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

Evaluation of the Chemical Mechanismwithin CCMs using a constrained

Photochemical 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:

[email protected]

• 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

mailto:[email protected]

http://www.atmos.umd.edu/~rjs/ccmval/

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Evaluation of the Chemical Mechanismwithin CCMs using a constrained

Photochemical 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”

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Chemical Mechanism

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

Long-lived radical precursors:

O3, H2O, CH4, CO, NOy, Cly, Bry

Once we know: O(3P), O(1D), OH, HO2,


Compute:

dO3/dt terms, etc

4

Chemical Mechanism

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

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Chemical Mechanism

Chemical Mechanism









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 PL =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

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Chemical Mechanism

Chemical Mechanism









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

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PSS Model Comparisons: T3I files (shown in Toronto)

Model Comment

CAM 3.5 Highest model level is 3.55 hPa†

CCSR NIES All files present

CMAM Missing sad_sulf*; ClO on different eta grid

CNRM-ACM All files present

GEOS CCM Missing sad_sulf*

MRI Missing sad_sulf*

UMSLIMCAT Missing sad_sulf*, O1D, & O3P

BrO missing; Brx saved as Bry

WACCM Years 1990 to 1994 not posted on BADC; files for these years obtained privately from Doug Kinnison

† 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 prescribedcolors we were asked to use.

8

PSS Model Comparisons: T3I files (post Toronto)

Model Comment

UMUKCA-METO

Missing sad_sulf* & O1D

Mass mixing ratio written rather than volume mixing ratio

AMTRAC All files present for PSS comp days only

EMAC Missing sad_sulf*

Output written in hybrid coordinate system

SOCOL Missing sad_sulf*, O1D, & O3P

ULAQ All files present

LMDZrepro Missing O1D & O3P

Niwa_SOCOL Not enough files available to conduct comparisons

E39CA No T3I files yet posted

UMUKCA-UCAM

No T3I files yet posted

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 35N, Sept 1993:a) time of high aerosol loadingb) 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 22N, Feb 1996:a) measurement of HOx, NOx, ClO & precursors in the tropical UT/LS regionb) 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

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

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

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

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

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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

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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

Aerosol Surface Area Profiles• AMTRAC sulfate surface area only provided for two days• Profiles differ somewhat from prescribed climatology

NCCM CLIMATOLOGY

0 Sulf_sad

abs(Sulf_sad Sulf_sad )1g = 1

N 3

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)

19

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

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




Analysis restricted to modelvalues between tropopause(which we determine foreach model) and 30 km

20

Aerosol Surface Area Profiles• CCSR NIES sulfate surface area looks very reasonable

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




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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

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




22

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

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




23

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

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




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Aerosol Surface Area Profiles• ULAQ sulfate surface area is quite larger than prescribed climatology in Sept 1993, leading to a very low g value

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




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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

NCCM CLIMATOLOGY

0 Sulf_sad


N 3




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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

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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

Error BarsData: 1 std dev, total meas uncertaintyModel: 1 std dev, about zonal mean

Upper Strat Cly Sept 1993 Upper Strat Bry Sept 1993

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CAM 3.5

Bry low

Model lid at 3.5 hPa might be affectingtransport for species such as N2O



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CMAM



31

CNRM-ACM

Bry present in troposphereCly present in troposphere

ColdTropopause



32

GEOS CCM

LowTropopause



Cly low Bry low

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MRI

Bry high

Bry present in troposphere

LowTropopause



34

UMSLIMCAT

LowTropopause

Model Output Not AvailableFor p > 170 hPa



Bry high: a VSL bromocarbon

source of ~6 ppt was used in this run

35

CCSR NIES



Bry very high

Cly

high

Lots of Bry present in trop

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UMUKCA-METO

Bry present in troposphereCly present in troposphere



37

AMTRAC



Cly a litte lowBry somewhat low

38

EMAC

LowTropopause



Bry low

39

SOCOL



Bry very high

Cly

high

Some Bry present in trop

40

ULAQ




Unusual O3

profile

41

LMDZrepro




Bry high: looks like a

VSL bromocarbon source may have been

used in this run

42

Second Set of Comparisons• Tracer vs tracer plots to follow for ~35N, Sept 1993 for 13 models



