Search

Description of the systematic error model applied during the ILRS reanalysis for submission to ITRF2020.

The GGOS-imposed requirements to be met by all geodetic techniques per decade are very stringent: 1 mm position and 0.1 mm/y temporal stability. We are an order of magnitude worse today due to a poor ground segment and limitations in the space segment. The unavailability of daily sessions on SLR targets results in loss of geometry leading to lower accuracy and resolution of SLR products. The limited (4) satellites used in ITRF development led to several attempts to launch better-designed targets, leading to ASI’s LARES (LAser RElativity Satellite), launched by ESA in 2012. Along with the LAGEOS’ and Etalon it will now contribute to ITRF2020. Furthermore, ASI approved the development of LARES-2 with a launch in late 2019.

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.