A correlative study of magnetic flux transfer in the magnetosphere

The applied magnetic flux (Phi/sub a/p) of the southward component of the interplanetary magnetic field in GSM coordinates (B/sub z//sup -/) which impinges upon the sunward magnetopause has been compared with the time integral of the auroral AL index during 56 intervals within a 3-month period in 1969 when interplanetary records from Heos 1 and Explorer 35 were available. The periods of magnetic activity chosen were those for which B/sub z/>0 and AL<20..gamma.. at the beginning and end of the interval. It was found that for these intervals, ..integral.. AL dtproportionalPhi/sub a/p with a correlation coefficient of 0.94. In addition, the empirical relationships between magnetic flux transfer, the applied southward flux, and ..integral.. AL dt arrived at by Holzer and Slavin (1978) on the basis of expansions and contractions of the forward magnetosphere observed with Ogo 5 are reexamined and improved. With these expressions describing the bulk rates of magnetic flux transfer within the magnetosphere a lower limit of 0.2 +- 0.1 on the local reconnection efficiency at the magnetopause is calculated.

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