Solar infra-red spectroscopy from high-altitude aircraft

1956 ◽  
Vol 236 (1205) ◽  
pp. 171-175 ◽  
Keyword(s):  
High Altitude ◽  
Water Vapour ◽  
Solar Spectrum ◽  
Ground Level ◽  
Small Region ◽  
Lower Atmosphere ◽  
Absorption Bands ◽  
Water Vapour Content ◽  
The Earth ◽  
Infra Red

The infra-red solar spectrum has been the subject of a fairly continuous study since the first elementary observations of Sir John Herschel in 1832. Figure 12 reproduces the solar spectrum recorded by Langley & Abbott in 1900, and this early record serves as an example to show that much of the sun’s incident energy fails to reach the earth. The main absorbing constituents of the atmosphere are water vapour and CO 2 , and these are the cause of the deep bands in the infra-red spectrum. In recent years other rearr gases, such as O 3 , HDO, CO, CH 4 and N 2 O, have been identified through their characteristic absorption bands. It is interesting to note that the HDO absorption band at 3·67 μ , first reported by Gebbie, Harding, Hilsum & Roberts in 1949, is clearly recorded in the Langley & Abbott spectrum, although with deuterium unknown it was impossible for them to identify it. The rarer constituents of the atmosphere have interested a number of experi­menters in more recent years and, for example, Shaw, Chapman, Howard & Oxholm (1951) have identified some 800 lines of atmphoseric origin in the small region between 3·0 and 5·2 μ . However, at ground level measurements are only possible where some solar energy reaches the earth. In order to make observations in the regions normally obscured it is necessary to reduce the amount of water vapour and carbon dioxide in the path by going to high altitude. The percentage CO 2 content of the atmosphere is approximately constant, and hence the amount of CO 2 between the sun and an observer will be reduced to one-half in going to 18000 ft. and to about one-tenth in going to 50000 ft. The water-vapour content falls off much more rapidly and measurements can be made in the 2·5 to 3·5 μ band by going to only 30000 ft. Migeotte & Neven (1952 a, b ) have made an attempt to overcome the effects of the denser lower atmosphere by making observations from the summit of the Jungfraujoch at a height of almost 12000 ft. By carrying a spectrometer in a modern aircraft it is possible to make detailed observations from heights greater than 50000 ft. A program of high-altitude spectroscopy is being undertaken jointly by the Gassiot Committee of the Royal Society and the Royal Aircraft Establishment, Farnborough. The purpose of the program is to record the solar spectrum out into the far infra-red from a Canberra aircraft flying at these heights.

An atlas of infra-red solar spectrum from 1 to 6.5μ observed from a high-altitude aircraft

1961 ◽  
Vol 254 (1037) ◽  
pp. 47-123 ◽  
Keyword(s):  
High Altitude ◽  
Water Vapour ◽  
Solar Spectrum ◽  
Absorption Lines ◽  
Infra Red

Records are presented of the infra-red solar spectrum from 1 to 6-5 /x, observed from altitudes up to 15 km. A resolution of about 1 cm-1 has been obtained over the whole region and 1200 absorption lines belonging to water vapour, C0 2 , CO, N 2 0 and CH 4 have been identified.

scholarly journals Ultra-violet transparency of the lower atmosphere, and relative poverty in Ozone

1918 ◽  
Vol 94 (660) ◽  
pp. 260-268 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Solar Spectrum ◽  
Ultra Violet ◽  
Lower Atmosphere ◽  
Atmospheric Ozone ◽  
Absorption Bands ◽  
Relative Poverty ◽  
Narrow Bands

Many years ago it was suggested by Hartley* that the limit of the solar spectrum towards the ultra-violet was attributable to absorption by atmospheric ozone, which, as he showed, would give rise to a general absorption beginning at about the place where the solar spectrum ends. In a recent paper by Prof. A. Fowler and myself,† the evidence for this view was very much strengthened. For it was shown that just on the limits of extinction the solar spectrum shows a series of narrow absorption bands which are eventually merged in the general absorption, and these narrow bands are precisely reproduced in the absorption spectrum of ozone. For my own part, I do not feel any doubt that ozone in the atmosphere is the effective cause limiting the solar spectrum.

