Satellite Derived Measurements of Coastal Water Chlorophyll-a Variability (original) (raw)
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Variability of Chlorophyll-a Distribution Off Pahang Coastal Waters Using Satellite Images
malaysiageospatialforum.org
Determination of chlorophyll-a (Chl-a) distribution in the coastal waters is important to understand the physical conditions of the area. This study was conducted to understand the spatial and temporal dynamic of Chl-a in the coastal waters off Pahang, Malaysia and to determine factors influencing its variability. Five years of Aqua MODIS satellite data from January 2006 to December 2010 of Chl-a distribution and sea surface temperature (SST) were analysed. Daily Level 1A data (1 km spatial resolution) were processed to monthly composites Level 3 data using SeaDAS and ERDAS Imagine software. Variability of the time series of monthly Chl-a and SST images were determined using Empirical Orthogonal Function (EOF) analysis. Four modes explained the variability for Chl-a distribution and SST in this region with total variance of 83.63 % and 97.49 % respectively. First mode for the distribution of Chl-a (76.0 % of variance) explained the seasonal cycle. Mode 2 (4.18 % of variance) showed high distribution of Chl-a off Sg. Pahang river mouth and along the coast during the Southwest and Northeast monsoon respectively. Mode 3 (2.08 % of variance) indicated distribution of Chl-a along the coast which explained the Northeast monsoon and subsequently mode 4 (1.37 % of variance) indicated the inter-monsoon periods at the river mouth and along the coast. Meanwhile EOF variance for SST showed that the first mode (97.0 % of variance) explained the seasonal cycle. Mode 2 (0.18 % of variance) indicated the inter-monsoon periods indicating variability along coast towards offshore. Mode 3 (0.17 % of variance) and Mode 4 (0.14 % of variance) explained the variability during the Northeast monsoon (along coast and offshore) and Southwest monsoon (offshore and south of river mouth) respectively. This study showed that the Chla distribution off Pahang coastal water region was influenced by SST and wind stress direction during monsoons period.
MODIS satellite data for modeling chlorophyll-a concentration in Malaysian coastal waters
2010
This study is compared among four algorithms for mapping chlorophyll-a spatial variations from MODIS satellite data along the east coast of Malaysia. These algorithms are:(i) Aiken's,(ii) Clark-3-bands,(iii) Gordon and (iv) Normalized Difference Chlorophyll Index (NDCI) algorithm. The results show that the Aiken's algorithm is appropriate for accurately synoptic chlorophyll mapping distribution. In fact, the algorithm performs the lowest root mean square error of±0.10 mg/m3 as compared to other algorithms.
Malaysian applied biology, 2017
Chlorophyll-a concentration is one of the major indicators of phytoplankton production in the ocean. Identification of chlorophyll-a distribution and productivity is important to understand physical and biological processes in the ocean. The objectives of this study are to determine the spatial and temporal distribution of chlorophyll-a and to identify influence of sea surface temperature (SST) and current on chlorophyll-a concentration variation in the Exclusive Economic Zone (EEZ) waters of Peninsular Malaysia. Satellite data of chlorophyll-a concentration and SST (2007 to 2014) were derived from MODISAqua and geostrophic current was obtained from NOAA Ocean Watch. Empirical Orthogonal Function (EOF) analysis was used to determine the spatial and temporal variation of chlorophyll-a. Five modes represented the variation of chlorophyll-a. Mode 1 (60.62%) explained seasonal pattern, Mode 2 (27.83%) indicated patterns during the southwest monsoon, Mode 3 (19.96%) highlighted the inter...
Nine years of monthly data of MODIS derived chl-a around Makassar Strait of Indonesia were used to investigate the spatial and temporal variability of chl-a concentration. The variability was further analyzed by empirical orthogonal function (EOF). The first mode (62.08% of variance) showed variability of seasonal pattern. The second mode (5.75% of variance) showed variability during the Northwest monsoon and the Southeast monsoon. Meanwhile, the third mode (2.72% of variance) and the fourth mode (2.25% of variance) showed variability during the Transition monsoon I and II, respectively.The variability of chl-a along the Borneo Island is influenced by river runoff during the Northwest monsoon, while the variability of chl-a along the Sulawesi Island is induced by strong wind and current during the Southeast monsoon.
Journal of Oceanography
Seasonal and interannual variations of chlorophyll-a (chl-a) in the upper Gulf of Thailand (uGoT) were obtained using new regionally tuned algorithms applied to Moderate Resolution Imaging Spectroradiometer-Aqua. This long time-series (2003–2017) data were analyzed in the context of variations in environmental conditions associated with the Southeast Asian Monsoon. Chl-a distribution patterns were distinct for the non-monsoon (NOM), southwest-monsoon (SWM), and northeast-monsoon (NEM) seasons. During the SWM/NEM, high/low chl-a concentrations were associated with high/low precipitation and river discharge. During the NOM chl-a concentrations were generally low, because of low precipitation. In general, chl-a variability was tightly coupled to discharge from the Chao Phraya and Tha Chin rivers. Chl-a concentrations were generally higher in the north, but chl-a accumulation in the east/west of the uGoT could be linked to piling of freshwater to the east/west during the SWM/NEM caused ...
