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首页> 外文期刊>IEEE Transactions on Geoscience and Remote Sensing. >Impact of Backscatter Variations Over Water Bodies on Coarse-Scale Radar Retrieved Soil Moisture and the Potential of Correcting With Meteorological Data
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Impact of Backscatter Variations Over Water Bodies on Coarse-Scale Radar Retrieved Soil Moisture and the Potential of Correcting With Meteorological Data

机译：水体上背向散射变化对粗尺度雷达获取的土壤水分的影响以及气象数据校正的潜力

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摘要

The Northern Hemisphere is, to a large extent, underlain by permafrost, which is prone to thawing due to rapid warming in the Arctic during the 21st century. In this context, satellite-derived soil moisture data are valuable for modeling purposes. Assessing the applicability of such data at high latitudes is essential but has, until recently, been given little attention. Recent studies have pointed out that seasonal land cover variations and the presence of small water bodies, which are typical in the Arctic, can cause complications for soil moisture retrieval. Here, it is hypothesized that a bias related to water fraction is caused by variations in the water surface roughness. The impact is quantified for the Metop Advanced Scatterometer by investigations of the higher spatial resolution synthetic aperture radar (SAR) data acquired by ENVISAT Advanced SAR over 11 sites across the Siberian Arctic. The bias calculated as an average over time can be explained by the lake fraction: a water fraction higher than 20% causes a bias of more than 10% relative surface soil moisture. This can, to a great extent, be attributed to wind, based on which a bias correction was developed. The correction was applied and evaluated with in situ soil moisture data, which were available from one of the sites: the Lena Delta. Weak results are obtained because water surfaces correspond mainly to rivers at this site. Variations in discharge, water height, and streams may therefore also affect the water surface roughness.
机译：北半球在很大程度上被永久冻土所覆盖，由于21世纪北极地区的迅速升温，该永久冻土易于融化。在这种情况下，卫星衍生的土壤水分数据对于建模目的是有价值的。评估此类数据在高纬度的适用性至关重要，但直到最近还很少引起关注。最近的研究指出，季节性的土地覆盖变化和北极地区典型的小水体的存在可能会导致土壤水分获取的复杂化。这里，假设与水分数有关的偏差是由水表面粗糙度的变化引起的。通过调查ENVISAT Advanced SAR在西伯利亚北极地区11个地点获得的更高空间分辨率的合成孔径雷达（SAR）数据，对Metop Advanced散射仪的影响进行了量化。随时间推移计算​​为平均值的偏差可以用湖泊分数来解释：高于20％的水分数导致相对于表层土壤相对湿度的偏差超过10％。这在很大程度上可以归因于风，在此基础上发展了偏差校正。应用校正并利用原地土壤湿度数据进行评估，这些数据可从以下站点之一获得：Lena Delta。由于该地点的水面主要对应于河流，因此获得的结果较弱。因此，排水量，水高和水流的变化也可能影响水的表面粗糙度。

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