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Atmospheric chemistry and aerosols J .A.Pyle, Peter Braesicke, Glenn Carver,

Atmospheric chemistry and aerosols J .A.Pyle, Peter Braesicke, Glenn Carver, Fiona O’Connor and Guang Zeng Atmospheric Chemistry Modelling Support Unit Centre for Atmospheric Science Department of Chemistry University of Cambridge. Atmospheric chemistry and the earth system

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Atmospheric chemistry and aerosols J .A.Pyle, Peter Braesicke, Glenn Carver,

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  1. Atmospheric chemistry and aerosols J.A.Pyle, Peter Braesicke, Glenn Carver, Fiona O’Connor and Guang Zeng Atmospheric Chemistry Modelling Support Unit Centre for Atmospheric Science Department of Chemistry University of Cambridge

  2. Atmospheric chemistry and the earth system • Some modelling examples • Prospects for ESM with increasing computational capability

  3. SPM 3

  4. Clx T

  5. X X ‘Climate models’ Z Complexity of treatment ‘Models of intermediate complexity’ Interactions: chemistry/physics/biology atmosphere/ocean/surface/etc

  6. Developing (components of) an Earth System Model: Some atmospheric chemistry examples Tropospheric oxidizing capacity and air quality Some preliminary results Some added interactions (feedbacks) Stratospheric ozone Importance of interactions Increased complexity of treatment

  7. Tropospheric studies using the Met Office Unified Model • Composition changes in the past/future • Will chemistry/climate interactions affect these changes? • The Unified Model is a state-of-the art climate model • We have added a (fairly) detailed chemistry scheme for the troposphere • 46 species (Ox, HOx, NOx, CO/CH4/NMHC), 186 reactions (no halogens) • Surface emissions of NOx,NMHCs, etc are specified (SRes A2).

  8. 5 Experiments Atmosphere of 2000 with current emissions, etc. Emissions of NOx, NMHCs, etc, for 2100 from IPCC but into a ‘background’ 2000 atmosphere 2100 calculation with emissions as in B and an atmosphere with 2xCO2 In A-C the calculated O3 does not feedback onto climate, i.e. feedback loop is not complete D. 2000 atmosphere (as A) including O3 feedback E. 2100 atmosphere (as C) includingO3 feedback

  9. Schematic of the tropospheric ozone budget  Flux from stratosphere In situ chemistry RO2 + NO RO +NO2 NO2 + h  NO +O (+O2)  O3 O3 + h  O2 + O(1D) H2O + O(1D)  2OH  Surface deposition 

  10. The few model calculations so far suggest thatozone should increase in experiment B (i.e. 2100 - 2000, just considering chemical fluxes). They suggest asmaller ozone increase in expt C (i.e. 2100[including climate change] - 2000) BUT ..model budgets are very uncertain!! AND ..stratosphere usually a boundary condition

  11. O3 at surface (/ppbv) 2100-2000 (C-A) Note large increases in ozone over continents Some decreases over the oceans

  12. O3 (2100-2000)/ppbv Emission changes only (B-A) Plus climate change (C-A)

  13. O3 (ppbv) in 2100 between run C-B Vertical transport Transport and chemistry (lower T) Increased STE H2O-driven loss

  14. Adding O3 feedback (expts D & E) doesn’t change O3 much, but does change T - climate feedback?

  15. Longterm dynamical changes can cause stratospheric O3 variability and trends

  16. Very unusual O3 hole in 2002

  17. SH Wind/Ozone Scatter Plots for October 2002-like! Observations: Unified Model: Largest dynamic range in model when O3 feedback is included.

  18. NH Scatter Plot Full dynamic range requires variable SSTs

  19. ModelValidation with SONEX Data CO NOy O3 Graphs courtesy of Dominik Brunner, ETHZ From Marcus Koehler, Cambridge

  20. One-day advection using TOMCAT (T42L31) 3° S E S A S E S

  21. 0.5°

  22. One-day advection using p-TOMCAT (T106L44) 1° E S A S E S S

  23. Conclusions • Chemistry-climate interactions are important for troposphere and stratosphere. • Air quality set to detriorate & tropospheric ozone to increase this century • Future changes in the lower stratosphere appear to be very important - but this is sensitivity study and not final story. • O3 feedback to T looks important • Exciting prospect for high resolution studies

  24. Ozone vertical profiles

  25. Model budgets from IPCC

  26. ∆O3 from IPCC, various models

  27. Ozone seasonal behaviour

  28. Lower stratosphere cools by a few K - impact on kinetics OH + NO2 + M  faster OH + HNO3  faster Should reduce HOx, the main O3-destroyer in the very low stratosphere

  29. Tropospheric ozone budgets/Tg/yr $, production and destruction *, tropospheric burden in Tg

  30. O3 (2100-2000)/ppbv (Contours emphasize stratosphere) Increase in lower strat B-A Larger increase in lower strat  partly due to -T there in future climate C-A

  31. Approx. observed T Observed T consistent with changed ozone, CO2, etc

  32. X Z Complexity of treatment Y Interactions: chemistry/physics/biology atmosphere/ocean/surface/etc

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