パプアニューギニア大学における合同ワークショップ講演スライド/2013年2月5日 パプアニューギニア沖沿岸湧昇とエルニーニョおよび SPICE国際プロジェクト（パプアニューギニア沖係留系観測など）

1. Takuya HASEGAWA
(JAMSTEC-RIGC, Yokosuka, Japan)
Physical oceanography
Climate system (El Nino/Southern Oscillation: ENSO)
Air-sea interactions in the tropical Pacific
Oceanic and atmospheric variability around PNG and
on-going observations off the New Ireland Island
using R/V Mirai
PNG, 5th Feb 2013

2. General background
Pacific warm water pool
# Pacific warm water pool around PNG (Very high sea surface temperature!)
There are many atmospheric and oceanic phenomena on multi-timescale
e.g., # tropical cyclone (weekly scale),
# Madden-Jullian Oscillation (intraseason-scale variation),
# monsoon (seasonal cycle)
# El Nino-related interannual-scale variations
# decadal-scale change…..
--> Impacts on local, and also global (by teleconnections) weather & climate
# sea temperature, salinity, sea level, currents, winds, rainfall, etc.
Japan
Papua New Guinea

3. 1. Coastal upwelling along New Guinea north coast
2. On-going and near-future
oceanic observations
around New Ireland Island
using R/V Mirai
OUTLINE
1. Coastal
upwelling
2. New Ireland Island
Warm water pool

4. -Background-：Coastal upwelling along Papua New Guinea
Coastal upwelling along Papua New Guinea (New Guinea)
→Generating relatively cool SST
Western equatorial Pacifc
Existence of New Guinea coastal
upwelling
（e.g., Lukas1988; Ueki et al. 2003)
Purpose of the present study：
# To check existence of New Guinea coastal upwelling before onset of El Nino
# To explore a mechanism of SST cooling related to New Guinea coastal
upwelling
New
Guin
ea
Pacific warm pool
Westerly wind
Bismarck Sea
1. Coastal
upwelling
1. Coastal upwelling along
New Guinea north coast
TRIOTN buoy
CTD

5. Background for coastal upwelling along north coast of New Guinea
Existence of coastal upwelling
along New Guinea
（e.g., Lukas1988; Ueki et al. 2003)
New Guinea
Island
Eastward shift of
warm pool
Westerly wind
Bismarck Sea
Expected process (hypothesis) starting strong coastal upwelling along PNG:
Occurrence of anomalously strong coastal upwelling
→ Generates relatively cool sea surface temperature (SST)
→ Generates positive SST gradient in the warm pool region
→ Can contributes to enhancement of westerly wind
(e.g., Lindzen and Nigram 1987; Eisenman et al. 2005; Gebbie et al. 2007)
→ Can trogger astward moving of warm pool and resultant El Nino onset
(e.g., McPhaden 2004)
Onset of
El Nino

6. Purpose of the present study：
# To check existence of coastal upwelling in the Bismarck Sea
before onset of El Nino
# To explore a mechanism of SST cooling related to New Guinea coastal upwelling
# To check a relationship between SST cooling and westerly wind

7. Obs: Upper ocean temperature structure observed by R/V Kaiyo
2.7˚S EQ
CTD stations
28 degC
Coastal upwelling with relatively cool SST along north coast
prior to onset of 2002/03 El Nino
Shallower near the coast
Latitude-depth diagram of CTD-observed temperature
80m depth
20m depth
CTD-observation of the R/V Kaiyo
for 21-23 December 2001
(Prior to onset of 2002/03 El Nino)
Snapshot of daily SST on 22 December 2001
Shows coastal upwelling Cool sea surface
temperatures( SSTs)
distribute along coast
Hasegawa et al. 2009 JO
Depth(m)
Latitude (deg)
TMI-satellite
SST
(22 Dec. 2001)

8. SST from
TMI satellite
20 Dec 2001
10 Jan 2002
30 Dec 2001
Relatively cool SST area:
Northeastward extension from the coast toward the equator
(degC)
Obs: Extension of the cold SST area from the coast found in TMI-SST
Hasegawa et al. 2009 JO

