Modelling of Episodic-Transient Signals in Measurements of Large Ring Lasers

点击翻译按钮获取中文摘要

Ring lasers measure rotations of the observation platform absolute, instantaneously and in high temporary resolution. These properties make ring lasers a promising tool for measuring short term fluctuations in Earth rotation. Modern large ring lasers show a very small drift in observation intervals reaching from only a few minutes up to several days. For the G ring laser in Wettzell we have now achieved a measurement resolution as good as 10-8 of the rotation rate of the Earth. Because of this high instrumental resolution there are not only the expected periodical geophysical signals visible in the timeseries of the measurement. We also start to see non-periodic and transient signals of unidentified origin. One possible cause with local or regional effect could be result of horizontal wind-pressure along geographical structures ¿ in this case the alpine mountain belt in central Europe. A central part of this research proposal therefore is the modeling of horizontal deformations of the Earth crust caused by windload and the effect this will have on our ring laser measurements. The identification of such non-global rotational components is very important for the interpretation of timeseries of large ring lasers with respect to Earth rotation variations.