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Upper stratospheric trends

This study examines upper stratospheric temperature trends using data from lidar and satellite sources. We focus on trend estimates from various stations including OHP and Hohenpeisenberg, revealing notable residual trends and cooling patterns between 1988 and 2005. The findings indicate large statistical uncertainties, particularly at Table Mountain, which shows significant cooling. We also discuss the implications of the 11-year solar cycle on temperature trends and recommend a reassessment of future trend assessments, emphasizing accuracy and temporal continuity.

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Upper stratospheric trends

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  1. Upper stratospheric trends Philippe Keckhut, Chantal Claud, Bill Randel

  2. Topics • lidar / SSU • Trend estimates • Other data sets • Solar effect

  3. NDACC Lidars

  4. OHP lidar has negligible residual trend Hohenp. lidar has positive residual trends: anomalies in 98-00 and biais ? TMF lidar has much larger cooling trends: step wise 2-3

  5. comparison of lidar and SSU trends for 1988-2005 Notes: Satellite trends are small for this period. Trends are changing Large statistical uncertainties for the lidars (only shown for OHP curve, but similar for other stations). Table Mountain is an outlier (strong cooling, as seen in the time series) Hohenpeisenberg also TMF. OHP. Hohenp.

  6. A new temperature trend assessment should • Assess trends • Time • Altitudes • Latitudes • Accuracy • trends accuracy • temporal continuity, data consensus • Highlighted what is new / 2001 • Trend behavior: • Changing trends • Existing series: • new, • combining (SSU/AMSU) • and stopping one (FUB, rocket) • What is required for future trends: recommendations

  7. Summer OHP Lidar temperature trends Linear 1979-1997 Linear 1979-2005 Linear term of a non linear analysis 1979-2005 Quadratic term 1979-2005

  8. Trends updated with rocket sondes 1969-1995 Rockets and lidar Heiss (81°N)

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

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

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

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

  13. 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

  14. Variations with Longitude 25 km 37 km 49 km Ref: Hampson et al. 2007

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