Distribution Of Chlorophyll-a Concentration Research Articles

Distribution of chlorophyll-a concentration with the catch of julung fish in Ternate Island city

The study was conducted during March-May 2017 in the Coastal Waters of Ternate Island of North Maluku Province with the aim to study the relationship between the concentration of chlorophyll-a and the catch of Hemiramphus sp and its potential fishing area. Using experimental fishing method and non-linear regeneration analysis and GIS analysis. The result of this research shows that oceanographic factor that is chlorophyll-a concentration has significant effect on the catch of julung fish with correlation coefficient value of 0.729, with potential catch area located at three locations ie at coastal of Ngade to Kalumata on location 00o45'00"N - 127o21'03"E to 00o45'28.924"N - 127o22'08.893"E, coastal Keluarah Fitu at the location 00o44'39.490"N -127o19'51.083"E to 00o45'09.150"N - 127o20'52.263"E, and on the coast of Kelurahan Rua on location 00o45'51.169"N - 127o17'25.857"E to 00o46'42.457"N - 127o17'45.633"E.

Evaluating the impact of sea surface temperature (SST) on spatial distribution of chlorophyll-a concentration in the East China Sea

In this study, we analyze spatial and temporal sea surface temperature (SST) and chlorophylla (Chl-a) concentration in the East China Sea (ECS) during the period 2003–2016. Level 3 (4 km) monthly SST and Chl-a data from the Moderate Resolution Imaging Spectroradiometer Satellite (MODIS-Aqua) were reconstructed using the data interpolation empirical orthogonal function (DINEOF) method and used to evaluated the relationship between the two variables. The approaches employed included correlation analysis, regression analysis, and so forth. Our results show that certain strong oceanic SSTs affect Chl-a concentration, with particularly high correlation seen in the coastal area of Jiangsu and Zhejiang provinces. The mean temperature of the high correlated region was 18.67 °C. This finding may suggest that the SST has an important impact on the spatial distribution of Chl-a concentration in the ECS.

Variability Chlorophyll-a And Sea Surface Temperature As The Fishing Ground Basis Of Mackerel Fish In The Arafura Sea

Arafura Sea is one of the waters in the eastern region of Indonesia that is rich in marine and fisheries potentials because of its fertile conditions which is suitable for fishing ground. One of the fish resources which have important economic value at the Arafura Sea is big pelagic fish such as Mackerel. Thus this study aims to determine the spatial and temporal distribution of Mackerel in the Arafura Sea based on fishing boat coordinate data, to know the distribution of chlorophyll-a concentration and SST from MODIS satellite data in the Arafura Sea and to determine the correlation of chlorophyll-a and SST to the Mackerel catch distribution. This study was conducted in December 2016 until February 2017 in the Arafura Sea, image data analysis of MODIS level-3 conducted at the Laboratory of Oceanography FPIK UNDIP. The data used are Mackerel catch data, the Chlorophyll-a data and SST from MODIS satellite from June to August 2015. The results of this study showed that the distribution of Mackerel catch from June to August more were caught in August a total of 62.2 tons for 19 trips. While the chlorophyll-a between June and August ranged from 0.30 to 8.04 mg/m3 and SST in June-August ranged from 24.6 °C - 28.4 °C. The correlation between chlorophyll-a and Mackerel catch results showed very strong correlation (correlation coefficient (r) 0.934). While the correlation between SST with the Mackerel catch showed a strong correlation (correlation coefficient (r) 0.664).

Identifying Distribution of Chlorophyll-a Concentration Using Landsat 8 OLI on Marine Waters Area of Cirebon

