Time schedule & content Recommended Books Motivation ...satellite.mpic.de/pdf_dateien/introduction_2012.pdf · Cambridge 2nd Edition, 1986. Eine (recht knapp formulierte) Übersicht

Remote sensing of the atmosphere [email protected] http://joseba.mpch-mainz.mpg.de/index.htm

Time schedule & content

Recommended Books

Motivation, General aspects of remote sensing

Historic overview

Remote Sensing of the Atmosphere

Lecture, Winter Semester 2012 / 13

Monday, 16:15, INF 229 / Room 120

Thomas WagnerInstitut für Umweltphysik, University of Heidelberg, Germany

Max-Planck-Institute for Chemistry, Mainz, Germany

Overview, history of remote sensing Physics and chemistry of the atmosphere Long path DOAS LIDAR, RADAR Passive Microwave observations Passive IR observations Ground based passive UV/vis/NIR observations Satellite / airborne UV/vis/NIR observations Practical training I: MAX-DOAS measurements Practical training II: MAX-DOAS data analysis

Time schedule & content


Books:

Spectroscopic methods:

Air monitoring by spectroscopic techniques, M.W. Sigrist, Ed., Chemical Analysis Series, 127, John Wiley & Sons, Inc, 1994. IUP 1489

Differential Optical Absorption Spectroscopy: Principles and Applications, Platt, Ulrich, Stutz, Jochen, Springer

The Remote Sensing of Tropospheric Composition from Space, John P. Burrows, Ulrich Platt, Peter Borrell Ed., Springer, http://www.ppmborrell.co.uk/RemoteSensingBook/

Script:

http://joseba.mpch-mainz.mpg.de/Atmremote.htm


Books:

Atmosphere:Physik unserer Umwelt, Die Atmosphäre, Walter Roedel, Thomas Wagner, Springer, Heidelberg, 4. Auflage, 2010, Eine Übersicht der physikalischen Prozesse in der Atmosphäre (IUP 1511, 1780)

More detailed lectures:The Physics of Atmospheres, J. T. Houghton, Cambridge University Press, Cambridge 2nd Edition, 1986. Eine (recht knapp formulierte) Übersicht der physikalischen Prozesse in der Atmosphäre von den Grundlagen bis zu Klimafragen.

Atmospheric Chemistry and Physics, J.H. Seinfeld and S.N. Pandis, John Wiley & Sons, Inc., 1998, Dickes Buch über Dynamik und Chemie von Troposphäre und Stratosphäre (IUP 1724).

The Chemistry of Atmospheres, R.P. Wayne, Oxford University Press, 1985. Beschäftigt sich überwiegend mit chemischen Aspekten, insbes. der Sauerstoff- und Ozonchemie (IUP 1512).


Remote sensing (From Wikipedia)

In the broadest sense, remote sensing is the measurement or acquisition ofinformation of an object or phenomenon, by a recording device that is not inphysical or intimate contact with the object.




In practice, remote sensing is the utilization at a distance (as from aircraft,spacecraft, satellite, or ship) of any device for gathering information about the environment. Thus an aircraft taking photographs, Earth observation andWeather satellites, monitoring of a fetus in the womb via ultrasound, andspace probes are all examples of remote sensing.





In modern usage, the term generally refers to techniques involving the use ofinstruments aboard aircraft and spacecraft rather than other fields which are considered to be under medical imaging or photogrammetry.





In modern usage, the term generally refers to techniques involving the use ofinstruments aboard aircraft and spacecraft rather than other fields which are considered to be under medical imaging or photogrammetry.

While all astronomy could be considered remote sensing (in fact, extremelyremote sensing) the term "remote sensing" is normally only applied toterrestrial observations.


Most remote sensing is performed using electromagnetic radiation

Interesting exceptions are:

-collecting dust from comets

-acoustic remote sensing (seismic, sonar, echo sounder)

-analysing particle radiation

-cosmic rays

-solar wind

…….


-On board: Geiger counter suited to measuring variations in particle radiation

-Explorer 1 repeatedly passed through a region in which the amount of radiation increased significantly.

-When Pioneer 3 was placed in a highly elliptical orbit in December 1958, it was determined that there were actually two peaks in counts as shown in the plot.

