A spectral analysis of bottom-induced variation in the colour of Sand Hills lakes, Nebraska, USA

Lodhi, Mahtab A.; Rundquist, Donald C.

doi:10.1080/014311601300175980

Cited by 6 publications

(2 citation statements)

References 23 publications

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“…Since a single 645 nm band is used in the algorithm, light reflected from the shallow bottom could contribute to the satellite signal and lead to algorithm uncertainty [ Lodhi and Rundquist , 2001; Tolk et al , 2000]. Such potential artifacts were estimated in the following way.…”

Section: Discussion: Uncertainty and Future Applicationsmentioning

confidence: 99%

Human induced turbidity changes in Poyang Lake between 2000 and 2010: Observations from MODIS

et al. 2012

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[1] A robust retrieval algorithm to estimate concentrations of total suspended sediments (TSS) in Poyang Lake (the largest freshwater lake in China) was developed using Moderate Resolution Imaging Spectroradiometer (MODIS) medium-resolution (250 m) data from 2000 to 2010 and in situ data collected during two cruise surveys. The algorithm was based on atmospherically corrected surface reflectance at 645 nm, with 1240 nm data serving as a reference for aerosols and a nearest-neighbor method was used to avoid land adjacency effect. The algorithm showed an uncertainty of 30-40% for TSS ranging between 3 and 200 mg L À1. Long-term TSS distribution maps derived from MODIS data and the customized TSS algorithm showed significant variations in both space and time, with low TSS (<10 mg L À1) in wet seasons and much higher TSS (>15-20 mg L À1 ) in dry seasons for the south lake, and generally higher TSS in the north lake. The TSS difference between the north and the south increased significantly after 2002, with mean TSS often reaching >40 mg L À1 in the north. While the TSS seasonality was attributed to the seasonal changes of the lake's circulation, the inter-annual variations were primarily driven by sand dredging activities, regulated by management policies. The case study here provides baseline water quality information for future restoration efforts in Poyang Lake, and more generally, an approach to assess water quality changes in similar water bodies, which have resulted from either climate variability or human activities.

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Section: Discussion: Uncertainty and Future Applicationsmentioning

confidence: 99%

Human induced turbidity changes in Poyang Lake between 2000 and 2010: Observations from MODIS

et al. 2012

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“…In addition, Raman scattering by water molecules was calculated in the simulations. When the depth of the water is larger than three times of the Secchi disk depth, the bottom effect on the remote sensing reflectance could be regarded as insignificant (Lodhi and Rundquist ). Thus, water bottom reflection of Lake Chaohu was ignored (Ma et al ; Ma et al ; Ma et al ).…”

Section: Methodsmentioning

confidence: 99%

An approach to correct the effects of phytoplankton vertical nonuniform distribution on remote sensing reflectance of cyanobacterial bloom waters

Xue

Zhang

et al. 2017

Limnology & Ocean Methods

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Cyanobacterial blooms occur frequently in eutrophic lakes and their potentially harmful effects affected the security of drinking water and food sources, biodiversity, and economic activities, and attracted the attention of general public worldwide. Cyanobacteria could move vertically in the water column by regulating their buoyancy, which leads to the assumption of homogeneous water invalid. Ecolight, based on radiative transfer theory, was applied to examine the effects of vertical nonuniform of chlorophyll a concentrations (Chl a(z)) on remote sensing reflectance spectrum (Rrs(λ)) of optically complex inland waters. Simulations for nonuniform water consisting of three Chl a(z) profile classes, including Gaussian, exponential, and power, were compared with simulations for a reference homogeneous water whose Chl a was identical to average value of the nonuniform case. The near‐surface aggregation of phytoplankton are shown to have significant influence on Rrs(λ) and Chl a inversion algorithms. Variations of ΔRrs(λ) (relative difference of Rrs(λ) between inhomogeneous and homogeneous waters with same average Chl a concentration) mainly depended on the Chl a(z) structure parameters and wavelength. A correction scheme was developed based on the relationships between ΔRrs(λ) and Chl a(z) structure parameters. With knowledge of Chl a(z) profile parameters, Rrs(λ) of inhomogeneous waters can be corrected to the Rrs(λ) of uniform waters with same average Chl a across the water column. Examples of field data from Lake Chaohu illustrated the effects of phytoplankton variation on the near infrared‐to‐red ratio of Rrs and the Rrs correction performance.

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A derivative spectrum algorithm for determination of chlorophyll-a concentration in the Pearl River estuary

Chen

Tang

Xing

et al. 2007

2007 IEEE International Geoscience and Remote Sensing Symposium

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Chlorophyll-a is the pigment presented in living plants or phytoplankton responsible for the photosynthesis, and it is a very important ecological and environmental parameter of waters, not only used for estimation of ocean primary productivity, but also for detection of red tides and for water quality. The chlorophyll-a concentration in coastal waters is generally overestimated from ocean color satellite data with common algorithm. In order to improve the remotely-sensed estimation of chlorophyll-a, many efforts have been made. In this study, six cruises for in situ data collection were conducted in lower reaches of the Pearl River and its estuary, the Lingdingyang, from 2003 to 2006. And the variables such as temperature, salinity, chlorophyll-a, total suspended matters (TSM), nutrients and gelbstoff absorption coefficient (Ag) were collected. The in situ remote sensing reflectance (Rrs) were measured from above waters with an Ocean Optics USB2000 spectrometer, which covers wavelength from 200 to 850 nm with spectral resolution of 0.38 nm. The original in situ Rrs data were processed to EO-1/hyperion bands (at resolution about 10 nm), and the derivative spectra with the different spectral resolutions were analyzed. The statistic analysis shows that the relative coefficient between derivative spectrum and chlorophyll-a is higher than that between original spectrum and chlorophyll-a. The band with highest relative coefficient to chlorophyll-a was employed for development of chlorophyll-a retrieval algorithm. A derivative spectrum algorithm was developed, and then applied to EO-1/hyperion data, which were acquired in December 16, 2006. The distribution image maps of chlorophyll-a concentration retrieved from EO-1/hyperion data were obtained. It shows that the derivative spectral method is an alternative approach for detection of water quality in coastal waters.

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A spectral analysis of bottom-induced variation in the colour of Sand Hills lakes, Nebraska, USA

Cited by 6 publications

References 23 publications

Human induced turbidity changes in Poyang Lake between 2000 and 2010: Observations from MODIS

Human induced turbidity changes in Poyang Lake between 2000 and 2010: Observations from MODIS

An approach to correct the effects of phytoplankton vertical nonuniform distribution on remote sensing reflectance of cyanobacterial bloom waters

A derivative spectrum algorithm for determination of chlorophyll-a concentration in the Pearl River estuary

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