A new global model for P wave speed variations in Earth's mantle

We document our tomographic method and present a new global model of three‐dimensional (3‐D) variations in mantle P wave velocity. The model is parameterized by means of rectangular cells in latitude, longitude, and radius, the size of which adapts to sampling density by short‐period (1 Hz) data. The largest single data source is ISC/NEIC data reprocessed by Engdahl and coworkers, from which we use routinely picked, short‐period P , P g, Pn , pP , and pwP data (for earthquakes during the period 1964∼2007). To improve the resolution in the lowermost and uppermost mantle, we use differential times of core phases ( PKP AB − PKP DF , PKP AB − PKP BC , P diff − PKP DF ) and surface‐reflected waves ( PP‐P ). The…