Correlation between concentrations of chlorophyll-a and satellite derived climatic factors in the Persian Gulf (original) (raw)
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Journal of Marine Systems, 2010
Possible factors regulating phytoplankton variability in the Arabian (Persian) Gulf were analyzed on the basis of satellite observations and meteorological data (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009), including remotely-sensed chlorophyll a concentration (CHL), sea surface temperature, wind, solar radiation, precipitation, and aerosols. Shallow waters of northwestern Gulf influenced by Shatt Al-Arab River discharge were more productive than open Gulf waters, although seasonal CHL patterns in this and other shallow regions looked unrealistic likely because the CHL signal was obscured by bottom reflection. Therefore our further analyses focused on the open Gulf waters, which show a subtropical seasonal CHL cycle with maximum in winter and minimum in spring-summer. This cycle, however, was decoupled from the seasonal extremes of wind mixing. Interannual variations of CHL in the open Gulf regions were correlated with precipitation and aerosol data rather than with wind and sea surface temperature, consistent with the hypothesis of atmospheric deposition as a factor regulating phytoplankton growth. The effect of dust fertilization was likely observed in 2000 and 2008, when low precipitation and aerosol properties indicating elevated level of aeolian dust transport were followed by phytoplankton blooms.
A STUDY ON THE EFFECT OF DUST AND WIND ON PHYTOPLANKTON ACTIVITIES IN THE ARABIAN GULF
Red Tide occurrences in the Arabian Gulf have increased in the last few years. It damaged the aquatic life and the economic side of the region. Red tide is the presence of algae blooms (phytoplankton) which can be harmful, toxic and affects human health. The Arabian Gulf is an enclosed shallow basin surrounded by desert and arid areas. Not adequate remote sensing studies have been done on the dynamic of physical and biological properties of this water body. The correlations between red tide, described as OC3-derived Chlorophyll-a concentration (mg m-3), and other related parameters such as: fluorescence line height (FLH W m-2 μm-1 sr-1), aerosol optical thickness (AOT), wind speed (m/s) and sea surface temperature (o C) were studied. It was found that chlorophyll concentration is affected directly by dust loading, temperature, and wind and nutrients availability.
Monthly Variability of Chlorophyll-α Concentration in Persian Gulf Using Remote Sensing Techniques
During the last two decades, large-scale high biomass algal blooms of the dinoflagellate Cochlodinium have occurred frequently. Prior to 1990, blooms had been primarily reported in Southeast Asia. Since then, time blooms have expanded across Asia, Europe and North American. A multi-spectral classification and quantification technique is developed for estimating chlorophyll-α concentrations. In this study, we explored the use of Sea-viewing Wide Field of-view Sensor (SeaWiFS) satellite data in studying the spatio-temporal changes in chlorophyll-α concentration in Persian Gulf. In addition, the present study focuses on the temperature, dissolved oxygen, salinity, pH and nutrient concentrations during the red tide phenomenon. The resultant chlorophyll-α concentration images derived from SeaWiFS satellite data give an indication of the monthly spatial variation in chlorophyll-α concentration from 2008 to 2009. Variability of chlorophyll-α plot from September 2008 to May 2009 in Persian Gulf showed that September 2008 had the lowest value (1.57±0.14 mg m-3) than other years except May 2009, then tended to increase up to January 2009 (Highest value: 7.47±1.67mg m-3), then a slow decrease up to May 2009. The result showed all water physicochemical parameters measurement in-situ (DO and pH) and ex-situ (NO 3 and PO 4), were varied among the different months. The highest and lowest values of these parameters were recorded in September 2008 and May 2009, respectively. After occurrence of the red tide, nutrient concentration (NO 3 and PO 4), dissolved oxygen and pH were reduce compared to before this phenomenon. Compare mean between various months' showed significant differences for temperature records among the months of study (p≤0.05). Lowest and highest temperature recorded were in February 2009 and September 2008, respectively, but no significant differences were found in salinity (p≥0.05). This