Assessment of marine and coastal

eutrophication using remotely sensed chlorophyll-a

concentration

Genki Terauchi1, Elígio de Raús Maúre1, and Joji Ishizaka2

1 Northwest Pacific Region Environmental Cooperation Center /NOWPAP CEARAC

2 Institute for Space-Earth Environmental Research,

Division for Land-Ocean Ecosystem Research, Nagoya University

Regional Seas Programme and NOWPAP

Regional Seas Programme (RSP)• Launched in 1974 by UNEP to address the accelerating degradation of the world’s oceans and coastal areas.

• RSP covers 18 regions around the world.

Northwest Pacific Action Plan

(NOWPAP)• Adopted in 1994

• 4 regional activity centers are set up in China, Japan, Korea and Russia

• Geographical scopeLatitude 33 - 52ON Longitude 121 – 143E

NOWPAP region

NOWPAP CEARAC(Special Monitoring and Coastal Environmental Assessment Regional

Activity Center of NOWPAP)

Missions

• Assessment of the state of the marine, coastal and associated freshwater environments

• Development of tools for environmental assessment using remote sensing techniques

Activities

• Harmful Algal Blooms

• Remote Sensing of Marine Environment

• Assessment of Eutrophication

• Marine Litters

• Marine Biodiversity

Consequences of eutrophication and its indicator development for

SDG 14.1.1 in the Northwest Pacific Region

Red tide

Green tide

Giant jelly fish

Hypoxia

Imai and Hori 2006

Wei et al 2007

Liu et al., 2010

Dong et al., 2010

Index of Coastal Eutrophication

(ICEP)

NOWPAP common procedure for

eutrophication assessment

Procedures for assessment of

eutrophication status including

evaluation of land-based sources

for nutrients for the NOWPAP

region (refined in 2013)

Use of selected parameters

including the remotely sensed

data is proposed as a

screening tool

The Common Procedures

(as of Aug 2013)

Assessment of eutrophication

by the NOWPAP Common Procedure

NOWPAP CEARAC (2009, 2014) Terauchi et al. (2014, 2018)

Level of Chl-a for

eutrophication assessment

proposed

by Bricker et al. (2003)

Hypereutrophic (>60ug l−1)

High (>20, ≤60ug l−1)

Medium (>5, ≤20ug l−1)

Low (>0 and ≤5ug l−1)

Concentration Level Trend

Help plan immediate mitigation intervention action

Help plan preventive management action

Chl-a level of 5ug l-1 is used as value for early warning against recent 3-year mean

Annual maximum value in monthly mean

NASA Standard

for case 1 water

YOC and NASA Standard mix

for case 2 water

(Locally tuned algorithm)

Satellite Chl-a used to assess

eutrophication in the NOWPAP region• Satellite Sensors

SeaWiFS (1998-2004)

MODIS-Aqua (2002-2016)

• Dataset and algorithms

Reprocessing 2014

NASA Standard and YOC

YOC Algorithm and pixel to pixel conversion of MODIS

Rrs band ratios

SeaWiFS

Rrs(443)/Rrs(555) = A

Rrs(412)/Rrs(490) = B

RoS

=Rrs(443)

oS

Rrs(555)oS

æ

èçç

ö

ø÷÷

Rrs(412)oS

Rrs(490)oS

æ

èçç

ö

ø÷÷

-0.463

A B

CHLoS

=10-0.166-2.158Log

10(RoS

)+9.345Log210

(RoS

)( )

MODIS Rrs

Rrs(443)/Rrs(547) = A'

Rrs(412)/Rrs(488) = B'

Jan

1998

MODIS (Aqua)

Jun

2002

Dec

2004

SeaWiFS

Dec

2016

Pixel to pixel

Comparison

Empirical algorithm developed by Yellow Sea Large Marine Ecosystem Ocean Color Work Group

YOC Algorithm (Siswanto et al., 2011)

Angles of the regression lines (left) and intercept (right)

SeaWiFS Rrs(555) vs MODIS-A Rrs(547)

42O N

36O N

30O N

120O E 128O E

B B’

SeaWiFS Rrs(412/490) vs MODIS-A Rrs(412/488)

A A’

SeaWiFS Rrs(443/555) vs MODIS-A Rrs(443/547)

Comparison of Rrs ratios and Rrs between

SeaWiFS and MODIS-A

Switching OC algorithms

NASA STD 100%

YOC 100%

0.008163

0.013605

Rrs555

Terauchi et al. 2018

Assessment of eutrophication in the Northwest

Pacific Region based on the NEAT

0.1 1 10 64 mg m-3

3 years (2013-2015) mean

-0.3 0 0.3 (mg m-

3/year)

Interannual trend of annual maximum

from 1998 to 2015

Terauchi et al. (2018)HD HN HI

LD LN LI

NASA Standard

for case 1 water

YOC and NASA Standard

mix for Case 2 water

Development of

Global Eutrophication Inspector

based on the NEAT

HD HN HI

LD LN LI

Embedding the NEAT algorithm

in Google Earth Engine

Use of SGLI of the GCOM-Mission

will enhance the applicability of satellite Chl-a

in eutrophication assessment in coastal zone

Chlorophyll-a concentration on

May 23, 2018 observed by SGLI

on board GCOM-C mission.

Image provided by Dr. Hiroshi

Murakami, JAXA

Summary• 1. The NEAT method can help develop indicator for the index of coastal

eutrophication under the SDG 14.1.1 by using both concentration

level and trend of remotely sensed Chl-a.

• 2. Application of the NEAT method in a global scale is in progress and

almost ready for operational use.

• 3. Use of higher resolution OC sensors such as JAXA SGLI is planned to

better detect eutrophication in estuary and enclosed bays.