L-Band Radiometer Observations of Soil Processes in Boreal and Subarctic Environments
L-Band Radiometer Observations of Soil Processes in Boreal and Subarctic Environments
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DOI：
10.1109/tgrs.2011.2167755
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发表时间：
2012-05
影响因子：
8.2
通讯作者：
K. Rautiainen;J. Lemmetyinen;J. Pulliainen;J. Vehvilainen;M. Drusch;A. Kontu;J. Kainulainen;Jaakko Seppänen
中科院分区：
文献类型：
--
作者：
K. Rautiainen;J. Lemmetyinen;J. Pulliainen;J. Vehvilainen;M. Drusch;A. Kontu;J. Kainulainen;Jaakko Seppänen
2009年11月，欧洲空间局（欧空局）的土壤水分和海洋盐度（SMOS）卫星使命的发射开启了L波段（为射电天文学保留的1.4 GHz波段）全球被动监测的新时代。该使命的主要目标是测量土壤湿度和海面盐度;唯一的有效载荷是使用孔径合成的微波成像辐射计。作为全面校准和验证活动的一部分，已经部署了几个地面L波段辐射计，即所谓的ETH L波段土壤湿度研究辐射计（ELBARA-II）。在本文中，我们分析了一套全面的测量从一个ELBARA-II部署地点在北方北方森林区。本文的重点是检测土壤霜冻的演变（一个相关的主题，例如，研究高纬度地区的碳和甲烷循环）。我们调查的影响，土壤冻/融过程中的L-波段签名，并提出了一个简单的建模方法来分析霜冻深度和观测到的亮温之间的关系。航空观测用于扩展对不同土地覆盖类型的分析。最后，分析了同一时期的第一次SMOS观测。结果表明，土壤冻融过程对土壤的L波段特征有明显的影响。此外，所提出的排放模型是能够与观测到的动态亮温土壤霜冻的增加。
The launch of the European Space Agency (ESA)'s Soil Moisture and Ocean Salinity (SMOS) satellite mission in November 2009 opened a new era of global passive monitoring at L-band (1.4-GHz band reserved for radio astronomy). The main objective of the mission is to measure soil moisture and sea surface salinity; the sole payload is the Microwave Imaging Radiometer using Aperture Synthesis. As part of comprehensive calibration and validation activities, several ground-based L-band radiometers, so-called ETH L-Band radiometers for soil moisture research (ELBARA-II), have been deployed. In this paper, we analyze a comprehensive set of measurements from one ELBARA-II deployment site in the northern boreal forest zone. The focus of this paper is in the detection of the evolution of soil frost (a relevant topic, e.g., for the study of carbon and methane cycles at high latitudes). We investigate the effects that soil freeze/thaw processes have on the L-band signature and present a simple modeling approach to analyze the relation between frost depth and the observed brightness temperature. Airborne observations are used to expand the analysis for different land cover types. Finally, the first SMOS observations from the same period are analyzed. Results show that soil freezing and thawing processes have an observable effect on the L-band signature of soil. Furthermore, the presented emission model is able to relate the observed dynamics in brightness temperature to the increase of soil frost.