****************************************************************************** dorismail 08-Dec-2020 20:15:54 Message No 1254 ****************************************************************************** Author: Couhert Alexandre Subject: EGU2021, Session G2.4: Precise Orbit Determination for Geodesy and Dear colleagues, We would like to draw your attention to the session "G2.4 Precise Orbit Det= ermination for Geodesy and Earth Science" organized at the upcoming virtual= General Assembly of the European Geosciences Union (vEGU21), taking place = from April 19 - 30, 2021. Session description: Precise orbit determination is of central importance for many applications = of geodesy and earth science. The challenge is to determine satellite orbit= s in an absolute sense at the centimeter or even sub-centimeter level, and = at the millimeter or even sub-millimeter level in a relative sense. New con= stellations of GNSS satellites are currently being completed and numerous p= osition-critical missions (e.g. altimetry, gravity, SAR and SLR missions) a= re currently in orbit. All together outstanding data are available offering= new opportunities to push orbit determination to the limit and to explore = new applications. This session aims to make accessible the technical challenges of orbit dete= rmination and modelling to the wider community and to quantify the nature o= f the impact of dynamics errors on the various applications. Contributions are solicited but not limited to the following areas: (1) pre= cise orbit determination and validation; (2) satellite surface force modell= ing; (3) advances in modelling atmospheric density and in atmospheric gravi= ty; (4) advances in modelling earth radiation fluxes and their interaction = with space vehicles; (5) analysis of changes in geodetic parameters/earth m= odels resulting from improved force modelling/orbit determination methods; = (6) improvements in observable modelling for all tracking systems, e.g. SLR= , DORIS, GNSS and their impact on orbit determination; (7) advances in comb= ining the different tracking systems for orbit determination; (8) the impac= t of improved clock modelling methods/space clocks on precise orbit determi= nation; (9) advances in modelling satellite attitude. Please consider submitting an abstract to this dedicated orbit session. The deadline for abstract submission is January 13, 2021 at 13:00 CET. We are looking forward to your contribution. On behalf of the convenors of session G2.4, Adrian J=E4ggi Co-conveners: Alexandre Couhert, Urs Hugentobler, Heike Peter, Jose van den= IJssel