![Page 1: Evaluation of sea surface salinity observed by Aquarius · Aquarius SSS (beam1, 2, 3) 1) V2.3.1 : NASA/JPL PO.DAAC 2) CAP V2.3.1 : NASA/JPL, Dr. Simon Yueh 3) RSS V3 : Remote Sensing](https://reader035.vdocument.in/reader035/viewer/2022070723/5f0200807e708231d4021781/html5/thumbnails/1.jpg)
Evaluation of sea surface salinity
observed by Aquarius
Hiroto Abe, Naoto Ebuchi
(Hokkaido University, Japan)
1
8th Aquarius/SAC-D
Science Team Meeting
(November 13th, 2013)
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Objective of this study(1/1)
Validate SSS observed by Aquarius using
various salinity data including Argo observation.
2
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Data (1/2) - Level 2 -
Satellite salinity
Aquarius SSS (beam1, 2, 3)
1) V2.3.1 : NASA/JPL PO.DAAC
2) CAP V2.3.1 : NASA/JPL, Dr. Simon Yueh
3) RSS V3 : Remote Sensing Systems
In situ salinity
1) Argo salinity : Global Data Assembly Center,
real-time mode data
2) TAO/TRITON, PIRATA, RAMA buoys
3
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Data (2/2) - Level 3 -
Satellite salinity
Aquarius Level 3 SSS (V1.3, V2.2, V2.3.1, CAP V2.3.1)
NASA/JPL PO.DAAC
Salinity data
1) JAMSTEC Argo optimal interpolation system : MOAA/GPV
(Argo salinities are interpolated based on World Ocean Atlas 2001)
2) JMA data assimilation system : MOVE/MRI.COM
(In-situ and satellite altimeter data are assimilated into it)
4
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Comparison with in situ data (1/3)
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Aquarius (Level2) v.s. Argo float
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rms difference =
0.44 psu
6
Comparison with in situ data (1/3)
1) wind speed < 15m/s
2) Argo temperature > 5C)
3) Argo depth < 12.5 dbar
4) rad_land_frac < 0.0005
5) rad_ice_frac < 0.0005
Period : 25 Aug 2011 – 31 Oct 2013
Matchup condition : 200 km, 12 h
Argo salinity (psu)
Aquarius S
SS
(psu)
V2.3.1, beam1
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Comparison with in situ data (2/3)
Rms difference =
0.44 0.55 0.44
Aquarius S
SS
(psu)
Argo salinity (psu)
V2.3.1 CAP V2.3.1 RSS V3
beam1
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Comparison with in situ data (3/3)
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Aquarius (Level2) v.s. moored buoys
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Comparison with in situ data (3/3)
V2.3.1 CAP V2.3.1 RSS V3
beam1
Aquarius S
SS
(psu)
buoy salinity (psu)
Rms difference =
0.43 0.49 0.47
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V2.3.1 CAP V2.3.1 RSS V3
-0.8 +0.8 0.0
Sep. 2011
Mar. 2012
psu
Ascending minus descending seasonality (1/2)
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CAP V2.3.1
RSS V3
60N
60S
0
The bias is small
for the CAP product.
Ascending minus descending seasonality (2/2)
J M M J S N N S
2011 2012
+0.4
-0.4
0.0
(psu)
V2.3.1 la
titu
de
J M
2013
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Residual analysis (1/6) -SST-
12
Argo temperature(degC)
resid
ual (p
su)
2
-2 0
30 20 10 0
V2.3.1
RSS V3
CAP V2.3.1
residual = AQ - Argo
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Residual analysis (2/6) -SST-
13
bias stddev 1.0
-1.0
0.0
0
1.0
10 20 30 Argo temperature(degC)
The stddev is large under low SST condition.
