Atmospheric correction of ENVISAT/MERIS data over case II waters: the use of black pixel assumption in oxygen and water vapour absorption bands

Abstract. In recent updates of the HITRAN water vapour H2O spectroscopic compilation covering the blue spectral region (here: 394–480 nm) significant changes for the absorption bands at 416 and 426 nm were reported. In order to investigate the consistency of the different cross-sections calculated from these compilations, H2O vapour column density ratios for different spectral intervals were retrieved from Long-path and Multi-Axis – Differential Optical Absorption Spectroscopy (DOAS) measurements. We observed a significant improvement of the DOAS evaluation when using the updated HITRAN water vapour absorption cross-sections for the calculation of the reference spectra. In particular the magnitudes of the residual spectra as well as the fit errors were reduced. However we also found that the best match between measurement and model is reached when the absorption cross-section of groups of lines are scaled by factors ranging from 0.5 and 1.9, suggesting that the HITRAN water vapour absorption compilation still needs significant corrections. For this spectral region we present correction factors for HITRAN 2009, HITRAN 2012, HITEMP and BT2 derived from field measurements. Additionally, upper limits for water vapour absorption in the UV-A range from 330–390 nm are given.

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On the relative absorption strengths of water vapour in the blue wavelength range

Atmospheric Measurement Techniques ◽

10.5194/amt-8-4329-2015 ◽

2015 ◽

Vol 8 (10) ◽

pp. 4329-4346 ◽

Cited By ~ 15

Author(s):

J. Lampel ◽

D. Pöhler ◽

J. Tschritter ◽

U. Frieß ◽

U. Platt

Keyword(s):

Water Vapour ◽

Cross Sections ◽

Spectral Region ◽

Field Measurements ◽

Optical Absorption Spectroscopy ◽

Absorption Cross ◽

Absorption Bands ◽

Blue Wavelength ◽

Water Vapour Absorption ◽

Density Ratios

Abstract. In recent updates of the HITRAN water vapour H2O spectroscopic compilation covering the blue spectral region (here: 394–480 nm) significant changes for the absorption bands at 416 and 426 nm were reported. In order to investigate the consistency of the different cross-sections calculated from these compilations, H2O vapour column density ratios for different spectral intervals were retrieved from long-path and multi-axis differential optical absorption spectroscopy (DOAS) measurements. We observed a significant improvement of the DOAS evaluation when using the updated HITRAN water vapour absorption cross-sections for the calculation of the reference spectra. In particular the magnitudes of the residual spectra as well as the fit errors were reduced. However, we also found that the best match between measurement and model is reached when the absorption cross-section of groups of lines are scaled by factors ranging from 0.5 to 1.9, suggesting that the HITRAN water vapour absorption compilation still needs significant corrections. For this spectral region we present correction factors for HITRAN 2009, HITRAN 2012, HITEMP and BT2 derived from field measurements. Additionally, upper limits for water vapour absorption in the UV-A range from 330 to 390 nm are given.

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1D-Var retrieval of daytime total columnar water vapour from MERIS measurements

Atmospheric Measurement Techniques ◽

10.5194/amt-5-631-2012 ◽

2012 ◽

Vol 5 (3) ◽

pp. 631-646 ◽

Cited By ~ 28

Author(s):

R. Lindstrot ◽

R. Preusker ◽

H. Diedrich ◽

L. Doppler ◽

R. Bennartz ◽

...

Keyword(s):

Water Vapour ◽

Root Mean Square ◽

Atmospheric Correction ◽

Pressure Profile ◽

Mean Square ◽

Imaging Spectrometer ◽

Atmospheric Scattering ◽

Full Resolution ◽

Medium Resolution ◽

Water Vapour Absorption

Abstract. A new scheme for the retrieval of total columnar water vapour from measurements of MERIS (Medium Resolution Imaging Spectrometer) on ENVISAT (ENVIronmental SATellite) is presented. The algorithm is based on a fast forward model of the water vapour transmittance around 900nm, including a correction for atmospheric scattering and the influence of the temperature- and pressure-profile on the water vapour absorption lines. It provides the water vapour column amount for cloud-free scenes above land and ocean at a spatial resolution of 0.25 km × 0.3 km and 1 km × 1.2 km, depending on whether applied to the "full resolution" or the operational "reduced resolution" mode of MERIS. Uncertainties are provided on a pixel-by-pixel basis, taking into account all relevant sources of error. An extensive validation against various sources of ground-based reference data reveals a high accuracy of MERIS water vapour above land (root mean square deviations between 1.4 mm and 3.7 mm), apart from a wet bias of MERIS between 5 and 10% that is found in all comparison studies. This wet bias might be caused by spectroscopic uncertainties, such as the description of the water vapour continuum. Above ocean the accuracy is reduced, due to the uncertainty introduced by the unknown atmospheric scattering. Consequently, an increased root mean square deviation of ≥5 mm was found by comparing MERIS total columnar water vapour above ocean against SSM/I and ENVISAT MWR data. An increased wet bias of 2–3 mm is found over ocean, potentially due to a not properly working atmospheric correction scheme.