Explorer 1, on January 31, 1958, four months after the Soviet Union launchedSputnik I


-These zones of increased intensity proved to be due to trapped particles held in the Earth's magnetic field. Inner Van Allen Belt: protons from cosmic rays, Outer Van Allen Belt: electrons fromsolar wind.

-the Van Allen belts have for eons provided protection from these potentially devastating particle bombardments - a fact critical to the successful development of life on Earth;

-the Van Allen Belts become much weaker above 75°N and 75°S. This allows more particles toreach the the upper atmosphere and collide with oxygen, nitrogen and argon atoms in the air togenerate ions that in their excited states give off constantly moving, colorful, wavy displays known as polar lights


Two main radiation sources:

Using different platforms for (atmospheric) remote sensing


Using the electromagnetic spectrum for (atmospheric) remote sensing


Knowledge of atmospheric properties is important for:

-meteorology

-chemical composition (pollution, climate change)

-radiation budget (climate change)

-many regions of the atmosphere can not directly be reached (mainly in the vertical dimension)

-remote sensing typically integrates over extended volumes


Remote sensing of the atmosphere [email protected] http://www.mpch-mainz.mpg.de/satellite







Orbits and viewing geometries

Typical low polar orbits are used (~800km)

- the whole earth can be observed

- often sun-synchronous

- typical time for global coverage: 1 - 6 days

Geostationary orbits (~36000km)

-only part of the globe is covered

-typically coarser spatial resolution

-diurnal cycle is captured


Flight direction

Neighbouring orbits


Räumlich hochaufgelöste Messungen (20x40km²) von GOME

Mittlere PMD-Werte für April 2000 als RGB-Bild dargestellt


Echtfarbenbild der Bodenreflektivität von MODIS (räumliche Auflösung: 500 m)

http://modis.gsfc.nasa.gov/gallery


Remote sensing of the atmosphere [email protected] http://www.mpch-mainz.mpg.de/satellite310-377nm

Minimum reflectivity (earth without clouds) M. Grezeorski, IUP Heidelberg

Remote sensing of the atmosphere [email protected] http://www.mpch-mainz.mpg.de/satellite450-525 nm










What has happened to the solar photons?

‚Reflection‘ on the earth’s surface and upper ocean layer

Elastic scattering on molecules and aerosols (including cloud droplets)

Inelastic scattering (Raman scattering) on molecules

Absorption on aerosols

Absorption on molecules => Shows typically characteristic spectroscopic signatures

For long wavelengths (IR, MW, etc.) also emission


Brief history of remote sensing

With contributions from http://www.hao.ucar.edu/Public/education/Timeline.A.htmlhttp://observe.arc.nasa.gov/nasa/exhibits/history/history_1.html

1375 BC The oldest eclipse record is found on a clay tablet uncovered in the ancient city of Ugarit, (in what is now Syria), with two plausible dates usually cited: 3 May 1375 BC or 5 March 1223 BC, the latter being favoredby most recent authors on the topic. It is certainly clear that by the eight century BC, the Babylonians were keeping a systematic record of solar eclipses, and may even have been able to predict them fairly accurately based on numerological rules.


ca. 800 BC: The first plausible recorded sunspot observation

The two oldest records of a sunspot observation are found in the Book of Changes, probably the oldest extant Chinese book, compiled in China around or before 800 BC. The surviving sunspots records, though patchy and incomplete, covers nearly 2000 years and represents by far the most extensive pre-telescopic sunspot record.

P. Charbonneau and O.R. White, http://www.hao.ucar.edu/public/slides/slides.html

Large sunspots can be visible to the naked-eye under suitable viewing conditions, for example when the sun is partially obscured by clouds or mist, particularly at sunrise or sunset. In the West, the dominating views of Aristotle concerning the incorruptibility of the heavens meant that sunspots were "physically impossible", so that sightings were ignored or ascribed to transit of Mercury or Venus across the solar disk.


ca. 200 BC: The distance to the Sun

The first mathematically-based attempt at determining the Sun-Earth distance is due to Aristarchus ofSamos (ca. 310-230 BC). The procedure is illustrated on the diagram below; form a triangle by connecting the Earth (E), Sun (S) and Moon (M). At the first or third Moon quarter, the triangle so described in a right-angle triangle (a=90°). The angle b can be measured by an observer on Earth, which then allows the angle cto be computed (c=90-b when a=90°). The ratio of the Earth-Moon segment (EM) to the Earth-Sun segment (ES) is by definition equal to sin(c) (in modern trigonometric parlance; Aristarchus expressed this differently).

