Which ASOS level includes major hubs supplemented with human observers?

The designation of ASOS levels specifies the capabilities and operational methodologies for Automated Surface Observing Systems, particularly in terms of how they operate and the degree of human oversight involved. Level A, which includes major hubs supplemented with human observers, is designed for environments where comprehensive weather observation is critical. At this level, automated systems perform regular data collection, but human observers are present to ensure accuracy, particularly during adverse weather conditions or to provide real-time analysis that might not be captured adequately by automation alone.

This setup allows for enhanced reliability and real-time decision-making, which is vital for aviation safety and meteorological reporting. The presence of human observers helps to confirm automated data and offers an additional layer of scrutiny, especially when interpreting complex weather phenomena. This integration of human expertise with automated measurements distinguishes Level A from the other levels, which may either rely purely on automation or have varying degrees of observer involvement.