43

WACCM

Woodbridge and Wamsley RelnsScaled to Sept 1993

44

WACCM

Bry differs because Wamsley Reln considers CH2Br2, which is known

to reach the stratosphere

45

CAM 3.5


Bry low


Woodbridge and Wamsley RelnsScaled to Sept 1993

46

CMAM

HTOT slightly low



47

CNRM-ACM

HTOT high: puzzling due tovery cold tropopause

Cly a bit high throughout stratosphere

48

GEOS CCM

Bry slightly low, even considering neglect of CH2Br2Cly slightly low

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MRI

Bry very highCly slightly high

50

UMSLIMCAT

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

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CCSR NIESScale Change

Bry very high(may actually becorrect, however )

Cly high

HTOT very low

Scale Change

O3 high

52

UMUKCA-METO

O3 vs N2Oa bit different

than data;all other relns

look fine

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AMTRAC

Cly a bit low Bry a bit low

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EMAC

Bry low, even considering neglect of CH2Br2

HTOT slightly low

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SOCOL

Cly high

Bry very high(may actually becorrect, however )

O3 vs N2O“shifted”

56

ULAQ

All other tracer relations look good

O3 vs N2O quitedifferent than data

(and most other models)

57

LMDZrepro

Bry high: looks like a VSL bromocarbon was used in this run

58

Third Set of Comparisons• Radical (CCMVal) and radial (PSS) profile plots for ~35N, Sept 1993 for 13 models



59

Third Set of Comparisons• As promised in Toronto, we have now computed “error bar” for PSS model values of O(3P), O(1D), HOx, NOx/NOy, ClO/Cly, and BrO/Bry by propagating the variance,

about the zonal monthly mean, of inputs to the PSS model (i.e., T, O3, H2O,

etc derived from each CCM model black error bars on following plots (PSS)

• We also computed the variance of the zonal mean of the CCM profiles of O(3P), O(1D), HOx, NOx/NOy, ClO/Cly, and BrO/Bry based on analysis of output for various

days in the month used to define the zonal mean colored error bars on following plots (CCM)

• When error bars overlap, or nearly overlap, as is often the case in the lowermost stratosphere, this means the way we sampled the CCM might be the cause of the difference between PSS and CCM values

60

Third Set of Comparisons• We then use PSS and CCM in the computation of g, which is shown for each panel

of each plot (this took a fair amount of effort to setup and formulate ):

NCCM PSS

0 CCM PSS

abs(Mixing Ratio Mixing Ratio )1g = 1

N 3 ( )

where we have: a) floored g at 0 for each altitude (i.e., g is not allowed to go negative) b) PSS floored at 5% of baseline value from PSS model at all altitudes (i.e, in the calculation of g, we

assume the PSS model is in error by at least 5% at all levels … this is not represented in our plots, but is represented in the computation of g and the log files we have posted

c) evaluated g between: the tropopause (which we determine) and 1 hPa for all species except BrO/Br y, the tropopause (which we determine) and 5 hPa for all BrO/Bry (there seem to be

issues with model representation of BrO at high altitude, where it simply does not matter, for BrO we focus on only the altitudes that matter

d) evaluated g for JPL 2002 kinetics and JPL 2006 kinetics for O(1D) and BrO/Bry, and propagate the higher value of g (many CCMs clearly did not add the O+BrONO2 reaction, new for JPL 2006, into their chemical mechanism; since we can account for this nuance, we will show the best value of g, but will indicate on the metric summary which kinetic set was used)

(again, this builds on the work of Waugh & Eyring, ACP, 2008)

61

WACCM

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

Values of g are not unity, however, because the multi-decadal log plots obscure small differences

There is ared line

under theblack

There is ared line

under theblack

There is ared line

under theblack

TropopausePSS run only

above this level

62

CAM 3.5

SuspectBrONO2+O rxn,new for JPL-06,

has not beenadded NOx a little low

compared to PSS

Diff in ClO consistentwith diff in NOx

Looks good. NOx a little low. Would like to determine whether BrONO2+O rxn is included in model

Diff in BrO consistent

with diff in NOx

For this model, neglectedhighest altitude pointin computation of g

due to uncertainties inoverhead conditions

63

CMAM

Have confirmedBrONO2+O rxn,new for JPL-06,

has not beenincluded !

