Field measurements of water vapor continuum absorption in the visible and near‐infrared

Sierk, B.

doi:10.1029/2003jd003586

Cited by 31 publications

(23 citation statements)

References 46 publications

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“…By comparing to narrowband radiometer observations of a narrowband radiometer used in the Atmospheric Radiation Measurement Enhanced Shortwave Experiment (ARESE), Vogelmann et al [1998] found that the CKD continuum (version 2.2) is likely too large in the 950 nm region. This is consistent with the results of Sierk et al [2004], in which spectral atmospheric continuum estimates from direct sun observations were used to conclude that the MT_CKD continuum exhibits a similar spectral shape but a larger magnitude by about 50% in this wavelength region (about 100% for CKD version 2.4.1). Sierk et al [2004] also found that the MT_CKD parameterization underestimates the continuum absorption in the 720 nm band by about 40%, while CKD version 2.4.1 demonstrates good agreement.…”

Section: Introductionmentioning

confidence: 99%

“…This is consistent with the results of Sierk et al [2004], in which spectral atmospheric continuum estimates from direct sun observations were used to conclude that the MT_CKD continuum exhibits a similar spectral shape but a larger magnitude by about 50% in this wavelength region (about 100% for CKD version 2.4.1). Sierk et al [2004] also found that the MT_CKD parameterization underestimates the continuum absorption in the 720 nm band by about 40%, while CKD version 2.4.1 demonstrates good agreement. Furthermore, it has been suggested that water dimer absorption may be implicitly included in the CKD continuum model based on laboratory observations between 5,000 and 5,600 cm −1 [ Ptashnik et al , 2004].…”

Section: Introductionmentioning

confidence: 99%

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Atmospheric water vapor complexes and the continuum

Daniel

Solomon

Kjaergaard

et al. 2004

Geophysical Research Letters

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[1] Estimates of absorption optical depths for the bound complexes H 2 O-H 2 O and the sum of H 2 O-N 2 , H 2 O-O 2 , and H 2 O-Ar at visible and near-infrared wavelengths are compared to the same quantities calculated from a frequently used water continuum parameterization (MT_CKD) and from a theoretical far wing water vapor lineshape theory. The temperature dependences of some of these optical depths are also compared. The comparisons suggest qualitatively that water complexes may contribute to the continuum at these wavelengths, and show that the temperature dependence of the continuum might provide insight into the role of the complexes in the atmosphere. Because of the dearth of laboratory measurements of the continuum at these wavelengths, and because the current estimates for the equilibrium constants of these water vapor complexes remain highly uncertain, more observations are needed before the importance of water complexes can be accurately quantified.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atmospheric water vapor complexes and the continuum

Daniel

Solomon

Kjaergaard

et al. 2004

Geophysical Research Letters

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“…The photomorphogenetically active FR spectrum (Borthwick, 1972;Mohr, 1972) corresponds to the 700-740 nm band of water vapour absorption (Robinson, 1966). Moreover, the maximum of the action spectrum in the high irradiance response (HIR) lies at 720 nm (Hartmann, 1966), which coincides with the peak of absorption (Gueymard, 1995;Sierk et al, 2004) in this band (Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

Atmospheric moisture controls far-red irradiation: a probable impact on the phytochrome

Doroszewski

Górski

Kozyra

2015

International Agrophysics

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A b s t r a c t. It is commonly accepted that an important role of the phytochrome lies in signalling the proximity of competing plants. However, not all photoresponses conveyed by the phytochrome can be explained by the competition only. Because a better description of the natural variability of solar spectral irradiance is necessary to recognize the other roles of the phytochrome, long-lasting spectroradiometric measurements have been performed. Special attention has been paid to the relations between the far-red and red bands of the solar spectrum, which have an impact on the phytochrome. The effect of atmospheric moisture on far-red irradiance (attenuated in the 720 nm band of water vapour absorption) is described. The far-red irradiance, active in the 'high irradiance response' of the phytochrome, and the red/ far-red ratio, important for the 'low fluence response', may vary very strongly relative to the atmospheric moisture. Together with other facts known from photophysiology, the results of the measurements enabled us to formulate a thesis that the phytochrome monitors the amount of water vapour and opens appropriate metabolic pathways to cope with the danger of drought. The recognition of this novel role of the phytochrome might broaden the knowledge in the area of plant photomorphogenesis and ecology.

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“…Coming to the NIR we note that for this spectral region to our knowledge no atmospheric radiative closure experiments have been reported in the literature with the exception of the studies by Sierk et al (2004) and Mlawer et al (2014). A hindrance for quantitative field studies may have been the fact that absorption in the NIR due to aerosols can become comparable to the magnitude of the water vapor continuum absorption of interest .…”

Section: Introductionmentioning

confidence: 88%

The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 1: Setup, uncertainty analysis, and assessment of far-infrared water vapor continuum

2016

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Abstract. Quantitative knowledge of water vapor radiative processes in the atmosphere throughout the terrestrial and solar infrared spectrum is still incomplete even though this is crucial input to the radiation codes forming the core of both remote sensing methods and climate simulations. Beside laboratory spectroscopy, ground-based remote sensing field studies in the context of so-called radiative closure experiments are a powerful approach because this is the only way to quantify water absorption under cold atmospheric conditions. For this purpose, we have set up at the Zugspitze (47.42 • N, 10.98 • E; 2964 m a.s.l.) a long-term radiative closure experiment designed to cover the infrared spectrum between 400 and 7800 cm −1 (1.28-25 µm). As a benefit for such experiments, the atmospheric states at the Zugspitze frequently comprise very low integrated water vapor (IWV; minimum = 0.1 mm, median = 2.3 mm) and very low aerosol optical depth (AOD = 0.0024-0.0032 at 7800 cm −1 at air mass 1). All instruments for radiance measurements and atmospheric-state measurements are described along with their measurement uncertainties. Based on all parameter uncertainties and the corresponding radiance Jacobians, a systematic residual radiance uncertainty budget has been set up to characterize the sensitivity of the radiative closure over the whole infrared spectral range. The dominant uncertainty contribution in the spectral windows used for far-infrared (FIR) continuum quantification is from IWV uncertainties, while T profile uncertainties dominate in the mid-infrared (MIR). Uncertainty contributions to near-infrared (NIR) radiance residuals are dominated by water vapor line parameters in the vicinity of the strong water vapor bands. The window regions in between these bands are dominated by solar Fourier transform infrared (FTIR) calibration uncertainties at low NIR wavenumbers, while uncertainties due to AOD become an increasing and dominant contribution towards higher NIR wavenumbers. Exceptions are methane or nitrous oxide bands in the NIR, where the associated line parameter uncertainties dominate the overall uncertainty.As a first demonstration of the Zugspitze closure experiment, a water vapor continuum quantification in the FIR spectral region (400-580 cm −1 ) has been performed. The resulting FIR foreign-continuum coefficients are consistent with the MT_CKD 2.5.2 continuum model and also agree with the most recent atmospheric closure study carried out in Antarctica. Results from the first determination of the NIR water vapor continuum in a field experiment are detailed in a companion paper (Reichert and Sussmann, 2016) while a novel NIR calibration scheme for the underlying FTIR measurements of incoming solar radiance is presented in another companion paper .

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Field measurements of water vapor continuum absorption in the visible and near‐infrared

Cited by 31 publications

References 46 publications

Atmospheric water vapor complexes and the continuum

Atmospheric water vapor complexes and the continuum

Atmospheric moisture controls far-red irradiation: a probable impact on the phytochrome

The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 1: Setup, uncertainty analysis, and assessment of far-infrared water vapor continuum

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