The transparency characteristics of Es types

The transparency characteristics of different Es types are examined using the blanketing power, fbEs/foEs. This parameter is used to study the structure, seasonal and solar-cycle variations of the different forms of sporadic-E observed over the Northern Hemisphere. The results of the study are compared with those of previous workers who utilized different methods and substantial agreement is observed. While clear evidence of solar-cycle variations were observed in the Es layers at upper temperate and auroral zones, the Es layers at low-latitude and lower temperate regions showed no evidence of solar-cycle variations.