were reported to be inhabited in Sri Lankan waters. Most of the records were from the Laccadive Sea region while the majority of the species have been reported during the northwest monsoon (December to February) period.

Seasonal Variability of Waves Within the Indonesian Seas and Its Relation With the Monsoon Wind

The previous studies have simulated the variability of the wave within the Indonesian seas which showed that the variability of wave follows the seasonal pattern. However, their analysis only consider the influence of local wind forcings. The bias and error of their simulated wave were also unclear. In the present study, we investigate the variability of wave within the Indonesian seas and its relation with the surface wind speed using the combination of reanalysis and remote sensing data with high accuracies. We split the analysis into swell and wind wave to obtain the influence of local and remote wind forcings. We show that at the inner seas (i.e., the South China Sea, Java Sea, Flores Sea, Banda Sea and Arafura Sea), the variability of significant wave height (SWH) is majorly influenced by the variability of the speed of monsoon wind. The maximum SWH during Northwest monsoon (NWM) season is located at the South China Sea while during Southeast monsoon (SEM) season is at Arafura Sea. This indicates that the wind wave (sea) is dominant at the inner seas. At the open seas (i.e., Pacific Ocean and Indian Ocean) the variability of SWH less corresponds to the the speed of monsoon wind. The remote wind forcings control the wave variability in the open ocean area. This indicates that swell is dominant at the open seas. In general, the magnitude of SWHswell is also more than SWHsea within the Indonesian seas.

Provenance of Aeolian Sediments in the Ordos Deserts and Its Implication for Weathering, Sedimentary Processes

Identifying the provenance of aeolian deposits in semi-arid zones of China is beneficial in understanding Earth’s surface processes and helping to alleviate ecological stress. In this paper, we use grain-size, geochemical elements, heavy-minerals, and quartz grain morphology data to investigate the potential source of aeolian sands from the Ordos Deserts (Mu Us Sandy Land and Hobq Desert). Sedimentological, geochemical and geomorphological results indicate that significant provenance differences exist among various parts of the Mu Us Sandy Land, i.e., aeolian sediments from the southwest region are obviously distinct from other areas in the Mu Us Sandy Land but show the same external provenance with the Hobq Desert referring to the sorting, mineralogical maturity, geochemical characteristics, heavy-minerals, and quartz grain morphology. Comparing the samples from the Ordos Deserts with felsic rocks from potential sources via a serious of geochemical methods, we conclude that: 1) Aeolian sands from other regions of the Mu Us are a mixture of binary provenance, i.e., one originated from local lacustrine sediments and underlying sandstones, and another from the Alxa Plateau (AP) carried by northwesterly Asian winter monsoon. 2) The fluvial deposits denuded from the Qilian Orogenic Belt in the Northeastern Tibetan Plateau (NTP) and carried by the Yellow River are likely the initial material source for the southwest region of the Mu Us Sandy Land and the Hobq Desert. 3) The Yellow River plays a significant and critical role in sediment transport for sand seas in arid and semi-arid areas of northern China.

Natuna Off-Shelf Current (NOC) Vertical Variability and Its Relation to ENSO in the North Natuna Sea

During the northwest monsoon (NWM), southerly flow off the Natuna Islands appeared as the extension of the turning Vietnam coastal jet, known as Natuna off-shelf current (NOC). NOC is generated by the interaction of wind stress and the North Natuna Sea’s bottom topography. The purposes of the present study is to investigate the vertical variability of NOC and its relation to El Niňo Southern Oscillation (ENSO) using Marine Copernicus reanalysis data. The vertical variability refers to the spatial distribution of NOC pattern at the surface layer, thermocline layer, and deep/bottom layer. in 2014 as representative of normal ENSO condition. To investigate the effect of ENSO, the spatial distribution of NOC in 2011 and 2016 were compared which represent the La Niňa and El Niňo conditions, respectively. The results show that NOC starts to generate at the southeast monsoon season to the transition I season and peaks in the northwest monsoon season. The occurrence of NOC is identified at all depth layers with the weakened NOC at the deep layer. Related to the ENSO effect, La Niňa tends to strengthen NOC while El Niňo tends to weaken NOC. These are releted with the strengthening and weakening northerly wind speed during La Niňa and El Niňo, Respectively. During La Niňa events, the NOC occurs more frequently than during El Niňo. Thus, beside affecting the magnitude of NOC, ENSO also influence the frequency occurrence of NOC.

