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Ross Salawitch 1 , Ben Johnson 1 , Doug Kinnison 2 , Martyn Chipperfield 3

Evaluation of the Chemical Mechanism within CCMs using a constrained Photochemical Steady State (PSS) Model. Ross Salawitch 1 , Ben Johnson 1 , Doug Kinnison 2 , Martyn Chipperfield 3 1 University of Maryland; 2 NCAR; 3 University of Leeds

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Ross Salawitch 1 , Ben Johnson 1 , Doug Kinnison 2 , Martyn Chipperfield 3

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  1. Evaluation of the Chemical Mechanismwithin CCMs using a constrainedPhotochemical Steady State (PSS) Model • Ross Salawitch1, Ben Johnson1, Doug Kinnison2, Martyn Chipperfield3 • 1University of Maryland; 2NCAR; 3University of Leeds • Will be delighted to work with CCM Investigators to help resolve discrepancies: • rjs@atmos.umd.edu • Work relies entirely on the T3I files submitted to the archive • Material posted at http://www.atmos.umd.edu/~rjs/ccmval/ • CCM community emailed above URL (and description of this work) • week prior to this meeting CCMVal Workshop, Toronto 2 June 2009

  2. Evaluation of the Chemical Mechanismwithin CCMs using a constrainedPhotochemical Steady State (PSS) Model • This work builds on methods developed for NASA Models and Measurements I & II • evaluations •  included mainly 2D models but some 3D models • Process for evaluation of chemical mechanism: •  designed during breakouts at “Process-orientated validation of coupled- • chemistry climate models” workshop, Grainau, Germany, Nov, 2003 •  described in Eyring et al. (BAMS, 2005) •  facilitated by design of the T3I file specifications (a lot of email and phone calls • between Doug and Ross, and between Doug and many others) • First public “unveiling” of PSS Chem Mech Eval, due to confluence of: •  availability of “core dumps” (T3I) files from many models •  sufficient lead time, commitment, and “gentle prodding” to transfer more than • 600 Gb of info to our home computers and develop software to interface • files from each group (which differ in subtle ways!) to our PSS model • has been “straightforward” but certainly not “easy” 

  3. Long-lived radical precursors: O3, H2O, CH4, CO, NOy, Cly, Bry Chemical Mechanism Computes: O(3P), O(1D), OH, HO2, NO, NO2, ClO, BrO, etc Physical properties of atmosphere: p, T, aerosol surface area, overhead O3 Solar Declination, Latitude, Longitude Once we know: O(3P), O(1D), OH, HO2, NO, NO2, ClO, BrO, etc Compute: dO3/dt terms, etc Chemical Mechanism

  4. Long-lived radical precursors: O3, H2O, CH4, CO, NOy, Cly, Bry Chemical Mechanism Computes: O(3P), O(1D), OH, HO2, NO, NO2, ClO, BrO, etc Physical properties of atmosphere: p, T, aerosol surface area, overhead O3 Solar Declination, Latitude, Longitude Chemical Mechanism Contend: If all models are using “JPL 2006” kinetics, which defines their chemical mechanism, then all models should compute the same values of O(3P), OH, NO, ClO, BrO, etc for the same specification of long-lived radical precursors & physical properties

  5. Long-lived radical precursors: O3, H2O, CH4, CO, NOy, Cly, Bry Chemical Mechanism Computes: O(3P), O(1D), OH, HO2, NO, NO2, ClO, BrO, etc Physical properties of atmosphere: p, T, aerosol surface area, overhead O3 Solar Declination, Latitude, Longitude Chemical Mechanism Contend: If all models are using “JPL 2006” kinetics, which defines their chemical mechanism, then all models should compute the same values of O(3P), OH, NO, ClO, BrO, etc for the same specification of long-lived radical precursors & physical properties How to test? In Grainau (Nov 2003), we stated that definition of long-lived radical precursors and physical properties of the atmosphere from zonal monthly mean sampling of a CCM could be used as input to a well established chemical model, which if run in photochemical steady state (PSS) over a full diel cycle (integrated PL =0 for all species), would result in 24 hr avg’d profiles of radicals that should closely approximate the zonal monthly mean profiles of radicals from the CCM

