scholarly journals Laboratory measurements of water vapour continuum absorption in spectral region 5000–5600 cm-1: Evidence for water dimers

2004 ◽  
Vol 130 (602) ◽  
pp. 2391-2408 ◽  
Author(s):  
Igor V. Ptashnik ◽  
Kevin M. Smith ◽  
Keith P. Shine ◽  
David A. Newnham
Keyword(s):  
Water Vapour ◽  
Spectral Region ◽  
Laboratory Measurements ◽  
Continuum Absorption ◽  
Water Dimers

scholarly journals Water vapour foreign-continuum absorption in near-infrared windows from laboratory measurements

2012 ◽  
Vol 370 (1968) ◽  
pp. 2557-2577 ◽  
Author(s):  
Igor V. Ptashnik ◽  
Robert A. McPheat ◽  
Keith P. Shine ◽  
Kevin M. Smith ◽  
R. Gary Williams
Keyword(s):  
Water Vapour ◽  
Near Infrared ◽  
Prediction Models ◽  
Weather Prediction ◽  
Pair Interaction ◽  
Atmospheric Conditions ◽  
Laboratory Measurements ◽  
Atmospheric Absorption ◽  
Clear Sky ◽  
Long Time

For a long time, it has been believed that atmospheric absorption of radiation within wavelength regions of relatively high infrared transmittance (so-called ‘windows’) was dominated by the water vapour self-continuum, that is, spectrally smooth absorption caused by H 2 O−H 2 O pair interaction. Absorption due to the foreign continuum (i.e. caused mostly by H 2 O−N 2 bimolecular absorption in the Earth's atmosphere) was considered to be negligible in the windows. We report new retrievals of the water vapour foreign continuum from high-resolution laboratory measurements at temperatures between 350 and 430 K in four near-infrared windows between 1.1 and 5 μm (9000–2000 cm −1 ). Our results indicate that the foreign continuum in these windows has a very weak temperature dependence and is typically between one and two orders of magnitude stronger than that given in representations of the continuum currently used in many climate and weather prediction models. This indicates that absorption owing to the foreign continuum may be comparable to the self-continuum under atmospheric conditions in the investigated windows. The calculated global-average clear-sky atmospheric absorption of solar radiation is increased by approximately 0.46 W m −2 (or 0.6% of the total clear-sky absorption) by using these new measurements when compared with calculations applying the widely used MTCKD (Mlawer–Tobin–Clough–Kneizys–Davies) foreign-continuum model.

Measurements of air-broadening parameters of water vapour transitions in the 7520–8586 cm−1 spectral region

2021 ◽  
Author(s):  
T. M. Petrova ◽  
A. M. Solodov ◽  
A. A. Solodov ◽  
V. M. Deichuli ◽  
V. I. Starikov
Keyword(s):  
Water Vapour ◽  
Spectral Region

Spectral composition of the water vapour self-continuum absorption within 2.7 and 6.25 µm bands

2019 ◽  
Vol 228 ◽  
pp. 97-105 ◽  
Author(s):  
Igor V. Ptashnik ◽  
Tatyana E. Klimeshina ◽  
Alexander A. Solodov ◽  
Andrey A. Vigasin
Keyword(s):  
Water Vapour ◽  
Spectral Composition ◽  
Continuum Absorption

scholarly journals Development and recent evaluation of the MT_CKD model of continuum absorption

2012 ◽  
Vol 370 (1968) ◽  
pp. 2520-2556 ◽  
Author(s):  
Eli J. Mlawer ◽  
Vivienne H. Payne ◽  
Jean-Luc Moncet ◽  
Jennifer S. Delamere ◽  
Matthew J. Alvarado ◽  
...  
Keyword(s):  
Water Vapour ◽  
Line Shape ◽  
Mathematical Formulation ◽  
Field Measurements ◽  
Continuum Absorption ◽  
Semi Empirical ◽  
Vapour Molecule ◽  
Primary Agent ◽  
The Continuum