9. Heat budget analysis using TRITON buoy
Using four TRITON moored buoy at EQ-147E near PNG
# Buoy data ->MLT, horizontal heat adv., net surface heat flux
# Residual: Vertical heat adv., entrainment cooling, diffusion
# Daily data; tide-killer & 7-day running mean filteredDec 2001
Mixed Layer Temp.
PNG coastal upwelling period
Large contribution of eastward zonal heat advection to cooling,
as compared to the net surface heat flux and other factors
Effect from zonal heat adv.
(degC)
R
y
T
v
x
T
u
hc
Q
t
T
p
surface
+
∂
∂
−
∂
∂
−=
∂
∂
0ρ
TRITON buoy (EQ-147E)
Temporal integration
of each term of heat budget equation
Mixed Layer Temp.
(degC)
Hasegawa
et al.
2009 JO

10. Numerical simulation:
high-resolution Ocean General Circulation Model (OGCM) hindcast
using a super computer “Earth Simulator” of JAMSTEC-ESC
Complicated surface currents:
related to the coastal upwelling
and extension of the cool SST area
Hasegawa et al. 2010 (OD)
Hasegawa et al. 2011 (JPO)
Modeled surface currents
averaged 20 Dec2001 – 20 Jan 2002
(upwelling period)

11. Positive zonal difference in SST
(Positive zonal gradient of SST)
Westerlywind
Large positive zonal gradient of SST accompanies
strong westerly wind, which can trigger the El Nino
onset via eastward movement of warm water pool
Positive SST zonal gradient
→Negative SLP zonal gradient
→Enhancement of westerly surface wind
(e.g., Kessler & Kleeman 2000)
Zonalsurfacewindaveragedover
westernequatorialPacific(m/s:140-160E)
Warm
Zonal difference in SST in the western EQ Pacific (degC)
(150-160E minus 140-150E)
Cool
Westerly
Relationship between SST cooling and westerly surface wind
(TMI-SST & QuikSCAT surface wind)
Hasegawa et al. 2009 JO

12. onset of
El Nino
Summary and discussion for coastal upwelling along New Guinea
eastward shift of
warm pool
zonal heat advectionSST cooling
Observational and model experiments suggest potential impact
of small-scale oceanic variation such as coastal upwelling on
large scale climate variations
New Guinea
positive zonal gradient of SST
& strong westerly surface wind
Suggestion; Potential impact of small-scale oceanic variations on
large-scale climate variations such as El Nino.
Also, may be related to fishery, coastal environment, rainfall in PNG

13. -Background-：Coastal upwelling along Papua New Guinea
Coastal upwelling along Papua New Guinea (New Guinea)
→Generating relatively cool SST
Western equatorial Pacifc
Existence of New Guinea coastal
upwelling
（e.g., Lukas1988; Ueki et al. 2003)
Purpose of the present study：
# To check existence of New Guinea coastal upwelling before onset of El Nino
# To explore a mechanism of SST cooling related to New Guinea coastal
upwelling
New
Guin
ea
Pacific warm pool
Westerly wind
Bismarck Sea
2. On-going and near-future
observation around New Ireland
Island using R/V Mirai
2. New Ireland Island

14. To explore western boundary currents around New Guinea
and its impact on warm pool changes
French
&
USA
subsurface
ADCP
moorings
JAMSTEC
subsurface
ADCP
moorings
TRITON
buoys
_
New
Guinea
Subsurface
ADCP
moorings
by
Japan,
USA,
and
France:
To
explore
ouIlows
from
Solomon
Sea
to
Bismarck
Sea
and
western
Pacific
JAMSTEC
moorings:
focus
on
New
Ireland
Coastal
Undercurrent
(NICU),
observing
current
velocity
of
NICU
by
the
moorings
Plus:
various
observaQons
for
oceanic
temperature
and
salinity
Total
target
of
CLIVAR-­‐SPICE
[Sv]
Target:
Bismarck
Sea
Solomon
Sea
CooperaQon
with
moorings
by
France
and
USA,
based
on
CLIVAR-­‐SPICE
internaQonal
project
(MoorSPICE)

15. Recent
observaQon
by
R/V
Mirai
(MR12-­‐03
cruise
for
Jul-­‐Aug
2012)

16. Recent
R/V
Mirai
cruise
(MR12-­‐03
cruise)
MR12-­‐03:
During
July-­‐August
2012:
#
Deployment
of
two
ADCPs
(AcousQc
Doppler
Current
Profilers)
subsurface
moorings
#
CTD/Lowered
ADCP
(LADCP)
observaQon
near
mooring
points
(Temp
&
Salinity
profile/current
velocity
profile)
#
Launch
of
one
Argo
float
(Temp
&
salinity
profile)
#
Along
track
conQnuous
observaQons:
XCTD
(Temp
&
salinity
profile)
Shipboard
ADCP
(SADCP:
current
velocity),
etc.