scholarly journals An investigation of the absorption spectra of water and ice, with reference to the spectra of the major planets

1928 ◽  
Vol 120 (785) ◽  
pp. 296-302 ◽  
Keyword(s):  
Water Vapour ◽  
Absorption Spectra ◽  
Atomic Hydrogen ◽  
Solar Spectrum ◽  
High Dispersion ◽  
The Sun ◽  
Absorption Bands ◽  
Weak Band ◽  
General Similarity ◽  
Dense Band

The spectra of the light of the sun reflected from the major planets—Jupiter, Saturn, Uranus and Neptune—were photographed by Slipher in 1909. These spectra showed a general similarity in that there were a number of absorption bands superimposed on the ordinary solar spectrum. The intensity and width of these absorptions varied from planet to planet, increasing in general from Jupiter to Neptune in the order quoted. Of the chemical identity of the bands little is known. Some—C and F, fig. 4, for example—can be attributed to absorption by atomic hydrogen in the atmospheres of the planets; others might be due to water-vapour, though other water-vapour bands do not appear. The outstanding unidentified bands which are common to the spectra of the four planets are (see fig. 4, Plate 10):— ( a ) At λ = 5430 Å.—A rather weak band in the spectra of Jupiter and Saturn, but very strong in those of Uranus and Neptune. ( b ) At λ = 6190 Å.—This is the mid-point of a conspicuous and dense band appearing in the spectra of all the four planets, broadening from a width of some 50 Å in that of Jupiter to some 200 Å in that of Neptune. Although quite strong in the spectrum of Jupiter, it showed no tendency to become resolved in the high dispersion plates taken of the spectrum of this planet. ( c ) A strong double band at λ = 7200 to 7260 Å recorded in the spectra of Saturn and Jupiter, and probably just as strong in those of Uranus and Neptune, but not recorded because of the insensitiveness of the plates in this region.

Origin and distribution of the polyatomic molecules in the atmosphere

1956 ◽  
Vol 236 (1205) ◽  
pp. 187-193 ◽  
Keyword(s):  
Water Vapour ◽  
Ultra Violet ◽  
Ground Level ◽  
Absorption Bands ◽  
Ultra Violet Radiation ◽  
Low Concentrations ◽  
Vertical Distributions ◽  
Similar Accuracy ◽  
Lapse Rates ◽  
Made In

Of those gases which occur in the upper atmosphere and have strong absorption bands in the infra-red part of the spectrum and which must, therefore, be con­sidered when calculating the absorption and radiation of heat in the atmosphere, only carbon dioxide is uniformly mixed with the air at all heights which we are likely to be dealing with; it will not be considered further here. The vertical distributions of water vapour and ozone are of great interest, particularly when considered together. Water vapour, originating at ground level, usually decreases rather rapidly with increasing height, particularly in the lower stratosphere. This leads to extremely low concentrations at a height of about 15 km. On the other hand, ozone, being formed by the action of solar ultra-violet radiation at a height of 30 km or more, decreases in concentration downwards. We find, therefore, ozone diffusing downwards and water vapour diffusing upwards through the same region of the atmosphere, but, as we shall see, with very different lapse rates. Water vapour The standard hygrometers which are used to measure the humidity from free balloons are only satisfactory at temperatures above about 235°K, and our knowledge of the humidity at high levels in the atmosphere is almost entirely dependent on measurements made with frost-point hygrometers carried on air­craft. The work of the Meteorological Research Flight of the British Meteorological Office is notable for the very large number of measurements made from Mosquito aircraft to a height of about 12 km and more recently from Canberra aircraft to 15 km. Most unfortunately, hardly any measurements having similar accuracy have been made in other parts of the world. However, at the present time Dr A. W. Brewer is in north Norway making such measurements with the kind co-operation of the Norwegian Air Force and I had hoped that some results might have been available in time to report them at this Discussion (see note at end of paper).