Aristarchus' geometric construction used to estimate the distance to the Sun. The Earth-Sun-Moon triangle and sizes are not drawn to scale.

While sound in theory, in practice this procedure is highly inaccurate in the Earth/Sun/Moon case; this is because EM is much smaller than ES, implying that b is very close to 90°, so that c is in turn very small. This has the consequence that a small measurement error on b translates in a large variation in the ratio EM/ES (again in modern parlance, a measurement error db is amplified by a factor 1/(sin c)2, which is large when c is very small). Aristarchus measured b=87°, while the true value is in fact 89° 50 minutes. This may seem a small error, but because of the large error amplification Aristarchus' value leads to EM/ES=19, instead of the true value EM/ES=397. Nonetheless, Aristarchus' calculation was the first to mathematically set the spatial scale of the cosmos.


968: The first mention of the solar corona

The solar corona is the hot, extended outer atmosphere of the Sun. It is far too faint to be seen against the blinding brightness of the solar disk itself, but becomes visible, and spectacularly so, at times of total solar eclipses when the solar disk is obscured by the Moon. While the solar corona is visible at any solar eclipse, the first explicit mention of what can be pretty ambiguously interpreted to be the corona was made by the Byzantine historian Leo Diaconus (ca. 950-994), as he observed the total eclipse of 22 December 968 from Constantinople (now Istanbul, Turkey). His observation is preserved in the Annales Sangallenses, and reads: "...at the fourth hour of the day ... darkness covered the earth and all the brightest stars shone forth. And it was possible to see the disk of the Sun, dull and unlit, and a dim and feeble glow like a narrow band shining in a circle around the edge of the disk".

http://www.mreclipse.com/SEphoto/SEgallery2/TSE94-123w.JPG http://cfa-www.harvard.edu/uvcs/GIF/LATEST.gif


1128: The first sunspot drawing

This drawing, from the Chronicles of John of Worcester (one of the many monks who contributed to the Worcester Chronicles), represents to the best of our knowledge the first surviving sunspot drawing, from a sighting on Saturday, 8 December 1128.

Sunspot drawing in the Chronicles of John of Worcester, twelfth century. Notice the depiction of the penumbra around each spot. Reproduced from R.W. Southern, Medieval Humanism, Harper & Row 1970, [Plate VII].


1185: The first description of solar prominences

Prominences are large accumulation of (relatively) cold gas held suspended high in the solar atmosphere by the Sun's magnetic field. Large prominences are often visible at times of solar eclipses, in the form of small reddish filaments or blobs in the lower corona. The first fairly unambiguous description of prominences is usually taken to be that found in the Russian Chronicle of Novgorod, in the following description of the 1 May 1185 solar eclipse: "In the evening there was an eclipse of the sun. It was getting very gloomy and stars were seen ... The sun became similar in appearance to the moon and from its horns came out somewhat like live embers."


1610: First telescopic observations of sunspots

In the first decade of the seventeenth century, four astronomers more or less simultaneously turned the newly invented telescope toward the Sun, and noted the existence of sunspots. They were Johann Goldsmid (1587-1616, a.k.a. Fabricius) in Holland, Thomas Harriot (1560-1621) in England, Galileo Galilei (1564-1642) in Italy, and the Jesuit Christoph Scheiner (1575-1650) in Germany.

Reproduction of one of Galileo's sunspot drawings. The umbrae/penumbrae structure is clearly depicted on this June 23 1612 drawing.


1666 Isaac Newton: Spectrum of sunlight

-sunlight from a small, circular hole falls on a prism, producing a rainbow of color. Although the production of a rainbow by a clear crystal was known to the ancients, it was Newton who showed that the colors did not originate in the crystal, but rather were components of sunlight. This array of colors he called a spectrum. "And so the true cause of the length of that image was detected to be no other, than that Light is not similar or homogenial, but consists of difform rays, some of which are more refrangible than others." Newton's experimental arrangement is shown in the image below. It is from Voltaire's Eléments de la Philosophie de Newton,published in 1738.

