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Summary Coastal effects observed in the long‐period Sq Solar quist day ranges and short‐period changes over 30 min intervals during magnetic substorms (bays), as recorded at a new magnetic observatory at Visakhapatnam, on the east coast of India, during 1995 in the H, Z and D elements, are analysed and the preliminary results are discussed. The results are compared with those from Alibag and Hyderabad (located more or less at the same latitude) based on simultaneous 1995 records. Short‐period induction vectors are computed and the arrows presented and discussed at the three locations. While the enhancement associated with close proximity to the coast in Sq (Z) at Alibag on the west coast compared to the central inland station of Hyderabad (enhancement of 17–37 per cent) is quite prominent in all three seasons of the year, at Visakhapatnam it is only marginally observed during the d‐season. At bay frequencies, medium‐sized induction arrows point towards the nearest deep‐sea conductive body at both Alibag and Visakhapatnam, while it is towards the southeast with a considerably reduced magnitude at Hyderabad. These induction arrows and the effects on Sq (Z), Sq (H) and Sq (D) ranges are discussed in conjunction with the Parkinson arrows and Sq (Z), Sq (H) and Sq (D) ranges from Margao (west coast)–Dharwar–Bellary–Mahanandi–Chirala (east coast) at the latitude of the 16°N profile of an earlier array experiment, and the two are interpreted together.

A study of the secular variation in the geomagnetic elements H, Z, F and D at Colaba (Bombay)-Alibag for the period 1848-1973, has been made. Fifth degree polynomials are fitted to the data of antiual mean values of H, Z and F, and third degree to D, and the residuals discussed. The trends are also examined at the six Indian observatories using the data for [1960][1961][1962][1963][1964][1965][1966][1967][1968][1969][1970][1971][1972][1973][1974].The increasing trend of Z at Alibag is found to decrease from about 1937, while that of H and F from 1965 at 20-30 nT/year, it being of the same order at Sabhawala and Hyderabad but smaller at the equatorial stations, particularly for Z component. The westward annual change in D swings eastward again around 1965 at all the Indian stations. This reversal of the secular variation trend in India after 1965 emerges as an important regional feature connected with a southward migration of the dip equator in India from 1968.The secular change in D at Alibag (+0.4'/year) is somewhat anomalous in the sense that it is reduced as compared to Hyderabad and other stations (+1.6'/year), probably due to the local magnetic anomaly of the Deccan lavas, and calls for detailed investigations.

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