scholarly journals VII. The influence of water in the atmosphere on the solar spectrum and solar temperature

1883 ◽  
Vol 35 (224-226) ◽  
pp. 328-341 ◽  
Keyword(s):  
Solar Spectrum ◽  
Absorption Bands ◽  
Atmospheric Absorption ◽  
Infra Red ◽  
Influence Of Water

In our paper on “Atmospheric Absorption in the Infra-red of the* Solar Spectrum” (“Proc. Roy. Soc.,” vol. 35, p. 80), we stated that the absorption by water coincided with the absorption bands to be found in the solar spectrum, and our proof rested in photographs which had been taken for some time back. In the diagram which we published (and in which are slight errors in shading at some parts, and which we here correct) we showed the coincidences as far as λ10,000, that being the limit to which we could accurately fix the wave-lengths.

scholarly journals Radiative equilibrium in the ionosphere

1947 ◽  
Vol 189 (1017) ◽  
pp. 218-240 ◽  
Keyword(s):  
Water Vapour ◽  
Atomic Oxygen ◽  
Ultra Violet ◽  
Negative Ions ◽  
Radiation Balance ◽  
Red Emission ◽  
The Earth ◽  
Infra Red ◽  
Absorption Agent ◽  
Gravitational Equilibrium

The equations of radiative equilibrium in the earth ’s atmosphere are examined with special reference to high temperatures in the ionosphere arising out of a radiation balance between heavy ultra-violet absorption in the ultra-violet and relatively weak infra-red emission. It is suggested that while molecular oxygen is the principal ultra-violet absorption agent at heights below 250 km., at greater heights the absorption is mainly due to atomic oxygen. Similarly, it is suggested that while water vapour is the principal infra-red radiator at a height of 100 km., at much greater heights water vapour is absent and the temperature is effectively controlled by negative ions at a height of 250 km. and perhaps by dust at much greater heights. The gravitational equilibrium of a dissociating oxygen atmosphere is discussed, reference being made to the effects of collisions and of absorption of the dissociating radiation.

AIS and Long Range Identification and Tracking

2005 ◽  
Vol 59 (1) ◽  
pp. 167-168
Author(s):  
F A Kingsley
Keyword(s):  
Radio Wave ◽  
Water Vapour ◽  
Long Range ◽  
Geometrical Optics ◽  
Significant Error ◽  
Lower Atmosphere ◽  
Line Of Sight ◽  
Water Vapour Content ◽  
Transmission Distance ◽  
Normal Water

There is a significant error in the equation referring to the rule of thumb for ‘line-of-sight’ analogue transmissions given in the paper by William Cairns, in the May 2005 issue (Cairns, 2005). This incorrect formula has previously been quoted in other sources, and possibly the author obtained it from one of these. In addition, the term ‘line-of-sight’ implies geometrical optics, whereas use of the term ‘radio horizon’ would be more appropriate since this takes account of the extension of radio wave transmission distance over the earth's surface caused by the normal water vapour content of the lower atmosphere over sea.

Atmospheric transmission in the 1 to 14 μ region

1951 ◽  
Vol 206 (1084) ◽  
pp. 87-107 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Water Vapour ◽  
Strong Dependence ◽  
Wave Length ◽  
Meteorological Conditions ◽  
Spectral Transmission ◽  
Atmospheric Transmission ◽  
Absorption Bands ◽  
Infra Red ◽  
Length Range

