1 / 21

A.G. Feofilov 1,2 , A.A. Kutepov 1,2 , W.D. Pesnell 2 , and R.A. Goldberg 2

NON-LTE DIAGNOSTICS OF BROADBAND INFRARED EMISSIONS FROM MESOSPHERE AND LOWER THERMOSPHERE: APPLICATIONS TO SABER/TIMED. A.G. Feofilov 1,2 , A.A. Kutepov 1,2 , W.D. Pesnell 2 , and R.A. Goldberg 2. 1 – The Catholic University of America, Washington, DC, USA

gagan
Download Presentation

A.G. Feofilov 1,2 , A.A. Kutepov 1,2 , W.D. Pesnell 2 , and R.A. Goldberg 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NON-LTE DIAGNOSTICS OF BROADBAND INFRARED EMISSIONS FROM MESOSPHERE AND LOWER THERMOSPHERE: APPLICATIONS TO SABER/TIMED A.G. Feofilov1,2, A.A. Kutepov1,2,W.D. Pesnell2, and R.A. Goldberg2 1 – The Catholic University of America, Washington, DC, USA 2 - NASA Goddard Space Flight Center, Greenbelt, Maryland, USA 36th Annual European Meeting on Atmospheric Studies by Optical Methods August 17-22, 2009. Kyiv, Ukraine

  2. Outline • Broadband emission limb radiometry: advantages and disadvantages • LTE and non-LTE in molecular levels. • ALI-ARMS non-LTE research code. • SABER instrument onboard TIMED satellite. • Peculiarities of temperature, CO2, and H2O retrievals from SABER. • Conclusions.

  3. Broadband infrared emission limb radiometry • “Broadband“ here and below refers to the radiance in optical transitions of the molecular bands that covers both the fundamental and hot bands of the considered molecule. The typical spectral window is 100200 cm-1. • Advantages: • large signal-to-noise ratio. • both day- and nighttime measurements. • good latitudinal and longitudinal coverage. • Difficulties: • Non-LTE in molecular levels. • Uncertainties in parameters of rates involved in the model.

  4. LTE and non-LTE:two-level atomic gas example n2C21 = n1C12 R << C LTE R21n2 ~ R12n1 Otherwise - non-LTE !!!

  5. Energy exchange processes important forCO2 vibrational levels populations V-V

  6. Multi-level non-LTE problem nl Σ(Rll’+Cll’) = Σ nl’(Rl’l + Cl’l) + Pl Ll l’ l’ Σ nl = n l Lambda iteration J = Λ [S] Matrix method Accelerated Lambda Iteration (ALI) Λ = Λ* + (Λ - Λ*) ALI technique avoids expensive radiative transfer calculations for the photons trapped in the optically thick cores of spectral lines. Unsöld, 1920s Wintersteiner et al, 1992 Curtis & Goody, 1956 Lopez-Puertas et al, 1986 Rybicki & Hummer, 1991Kutepov et al., 1998

  7. CO model Other molecules: 2 350 viblevels CO, NO, N O, OH 2 200 000 lines O D 1 N and O 2 2 Electronic-Vibrational Energy Reservoir O /O photolysis 2 3 model H O model 2 43 viblevels 14 viblevels O model of O (X,A,B) 20 000 lines 3 2 23 viblevels 150 000 lines Current status of ALI-ARMS non-LTE model

  8. Applications of ALI-ARMS non-LTE code • Radiative cooling/heating rate calculations in the molecular bands in the atmospheres of: - Earth [Kutepov et al., 2007] - Mars [Hartogh et al., 2005]. • Analysis of satellite measurements: - CRISTA-1,2 [Kaufmann, 2002, 2003; Gusev 2006], - SABER [Kutepov et al., 2006; Feofilov et al, 2009].

  9. The SABER instrument aboard the TIMED satellite Latitudinal coverage TIMED: Thermosphere, Ionosphere, Mesosphere Energetics & DynamicsSABER: Sounding of the Atmosphere Using Broadband Emission Radiometry • Mission launched on December 7, 2001Data available since January 25, 20024 instruments: GUVI, SEE, TIDI, SABER • SABER instrument: • Designed to study the Mesosphere and Lower Thermosphere (MLT). • Limb scanning infrared radiometer. • 10 broadband channels (1.2717 µm) • Products: kinetic temperature, CO2, O3, H2O, NO, O2, OH, O, H.

  10. Bandpass functions ofSABER Temperature retrieval channels

  11. Peculiarities of non-LTE modelingExample 1:energy exchange among CO2 isotopes

  12. Energy exchange processes for 15m levels O VV O2 VT 15 m 15 m N2 CO2 Isotope 1 CO2 Isotope 2 Radiative excitation and de-excitation Collisional excitation and de-excitation Vibrational-translational (VT)energy exchange (N2, O2, O) Vibrational-vibrational (VV)energy exchange (CO2)

  13. Temperature retrieval from 15 m CO2 radiance

  14. Retrieval with modified SABER non-LTE model 02-JUL-2002

  15. Peculiarities of non-LTE modelingExample 2:adjusting rate coefficients for H2O retrievals

  16. Non-LTE model of H2O radiative transitions V-V, V-T processes O1D

  17. Uncertainties of V-V and V-T rate coefficients

  18. Updating the H2O non-LTE model • Selecting the correlative dataset that is not sensitive to non-LTE effects: ACE-FTS. • Identifying the set of rates that are important for 6.6m radiance calculation. • Performing the 7x3x3x40=2520 test runs for 40 overlapping mea- surements and calculating 2. • Minimum 2 corresponds to: • kV-V{H2O-O2}=1.2 x 10-12 cm3s-1kV-T{O2-O}=3.3 x 10-12 cm3s-1 • kV-T{H2O-M}=1.4 x current rates

  19. Retrievals with updated non-LTE model 2004 SE SS AE WS 2007 SS AE WS SE

  20. Conclusions • Broadband infrared molecular emission radiometry is a powerful technique that provides information about atmospheric temperature and composition up to lower thermosphere both for day and night conditions. • The analysis of this information requires complicated non-LTE models that describe all the processes governing the vibrational levels populations. • In some cases the reaction rates involved in non-LTE models need verification that can be done using nearly simultaneous measurements (or climatology) made by the instruments that are free of non-LTE effects (lidars, microwave, occultation technique).

More Related