Multi-sensor satellite time series of optical properties and chlorophyll-a concentration in the Adriatic Sea

2011 ◽  
Vol 91 (3) ◽  
pp. 229-244 ◽  
Author(s):  
F. Mélin ◽  
V. Vantrepotte ◽  
M. Clerici ◽  
D. D’Alimonte ◽  
G. Zibordi ◽  
...  
Keyword(s):  
Time Series ◽  
Optical Properties ◽  
Chlorophyll A ◽  
Adriatic Sea ◽  
Chlorophyll A Concentration

scholarly journals Seasonal Cycles of Phytoplankton Expressed by Sine Equations Using the Daily Climatology from Satellite-Retrieved Chlorophyll-a Concentration (1997–2019) Over Global Ocean

2020 ◽  
Vol 12 (16) ◽  
pp. 2662 ◽  
Author(s):  
Zexi Mao ◽  
Zhihua Mao ◽  
Cédric Jamet ◽  
Marc Linderman ◽  
Yuntao Wang ◽  
...  
Keyword(s):  
Time Series ◽  
Chlorophyll A ◽  
Seasonal Variations ◽  
Global Ocean ◽  
Boreal Winter ◽  
Seasonal Cycles ◽  
Chlorophyll A Concentration ◽  
Chl A ◽  
Global Oceans ◽  
Sine Equation

The global coverage of Chlorophyll-a concentration (Chl-a) has been continuously available from ocean color satellite sensors since September 1997 and the Chl-a data (1997–2019) were used to produce a climatological dataset by averaging Chl-a values at same locations and same day of year. The constructed climatology can remarkably reduce the variability of satellite data and clearly exhibit the seasonal cycles, demonstrating that the growth and decay of phytoplankton recurs with similarly seasonal cycles year after year. As the shapes of time series of the climatology exhibit strong periodical change, we wonder whether the seasonality of Chl-a can be expressed by a mathematic equation. Our results show that sinusoid functions are suitable to describe cyclical variations of data in time series and patterns of the daily climatology can be matched by sine equations with parameters of mean, amplitude, phase, and frequency. Three types of sine equations were used to match the climatological Chl-a with Mean Relative Differences (MRD) of 7.1%, 4.5%, and 3.3%, respectively. The sine equation with four sinusoids can modulate the shapes of the fitted values to match various patterns of climatology with small MRD values (less than 5%) in about 90% of global oceans. The fitted values can reflect an overall pattern of seasonal cycles of Chl-a which can be taken as a time series of biomass baseline for describing the state of seasonal variations of phytoplankton. The amplitude images, the spatial patterns of seasonal variations of phytoplankton, can be used to identify the transition zone chlorophyll fronts. The timing of phytoplankton blooms is identified by the biggest peak of the fitted values and used to classify oceans as different bloom seasons, indicating that blooms occur in all four seasons with regional features. In global oceans within latitude domains (48°N–48°S), blooms occupy approximately half of the ocean (50.6%) during boreal winter (December–February) in the northern hemisphere and more than half (58.0%) during austral winter (June–August) in the southern hemisphere. Therefore, the sine equation can be used to match the daily Chl-a climatology and the fitted values can reflect the seasonal cycles of phytoplankton, which can be used to investigate the underlying phenological characteristics.

Optical properties of the red tide in Isahaya Bay, southwestern Japan: Influence of chlorophyll a concentration

2008 ◽  
Vol 64 (4) ◽  
pp. 511-523 ◽  
Author(s):  
Hiroaki Sasaki ◽  
Akihiko Tanaka ◽  
Mitsunori Iwataki ◽  
Yasuharu Touke ◽  
Eko Siswanto ◽  
...  
Keyword(s):  
Optical Properties ◽  
Chlorophyll A ◽  
Red Tide ◽  
Chlorophyll A Concentration ◽  
Isahaya Bay

scholarly journals Temporal variability of 10-year global SeaWiFS time-series of phytoplankton chlorophyll a concentration

2009 ◽  
Vol 66 (7) ◽  
pp. 1547-1556 ◽  
Author(s):  
V. Vantrepotte ◽  
F. Mélin
Keyword(s):  
Time Series ◽  
Chlorophyll A ◽  
Temporal Variability ◽  
Global Scale ◽  
Wide Field ◽  
Seasonal Component ◽  
Ocean Colour ◽  
Chlorophyll A Concentration ◽  
Chl A ◽  
The Stability

Abstract Vantrepotte, V., and Mélin, F. 2009. Temporal variability of 10-year global SeaWiFS time-series of phytoplankton chlorophyll a concentration. – ICES Journal of Marine Science, 66: 1547–1556. The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) global dataset now offers a 10-year time-series of a consistent, well-calibrated, ocean colour record suitable to analyse temporal variability. The relative importance of the seasonal term in the chlorophyll a (Chl a) concentration signal is first assessed using statistical techniques of temporal decomposition. The emphasis is on the Census method II (X-11) approach, which allows year-to-year variations in the seasonal component. The seasonality detected in the SeaWiFS Chl a record is analysed through a generic province-based classification of marine ecosystems and at global scale and is found very variable spatially. Working with 5′-resolution gridded Chl a products, the contribution of the seasonal component derived from X-11 amounts to 64% of the total variance, compared with only 36% if a fixed annual cycle is assumed. The capacity of X-11 to capture interannual variations in seasonality is used to diagnose the stability of the Chl a seasonal cycle. Finally, linear changes in Chl a concentration observed after a decade of continuous ocean colour record agree globally with previous observations on shorter series. Significant changes of both signs are detected in various regions of the world’s oceans, but primarily a general decrease of Chl a in the mid-ocean gyres.