In addition, Newton was able to produce a spectrum from white light and then recombine the spectrum colors to get the white light back again. Years later, in Opticks, Query 29, he gave the following mechanism for the fact that the colors refracted from the greatest amount (violet) through blue, green, yellow, orange (which he does not mention) and to the least amount (red):

"Nothing is more requisite for producing all the variety of Colours, and degrees of Refrangibility than that the Rays of Light be Bodies of different Sizes, the least of which may take violet the weakest and darkest of the Colours, and be more easily diverted by refracting Surfaces from the right Course; and the rest as they are bigger and bigger, may make the stronger and more lucid colours, blue, green, yellow, and red, and be more and more difficultly diverted."


1675/76 Olaf (Ole) Roemer and Cassini: Speed of light

-variations in the calculated frequency of the planet Jupiter eclipsing its moon Io. To explain the variations, Cassini, in August 1675, writes:

"the second irregularity in the motion of the first Jupiter's satellite may be due to [the fact] that light takes some time to reach us from the satellite, and it takes from ten to eleven minutes to pass the distance equal to half the diameter of the Earth's orbit." In September 1676, Roemer announced that the November 9 eclipse of Io by Jupiter would occur 10 minutes later than that predicted. He was shown to be correct. In his paper on the speed of light, he never calculated the actual value. In 1983, writing the Journal for the History of Astronomy, Albert van Helden speculated, using clues in Roemer's paper, that the calculated value - had there been one - would have been around 135,000 km/sec.


1690, Christian Huygens Wave theoryIn 1690, Christian Huygens published his treatise on light in which the undulatory theory was expounded and explained. The general idea of the theory had been suggested by Robert Hooke in 1664, however, not in great detail. Up to that point in time, only three theories have been suggested about the mechanics of light.-Either the eye sent out something, which feels the object (as the Greeks believed);-or the object perceived sent out something which hits or affects the eye (as assumed in the emission theory);-or there was some medium between the eye and the object, and the object caused changes in the form or condition of this intervening medium affecting the eye (as Robert Hooke and Christian Huygens supposed in the wave or undulatory theory).According to this last theory space is filled with an extremely rare ether, and light is caused by a series of waves or vibrations in this ether, which are set in motion by the pulsations of the luminous body. From this third theory, Christian Huygens deduced the laws of reflection and refraction, explained the phenomenon of double refraction, and gave a construction for the extraordinary ray in biaxial crystals; while he found by experiment the chief phenomena of polarization.

Huygens Principle

A very general principle applying to all forms of wave motion which states that every point on the instantaneous position of an advancing phase front (wave front) may be regarded as a source of secondary spherical wavelets. The position of the phase front a moment later is then determined as the envelope of all the secondary wavelets (ad infinitum).


1777 Carl W. Scheele: effect of spectral colors on the darkening of silver chloride.

Carl W. Scheele (the discoverer of chlorine) investigated the effect of spectral colors on the darkening of silver chloride. It was already known that silver chloride darkened upon exposure to sunlight. Scheele found that, for the same exposure, the darkening was most rapid at the violet end.


1800 William Herschel, discovery of the infrared region

William Herschel, the famous astronomer, studied the heating effects of the colors of the spectrum. He did this by exposing thermometers to various colors of light. He found a steady increase in heating power going towards the red. He also used a thermometer placed just outside the red color as a control. To his amazement, the dark region just outside the red color provided even more heating power than the red color.

Herschel's experimental setup for the detection of invisible solar radiation. Sunlight passes through a prism (CD), forming the usual rainbow spectrum (E). A row of thermometers is positioned on a table (AB) beyond the red end of the spectrum. Thermometer 1, aligned with the spectrum, registers a rise in temperature, while the control thermometers 2 and 3 do not.


1801 Johann Wilhelm Ritter: discovery of the ultraviolet region

Johann Wilhelm Ritter verified Herschel's results and extended them. He placed silver chloride outside the violet end of the spectrum and found even more darkening than Scheele did 24 years earlier.


1801 Thomas Young: Explaining interference using wave theory

Interference patterns caused by light passing through a narrow slit. Up until this point, the wave theory of light (Huygens) had had nothing convincing to offer in opposition to the particle theory of light (Newton). Now it did, because you cannot explain interference using particles. However, using waves, it was easy. Here is what Young said in the Bakerian Lecture, November 29, 1801: "When two undulations, from different origins, coincide either perfectly or very nearly in direction, their joint effect is a combination of the motions belonging to both. "Since every particle of the medium is affected by each undulation, wherever the directions coincide, the undulations can proceed no otherwise then by uniting their motions, so that the joint motion may be the sum or difference of the separate motions, accordingly as similar or dissimilar parts of the undulations are coincident."