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Discriminating between hazy and clear hot-Jupiter atmospheres with CARMENES

Astronomy and Astrophysics ◽

10.1051/0004-6361/202038629 ◽

2020 ◽

Vol 643 ◽

pp. A24

Author(s):

A. Sánchez-López ◽

M. López-Puertas ◽

I. A. G. Snellen ◽

E. Nagel ◽

F. F. Bauer ◽

...

Keyword(s):

High Altitude ◽

Water Vapour ◽

Rayleigh Scattering ◽

Near Infrared ◽

Relative Strength ◽

High Spectral Resolution ◽

Absorption Bands ◽

Infrared Wavelength ◽

Hot Jupiters ◽

Water Vapour Absorption

Context. Relatively large radii of some hot Jupiters observed in the ultraviolet and blue-optical are generally interpreted to be due to Rayleigh scattering by high-altitude haze particles. However, the haze composition and its production mechanisms are not fully understood, and observational information is still limited. Aims. We aim to study the presence of hazes in the atmospheres of HD 209458 b and HD 189733 b with high spectral resolution spectra by analysing the strength of water vapour cross-correlation signals across the red optical and near-infrared wavelength ranges. Methods. A total of seven transits of the two planets were observed with the CARMENES spectrograph at the 3.5 m Calar Alto telescope. Their Doppler-shifted signals were disentangled from the telluric and stellar contributions using the detrending algorithm SYSREM. The residual spectra were subsequently cross-correlated with water vapour templates at 0.70–0.96 μm to measure the strength of the water vapour absorption bands. Results. The optical water vapour bands were detected at 5.2σ in HD 209458 b in one transit, whereas no evidence of them was found in four transits of HD 189733 b. Therefore, the relative strength of the optical water bands compared to those in the near-infrared were found to be larger in HD 209458 b than in HD 189733 b. Conclusions. We interpret the non-detection of optical water bands in the transmission spectra of HD 189733 b, compared to the detection in HD 209458 b, to be due to the presence of high-altitude hazes in the former planet, which are largely absent in the latter. This is consistent with previous measurements with the Hubble Space Telescope. We show that currently available CARMENES observations of hot Jupiters can be used to investigate the presence of haze extinction in their atmospheres.

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Leather. Physical and mechanical tests. Determination of water vapour absorption

10.3403/02728662 ◽

2003 ◽

Keyword(s):

Water Vapour ◽

Mechanical Tests ◽

Water Vapour Absorption

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Methods of testing plastics. Methods 502, 503 and 504 water absorption and water soluble matter, boiling water absorption and water vapour absorption.

10.3403/30308452u ◽

2015 ◽

Keyword(s):

Water Absorption ◽

Water Vapour ◽

Water Soluble ◽

Boiling Water ◽

Water Vapour Absorption

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Leather. Physical and mechanical tests. Determination of water vapour absorption

10.3403/30324954 ◽

2016 ◽

Keyword(s):

Water Vapour ◽

Mechanical Tests ◽

Water Vapour Absorption

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The Impact of Post-Manufacture Treatments on the Surface Characteristics Important for Finishing of OSB and Particleboard

Forests ◽

10.3390/f12080975 ◽

2021 ◽

Vol 12 (8) ◽

pp. 975

Author(s):

Antonio Copak ◽

Vlatka Jirouš-Rajković ◽

Nikola Španić ◽

Josip Miklečić

Keyword(s):

Water Vapour ◽

Oriented Strand Board ◽

Construction Material ◽

Surface Characteristics ◽

Surface Treatments ◽

Factors Affecting ◽

Treatment Conditions ◽

Water Vapour Absorption ◽

The Impact

Oriented strand board (OSB) is a commonly used structural wood-based panel for walls and roof siding, but recently the industry has become interested in OSB as a substrate for indoor and outdoor furniture. Particleboard is mainly used in furniture productions and has become popular as a construction material due to its numerous usage possibilities and inexpensive cost. Moisture is one of the most important factors affecting wood-based panel performance and the post-treatment conditions affected their affinity to water. When OSB and particleboard are used as substrates for coatings, their surface characteristics play an important role in determining the quality of the final product. Furthermore, roughness can significantly affect the interfacial phenomena such as adsorption, wetting, and adhesion which may have an impact on the coating performance. In this research particleboard and OSB panels were sanded, re-pressed and IR heated and the influence of surface treatments on hardness, roughness, wetting, water, and water vapour absorption was studied. Results showed that sanding improved the wetting of particleboard and OSB with water. Moreover, studied surface treatments increased water absorption and water penetration depth of OSB panels, and re-pressing had a positive effect on reducing the water vapour absorption of particleboard and OSB panels.

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