Ocean Heat and Salt Calculations
using Argo data at NODC
Tim Boyer
Ocean Climate Laboratory
National Oceanographic Data Center
NESDIS/NOAA
September 27, 2012
Outline
• Changing Ocean Observing System
• Processing of Argo data at NODC: archiving
to globally integrated heat/salt calculations
•Recently Published Results: global heat and
salt changes
• Reexamination of quality control algorithms
at NODC due to Argo data
• Ocean heat content at deeper depths
The Changing Ocean Observing
System
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Temperature Data During Peak of Different
Observing Systems
1934 : Nansen Cast
Red=Nansen Cast /CTD[1890s/1964]
Light Blue=MBT [1939]
Dark Blue=XBT [1967]
Green=Argo float [2001]
Orange=Tropical buoy [1984]
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Temperature Data During Peak of Different
Observing Systems
1934 : Nansen Cast
1960 : MBT
Red=Nansen Cast /CTD[1890s/1964]
Light Blue=MBT [1939]
Dark Blue=XBT [1967]
Green=Argo float [2001]
Orange=Tropical buoy [1984]
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Temperature Data During Peak of Different
Observing Systems
1934 : Nansen Cast
1960 : MBT
1985 : XBT
Red=Nansen Cast /CTD[1890s/1964]
Light Blue=MBT [1939]
Dark Blue=XBT [1967]
Green=Argo float [2001]
Orange=Tropical buoy [1984]
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Temperature Data During Peak of Different
Observing Systems
1934 : Nansen Cast
1960 : MBT
1985 : XBT
Red=Nansen Cast /CTD[1890s/1964]
Light Blue=MBT [1939]
Dark Blue=XBT [1967]
Green=Argo float [2001]
Orange=Tropical buoy [1984]
2009 :
Argo
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Data Flow: Argo Data
through NODC
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http://www.usgodae.org/argo/argo.html
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http://www.nodc.noaa.gov/OC5/WOD/pr_wod.html
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http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/
http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/
World Ocean Heat Content (1955-2010) based on running pentads (5-year periods)
Levitus et al. (2012)
The 0-2000 m layer of the
world ocean has warmed by
~ 0.09°C [24.0±1.9x1022 J] in
the 1955-2010 period.
30% of ocean warming for
the 1955-2010 period
occurred in the 700-2000 m
layer
World Ocean heat content (1022 J) (1955-2010) for the 0-2000 m (red) and 700-2000 m (black) layers of the world ocean based on running
pentadal (five-year) analyses. Reference period is 1955-2006.
Each pentadal estimate is plotted at the midpoint of the 5-year period. The vertical bars represent +/- 2.*S.E. about the pentadal estimate for
the 0-2000 m estimates and the grey-shaded area represent +/- 2.*S.E. about the pentadal estimate for each 0-700 m estimate.
The blue bar chart at the bottom represents the percentage of one-degree squares (globally) that have at least four pentadal one-degree square
anomaly values used to compute one-degree square values at 700 m depth.
The blue line is the same quantity as for the bar chart but for 2000 m depth.
OHCA calculations using different mapping (smoothing/infill)
methods from same input dataset (same quality control, same base
climatology, same XBT corrections [Wijffels et al. 2008)
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September 2011 Salinity Anomaly at 10 m depth
Red=positive anomaly
Blue=negative anomaly
Contour Interval 0.20
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2011 Mean Salinity Anomaly 0-100 m depth
Red=positive anomaly
Blue=negative anomaly
Contour Interval 0.10
Boyer et al., 2012 - BAMS State of the Climate 2011: Subsurface Salinity
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NODC archives new/changed Argo data daily and the entire
Argo database monthly
NODC does additional quality control and incorporates Argo
data into the World Ocean Database (Argo flags are also
included)
NODC calculates ocean heat content anomaly, changes to
thermosteric, halosteric, and total steric sea level on a
seasonal, yearly and pentadal basis 1955 to present
(updated seasonally).
