Strong enhancement of chlorophyll a concentration by a weak typhoon

Recent studies demonstrate that chlorophyll a (chl a) concentrations in the surface ocean can be significantly enhanced due to typhoons. The present study investigated chl a concentrations in the middle of the South China Sea (SCS) from 1997-2007. Only the Category1 (minimal) Typhoon Hagibis (2007) had a notable effect on the chl a concentrations. Typhoon Hagibis had a strong upwelling potential due to its location near the equator, and the forcing time of the typhoon (>82 h) was much longer than the geostrophic adjustment time (~63 h). The higher upwelling velocity and the longer forcing time increased the depth of the mixed-layer, which consequently induced a strong phytoplankton bloom that accounted for about 30% of the total annual chl a concentration in the middle of the SCS. The implication is that the forcing time of a typhoon should be long enough to establish a strong upwelling and consequently for the induction of significant upper ocean responses.Comment: Typhoon-Ocean Environment interaction

Chlorophyll-A Estimation from Remotely Sensed Data

The science of remote sensing is commonly defined as method that employs electromagnetic energy to detect, record, and measure characteristics of a target. Concentrations of chlorophyll-a in water have been estimated from the spectral distribution of back-scattered light, related to reflectance. Remote sensing in general has been used much more extensively for oceans than for inland waters. Advanced image processing techniques introduced and applied using Landsat Thematic Mapper data acquired on February 22, 1 994 over the indicated region of South China Sea. The objective of the study was to calculate the chlorophyll-a concentration along Kuala Terengganu. The method was carried out to calculate the chlorophyll-a concentration in the study area that is, digital image processing which include preprocessing, display, enhancement, information extraction, and algorithm to calculate the estimated chlorophyll-a. Results of the regression analysis of DNs against referenced chlorophyll-a was used to calculate the actual chlorophyll-a concentration (calculated chlorophyll-a) of Landsat TM bands 1, 2, and 3. The results show that the chlorophyll-a concentrations in the study area are significantly correlated with band 1, 2, and 3. The lower chlorophyll-a concentration with levels (0.031-0.019) mg/m3, the higher chlorophyll-a concentration with levels (0.404-0.391) mg/m3. Finally, band 2 was the best in terms of all the parameters evaluated. In conclusion, remote sensing is an important technology for measuring chlorophyll-a concentration in the coastal water of South China Sea. From the result, TM sensor has been found a useful tool for studying chlorophyll-a concentration

Analysis the Spread of Chlorophyll-A Concentration in Birah-Birahan Island Waters Using Landsat 8 Images

ABSTRACT: Research aims to determine the value of concentration and spread profile of chlorophyll-a in Birah-birahan Island waters. To process the spread profile data of chlorophyll-a concentration in Birah-Birahan Island waters, the data were used is Landsat 8 imagery data in 2018, i.e. February and August and February and October in 2019, data processing uses the er-mapper and arcgis application by using the Pentury algorithm and Hanintyo algorithm. Information was obtained that the value of chlorophyll-a concentration used the pentury algorithm in 2018, February on west monsoon, i.e. 0.06 mg/m3 and August on east monsoon, i.e. 0.07 mg/m3, in 2019 February on west monsoon, namely 0.06 mg/m3 and October on east monsoon is 0.07 mg/m3 and chlorophyll-a concentration value using the Hanintyo algorithm in 2018 February on west monsoon i.e. 0.22 mg/m3 and August in the east monsoon is 0.27 mg/m3, in 2019 February on west monsoon i.e. 0.25 mg/m3 and October on east monsoon i.e. 0.24 mg/m3. It can be concluded that the concentration value by the pentury and Hanintyo algorithm of two different years in west and east monsoon the highest chlorophyll-a concentration value were known based on Hanintyo algorithm.   Keywords: Chlorophyll-a, Landsat 8, Spread, Birah-Birahan Island

Inter-annual variability and seasonal dynamics in lipid signatures of Leiognathus splendens (Cuvier, 1829)