Looks great! Sulfate SA file from CMAM is not yet submitted but no reason to suspect any difficulty.

64

CNRM-ACM

NOx suppressed,perhaps due to cold T.Not picked up by PSS

ClOx slightly activatedperhaps due to PSC like T

Looks likeBrONO2+Onot used

Looks good; differences in lowermost stratosphere likely due to response in CNRM-ACM to very cold T.Would like to determine whether BrONO2+O rxn is included in model.

65

GEOS CCM

ClO slightlyhigh

Looks good. However, the chemical mechanism in this model seems to over-estimate ClO in theupper stratosphere.


BrO not imp.at high alt

Very lowtropopause

in this model

66

MRI

HOx low

NOx high

ClO high

The chemical mechanism used in this model seems to differ from PSS in numerous important manners.Would like to run with MRI sulfate surface area! However, this will not affect comparisons at high altitude.

Scale Change

67

UMSLIMCAT

O(3P) filenot submitted

O(1D) filenot submitted

BrO file not submitted;have to compare BrO+Br

NOx slightly lower than PSS,perhaps due to surface area

mismatch ClO offset consistent with NOx

HOx offset consistentwith NOx

Looks like BrONO2+Ohas been included

Looks good. Would like to examine O(3P), O(1D), BrO,and run with UMSLIMCAT sulfate surface area.

Scale Change

Difference inconseq.;

BrO does notmatter

at high altitude

68

CCSR NIES


NOx highClO activation due to

very cold T, picked up by PSS !

HOx consistentwith NOx

Looks reasonable except for O1D. NOx is higher than PSS for most altitudes. Differences inHOx consistent with NOx. Looks like BrONO2+O not included.

Scale Change

69

UMUKCA-METO

NOx very high ClOx quite low,consistent with high NOx


The chemical mechanism used in this model seems to differ from PSS in important manners throughout the lower stratosphere. Would like to run with UMUKCA-METO sulfate surface area,

which could affect interpretation in regions of large discrepancy.

HOx very low,consistent with

forcing from NOx

70

AMTRAC


Looks great except for some differences in ClO in the upper stratosphereand the likely neglect of BrONO2+O.

71

EMAC


Looks great. Suspect BrONO2+O has not been considered in EMAC. Also, appearsO(1D) is found using JPL 2002 kinetics.

72

SOCOL

The chemical mechanism used in this model seems to differ from PSS in a somewhat important manner throughoutthe lower stratosphere. Would like to run with SOCOL sulfate surface area, which could affect interpretation

of results in region of large discrepancy, and also compare to O(3P) and O(1D).

NOx lowClO high, some activation

at tropopuse

HOx spot on.Somewhat surprising

given mismatchfor NOx

BrO sig lowerthan PSS



73

ULAQ

The chemical mechanism used in this model seems to differ from PSS in a somewhat important mannerthroughout the stratosphere. Differences in ClOx mirror those of NOx

(similar magnitude, opposite sign), which is reassuring.

NOx low

ClO quite low in upper strat

HOx close.A bit surprising

given mismatchesfor O(1D) & NOx

BrO sig lowerthan PSS

O(1D) low

NOx high

ClOx high

Scale Change

74

LMDZrepro

Looks likeBrONO2+O

was used !!!

Chemical mechanism looks just like the PSS simulation. Impressive .Would like to see O(3P) and O(1D) for completeness.



75

The Metric Plot• This plot show, in a single image, the values of g from all of the prior plots• So, can ignore previous 74 slides and focus just on this one

We’ve decided to use the same colorfor 0.8 to 0.9 as used for 0.9 to 1.0,because we feel g > 0.8 is an excellentevaluation and there is little scientificmeaning in splitting hairs once thisthreshold has been reached

Please see g*log files posted atwww.atmos.umd.edu/~rjs/ccmval/g_valuesfor a record of how the values of gshown in this metric plot were tabulated.

http://www.atmos.umd.edu/~rjs/ccmval/g_values

76

New Comparison Plots• Following series of plots show profiles of sulfate SA, HNO3, N2O5, Lifetime of NOx •and HCl (for diagnostic purposes from PSS), ClNO3, and HCl

• Error bars are variability of the zonal mean from CCM model; error bars are large for N2O5 because this species varies diurnally. Nonetheless, the 24 hr avg value of N2O5 from PSS goes right through the middle of the zonal monthly mean value for many of the CCM models, as it is generally expected to do if we are correctly implementing the same chemical mechanism

