| Abbreviation | Definition |
|---|---|
| AD | Aviation Division |
| ADAS | Airborne Data Acquisition System |
| ADCP | Acoustic Doppler Current Profiler |
| ADEOS | Advanced Earth Observing Satellite |
| ADF | Administrator's Discretionary Fund |
| ADF | Advanced Development Facility |
| ADFS | Automatic Debris Filter System |
| ADIOS | Asian Dust Input to the Oceanic System |
| ADIOS | Automated Data Inquiry for Oil Spills |
| ADL | Aerially Deposited Lead |
| AEC | Atomic Energy Commission |
| AEDU | Admiralty Experimental Diving Unit |
| AEIDC | Arctic Environmental Information and Data Center |
| AERC | Association of Ecosystem Research Centers |
| AEROCE | Atmosphere/Ocean Chemistry Experiment |
| AERS | Atlantic Estuarine Research Society |
| AES | Atmospheric Environment Service |
| AESOP | Airborne Experiment to Study Ozone Production |
| AEWC | Alaska Eskimo Whaling System |
| AFC | Automatic Frequency Control |