Correlation of Asian dust with chlorophyll and primary productivity in the coastal seas of China during the period from 1998 to 2008

Tan, Shuxin; Shi, Guangyu; Shi, Jianghong; Gao, Huiwang; Yao, Xiaohong

doi:10.1029/2010jg001456

Cited by 81 publications

(66 citation statements)

References 33 publications

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“…In addition, the annual dust input to the entire ECS is estimated to be 17 Mt, which appears to be a significant source of sediments and dissolved Fe compared with riverine discharge (Hsu et al, 2009). Tan et al (2011) also found that chl a and primary production increased and eventually became a bloom 1-21 days after the occurrence of dust storms in the southern YS. It would be worth investigating the longterm trends of dust input when such data become available in the future.…”

Section: Nutrient Supply In Region Bmentioning

confidence: 95%

Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

et al. 2013

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Abstract. The eastern China seas are some of the largest marginal seas in the world, where high primary productivity and phytoplankton blooms are often observed. However, little is known about their systematic variation of phytoplankton blooms on large spatial and long temporal scales due to the difficulty of monitoring bloom events by field measurement. In this study, we investigated the seasonal and interannual variability and long-term changes in phytoplankton blooms in the eastern China seas using a 14 yr (1998–2011) time series of satellite ocean colour data. To ensure a proper satellite dataset to figure out the bloom events, we validated and corrected the satellite-derived chlorophyll concentration (chl a) using extensive in situ datasets from two large cruises. The correlation coefficients between the satellite retrieval data and the in situ chl a on the logarithmic scale were 0.85 and 0.72 for the SeaWiFS and Aqua/MODIS data, respectively. Although satellites generally overestimate the chl a, especially in highly turbid waters, both the in situ and satellite data show that the overestimation of satellite-derived chl a has an upper limit value (10 μg L−1), which can be used as a threshold for the identification of phytoplankton blooms to avoid the false blooms resulting from turbid waters. Taking 10 μg L−1 as the threshold, we present the spatial-temporal variability of phytoplankton blooms in the eastern China seas over the past 14 yr. Most blooms occur in the Changjiang Estuary and along the coasts of Zhejiang, with a maximal frequency of 20% (about 73 days per year). The coasts of the northern Yellow Sea and the Bohai Sea also have high-frequency blooms (up to 20%). The blooms show significant seasonal variation, with most occurring in spring (April–June) and summer (July–September). The study also revealed a doubling in bloom intensity in the Yellow Sea and Bohai Sea during the past 14 yr. The nutrient supply in the eastern China seas might be a major controlling factor in bloom variation. The time series in situ nutrient datasets show that both the nitrate and phosphate concentrations increased more than twofold between 1998 and 2005 in the Yellow Sea. This might be the reason for the doubling of the bloom intensity index in the Yellow Sea and Bohai Sea. In contrast, there has been no significant long-term increase or decrease in the Changjiang Estuary, which might be regulated by the Changjiang River discharge. These results offer a foundation for the study of the influence of phytoplankton blooms on the carbon flux estimation and biogeochemical processes in the eastern China seas.

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Section: Nutrient Supply In Region Bmentioning

confidence: 95%

Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

et al. 2013

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“…A suitable chlorophyll index can offer useful information for estimating the gross productivity of a terrestrial ecosystem (Nave et al, 2011) and even for understanding dust storm events (Tan et al, 2011). In order to address the effects of global climate changes, it is necessary to continuously update the prediction of forest carbon sequestration and the net primary productivity of terrestrial ecosystem.…”

Section: Indexmentioning

confidence: 99%

A novel reflectance-based model for evaluating chlorophyll concentrations of fresh and water-stressed leaves