  6. Long-lived radical precursors: O3, H2O, CH4, CO, NOy, Cly, Bry Chemical Mechanism Computes: O(3P), O(1D), OH, HO2, NO, NO2, ClO, BrO, etc Physical properties of atmosphere: p, T, aerosol surface area, overhead O3 Solar Declination, Latitude, Longitude Chemical Mechanism Contend: If all models are using “JPL 2006” kinetics, which defines their chemical mechanism, then all models should compute the same values of O(3P), OH, NO, ClO, BrO, etc for the same specification of long-lived radical precursors & physical properties How to test? In Boulder (Oct 2005), we discussed the file specification needed to carry out this task Since then, Doug Kinnison has been instrumental in implementing the specifications of the T3I files needed to carry out these comparisons

  7. PSS Model Comparisons: T3I files † O3 and T from WACCM above 3.55 hPa used for J value computation * sad_sulf from WACCM used for analysis

  8. PSS Model Comparisons: T3I files

  9. A Few More Details • Focus on periods of time when atmospheric observations are available • Will examine: • a) profiles of radical precursors • b) “tracer – tracer” relations of radical precursors • c) CCM vs PSS radical profiles • For radicals, the comparison is between 24 hour average output of the PSS • model versus the ZMM of the CCM model • If the chemistry is properly represented in both models, this comparison • should look very good (but will not be perfect!) • Powerful method to diagnose representation of fast chemistry in models • Initial focus on 35N, Sept 1993: • a) time of high aerosol loading • b) atmosphere sampled by a high altitude balloon flight that • resulted in many papers documenting atmospheric composition • (e.g., Osterman et al., GRL, 1997) • Have also examined 22N, Feb 1996: • a) measurement of HOx, NOx, ClO & precursors in the tropical UT/LS region • b) focus of Wennberg et al. (Science, 1998) and numerous other papers

  10. WACCM Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause

  11. CAM 3.5 Model lid at 3.5 hPa might be affecting transport for species such as N2O Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Bry low Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause

  12. CMAM Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause

  13. CNRM-ACM Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean Very Cold Tropopause CCM Tropopause Cly present in troposphere Bry present in troposphere

  14. GEOS CCM Low Tropopause Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause

  15. MRI Low Tropopause Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Bry high Bry present in troposphere

  16. UMSLIMCAT Low Tropopause Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Model Output Not Available For p > 170 hPa Bry high: a VSL bromocarbon source of ~6 ppt was used in this run

  17. CCSR NIES Model & data for 1985; T3I files for 1993 unavailable Upper Strat Cly April 1985 Upper Strat Bry April 1985 Cly very high Bry very high Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean O3 high CCM Tropopause Scale Change Scale Change

  18. WACCM Woodbridge and Wamsley Relns Scaled to Sept 1993

  19. WACCM Bry differs because Wamsley Reln considers CH2Br2, which is known to reach the stratosphere

  20. CAM 3.5 Woodbridge and Wamsley Relns Scaled to Sept 1993 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean Model lid at 3.5 hPa might be affecting transport for species such as N2O Bry low

  21. CMAM Bry differs because Wamsley Reln considers CH2Br2, which is known to reach the stratosphere HTOT slightly low

  22. CNRM-ACM Bry differs because Wamsley Reln considers CH2Br2, which is known to reach the stratosphere HTOT high: puzzling due to very cold tropopause

  23. GEOS CCM Cly slightly low Bry slightly low, even considering neglect of CH2Br2

  24. MRI Cly slightly high Bry very high

  25. UMSLIMCAT Bry high: a VSL bromocarbon source of ~6 ppt was used in this run

  26. CCSR NIES Model & data for 1985; T3I files for 1993 unavailable Scale Change Scale Change O3 high HTOT very low Scale Change Cly very high Bry very high

  27. WACCM There is a red line under the black  There is a red line under the black  There is a red line under the black  As good as it gets ! If we are actually solving the same set of chemical reactions, as we aspire, then all comparisons should look nearly this good 

  28. CAM 3.5 Looks good. Would like to examine O(3P) and determine whether BrONO2+O rxn is included in model Suspect BrONO2+O rxn, new for JPL-06, has not been added  Diff in BrO consistent with diff in NOx Diff in ClO consistent with diff in NOx NOx a little low compared to PSS

  29. CMAM Looks great! Would like to examine O(3P) and O(1D) and re-evaluate once sulfate SA file from CMAM is submitted Have confirmed BrONO2+O rxn, new for JPL-06, has not been included !

