The Earth’s length of day varies on time scales of days or less (due to the atmosphere) to billions of years (due to tides from the moon). In this talk, Professor Richard Holme will focus particularly on intermediate time scales of decades, which are associated with change in motions in Earth’s fluid core. As a result, there is a strong link between such changes and the geomagnetic field.
Professor Holme's recent work has particularly considered intradecadal variations, with a period of about 6 years – these variations are probably caused by motions of the Earth’s solid inner core. He discusses the evidence for such motions, and what further probes they provide concerning the structure and processes of the deep Earth.