M₂ and S₂ Tidal Components at Hyderabad

Abstract

As reported earlier¹ the ‘Askania GS.11’ gravimeter has been in continuous operation at Hyderabad as part of the extended programme of earth tide investigations. In its present location the instrument rests on a separate pier with a shallow concrete foundation. The ‘Askania’ tide recording equipment is now being used instead of the photographic registration described earlier². The results of harmonic analysis of tidal data by Pertzev's method for 29 days of observation³ (after elimination of drift by the running mean method⁴) are presented. Considering the latitude of this station (17° 26′ N.) it is expected that only the semidiurnal components would yield reliable results. So far only the two important semidiurnal components, namely, M₂ and S₂, have been evaluated and the corresponding gravimetric factor G has been calculated. In the case of the S₂ wave it should be noted that the results are only a first approximation. Using the values of G obtained, the tidal elastic constants have been calculated and are tabulated in Table 1, where h and k are love numbers, l is the Shida number, D is the diminishing factor, L is Lambert's constant and μ is the rigidity of the earth in 10¹² dynes/cm².