The transmission of the atmosphere for radiation of wave-lengths between 1 and 14 μ has been determined at sea-level, and its dependence on meteorological conditions investigated. Measurements have been made over paths of 2264 and 4478 yd., and the correlation with visibility and humidity studied in detail at four chosen wave-lengths, 2.18, 3.61, 10.01 and 11.48 μ ,. Spectral transmission curves for typical conditions have been recorded for the complete range 1 to 14 μ and, in addition to the numerous absorption bands due to water vapour arid carbon dioxide, some bands caused by the rarer constituents, in particular N 2 O and HDO, have been observed. Throughout the wave-length range investigated, the transmission varies with the visibility, the effect being less marked at the longer wave-lengths. For example, when, under typical conditions, the visual transmission falls from 75 to 50% per sea mile, the corresponding change at 2.18 μ is from 85 to 73%, and at 10.01 μ from 87 to 83%. At the latter wave-length there is a strong dependence on the quantity of water vapour in the path. Assuming that the observed variations of infra-red transmission with visibility are due to the scattering of radiation by salt nuclei the characteristics of a suitable size distribution have been calculated. As the humidity increases the nuclei absorb moisture and increase in size. The distribution is in agreement with the limited observations on size and concentration that have been reported. For a visual transmission of 40% per sea mile the radius of the most frequently occurring droplet is calculated to be 0.4 μ .

scholarly journals Integrated water vapour content retrievals from ship-borne GNSS receivers during EUREC<sup>4</sup>A

2020 ◽  
Author(s):  
Pierre Bosser ◽  
Olivier Bock ◽  
Cyrille Flamant ◽  
Sandrine Bony ◽  
Sabrina Speich
Keyword(s):  
Water Vapour ◽  
Weather Forecast ◽  
Global Navigation Satellite Systems ◽  
Water Vapour Content ◽  
Medium Range Weather Forecast ◽  
Satellite Systems ◽  
Infra Red ◽  
Integrated Water Vapour ◽  
Global Navigation Satellite ◽  
Gnss Data

Abstract. In the framework of the EUREC4A (Elucidating the role of clouds-circulation coupling in climate) campaign that took place in January and February 2020, integrated water vapour (IWV) contents were retrieved over the open Tropical Atlantic Ocean using Global Navigation Satellite Systems (GNSS) data acquired from three research vessels (R/Vs): R/V Atalante, R/V Maria S. Merian, and R/V Meteor. This paper describes the GNSS processing method and compares the GNSS IWV retrievals with IWV estimates from the European Center for Medium-range Weather Forecast (ECMWF) fifth ReAnalysis (ERA5), from the Moderate-Resolution Imaging Spectroradiometer (MODIS) infra-red products, and from terrestrial GNSS stations located along the tracks of the ships. The ship-borne GNSS IWVs retrievals from R/V Atalante and R/V Meteor compare well with ERA5, with small biases (−1.62 kg m−2 for R/V Atalante and +0.65 kg m−2 for R/V Meteor) and a root mean square (RMS) difference about 2.3 kg m−2. The results for the R/V Maria S. Merian are found to be of poorer quality, with RMS difference of 6 kg m−2 which are very likely due to the location of the GNSS antenna on this R/V prone to multipath effects. The comparisons with ground-based GNSS data confirm these results. The comparisons of all three R/V IWV retrievals with MODIS infra-red product show large RMS differences of 5–7 kg m−2, reflecting the enhanced uncertainties of this satellite product in the tropics. These ship-borne IWV retrievals are intended to be used for the description and understanding of meteorological phenomena that occurred during the campaign, east of Barbados, Guyana and northern Brazil. Both the raw GNSS measurements and the IWV estimates are available through the AERIS data center (https://en.aeris-data.fr/). The digital object identifiers (DOIs) for R/V Atalante IWV and raw datasets are https://doi.org/10.25326/71 (Bosser et al., 2020a) and https://doi.org/10.25326/74 (Bosser et al., 2020d), respectively. The DOIs for the R/V Maria S. Merian IWV and raw datasets are https://doi.org/10.25326/72 (Bosser et al., 2020b) and https://doi.org/10.25326/75 (Bosser et al., 2020e), respectively. The DOIs for the R/V Meteor IWV and raw datasets are https://doi.org/10.25326/73 (Bosser et al., 2020c) and https://doi.org/10.25326/76 (Bosser et al., 2020f), respectively.

Sign in / Sign up

Export Citation Format

Share Document