Phytoplankton is a microscopic plant that has a function to produces oxygen and organic substances. It also plays a role as a main producer in the food chain of a marine ecosystem. Chlorophyll-a is a colour pigment most common in phytoplankton species, so that the concentration level of chlorophyll-a can be used as an indicator of the abundance of phytoplankton cells, and as a reference for predicting organic potency in the aquatic area. This research discusses about the spatial and temporal distribution of chlorophyll-a and its correlation with salinity and total suspended solid (TSS), in the seawaters of Cirebon, West Java. The goal of this research is to be a source of information for fishermen, and other stakeholders whose related subjects in the field of marine and fisheries to predict fertile water regions and can also be used as an indicator in discovering potential areas to catch pelagic fish in Cirebon seawaters. Chlorophyll-a concentration, salinity, and TSS are identified using remote sensing data such as Landsat-8 OLI multi temporal images according to dry and wet month parameters in the 2014-2015. The results of the processed image are then validated between in-situ measurements in the field and remote sensing imagery at the same time. This research utilizes descriptive analysis, and statistics with spatial approach. The results of the research show that temporally, chlorophyll-a levels have a tendency to be higher in wet months compared to dry months, while chlorophyll-a is higher in areas near the coastline compared to open sea areas. The distribution of chlorophyll-a concentration is affected by salinity and TSS distribution, where salinity has the negative relationship and TSS has the positive relationship with chlorophyll-a distribution.

Pengaruh Sebaran Konsentrasi Klorofil-a Berdasarkan Citra Satelit terhadap Hasil Tangkapan Ikan Tongkol (Euthynnus sp) Di Perairan Selat Bali

One of fisheries potential in Bali Strait is tuna fish (Euthynnus sp). Tuna fish (Euthynnus sp) resources is highly influenced by waters productivity which indicated by the chlorophyll-a concentration distribution. The aims of this study are: to find out the concentration spatial of chlorophyll-a distribution in Bali strait, to find out temporal variability of chlorophyll-a and tuna fish (Euthynnus sp) in Bali strait, and to find out the influence of chlorophyll-a concentration distribution to the catch of tuna fish (Euthynnus sp) in Bali strait. The analysis of the influence of chlorophyll-a concentration distribution to the catch of tuna fish (Euthynnus sp) in Bali strait uses regression polynomial order 2, correlation, and cross correlation. The influence of chlorophyll-a concentration distribution to the catch of tuna fish (Euthynnus sp) in Bali strait yearly time series climatology amounted to R2 = 0,1624 or 16,24%, the correlation coefficient values obtained by r = 0,1889. Seasonal time series climatology in west season (December - February) R2 = 0,0707 or 7,07%, the correlation coefficient values obtained by r = 0,0749. The transitional season 1 (March - May) R2 = 0,0095 or 0,95%, the correlation coefficient values obtained by r = - 0,0092. The east season (June - August) R2 = 0,086 or 8,6%, the correlation coefficient values obtained by r = - 0,2155. The transitional season 2 (September - November) R2 = 0,0482 or 4,82%. The correlation coefficient values obtained by r = - 0,1805

CHLOROPHYLL-A SPREAD ANALYSIS USING MERIS AND AQUA MODIS SATTELLITE IMAGERY (Case Study: Coastal Waters of Banyuwangi)

Indonesian is the archipelago country, 2/3 of the total area of Indonesia is the ocean. Oceans become a source of life for Indonesia people, including in the region of Banyuwangi. The potential of marine products in Banyuwangi regency not only fish, but also there are squid, crab, shellfish and others. Existence of fish can not be separated from the marine ecosystem, especially the food producers who are in the sea, the chlorophyll-a in phytoplankton. Information used to obtain the distribution of chlorophyll-a concentration value can be obtained from the data processing Aqua MODIS and Envisat Meris satellite imagery; which is reinforced by in situ data in the form of sea water sampling tested in the laboratory. Image processing using algorithms ATBD-19 for the Aqua MODIS imagery and algorithms Case-2 Water Processor (C2WP) for Envisat MERIS imagery. From this research, obtained a map of the distribution of chlorophyll-a concentrations in coastal waters of Banyuwangi generated from satellite image processing and analysis of several in situ data, based on the parameters of chlorophyll-a concentration. These results can be concluded that Aqua MODIS has a strong enough correlation to data in situ, with a correlation coefficient of r2 amount 0.5495. While the correlation between data in situ with Envisat MERIS imagery is quite weak with r2value amount 0.3782.

