El Niño effects on earth rotation parameters from LAGEOS and LARES orbital analysis

Earth rotation, besides external actions due to other bodies in the solar system, is influenced by internal mass redistributions, including its atmospheric and water envelope. EI Nifio-Southern Oscillation (ENSO) is one such event characterized by sea level change in the eastern part of the Pacific Ocean due to an increase of the temperature by about 2°C. ENSO is manifested with irreguIar periodicity and with different strength. SateIIite Laser Ranging (SLR) to orbiting satellites such as LAGEOS and LARES in conjunction with the other geodedic techniques, such as GNSS and Very Long Baseline Interferometry (VLBI), allow very accurate determination of the center of mass and rotation vector of the Earth. The paper will report on the experimental vaIues of the Earth orientation parameters and in particuIar of the center of mass and the Iength of the day with particuIar reference to signatures due to last ENSO event ended in 2016.