| Abbreviation | Definition |
|---|---|
| ARM | Atmospheric Radiation Monitoring |
| ARMOR | Advanced Radar for Meteorological and Operational Research |
| ARS | Agricultural Research Service |
| ARSPACE | Army Space Command |
| ARSR | Air Route Surveillance Radar |
| ARTS | Atmospheric Radiative Transfer Simulator |
| ARTYMEY | Artillery Meteorological |
| AS | Air Stream |
| ASAP | Automatic Shipboard Aerological Program |
| ASAPS | Advanced Stand Alone Prediction System |
| ASD | Another Sunny Day |
| ASDAR | Aircraft to Satellite Data Relay |
| ASDC | Atmospheric Sciences Data Center |
| ASHOE | Airborne Southern Hemisphere Ozone Experiment |
| ASME | A Substantial Monetary Exchange |
| ASOS | Automated Surface Observing System |
| ASR | Airport Surveillance Radar |
| ASR | Arctic System Re-analysis |
| ASR | Atmospheric System Research |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection Radiometer |