Środowiskowe Seminarium Fizyki Atmosfery

Witold Rohm, Jarosław Bosy, Jan Kapłon, Tomasz Hadaś, Karina Wilgan, Paweł Hordyniec, Krzysztof Sośnica, Kamil Kaźmierski, Jan SiernyGNSS&Meteo Working Group, Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences. GNSS were not designed and build for remote sensing applications, as of now positioning and navigation are still a corner stone of everyday use of such satellite systems. Surprisingly though, the GNSS data are marked by International Radio Occultation Working Group among top five techniques reducing weather forecasts errors, and the most efficient one in per observation term. There are two major reasons for such high rank: 1) GNSS measurements are all-weather, microwave and based solely on uniform time scale provided by precise atomic clocks observations, 2) high-precision, high-fidelity requirements imposed on the receivers and positioning processing strategies resulted in careful bias removal and uncertainty quantification procedures in place. Currently, there are three major types of observation platforms and associated signal physical effects that are employed in atmosphere remote sensing using GNSS signals: 1)ground-based GNSS observations using permanent networks, where slowing down of signal phase and group velocity is the most dominant effect, 2)space-based limb-looking GNSS observations that record and utilise bending of rays paths, 3)space-based or ground-based reflected signals polarization and group velocity delay with respect to the reference signal is used. The first two play an important role in the GNSS & Meteo research portfolio, as we are at the forefront of ground-based GNSS investigation, advancing troposphere delay estimation techniques in near real time real time, in the zenith direction as well as into the direction of satellite, 4D modelling (GNSS tomography), Numerical Weather Prediction models GNSS assimilation procedures. In collaboration with our Taiwanese partners National Central University and National Space Organisation we also take active role in the COSMIC II research looking into low troposphere radio occultation retrievals, in a near future this collaboration will mature into Joint Processing Centre (PL-TW) established at WUELS.