Spatial Distribution of Lift Net (bagan) and The Impact on Sardinella lemuru Catches in Senggrong Bay, Banyuwangi

The spatial distribution of lift net (bagan) and the impact on the Sardinella lemuru (lemuru) catches in Senggrong bay - Banyuwangi has been analysed. The data used in this study consists of Pleiades satellite data, aerial photographs of unmanned aerial vehicle (UAV) or drones and in situ measurements in the same period. Fishery data during 2013 to 2017 were analysed to determine the variability of Lemuru catches. The analysis of bagan spatial distribution was performed using visual interpretation technique. Spatial distribution of bagan was analyzed by overlaying data at different period. The results show that the number of bagan in Senggrong bay were 85 unit and spread evenly throughout the bay. In the northwest monsoon, the bagan were spreadedin the northern part of the bay, while in the southeast monsoon, the bagan were shifted to the south due to the high waves and wind speed. Lemuru spawning time was occured in May – July. During spawning time, the amount of Lemuru catches by bagan was relatively low. The peak of lemuru catch was occurred in the period of October to January. The impact of bagan on the decreasing of lemuru abundance is relatively low.

Northwest monsoon upwelling within the Indonesian seas

ABSTRACT The previous studies of upwelling within the Indonesian seas only focused on the Southeast Monsoon (SEM) season. The western coast of Sumatra Island; the southern coast of Java Island, Sunda Islands, and Sulawesi Island; the Banda Sea, the Maluku Sea, and the Arafura Sea are well-known SEM upwelling areas. However, the upwelling events during Northwest monsoon (NWM) have never been investigated. The investigation of NWM upwelling is challenging due to the broad cloud coverage, limiting the observation of infrared and visible sensors of the satellites. This study used the blended products of the satellite-based sea surface temperature (SST), chlorophyll-a (chl-a), sea level anomaly (SLA), surface wind, and rainfall to identify the NWM upwelling occurrences. Remote sensing reflectances 443 nm and 555 nm were also used to examine the influence of suspended sediment and organic matter which may bias the chl-a concentration. Along the northern coast of the Lesser Sunda Islands, the north coast of Papua Island and the Malacca Strait are the areas of NWM upwelling as denoted by the positive anomaly of chl-a, the negative anomaly of SST, and the negative anomaly of SLA. Focusing on the area along the northern coast of the Lesser Sunda Islands, the NWM upwelling is generated by offshore Ekman Mass Transport that reduces SST and increases chl-a. From 2010 onwards, El Niňo Southern Oscillation has a more consistent effect on the NWM upwelling than Indian Ocean Dipole. El Niňo (La Niňa) tends to weaken (strengthen) upwelling. The magnitude of NWM upwelling is weaker than SEM upwelling.

Ecological Roles of Benthic Community in Seafloor Northwards of Pulau Indah, Klang, Malaysia

Trait assessment is an alternative but effective method of biomonitoring benthic community in ecosystem, but it was rarely done in Malaysia. An assessment was done to identify the dominant sub-traits, or modalities, within benthic community in seafloor northwards of Pulau Indah, Klang, Malaysia, and to establish possible correlation between modalities with environmental parameters measured in the area. Sampling was conducted in November 2018, during Northwest Monsoon season. Sediments were obtained by using a Ponar Grab and filtered through 500 μm sieve. Sediments were subjected into Loss of Ignition method to extract organic carbon, and filtration method to determine particle size distribution percentages. 37 taxa were recorded in this study, totalling to 848 individuals. Traits assessment indicated vermiform body shape, direct larval development, deposit feeder, non-motile, asexual reproduction, and second-order opportunistic group as most dominant modalities in the study area. Station 1 recorded highest macrobenthos density (21000 ind./m2), while station 5 recorded highest diversity (H’=2.19). Functional diversity (FD) for reproduction method was highest in station 1 (FD=0.61), ecological group in station 4 (FD=0.73); body shape (FD=0.56) and larval development (FD=0.63) in station 5, and lastly, adult mobility (FD=0.70) and feeding mode (FD=0.66) in station 6. Principal component analysis showed Station 1 has most modalities attributed towards it. Pearson correlation analysis suggested particle size distribution as major connector for most modalities (P=0.05). As BTA study is still new in Malaysian waters, it could serve as a good starting point for future assessment related to ecological functioning of benthic community in Malaysian seafloor.