2.0
0.0
Argo temperature(degC) 0 10 20 30
V2.3.1 CAP RSS V2.3.1 CAP RSS
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Residual analysis (3/6) -wind speed-
14
scatt. wind speed (m/s)
2
-2 0
20 10 0
V2.3.1
RSS V3
CAP V2.3.1
residual = AQ - Argo
resid
ual (p
su)
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Residual analysis (3/6) -wind speed-
15
bias 1.0
-1.0
0.0
0 10 20
V2.3.1 CAP
stddev
1.0
2.0
0.0 0 10 20
V2.3.1 CAP RSS RSS
scatt. wind speed (m/s) scatt. wind speed (m/s)
The stddev is large under strong wind condition.
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Rms difference is large under low SST and strong wind conditions.
The CAP product is sensitive to SST and wind speed.
V2.3.1 CAP V2.3.1 RSS V3
Argo temperature(degC)
Win
d s
pee
d (
m/s
)
rms difference
0.0
0.4
0.8
1.2
beam1
Residual analysis (5/6) -SST and wind speed-
rms d
iffe
ren
ce
(p
su
)
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Residual analysis (6/6) -SST and wind speed-
17
V2.3.1 CAP RSS
Argo temperature(degC)
Win
d s
pe
ed
(m
/s)
beam1
beam2
beam3
Rms difference depends on beam for the CAP product.
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Comparison with JAMSTEC Argo OI (1/3)
18
V2.3.1
JAMSTEC Argo OI (10m)
V2.3.1 – JAMSTEC Argo OI
Residual SSS is negative in
low and mid latitudes
rms is 0.25 psu (>0.2 psu)
Jan. 2012
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CAP V2.3.1
JAMSTEC Argo OI (10m)
CAP – JAMSTEC Argo OI
Comparison with JAMSTEC Argo OI (2/3)
Negative bias is small
for the CAP product.
Jan. 2012
rms is 0.18 psu (<0.2 psu)
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2011
Comparison with JAMSTEC Argo OI (3/3)
2012 2013
Jan. 2012
Rms difference is the smallest for the CAP product.
Rms difference (psu) (40S-40N)
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Comparison with JMA assimilation system (1/3)
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V2.3.1
MRI.COM (1m)
V2.3.1 – MRI.COM
Negative bias
rms is 0.23 psu (>0.2 psu)
Jan. 2012
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CAP V2.3.1
CAP – MRI.COM
MRI.COM (1m)
Less negative bias
Comparison with JMA assimilation system (2/3)
rms is 0.18 psu (<0.2 psu)
Jan. 2012
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2011 2012 2013
Rms difference is the smallest for the CAP product.
Comparison with JMA assimilation system (3/3)
Jan. 2012 Rms difference (psu) (40S-40N)
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Summary (1/1)
Aquarius SSSs, retrieved by recent algorisms, were validated
using various salinity data (V2.3.1, CAP V2.3.1, RSS V3).
24
Rms difference was 0.43 – 0.55 psu.
The ascending – descending bias was small for the CAP product.
Rms difference depended on beam for the CAP product.
The negative biases found in the low/mid latitudes were small for
the CAP product.
Rms difference was 0.21 psu (CAP) and 0.23 psu (the others).
Level-2 SSS v.s. Argo, moored buoy
Level-3 SSS v.s. JAMSTEC OI, JMA/MRI.COM
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Backup Slide
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Comparison with in situ data (1/4)
Argo salinity (psu)
V2.3.1 CAP V2.3.1 RSS V3
beam1
Rms difference
0.44 0.55 0.44
Aquarius S
SS
(psu)
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Comparison with in situ data (2/4)
Argo salinity (psu)
V2.3.1 CAP V2.3.1 RSS V3
Rms difference
0.46 0.52 0.47
beam2
Aquarius S
SS
(psu)
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Comparison with in situ data (3/4)
V2.3.1 CAP V2.3.1 RSS V3
Aquarius S
SS
(psu)
Argo salinity (psu)
beam3
Rms difference
0.48 0.50 0.51
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Comparison with in situ data (4/4)
Rms difference is large for the CAP product.
But those are mostly the same in beam3.
CAP
V2.3.1
RSS
Statistical summary
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xy-plot of the collocation points (1/1)
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