scholarly journals Imaging Considerations from a Geostationary Orbit using the Short Wavelength Side of the Mid‐Infrared Water Vapor Absorption Band

2022 ◽  
Author(s):  
N. B. Miller ◽  
M. M. Gunshor ◽  
A. J. Merrelli ◽  
T. S. L’Ecuyer ◽  
T. J. Schmit ◽  
...  
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Short Wavelength ◽  
Geostationary Orbit ◽  
Water Vapor Absorption ◽  
Mid Infrared ◽  
Vapor Absorption ◽  
Short Wavelength Side ◽  
Wavelength Side

Homogenized Water Vapor Absorption Band Radiances From International Geostationary Satellites

2019 ◽  
Vol 46 (17-18) ◽  
pp. 10599-10608 ◽  
Author(s):  
Zhenglong Li ◽  
Jun Li ◽  
Mathew Gunshor ◽  
Szu‐Chia Moeller ◽  
Timothy J. Schmit ◽  
...  
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Water Vapor Absorption ◽  
Geostationary Satellites ◽  
Vapor Absorption

scholarly journals Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC<sup>4</sup>RS using bi-spectral reflectance measurements within the 1.88  µm water vapor absorption band

2016 ◽  
Vol 9 (4) ◽  
pp. 1743-1753 ◽  
Author(s):  
Kerry Meyer ◽  
Steven Platnick ◽  
G. Thomas Arnold ◽  
Robert E. Holz ◽  
Paolo Veglio ◽  
...  
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Near Infrared ◽  
Single Layer ◽  
Distinct Advantage ◽  
Cirrus Cloud ◽  
Water Vapor Absorption ◽  
Cloud Particle ◽  
Infrared Wavelength ◽  
Vapor Absorption

Abstract. Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or mid-wave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 µm water vapor absorption band, namely the 1.83 and 1.93 µm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the below-cloud water vapor absorption minimizes the surface contribution to measured cloudy top-of-atmosphere reflectance, in particular compared to the solar window channels used in heritage retrievals such as MOD06. This reduces retrieval uncertainty resulting from errors in the surface reflectance assumption and reduces the frequency of retrieval failures for thin cirrus clouds.

scholarly journals A Photoelectric Hygrometer*

1947 ◽  
Vol 28 (7) ◽  
pp. 330-334 ◽  
Author(s):  
Bernard Hamermesh ◽  
Frederick Reines ◽  
Serge A. Korff
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Absolute Humidity ◽  
Precipitable Water ◽  
The Other ◽  
Water Vapor Absorption ◽  
Absorption Bands ◽  
Vapor Absorption ◽  
Dispersing System ◽  
Humidity Range

An instrument that measures small absolute humidity changes by the photoelectric examination of the 9,440 Ångstrom-units absorption band of water vapor is described. The instrument consists of a small source of light which sends its radiation over an air path of less than one and a half meters to a dispersing system. The resulting spectrum then is allowed to fall on two vacuum phototubes; one centered in the 9,400 Ångstrom-units absorption band of water vapor, the other located at 8,000 ngstrom units where no water vapor absorption bands exist. As the absolute humidity in the air path is varied, the phototube in the region of the band is affected; whereas the reference phototube is not. The phototubes are arranged in an amplifying circuit so as to magnify the effect of varying humidity. The instrument uses a portable microammeter instead of the sensitive galvanometer of all previous spectral hygrometers. Humidity changes of 2 to 8 × 10−5 centimeter of precipitable water path over 143 centimeters of air path can be measured. An investigation of the small sensitive range of the instrument was carried out and the results indicate that the device is confined to use over a small humidity range with equipment available at the present time.

scholarly journals Cirrus cloud optical and microphysical property retrievals from eMAS during SEAC<sup>4</sup>RS using bi-spectral reflectance measurements within the 1.88 μm water vapor absorption band

2016 ◽  
Author(s):  
K. Meyer ◽  
S. Platnick ◽  
G. T. Arnold ◽  
R. E. Holz ◽  
P. Veglio ◽  
...  
Keyword(s):  
Water Vapor ◽  
Absorption Band ◽  
Near Infrared ◽  
Single Layer ◽  
Distinct Advantage ◽  
Cirrus Cloud ◽  
Water Vapor Absorption ◽  
Cloud Particle ◽  
Infrared Wavelength ◽  
Vapor Absorption

Abstract. Previous bi-spectral imager retrievals of cloud optical thickness (COT) and effective particle radius (CER) based on the Nakajima and King (1990) approach, such as those of the operational MODIS cloud optical property retrieval product (MOD06), have typically paired a non-absorbing visible or near-infrared wavelength, sensitive to COT, with an absorbing shortwave or midwave infrared wavelength sensitive to CER. However, in practice it is only necessary to select two spectral channels that exhibit a strong contrast in cloud particle absorption. Here it is shown, using eMAS observations obtained during NASA's SEAC4RS field campaign, that selecting two absorbing wavelength channels within the broader 1.88 μm water vapor absorption band, namely the 1.83 and 1.93 μm channels that have sufficient differences in ice crystal single scattering albedo, can yield COT and CER retrievals for thin to moderately thick single-layer cirrus that are reasonably consistent with other solar and IR imager-based and lidar-based retrievals. A distinct advantage of this channel selection for cirrus cloud retrievals is that the surface contribution to measured cloudy TOA reflectance is minimized due to below-cloud water vapor absorption, thus reducing retrieval uncertainty resulting from errors in the surface reflectance assumption, as well as reducing the frequency of retrieval failures for thin cirrus clouds.

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