Which system provides up-to-minute surface observations through digitized voice broadcasts?

The Automated Surface Observing System (ASOS) is designed to provide real-time surface weather observations. It collects and processes weather data, including temperature, humidity, wind speed and direction, precipitation, and visibility. This data is crucial for pilots and air traffic control to make informed decisions regarding flight operations. ASOS transmits this information through digitized voice broadcasts and automated reports, ensuring that users receive timely and accurate weather updates.

In contrast, the Automated Terminal Information Service (ATIS) is primarily used at airports to deliver essential information such as weather, active runways, and other pertinent information to pilots before takeoff and landing, but it does not focus solely on surface observations. The Aviation Routine Weather Report (METAR) provides standardized reports about current weather conditions, but it is not delivered via digitized voice broadcasts in the manner that ASOS is. Lastly, the Aviation Area Forecast (FA) provides a forecast for significant weather conditions over a larger area and is not focused on up-to-the-minute observations. Thus, ASOS is the correct choice for providing timely surface observations through digitized voice broadcasts.