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Introduction to Atmospheric Transport and Chemistry

This lecture provides an introduction to the fundamental concepts in atmospheric dynamics, radiative transfer, stratospheric ozone chemistry, and the impact of solar variability on the middle atmosphere. It covers topics such as the Brewer-Dobson circulation, tropical tropopause, climate gases, solar radiation changes, and solar particles.

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Introduction to Atmospheric Transport and Chemistry

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  1. Atmospheric transport and chemistry lecture • Introduction • Fundamental concepts in atmospheric dynamics: Brewer-Dobson circulation and waves • Radiative transfer, heating and vertical transport • Stratospheric ozone chemistry • The tropical tropopause • Climate gases • Solar variability • The sun • Solar radiation changes and ozone • Solar particles and the middle atmosphere

  2. The sun seen in the visible (by MDI on the SOHO satellite)

  3. The sun seen in the visible (by MDI on the SOHO satellite)

  4. The sun seen in the visible (by MDI on the SOHO satellite) Planck‘s function (black-body radiation) deviation from Planck‘s function some structure

  5. Internal structure of the sun • The (assumed) zones within the sun: • core • radiative zone • convective zone • atmosphere

  6. The core of the sun All energy is produced in the solar core, by nuclear reactions (fusion reactions of H) Inner core: composed of 4He, no nuclear reactions Core edge: nuclear reactions of H, producing 4He

  7. Nuclear reactions at the core edge Proton-proton fusion chain to form 4He

  8. Nuclear reactions at the core edge Proton-proton fusion chain to form 4He Proton-carbon fusion chain to form 4He

  9. Relative abundances of species in the sun

  10. Relative abundances of species in the sun ... and in the solar system

  11. Relative abundances of species in the sun ... and in the solar system  the sun is formed of the debris of dead stars

  12. Nuclear reactions at the core edge Energy is released in the form of radiation ( - rays) .... and kinetic energy of the products

  13. The (assumed) zones within the sun: • core • radiative zone • convective zone • atmosphere

  14. Radiative zone Temperature and density are not large enough for nuclear reactions Radiation is transmitted from the core through the radiative zone – on it‘s way, it is absorbed and emitted many times, and loses energy

  15. Convective zone Formation of convection zells – cooled by updraft of ‚hot‘ plasma parcels  moving plasma produces a strong magnetic field (‚dynamo effect‘), similar to the formation of the terrestrial magnetic field

  16. The solar atmosphere Photosphere: ~ 1000 km small, forms the visible surface of the sun Chromosphere: several 1000 km Corona: several solar radii

  17. The solar spectrum – the spectrum of the solar atmosphere

  18. Temperature and density of the solar atmosphere Solar spectrum: black-body radiation of the photosphere

  19. Spectrum of the solar atmosphere: black body radiation, emission and absorption at different T and p Low T: only ground-state of atoms is occupied  absorption

  20. Spectrum of the solar atmosphere: black body radiation, emission and absorption at different T and p • Low T: only ground-state of atoms is occupied • absorption High T: excited-states are occupied  emission

  21. Spectrum of the solar atmosphere: black body radiation, emission and absorption at different T and p Low p: clearly defined lines High p: pressure broadening smears out lines

  22. Spectrum of the solar atmosphere: black body radiation, emission and absorption at different T and p broad absorption feature: cold, high density Clearly defined emission lines: hot, low density

  23. Temperature and density of the solar atmosphere broad absorption feature: cold, high density Clearly defined emission lines: hot, low density Density is constant within the corona !

  24. Spectrum of the solar atmosphere: black body radiation, emission and absorption in the solar atmosphere Fraunhofer lines in the far UV: emission from the chromosphere and corona

  25. Spectrum of the solar atmosphere: black body radiation, emission and absorption in the solar atmosphere Fraunhofer lines in the far UV: emission from the chromosphere and corona in the near-UV: absorption in the photosphere

  26. The photosphere – the visible surface of the sun granules across the solar surface: top of convection zells

  27. The photosphere – the visible surface of the sun Quiet sun Active sun dark sunspots in active regions

  28. The photosphere – the visible surface of the sun Quiet sun Active sun dark sunspots in active regions light faculae around active regions

  29. Sunspots and the solar 11-year (22-year) cycle Dark sunspots: cooler than the surrounding plasma

  30. Sunspots and the solar 11-year (22-year) cycle

  31. Sunspots and the solar 11-year (22-year) cycle • Sunspots are • colder than the surrounding plasma • associated with the solar magnetic field • extend into the chromosphere and corona as brighter areas

  32. Sunspots and the solar 11-year (22-year) cycle • Sunspots are • colder than the surrounding plasma  convection below sunspots is prohibited by the strong field • extend into the chromosphere and corona as brighter areas  plasma is trapped within the strong outer field

  33. The 11 – year sunspot cycle: the last 400 years Solar minimum: low sunspot numbers, low solar activity Solar maximum: high sunspot numbers, high solar activity Maunder minimum periodicity of 9 - 13 years

  34. Distribution of sunspots across the solar disk: the butterfly diagramm

  35. From the homepage of the Ulysses instrument (http://www.sp.ph.ic.ac.uk/~forsyth/reversals)

  36. From the homepage of the Ulysses instrument (http://www.sp.ph.ic.ac.uk/~forsyth/reversals)

  37. From the homepage of the Ulysses instrument (http://www.sp.ph.ic.ac.uk/~forsyth/reversals)

  38.  the 11-year solar cycle is a 22 year solar magnetic cycle ! From the homepage of the Ulysses instrument (http://www.sp.ph.ic.ac.uk/~forsyth/reversals)

  39. at the approach to solar max • the form of the corona changes • the brightness of the chromosphere increases • the surface of the chromosphere gets patchy

  40. The sun‘s corona during an eclipse (1966): solar magnetic field and the brightness of the corona From: Kivelson and Russell, Introduction to Space Physics

  41. Solar min: even surface Solar max: bright loops and dark patches across surface

  42. Loops: plasma trapped in closed magnetic field lines

  43. Closed loops in the solar magnetic field of the corona: prominences

  44. Closed loops in the solar magnetic field of the corona: prominences

  45. The final fate of a prominence: eruption

  46. Breaking and reconnection of the magnetic field lines above sunspots: solar coronal mass ejections flare associated with the CME large plasma bubble is hurled into space

  47. Breaking and reconnection of the magnetic field lines above sunspots: solar coronal mass ejections flare plasma bulb

  48. Evolution of a CME at the point where magnetic polarities change Low and Zhang, in: Solar variability and its effect on climate

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