Albedo is the measure of the diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body. It is dimensionless and measured on a scale from 0 to 1.
Spectroscopy is the study of the interaction between matter and electromagnetic radiation. Historically, spectroscopy originated through the study of visible light dispersed according to its wavelength, by a prism. Later the concept was expanded greatly to include any interaction with radiative energy as a function of its wavelength or frequency, predominantly in the electromagnetic spectrum, though matter waves and acoustic waves can also be considered forms of radiative energy; recently, with tremendous difficulty, even gravitational waves have been associated with a spectral signature in the context of LIGO and laser interferometry. Spectroscopic data are often represented by an emission spectrum, a plot of the response of interest as a function of wavelength or frequency.
An aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. Aerosols can be natural or anthropogenic. Examples of natural aerosols are fog, dust, forest exudates and geyser steam. Examples of anthropogenic aerosols are haze, particulate air pollutants and smoke. The liquid or solid particles have diameters typically <1 μm; larger particles with a significant settling speed make the mixture a suspension, but the distinction is not clear-cut. In general conversation, aerosol usually refers to an aerosol spray that delivers a consumer product from a can or similar container. Other technological applications of aerosols include dispersal of pesticides, medical treatment of respiratory illnesses, and convincing technology. Diseases can also spread by means of small droplets in the breath, also called aerosols.
A microwave radiometer (MWR) is a radiometer that measures energy emitted at millimetre-to-centimetre wavelengths known as microwaves. Microwave radiometers are very sensitive receivers designed to measure thermal electromagnetic radiation emitted by atmospheric gases. They are usually equipped with multiple receiving channels in order to derive the characteristic emission spectrum of the atmosphere or extraterrestrial objects. Microwave radiometers are utilized in a variety of environmental and engineering applications, including weather forecasting, climate monitoring, radio astronomy and radio propagation studies.
A nephelometer is an instrument for measuring the concentration of suspended particulates in a liquid or gas colloid. A nephelometer measures suspended particulates by employing a light beam and a light detector set to one side of the source beam. Particle density is then a function of the light reflected into the detector from the particles. To some extent, how much light reflects for a given density of particles is dependent upon properties of the particles such as their shape, color, and reflectivity. Nephelometers are calibrated to a known particulate, then use environmental factors (k-factors) to compensate lighter or darker colored dusts accordingly. K-factor is determined by the user by running the nephelometer next to an air sampling pump and comparing results. There are a wide variety of research-grade nephelometers on the market as well as open source varieties.
The planet Jupiter has a system of rings known as the rings of Jupiter or the Jovian ring system. It was the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed in 1979 by the Voyager 1 space probe and thoroughly investigated in the 1990s by the Galileo orbiter. It has also been observed by the Hubble Space Telescope and from Earth for several years. Ground-based observation of the rings requires the largest available telescopes.
Palagonite is an alteration product from the interaction of water with volcanic glass of chemical composition similar to basalt. Palagonite can also result from the interaction between water and basalt melt. The water flashes to steam on contact with the hot lava and the small fragments of lava react with the steam to form the light colored palagonite tuff cones common in areas of basaltic eruptions in contact with water. An example is found in the pyroclastic cones of the Galapagos Islands. Charles Darwin recognized the origin of these cones during his visit to the islands. Palagonite can also be formed by a slower weathering of lava into palagonite, resulting in a thin, yellow-orange rind on the surface of the rock. The process of conversion of lava to palagonite is called palagonitization.
Chemically, black carbon (BC) is a component of fine particulate matter. Black carbon consists of pure carbon in several linked forms. It is formed through the incomplete combustion of fossil fuels, biofuel, and biomass, and is emitted in both anthropogenic and naturally occurring soot.
The Angstrom exponent or Ångström exponent is a parameter that describes how the optical thickness of an aerosol typically depends on the wavelength of the light.
An Atmospheric radiative transfer model, code, or simulator calculates radiative transfer of electromagnetic radiation through a planetary atmosphere, such as the Earth's.
