Wind speed observation over oceans with GNSS-Reflectometry
- Comparison of TDS-1 and buoys wind speed by Tropical Atmosphere Ocean (TAO) in the Pacific, moored array in the Tropical Atlantic (PIRATA) and the moored array for African–Asian–Australian Monsoon Analysis and Prediction (RAMA). The data set covers period from November 2014 to March 2016. The total number of observations are 2921 collocated within 60 km and 15 min.
- © M. Asgarimehr (GFZ)
Current meteorological models dramatically fail to
resolve the fast storm growth evolutions in severe weather events.
This fact is caused by the lack of high-resolution observational data
in the current operational Data Assimilation (DA) systems and
deficiencies in the collection of real-time data from inner core of
hurricanes. This fact is due to the heavy clouds and intense
precipitations. GNSS scatterometry can be structurally able to provide
the unaffected wind information due to the none-sensitivity to
atmospheric attenuation, while other scatterometers are affected
during such phenomena [Portabella et al., 2012]. Zavorotny and
Voronovich  theoretically have modeled the power of a scattered
GPS signal as a function of geometrical properties, wind speed and
direction. The figure compares the TDS-1 and ocean buoys wind
By the supports from geoscientific Geo.X network  in the German Berlin-Potsdam region, the Young Academy Fellow program, this research project addresses the retrieval of wind information by GNSS-R techniques. The errors will be characterized [Asgarimehr et al., 2017] and GNSS-R data assimilation into weather models and the improvements in storm scale predictions will be evaluated. These investigations have started by studying TechDemoSat-1 (TDS-1) GNSS-R based winds. The eight-satellite GNSS-R mission CYGNSS (Cyclone Global Navigation Satellite System , launch: 19 December, 2016) data allow the continuation of the study with 630,000 DDMs per 48 hours.
 Asgarimehr, M., J. Wickert, and S. Reich (2017), Rain Effects on TechDemoSat-1 wind speeds: Toward improved GNSS Scatterometry, Submitted paper to IEEE Geoscience and Remote Sensing Letters (under review).
 Portabella, M., A. Stoffelen, W. Lin, A. Turiel, A. Verhoef, J. Verspeek, and J. Ballabrera-Poy (2012), Rain effects on ASCAT-retrieved winds: Toward an improved quality control, IEEE Transactions on Geoscience and Remote Sensing, 50(7), 2495-2506 .
 Unwin, M., P. Jales, J. Tye, C. Gommenginger, G. Foti, and J. Rosello, Spaceborne GNSS-Reflectometry on TechDemoSat-1: Early Mission Operations and Exploitation, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 9, 10, pp. 4525-4539, doi: 10.1109/JSTARS.2016.2603846, 2016.
 Zavorotny, V. U., and A. G. Voronovich (2000), Scattering of GPS signals from the ocean with wind remote sensing application, IEEE Transactions on Geoscience and Remote Sensing, 38(2), 951-964 .