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An updated analysis of stratospheric temperature trends

An updated analysis of stratospheric temperature trends. Contribution by Philippe Keckhut, Service d’Aéronomie/IPSL Chantal Claud, Laboratoire de Météorologie Dynamique/IPSL. Overview. lidar stations SSU characteristics comparisons SSU/lidars Solar effect. Lidars.

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An updated analysis of stratospheric temperature trends

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  1. An updated analysis of stratospheric temperature trends Contribution by Philippe Keckhut, Service d’Aéronomie/IPSL Chantal Claud, Laboratoire de Météorologie Dynamique/IPSL

  2. Overview • lidar stations • SSU characteristics • comparisons SSU/lidars • Solar effect

  3. Lidars Table 1. List of lidar stations used in this study

  4. SSU weighting functions AMSU weighting functions

  5. Comparisons for OHP + Hohenpeissenberg channel 26 (6 hPa)

  6. Comparisons for OHP + Hohenpeissenberg - channel 47X (0,5 hPa) ?

  7. Comparison for TMF - channel 27 (2 hPa)

  8. Comparison for Mauna Loa - channel 47X (0,5 hPa)

  9. Comparisons for La Réunion - channels 26 (6 hPa) and 47X (0,5 hPa) Oscillation at low altitude, not present at higher altitudes?

  10. Vertical trends TMF OHP

  11. TEMPERATURE CLIMATOLOGY AND TREND ESTIMATES OF THE UTLS REGION AS OBSERVED AT A SOUTHERN SUBTROPICAL SITE, DURBAN, SOUTH AFRICA H. Bencherif, et al., ACPD, 2006. Linear trend 70 hPa

  12. Temperature climatology above Dumont D’Urville (Antarctica) Keckhut et al. Nov-April Aug.-Oct. Occurrence of T < 190K ECMWF-RS at 100hPa for 1995-2000

  13. 79-2004 83-98 47X 27 26 25 15X MSU4 Cagnazzo et al., 2006

  14. The multi-parameter regressions (AMOUNTS)(Hauchecorne et al., 1991; Keckhut et al., 1995) • To evaluate temperature trends and variability (for data and model outputs): • It is necessary to parametrize the variability: • T(t) = m + St + A•Trend + B•Solar + C•QBO + D•ENSO + E•AO + Nt • The A, B, C, D, E terms represent the amplitude of trends / factors of variability; • (! Volcanic eruptions) • The residuals (AR(1)) include all the variability not considered in the parametrization. • The analysis of the residual terms : • model inadequacies • the degree of confidence of the analysis

  15. Les facteurs de variabilité de la température stratosphérique Solaire QBO(B. Naujokat) SOI Indice AO:Thompson and Wallace, 1998

  16. Response to the 11-year solar cycle US Rocket sites Tropics Sub-tropics Mid-latitudes Kekchut et al., 2005

  17. Response to the 11-year solar cycle Lidar 44°N Summer Winter Keckhut et al., 2005

  18. Response to the 11-year solar cycle ±70° 1979-1998 SSU at 6 hPa Keckhut et al., 2005

  19. Response to solar cycle • at low latitudes, photochemical response • at high and mid- latitudes, negative response with a strong seasonal dependence Role of the dynamics?

  20. Mechanistic simulations of the atmospheric solar response • Response depends on Planetary Waves activity • Response is highly non-linear 3D Rose/Reprobus model at SA Clim*1.5 Clim*1.8 Clim*2.2 Hampson et al., 2005

  21. Solar cycle/ conclusions • Equatorial response close to the photochemical response (1-2 K) • Negative response at mid and high latitudes with a strong seasonal effect • The solar response is strongly related to wave activity

  22. Concerning the future… • a new Phd student should work on trends from September 2006 on: methodology, temperature satellite retrievals, and trend updates. • Europeen project Geomon (IP, P.K. coordinator deputy): ground-satellite synergy for trend estimates (can be seen as a european contribution to SPARC). • work on solar influence on the low stratosphere: observations • ( FUB, MSU4, SSU) + Rose-Reprobus simulations. • - study of the solar influence using LMDz-Reprobus including an • interactive chemistry (a 20 years run is available) + extension to the mesosphere.

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