date: 15 Dec 1997 14:14:53 -0700
from: Tom Wigley <Tom_Wigley@qgate.ucar.edu>
subject:  MAGICC CH4 results
to: Mike Hulme <m.hulme@uea.ac.uk>, Sarah Raper <s.raper@uea.ac.uk>


Dear Mike and Sarah,

I have revised some of the code in MAGICC to improve the CH4 results.
There were two glitches.  The first was in the initialization of ECH4 to
give a balanced 1990 budget.  By a fluke, this didn't affect any results
because of the specific choice of parameters I had.  The second was in the
calculated CH4 concentrations.  I had tuned the model to match an early
set of IPCC results, and these are all somewhat lower than the published
values.  This required tedious trial and error retuning of the methane
model parameters, which I have now done.  The new parameters are better,
because a single set works for all IS92 scenarios---previously different
parameters were required for A,B,E,F versus C,D.

With regard to the distributed code, we have to make a choice whether to
stick to the old code (which agrees with Ch. 6, but not Ch. 2) or the new
code (which agrees with Ch.2).  I'm inclined to go with Ch. 2 consistency
and the new code.  What do you think?

I have more things to clean up in MAGICC, so I won't send the new code
(for MAG.FOR) until I've done these. In the meantime, here are the header
notes from the new code to fill in some details.

Cheers,

Tom
C MAG.FOR

C

C Revision history:

C

C 971214  * METHANE PARAMS CHANGED TO GIVE BETTER SIMULATIONS OF IPCC

C            SAR RESULTS AS PER TABLE 2.5a IN SAR. 1990 TAU SET TO 9.1:

C            PREVIOUSLY 9.08. IF DELTAU IS SET AT +/- 0.8 (CF. IPCC

C            RANGE IS +/- 1.8), WHICH MAKES HIGH TAU = 9.9, AND 

C            ITAUMETH IS SET AT 3 (WHICH GIVES UPPER BOUND CONCS FOR 

C            THE ORIGINAL OSBORN & WIGLEY MODEL) THEN OUTPUT AGREES 

C            EXTREMELY WELL PRATHER'S IPCC RESULTS. THIS IMPLIES THAT 

C            PRATHER'S MODEL MUST HAVE A HIGH TAU AND/OR A TAU 

C            SENSITIVITY THAT DIFFERS SUBSTANTIALLY FROM THE CENTRAL 

C            OSBORN & WIGLEY VALUE.

C

C            COMPARISON OF PRATHER IPCC (CH.2) AND CURRENT MODEL (IPCC

C            VALUES HAVE 17ppbv ADDED BECAUSE THE IPCC VALUE IN 1990

C            IS 17ppbv BELOW THE VALUE USED HERE - THIS MAKES THE

C            COMPARISON HERE MORE TRUE TO A FORCING COMPARISON).

C

C            RESULTS BELOW ARE IN ORDER : OLD VERSION (I.E., NUMBER 

C            USED IN CH.6 OF SAR); NEW VERSION; IPCC (CH.2). NOTE THAT

C            THE MAIN REASON WHY THE CH.6 VALUES ARE SO DIFFERENT FROM

C            THE IPCC CH.2 VALUES IS THAT THE PRESENT MODEL WAS TUNED

C            TO AN EARLY VERSION OF PRATHER'S RESULTS.

C

C            SCENARIO         2050 CONCS           2100 CONCS

C            IS92A,B       2764  2833  2810     3467  3611  3633

C            IS92C         2148  2252  2241     1997  2088  2086

C            IS92D         2157  2259  2247     2056  2161  2163

C            IS92E         2972  3056  3031     4109  4301  4308

C            IS92F         2996  3081  3055     4492  4711  4686

C                          CH.6   NEW  CH.2     CH.6   NEW  CH.2

C

C

C            THE TABLE BELOW COMPARES NEW WITH OLD (IPCC CH.6) T & MSL

C             CHANGES OVER 1990-2100.