1802 William Wollaston: dark lines in the spectrum of sunlight

He passed sunlight through a very narrow slit (no more than 0.05 inch) so that it fell on the prism. (Up until this time, people had been using circular openings or relatively wide slits. This method resulted in very impure spectra.) Projecting the light over a distance of 10-12 feet, Wollaston saw red, yellowish-green, green, blue and violetcolors. He also reported seven dark lines. Five lines were reported as being on the boundries between twocolors, but two lines were within the color boundries (specifically yellowish-green and blue).

Wollaston's experimental setup for the prismatic observation of the solar spectrum. Wollaston believed that the lines labeled here B, C and E marked natural color boundaries, although he also noticed other dark lines (f,g) that did not appear to delineate colors. Reproduced from Philosophical Transactions of the Royal Society of London, vol. 92 (1802), p. 380 (Plate XIV).


1814-1823 Joseph von Fraunhofer: > 500 Fraunhofer lines in solar spectrum

Twelve years later, Joseph von Fraunhofer was looking for ways to check (and improve) the quality of telescopes he was making. He rediscovered the dark lines in the sun's spectrum while measuring the dispersive powers of various kinds of glass for light of different colors. As he worked on this project, he noticed that a bright 'orange' line (due to sodium, but he didn't know that) in the spectrum of the flame he was using was in the same position as the dark D-line (see below). This same line had been observed in flames from alcohol and sulfur as well as from candles. Fraunhofer mapped out the 574 thin black lines that he observed in the sun's spectrum. Eight of the most prominent lines were labeled A to G. Today, these lines are known as the Fraunhofer lines. The D-line was found to be two closely-spaced lines, subsequently called D1 and D2. Its position turned out to be in the yellow portion of the spectrum, not the orange that Fraunhofer wrote.

In 1821, Fraunhofer reported on his first efforts to use a diffraction grating (rather than a prism). Diffraction was discovered in 1665, but it received little attention until the early 1800s, when there was extensive discussion on the nature of light. Thediffraction grating, a series of closely spaced thin lines, was destined to play an important role in future discoveries. Using his early diffraction gratings, Fraunhofer was able to measure the wavelengths of the two sodium lines, obtaining values very close to the modern ones. However, he could not explain why the dark lines where there. In fact, although spectral research occupied him for much of his life, he never did find out how the lines that bear his name were made.


Briefmarke Bundespost 1987

(200. Geburtstag)

λ = Wellenlänge, g = Gitterkonstante, φ = Ablenkwinkel

Fraunhofer fertigte Beugungsgitter aus aufgespanntem Draht und mit Diamant geritzem Glas. Der Abstand der Furchen (Gitterkonstante) betrug nur 0,0033 mm!

Für einen Abstand von 50 cm: 0.15 mm pro nm (bei 500nm)


1815-1819 Augustin Fresnel: comprehensive treatment of the wave theory

Augustin Fresnel independently rediscovered interference and begins to study (and extend mathematically) the wave theory of light. In 1819, Fresnel publishes a 135-page comprehensive treatment of the wave theory of light, refuting completely the particle theory of light.

1832, David Brewster: Cause of Fraunhofer linesdark lines in the solar spectrum might be created by selective absorption of the light given off by the sun in its atmosphere. The obvious question then became which chemical substance absorbs which line or lines.

1833, William Miller: Dark lines also from laboratory gases- when sunlight is passed through gases in the laboratory, additional dark lines appeared in the sun's spectrum. It was suggested that the dark lines are due to the presence of gases on the sun. Miller also was one of the first to take photographs of spectra.

1834, Fox Talbot: Distinct fingerpring of substances- lithium and strontium, both of which give a red flame when burned. "the prism betrays between them the most marked distinction which can be imagined."

1840, John Herschel: Fraunhofer lines extended into the infrared

1849, Jean Foucault, Absorption line in arc lamp- in the spectrum of an arc between two carbon electrodes a line similar to the D line of the solar spectrum exists. He attempted to superimpose the two spectra by passing the sun's rays through the arc and then through the prism. This demonstrated that the lines were in the same place, since they superimposed on each other.