桑沟湾春季叶绿素a浓度分布及其影响因素

桑沟湾春季叶绿素a浓度分布及其影响因素

Bathymetrical influences on spatial and temporal characteristics of chlorophyll-a concentrations in the Southern Ocean from 2002 to 2012 (October to March) using MODIS

Phytoplankton blooms, particularly in the Southern Ocean, can have significant impact on global biogeochemistry cycling. To investigate the accuracy of chlorophyll-a distribution, and to better understand the spatial and temporal dynamics of phytoplankton biomass, we examine chlorophyll-a estimates (October–March from 2002 to 2012) derived from Moderate Resolution Imaging Spectrometer (MODIS) data following the ocean chlorophyll-a 3 model (OC3M) algorithm. Noticeable seasonality occurs in the temporal distribution of chlorophyll-a concentrations, which shows the highest value in December and January and an increasing tendency during the 2002–2012 period. The spatial distribution of chlorophyll-a varies greatly with latitude, as higher latitudes experience more phytoplankton blooms (chlorophyll-a concentration larger than 1 mg/m3) and marginal seas (Ross Sea and Amundsen Sea) show different bloom anomalies caused by two dominant algae species. Areas at higher latitudes and shallow water (<500 m) experience the shorter ice-free periods with greater seasonality. A noticeable bathymetry gradient exists at 2500-m isobaths, while water at the 500–2500-m depth experiences quite long ice-free periods with a stable water environment. Blooms generally occur near topographic features where currents have strong interactions when the water depth is more than 2500 m. Based on these findings, we can classify the Southern Ocean into two bloom subregions, 0–500 m as an enhanced bloom zone (EBZ), and 500–2500 m as a moderate bloom zone (MBZ). The EBZ has a quite high-bloom probability of about 30%, while the MBZ has only 10%.

Características termohalinas de las aguas costeras del Caribe sur de Costa Rica

In August and November 2012, two hydrographic surveys were conducted in the coastal region of the Southern Caribbean of Costa Rica, between the Port of Limon and Gandoca Lagoon. A CTD (conductivity, temperature and depth profiler) was used at 43 stations to determine temperature, salinity and chlorophyll-a. It was determined that spatial and temporary variations of surface temperature were small, with values ranging between 28.6°C and 30°C. In addition, surface salinity ranged between 33.3 and 35.2 PSU and the average spatial distribution of chlorophyll-a concentration in surface waters was 0.64 mg m-3, with maximum and minimum values of 1.1 mg m-3 and 0.19 mg m-3, respectively. The vertical temperature field was characterized by a warm mixed layer (T ~ 29°C), which extended to 60 m deep in November and less than 10 m deep in August. During the two sampled months, from the vertical structure of the isotherms, we found a cyclonic motion (from the surface to 15 m deep) in the region adjacent to Cahuita, and an anticyclonic motion at 20 m in August and 40 m in November. We identified water masses present in the water column to the depths sampled: CSW, 0-80 m and SSW, > 80 m.

Sensitivity analysis on Lake Taihu data assimilation scheme of chlorophyll-a concentration

太湖叶绿素a同化系统对于不同参数的敏感性将直接影响到该系统能否精确的估算太湖叶绿素a的浓度分布.利用2009年4月21日环境一号卫星(HJ-1B CCD2)影像数据反演太湖叶绿素a浓度场信息.以此作为背景场信息,结合基于集合均方根滤波的太湖叶绿素a同化系统,分析和评价了样本数目、同化时长、背景场误差、观测误差和模型误差对于同化系统性能的影响.结果表明:从计算成本、系统运行时间和同化效果等方面分析,当集合样本数目达到30~40左右时同化系统取得了较好的结果;同化系统对于背景场误差的估计变化不是很敏感,即初始场的估计是否准确对于同化系统的性能影响不是很大;同化系统对于模型误差和观测误差的变化较为敏感,不同的测试点位由于水体动力学性质不一,其敏感性的表现形式有所差异;利用数据同化方法可以有效地估算太湖叶绿素a浓度.;Sensibility of the Lake Taihu chlorophyll-a assimilation system to different parameters directly control the accuracy of estimate the chlorophyll-a concentration distribution when using this assimilation system. We used multispectral data of Environmental Satellite 1(HJ-1), obtained on April 21st, 2009, combined with in situ data to retrieve the concentration of chlorophyll-a in Lake Taihu. We developed a Lake Taihu chlorophyll-a data assimilation system based on ensemble square root Klaman filter(EnSRF) technique. Take the retrieved chlorophyll-a concentration of Lake Taihu as the initial background value, then combined with the data assimilation system to analyze the influence of the ensemble size, the assimilation time, the background error, the observation error and the model error on the assimilation system. The results indicate:taking the computing cost, time cost of system and the performance of the assimilation system into consideration, the assimilation system performs well when the ensemble size are 30-40; the assimilation system is not very sensitive to the accuracy of estimation of the background; both the observation and the model errors are very important for the performance of the system; different test stations have different water dynamic properties, so they have different performance; the estimation of chlorophyll-a concentration can be improved by using the data assimilation method.

