Opportunity of diagnostics of elektric fields in day and night sectors of the ionosphere

Correlation communications of electric fields in a polar ionosphere with indices of magnetic activity are investigated. Are established, that there are strong correlation communications between a difference of electric potentials in day sector and PCN, also a difference of electric potentials in night sector and |AL|. The opportunity of use of indices AL and PCN for diagnostics of electric fields in day and night sectors of a polar ionosphere during a substorm is shown.