et al. 2015

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Abstract. Water deficits can cause chlorophyll degradation which decreases the total concentration of chlorophyll a and b (Chls). Few studies have investigated the effectiveness of spectral indices under water-stressed conditions. Chlorophyll meters have been extensively used for a wide variety of leaf chlorophyll and nitrogen estimations. Since a chlorophyll meter works by sensing leaves absorptance and transmittance, the reading of chlorophyll concentration will be affected by changes in transmittance as if there were a water deficit in the leaves. The overall objective of this paper was to develop a novel and reliable reflectance-based model for estimating Chls of fresh and water-stressed leaves using the reflectance at the absorption bands of chlorophyll a and b and the red edge spectrum.Three independent experiments were designed to collect data from three leaf sample sets for the construction and validation of Chls estimation models. First, a reflectance experiment was conducted to collect foliar Chls and reflectance of leaves with varying water stress using the ASD FieldSpec spectroradiometer. Second, a chlorophyll meter (SPAD-502) experiment was carried out to collect foliar Chls and meter readings. These two data sets were separately used for developing reflectance-based or absorptance-based Chls estimation models using linear and nonlinear regression analysis. Suitable models were suggested mainly based on the coefficient of determination (R 2 ). Finally, an experiment was conducted to collect the third data set for the validation of Chls models using the root mean squared error (RMSE) and the mean absolute error (MAE). In all of the experiments, the observations (real values) of the foliar Chls were extracted from acetone solution and determined by using a Hitachi U-2000 spectrophotometer.The spectral indices in the form of reflectance ratio/difference/slope derived from the Chl b absorption bands (ρ 645 and ρ 455 ) provided Chls estimates with RMSE around 0.40-0.55 mg g −1 for both fresh and water-stressed samples. We improved Chls prediction accuracy by incorporating the reflectance at red edge position (ρ REP ) in regression models. An effective chlorophyll indicator with the form of (ρ 645 -ρ 455 ) / ρ REP proved to be the most accurate and stable predictor for foliar Chls concentration. This model was derived with an R 2 of 0.90 (P < 0.01) from the training samples and evaluated with RMSE 0.35 and 0.38 mg g −1 for the validation samples of fresh and water-stressed leaves, respectively. The average prediction error was within 14 % of the mean absolute error.

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“…4(a). High aerosol loading and water reflectance conditions are occurred due to the transportation from inland pollutant as a result of increase of oceanic substances or primary productivity (Tan et al, 2011). The retrieved Chl and sediment concentrations are mostly higher than those of other sites with averaged 25 Chl and S s up to 2.16 mg m -3 and 1.75 g m -3 in this study, since the location of this site is typically viewed as high turbid waters.…”

Section: Using Satellite Measurements Out Of Sun Glintmentioning

confidence: 72%

Simultaneous determination of aerosol optical thickness and water leaving radiance from multispectral measurements in coastal waters

Shi¹,

Nakajima²

2017

Preprint

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Abstract. Retrieval of aerosol optical properties and water leaving radiance over ocean is changeling since the latter mostly 10 accounts for ~10% of satellite observed signal and can be easily contaminated by the atmospheric scattering. Such an effort would be more difficulty in turbid coastal waters due to the existence of optically complex oceanic substances or high aerosol loading. In an effort to solve such problems, we present an optimization approach for the simultaneous determination of aerosol optical thickness (AOT) and normalized water leaving radiance (nL w ) from multi-spectral measurements. In this algorithm, a coupled atmosphere-ocean radiative transfer model combined with a comprehensive bio-optical oceanic module 15 is used to jointly simulate the satellite observed reflectance at the top of atmosphere and water leaving radiance just above the ocean surface. Then a full-physical nonlinear optimization method is adopted to retrieve AOT and nL w in one step. The algorithm is validated using Aerosol Robotic Network Ocean Color (AERONET-OC) products selected from eight OC sites distributed over different waters, consisting of observation cases covered both in and out of sun glint from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. Results show a good consistency between retrieved and in situ 20 measurements in each site. It is demonstrated that more accurate AOT are determined based on the simultaneous retrieval method, particularly in shorter wavelengths and sun glint conditions, where the averaged percentage difference (APD) of retrieved AOT generally reduce by approximate 10% in visible bands compared with those derived from the standard atmospheric correction (AC) scheme. It is caused that all the spectral measurements can be used jointly to increase the information content in the inversion of AOT and the wind speed is also simultaneously retrieved to compensate the specular 25 reflectance error estimated from the rough ocean surface model. For the retrieval of nL w , over atmospheric correction can be avoided to have a significant improvement for the inversion of nL w at 412 nm. Furthermore, generally better estimates of band ratios of nL w (443)/nL w (554) and nL w (488)/nL w (554), which are employed in the inversion of chlorophyll a concentration (Chl), are obtained using simultaneous retrieval approach with less root mean square errors and relative differences than those derived from the standard AC approach in comparison to the AERONET-OC products, as a result that 30 the APD value of retrieved Chl decreases by about 5%. On the other hand, the standard AC scheme yields a more accurate retrieval of nL w at 488 nm, prompting a further optimization of oceanic bio-optical module of current model. Atmos. Chem. Phys. Discuss., https://doi

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Correlation of Asian dust with chlorophyll and primary productivity in the coastal seas of China during the period from 1998 to 2008

Cited by 81 publications

References 33 publications

Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

Satellite views of the seasonal and interannual variability of phytoplankton blooms in the eastern China seas over the past 14 yr (1998–2011)

A novel reflectance-based model for evaluating chlorophyll concentrations of fresh and water-stressed leaves

Simultaneous determination of aerosol optical thickness and water leaving radiance from multispectral measurements in coastal waters

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