Seasonal variability of temperature, salinity, and surface currents at 0° latitude section of Indonesia seas

The Indonesian Seas are strongly influenced by the circulation system between the Pacific and the Indian Ocean, which play an important role in global circulation. In this study, an attempt is made to describe temperature, salinity, and water column stability using data obtained from the World Ocean Database (WOD), updated in 2018 at 0° latitude. The seasonal Temperature–Salinity (S-TS) were used to justify the water-mass types. The stability of the water column was analyzed based on the Brunt–Väisälä Frequency (N2). The transects were measured with depth up to 800 m and 200 km width, encompassing the Indian Ocean, Karimata Sea, Malaka Strait, Makassar Strait, Maluku Sea, Halmahera Sea, and the Pacific Ocean. Temperature and salinity profile revealed that the region in Indonesia’s eastern waters were found to have a deeper mixed layer depth (∼150 m) compared to the western waters of Indonesia (∼100 m). In the Pacific Ocean, the salinity layers were distinguishable compared to other layers. The T–S time diagram indicated the presence of six water-mass classes, including the water characteristic of the Pacific Ocean. It also shows that water mass from the Pacific Ocean more affects Indonesia seas in Southeast Monsoon. A relatively low salinity level distinguishes the water characteristics of the Karimata Strait compared to the other seas. In contrast, the Indian Ocean and Pacific Oceans, on the other hand, are more stable compared to other straits and seas along the equator transects (N2 up to 20 cycle/h). In the Northwest Monsoon, the temperature was higher compared to Southwest Monsoon. Analysis of meridional ocean currents showed a southward pattern except for Karimata Strait, which ranges from -1.5 to 1.5 m/s. The ocean currents condition found that the most energetic meridional current flows are in the Makassar Strait and affect the distribution of temperature, salinity, and stability of surface water.

Paleowind directions from the magnetic fabric of loess deposits in the western Chinese Loess Plateau and implications for dust provenance

AbstractThe aeolian loess-paleosol sequences in the Chinese Loess Plateau (CLP) are an excellent archive of variations in atmospheric circulation in the geological past. However, there is no consensus regarding the roles of the East Asian winter monsoon and westerly winds in transporting the dust responsible for loess deposition during glacial and interstadial periods. We conducted detailed measurements of the anisotropy of magnetic susceptibility (AMS) on two parallel loess profiles covering the most recent 130 ka in the western CLP to determine paleowind directions. Results show that the magnetic lineations of the loess and paleosol units in both sections are significantly clustered along the northwest to southeast direction. These observations demonstrate that the prevailing wind system responsible for dust transport in the western CLP was the northwesterly winter monsoon, rather than the westerly winds. The AMS-derived dust-bearing wind direction was relatively stable during the last glacial and interglacial cycle in the western CLP, consistent with sedimentary and AMS evidence from the eastern CLP. Accordingly, it is reasonable to conclude that large areas of deserts and Gobi deserts areas located in the upwind direction were the dominant sources for the aeolian deposits of the Loess Plateau.

Annual and seasonal precipitation trends and their attributions in the Qinling Mountains, a climate transitional zone in China

In this study, annual and seasonal precipitation trends and their connection with large-scale climate indices in the Qinling Mountains (QMs) were investigated using the innovative trend analysis (ITA), based on observed monthly precipitation data between 1959 and 2016 from 32 meteorological stations. The results indicated a declining trend in annual precipitation in the QMs. Seasonally, a decreasing trend was also observed in spring and autumn, while increasing trends were observed in summer and winter. Spring and autumn precipitations significantly contributed to this observed decline in annual precipitation. More importantly, both low and high values indicated a declining trend, which would have a significant influence on ecology and livelihood in the QMs. Additionally, the results of wavelet coherence showed that annual precipitation is strongly associated with the East Asian Summer Monsoon Index (EASMI), Southern Oscillation Index (SOI), South Asian Summer Monsoon Index (SASMI), South China Sea Summer Monsoon Index (SCSMI), and Southwest Australian Circulation Index (SWACI). However, its relationship with the North Atlantic Oscillation (NAO) and West African Summer Monsoon Index (WASMI) was insignificant, and seasonally, EASMI had negative effects on the precipitation in each season. It was also observed that spring and autumn precipitations were more sensitive to SOI than SWACI, while SASMI had a strong positive relationship with winter precipitation, and SCSMI was more negatively related to autumn and winter precipitation. This study will provide scientific basis for precipitation forecast, prevention, and mitigation of flood in the future.