1859 The First Aerial Photographer

Gaspard Felix Tournachon, also known as Nadar, was a famous French photographer and balloonist who carried his bulky cameras aloft. His goal was to make land surveys from aerial photographs. Although Nadar set the stage for the future of remote sensing as we know it, he was not a success at aerial surveying. Hisphotographic observations did, however, catch the attention of the military. Nadar used this humorous card topromote his services.


1859 - 1862: Gustav Kirchhoff (a physicist) and Robert Bunsen (a chemist) relationship between the emission (bright-line) spectrum and the absorption (dark-line) spectrum

Spektralapparat as build by Gustav R. Kirchhoff and Robert W. Bunsen, around 1823. (© Chemical Achievers)

Kirchhoff passed sunlight of moderate intensity through a flame containing lithium chloride and observed the following: "One sees at the specific position [of the lithium line] a bright line on a dark background; for a greater intensity of incident sunlight, however, there appears at the same place a dark line, having exactly the same character as Fraunhofer's lines."Kirchhoff also used incandescent lime, which was known to give off a continuous spectrum. He passed the light from the lime through a sodium flame and then through a prism. In the exact position of the D line of the solar spectrum, there appeared a dark line.In this manner, he was able to demonstrate that hot gases absorbed the same wavelengths of light they emitted. He knew then that sodium vapormust be present in the atmosphere of the sun, absorbing the D line from the white light coming from the incandescent surface of the sun. He wrote: ". . . the dark lines of the solar spectrum, which are not caused by the earth's atmosphere, originate from the presence of those substances in the glowing solar atmosphere, which cause bright lines at the same place in the spectrum of a flame." However, with the lithium flame, a new line appeared between the B and C lines (remember these were labeled by Fraunhofer) that could not be associated with any of the known dark lines. Hence, no lithium was present in the sun's atmosphere.


Bunsen, Kirchhoff (Heidelberg, 1859)



Fraunhofer, München, 1814

“Im Augenblick bin ich und Kirchhoff mit einer gemeinsamen Arbeit beschäftigt, die uns nicht schlafen lässt. Kirchhoff hat nämlich eine wunderschöne und ganz unerwartete Entdeckung gemacht, indem er die Ursache der dunklen Linien im Sonnenspektrum aufgefunden und diese Linien künstlich ... hervorgebracht hat. Hierdurch ist der Weg gegeben, die stoffliche Zusammensetzung der Sonne und der Fixsterne mit derselben Sicherheit nachzuweisen, mit welcher wir Schwefelsäure, Chlor usw. durch unsere Reagentien bestimmen. Zur Erkennung mancher Stoffe ist diese Methode allen bisher bekannten vorzuziehen.”

Bunsen an Roscoe,15.11.1859

Bunsen, Kirchhoff (Heidelberg, 1859)

Lithium (Li) Natrium (Na) Kupfer (Cu) Strontium (Sr)

Gustav Robert Kirchhoff

1824 - 1887

in Heidelberg:

1854 - 1874

Robert Wilhelm Bunsen

1811 - 1899

in Heidelberg:

1852 - 1899

Das erste von Kirchhoff und Bunsen veröffentlichte SpektrumOben das Sonnenspektrum mit den Fraunhoferschen Linien, darunter die Spektren von Kalium, Natrium, Lithium, Strontium, Calcium und Barium.


1873 James Clerk Maxwell: Electromagnetism

unifying electricity and magnetism. He did this by showing that the two forces have a common origin. Since that time, we speak of electromagnetism. In his theory, it was clear that the emission of radiation by matter must be as a result of the acceleration of electric charges. It seemed that within matter there were mobile electrical charges that, as they moved in some fashion, produced the spectrum.

1879 Marie Alfred Cornu: First indication on atmospheric ozone

He found that the short wavelength limit of the solar radiation on the earth’s surface must be caused by an absorber located in the earth’s atmosphere.

1880 Sir Walther Noel Hartley: O3 absorption in the UV

He described the strong UV O3 absorptions between 200 and 300 nm and it became obvious that the absorbing properties of O3 fulfilled the requirements of that postulated atmospheric absorber. Further parts of the O3 absorption were discovered in the following years.

1880 J. Chappuis: O3 absorption in the visible

He discovered the much weaker visible absorptions (400 - 840 nm) in liquid ozone.

