{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,19]],"date-time":"2026-02-19T06:21:10Z","timestamp":1771482070026,"version":"3.50.1"},"reference-count":28,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2019,5,3]],"date-time":"2019-05-03T00:00:00Z","timestamp":1556841600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Geo.X","award":["SO_087_GeoX"],"award-info":[{"award-number":["SO_087_GeoX"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>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, compared to those signals at higher frequencies from conventional ocean scatterometers. As a result, studying the inner core of cyclones and improvement of severe weather forecasting and cyclone tracking have turned into the main objectives of GNSS-R satellite missions such as Cyclone Global Navigation Satellite System (CYGNSS). Nevertheless, the rain attenuation impact on GNSS-R wind speed products is not yet well documented. Evaluating the rain attenuation effects on this technique is significant since a small change in the GNSS-R can potentially cause a considerable bias in the resultant wind products at intense wind speeds. Based on both empirical evidence and theory, wind speed is inversely proportional to derived bistatic radar cross section with a natural logarithmic relation, which introduces high condition numbers (similar to ill-posed conditions) at the inversions to high wind speeds. This paper presents an evaluation of the rain signal attenuation impact on the bistatic radar cross section and the derived wind speed. This study is conducted simulating GNSS-R delay-Doppler maps at different rain rates and reflection geometries, considering that an empirical data analysis at extreme wind intensities and rain rates is impossible due to the insufficient number of observations from these severe conditions. Finally, the study demonstrates that at a wind speed of 30 m\/s and incidence angle of 30\u00b0, rain at rates of 10, 15, and 20 mm\/h might cause overestimation as large as \u22480.65 m\/s (2%), 1.00 m\/s (3%), and 1.3 m\/s (4%), respectively, which are still smaller than the CYGNSS required uncertainty threshold. The simulations are conducted in a pessimistic condition (severe continuous rainfall below the freezing height and over the entire glistening zone) and the bias is expected to be smaller in size in real environments.<\/jats:p>","DOI":"10.3390\/rs11091048","type":"journal-article","created":{"date-parts":[[2019,5,7]],"date-time":"2019-05-07T03:15:46Z","timestamp":1557198946000},"page":"1048","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Evaluating Impact of Rain Attenuation on Space-borne GNSS Reflectometry Wind Speeds"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9378-1886","authenticated-orcid":false,"given":"Milad","family":"Asgarimehr","sequence":"first","affiliation":[{"name":"Institute of Geodesy and Geoinformation Science, Faculty VI, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"},{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7379-5276","authenticated-orcid":false,"given":"Jens","family":"Wickert","sequence":"additional","affiliation":[{"name":"Institute of Geodesy and Geoinformation Science, Faculty VI, Technische Universit\u00e4t Berlin, 10623 Berlin, Germany"},{"name":"German Research Centre for Geosciences GFZ, 14473 Potsdam, Germany"}]},{"given":"Sebastian","family":"Reich","sequence":"additional","affiliation":[{"name":"Department of Mathematics, University of Potsdam, 14469 Potsdam, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,3]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1109\/MGRS.2014.2374220","article-title":"Tutorial on remote sensing using GNSS bistatic radar of opportunity","volume":"2","author":"Zavorotny","year":"2014","journal-title":"IEEE Geosci. Remote Sens. Mag."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Jin, S., Cardellach, E., and Xie, F. (2014). GNSS Remote Sensing, Springer.","DOI":"10.1007\/978-94-007-7482-7"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"5435","DOI":"10.1002\/2015GL064204","article-title":"Spaceborne GNSS reflectometry for ocean winds: First results from the UK TechDemoSat-1 mission","volume":"42","author":"Foti","year":"2015","journal-title":"Geophys. Res. Lett."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Ruf, C.S., Gleason, S., Jelenak, Z., Katzberg, S., Ridley, A., Rose, R., Scherrer, J., and Zavorotny, V. (2012, January 22\u201327). The CYGNSS nanosatellite constellation hurricane mission. Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Munich, Germany.","DOI":"10.1109\/IGARSS.2012.6351600"},{"key":"ref_5","unstructured":"Ruf, C., Chang, P., Clarizia, M.P., Gleason, S., Jelenak, Z., Murray, J., Morris, M., Musko, S., Posselt, D., and Provost, D. (2016). CYGNSS Handbook, Michigan Publishing."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"4552","DOI":"10.1109\/JSTARS.2016.2614428","article-title":"GEROS-ISS: GNSS reflectometry, radio occultation, and scatterometry onboard the international space station","volume":"9","author":"Wickert","year":"2016","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"13980","DOI":"10.1109\/ACCESS.2018.2814072","article-title":"GNSS Transpolar Earth Reflectometry exploriNg System (G-TERN): Mission Concept","volume":"6","author":"Cardellach","year":"2018","journal-title":"IEEE Access"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Castellv\u00ed, J., Camps, A., Corbera, J., and Alam\u00fas, R. (2018). 