NODC will soon add mean temperature and salinity anomaly
0-100m, 0-700m and 0-2000m
NODC conducts research on ocean heat content/salt content
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REXAMINATION OF QUALITY
CONTROL PROCEDURES AT
NODC BASED ON RESULTS
USING ARGO DATA
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•Extensive and intensive quality control work
done Argo profile data by Data Assembly
Centers (DAC)
•Additional quality control work done upon
arrival of data at NODC
•What are the effects of Argo quality control
and NODC quality control on ocean heat
content calculations?
•Based on work done by Mathieu Hamon [PhD
thesis] with Karina von Schuckmann and
Gilles Reverdin [heat content discrepancy in
southern hemisphere using WOD05 + Argo qc
data vs WOD09 with NODC qc Argo data]
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Ocean Heat Content
Anomaly (OHCA) 0-700m
integrated over 65S to
65N (dashed lines) and
over 60S to 30S (solid
lines) using Argo quality
control (blue lines) and
NODC quality control
(orange lines)
For 2009 (units=1022J):
65S-65N NODC 10.12
65S-65N Argo 11.35
60S-30S NODC
60S-30S Argo
1.72
2.98
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YEAR 2009 0-700 m OCEAN HEAT CONTENT
ANOMALY (OHCA) RELATIVE TO WOA09
ABOVE: FULL NODC QUALITY CONTROL
BELOW: ARGO QC FLAG 4 ONLY
ABOVE: NODC QC OHCA MINUS
ARGO QC FLAG 4 OHCA
RED=POSITIVE OHCA
BLUE=NEGATIVE OHCA
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Global Subsurface Temperature
Coverage: 60S to 30S compared
to Global Ocean
1985 [5%]
2009 [22%]
Profiles with Two or More Depth Levels with
Temperature Standard Deviation Outliers:
Global Ocean compared to 60S – 30S latitudes.
Left Panel: Number of Profiles
Right Panel: Percent of Total Profiles
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World Ocean Atlas Annual
Mean Temperature Climatology
at 600 m depth.
Solid Grey Line=5° mean
temperature. Dashed Grey
Lines=Mean ± 3 x Standard
Deviation
Float 5900242 – Cycle 25
September 9, 2003
50.3°S, 140.5°E
Black line=Temperature profile
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•One possibility: standard deviation check is
flagging too many good data
•New more inclusive climatology (WOA13),
shorter time period climatology (WOA13) or
float-only climatology (Roemmich and
Gilson) may help
•Change or remove check
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•Second possibility: standard deviation
check flagged data represent limited
time/space features and should not be used
for OHCA calculation
•Continue as before
•Change checks for known frequent
anomalous regions (Agulhas
retroflection/rings) and anomalous time
periods (1997-98 El Niño/La Niña)
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Exploration of data coverage to
adequately describe deep ocean
heat content anomaly
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Temperature Data Distribution
2006-2010
2000 meters
Profiles per one-degree box
Black = 1 profile
Green= 2-5 profiles
Orange=> 6-30 profiles
Red > 30 profiles
2000 decibars
Heat Content 0-2000 m=
14.59 x 10 22 J
Heat Content 0 m-2000 db=
14.61 x 1022J
Heat Content 1875-2000m=
0.17 x 1022J ± 0.10 x 1022J
Heat Content 1875 m-2000 db=
0.19 x 1022J ± 0.03 x 1022J
Depth of 2000db ranges from
~1980m at the Equator to
~1970m at the Pole using
Saunders and Fofonoff (1976).
Ocean Heat Content Anomaly 2006-2010
by 100m depth bins with error bars
(2x standard error of the mean)
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Temperature Anomaly
2006-2010
2000 meters
Contour Interval 0.05°C
Red=positive anomaly
Blue=Negative anomaly
2000 decibars
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• Integrating to 2000 m as opposed to 2000 db
makes only a small difference in OHCA
despite large difference in data coverage, but
uncertainty is much larger
• Implications for Deep Argo: Find a balance
between data coverage and acceptable
uncertainty
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Summary
• Argo has revolutionized the ocean observing system
• NODC archives, extends the reach of, and utilizes
Argo data for globally integrated heat and salt
calculations and scientific research
• Argo forces a reanalysis of the meaning and
utilization of the standard deviation quality control
check
• Argo coverage at deeper levels need be minimally
sufficient to lower uncertainties to acceptable levels
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