Simulation of algal bloom dynamics in a river with the ensemble Kalman filter

A simulation framework of algal bloom in a river channel with data assimilation (DA) was developed by employing two numerical models coupled to simulate a watershed and the embedded river channel. The Hydrological Simulation Program-Fortran (HSPF) model simulates flow discharge and water quality from the subwatersheds and the Environmental Fluid Dynamics Code (EFDC) model takes the subwatershed model outputs at the watershed-river confluence points as boundary forcing to simulate river hydrodynamics and water quality. The ensemble Kalman filter (EnKF) was used for assimilation of water quality variables in the framework, linking uncertainty of model simulation and observation. The simulation uncertainty of the HSPF was quantified at the confluence points as simple stochastic error models developed by comparing the model simulation and the observation. The error models reflect uncertainty of both hydrologic and water quality simulation, including uncertainty associated with point and non-point pollution sources in the watershed. The outputs of the HSPF at the confluence points were perturbed with the error models before used in the following ensemble simulation of the EFDC for the main river. DA was conducted with weekly chlorophyll-a data observed along the river to update chlorophyll-a concentrations of the EFDC model grids. The results showed that the model performance was improved by the assimilation: the root mean square error (RMSE) and the mean continuous probability rank score (CPRS) significantly decreased compared to the open-loop simulation. The updated spatial distribution of chlorophyll-a concentration along the river channel was in reasonable agreement with the observation. Although only chlorophyll-a data was involved in the assimilation, phosphate was selected among other water quality variables for update in order to evaluate the effect of chlorophyll-a assimilation on those variables. It turned out that the phosphate simulation was not much improved by the chlorophyll-a data, which was due to weak correlation between the two variables in the model ensemble. Lastly, chlorophyll-a simulation uncertainty in the river attributed to the simulation uncertainty of each variable in the watershed was evaluated. For that, two additional simulations were made, with perturbation only to flow and phosphate respectively at the confluence points. The spread of chlorophyll-a ensemble of each case became significantly narrower than the original case, indicating that the difference is attributed to the uncertainty of the other unperturbed variables.

Spatial and temporal variations of chlorophyll-a concentration from 2009 to 2012 in Poyang Lake, China

Water eutrophication in Poyang Lake, the largest freshwater lake in China, has been considered to be an obstacle to aquatic environment protection and regional sustainable development. Chlorophyll-a concentration is one of the most important indices of water eutrophication. This paper builds seasonal chlorophyll-a concentration retrieval models using a semi-analytical model. Quarterly distributions of chlorophyll-a concentration from 2009 to 2012 are explored using multi-spectra data from a moderate-resolution imaging spectroradiometer (MODIS). The correlation coefficient of the retrieval models primarily ranged from 0.6 to 0.9. The results show that the chlorophyll-a concentration in Poyang Lake has significant seasonality characteristics that present low values in the winter and spring, and present relatively high values in the summer and autumn; this report also presents an obvious, increasing trend of inter-annual variability from 2009 to 2012. The spatial distribution of the chlorophyll-a concentration has regional differences that give relatively high values adjacent to the shore in the north area of Poyang Lake, in the flow in river entries, and in the main channel area in the central and south areas of Poyang Lake. The natural hydrology features have a close relationship with the variation in the chlorophyll-a concentration. Intensive human activities are the main driving forces for the increasing chlorophyll-a concentration.