• These plots provided additional insight and “support” for inconsistencies seen in prior plots for a few models

• Have resisted extensive written comments on the plots that follow

77

WACCM

78

CMAM

79

CNRM-ACM

80

GEOS CCM

81

MRI

Significant Differences

82

UMSLIMCAT

83

CCSR NIES

84

UMUKCA-METO

Signif differences

85

AMTRAC

Sulfate SA profileslook quite different(see earlier slides

comparing to inputclimatology)

Diffs consistentwith those for

ClO

86

EMAC

87

SOCOL

Diffs consistentwith those for

ClO & NOx

88

ULAQ

Yikes! Not sure whatis happening here(see earlier slides

comparing to inputclimatology)

Significant Differences

89

LMDZrepro

Yikes!!! Not sure what isgoing on here. But, as shown

in the SA time series plots,sulf_sad from this model quite

different than prescribedclimatology

All other comparisons exceptionally good

90

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 groupswho are interested in diagnosing the reasons for differences betweenradical fields computed by their CCM and the PSS model

We’ll develop “grades” based on these comparisons upon request

91

Comparisons for 22N, Feb 1996 to follow

Note: nothing that follows has yet been updated since the Toronto meeting Updates to be provided soon.

We intend to compute g_values for this comparison, whichis essential to search for consistency (or lack thereof)with results found for the 35N, Sept 1993 comparisons

92

WACCM

CCM Tropopause


Upper Strat Cly Feb 1996

93

CAM 3.5

CCM Tropopause




94

CMAM

CCM Tropopause



95

CNRM-ACM

CCM Tropopause



96

GEOS CCM

CCM Tropopause

LowTropopause



97

MRI

CCM Tropopause

LowTropopause



98

UMSLIMCAT

CCM Tropopause

LowTropopause

Model Output Not AvailableFor p > 170 hPa



99

WACCM

Woodbridge and Wamsley RelnsScaled to Feb 1996

100

WACCM



101

CAM 3.5


Bry low



102

CMAM

HTOT slightly low



103

CNRM-ACM

HTOT high: puzzling due tovery cold tropopause


104

GEOS CCM

Bry slightly low, even considering neglect of CH2Br2

105

MRI

Bry very highCly slightly high

106

UMSLIMCAT

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

107

WACCM

Some differences in LMS/UT. Unclear why O(1D) would differ.NOx differs by somewhat more than expected, which bears further investigation.

There is ared line

under theblack

There is ared line

under theblack

There is ared line

under theblack

108

CAM 3.5

SuspectBrONO2+O rxn,new for JPL-06,

has not beenadded

Diff in ClO consistentwith diff in NOx

Looks good. Would like to examine O(3P)and determine whether BrONO2+O rxn is included in model

Diff in BrO consistent

with diff in NOx

NOx lowcompared to PSS

109

CMAM

Have confirmedBrONO2+O rxn,new for JPL-06,

has not beenincluded !

Looks great! Would like to examine O(3P) and O(1D)and determine whether BrONO2+O rxn is included in model


110

CNRM-ACM

NOx in near zerodue to PSC like T

relevant chemistryClOx in PSS activated

due to PSC like TLooks likeBrONO2+O

rxn not added

Looks good; would like to determine whether “PSC chemistry” has been “turned off” for extra-polar regionsand whether BrONO2+O rxn is included in model.

Scale Change

111

GEOS CCM

ClO slightlyhigh

BrO slightlylow

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.

Looks likeBrONO2+O

rxn not added

BrO not imp.at high alt

Has ClO+OH HCl notbeen added ?!?

112

MRI



ClO high

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.

Scale Change


113

UMSLIMCAT



BrO file not submitted;have to compare BrO+Br

ClO offset consistent with NOx

HOx offset consistentwith NOx

Difference inconseq.;BrO does not matter

at high altitude

Looks great. Would like to examine O(3P), O(1D), BrO,and run with UMSLIMCAT sulfate surface area.

Scale Change


Documents

1 Evaluation of the Chemical Mechanism within CCMs using a constrained Photochemical Steady State (PSS) Model Ross Salawitch 1, Ben Johnson 1, Tim Canty