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首页> 外文期刊>Surveys in Geophysics: An International Review Journal of Geophysics and Planetary Sciences >Global Snow Mass Measurements and the Effect of Stratigraphic Detail on Inversion of Microwave Brightness Temperatures
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Global Snow Mass Measurements and the Effect of Stratigraphic Detail on Inversion of Microwave Brightness Temperatures

机译：全球雪量测量和地层细节对微波亮度温度反演的影响

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摘要

Snow provides large seasonal storage of freshwater, and information about the distribution of snow mass as snow water equivalent (SWE) is important for hydrological planning and detecting climate change impacts. Large regional disagreements remain between estimates from reanalyses, remote sensing and modelling. Assimilating passive microwave information improves SWE estimates in many regions, but the assimilation must account for how microwave scattering depends on snow stratigraphy. Physical snow models can estimate snow stratigraphy, but users must consider the computational expense of model complexity versus acceptable errors. Using data from the National Aeronautics and Space Administration Cold Land Processes Experiment and the Helsinki University of Technology microwave emission model of layered snowpacks, it is shown that simulations of the brightness temperature difference between 19 and 37 GHz vertically polarised microwaves are consistent with advanced microwave scanning radiometer-earth observing system and special sensor microwave imager retrievals once known stratigraphic information is used. Simulated brightness temperature differences for an individual snow profile depend on the provided stratigraphic detail. Relative to a profile defined at the 10-cm resolution of density and temperature measurements, the error introduced by simplification to a single layer of average properties increases approximately linearly with snow mass. If this brightness temperature error is converted into SWE using a traditional retrieval method, then it is equivalent to ±13 mm SWE (7 % of total) at a depth of 100 cm. This error is reduced to ±5.6 mm SWE (3 % of total) for a two-layer model.
机译：雪提供了大量季节性淡水存储，而有关雪量分布的信息（雪当量（SWE））对于水文规划和检测气候变化影响非常重要。重新分析，遥感和建模的估计之间仍然存在较大的地区分歧。吸收被动微波信息可以改善许多地区的SWE估算，但是吸收必须说明微波散射如何取决于雪地层。物理积雪模型可以估计积雪地层，但是用户必须考虑模型复杂度与可接受误差之间的计算开销。利用美国国家航空航天局冷陆过程实验和赫尔辛基工业大学分层积雪的微波发射模型的数据，结果表明，垂直极化微波在19 GHz和37 GHz之间的亮度温差的模拟与高级微波扫描是一致的一旦使用了已知的地层信息，就可以使用辐射计-地球观测系统和特殊的传感器微波成像仪进行检索。单个雪廓的模拟亮度温差取决于所提供的地层细节。相对于以10厘米的密度和温度测量分辨率定义的剖面，简化为单层平均属性所引入的误差随积雪量线性增加。如果使用传统的检索方法将此亮度温度误差转换为SWE，则在100 cm的深度处等效于±13 mm SWE（占总数的7％）。对于两层模型，此误差减小到±5.6 mm SWE（占总误差的3％）。

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