A Spectral Decomposition Algorithm for Estimating Chlorophyll-a Concentrations in Lake Taihu, China

The complex interactions among optically active substances in Case II waters make it difficult to associate the variability in spectral radiance (or reflectance) to any single component. In the present study, we developed a four end-member spectral decomposition model to estimate chlorophyll-a concentrations in a eutrophic shallow lake—Lake Taihu. The new model was constructed by simulated spectral data from Hydrolight and was successfully validated using both of simulated reflectance and in situ reflectance data. Using MEdium Resolution Imaging Spectrometer (MERIS) images, the accuracy of the new model was estimated and compared with other published models. According to the MERIS retrieved results, the spatial distribution of chlorophyll-a concentrations and its relationship with environment factors were analyzed. The application of the new model and its limits to estimate water surface chlorophyll-a concentrations in turbid lakes is also discussed.

Spatio-temporal distribution of chlorophyll-a concentration derived from MODIS satellite remote-sensing and in situ observations in Sanya Bay, China

This study examined satellite chlorophyll-a (chl-a) concentration and in situ observations in Sanya Bay (SYB). In situ observation of chl-a was conducted four times per year at 12 sampling stations in SYB from January 2004 to October 2008. Monthly satellite chl-a was derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) during 2000–2012. This study compared satellite chl-a values to in situ measurements in SYB. The two data sets match well in the whole region except for two estuaries. Results show that the average in situ chl-a was 1.49 mg m−3 in SYB. Chl-a was relatively higher (>2 mg m−3) and more variable in coastal areas, with a tendency to decrease offshore (<0.4 mg m−3). The chl-a level in summer displayed obviously vertical stratification, with higher values at the bottom and lower values at the surface. Analysis of monthly mean chl-a showed that the highest level (>2 mg m−3) appeared in December, with the lowest in March (<1 mg m−3). The gradients are ranked winter, autumn, summer and spring. There was higher chl-a in autumn and winter, which may be associated with the stronger wind monsoon then. Annual mean chl-a from 2000 to 2012 varied from 1.17 to 2.05 mg m−3, with the minimum in 2001 and the maximum in 2005. The chl-a level presented a roughly increasing tendency from 2000 to 2012, which may be related to the increasing nutrients associated with the development of tourism and fishery.

Nutrients distribution in the coastal water of East Asia relative to the Kuroshio

Nutrients in the coastal water of East Asia were surveyed from the point of contribution of the diluted water to the open water relative to the Kuroshio, the western boundary current. The Kuroshio runs along eastern Asia, sensing changes in environment in the coastal region. The nutrients-depleted water from the Kuroshio, close to the coastal water, provides heat energy and high saline water. The fresh water from the river contributes to the coastal water as diluted water and exhibits the entrainments of nutrient water into the Kuroshio. The nutrients are important parameters to monitor the interactions among the Kuroshio and inland waters. Nutrients exhibited a wide range of ratio between nitrate to phosphate, nitrate to silicate, and silicate to phosphate in East Asia as divergences from the Redfield ratios. The distribution of nutrients could also be monitored as the distribution of chlorophyll-a concentration using the ocean color sensors. Contrasts in chlorophyll-a concentration between the oligotrophic water of the Kuroshio and the trophic water of the coastal region exhibit the mixing process of two water masses. Although the chlorophyll-a concentrations estimated by the current ocean color algorithm over the coastal water are of insufficient accuracy, the distribution of chlorophyll-a concentration exhibits a variation of seasonal consumption of nutrients and response to the Kuroshio and river runoff.

Mapping and Modeling Chlorophyll-&lt;I&gt;a&lt;/I&gt; Concentration in Utah Lake Using Landsat 7 ETM+ Imagery

