Modeling of acidification in marginal seas
Yasumasa Miyazawa*1, Miho Ishizu1, Tomohiko Tsunoda2
1 JAMSTEC 2 Sasakawa Peace Foundation

Ocean acidification is now observed in open ocean around
Japan (Ishii et al. 2011).
Biogeochemical processes associated with the acidification
are more complicated and heterogeneous in coastal ocean(Kosugi et al. 2016). For example, the amplitude of seasonalvariations of Aragonite Omega exceeds 3 in Tokyo Bay(Yamamoto-Kawai et al. 2015; cf. 0.5 in Ishii et al. 2011).
To elucidate the acidification trend/variation in shelf and coastal
ocean seas around Japan, we are developing ocean acidification
modeling focusing on nowcasting of the acidification processes
around Japan.

‘Marine Crisis Watch’ project

Our research is a part of the ‘Marine Crisis Watch’ project
promoted by Sasakawa Peace Foundation (Ocean Policy
Research Institute), aiming at constructing a web-based
information infrastructure for enhancement of public
understanding on-going ocean acidification in the western
North Pacific.

Expecting research period is from FY2016 to FY2019, 4 years.
Our group of JAMSTEC is originally developing dataassimilative ocean current forecasting models, and thus
we are planning coupling the ocean forecasting with the ocean
acidification modeling.
Prior to model development, we have examined actual PH
variations recorded in a public water measurement data base.

Water quality measurements doneby local prefectures
Total

Coastal seas

The archive includes
the data obtained inlakes, rivers, coastal
sea regions.
8497 points

1987

2164 points

1987

8817 points

20092127 points

2009

We have analyzed
the data obtained incoastal sea regions.

Acidification/ alkalization trends in coastal water
regions
二の倉地先海域 Miyagi

Y=-0.0202x+47.9

風蓮湖 Hokkaido

Y=0.0139x-20.391

Y=-0.0128x+33.9

Y=0.0118x-15.146

東京湾（５）Tokyo

富山新港海域 Toyama

Y=-0.0138x+35.1

Y=-0.015x+38.4

平良港Okinawa

Y=0.0114x-15.675

Y=0.018x-29.456
清水港 Shizuoka

Y=-0.0111x+30.16

Y=-0.0111x+30.59

Y=0.0126x-17.155
Y=0.0121x-15.723

Distribution of slopes of linear
regression line (y=ax+b) Comparable trend
Slope (a) < 0.0 ： trend of acidificationof the acidificationin open oceans

1496 points

Average of ΔpH = 0.0015
σ = 0.0075

https://public.wmo.int/en/resources/bulletin/monitoringocean-carbon-and-ocean-acidification-0

Decrease in pH
ESTOC : 0.0017±0.0005 yr-1
(mean±1σ)
BATS
0.0017±0.0001 yr-1 in winter
HOT : 0.0019±0.0005 yr-1

Slopes of regression line
Decrease of pH= -0.0015±0.0075 yr-1

JMA along 135E
0.0018±0.0021 yr-1 in winter0.0008±0.0019 yr-1 in summer

Apparent Acidification/ alkalization
Dominance of acidification points despite ofpoints
complicated trend distribution

Acidification slope ΔPH < 0Alkalization

332 points

87 points

slope ΔPH > 0ΔpH≦-0.01

ΔpH≧0.01-0.01≦ΔpH<-0.008-0.008≦ΔpH<-0.006-0.006≦ΔpH<-0.004-0.004≦ΔpH<-0.002-0.002≦ΔpH<0.00.008≧ΔpH＞0.01
0.006≧ΔpH>0.008
0.008≧ΔpH>0.006
0.002≧ΔpH>0.004
0.0≧ΔpH>0.02

Statistically significant (p>0.05)
acidification/alkalization points
Relatively strong signals of the acidification points?
Acidification slope ΔPH < 0 Alkalization slope ΔPH > 064points

11 points

We need to investigate temporal/spatial dependence of theocean acidification around Japan coastal ocean

Possible coupling with ocean forecasting
Our group of JAMSTEC is operating ocean forecasting models
Satellite data
Shipdata
ARGO floats
Super computers
http://www.jamstec.go.jp/jcope/
They would be used for investigation of the on-going acidificationin terms of ocean currents/eddies effects

Numerical ocean forecasting
JCOPE-T: Hourly/3km resolution
Ocean current and eddy activity isquite evident around Japan
Possible relations between the oceancurrent and acidification

ocean currents/eddies
represented by vorticity

Zoom-up view

Marine carbon cycle affected by ocean current
Atmosphere
air-seaexchangepHΩ

(Hofmann et al. 2011)

DissolvedInorganic
CarbonClimatology

coastalprocesses
Diagnosis
Alkalinity

Calcination(Month)

NPZD

(Day)

ocean current variability
CaCO3

Summary and plan
We have detected strong contrast of the acidification/alkalization
among coastal stations in Japan
Some of them might be attributed to very local processes thatnever be resolved by our ocean forecasting models; however,
we will try to find some points that could be affected by the ocean
current and eddy activity as well as ones affected by some other
resolved processes including large scale fresh
water flux from the land, etc.
Nowcasting based on coupling of data-assimilative ocean current
models with eco-carbon cycle models together with detailed
observation data analysis would be usefulfor such investigation
Our research may contribute to the global Marine Biodiversity
Observation Network (MBON).

Ocean acidification in open ocean south
Distribution of yearly Surface pH inof Japan
winter along 137 E

Yearly averaged CO2 between 7
and 33E along 137 E

Yearly surface CO2 in winter along 137E
and 165 E