17. Design
of
the
JAMSTEC
subsurface
ADCP
moorings
Sea surface
CTD sensor (605-685m depth)
Anchor
Releaser (double)
~3500 m depth
Upward ADCP sensor (600-680m depth)
Top float (260-400m depth)
with upward ADCP (current velocity) &
CTD (temperature and salinity) sensors
~
~
Current velocity
observed by ADCP
(50m~650m)
NICU
Two
moorings
for
NICU
Sea bottom
NICU
Deployment of the mooring
during MR12-03 cruise

18. Deployment of the subsurface ADCP mooring from R/V Mirai

19. Other observations related to ADCP mooring: Argo float, etc.
# Argo float is one kind of unmanned drifter, to observe automatically temperature and salinity
from roughly 2000m to surface.
# One Argo float was launched very near ADCP-mooring point during MR12-03 cruise.
NEMO-type float launched
during MR12-03 cruise
CTD: Temperature,
salinity
and Pressure
sensor

20. Plan
for
next
observaQon
by
R/V
Mirai
(MR14-­‐02
cruise
for
Feb-­‐March
2014)

21. MR14-­‐02:
During
February-­‐March
2014:
#
Recovery
of
the
two
ADCP
subsurface
moorings
#
CTD/LADCP
observaQon
near
mooring
points
(Temp
&
salinity
profile/current
velocity
profile)
#
Along
track
conQnuous
observaQons:
XCTD
and/or
CTD
(Temp
&
salinity
profile)
SADCP
(current
velocity),
etc.
(if
possible,
launch
of
one
Argo
float
(Temp
&
salinity
profile)
)
Present
rough
plan
for
next
R/V
Mirai
cruise
(MR14-­‐02
cruise)
*
Details
would
be
changed
130˚E
130˚E
140˚E
140˚E
150˚E
150˚E
160˚E
160˚E
170˚E
170˚E
10˚S 10
0˚ 0˚
10˚N 10
20˚N 20
30˚N 30
40˚N 40
130˚E
130˚E
140˚E
140˚E
150˚E
150˚E
160˚E
160˚E
170˚E
170˚E
10˚S 10
0˚ 0˚
10˚N 10
20˚N 20
30˚N 30
40˚N 40
130˚E
130˚E
140˚E
140˚E
150˚E
150˚E
160˚E
160˚E
170˚E
170˚E
10˚S 10
0˚ 0˚
10˚N 10
20˚N 20
30˚N 30
40˚N 40
Sekinehama
Hachinohe
Koror

22. R/V Mirai MR12-03 Cruise (Jul-Aug 2013):
Two subsurface ADCP moorings were deployed off New Ireland Island,
to observe mainly current velocity from 50m to 650m.
(Cooperation with CLIVAR-SPICE mooring project: MoorSPICE)
In addition, Argo floats was launched near mooring point.
Along cruise track, temperature and salinity were observed by XCTD (0-1000m),
and current velocity were observed by SADCP and LADCP.
Now, we are going to the next cruise observation of
R/V Mirai (MR14-02 cruise: Feb-March 2014)
These observations will contribute to deeper understanding of mechanism of
warm water supply to warm pool through NICU, which can be related to weather
and climate changes in PNG and other many countries.
Summary for R/V Mirai observations

23. My published papers for coastal upwelling study:
Hasegawa, T., K. Ando, K. Mizuno, and R. Lukas (2009):
“Coastal upwelling along north coast of Papua New Guinea and SST cooling over Pacific warm pool:
A case study of 2002/03 El Nino”, Journal of Oceanography, vol. 65, 817-833.
Hasegawa, T., K. Ando, K. Mizuno, R. Lukas, B. Taguchi, and H. Sasaki (2010):
“Coastal upwelling along the north coast of Papua New Guinea and El Nino events during 1981-2005”,
Ocean Dynamics, vol. 60, 1255-1269.
Hasegawa, T., K. Ando, and H. Sasaki (2011):
“Cold water flow and upper-ocean currents in the Bismarck Sea from December 2001 to January 2002”,
Journal of Physical Oceanography, vol. 41, 827-834.