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STT and Tropopause Changes from Radar Windprofilers and Ozonesondes David W. Tarasick

STT and Tropopause Changes from Radar Windprofilers and Ozonesondes David W. Tarasick Air Quality Research Division, Environment Canada W.K. Hocking (UWO) T. Carey-Smith (NIWA). Walsingham.

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STT and Tropopause Changes from Radar Windprofilers and Ozonesondes David W. Tarasick

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  1. STT and Tropopause Changes from Radar Windprofilers and Ozonesondes David W. Tarasick Air Quality Research Division, Environment Canada W.K. Hocking (UWO) T. Carey-Smith (NIWA)

  2. Walsingham

  3. Radar signal power from the first Montreal campaign. Solid line shows the tropopause height derived from this data.

  4. Ozonesonde profiles from this campaign. White solid line = radar tropopause. The dashed lines indicate times when the tropopause undergoes rapid ascent.

  5. FLEXPART modeling seems to show good correspondence with apparent intrusions Driven by wind fields from the Canadian operational NWP model: GEM v3.2.0. North American regional grid, 0.5° x 0.5°, hourly, 58 levels.

  6. Almost every ozone intrusion follows a level 2 or 3 (0.3 – 0.4 km/hr) tropopause excursion. Every level 2 or 3 tropopause excursion is associated with an intrusion.

  7. The vertical gradient of the refractive index 2nd term in square brackets is generally ignored, as qis small above the lower troposphere. But, where there are sharp negative gradients of water vapour, can be much larger than and the term in q can dominate.

  8. Successive ozone and water vapor pressure profiles taken four hours apart on 19 August, 2004. Movement can be seen, as peak A moves to peak B.

  9. Conclusions • Stratospheric intrusions generally preceded by rapid changes in tropopause height • Quite common at midlatitudes (every 2-5 days) • Success of FLEXPART modeling suggests that GEM dynamics are quite good • Radar appears to be a particularly good intrusion detector • May be possible to follow the descent of layers of low humidity • Can we transfer this to Brewer total ozone changes?

  10. EXTRAS

  11. Continuing work… • CFCAS project GR-7042, "Impact of Large-Scale Stratospheric Ozone Intrusions on Operational Air Quality Forecast Model Applications” (Bourqui, Moran, McConnell, Jones, He, Osman) • New radars at Egbert, Sudbury, Eureka • Ozone data from Tropospheric Emission Spectrometer (TES) on the NASA Aura satellite • Several more ozonesonde campaigns with coordinated launches • Use of GEM-MACH • Operational GEM-based post-processing package for diagnosis of STE (Bourqui, Neary, Moran)

  12. Radar signal power from the first Walsingham campaign. Dashed line shows the tropopause height derived from this data.

  13. Ozonesonde profiles from this campaign..

  14. Modelling the intrusions • With FLEXPART - Written by Andreas Stohl • http://zardoz.nilu.no/~andreas/flextra+flexpart.html • A Lagrangian particle dispersion model • The model domain is filled with (millions of) particles. • Particles initially in the stratosphere are given an ozone concentration calculated using potential vorticity. • Ozone "parcels" are then advected with the model winds. • Wind fields from Canadian forecast model: GEM version 3.2.0 • North American regional grid. • 0.5 x 0.5 degrees, 58 levels, hourly.

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