Water vapour continuum absorption is an important contributor to the Earth's radiative cooling and energy balance. Here, we describe the development and status of the MT_CKD (MlawerTobinCloughKneizysDavies) water vapour continuum absorption model. The perspective adopted in developing the MT_CKD model has been to constrain the model so that it is consistent with quality analyses of spectral atmospheric and laboratory measurements of the foreign and self continuum. For field measurements, only cases for which the characterization of the atmospheric state has been highly scrutinized have been used. Continuum coefficients in spectral regions that have not been subject to compelling analyses are determined by a mathematical formulation of the spectral shape associated with each water vapour monomer line. This formulation, which is based on continuum values in spectral regions in which the coefficients are well constrained by measurements, is applied consistently to all water vapour monomer lines from the microwave to the visible. The results are summed-up (separately for the foreign and self) to obtain continuum coefficients from 0 to 20 000 cm −1 . For each water vapour line, the MT_CKD line shape formulation consists of two components: exponentially decaying far wings of the line plus a contribution from a water vapour molecule undergoing a weak interaction with a second molecule. In the MT_CKD model, the first component is the primary agent for the continuum between water vapour bands, while the second component is responsible for the majority of the continuum within water vapour bands. The MT_CKD model should be regarded as a semi-empirical model with strong constraints provided by the known physics. Keeping the MT_CKD continuum consistent with current observational studies necessitates periodic updates to the water vapour continuum coefficients. In addition to providing details on the MT_CKD line shape formulation, we describe the most recent update to the model, MT_CKD_2.5, which is based on an analysis of satellite- and ground-based observations from 2385 to 2600 cm −1 (approx. 4 μm).

scholarly journals Matching radiative transfer models and radiosonde data from the EPS/Metop Sodankylä campaign to IASI measurements

2011 ◽  
Vol 4 (6) ◽  
pp. 1177-1189 ◽  
Author(s):  
X. Calbet ◽  
R. Kivi ◽  
S. Tjemkes ◽  
F. Montagner ◽  
R. Stuhlmann
Keyword(s):  
Radiative Transfer ◽  
Water Vapour ◽  
Spectral Region ◽  
Radiosonde Data ◽  
Radiative Transfer Models ◽  
Frost Point ◽  
Instrument Noise ◽  
Atmospheric State ◽  
Dry Bias ◽  
Transfer Models

Abstract. Radiances observed from IASI are compared to calculated ones. Calculated radiances are obtained using several radiative transfer models (OSS, LBLRTM v11.3 and v11.6) on best estimates of the atmospheric state vectors. The atmospheric state vectors are derived from cryogenic frost point hygrometer and humidity dry bias corrected RS92 measurements flown on sondes launched 1 h and 5 min before IASI overpass time. The temperature and humidity best estimate profiles are obtained by interpolating or extrapolating these measurements to IASI overpass time. The IASI observed and calculated radiances match to within one sigma IASI instrument noise in the spectral region where water vapour is a strong absorber (wavenumber, ν, in the range of 1500 ≤ ν ≤ 1570 and 1615 ≤ ν ≤ 1800 cm−1).

scholarly journals Application of φ-IASI to IASI: retrieval products evaluation and radiative transfer consistency

2009 ◽  
Vol 9 (22) ◽  
pp. 8771-8783 ◽  
Author(s):  
G. Masiello ◽  
C. Serio ◽  
A. Carissimo ◽  
G. Grieco ◽  
M. Matricardi
Keyword(s):  
Water Vapour ◽  
Forward Model ◽  
Continuum Absorption ◽  
Weather Forecasts ◽  
Time Profiles ◽  
Spectral Residual ◽  
Atmospheric Sounding ◽  
Medium Range ◽  
Temperature Water

Abstract. Retrieval products for temperature, water vapour and ozone have been obtained from spectral radiances measured by the Infrared Atmospheric Sounding Interferometer flying onboard the first European Meteorological Operational satellite. These products have been used to check the consistency of the forward model and its accuracy and the expected retrieval performance. The study has been carried out using a research-oriented forward-inverse methodology, called φ-IASI, that the authors have specifically developed for the new sounding interferometer. The performance of the forward-inversion strategy has been assessed by comparing the retrieved profiles to profiles of temperature, water vapour and ozone obtained by co-locating in space and time profiles from radiosonde observations and from the European Centre for Medium-Range Weather Forecasts analysis. Spectral residuals have also been computed and analyzed to assess the quality of the forward model. Two versions of the high-resolution transmission molecular absorption database have been used, which mostly differ for ozone absorption line parameters, line and continuum absorption of both CO2 and H2O molecules. Their performance has been assessed by inter-comparing the results, and a consistent improvement in the spectral residual has been found when using the most updated release.

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