DEPTH OF NON-CONDUCTING LAYER IN THE INDIAN-OCEAN REGION AROUND THUMBA, DERIVED FROM INSITU INVESTIGATIONS OF EQUATORIAL ELECTROJET .2.

The height integrated current density in the electrojet over Thumba has been measured between the years 1966 and 1976 on nine different occasions by rocket-borne magnetometers. Using this data and the H variation data from a spread of ground magnetic stations in the region of the electrojet, the depth of the non-conducting layer has been evaluated. The results are compared with the results obtained from POGO and Kosmos 321 satellite experiments. It is shown that the depth of non-conducting layer in the region around Thumba is 230 ±20 km. Using the above data, the internal and the external contributions to the diurnal variation of geomagnetic field observed at the ground have been evaluated. © 1979, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.