scholarly journals NW Adriatic Sea biogeochemical variability in the last 20 years (1986–2005)

2007 ◽  
Vol 4 (4) ◽  
pp. 673-687 ◽  
Author(s):  
L. Tedesco ◽  
G. Socal ◽  
F. Bianchi ◽  
F. Acri ◽  
D. Veneri ◽  
...  
Keyword(s):  
Time Series ◽  
Chlorophyll A ◽  
Adriatic Sea ◽  
Light Attenuation ◽  
Nutrient Inputs ◽  
The North ◽  
Western Area ◽  
Offshore Station ◽  
Trends Over Time

Abstract. This paper presents a long-term time series (1986–2005) of hydrological and biogeochemical data, both published and unpublished. Data were collected in the north-western area of the Adriatic Sea, at two stations that are considered hydrodynamically and trophically different. The time series have been statistically and graphically analysed on a monthly scale in order to study the annual climatologies, links between the concentrations of chlorophyll-a and the variability in the environment, trophic differences between the two areas and chlorophyll-a trends over time. Basically, the two areas have similar hydrological features, yet they present significant differences in the amount of nutrient inputs: these are in fact higher at the coastal site, which is characterized by a prevalence of surface blooms, while they are lower at the offshore station, which is mainly affected by blooms at intermediate depths. Nonetheless, throughout the whole water column, chlorophyll-a concentrations are only slightly different. Both areas are affected by riverine discharge, though chlorophyll-a concentrations are also driven strongly by the seasonal cycle at the station closer to the coast. Results show that the two stations are not trophically different, although some controlling factors, such as zooplankton grazing in one case and light attenuation in the other, may further regulate the growth of phytoplankton. In both cases no significant trends are detected in either the average chlorophyll-a values or in dispersion of the data, in contrast with significant trends in temperature and salinity.

scholarly journals NW Adriatic Sea variability in relation to chlorophyll-<I>a</I> dynamics in the last 20 years (1986–2005)

2007 ◽  
Vol 4 (1) ◽  
pp. 651-685 ◽  
Author(s):  
L. Tedesco ◽  
G. Socal ◽  
F. Bianchi ◽  
F. Acri ◽  
D. Veneri ◽  
...  
Keyword(s):  
Time Series ◽  
Chlorophyll A ◽  
Adriatic Sea ◽  
Light Attenuation ◽  
Nutrient Inputs ◽  
The North ◽  
First Case ◽  
Western Area ◽  
Offshore Station ◽  
Trends Over Time

Abstract. This paper presents a long-term time series (1986–2005) of hydrological and biogeochemical data, both published and unpublished. Data were collected in the north-western area of the Adriatic Sea, at two stations that are considered hydrodynamically and trophically different. The time series have been statistically and graphically investigated on a monthly scale in order to find not only possible chlorophyll-a trends over time, but also links between the concentrations of chlorophyll-a and the variability in the environment, as well as trophic differences between the two areas. Basically, in both cases the statistical test results show no significant trends in either the average chlorophyll-a values or in dispersion of the data, in contrast with significant trends in temperature and salinity. The two areas have similar hydrological features, yet they present significant differences in the amount of nutrient inputs: these are in fact higher at the coastal site, which is characterized by a prevalence of surface blooms, while they are lower at the offshore station, which is mainly affected by intermediate blooms. Nonetheless, throughout the whole water column, chlorophyll-a concentrations are only slightly different. Both areas are affected by riverine discharge, though in the first case considered chlorophyll-a concentrations are also driven strongly by the seasonal cycle. Finally, the results show that the two stations are not trophically different, although some controlling factors, such as zooplankton grazing in one case and light attenuation in the other, may regulate the growth of phytoplankton.

scholarly journals Comparison of SeaWiFS and MODIS time series of inherent optical properties for the Adriatic Sea

2011 ◽  
Vol 8 (1) ◽  
pp. 85-111 ◽  
Author(s):  
F. Mélin
Keyword(s):  
Time Series ◽  
Optical Properties ◽  
Adriatic Sea ◽  
Total Absorption ◽  
Backscattering Coefficient ◽  
Inherent Optical Properties ◽  
Analytical Algorithm ◽  
Phytoplankton Absorption ◽  
Mean Square Difference ◽  
Particle Backscattering

Abstract. Time series of inherent optical properties (IOPs) derived from SeaWiFS and MODIS are compared for the Adriatic Sea. The IOPs are outputs of the Quasi-Analytical Algorithm and include total absorption a, phytoplankton absorption aph, absorption associated with colored detrital material (CDM) acdm, and particle backscattering coefficient bbp. The average root-mean square difference Δ computed for log-transformed distributions decreases for a from 0.084 at 412 nm to 0.052 at 490 nm, is higher for aph(443) (0.149) than for acdm(443) (0.071), and is approximately 0.165 for bbp at various wavelengths. The SeaWiFS a at 443 and 490 nm, aph at 443 nm and bbp are on average higher than the MODIS counterparts. Statistics show significant variations in space and time. There is an overall increasing gradient for Δ associated with the absorption terms from the open Southern and Central Adriatic to the northwest part of the basin, and a reversed gradient for the particulate backscattering coefficient. Only a(412) and acdm(443) currently represent an unbiased continuity bridging the SeaWiFS and MODIS periods for the Adriatic Sea.

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