Impact of new water vapor continuum
coefficients on atmospheric fluxes and
cooling rates.
G. Masiello,
DIFA/UNIBAS
C. Serio,
Dip. di Ingegneria e Fisica dell'Ambiente
F. Esposito, Università degli Studi della Basilicata,
P. Di Girolamo Potenza, Italy
L. Palchetti
IFAC/CNR
Ist. Fisica Applicata, “N. Carrara”
Firenze, Italy
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Outline
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ECOWAR/COBRA
− Campaign
− Instruments
Methodology
Results
− New coefficients for foreign-broadened H2O continuum
− Cooling Rate and fluxes
Conclusion
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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ECOWAR: Earth COoling by WAter vapour Radiation
COBRA: Campagna di Osservazioni della Banda Rotazionale del vapor d’Acqua
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Radiation Emitted by Earth Atmosphere
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Test Site
¾ Breuil-Cervinia
¾ 2000 m a.s.l.
¾ Testa Grigia
¾ 3500 m a.s.l.
‰ Cervino Mountain, Alps (North Italy)
‰ Campaign 3-20 March 2007
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Instruments
More details at
https://www.difa.unibas.it/FM/dlf/progetti/cobra/index.html
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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REFIR (Radiation Explorer in the Far InfraRed)
REFIR/PAD developed at IFAC/CNR
More details in Luca Palchetti talk (C 586)
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REFIR/PAD clear sky spectrum and
related NESR
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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I-BEST
Interferometer for Basic observation of Emitted Spectral Radiance of the Troposphere
I-BEST FTS
ABB-BOMEM MR104
Spectral Range 5-40 µm,
Sampling rate 0.393 cm-1
Operated at Difa/Unibas
Laboratory since 2001
More details in the
poster C 177
Serio C., et al. Applied
Optics, 47,3909-3919
2008.
VAISALA RS-92K
Radio-sounding Unit
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Dealing with Ground Based Far Infrared Spectrum
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Courtesy of S.A. Clough
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Water Vapor Continua
Water vapor absorption Coefficient
Line
foreign continuum
self continuum
Symmetrized Power Spectral Density Function
Let us denote
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Methodology
Spectral radiance
Forward model
spectral parameters
atmospheric state vector T,W
Continuum coefficients vector c is part of the set of spectropic parameters,
Taylor expansion with respect to a initial guess (denoted with 0 suffix)‫‏‬
continuum coeff. Jacobian
T and W Jacobians
Inverted using least square method
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Continuum Jacobian
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Example of a foreign-broadened continuum coefficient Jacobian
for the spectral range of interest to our analysis.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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z
Serio C., Masiello G., Esposito F.,Di Girolamo P.,Di
Iorio T., Palchetti L., Bianchini G., Muscari G., Pavese
G.,Rizzi R., Carli B., Cuomo V., "Retrieval of foreignbroadened water vapor continuum coefficients from
emitted spectral radiance in the H2O rotational band
from 240 to 590 cm-1". Accepted with revison by
Optics Express, 2008.
New water vapor continuum absorption coefficients
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IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
Water vapor foreign-broadened continuum coefficients for the range
240 to 590 cm-1 as derived from our analysis and comparison with
two versions of MT_CKD model and Burch's data (1974).
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Observed-Calculated Residual (REFIR)
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Mean observed and calculated radiance spectrum for the day 9 March 2007
(upper panel) and observed minus calculated (lower panel). The window
channels are evidenced with dot symbols. Calculations are shown using
MT_CKD (version 2.1) and continuum coefficients determined from the three
case studies analyzed in COBRA/ECOWAR campaign.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Observed-Calculated Residual
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REFIR-PAD,
9 March, PWV = 0.6 mm
I-BEST (dtgs),
10 March PWV = 2 mm
I-BEST (mct)‫‏‬
14 March PW = 5.1 mm
Mean observed radiance (upper panel) and observed minus calculated (lower
panel). The window channels are evidenced with dot symbols. Calculations are
shown using MT_CKD (version 2.1) and continuum coefficients determined
from the three case studies analyzed in the ECOWAR/COBRA campaign.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Cooling Rates
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Cooling rate computed for the U.S. Standard atmosphere (Left)
Difference introduced by new coefficients in the spectral range
between 240 – 590 cm-1 (new coefficients – MT_CKD 2.1) (Right)
Differences are positive lower in the Atmosphere.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Radiative Fluxes
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Radiative fluxes (Down, Up and Net)
Net computed for U.S.Std. atmosphere (left)
Difference introduced by new coefficients (right)
− The new coefficients produce a net flux 0.6 W/m2 higher @500 hPa.
