| Abbreviation | Definition |
|---|---|
| ISABP | International South Atlantic Buoy Program |
| ISAG | IGOSS Scientific Advisory Group |
| ISAT | Initial Surface Absorption Test |
| ISBA | International Sea-Bed Authority |
| ISBC | International Society for Bioluminescence and Chemiluminescence |
| ISCCP | International Satellite Cloud Climatology Project |
| ISEE | International Sun Earth Explorer |
| ISHTAR | Inner Shelf Transfer And Recycling |
| ISIS | Integrated Surface Irradiance Study |
| ISLP | IGOSS Sea Level Project |
| ISLP-PAC | IGOSS Sea Level Project in the Pacific |
| ISLSCP | International Satellite Land Surface Climatology Project |
| ISO | International Organization for Standardisation |
| ISO | Intraseasonal Atmospheric Oscillation |
| ISOS | Integrated Surface Observing System |
| ISOS | International Southern Ocean Studies |
| ISPAN | Information Stream Project for AWIPS and NOAAport |
| ISPM | Interplanetary Shock Propagation Model |
| ISS | Inclination Sensor System |
| ISS | Integrated Sounding System |