1890 Sir William Huggins: O3 absorption in the near UV

He discovered the highly structured O3 absorption between 300 and 360 nm in spectra of Sirius. Because of their characteristic absorption feature these ‘Huggins Bands’ as they are now called are well suited for the identification and quantification of atmospheric O3 absorptions in solar spectra


200 400 600 800Wavelength [nm]

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m]

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gins

Chappuis

310 330 3501E-22

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1880 Sir Walther Noel Hartley: O3 absorption in the UV

1880 J. Chappuis: O3 absorption in the visible

1890 Sir William Huggins: O3 absorption in the near UV


Spectra:

Greifswald, 8.9.2010

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Ozone absorption

1902 Leon Teisserenc de Bort and Richard Aßmann: Discovery of the stratosphere

They independently discovered that the atmospheric temperature starts to increase above about 10 km (In 1908 Teisserenc deBort called this layer between about 10 km and 50 km the stratosphere). This temperature increase was in agreement with the assumption of an absorbing (O3) layer at that altitudes.

1913 Niels Bohr: explanation of the hydrogen spectrum

Niels Bohr publishes an explanation of the hydrogen spectrum, which today we call "The Bohr Model of the Atom." In it, he uses the standard concepts of the time, but with a twist. He uses the "quantum hypothesis," introduced in 1900 by Max Planck and makes a critical assumption about how the lines in the spectrum are generated.

1913 Albert Wigand: O3 layer above 9 km

He concluded from balloon borne spectroscopic measurements over Berlin that the atmospheric ozone layer must be located above 9 km altitude.


1925 Gordon M.B. Dobson: Spectroscopic O3 measurements

Dobson developed a new very stable photospectrometer (double monochromator using quartz prisms) for the quantification of the atmospheric vertical column density (the vertically integrated concentration) of O3. Still today the ‘thickness’ of the atmospheric O3 layer is expressed as Dobson units (DU) which is the thickness (measured in 10-5 m) of the atmospheric O3vertical column density under normal conditions (1 DU equals 2.68 1016 molecules/cm²). Dobson spectrometers use a very simple (but very stable) spectroscopic method: the direct or scattered solar intensity is measured in different narrow (about 1 nm) spectral intervals which are located either in or outside of O3 (Huggins) absorption bands (see Fig.).

300 310 320 330 340 350Wavelength [nm]

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Different Dobson Wavelength Pairs

AB

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Fig. 6 Various wavelength pairs used for O3 observations of Dobson Photospectrometers. Also displayed is the O3absorption cross section in theHuggin bands. From the ratio of the measured intensities the atmospheric O3 column density is derived.

From the ratio of the radiation intensity of such wavelength pairs (and a geometric correction factor for the solar zenith angle, SZA) the vertical column density of O3 is determined. A possible influence on the intensity ratio due to the absorption of atmospheric aerosols can be accounted for by the combination of several wavelength pairs, for which the influence of O3 and aerosol is different.


World Dobson network

1 Dobson unit (DU): = height of 10 mat normal conditions

typical Thickness of the ozone layer: 350 DU(3.5 mm at normal conditions)

1926 Paul Götz: ozone profile observationPaul Götz investigated the variation of the intensity inside and outside ozone absorption bands during sunset. From the inversion of thisintensity ratio (the so called ‘Umkehr-Effect’) he concluded that the maximum of the ozone layer must be located around 25 km.

1929 Sidney Chapman: First photochemical theory of ozone layer The height profile of the atmospheric ozone layer was 1929 also confirmed by a (simple) photochemical theory involving only atmospheric oxygen introduced by Sidney Chapman at the first ozone conference at Paris.

1934 Erich Regener: First direct observation of the ozone layerHe was able to perform balloon flights into the stratosphere and he directly measured the UV absorption of the ozone layer.


1960 1970 1980 1990 2000

Sputnik

Satellites

Weather Satellites

Ozone(BUV)

Ozone(TOMS)

Ozone++(spectra)

UV/vis satellite history

Explorer

TIROS NIMBUS-4

NIMBUS-7

NOAA-9

NOAA-11 NOAA-14

Space shuttle

METEOR-3 Earth-probe

ADEOS

GOME SCIAMACHY

NIMBUS-7

GOME-2 ...

2010

SCIA OMI


Documents

Time schedule & content Recommended Books Motivation ...satellite.mpic.de/pdf_dateien/introduction_2012.pdf · Cambridge 2nd Edition, 1986. Eine (recht knapp formulierte) Übersicht