Journal of Ecological Engineering
The chlorophyll-a (chl) abundances on the Fisheries Management Area of Indonesia Republic (WPP-RI 572), as fishery resources over the western coast of Sumatera (WSC) and Sunda Strait, were examined in this study. The extensive investigation on the mechanism ocean dynamics on chl variability along WSC was observed by using remotely sensed data on the surface. The spatial analysis was conducted using the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Ocean colour data for a period of January 2003 to December 2015. On seasonal time scale, the surface chlorophyll-a (schl) concentration in the southern tip of Sumatra is higher than the schl in the northern tip of Sumatra. The obtained results showed that the schl concentration in the southern tip of Sumatra increases (decreases) during the southeast (northwest) monsoons. Interestingly, its interactions with the southeast monsoon wind result in intensified coastal upwelling along the monsoon trough in July-August. It triggered a large bloom of the schl concentration from the upwelling region of southern tip Sumatra. Moreover, the schl in the center region followed the peak of the equatorial wind during the period transition in the Indian Ocean which is controlling the dynamics ocean such as upwelling event. Meanwhile, the opposite situation of the schl concentration observed low along the western coast of Sumatra during the northwest monsoon. At the same time, strong upwelling observed at the northern tip of Sumatra was associated with intense cooling on the sea surface temperature. It triggered a large bloom of high schl water from the upwelling region of northern Sumatra Island.
Environmental Monitoring …, 2012
A study was conducted to investigate the influence of Asian monsoon on chlorophyll-a (Chl-a) content in Sabah waters and to identify the related oceanographic conditions that caused phytoplankton blooms at the eastern and western coasts of Sabah, Malaysia. A series of remote sensing measurements including surface Chl-a, sea surface temperature, sea surface height anomaly, wind speed, wind stress curl, and Ekman pumping were analyzed to study the oceanographic conditions that lead to large-scale nutrients enrichment in the surface layer. The results showed that the Chl-a content increased at the northwest coast from December to April due to strong northeasterly wind and coastal upwelling in Kota Kinabalu water. The southwest coast (Labuan water) maintained high concentrations throughout the year due to the effect of Padas River discharge during the rainy season and the changing direction of Baram River plume during the northeast monsoon (NEM). However, with the continuous supply of nutrients from the upwelling area, the high Chl-a batches were maintained at the offshore water off Labuan for a longer time during NEM. On the other side, the northeast coast illustrated a high Chl-a in Sandakan water during NEM, whereas the northern tip off Kudat did not show a pronounced change throughout the year. The southeast coast (Tawau water) was highly influenced by the direction of the surface water transport between the Sulu and Sulawesi Seas and the prevailing surface currents. The study demonstrates the presence of seasonal phytoplankton blooms in Sabah waters which will aid in forecasting the possible biological response and could further assist in marine resource managements.
Oceanological and Hydrobiological Studies, 2020
Chlorophyll-a (Chl-a) concentration is an important issue in ocean ecosystem management and research. This study investigates seasonal and annual variability in Chl-a and its relationship with sea surface temperature (SST) and river discharge in the shelf region of the Northern Bay of Bengal (BoB), as well as validates satellite data against in-situ data. Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua satellite data on Chl-a concentration and SST from 2002–2018 were used in this study. River discharge data were obtained from the Bangladesh Water Development Board (BWDB). The annual Chl-a concentration ranged from 2.08 to 2.94 mg m−3, with an average of 2.43 ± 0.24 mg m−3. The Chl-a concentration was found higher (2.21 ± 0.56 mg m−3) during the northeast monsoon (October–February) and lower (1.81 ± 1.14 mg m−3) during the pre-monsoon season (March–May). The study revealed a declining trend in Chl-a concentration from 2002 to 2018, and the rate of change was −0.0183 mg m−3...
Remote Sensing, 2021
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 ...
Spatial and temporal variability of surface chlorophyll-a in the Gulf of Tomini, Sulawesi, Indonesia
Biodiversitas Journal of Biological Diversity
Sari QW, Siswanto E, Setiabudidaya D, Yustian I, Iskandar I. 2018. Spatial and temporal variability of surface chlorophyll-a in the Gulf of Tomini, Sulawesi, Indonesia. Biodiversitas 19: 793-801. The Gulf of Tomini (GoT) is mostly influenced by seasonal and interannual events. So, the immensive aim of this study is to explore spatial and temporal variations of chlorophyll-a (chl-a) and oceanographic parameters in the GoT under the influences of monsoonal winds, El Niño Southern Oscillation (ENSO), and Indian Ocean Dipole (IOD). The data were collected from the satellite imaging of chl-a and sea and surface temperature (SST) as well as surface wind from the reanalysis data for a period of January 2003 to December 2015. Monthly variations of the chl-a and SST in the GoT reveal chl-a bloom in the center part to the mouth of the GoT during the southeast monsoon season (boreal summer). The chl-a concentrations were relatively higher (>0.1 mg m-3) and distributed throughout most of the...