Initial Results from the Total Carbon Column Observing Network
description
Transcript of Initial Results from the Total Carbon Column Observing Network
Initial Results from theTotal Carbon Column Observing Network
R.A. Washenfelder1, V. Sherlock2, B.J. Connor2, G.C. Toon3, and P.O. Wennberg1
1 California Institute of Technology (Pasadena, CA)2 National Institute of Water and Atmospheric Research (Lauder, New Zealand)3 NASA Jet Propulsion Laboratory (Pasadena, CA)
Total Carbon Column Observing Network
TCCON is a new network of ground-based near-infrared Fourier Transform Spectrometers dedicated to measurement of greenhouse gases.
Goals for the TCCON Network
1) Assist in constraining the global carbon budget
Compared to surface in situ measurements, column measurements are:• Less sensitive to local sources and sinks• Less sensitive to diurnal and seasonal “rectifier” effects
2) Validate satellite remote sensing instruments
• The Orbiting Carbon Observatory (OCO)• SCIAMACHY• The Greenhouse Gases Observing Satellite (GOSAT)
To learn more about satellite validation:“Overview of OCO Validation” – R. J. Salawitch“Precision Requirements For Space-Based XCO2 Data” – C.E. Miller
Total Carbon Column Observing Network Sites
Current Near-IR Solar ObservatoryPlanned Near-IR Solar ObservatoryOther Future Possibilities
Tall Tower Site in Park Falls, Wisconsin
The laboratory is located next to the 447-m tall WLEF tower, in the Chequamegon National Forest.
This is a site of intensive field measurements by NOAA and other collaborators:• Continuous CO2 monitoring at six levels on Tall Tower• CO2 flux measurements• Weekly flask sampling and monthly aircraft profiles by NOAA CMDL
447
-m W
LEF
tow
er
Park Falls Automated Solar Observatory
Solar tracker
Scanner
Interferometer
Detectors
Solar Beam
Direct sunlight is absorbed at specific wavelengths by atmospheric gases.A Fourier Transform Spectrometer (FTS) records direct solar spectra at high spectral resolution.
Measurements are acquired when the sun is unobscured:• 105 seconds per spectrum.• Full spectrum obtained between
3,900 – 15,600 cm-1 (2.56 – 0.64 μm).• Instrumental alignment is monitored using a sealed cell containing HCl gas.
Gases with absorption features in the near-IR:
CO2, CH4, CO, N2O, H2O, HDO, HF, and O2.
Bruker 120HR spectrometer
Spectral Fitting of Carbon Dioxide
Single forward spectrum (resolution = 0.02 cm-1) recorded at 9:30 am on 9 September 2004.Column CO2 = 7.6466 x 1021 molecules cm-2
Column CO2 / Total Dry Column = 373.94 ± 0.37 ppmv
Calibration of Absolute Column CO2 Using Aircraft Data
Intercontinental Chemical Transport Experiment – North America (INTEX-NA)• NASA DC-8 and King Air measured in situ CO2 during tower profiles• Eight unique aircraft profiles:
DC-8: July 12, July 15 (twice)King Air: July 14, July 15, August 14, August 15 (twice)
Allows us to place our column CO2 retrievals on the same scale as the in situ network.
