ITVCM allows the following functionality:
Figure 2. Implementation diagram.
The black boxes represent the following items:
The red boxes represent input serial data provided by the user:
Figure 3. 203 gases implementation diagram
There are 203 gases described on gaspar.xls with structure more simplified than CO2, CH4 and N2O gases. For these gases, CONC and RF modules are unified, as we see on figure 3.
The diagrams on figures 2 and 3 show the calculation flow in a specific period. Equation coefficients are calculated together with their state variables, which are resolved with Runge-Kutta method. Other methods which were implemented for ordinary differential equations (ODEs) were Euler method and Runge-Kutta fourth-order method (RK4). The iterationType parameter has 'euler' and 'RK4' options to choose. The order of the iterative Runge-Kutta method indicates the error order (according to its expansion in Taylor's series) and how many evaluations about the function will be done in each step.
Figure 4 represents the difference between the temperatures seen on Euler and RK4 methods. The temperature differences between the years 1750 and 2100 is bigger than 3oC. The values difference between the same methods is always smaller than 0.01oC, which indicates a difference smaller than 0.33% between the methods.
Figure 4. Difference between the temperatures calculated on Euler and RK4 methods.