| Symbol | Description | Uses |
| i | loop indices | 44353 |
| IGNORE_TIME | 1 | |
| INCLUDE_CALC_DIFFUSIVITY_CALL | 3 | |
| INCLUDE_CONVECT_CALL | 4 | |
| INCLUDE_EOS_CHECK | 1 | |
| INCLUDE_EP_FORCING_CODE | 2 | |
| INCLUDE_IMPLVERTADV_CODE | 4 | |
| INCLUDE_PHIHYD_CALCULATION_CODE | 5 | |
| INCLUDE_WHIO_GLOBUFF_3D | 8 | |
| INCONSISTENT_WIND_LOCATION | 4 | |
| INTEL_COMMITQQ | 2 | |
| IPCC_EMI | 3 | |
| IS_DOUBLE | 2 | |
| ISOTROPIC_COS_SCALING | 35 |