C

C            SCENARIO  SIMULATION    OLD DT     NEW DT  OLD DMSL  NEW DMSL

C            IS92C     LOW           0.8622     0.8747     12.63     12.86

C            IS92A     MID           2.0308     3.0504     48.94     49.28

C            IS92E     HIGH          3.5260     3.5601     94.75     95.21

C

C 971213  * ERROR IN CORRECTING INPUT METHANE EMISSIONS FOR 1990

C            IMBALANCE CORRECTED (SUBSTANTIAL REVISION). THIS WAS FIRST

C            CORRECTED IN OPT.FOR ON 961024. IT MAKES NO DIFFERENCE

C            TO THE OUTPUT: OUTPUT IS ONLY AFFECTED FOR NON-ZERO DELTAU.

C            IN PREVIOUS VERSION OF THE CODE, DELTAU WAS SET TO ZERO.

C 971123  * TWO ERRORS FOUND

C            (1) S90IND=0.0 INPUT CAUSES CRASH. CORRECTED TEMPORARILY

C                 BY RESETTING S90IND=-0.0001

C            (2) EQUIVCO2 MISCALCULATED (USED IF NOUT=4 ONLY).

C                 CODE CORRECTED.

 TABLE 1: FOSSIL CO2 EMISSIONS DATA USED IN CARBON CYCLE CALCULATIONS.