Ocean turbidity is a measure of the amount of cloudiness or haziness in sea water caused by individual particles that are too small to be seen without magnification. Highly turbid ocean waters are those with a large number of scattering particulates in them. In both highly absorbing and highly scattering waters, visibility into the water is reduced. The highly scattering (turbid) water still reflects a lot of light while the highly absorbing water, such as a blackwater river or lake, is very dark. The scattering particles that cause the water to be turbid can be composed of many things, including sediments and phytoplankton.
The Umkehr is the time variation of the ratio of the scattered intensity at two different wavelengths. The word means 'reversal' in German. The Umkehr effect is observed when measurements are made with ultraviolet spectrophotometer of the ratio of the zenith sky light intensities of two wavelengths in the solar ultraviolet when the sun is near the horizon. The shorter of two wavelengths (intensity I) is strongly absorbed and other (intensity I' ) is weakly absorbed. If the value of log(I/I' ) is plotted against the sun's zenith angle, it is observed that this log-intensity ratio decreases as the zenith angle increases until a minimum is reached for a zenith angle of about 80 (when the wavelengths are 3114 and 3324 A0). This effect was first noticed by Götz in 1930. The Umkehr measurement is known as customarily N-value and is given by the logarithm base 10 of the ratio of cloudless zenith sky intensitities at two different wavelengths scaled by a multiplicative factor 100 plus a constant which depends on instruments and extraterrestrial radiation. Methods for deriving vertical distribution from the umkehr measurements were developed by Götz, Dobson and Meetham in 1934, using the Dobson ozone spectrophotometer developed by Gordon Dobson. In 1964 Carlton Mateer provided analysis on information content in umkehr measurements.
Seismic inversion involves the set of methods which seismologists use to infer properties through physical measurements. Surface-wave inversion is the method by which elastic properties, density, and thickness of layers in the subsurface are obtained through analysis of surface-wave dispersion. The entire inversion process requires the gathering of seismic data, the creation of dispersion curves, and finally the inference of subsurface properties.
A closure experiment in atmospheric science is a combination of different measurement techniques to describe the current state of the investigated system as fully as possible, and to find inaccuracies in one or some of the methods involved. The comparison of different types of measurement often involves model calculations, which may also be tested in this process.
OSIRIS is an instrument that measures vertical profiles of spectrally dispersed, limb scattered sunlight from the upper troposphere into the lower mesosphere. OSIRIS is one of two instruments on the Odin satellite, launched February, 2001 into a sun-synchronous, 6 pm/6 am local time orbit at 600 km. This restricts OSIRIS sunlit observations to the Northern hemisphere in May, June, July August and the Southern hemisphere in November, December, January and February. Global coverage from 82°S to 82°N occurs on the months adjoining the equinoxes. OSIRIS measurements began November, 2001 and continue to the present.
Water Remote Sensing studies the color of water through the observation of the spectrum of water leaving radiation. From the study of this spectrum, the concentration of optically active components of the upper layer of the water body can be concluded via specific algorithms. Water quality monitoring by remote sensing and close-range instruments has obtained considerable attention since the founding of EU Water Framework Directive.
Atmospheric lidar is a class of instruments that uses laser light to study atmospheric properties from the ground up to the top of the atmosphere. Such instruments have been used to study, among other, atmospheric gases, aerosols, clouds, and temperature.
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Dubovik, O. and M. D. King, 2000: A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements, J. Geophys. Res., 105, 20 673-20 696.
Dubovik, O., A. Sinyuk, T. Lapyonok, B. N. Holben, M. Mishchenko, P. Yang, T. F. Eck, H. Volten, O. Munoz, B. Veihelmann, W. J. van der Zande, J-F Leon, M. Sorokin, and I. Slutsker, 2006: Application of spheroid models to account for aerosol particle nonsphericity in remote sensing of desert dust. J. Geophys. Res., 111, doi : 10.1029/2005JD006619.
