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Geoid height anomalies around the Iceland hotspot in an area extending between 50°W to 14°E and 45°N to 72°N have been investigated to search for evidence of an upper mantle thermal anomaly. After removing wavelengths longer than 3800 km, the effect of the cooling lithosphere was eliminated by low-pass filtering of age data and applying the boundary model. The effects of the various platforms and swells in the North Atlantic were removed by an Airy model, since the geoid-to-topography ratio is lower than 1.5 m km-1 for all areas of elevated topography independent of their origin. The residual geoid shows a large positive anomaly with a steep constant slope towards a location (north)west of Iceland beneath Greenland. The amplitude of the anomaly can be estimated to at least 8 m. The geoid-to-topography ratio reaches a value of 7 m km-1 which is in good agreement with a plume-related anomaly.
(Click the maps to go to the data download pages) When using the geoid models, please be advised that GEOID12B should supersede previous models GEOID12 and GEOID12A. GEOID12B is identical to GEOID12A everywhere, except in Puerto Rico and Virgin island region. GEOID12 is a refined hybrid model of the geoid in the United States and other territories, which supersedes the previous models GEOID09, GEOID06, GEOID03, GEOID99, GEOID96, GEOID93, and GEOID90. This model is intended for converting between the NAD83 ellipsoid reference frame resulting from the National Adjustment of 2011 and vertical datums NAVD88, GUVD04, ASVD02, NMVD03, PRVD02 and VIVD09.