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.