Mapping and Modeling Chlorophyll-a Concentrations in Utah Lake Using Landsat 7 ETM+ Imagery Victor Nii Afum Narteh Department of Civil & Environmental Engineering, BYU Master of Science This study shows the results of testing previous research that used remote sensing techniques to determine chlorophyll-a concentrations in turbid surface waters, and developing similar methods and models for Utah Lake using Landsat 7 ETM+ satellite imagery and field measured concentrations of chlorophyll-a. The data for the study included images acquired on June 22 and July 8, 2009. The field data included ground measurements taken on June 22 and July 6, 2009 from seven water quality sampling locations. The 48 hour time difference between the Landsat image acquisition (July 8) and the field measurement (July 6), and the small sample size for the data analysis were potential sources of error. The log transformation of red/near-infrared reflectance (i.e. ln[Band3/Band4]) had a high correlation with the field measured chlorophyll-a concentrations (R 2 = 0.9337). With this relationship, a model and 19 contour maps showing the spatial distribution of chlorophyll-a concentrations over Utah Lake was developed for the spring, summer, and fall seasons of 2003 to 2010. Generally about 90% of the Lake area had chlorophyll-a concentrations lower than 20μg/L. High concentrations of Chlorophyll-a (355μg/L and over) were observed mostly at the Provo Bay and Goshen Bay areas of the Lake. Occasionally, elevated levels of chlorophyll-a were observed at the northeastern, middle, and western sections of the lake. Utah Lake’s average chlorophyll-a concentration is declining over time. In spring, the Lake average chlorophyll-a concentration reduced from 30.51μg/L in 2004 to 7.08μg/L in 2010. In summer, this average reduced from 132.13μg/L in 2003 to 36.58μg/L in 2010. Finally, in fall, the Lake average chlorophyll-a concentration reduced from 273.40μg/L in 2006 to 33.59μg/L in 2010. Field measured concentrations of phosphorus and model estimates for chlorophyll-a concentrations were highly correlated (R 2 = 0.9046). This suggests that the elevated levels of chlorophyll-a might be a result of the point and non-point discharge of phosphorus-laden wastewater from treatment plants, municipal storm drains, and agricultural activities. .

Phytoplankton Tracking by Oceanic Model and Satellite Data in the Bay of Bengal and Andaman Sea

Chlorophyll-a and phytoplankton concentrations at the sea surface reduce CO2, increase O2 and indicate the abundance of fish. If they are well understood, there are enormous benefits. This study investigates the seasonal distribution of Chlorophyll-a and phytoplankton concentrations in the Bay of Bengal and Andaman Sea by the created oceanic model and the satellite data obtained from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and Moderate Resolution Imaging Spectroradiometer (MODIS). The time-series and distribution of Chlorophyll-a concentration, phytoplankton absorption coefficient and Sea Surface Temperature are retrieved from Giovanni to analyze. The simulation is created from the seasonal winds to give the surface circulation as a result. The work is done to compare the satellite data and the simulation result. They are found to be agreed between SST, Chl-a concentration, phytoplankton absorption coefficient and ocean surface circulation. The study reaches the conclusion that the oceanic model can implicitly describe the seasonal distribution of Chlorophyll-a and phytoplankton concentrations in the domain of study.

Seasonal dynamic and spatial distribution of chlorophyll-a concentration in Lake Erhai

2010年5月至2011年4月,对洱海叶绿素a的季节动态、空间分布及其与环境因子的关系进行研究.结果表明,水体中叶绿素a浓度存在明显的季节变化,其变化范围为4.11~24.30μg/L,年平均值为10.4±6.5μg/L,最小值出现在2011年3月,最大值出现在2010年9月.叶绿素a浓度在夏、秋季较高,冬、春季较低.在空间变化上,叶绿素a浓度在南部湖区最大,其次是北部湖区,中部湖区最低.Pearson相关系数和主成分分析表明,洱海叶绿素a浓度在不同湖区中与水温和透明度均呈极显著相关.总氮在北部和南部湖区与叶绿素a浓度均存在一定的相关性,而总磷与叶绿素a浓度在南部湖区存在一定的相关性.根据修正的卡尔森营养状态指数,洱海综合TSI值为50.6,水质处于中营养状态.;Seasonal dynamics and spatial distributions of chlorophyll-a concentration and its relationship to environmental factors in Lake Erhai from May 2010 to April 2011 were investigated. Results showed that the seasonal dynamics of chlorophyll-a concentration in Lake Erhai were obvious, ranging from 4.11 to 24.30 μg/L and with the annual mean value 10.4 ± 6.5 μg/L. The minimum and maximum of chlorophyll-a concentration appeared in March and September, respectively. The chlorophyll-a concentrations were much higher in summer and autumn while relatively lower in winter and spring. Spatially, chlorophyll-a concentrations were the highest in the southern zones of the lake, followed by the northern and the middle zones. Pearson correlations and principal component analysis suggested that the chlorophyll-a concentration has negative correlation with transparency in different zones of Lake Erhai, while has positive correlation with water temperature. The chlorophyll-a concentration was correlated significantly with total nitrogen in the northern and southern zones of Lake Erhai, while correlated with total phosphorus in southern zones. Based on the modified Carlson trophic state index, the comprehensive TSI was 50.6 in Lake Erhai, indicating a mesotrophic state.