                 MODIFIED IS92a                  KYOTO         EXTENDED KYOTO

 YEAR  ANNEX I   NON-I   BUNKER   GLOBAL    ANNEX I  GLOBAL    ANNEX I  GLOBAL

 1990    3.907   2.088    0.114    6.109      3.907   6.109      3.907   6.109

 1991    3.791   2.270    0.117    6.178      3.791   6.178      3.791   6.178

 1992    3.708   2.240    0.136    6.084      3.708   6.084      3.708   6.084

 1993    3.631   2.293    0.129    6.053      3.631   6.053      3.631   6.053

 1994    3.676   2.484    0.132    6.292      3.676   6.292      3.676   6.292

 1995    3.801   2.567    0.138    6.506      3.801   6.506      3.801   6.506

 1996    3.869   2.662    0.138    6.669      3.869   6.669      3.869   6.669

 1997    3.920   2.758    0.138    6.816      3.920   6.816      3.920   6.816

 1998    3.971   2.854    0.138    6.963      3.971   6.963      3.971   6.963

 1999    4.022   2.950    0.138    7.110      4.022   7.110      4.022   7.110

 2000    4.073   3.046    0.138    7.257      4.073   7.257      4.073   7.257

 2001    4.110   3.177    0.138    7.425      4.029   7.344      4.029   7.344

 2002    4.147   3.308    0.138    7.593      3.985   7.431      3.985   7.431

 2003    4.183   3.440    0.138    7.761      3.941   7.519      3.941   7.519

 2004    4.220   3.571    0.138    7.929      3.897   7.606      3.897   7.606

 2005    4.257   3.702    0.138    8.097      3.853   7.693      3.853   7.693

 2006    4.294   3.814    0.138    8.246      3.810   7.762      3.810   7.762

 2007    4.331   3.924    0.138    8.393      3.766   7.828      3.766   7.828

 2008    4.367   4.036    0.138    8.541      3.722   7.896      3.722   7.896

 2009    4.404   4.146    0.138    8.688      3.678   7.962      3.678   7.962

 2010    4.441   4.258    0.138    8.837      3.634   8.030      3.634   8.030

 2011    4.478   4.370    0.138    8.986      3.634   8.142      3.598   8.106

 2012    4.515   4.480    0.138    9.133      3.634   8.252      3.562   8.180

 2013    4.551   4.592    0.138    9.281      3.634   8.364      3.526   8.256

 2014    4.588   4.702    0.138    9.428      3.634   8.474      3.491   8.331

 2015    4.625   4.814    0.138    9.577      3.634   8.586      3.456   8.408

 2016    4.662   4.945    0.138    9.745      3.634   8.717      3.421   8.504

 2017    4.699   5.077    0.138    9.914      3.634   8.849      3.387   8.602

 2018    4.735   5.207    0.138   10.080      3.634   8.979      3.353   8.698

 2019    4.772   5.339    0.138   10.249      3.634   9.111      3.320   8.797

 2020    4.809   5.470    0.138   10.417      3.634   9.242      3.287   8.895

 2021    4.846   5.601    0.138   10.585      3.634   9.373      3.254   8.993

 2022    4.883   5.733    0.138   10.754      3.634   9.505      3.221   9.092

 2023    4.919   5.863    0.138   10.920      3.634   9.635      3.189   9.190

 2024    4.956   5.995    0.138   11.089      3.634   9.767      3.157   9.290

 2025    4.993   6.126    0.138   11.257      3.634   9.898      3.125   9.389

 2026    4.993   6.230    0.138   11.361      3.634  10.002      3.094   9.462

 2027    4.993   6.334    0.138   11.465      3.634  10.106      3.063   9.535

 2028    4.993   6.438    0.138   11.569      3.634  10.210      3.033   9.609

 2029    4.993   6.542    0.138   11.673      3.634  10.314      3.002   9.682

 2030    4.993   6.646    0.138   11.777      3.634  10.418      2.972   9.756

 2031    4.993   6.750    0.138   11.881      3.634  10.522      2.943   9.831

 2032    4.993   6.854    0.138   11.985      3.634  10.626      2.913   9.905

 2033    4.993   6.958    0.138   12.089      3.634  10.730      2.884   9.980

 2034    4.993   7.062    0.138   12.193      3.634  10.834      2.855  10.055

 2035    4.993   7.166    0.138   12.297      3.634  10.938      2.827  10.131

 2036    4.993   7.270    0.138   12.401      3.634  11.042      2.798  10.206

 2037    4.993   7.374    0.138   12.505      3.634  11.146      2.770  10.282

 2038    4.993   7.478    0.138   12.609      3.634  11.250      2.743  10.359

 2039    4.993   7.582    0.138   12.713      3.634  11.354      2.715  10.435

 2040    4.993   7.686    0.138   12.817      3.634  11.458      2.688  10.512

 2041    4.993   7.790    0.138   12.921      3.634  11.562      2.661  10.589

 2042    4.993   7.894    0.138   13.025      3.634  11.666      2.635  10.667

 2043    4.993   7.998    0.138   13.129      3.634  11.770      2.608  10.744

 2044    4.993   8.102    0.138   13.233      3.634  11.874      2.582  10.822

