Downwelling spectral radiance observations at the SHEBA ice station: Water vapor continuum measurements from 17 to 26μm

Tobin, David C.; Best, Fred A.; Brown, P.; Clough, S. A.; Dedecker, R. G.; Ellingson, Robert G.; Garcia, Ray; Howell, H. B.; Knuteson, Robert O.; Mlawer, E. J.; Revercomb, Henry E.; Short, J. F.; Delst, Paul F. W. van; Walden, Von P.

doi:10.1029/1998jd200057

Cited by 124 publications

(104 citation statements)

References 27 publications

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“…Although clear-sky longwave modeling is quite accurate for warmer climates there is still some uncertainty for cold and dry climates due to the above mentioned microwindows [Tobin et al, 1999]. A recent comparison of downward longwave irradiances between global climate models and the best available surface measurements shows an especially large disagreement at observation sites in cold and dry climates [Wild et al, 2001].…”

Section: Rationalementioning

confidence: 99%

“…LBLRTM radiance calculations have been extensively validated against highresolution spectral measurements for many climatic conditions [Clough et al, 2000;Tobin et al, 1999;. A significant feature in LBLRTM v6.12 is a modification to the carbon dioxide continuum and the carbon dioxide line shape.…”

Section: Radiative Transfer Modelsmentioning

confidence: 99%

“…The AERI-ER is calibrated to within 1% of the ambient radiance [Knutson et al, 1998] by having the interferometer view high-emissivity blackbody cavities before and after every scene view. The AERI-ER is an ideal instrument to measure the climatologically important microwindow radiances below 600 cm À1 , and therefore provides an important contribution to Arctic clear-sky measurement and model intercomparisons [Tobin et al, 1999].…”

Section: Extended-range Atmospheric Emitted Radiance Interferometermentioning

confidence: 99%

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Downward longwave irradiance uncertainty under arctic atmospheres: Measurements and modeling

et al. 2003

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[1] Measurement and modeling of downward longwave irradiance are a special challenge in arctic winter due to its low water vapor content and the extreme meteorological conditions. There are questions about the representativeness of the instrument calibration, the consistency and uncertainty of measurements and models in these environments. The Second International Pyrgeometer and Absolute Sky-scanning Radiometer Comparison (IPASRC-II), which was conducted at Atmospheric Radiation Measurement (ARM) program's North Slope of Alaska (NSA) site in Barrow provided a unique opportunity to compare high accuracy downward longwave irradiance measurements and radiative transfer model computations during arctic winter. Participants from 11 international institutions deployed 14 pyrgeometers, which were field-calibrated against the Absolute Sky-scanning Radiometer (ASR). Continuous measurements over a 10-day period in early

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Section: Rationalementioning

confidence: 99%

Section: Radiative Transfer Modelsmentioning

confidence: 99%

Section: Extended-range Atmospheric Emitted Radiance Interferometermentioning

confidence: 99%

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Downward longwave irradiance uncertainty under arctic atmospheres: Measurements and modeling

et al. 2003

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“…The calculations are based upon the HITRAN spectral line data [Rothman et al, 2003] and CKD2.4 water vapor continuum absorption formulation [Tobin et al, 1999]. Temperature and water vapor follow the standard tropical profiles [McClatchey et al, 1972].…”

Section: Longwave Radiative Transfer Formulationmentioning

confidence: 99%

Effect of the temperature dependence of gas absorption in climate feedback

Huang

Ramaswamy

2007

J. Geophys. Res.

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[1] In the context of climate feedback associated with temperature change, there exist two potential mechanisms that affect the outgoing longwave radiation (OLR) and the downward longwave radiation (DLR). One is the ''Planck'' effect that determines the blackbody thermal emission at a considered temperature. The other is the ''absorptivity'' effect, in which a temperature change causes a change in gas absorptivities and thus influences the longwave radiative transfer. By using the line-by-line computed radiative Jacobians, which quantify the sensitivity of the radiative fluxes to a perturbation in the atmospheric temperature, the absorptivity effect is separated from the Planck effect. The absorptivity effect is further partitioned into components, with each one having a distinct physical meaning. It is demonstrated that the absorptivity-induced changes in the longwave radiation are individually significant even though the net effect is largely one of cancellation. As a consequence, the Planck effect dominates the overall OLR and DLR sensitivities to temperature change. The absorptivity effect tends to counteract the Planck effect. This tendency is particularly significant for the DLR and is more prominent for a warmer climate, with the result being a reduction in the surface warming.Citation: Huang, Y., and V. Ramaswamy (2007), Effect of the temperature dependence of gas absorption in climate feedback,

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“…Furthermore, the spectroscopy of water vapour also poses some problems. The high concentration of this species in the lower troposphere makes relevant several spectroscopic processes (self and foreign broadening, pressure shift, and continuum absorption) (Tobin et al, 1999) that are difficult to observe in laboratory conditions and thus require a field validation. Within this context, Sinha and Harries (1995) pointed out the lack of validation of far infrared (FIR) model line parameters of water vapour in atmospheric conditions, and stressed that FIR parameterisation in climate models should be validated by means of observational programmes.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the water vapour vertical profile and of the Earth's outgoing far infrared flux

Palchetti

Bianchini²,

Carli³

et al. 2008

Atmos. Chem. Phys.

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Abstract. Our understanding of global warming depends on the accuracy with which the atmospheric components that modulate the Earth's radiation budget are known. Many uncertainties still exist as regards the radiative effect of water in the different spectral regions, among which is the far infrared, where very few observations have been made. An assessment is shown of the atmospheric outgoing flux obtained from a balloon-borne platform with wideband spectrallyresolved nadir measurements at the top of the atmosphere over the full spectral range, from 100 to 1400 cm −1 , made by a Fourier transform spectrometer with uncooled detectors. From these measurements, we retrieved 15 pieces of information regarding water vapour and temperature profiles and surface temperature, with a major improvement in our knowledge of water vapour in the upper troposphere. The retrieved atmospheric state made it possible to calculate the emitted radiance also at frequencies and zenith angles that have not been observed and to determine the outgoing spectral radiation flux. This proves that spectrally resolved observations can be used to derive accurate information on the integrated flux. While the retrieved temperature was in agreement with ECMWF analysis, the retrieved water vapour profile differed significantly; depending on the time and the location, the derived flux in the far infrared (20-600 cm −1 ) differed by 2-3.5 W/m 2 from that calculated using ECMWF. The error with which the far infrared flux is determined by REFIR-PAD is about 0.4 W/m 2 and is caused mainly by calibration uncertainties, while detector noise has a negligible effect. This proves that uncooled detectors are adequate for top-of-the-atmosphere radiometry.

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Downwelling spectral radiance observations at the SHEBA ice station: Water vapor continuum measurements from 17 to 26μm

Cited by 124 publications

References 27 publications

Downward longwave irradiance uncertainty under arctic atmospheres: Measurements and modeling

Downward longwave irradiance uncertainty under arctic atmospheres: Measurements and modeling

Effect of the temperature dependence of gas absorption in climate feedback

Measurement of the water vapour vertical profile and of the Earth's outgoing far infrared flux

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