− This change is equivalent to that of adding ≈ 50 ppmv of CO2 into the
atmosphere, but in the opposite direction.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Conclusions
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We developed a suitable inverse methodology to retrieve the
continuum coefficients, which allows us to remove possible
uncertainties arising from the input state of the atmosphere. In the
range 240-590 cm−1
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−
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Our new coefficients are in good agreement with the MT_CKD model
in the range 420 to 600 cm−1
In the range 240 to 420 cm−1 , for which our analysis provides the
very first validation of the MT_CKD model in atmospheric conditions,
we found MT_CKD overestimates the observations..
Far infrared window is less absorbing, leading to decreased down
welling fluxes at the surface, and increased up-welling and net fluxes
at the top of the atmosphere
our results once again stress the importance of continuum
parameterization based on data taken in actual atmospheric
conditions and the need of field experiments in the far infrared.
− Basic science issues relevant to our climate are mostly
confined in the far-infrared.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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References
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More Information at www.difa.unibas.it, under
− Research Programs
− COBRA-ECOWAR
− https://www.difa.unibas.it/FM/dlf/progetti/cobra/index.html
R. Bhawar, G. Bianchini, A. Bozzo, M. Cacciani, M. R. Calvello, M.Carlotti, F. Castagnoli, V.
Cuomo, P. Di Girolamo, T. Di Iorio, L. Di Liberto, A. di Sarra, F. Esposito, G. Fiocco, D. Fuà,
G. Grieco, T. Maestri, G. Masiello, G. Muscari, L. Palchetti, , E. Papandrea, G. Pavese, R.
Restieri, R. Rizzi, F. Romano, Carmine Serio, D. Summa, G. Todini, and E. Tosi,
"Spectrally Resolved Observations of Atmospheric Emitted Radiance in the H2O Rotation
Band", GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L04812,
doi:10.1029/2007GL032207, 2008
Serio C., Esposito F., Masiello G., Pavese G., Calvello M.R., Grieco G., Cuomo V., Buijs
H.L. and Roy C.B. "Interferometer for Ground-Based Observations of Emitted Spectral
Radiance from the Troposphere: Evaluation and Retrieval Performance". Applied Optics,
47, 3909-3919 2008.
Serio C., Masiello G., Esposito F.,Di Girolamo P.,Di Iorio T., Palchetti L., Bianchini G.,
Muscari G., Pavese G.,Rizzi R., Carli B., Cuomo V., "Retrieval of foreign-broadened water
vapor continuum coefficients from emitted spectral radiance in the H2O rotational band from
240 to 590 cm-1". Accepted with revision by Optics Express, 2008.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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BACK UP SLIDES
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Objective
†
Perform a field campaign in the Mountains (Alps) to observe
atmospheric emitted spectral radiance in condition of low water
vapour content, and use them
„
„
„
„
Validation of models of atmospheric radiative transfer in cloudy
and clear skies;
Evaluation of spectral absorption properties of water vapour in
the rotational band from 200 to 600 (cm-1);
Evaluation of the modelling capability in clear and cloudy
conditions and reconstruction of the radiative diabatic effects;
Demonstration of the rotational water vapour band capability as a
temperature and humidity sounding system, especially to
discriminate lower troposphere water vapour from its
concentration in the higher troposphere.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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I-BEST SPECTRUM
•
From:
z Tobin, D.C., F.A. Best, P.D. Brown, S.A. Clough, R.G. Dedecker, R.G. Ellingson, R.K.
Garcia, H.B. Howell, R.O. Knuteson, E.J. Mlawer, H.E. Revercomb, J.F. Short, P.F.W. van
Delst, and V.P. Walden, 1999. "Downwelling spectral radiance observations at the SHEBA
ice station: Water vapor continuum measurements from 17 to 26µm," JGR 104(D2): 20812092
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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ECOWAR/COBRA
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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Effective Temperature
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Window channels, spectral ranges and effective temperatures for
the three days analyzed in the paper. Spectral ranges differ each
from other because they refer to different instruments and detector
mode.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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REFIR
REFIR/PAD developed at IFAC/CNR
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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BASIL LIDAR
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DIFA-Università della Basificata Lidar
−
−
−
−
−
−
Short Name: BASIL
particle backscatter at 355 and 532 nm
particle extinction at 355 nm
particle depolarization at 355 nm
water vapour mixing ratio
atmospheric temperature
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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LIDAR Water vapor mixing ratio map
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Water vapor mixing ratio for the night between 9 and 10 March
2007.
IRS2008 Symposiunm, Foz do Iguaçu, Brazil, 8 August 2008. Section C 181, Guido Masiello
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