 2045    4.993   8.206    0.138   13.337      3.634  11.978      2.556  10.900

 2046    4.993   8.310    0.138   13.441      3.634  12.082      2.531  10.979

 2047    4.993   8.414    0.138   13.545      3.634  12.186      2.505  11.057

 2048    4.993   8.518    0.138   13.649      3.634  12.290      2.480  11.136

 2049    4.993   8.622    0.138   13.753      3.634  12.394      2.456  11.216

 2050    4.993   8.726    0.138   13.857      3.634  12.498      2.431  11.295

 2051    5.011   8.806    0.138   13.955      3.634  12.578      2.407  11.351

 2052    5.028   8.886    0.138   14.052      3.634  12.658      2.383  11.407

 2053    5.046   8.968    0.138   14.152      3.634  12.740      2.359  11.465

 2054    5.063   9.048    0.138   14.249      3.634  12.820      2.335  11.521

 2055    5.081   9.128    0.138   14.347      3.634  12.900      2.312  11.578

 2056    5.099   9.208    0.138   14.445      3.634  12.980      2.289  11.635

 2057    5.116   9.289    0.138   14.543      3.634  13.061      2.266  11.693

 2058    5.134   9.369    0.138   14.641      3.634  13.141      2.243  11.750

 2059    5.151   9.450    0.138   14.739      3.634  13.222      2.221  11.809

 2060    5.169   9.530    0.138   14.837      3.634  13.302      2.199  11.867

 2061    5.187   9.610    0.138   14.935      3.634  13.382      2.177  11.925

 2062    5.204   9.691    0.138   15.033      3.634  13.463      2.155  11.984

 2063    5.222   9.771    0.138   15.131      3.634  13.543      2.133  12.042

 2064    5.239   9.852    0.138   15.229      3.634  13.624      2.112  12.102

 2065    5.257   9.932    0.138   15.327      3.634  13.704      2.091  12.161

 2066    5.275  10.012    0.138   15.425      3.634  13.784      2.070  12.220

 2067    5.292  10.093    0.138   15.523      3.634  13.865      2.049  12.280

 2068    5.310  10.173    0.138   15.621      3.634  13.945      2.029  12.340

 2069    5.327  10.254    0.138   15.719      3.634  14.026      2.008  12.400

 2070    5.345  10.334    0.138   15.817      3.634  14.106      1.988  12.460

 2071    5.363  10.415    0.138   15.916      3.634  14.187      1.968  12.521

 2072    5.380  10.495    0.138   16.013      3.634  14.267      1.949  12.582

 2073    5.398  10.575    0.138   16.111      3.634  14.347      1.929  12.642

 2074    5.415  10.655    0.138   16.208      3.634  14.427      1.910  12.703

 2075    5.433  10.736    0.138   16.307      3.634  14.508      1.891  12.765

 2076    5.451  10.888    0.138   16.477      3.634  14.660      1.872  12.898

 2077    5.468  11.040    0.138   16.646      3.634  14.812      1.853  13.031

 2078    5.486  11.194    0.138   16.818      3.634  14.966      1.835  13.167

 2079    5.503  11.346    0.138   16.987      3.634  15.118      1.816  13.300

 2080    5.521  11.498    0.138   17.157      3.634  15.270      1.798  13.434

 2081    5.539  11.650    0.138   17.327      3.634  15.422      1.780  13.568

 2082    5.556  11.803    0.138   17.497      3.634  15.575      1.762  13.703

 2083    5.574  11.955    0.138   17.667      3.634  15.727      1.745  13.838

 2084    5.591  12.108    0.138   17.837      3.634  15.880      1.727  13.973

 2085    5.609  12.260    0.138   18.007      3.634  16.032      1.710  14.108

 2086    5.627  12.412    0.138   18.177      3.634  16.184      1.693  14.243

 2087    5.644  12.565    0.138   18.347      3.634  16.337      1.676  14.379

 2088    5.662  12.717    0.138   18.517      3.634  16.489      1.659  14.514

 2089    5.679  12.870    0.138   18.687      3.634  16.642      1.643  14.651

 2090    5.697  13.022    0.138   18.857      3.634  16.794      1.626  14.786

 2091    5.715  13.174    0.138   19.027      3.634  16.946      1.610  14.922

 2092    5.732  13.327    0.138   19.197      3.634  17.099      1.594  15.059

 2093    5.750  13.479    0.138   19.367      3.634  17.251      1.578  15.195

 2094    5.767  13.632    0.138   19.537      3.634  17.404      1.562  15.332

 2095    5.785  13.784    0.138   19.707      3.634  17.556      1.547  15.469

 2096    5.803  13.937    0.138   19.878      3.634  17.709      1.531  15.606

 2097    5.820  14.089    0.138   20.047      3.634  17.861      1.516  15.743

 2098    5.838  14.241    0.138   20.217      3.634  18.013      1.501  15.880

 2099    5.855  14.393    0.138   20.386      3.634  18.165      1.486  16.017

 2100    5.873  14.546    0.138   20.557      3.634  18.318      1.471  16.155