study showed that SeaWiFS satellite data provide useful information on the spatio-temporal variations in Persian Gulf, which is useful in establishing general trends that are more difficult to determine through routine ground measurements. ABSTRAK Sepanjang dua dekad yang lalu, ledakan alga biojisim berskala dinoflagellate Cochlodinium telah berlaku dengan kerap. Sebelum tahun 1990, ledakan selalunya dilaporkan di Asia Tenggara. Sejak itu, masa ledakan telah merebak ke seluruh Asia, Eropah dan Amerika utara. Pengelasan pelbagai tatacara dan teknik mengkuantifikasi dibangunkan untuk menganggar kepekatan klorofil-α. Dalam kajian ini, kami mengkaji penggunaan sensor pandangan laut bidang luas pandangan (SeaWiFS) data satelit dalam mengkaji perubahan spatio-temporal dalam kepekatan klorofil-α di Teluk Parsi. Di samping itu, kajian ini tertumpu kepada suhu, oksigen terlarut, kemasinan, kepekatan pH dan nutrien semasa fenomena pasang-surut merah. Kepekatan klorofil-α imej terhasil yang diperoleh daripada SeaWiFS data satelit memberi petunjuk variasi bulanan reruang dalam kepekatan klorofil-α dari 2008 ke 2009. Kebolehubahan plot klorofil-α dari September 2008 hingga Mei 2009 di Teluk Parsi menunjukkan bulan September 2008 mempunyai nilai terendah (1.57±0.14 mg m-3) berbanding tahun lain kecuali Mei 2009 yang kemudian terus meningkat sehingga Januari 2009 (nilai tertinggi 7.47±1.67 mg m-3), selepas itu penurunan perlahan sehingga ke Mei 2009. Hasil kajian menunjukkan semua pengukuran parameter fizikokimia air in-situ (DO dan pH) dan ex-situ (NO 3 dan PO 4) adalah berbeza-beza antara bulan. Nilai parameter tertinggi dan terendah ini direkodkan masing-masing pada bulan September 2008 dan Mei 2009. Selepas kejadian pasang-surut merah, nutrien kepekatan (NO 3 dan PO 4), oksigen terlarut dan pH berkurangan berbanding sebelum fenomena ini. Min bandingan antara bulan menunjukkan perbezaan yang signifikan untuk rekod suhu antara bulan kajian (p≤0.05). Suhu terendah dan tertinggi masing-masing direkod pada Februari 2009 dan September 2008, tetapi tiada perbezaan yang bererti untuk kemasinan (p≥0.05). Kajian ini menunjukkan data satelit SeaWiFS memberikan maklumat berguna tentang variasi spatio-temporal di Teluk Parsi dalam mewujudkan trend umum yang lebih sukar untuk ditentukan melalui pengukuran tanah rutin.
Aquatic Ecology, 2010
We present data from a long time-series study to describe the factors that control phytoplankton population densities and biomass in the coastal waters of Oman. Surface temperature, salinity, nutrients, dissolved oxygen, chlorophyll a (Chl a), and phytoplankton and zooplankton abundance of sea water were measured as far as possible from February 2004 through February 2006, at two stations along the southern coast of the Gulf of Oman. The highest concentrations of Chl a (3 mg m−3) were recorded during the southwest monsoon (SWM) when upwelling is active along the coast of Oman. However, results from our study reveal that the timing and the amplitude of the seasonal peak of Chl a exhibited interannual variability, which might be attributed to interannual differences in the seasonal cycles of nutrients caused either by coastal upwelling or by cyclonic eddy activity. Monthly variability of SST and concentrations of dissolved nitrate, nitrite, phosphate, and silicate together explained about 90% of the seasonal changes of Chl a in the coastal ecosystem of the Gulf of Oman. Phytoplankton communities of the coastal waters of Oman were dominated by diatoms for most part of the year, but for a short period in summer, dinoflagellates were dominant.
This study focuses on applying remote sensing technology to identify and assess seasonal and intra-annual variation of phytoplankton availability. A standard MODIS algorithm for Chlorophyll-a, is used to obtain a variation of phytoplankton with the help of MODIS time series images from April 2011 to March 2012 that describe the situation for a whole year, we also used periodical data for each three months, i.e., . Chlorophyll-a (Chl-a), products were retrieved from the sensor data that demonstrates the spatio-temporal variability of phytoplankton concentration in the northern Arabian sea near the coastline and open sea water of Pakistan, India, Iran and Oman. High concentration of Chl-a, were observed during two periods August to September and February to March respectively. It was also revealed that Chl-a, concentration was almost identical between the latitude 20 and 21 degrees N throughout the year.