Mapping Potential Fishing Grounds in Lake Malawi Using AVHRR and MODIS Satellite Imagery

This paper discusses a procedure that was developed to delineate potential fishing grounds in Lake Malawi using data on chlorophyll-a concentration derived from Moderate-resolution Imaging Spectroradiometer (MODIS/AQUA) in combination with lake surface temperature (LST) data obtained from Advanced Very High Resolution Radiometer (AVHRR) and MODIS/Terra satellite sensors. The paper draws from findings of studies [1,2] on development of algorithms for estimating chlorophyll-a and lake surface temperature in Lake Malawi from satellite imagery, respectively. To estimate chlorophyll concentration (a proxy for phytoplankton) in Lake Malawi using data from MODIS satellite imagery, in situ measurements of chlorophyll concentration were conducted at three selected sampling stations over the southeastern arm of Lake Malawi concurrent with satellite image acquisitions. These were regressed on chlorophyll-a concentration values obtained from Ocean Color (MODIS/AQUA) Data using SeaWIFS Data Analysis System (SeaDAS) software. From this, an equation for estimating chlorophyll-a concentration in Lake Malawi from MODIS satellite imagery was developed and used for mapping the spatial distribution of chlorophyll-a concentration in the lake. Since Lake Malawi is an oligotrophic lake, with an average value of chlorophyll concentration of 1 μg/L, areas in the lake with relatively high chlorophyll-a concentration were identified as potential locations for the development of the fishery industry. Estimation of lake surface temperature using satellite imagery involved two main activities. Firstly, in situ measurements of lake surface temperature were conducted at the three selected sampling stations over Lake Malawi concurrent with satellite image acquisitions. The second activity involved downloading and processing AVHRR and MODIS/Terra satellite imagery. AVHRR data covered the period September 1997 to February 1998 whereas MODIS/Terra data covered the period May to November, 2006. Both MODIS Land Surface Temperature (MOD11A1) and Ocean Color Sea Surface Temperature (SST) were downloaded from EOS Gateway website and processed into lake surface temperature. Two glass thermometers were used to measure temperature directly from the lake surface at a depth of 0 - 7.0 cm (i.e., skin temperature) and the average of the two readings was recorded as the lake surface temperature at a particular sampling station. Observed temperatures were regressed on remotely sensed data. ER Mapper was employed in drawing maps showing the distribution of lake surface temperature using the regression equation that was developed. Upwelling and downwelling zones were demarcated from lake surface temperature maps. Upwelling zones were identified as areas with a high potential for the development of the fishery industry because of their association with primary productivity. Using a simple overlay technique, data from both the spatial and temporal distribution of chlorophyll-a and lake surface temperature were used to delineate potential fishing grounds in Lake Malawi. The zone extending from Salima up to the northern part of Nkhotakota and the area on the northeastern tip of Lake Malawi were identified as areas of high primary productivity and therefore potential fishing grounds. These areas generally exhibit persistent cool surface waters, indicative of upwelling; and have relatively abundant phytoplankton.

Detection of biological films observed by PALSAR ScanSAR mode and Fine mode under the different winds

The archipelagoes in Philippine were selected to discuss a possibility to detect biological films by the Synthetic Aperture Radar (SAR). The ScanSAR Mode and the Fine mode of the ALOS PALSAR data were applied to represent the sea surface roughness. The distributions of chlorophyll-a concentration observed by the MODIS were used to discuss a contribution of biological films. The reanalysis wind data from the National Centers for Environmental Prediction (NCEP) were applied to distinguish wind fields of observation site. The Fast Fourier Transform (FFT) was applied to the surface roughness image observed by SAR to identify a directional component of wind wave and a power distribution in the frequency domain. A detection matrix of the biological films was created from the power spectrum distribution, chlorophyll-a, wind data, and discussed for the detection of biological films. From the interaction among chlorophyll-a concentration, surface winds, and sea surface roughness, the fine SAR image was more sensitive than the ScanSAR image for the detection of biological films.