Spatial and temporal variations in particulate organic carbon in Indonesian waters over two decades

Particulate organic carbon (POC) is one of the essential variables in oceanic biogeochemical processes. Assessing the spatiotemporal variability of POC will help deepen our understanding of the carbon cycle. In this study we collected moderate-resolution imaging spectroradiometer (MODIS) Aqua satellite data for surface POC in Indonesian waters during the period 2002–21, together with in situ data from the south-western Sumatran waters (SSW), Sunda Strait, Sumba–Savu waters and the Halmahera Sea and surrounds. These data were analysed to gain an understanding of the spatial and temporal variations in POC. Generally, high POC concentrations in Indonesian waters were found at coastal and continental shelves connected to the estuaries of large rivers; we assume that the POC concentrations in these areas are affected by terrestrial input. Meanwhile, in Indonesian waters apart from these estuaries, marine-derived materials are the main components of POC. The seasonal pattern of POC in Indonesian waters generally shows highest levels during the south-east monsoon and lowest levels during the north-west monsoon. Trends in POC concentrations are positively correlated with chlorophyll-a and negatively correlated with sea surface temperature. This study suggests that the combination of natural physicochemical processes and anthropogenic perturbations has significant effects on spatial and temporal variations in POC in Indonesian waters.

Variability of surface wind in Banda Sea and its correlation with El Niño and Southern Oscillation

Variability of surface winds in the Banda Sea and its correlation to El Nino and Southern Oscillation (ENSO) have been clearly demonstrated using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis data. Surface winds in the Banda Sea are affected by monsoons. When the northwest monsoon, the wind comes from the north and west to the southeast, while the southeast monsoon, the wind comes from the southeast to the northwest. ENSO changes the direction and speed of the wind during the west season, whereas it only changes the speed during the east season.

Wave Energy Potential for Development of Renewable Energy in Riau Archipelago Province

Energy and electricity demand in Riau Islands is increasing rapidly due to the fast-growing population, urbanization, industrial development, and economic growth. The limitations of energy and electricity in the Riau Islands caused frequent blackouts. To support the high demand for energy and electricity in the Riau Islands, renewable energy is the most suitable alternative energy solution. Renewable energy is not only playing a key role in providing energy but also providing long-term clean and sustainable energy. We investigated the wave energy potential in the Riau Islands Sea in four different consecutive monsoons (North monsoon, East monsoon, South Monsoon and West Monsoon) using ECMWF data during January 2018 to December 2018 with 0.125o x 0.125o and 6 hourly spatial and temporal resolutions. We extracted bathymetry data from NOAA’s database ETOPO1 and forecasting wave characteristics use the SPM (Shore Protection Manual) method. The potential wave energy simulation from significant wave height (Hs) and energy period (Te) was shown in spatial distribution based on different monsoon. Our studies found that the potential wave energy was higher in north monsoon with maximum spatial of wave power density 3.240 – 3.640 kW.m-1. The east monsoon tended to be lower potential wave energy with dominance of wave power density at 0 – 0.127 kW.m-1. Keywords: wave power density, potential wave energy, ECWFM, monsoon

Transport of floating litter within Manila Bay, Philippines

The increasing amount of marine litter is a global issue that is also being experienced within the Manila Bay Philippines. To better understand the behavior of litter within the bay, particle tracking simulations of floating litter released from several sources were conducted. Forward-in-time (PTM-FIT) simulation of particle movements showed that during the southwest monsoon season, litter particles released by river sources tend to accumulate toward five hotspots located along the northeastern coastline of the bay. Backward-in-time (PTM-BIT) simulation of particles released from the identified hotspots showed coastal and foreign sources contributing to the litter collected within these areas. PTM-FIT simulations during the southwest monsoon season showed that particles tend to circulate locally within the bay before being transported toward the hotspots. By contrast, PTM-FIT simulations during the northwest monsoon season showed that litter particles tend to travel toward the mouth of the bay, an implication for global marine litter pollution.