3Cat-3\/MOTS Nanosatellite Mission for Optical Multispectral and GNSS-R Earth Observation: Concept and Analysis. Sensors, 18.","DOI":"10.3390\/s18010140"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4534","DOI":"10.1109\/JSTARS.2018.2873241","article-title":"TDS-1 GNSS Reflectometry: Development and Validation of Forward Scattering Winds","volume":"11","author":"Asgarimehr","year":"2018","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1080\/014311697219385","article-title":"Rain generated ring-waves: Measurements and modelling for remote sensing","volume":"18","author":"Bliven","year":"1997","journal-title":"Int. J. Remote Sens."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1029\/2018GL079708","article-title":"Can GNSS Reflectometry Detect Precipitation Over Oceans?","volume":"45","author":"Asgarimehr","year":"2018","journal-title":"Geophys. Res. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Hulst, H.C., and van de Hulst, H.C. (1957). Light Scattering by Small Particles, Courier Corporation.","DOI":"10.1063\/1.3060205"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Contreras, R.F., Plant, W.J., Keller, W.C., Hayes, K., and Nystuen, J. (2003). Effects of rain on Ku-band backscatter from the ocean. J. Geophys. Res. Oceans, 108.","DOI":"10.1029\/2001JC001255"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"951","DOI":"10.1109\/36.841977","article-title":"Scattering of GPS signals from the ocean with wind remote sensing application","volume":"38","author":"Zavorotny","year":"2000","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2733","DOI":"10.1109\/TGRS.2009.2014465","article-title":"An efficient algorithm to the simulation of delay\u2013Doppler maps of reflected global navigation satellite system signals","volume":"47","author":"Camps","year":"2009","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"61","DOI":"10.2528\/PIERB12111509","article-title":"Simulating GNSS-R delay-doppler map of oil slicked sea surfaces under general scenarios","volume":"48","author":"Li","year":"2013","journal-title":"Prog. Electromagn. Res. B"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Gleason, S. (2006). Remote Sensing of Ocean, Ice and Land Surfaces Using Bistatically Scattered GNSS Signals from Low Earth Orbit. [Ph.D. Thesis, University of Surrey].","DOI":"10.1109\/IGARSS.2006.792"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"279","DOI":"10.1016\/0030-4018(79)90353-5","article-title":"Exact multiple scattering of waves from random rough surfaces","volume":"30","author":"Garcia","year":"1979","journal-title":"Opt. Commun."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"15781","DOI":"10.1029\/97JC00467","article-title":"A unified directional spectrum for long and short wind-driven waves","volume":"102","author":"Elfouhaily","year":"1997","journal-title":"J. Geophys. Res. Oceans"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1364\/JOSA.44.000838","article-title":"Measurement of the roughness of the sea surface from photographs of the Sun\u2019s glitter","volume":"44","author":"Cox","year":"1954","journal-title":"JOSA"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"6029","DOI":"10.1109\/TAP.2017.2752219","article-title":"The Transition From Weak to Strong Diffuse Radar Bistatic Scattering From Rough Ocean Surface","volume":"65","author":"Voronovich","year":"2017","journal-title":"IEEE Trans. Antennas Propag."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"2017","DOI":"10.3390\/rs2082017","article-title":"Towards sea ice remote sensing with space detected GPS signals: Demonstration of technical feasibility and initial consistency check using low resolution sea ice information","volume":"2","author":"Gleason","year":"2010","journal-title":"Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Wu, F., Zheng, W., Li, Z., and Liu, Z. (2019). Improving the GNSS-R Specular Reflection Point Positioning Accuracy Using the Gravity Field Normal Projection Reflection Reference Surface Combination Correction Method. Remote Sens., 11.","DOI":"10.3390\/rs11131626"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"3418","DOI":"10.1109\/JSTARS.2017.2674305","article-title":"An assessment of non-geophysical effects in spaceborne GNSS Reflectometry data from the UK TechDemoSat-1 mission","volume":"10","author":"Foti","year":"2017","journal-title":"IEEE J. Sel. Top. Appl. Earth Obs. Remote Sens."},{"key":"ref_25","unstructured":"(2015). ITU-R Recommendation P.838-3, Specific Attenuation Model for Rain for Use In Prediction Methods, International Telecommunication Union. Technical Report."},{"key":"ref_26","unstructured":"Clarizia, P.M., and Zavorotny, V. (2015). Algorithm Theoretical Basis Document Level 2 Wind Speed Retrieval, Cyclone Global Navigation Satellite System (CYGNSS), University of Michigan."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4419","DOI":"10.1109\/TGRS.2016.2541343","article-title":"Wind speed retrieval algorithm for the Cyclone Global Navigation Satellite System (CYGNSS) mission","volume":"54","author":"Clarizia","year":"2016","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"909","DOI":"10.1175\/1520-0493(1985)113<0909:EOTSOP>2.0.CO;2","article-title":"Evolution of the structure of precipitation in Hurricane Allen (1980)","volume":"113","author":"Marks","year":"1985","journal-title":"Mon. Weather Rev."}],"container-title":["Remote Sensing"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/9\/1048\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:48:54Z","timestamp":1760186934000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-4292\/11\/9\/1048"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,5,3]]},"references-count":28,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2019,5]]}},"alternative-id":["rs11091048"],"URL":"https:\/\/doi.org\/10.3390\/rs11091048","relation":{},"ISSN":["2072-4292"],"issn-type":[{"value":"2072-4292","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,5,3]]}}}