气候变化领域集成服务门户(CCPortal): Characterization of rain impact on L-Band GNSS-R ocean surface measurements

CCPortal

DOI	10.1016/j.rse.2019.111607
	Characterization of rain impact on L-Band GNSS-R ocean surface measurements
	Balasubramaniam R.; Ruf C.
发表日期	2020
ISSN	00344257
卷号	239
英文摘要	Earth remote sensing using reflected GNSS signals is currently an emerging trend especially in ocean surface wind measurements. Unlike the existing scatterometer missions, GNSS-R uses L-Band navigation signals that can penetrate through clouds and rain. Rain may have a negligible impact on the transmitted signal in terms of path attenuation at this wavelength. However, there are other effects due to rain, such as changes in surface roughness and rain induced local winds, which can significantly alter the measurements. Currently, there is no observation-based characterization of all possible impacts of rain on radar forward scatter, which is the nature of operation of GNSS-R missions. In this study, we propose a 3-fold rain model which accounts for attenuation, surface effects of rain and rain induced local winds. We utilize the large dataset of measurements made by the CYGNSS mission to separate these different effects of rain. The attenuation model suggests that a total of at least 96% transmissivity exists at L-Band up to a rain rate of 30 mm/h. A perturbation model is used to characterize the other rain effects. It suggests that rain is accompanied by an overall reduction in the scattering cross-section of the ocean surface and, most importantly, this effect is observed only up to surface wind speeds of 15 m/s, beyond which the gravity capillary waves dominate the scattering in the quasi-specular direction. Observations also suggest that, at very low wind speeds, the lower bound on wavenumber of the portion of the surface roughness spectrum that influences the measurements deviates from the geometric optics approximation normally used. This work binds together several rain-related phenomena and enhances our overall understanding of rain effects on GNSS-R measurements. © 2020 The Authors
英文关键词	CYGNSS; GNSS-R; Radar cross-section; Rain
语种	英语
scopus关键词	Large dataset; Meteorological instruments; Radar cross section; Remote sensing; Salinity measurement; Surface measurement; Surface roughness; Wind; CYGNSS; Earth remote sensing; Geometric optics approximation; GNSS-R; Gravity capillary waves; Ocean surface winds; Roughness spectrum; Scattering cross section; Rain; data set; GNSS; remote sensing; scatterometer; sea surface; surface roughness; surface wind; transmissivity
来源期刊	Remote Sensing of Environment
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179457
作者单位	University of Michigan, Ann Arbor, MI, United States
推荐引用方式 GB/T 7714	Balasubramaniam R.,Ruf C.. Characterization of rain impact on L-Band GNSS-R ocean surface measurements[J],2020,239.
APA	Balasubramaniam R.,&Ruf C..(2020).Characterization of rain impact on L-Band GNSS-R ocean surface measurements.Remote Sensing of Environment,239.
MLA	Balasubramaniam R.,et al."Characterization of rain impact on L-Band GNSS-R ocean surface measurements".Remote Sensing of Environment 239(2020).