SeaWiFS/MODIS examples on coastal/inland water quality assessment

Bloom monitoring

Cyanobacteria (Microcystis aeruginosa)

Cyanobacteria (Trichodesmium erythraeum)

Diatom (Pseudo nitzschia)Coccolithophore

RGB

26oN

25oN

82oW83oW

FLH

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2

MODIS FLH differentiates Chl from CDOM, otherwise it is nortoriously difficult to separate the two

Bloom monitoring

From Hu et al. (2005)

Karenia brevis bloom monitoringHigh MODIS FLH and low backscattering efficiency => K. brevis bloom

A bloom can be identified from MODIS FLH. Then, a backscattering efficiency test will tell whether it is a toxic K. brevis bloom or non-toxic bloom. From Cannizzaro et al. (2008) and Hu et al. (2011)

MODIS detects Trichodesmium blooms in optically complex waters

WFS

5/22/2004In situ Rrs of a Tricho bloom

MODIS ocean bandsMODIS land bands

The spectral curvatures (high-low-high-low-high) are due to PUB and PEB pigments in Trichodesmium.These features will not be detected without combining MODIS ocean and land bands.

0.000

0.005

0.010

0.015

Rrs

(sr-1

)

400 500 600 800 900700 (nm)

Figure from Hu et al. (2010)

MERIS does not have enough bands in the circles spectral region

MODIS is equipped with the right bands (by coincidence!) to recognize the unique pigments in Tricho. colony

Long-term trend related to local aquaculture. Floating Algae Index was used to quantify Ulva prolifera bloom coverage

From Hu and He (2008) and Hu et al. (2010)

Olympic SailingQingdao

Macroalgae Blooms Long-term Trend, Yellow Sea

Seasonal Variations of Water Clarity (SDD) in Tampa Bay (SeaWiFS 1998-2005)

Lee et al. (2005) Kd algorithm was used to derive SDD. From Chen et al. (2007a, RSE)

Seasonal Variations of Water Turbidity in Tampa Bay (MODIS 2003-2005)

MODIS 250-m data at 645-nm were used to derive turbidity. From Chen et al. (2007b, RSE)

MODIS nLw from SWIR atmospheric correctionSeasonal patterns of nLw(443) in Taihu Lake, Wang et al. (2011, RSE)

Taihu Lake Cyanobacteria Blooms Long-term Trend

Bloom charaterized using a floating algae index (Hu et al. 2010)

Human-induced turbidity changes in Poyang Lake, China

From Feng et al. (2012)

MODIS 250-m data revealed 2000-2010 trend

Oil Spill Assessment using MODIS

From Hu et al. (2011)

MODIS 250-m sun glint imagery reveals oil slicks