DC-8 Flight Path and Photograph from 12 July:
46.4
46.2
46.0
45.8
45.6
La
titu
de
(d
eg
)
-91.0 -90.8 -90.6 -90.4 -90.2 -90.0Longitude (deg)
Color = Altitude from 0 - 12 km
15 km
FTS Column and Aircraft In Situ Data – 12 July 04
Aircraft Column / Total Dry Column =372.5 ± 0.52 ppmv
FTS Column / Total Dry Column = 375.5 ± 0.25 ppmv371.4 ± 0.27 ppmv
AIRCRAFT PROFILE: FTS RETRIEVAL:
800
600
400
200
0
Pre
ssur
e (m
b)
390380370360350
CO2 VMR (ppmv)
Median PBL
Median Free Troposphere
Sept 2004 Balloon Profile(Daube and Wofsy)
In Situ CO2 (Vay)
380
375
370
365
CO
2 V
MR
(pp
mv)
10:30 11:00 11:30 12:00 12:30
Local Time (CDT)
CO2 6220 cm-1
band
CO2 6339 cm-1
band
Time of Aircraft Profile
Comparison of FTS Column and Integrated Aircraft CO2
380
375
370
365
360
FT
S C
olum
n / D
ry P
ress
ure
(ppm
v)
380375370365360
Aircraft Integrated Column / Dry Pressure (ppmv)
CO2 6220 cm-1
band = 1.0076 x Aircraft Column
CO2 6339-1
band = 0.995 x Aircraft Column One to one line
Comparison of FTS Column and Integrated Aircraft CO2
380
375
370
365
360
FT
S C
olum
n / D
ry P
ress
ure
(ppm
v)
380375370365360
Aircraft Integrated Column / Dry Pressure (ppmv)
CO2 6220 cm-1
scaled by 1.0076
CO2 6339 cm-1
scaled by 0.995
390
380
370
360
350
340
CO
2 V
MR
(pp
mv)
00:00 12:00 00:00 12:00 00:00 12:00
17 - 19 July 2005
Column Tower at 11-m Tower at 76-m Tower at 396-m
Diurnal Variation of Column and Tall Tower CO2
Arlyn Andrews – preliminary NOAA CMDL Tall Tower data
Relationship between column and in situ CO2 is influenced by:• Drawdown due to photosynthesis• Regional mixing• Boundary layer dynamics
12 ppmv
15 ppmv
Column and Tall Tower CO2 during May 2004 – May 2005
Related poster: “Using A High Resolution Coupled Ecosystem-Atmosphere Model To Evalulate Spatial, Temporal, and Clear-Sky Errors in Satellite CO2 Measurements” – K.D. Corbin
410
400
390
380
370
360
350
340
CO
2 V
MR
(p
pm
v)
5/04 7/04 9/04 11/04 1/05 3/05 5/05
Date
FTS Column Daytime Average Tower at 76-m (11:00 - 15:00 CDT) Tower at 396-m (11:00 - 15:00 CDT)
Initial TCCON Results
Location Lat. Lon. Institution Operational
Park Falls, Wisconsin United States 45.9 N 90.3 W Caltech May 2004
Lauder New Zealand 45.0 S 169.7 E NIWA June 2004
Darwin Australia 12.4 S 90.3 E U Wollongong
CaltechSept 2005
TCCON Measurements and Model Predictions
Vanessa Sherlock and Brian Connor – Lauder CO2 columnsSeth Olsen – MATCH model results
385
380
375
370
365
CO
2 V
MR
(pp
mv)
5/04 7/04 9/04 11/04 1/05 3/05 5/05 7/05 9/05
Date
Park Falls, Wisconsin Lauder, New Zealand Darwin, Australia
LINE = Olsen and Randerson model
Summary
Park Falls, Wisconsin:
• An automated solar observatory has been operational since May 2004.
• Demonstrated precision of ~0.1% for column CO2.
• Linear relationship between column CO2 and integrated aircraft profiles can be used to correct the absolute accuracy of the column CO2 measurements.
Total Carbon Column Observing Network:
• Initial comparisons between Park Falls, Wisconsin and Lauder, New Zealand show that these measurements will capture the interhemispheric seasonal cycle of CO2.
