| Abbreviation | Definition |
|---|---|
| AOML | Atlantic Oceanographic and Meteorological Laboratory |
| AOO | American Oceanic Organization |
| AORF | Arctic Ocean Radiative Fluxes |
| AOSB | Arctic Ocean Science Board |
| AOSP | Atmospheric and Ocean Sciences Program |
| AOSS | Atmospheric Oceanic and Space Sciences |
| AOU | Apparent Oxygen Utilization |
| AP | Arakawa Peil |
| APA | Alkaline Phosphatase Activity |
| APARD | Arctic Paleo-River Discharge |
| APARE | East Asian-North Pacific Regional Experiment |
| APD | Average Penetration Depth |
| APEX | Arctic Polynya Experiment |
| APIS | Antarctica Pack Ice Seals |
| APL | Applied Physics Laboratory |
| APMS | Automated Penguin Monitoring System |
| APO | AWIPS Program Office |
| AQTX | AQuatic ToXicity |
| ARAT | Atmospheric Research and Remote Sensing Plane |
| ARC | Automated Radiotheodolite |