PC-BLAG ITERATIVE PROGRAM RUNNING KUMP AND GARRELS 1986 BOX MODEL nerded by Pat Wilde Technische Universitat - Berlin Winter 1989-1990 Excel Version 12/97 Program requirements IBM Dos PC or clone 286 or greater Excel Spreadsheet (this was from Microsoft Office) Model Source: Kump, L. and Garrels, R. L., 1986, American Journal of Science, v. 286, p. 349 This program was originally on a Lotus 123@ spreadsheet takes advantages of the iterative ability of Version 3+ to display the workings of the Kump and Garrels (K&G 1986) version of the BLAG (Berner, Lasaga, and Garrels) whole earth model. This Excel version is a translation of the original program. It is not as fancy as the 123 version (color codes etc.), but should still work. PROGRAM ARRANGEMENT Cells A6 to F29 are the viewing fields during the iterations. Column A gives the parameter (i.e PYR:S = Pyrite sulfur. Column B gives the initial reservoir value. Column C gives the working reservoir value which is a function of the iteration. Column D gives the increment or decrement value used to calculate the next working value. Column E gives the variation from the initial value. Column F gives the % variation from the initial value. Cells A30 to F55 are the operational fields using the rates from K&G 1986 or rates substituted by the user. Column A is the box model identifier such as OX for Oxygen, PHOTO for photosynthesis etc. Column B gives the rate designator from K&G 1986. Column C gives the working rate. Column D gives the rate from K&G 1986. Column E gives the working factor (1 if the K&G rate is uses). Column F gives the rate set by the user as a decimal of the K&G 1986 rate (for example: 95 % of K&G 1986 rate would be .95, 101 % would be 1.01. Cells F68 to Z170 are the set-up tables for Graphics for 100 iterations for each of the reservoirs. Plots of changes with steps can be made using 123 graphic option with choice of plots and parameters up to the user. Isotope values generally go bananas during early iterations so some scale changes are required. Cells A56..B11 and E61..F63 are the Macro definitions. THESE CELLS SHOULD NOT BE CHANGED*****REPEAT*****THESE CELLS SHOULD NOT BE CHANGED as they control the operations of the program. If you wish to change the iterations MAKE SURE YOU HAVE A BACK-UP COPY OF THE ORIGINAL MACROS. HOW TO OPERATE I. CELLS THAT CAN BE CHANGED ITERATION STEPS C1: value in cell gives the initial start number. This is usually set to 1 to start the iterations from the initial values in the K&G model. It can be set to any value up the value of cell C2. C2: value in cell gives the total number of iterations you wish to run. The program runs very fast with a math co- processor. However without a co-processor it takes about a second per iteration. In general the program converges between 30 to 40 iterations. C3: value in cell gives the number of steps the program proceeds towards the value in C2. For example if C2 is 100, C1 is 1 and C3 is 2, the program steps and the screen displays or steps every 2 iterations. RATE MODIFICATIONS of K&G 1986 values F33..F55 value in cell gives the decimal fraction of the K&G 1986 rate selected by user. OPERATIONAL KEYS FOR ITERATIONS Starts iterations with settings in C1, C2, C3 and working rate values in E33..E55. Resets working values to K&G 1986 original rate values. Places user selected values from F33..F55 into working column. EXAMPLE: (This is done in column F in FTP zipped file) Consider potential Human influence on Model 1. Modify photosynthesis by cutting down rain forests etc. * Estimated effect of reduction of 1%. Change values in cells F35 and F36 to .99. 2. Increase agriculture and urbanization and thus increasing erosion. * Estimated effect of increase of 1%. Change values cells F46 to F55 to 1.01. PROCEDURE 1. Press to return spreadsheet to initial condition. 2. Press to place new user rate values from column F in working columns. **Should be typed in before hitting ** 3. Set iteration values in C1..C3 4. Set upper left corner of screen to A8, so you may observe changes as the program iterates. 5. Press to run iterations. Number of cycles appears on upper right corner of screen during iterations. Values in appropriate cells changes with each iteration. 6. At end of run, Graphics can be made from Table of values at F58..Z170 for iterations up to 100. This Table is recalculated automatically every time is pressed. ********** I hope this is sufficiently clear. Any user of Excel or 123 should not have much difficulty in operating the program or plotting the graphics. The iterative procedures are less obvious, so modifications to the Macros should be made with caution and with the 123 manual handy. As this is a translation of an a 123 spreadsheet, one must be cautious in modifying the Macro in Excel. ***********