Seasonal variations (pre-monsoon, monsoon and post-monsoon) of the lipid, fatty acid and total cholesterol profile in edible tissues of silver belly Leiognathus splendens collected from the south west (SW) and south east (SE) coasts of India over four years (2008-2011) were investigated in this study. The correlations between the fatty acid compositions with seasonal chlorophyll-a concentration of these years were also evaluated. The lipid levels showed pronounced seasonal fluctuations with the highest values occurring in the post-monsoon season and showed a good correlation with chlorophyll-a concentration. The lipid levels showed pronounced seasonal fluctuations with highest values occurring in post-monsoon season and showed strong correlation with chlorophyll-a concentration. Eicosapentaenoic acid correlated with chlorophyll-a concentration during monsoon in SW coast, and monsoon, post-monsoon in the SE coast. The correlation patterns of fatty acids with chlorophyll-a concentration were also studied. Similarly, the health indices such as atherogenic index, thrombogenicity index, total cholesterol, and hypocholesterolemic/hypercholesterolemic ratio of Leiognathus splendens were found to be ideal, which contributed towards its parameters to be qualified as an ideal health food

Ocean color algorithm for remote sensing of chlorophyll

An algorithm for the remote detection of chlorophyll a in the ocean was tested during a Nantucket Shoals experiment conducted by NASA. A set of Multichannel Ocean Color Sensor (MOCS) data selected from one flight for each of the two altitudes flown was used to calibrate the algorithm for chlorophyll a concentration. The equations were then applied to all unsaturated MOCS data collected during the 8-day experiment to generate contour maps of chlorophyll a concentration over the shoals. One additional flight was conducted away from the shoals both on and off the Continental Shelf. Although no solar elevation or environmental corrections were made to the original conversions, the equations in these tests determined chlorophyll a concentrations to an accuracy better than 1.0 micron g/L despite the fact that the solar elevation varied between 20 deg and 56 deg during the data collection periods of the experiments

Spatial-Temporal Variability of Chlorophyll-a Concentration in Cenderawasih Bay and Surrounding Waters

Chlorophyll-a is one of the parameters determining the primary productivity of water. In the fisheries sector, information on chlorophyll-a concentration in marine waters is very important for the prediction of fishing grounds. This study aims to analyze the variability of chlorophyll-a concentrations in Cenderawasih Bay and the surrounding waters, both spatial and temporal variability. Data from the Aqua-MODIS Level 3 monthly composite period from January to December 2019 was used to determine the concentration of chlorophyll-a. Time-series data are used to determine fluctuations of chlorophyll-a concentrations, while interpolation with the kriging method is used to determine the spatial distribution of chlorophyll-a. The analysis showed that the monthly average value of chlorophyll-a concentration in the study area ranged from 0.1988 – 0.3415 mg.m-3. The average value of chlorophyll-a concentration increases from March to June and then decreases in July or August. The highest average chlorophyll-a concentration was in March and the lowest in January. The maximum chlorophyll-a concentration in April and the minimum in August, which is around 9.1089 mg.m-3 and 0.0975 mg.m-3, respectively. The concentration of chlorophyll-a in Cenderawasih Bay and its surrounding waters is dominated by a low concentration, which ranges 0.1482 – 0.3158 mg.m-3. Generally, the variability of chlorophyll-a concentrations in the study area is influenced by seasons. The average chlorophyll-a concentration is high in the Transition I (West-east) and East seasons and will decrease in Transition II (East-West) until the West season. Spatially, chlorophyll-a concentrations in coastal areas are higher than in offshore waters. High chlorophyll-a concentrations are found around the border between Nabire Regency and Waropen Regency. The amount of run-off flow that supplies nutrients from the mainland greatly affects the high concentration of chlorophyll-a in the coastal area

Boosted Beta regression.

Regression analysis with a bounded outcome is a common problem in applied statistics. Typical examples include regression models for percentage outcomes and the analysis of ratings that are measured on a bounded scale. In this paper, we consider beta regression, which is a generalization of logit models to situations where the response is continuous on the interval (0,1). Consequently, beta regression is a convenient tool for analyzing percentage responses. The classical approach to fit a beta regression model is to use maximum likelihood estimation with subsequent AIC-based variable selection. As an alternative to this established - yet unstable - approach, we propose a new estimation technique called boosted beta regression. With boosted beta regression estimation and variable selection can be carried out simultaneously in a highly efficient way. Additionally, both the mean and the variance of a percentage response can be modeled using flexible nonlinear covariate effects. As a consequence, the new method accounts for common problems such as overdispersion and non-binomial variance structures