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首页> 外文期刊>Geoscience and Remote Sensing, IEEE Transactions on >Simulation and SMAP Observation of Sun-Glint Over the Land Surface at the L-Band
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Simulation and SMAP Observation of Sun-Glint Over the Land Surface at the L-Band

机译：L波段地面上日光闪烁的模拟和SMAP观测

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We investigate the magnitude of Sun-glint through modeling the Soil Moisture Active Passive (SMAP) brightness temperature (BT). Model results show that the specular reflection of Sun-glint in the L-band can spread over a wide range of view angles due to the roughness and undulation of the land surface and therefore affect SMAP radiometer observations. Due to SMAP's low incidence angle (40°), Sun-glint in the specular direction is never observed, and only the noncoherent component of Sun-glint has influence on SMAP observations. Sun-glint is particularly an issue over wet soil surfaces at low solar zenith angles (SZAs), and caution has to be taken for the terrain effect even for high SZAs, because the local solar incident angle can be significantly changed by the terrain slope and then the specular reflection of Sun-glint can be viewed by SMAP. Model results also show that BT in V-pol is less contaminated by Sun-glint than that in H-pol. During an intense solar radio burst, it was found that the land surface BT in H-pol increased by 50 K in the forward scattering direction from the SMAP observation. This is roughly equivalent to 1 K increment by every 100 solar flux units on a dry soil and/or dense vegetation. When the solar activity is quiet in 2015, the Sun-glint from both wet land and ocean surfaces can reach up to 10 K in the SMAP L1B BT product. This paper suggests that BT observations around the solar specular direction should be masked for soil moisture retrieval at the L-band.
机译：我们通过对土壤水分主动被动（SMAP）亮度温度（BT）进行建模，研究了日照强度。模型结果表明，由于陆地表面的粗糙度和起伏，L波段太阳闪烁体的镜面反射可以在很宽的视角范围内传播，因此会影响SMAP辐射计的观测。由于SMAP的入射角低（40°），因此从未观察​​到镜面方向上的Sun-glint，只有Sun-glint的非相干分量会影响SMAP观测。在低太阳天顶角（SZAs）的湿润土壤表面上，太阳眩光是一个特别大的问题，即使对于高SZA，也要谨慎对待地形效应，因为局部太阳入射角会因地形坡度和然后可以通过SMAP观察到Sun-glint的镜面反射。模型结果还表明，V-pol中的BT受到Sun-glint的污染要比H-pol中的少。在强烈的太阳射电爆发期间，从SMAP观测发现，H-pol中的陆地表面BT在向前散射方向上增加了50K。在干燥的土壤和/或茂密的植被上，这大约等于每100个太阳光通量单位增加1K。当2015年太阳活动平静时，SMAP L1B BT产品的湿地和海洋表面的日照都可以达到10K。本文建议在太阳镜面方向周围的BT观测应该被遮盖，以在L波段恢复土壤水分。

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