Table 1. Dynasonde ionograms are classified into four categories

Tpye	Description
Unavailable	No echoes are detected by the Dynasonde analysis.
Sporadic E	F-region ionosphere was blanketed by the sporadic-E like structure at lower altitudes.
Needs Reprocessing	Trace selection procedure was not properly performed in the autonomous Dynasonde analysis.
Available	Electron density profiles are properly produced.