Verifying the body tide at the Canary Islands using tidal gravimetry observations

Abstract

Gravity tide records from El Hierro, Tenerife and Lanzarote Islands (Canarian Archipelago) have been analyzed and compared to the theoretical body tide model (DDW) of Dehant el al. (1999). The use of more stringent criterion of tidal analysis using VAV program allowed us to reduce the error bars by a factor of two of the gravimetric factors at Tenerife and Lanzarote compared with previous published values. Also, the calibration values have been revisited at those sites. Precise ocean tide loading (OTL) corrections based on up-to-date global ocean models and improved regional ocean model have been obtained for the main tidal harmonics O 1, K 1, M 2, S 2. We also point out the importance of using the most accurate coastline definition for OTL calculations in the Canaries. The remaining observational errors depend on the accuracy of the calibration of the gravimeters and/or on the length of the observed data series. Finally, the comparison of the tidal observations with the theoretical body tide models has been done with an accuracy level of 0.1% at El Hierro, 0.4% at Tenerife and 0.5% at Lanzarote.