Remote‐sensing observations of F‐region ion drift velocities using Dynamics Explorer‐2 Doppler measurements of the O⁺(²P) λ732.0 nm emission

Limb‐scan observations of Doppler line profiles from the O⁺(²P) λ732.0 nm emission at F‐region altitudes, made with the Fabry‐Perot interferometer (FPI) on the Dynamics Explorer‐2 (DE‐2) spacecraft, have been analyzed to provide measurements of the meridional component of the ion convection velocity along the instrument line‐of‐sight. The initial DE‐2 results presented here demonstrate the first spaceborne use of the remote‐sensing Doppler technique for measurements of ionospheric convection. The FPI meridional ion drift measurements have been compared with nearly simultaneous in‐situ ion drift measurements from the Retarding Potential Analyzer (RPA) on DE 2. Once allowance is made for the temporal lag between the in‐situ and remote measurements, the results from the two techniques are in good agreement. The results of a simulation study demonstrate that the spaceborne interferometric technique has future utility for 2‐D imaging of the quasi‐instantaneous ion convection pattern.