000196030 001__ 196030
000196030 003__ CZ-ZdVUG
000196030 005__ 20201109113432.0
000196030 041__ $$aeng
000196030 040__ $$aABC039$$bcze
000196030 1001_ $$aDouša,Jan
000196030 24510 $$aEstimating the Impact of Global Navigation Satellite System Horizontal Delay Gradients in Variational Data Assimilation
000196030 300__ $$a16 stran
000196030 5203_ $$aWe developed operators to assimilate Global Navigation Satellite System (GNSS) Zenith Total Delays (ZTDs) and horizontal delay gradients into a numerical weather model. In this study we experiment with refractivity fields derived from the Global Forecast System (GFS) available with a horizontal resolution of 0.5 degrees. We begin our investigations with simulated observations. In essence, we extract the tropospheric parameters from the GFS analysis, add noise to mimic observation errors and assimilate the simulated observations into the GFS 24h forecast valid at the same time. We consider three scenarios: (1) the assimilation of ZTDs (2) the assimilation of horizontal delay gradients and (3) the assimilation of both ZTDs and horizontal delay gradients. The impact is measured by utilizing the refractivity fields. We find that the assimilation of the horizontal delay gradients in addition to the ZTDs improves the refractivity field around 800 hPa. When we consider a single station there is a clear improvement when horizontal delay gradients are assimilated in addition to the ZTDs because the horizontal delay gradients contain information that is not contained in the ZTDs. On the other hand, when we consider a dense station network there is not a significant improvement when horizontal delay gradients are assimilated in addition to the ZTDs because the horizontal delay gradients do not contain information that is not already contained in the ZTDs. Finally, we replace simulated by real observations, that is, tropospheric parameters from a Precise Point Positioning solution provided with the G-Nut/Tefnut software, in order to show that the GFS 24h forecast is indeed improved when GNSS horizontal delay gradients are assimilated in addition to GNSS ZTDs; for the considered station (Potsdam, Germany) and period (June and July, 2017) we find an improvement in the retrieved refractivity of up to 4%.
000196030 655_4 $$ačlánek v odborném periodiku
000196030 7001_ $$aVáclavovic, Pavel
000196030 7001_ $$aKačmařík, Michal
000196030 7001_ $$aDick, Galina
000196030 7001_ $$aWickert, Jens
000196030 7001_ $$aZus, Florian
000196030 7730_ $$92019$$dBasel, Switzerland:[Molecular Diversity Preservation International],2019.$$g11. (1), 16s.$$tRemote Sensing$$x2072-4292$$zISBN
000196030 8564_ $$uhttps://www.mdpi.com/2072-4292/11/1/41
000196030 85642 $$ahttps://www.rvvi.cz/riv?s=rozsirene-vyhledavani&ss=detail&n=0&h=RIV%2F00025615%3A_____%2F19%3AN0000056%21RIV20-MSM-00025615
000196030 910__ $$aABC039
000196030 980__ $$aclanky_vugtk
000196030 985__ $$adousa
000196030 985__ $$ariv
000196030 985__ $$autvar24
000196030 985__ $$avaclavovic