FG GNSS-Fernerkundung, Navigation und Positionierung

9 Items

Recent Submissions
First evidence of mesoscale ocean eddies signature in GNSS reflectometry measurements

Hoseini, Mostafa ; Asgarimehr, Milad ; Zavorotny, Valery ; Nahavandchi, Hossein ; Ruf, Chris ; Wickert, Jens (2020-02-06)

Feasibility of sensing mesoscale ocean eddies using spaceborne Global Navigation Satellite Systems-Reflectometry (GNSS-R) measurements is demonstrated for the first time. Measurements of Cyclone GNSS (CYGNSS) satellite missions over the eddies, documented in the Aviso eddy trajectory atlas, are studied. The investigation reports on the evidence of normalized bistatic radar cross section ( σ0 ) ...

Multi-GNSS precise position, velocity, and acceleration determination for airborne gravimetry over Antarctica

Min, Li (2020)

The precise knowledge of aircraft position, velocity, and acceleration is a mandatory prerequisite for airborne gravimetry. For the determination of these quantities the Global Navigation Satellite System (GNSS) plays an important role. However, kinematic positioning over Antarctica is a challenging task which is different from positioning in low-latitude regions. The main reason is the sparse ...

Can GNSS reflectometry detect precipitation over oceans?

Asgarimehr, Milad ; Zavorotny, Valery ; Wickert, Jens ; Reich, Sebastian (2018-11-06)

For the first time, a rain signature in Global Navigation Satellite System Reflectometry (GNSS‐R) observations is demonstrated. Based on the argument that the forward quasi‐specular scattering relies upon surface gravity waves with lengths larger than several wavelengths of the reflected signal, a commonly made conclusion is that the scatterometric GNSS‐R measurements are not sensitive to the s...

Using Convective Available Potential Energy (CAPE) and Dew-Point Temperature to Characterize Rainfall-Extreme Events in the South-Central Andes

Ramezani Ziarani, Maryam ; Bookhagen, Bodo ; Schmidt, Torsten ; Wickert, Jens ; de la Torre, Alejandro ; Hierro, Rodrigo (2019-07-08)

The interactions between atmosphere and steep topography in the eastern south–central Andes result in complex relations with inhomogenous rainfall distributions. The atmospheric conditions leading to deep convection and extreme rainfall and their spatial patterns—both at the valley and mountain-belt scales—are not well understood. In this study, we aim to identify the dominant atmospheric condi...

Sea Ice Detection Based on Differential Delay-Doppler Maps from UK TechDemoSat-1

Zhu, Yongchao ; Yu, Kegen ; Zou, Jingui ; Wickert, Jens (2017-07-12)

Global Navigation Satellite System (GNSS) signals can be exploited to remotely sense atmosphere and land and ocean surface to retrieve a range of geophysical parameters. This paper proposes two new methods, termed as power-summation of differential Delay-Doppler Maps (PS-D) and pixel-number of differential Delay-Doppler Maps (PN-D), to distinguish between sea ice and sea water using differentia...

Estimating the Impact of Global Navigation Satellite System Horizontal Delay Gradients in Variational Data Assimilation

Zus, Florian ; Douša, Jan ; Kačmařík, Michal ; Václavovic, Pavel ; Dick, Galina ; Wickert, Jens (2018-12-28)

We 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°. We begin our investigations with simulated observations. In essence, we extract t...

Improving GNSS Zenith Wet Delay Interpolation by Utilizing Tropospheric Gradients: Experiments with a Dense Station Network in Central Europe in the Warm Season

Zus, Florian ; Douša, Jan ; Kačmařík, Michal ; Václavovic, Pavel ; Balidakis, Kyriakos ; Dick, Galina ; Wickert, Jens (2019-03-21)

The Benchmark data set collected within the European COST Action ES1206 has aimed to support the development and validation of advanced Global Navigation Satellite System (GNSS) tropospheric products, in particular high-resolution zenith delays and tropospheric gradients. In this work we utilize this unique data set to show that the interpolation of GNSS Zenith Wet Delays (ZWDs) can be improved...

Evaluating Impact of Rain Attenuation on Space-borne GNSS Reflectometry Wind Speeds

Asgarimehr, Milad ; Wickert, Jens ; Reich, Sebastian (2019-05-03)

The novel space-borne Global Navigation Satellite System Reflectometry (GNSS-R) technique has recently shown promise in monitoring the ocean state and surface wind speed with high spatial coverage and unprecedented sampling rate. The L-band signals of GNSS are structurally able to provide a higher quality of observations from areas covered by dense clouds and under intense precipitation, compar...

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning

Zhou, Feng ; Li, Xingxing ; Li, Weiwei ; Chen, Wen ; Dong, Danan ; Wickert, Jens ; Schuh, Harald (2017-04-03)

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote ...