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Ross Salawitch 1 , Ben Johnson 1 , Tim Canty 1 ,

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

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Ross Salawitch 1 , Ben Johnson 1 , Tim Canty 1 ,

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  1. Evaluation of the Chemical Mechanismwithin CCMs using a constrainedPhotochemical Steady State (PSS) Model • Ross Salawitch1, Ben Johnson1, Tim Canty1, • 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 *REF-B1*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 9 September 2009 Update

  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 (shown in Toronto) † O3 and T from WACCM above 3.55 hPa used for J value computation * sad_sulf from WACCM used for analysis Sorry our color schemes are not yet consistent with the prescribed colors we were asked to use.

  8. PSS Model Comparisons: T3I files (post Toronto)

  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. Aerosol Surface Area • Many modeling groups did not provide sulfate aerosol surface area, which was • prescribed for this run • Value had been requested (variable sad_sulf) so that we could be sure to run the • If sad_sulf is missing, then profiles of sad_sulf vs pressure from WACCM are used • to interpolate onto the pressure grid of each model (the prescribed climatology are • time series at various altitudes; since altitude was not output (or given) by the various • modeling groups, use of this prescribed climatology is a challenge • For groups that did provide sad_sulf, we compare to the climatology by: • a) calculating geometric altitude by integrating the model pressure/temperature • (there is some ambiguity in this calculation, such as surface pressure, surface • topography, and whether or not g is allowed to vary with height) • b) compare to the climatological time series at 5 altitudes

  11. Aerosol Surface Area Time Series • CAM 3.5 sulfate surface area compares will with prescribed climatology

  12. Aerosol Surface Area Time Series • CCSR NIES sulfate surface area compares will with prescribed climatology

  13. Aerosol Surface Area Time Series • CNRM-ACM sulfate surface area compares will with prescribed climatology

  14. Aerosol Surface Area Time Series • ULAQ sulfate surface area appears to be quite different than prescribed climatology

  15. Aerosol Surface Area Time Series • WACCM sulfate surface area compares will with prescribed climatology

  16. Aerosol Surface Area Time Series • LMDZrepro sulfate surface area is also quite different than prescribed climatology

  17. Aerosol Surface Area • LMDZrepro sulfate surface area is also quite different than prescribed climatology • AMTRAC provided profiles of SA just for days of interest, and hence • we can not produce time series plots for this model • GEOS CCM ran using background aerosol as a function of latitude • and altitude; we could produce time series plots using this information, • but it does not seem

  18. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • AMTRAC sulfate surface area only provided for two days • Profiles differ somewhat from prescribed climatology

  19. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • CAM sulfate surface area agrees quite well with prescribed climatology • for the two times and places for which we will conduct PSS comparisons Analysis restricted to model values between tropopause (which we determine for each model) and 30 km

  20. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • CCSR NIES sulfate surface area looks very reasonable

  21. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • CNRM-ACM sulfate surface area higher than prescribed climatology in lower stratos • Strangely, same value of g found for both cases

  22. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • GEOS CCM was run using background surface area, resulting in low g for Sept 1993 • Important we use proper sulfate surface area profile for in the PSS comparisons

  23. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • LMDZrepro sulfate surface area profile is less than climatology in lower stratos • Unusual shape of sulfate surface area profile for Feb 1996 case

  24. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • ULAQ sulfate surface area is quite larger than prescribed climatology in Sept 1993, • leading to a very low g value

  25. where we have: a) integrated p vs T of each CCM model to arrive at an estimate of geometric altitude because the Sulf_sad climatology is given only as a function of altitude and latitude b) estimated Sulf_sad based on the sum of differences between adjacent 5 latitude bins of the climatology and the difference of Sulf_sad for a 0.2 km uncertainty in altitude (error bars represent Sulf_sad) c) floored g at 0 for each altitude (i.e., g is not allowed to go negative) (this follows Waugh & Eyring, ACP, 2008) Aerosol Surface Area Profiles • WACCM sulfate surface area profile shifted slightly wrt altitude compared to the • climatology, perhaps reflecting difficulty of using data on a geometric altitude grid

  26. Aerosol Surface Area Summary Differences in prescribed sulfate surface area and values of the variable sulf_sad in the *REF-B1*T3I* files submitted by AMTRAC, GEOSCCM, LMDZrepro, and ULAQ underscores the importance of other groups submitting, to the archive, values of sulf_sad for the PSS comparison. At the present time, we lack sulf_sad from the following groups: CMAM, EMAC, GEOS CCM, MRI, SOCOL, UMUKCA-METO, and UMSLIMCAT In the absence of sulf_sad submitted by various groups, we are assuming the climatology applies, but this may be an erroneous assumption, as is the case for AMTRAC, GEOSCCM, LMDZrepro, and ULAQ  Submission of files for sulf_sad also allows us to test whether we are properly interpreting date in the submitted files: there are “issues” here due to some model’s use of a 360 day year, whether or not leap years are included, etc

  27. First Set of Comparisons • Tracer profile plots to follow for ~35N, Sept 1993 for 13 models • Results presented in same order as at Toronto meeting (first 8 models) and • in the order that calculations were conducted based on receipt of files (last 6 models) • Sorry that colors do not yet match requested scheme 

  28. 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

  29. 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

  30. 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

  31. 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 Cold Tropopause Cly present in troposphere Bry present in troposphere

  32. 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 Cly low Bry low

  33. 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 Bry high Bry present in troposphere

  34. 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 Model Output Not Available For p > 170 hPa Bry high: a VSL bromocarbon source of ~6 ppt was used in this run

  35. CCSR NIES Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Cly high Bry very high Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean Lots of Bry present in trop

  36. UMUKCA-METO 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 Cly present in troposphere Bry present in troposphere

  37. AMTRAC 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 Bry somewhat low Cly a litte low

  38. EMAC 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 Bry low

  39. SOCOL Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993 Cly high Bry very high Error Bars Data: 1 std dev, total meas uncertainty Model: 1 std dev, about zonal mean Some Bry present in trop

  40. ULAQ 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 Unusual O3 profile  Bry present in troposphere

  41. LMDZrepro 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 Bry high: looks like a VSL bromocarbon source may have been used in this run Bry present in troposphere

  42. Second Set of Comparisons • Tracer vs tracer plots to follow for ~35N, Sept 1993 for 13 models • Results presented in same order as at Toronto meeting (first 8 models) and • in the order that calculations were conducted based on receipt of files (last 6 models) • Sorry that colors do not yet match requested scheme 

  43. WACCM Woodbridge and Wamsley Relns Scaled to Sept 1993

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

  45. 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

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

  47. CNRM-ACM HTOT high: puzzling due to very cold tropopause Cly a bit high throughout stratosphere

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

  49. MRI Cly slightly high Bry very high

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

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