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Retrieving Mars' Temperature Profile using IR Emission and Re-absorption

Explore methods for retrieving the temperature profile of Mars using infrared (IR) emissions and re-absorption. Learn about the challenges and various approaches, including physical methods like Chahine's method, statistical methods, and hybrid retrievals.

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Retrieving Mars' Temperature Profile using IR Emission and Re-absorption

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  1. PHY2505 - Lecture 14 IR temperature retrieval

  2. Line shape – altitude dependence Emission Re-absorption Z n

  3. 15um CO2 band and temperature of Mars 1 2 3 1 3 2

  4. Retrieval methods Even under cloud free conditions, with a noise free radiometer that measures all l, a unique solution for T(z) is not guaranteed With instrument noise and a limited number of l, an infinite numbers of solutions is possible. We want to find a temperature profile that satisfies the RTE and approximates the true profile as closely as possible

  5. Three classes of methods Physical methods: Chahine’s method – uses RTE & weighting functions & non-linear iteration (Liou 7.4.3.1) Statistical methods: no RTE (no physics!), regression between radiances and training set of temperature profile solutions - (Liou 7.4.3.2) Hybrid retrievals: – uses RTE and weighting functions and linearisation of the RTE to allow use of matrix inversion ( Liou 7.4.3.2)

  6. Physical methods

  7. Physical methods: Chahine’s method (Liou 7.4.3.1) Ii Ti(pi) Iterate the relaxation equation

  8. Chahine’s method – relaxation equation derivation (Liou 7.4.3.1) Liou equation 7.4.25a Approximate the observed radiance using the mean value theorem Dividing expected by observed: Can approximate by relaxation equation as low dependence on temperature

  9. Chahine’s method outline– (Liou 7.4.3.1)

  10. Chahine’s method outline– how good is it?

  11. Statistical methods – (Liou 7.4.3.2) First operational measurements

  12. Hybrid methods – (Liou 7.4.3.2)

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