A spoiler-like fitting photographed on Kaga

What was the spoiler-like fitting visible in some photographs of Kaga?

Possibly part of an experimental arrangement involving airflow or air purification, although the identification is tentative.

The question points to a roll-bar- or spoiler-like object visible in some photographs of the Japanese carrier Kaga. The identification is tentative and based on memory. The fitting may belong to a period when the ship was used for experiments, including work intended to purify air moving across the relevant area. No firm equipment name is supplied, so the explanation remains provisional.