Acknowledgements
Caltech FTS data: Jean-Francois Blavier, Geoffrey Toon, Zhonghua Yang, Yael Yavin, Paul Wennberg
Lauder FTS data: Vanessa Sherlock and Brian Connor
WLEF Tall Tower data: Arlyn Andrews
DC-8 CO2 profiles: Stephanie VayKing Air CO2 profiles: Steven Wofsy and Daniel Matross
Stratospheric CO2 profile: Bruce Daube and Steven Wofsy
Funding: NASA Atmospheric Chemistry, Modeling, and Analysis ProgramNASA Terrestrial Ecology ProgramNASA Orbiting Carbon Observatory
Additional Material
0.3
0.2
0.1
0.0
16000140001200010000800060004000
0.2
0.1
0.0
621062056200
Solar Spectrum Recorded in Park Falls, Wisconsin
InGaAsDetector
Si DiodeDetector
Wavelength (cm-1)
Tra
nsm
issi
on
CO2CO2 O2O2
Single forward spectrum recorded at 9:30 am on 9 Sept 2004. Resolution = 0.02 cm -1.Signal-to-noise: InGaAs Detector ~885; Si Diode Detector ~465
Individual CO2 Lines:
Analysis Method: GFIT
• Line-by-line fitting algorithm for solar absorption spectra
• Developed at the Jet Propulsion Laboratory by Geoff Toon
• Least squares analysis in spectral window to determine slant column abundances for the absorbing gases
• Definition of the fitting residual:
• Atmosphere is represented by 70 vertical levels in forward model
• Pressure and temperature profiles taken from NCEP Reanalysis, with 17 levels from 1000 – 10 mb with 1°×1° geographic resolution
• Climatological temperature profiles used for levels with pressures ≤10 mb
NM
li i
Ci
Mi xYY
χ2
22 ))((
Mii
Ci
Mi
Yσ
x
Y
Y
ofy uncertaint the is
factor scale gas target the is
ncalculatio model forward the is
spectrum one in tmeasuremen one is
390
385
380
375
370
365
CO
2 V
MR
(p
pm
v)
5/04 7/04 9/04 11/04 1/05 3/05 5/05 7/05 9/05
Date
Park Falls Column Daily average
390
385
380
375
370
365
CO
2 V
MR
(p
pm
v)
8/05 9/05
Date
Most Recent Park Falls Data
∆Column CO2 on sunny days: ~3 ppmv day-1 = -12.3 gC m-2 day-1
Davis et al (2003) average daytime NEE June – August 1997 = -4.46 gC m-2 day-1
Treatment of Aircraft Profiles
Profile has been integrated from surface pressure to top of atmosphere.
BELOW AIRCRAFT PROFILE:Assume that median PBL CO2 extends to surface
AIRCRAFT PROFILE:
ABOVE AIRCRAFT PROFILE:Tropopause taken from NCEP reanalysis
Assume that median free tropospheric CO2 extends to tropopause.Stratospheric CO2 profile is taken from September 2004 balloon profile.Assume that CO2 = f(Θ) is reasonably constant in the stratosphere over this time difference.
dp
f
f
m
mmg
fColumn
fffdpmg
fColumn
dznfColumn
Ps
OH
OH
dryair
OHdryair
CO
OHdryCOCO
PsCO
zsCO
0
2
22
2
2,220
2
2
11
1
Averaging Kernels in FTS – Aircraft Comparison
Definition of the averaging kernel:X_hat = (I – A) × Xa + A × X
X_hat = retrieved CO2
X = true CO2
A = averaging kernelXa = a priori profileI = identity matrix
Model Predictions for Column CO2 at 45 °N and 45 °S
FTS Measurement Model Prediction
Park Falls 11 ppmv 8.5 ppmv
Lauder 2 ppmv 2 ppmv
Observed peak-to-peak seasonal amplitude of measured column CO2
compared to model predictions by Olsen and Randerson [2004]:
Model predictions are roughly consistent with actual column measurements.Plans for continued investigation:
Modeling • accuracy of surface flux inventories • parameterization of mixing
Column measurements: • verify that no FTS retrieval bias exists which is dependent on solar zenith angle e.g. averaging kernels or systematic error in the CO2 air-broadened width parameters
Inherent differences between the measurement and the model • comparison of spatially-averaged model results with point observations
Darwin, Australia Site
DOE Atmospheric Radiation Measurement Site
Located on northern Australian coast in the tropics
Three seasons:Dry continental regime from May – SeptemberWet monsoonal season from December – MarchTransitional period between
Existing ARM measurements: Cloud properties, surface meteorology, atmospheric profiling, aerosol properties
Future Measurement Plans
Location Lat. Lon. Institution Operational
Pomona California 34 N 117 W Caltech / JPL Dec 2006
Lamont Oklahoma 37 N 98 W Caltech / JPL May 2007
TCCON Measurements and Model Predictions
Vanessa Sherlock and Brian Connor – Lauder CO2 columnsSeth Olsen – MATCH model results
385
380
375
370
365
CO
2 V
MR
(pp
mv)
5/04 7/04 9/04 11/04 1/05 3/05 5/05 7/05 9/05
Date
Park Falls, Wisconsin Lauder, New Zealand Darwin, Australia
LINE = Olsen and Randerson model