  30. CNRM-ACM Looks good; would like to determine whether “PSC chemistry” has been “turned off” for extra-polar regions and whether BrONO2+O rxn is included in model. ClOx in PSS activated due to PSC like T Relevant chemistry must be “turned off” in CCM Looks like BrONO2+O not added  NOx in PSS near zero due to PSC like T Relevant chemistry must be “turned off” in CCM Scale Change

  31. GEOS CCM Looks good. However, the chemical mechanism in this model seems to over-estimate ClO and under-estimate BrO. Would like to run with GEOS sulfate surface area. BrO not imp. at high alt BrO slightly low ClO slightly high Looks like BrONO2+O not added  Has ClO+OH  HCl been added ?!?

  32. MRI O(3P) file not submitted O(1D) file not submitted HOx low The chemical mechanism used in this model seems to differ from PSS in important manners. Would like to run with MRI sulfate surface area; however, this will not affect comparisons for p < ~20 hPa. BrO low ClO high NOx low Scale Change

  33. UMSLIMCAT O(3P) file not submitted O(1D) file not submitted HOx offset consistent with NOx Looks great. Would like to examine O(3P), O(1D), BrO, and run with UMSLIMCAT sulfate surface area. BrO file not submitted; have to compare BrO+Br Difference inconseq.; BrO does not matter at high altitude NOx slightly lower than PSS, perhaps due to surface area mismatch ClO offset consistent with NOx Scale Change

  34. CCSR NIES Model & data for 1985; T3I files for 1993 unavailable HOx low throughout lower stratos The chemical mechanism used in this model may differ from PSS in important manners. Would like to examine O(3P) and (O1D), and model output for latter years, when sulfate chemistry becomes more important. NOx low in lowermost stratosphere Diff in ClO consistent with diff in NOx Looks like BrONO2+O not added 

  35. Next Steps • Compute “error bar” for PSS model values of O(3P), O(1D), HOx, NOx/NOy, • ClO/Cly, and BrO/Bry by propagating variance, about the zonal monthly • mean, of inputs to the PSS model that are derived from each CCM model: • i.e., we will formally evaluate how computed variance T, sulfate SA, O3, • H2O, CH4, CO, NOy, Cly, Bry impacts the computed radicals • Update comparisons as: •  additional models submit T3I files •  additional files (i.e., sulfate SA, O3P, O1D) are submitted for the • nine models that have submitted files • Run additional cases: •  Feb 1996 (NASA STRAT Flights) has been run (included in this PPT) •  we are open to suggestion for periods of particular interest • Submit PSS J values to photocomp !!! • This is a work in progress … hopefully of some value to CCMVal  • We will gladly provide detailed PSS model output, upon request, to groups • who are interested in diagnosing the reasons for differences between • radical fields computed by their CCM and the PSS model • We’ll develop “grades” based on these comparisons upon request 

  36. Comparisons for 22N, Feb 1996 to follow

  37. WACCM Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Upper Strat Cly Feb 1996

  38. CAM 3.5 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Model lid at 3.5 hPa might be affecting transport for species such as N2O Upper Strat Cly Feb 1996

  39. CMAM Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Upper Strat Cly Feb 1996

  40. CNRM-ACM Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Upper Strat Cly Feb 1996

  41. GEOS CCM Low Tropopause Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Upper Strat Cly Feb 1996

  42. MRI Low Tropopause Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Upper Strat Cly Feb 1996

  43. UMSLIMCAT Low Tropopause Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean CCM Tropopause Model Output Not Available For p > 170 hPa Upper Strat Cly Feb 1996

  44. WACCM Woodbridge and Wamsley Relns Scaled to Feb 1996

  45. WACCM Bry differs because Wamsley Reln considers CH2Br2, which is known to reach the stratosphere

  46. CAM 3.5 Woodbridge and Wamsley Relns Scaled to Feb 1996 Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean Model lid at 3.5 hPa might be affecting transport for species such as N2O Bry low

  47. CMAM Bry differs because Wamsley Reln considers CH2Br2, which is known to reach the stratosphere HTOT slightly low

  48. CNRM-ACM Woodbridge and Wamsley Relns Scaled to Feb 1996 HTOT high: puzzling due to very cold tropopause

  49. GEOS CCM Bry slightly low, even considering neglect of CH2Br2

  50. MRI Cly slightly high Bry very high

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