International Journal of Marine Science, 2015
The impact of long term variation in sea surface temperature (SST) on marine biomass using long-term satellite remote sensing data (1985-2006) for SST and (1998-2010) for chlorophyll-a was studies. This paper presents the result of the analysis conducted on twenty one year's data on high-quality satellite derived Sea Surface Temperature, and twelve years SeaWiFS chlorophyll-a data from Arabian Sea. The results are extracted after processing the data using statistical methods for computation of inter-annual seasonal mean and standard deviation. The mean winter data show that region consisting on Gulf of Oman is colder (< 21 o C) than the rest of Arabian Sea. However, annual mean of winter show the intermittent rise and fall in
Journal of Space Technology, 2019
This study aims to employ remote sensing as a means to ascertain the marine productive zones through the correlative relationship between Sea Surface Temperature (SST) and Chlorophyll-a (Chl-a) concentration. We used monthly data sets of SST and Chl-a concentrations at 4 km resolution, obtained from Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) from the year 2001 to 2017. The study of Chl-a enrichment in certain parts of Arabian Sea and the Persian Gulf is generally associated with the variability of SST. This study demonstrates the usability of satellite data which can be greatly enhanced by the use of Data Interpolating Empirical Orthogonal Functions (DINEOF) method, which in turn has proven a reliable tool for finding the missing data due to cloud covers especially in the months of SW monsoon in the region under study. Monitoring of Spatial and temporal distributions of SST and Chl-a concentration in different seasons indicated that most of the study area (96%) exhibited negative correlation between SST and Chl-a. Just a few regions (4%) including some coastlines and Persian Gulf show positive correlation, indicating the impact of some oil spills and human interaction with seawater quality. Marine productivity has a pivotal character to play in the socioeconomic development of countries, located around the Arabian sea and this study could be beneficial to find the spatial association of SST and Chl-a with marine productive zones.
International Journal of Remote Sensing, 2011
Monthly chlorophyll-a (Chl-a) concentrations derived from SeaWiFS data for 1997-2005 and chlorophyll measurements from the Atlantic Meridional Transect for 1995-2001 have been analysed to describe seasonal and inter-annual variability of surface Chl-a in the Mauritanian upwelling. There was a moderate to strong correspondence between the seasonal cycles of surface Chl-a and the seasonal cycles of ocean physical and meteorological fields (such as sea-surface temperature, seasurface height, and prevailing wind), with a noticeable exception in 1998 that corresponded to a strong anomalous Chl-a event ($250% increase) in the Mauritanian upwelling. Alongshore wind-stress and wind-stress curl were found to be the most significant factors controlling the variability of Chl-a (jointly explaining more than 50% of total variance). The biological response to the alongshore wind-stress was immediate, but it lagged the wind-stress curl by 1-2 months (each explaining more than 40% of the total Chl-a variability). These observations also demonstrate a link, hitherto unreported, between the Pacific El-Nin˜o Southern Oscillation (ENSO) and anomalous Chl-a field in the Mauritanian upwelling. The multivariate ENSO index was shown to account for a significant part of the variability of the autumn-winter Chl-a anomaly (r ¼ À0.52, po0.01). A cold event, following an intense El Nin˜o in the Pacific during summer, was found to mirror the intensity of wind forcing and phytoplankton concentration in the Mauritanian upwelling a few months later. Therefore, ENSO-related changes in the local atmospheric fields are considered as the preferred candidates for explaining the observed biological changes in the Mauritanian upwelling during 1998Mauritanian upwelling during -1999
Evaluation of Satellite Retrievals of Chlorophyll-a in the Arabian Gulf
The Arabian Gulf is a highly turbid, shallow sedimentary basin whose coastal areas have been classified as optically complex Case II waters (where ocean colour sensors have been proved to be unreliable). Yet, there is no such study assessing the performance and quality of satellite ocean-colour datasets in relation to ground truth data in the Gulf. Here, using a unique set of in situ Chlorophyll-a measurements (Chl-a; an index of phytoplankton biomass), collected from 24 locations in four transects in the central Gulf over six recent research cruises (2015–2016), we evaluated the performance of VIIRS and other merged satellite datasets, for the first time in the region. A highly significant relationship was found (r = 0.795, p < 0.001), though a clear overestimation in satellite-derived Chl-a concentrations is evident. Regardless of this constant overestimation, the remotely sensed Chl-a observations illustrated adequately the seasonal cycles. Due to the optically complex environment, the first optical depth was calculated to be on average 6–10 m depth, and thus the satellite signal is not capturing the deep chlorophyll maximum (DCM at ~25 m). Overall, the ocean colour sensors' performance was comparable to other Case II waters in other regions, supporting the use of satellite ocean colour in the Gulf. Yet, the development of a regional-tuned algorithm is needed to account for the unique environmental conditions of the Gulf, and ultimately provide a better estimation of surface Chl-a in the region.