[G06-P] Poster

[G06-P-04] Ray-traced radio occultation profiles during tropical cyclones

^○Pawel Hordyniec¹, Cheng-Yung Huang², Witold Rohm¹ (1.Wroclaw University of Environmental and Life Sciences, Institute of Geodesy and Geoinformatics, Wroclaw, Poland, 2.National Space Organization, HsinChu, Taiwan)

We used Global Forecast System (GFS) model as an environment to propagate microwave signal along occultation plane between GNSS satellite and low-Earth orbiter in order to assess ray-traced radio occultation atmospheric products. We restored 2-dimensional structure of bending angle and associated excess phase by means of geometry optics in non-spherically symmetric atmosphere neglecting out-of-plane components. Since the spherical symmetry assumption is commonly applied for retrieval of radio occultation profiles, we also considered the GFS refractivity above tangent point to be consistent with medium along propagation paths. The Abel transform is used to prove correct simulations. Above troposphere, where strong horizontal gradients usually are not observed, we were able to estimate signal amplitude under geometry optics. However, tropospheric signal to noise ratio needs to be resolved in wave optics due to multipath effect based on simulated bending angle profiles. The radio occultation data provided by COSMIC Data Analysis and Archive Center (CDAAC) in atmPrf and wetPrf products were considered as an additional source of reference for bending angle as well as atmPhs containing amplitude and phase data. To demonstrate capability of the ray-tracer, simulations were conducted under severe weather conditions on the example of tropical cyclones that passed through Taiwan in 2016. In such events, significant horizontal irregularities can be observed, hence we calculated and analyzed residuals between spherically symmetric and asymmetric ray-traced parameters together with amplitude variations.