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Average Brightness Temperature of Lunar Surface for Calibration of Multichannel Millimeter-Wave Radiometer From 89 to 183 GHz and Data Validation
IEEE Transactions on Geoscience and Remote Sensing ( IF 8.2 ) Pub Date : 2021-02-01 , DOI: 10.1109/tgrs.2020.3000230
Niutao Liu , Ya-Qiu Jin

Calibration of satellite-borne radiometer is a key issue for quantitative remote sensing. Its accuracy depends on the stability of the calibration source. Because of no atmosphere and biological activity, the Moon surface keeps stable in the long term and may be a good candidate for thermal calibration. Observation of microwave humidity sounder (MHS) onboard the NOAA-18 made measurements of the disk-integrated brightness temperature (TB) of the Moon for the phase angle between −80° and 50°. The measurement of NOAA-18 has been studied to validate the TB model of lunar surface. In this article, the near side of the Moon surface is divided into 900 subregions with a span of $6^{\circ }\times 6^{\circ }$ in longitude and latitude. By solving 1-D heat conductive equation with the thermophysical parameters validated by the Diviner data of the Lunar Reconnaissance Orbiter (LRO), the temperature profiles of the regolith media in all 900 subregions are obtained. The loss tangents are inversed from the Chang’e-2 (CE-2) 37-GHz microwave TB data at noontime. Employing the fluctuation–dissipation theorem and the Wentzel–Kramer–Brillouin (WKB) approach, the microwave and millimeter-wave TBs of each subregion are simulated. Then, the weighted average TB can be disk-integrated from 900 TBs of all subregions versus the phase angle. These simulations well demonstrate diurnal TB variation and its dependence upon the frequency channels. It is found that the disk-integrated TB of the Moon in MHS channels is sensitive to the full-width at half-maximum (FWHM) of the deep space view (DSV), which is corrected in our simulation, where the Moon is now taken as an extended target, instead of a point-like object. Simulated integrated TBs are compared with the corrected MHS TB data at 89, 157, and 183 GHz. The simulated TB is well consistent with these MHS TB data at 89 and 183 GHz at various phase angles. But the maximum TB of MHS data at 157 GHz is unusually lower than that of 89 GHz. The influence of the loss tangent, emissivity, and the pointing error is analyzed. Some more careful design to observe the Moon TB and technical parameters, especially the FWHM should be well determined. Our model and numerical simulation provides a tool for TB calibration and validation.

中文翻译:

用于校准 89 至 183 GHz 多通道毫米波辐射计和数据验证的月球表面平均亮度温度

星载辐射计的定标是定量遥感的关键问题。其精度取决于校准源的稳定性。由于没有大气和生物活动,月球表面长期保持稳定,可能是热校准的良好候选者。对 NOAA-18 上的微波湿度探测仪 (MHS) 的观测测量了月球的圆盘积分亮度温度 (TB),相位角在 -80° 和 50° 之间。已经研究了 NOAA-18 的测量以验证月球表面的 TB 模型。在这篇文章中,月球表面的近侧被划分为 900 个子区域,经纬度跨度为 $6^{\circ }\times 6^{\circ }$。通过利用月球勘测轨道器(LRO)的 Diviner 数据验证的热物理参数求解一维导热方程,获得了所有 900 个子区域的风化层介质的温度分布。从嫦娥二号 (CE-2) 37 GHz 微波 TB 数据在中午反转损耗角正切。利用涨落-耗散定理和温策尔-克莱默-布里渊 (WKB) 方法,模拟了每个子区域的微波和毫米波 TB。然后,加权平均 TB 可以从所有子区域的 900 TB 与相位角进行磁盘积分。这些模拟很好地证明了 TB 的昼夜变化及其对频道的依赖性。发现 MHS 通道中的月球盘集成 TB 对深空视图 (DSV) 的半高全宽 (FWHM) 敏感,这在我们的模拟中得到了纠正,现在月球被视为一个扩展目标,而不是一个点状物体。将模拟的集成 TB 与 89、157 和 183 GHz 的校正 MHS TB 数据进行比较。模拟的 TB 与这些 MHS TB 数据在 89 和 183 GHz 的不同相位角下非常一致。但 157 GHz 的 MHS 数据的最大 TB 异常低于 89 GHz。分析了损耗角正切、发射率和指向误差的影响。一些更仔细的设计来观察月球TB和技术参数,特别是FWHM应该很好地确定。我们的模型和数值模拟为 TB 校准和验证提供了工具。将模拟的集成 TB 与 89、157 和 183 GHz 的校正 MHS TB 数据进行比较。模拟的 TB 与这些 MHS TB 数据在 89 和 183 GHz 的不同相位角下非常一致。但 157 GHz 的 MHS 数据的最大 TB 异常低于 89 GHz。分析了损耗角正切、发射率和指向误差的影响。一些更仔细的设计来观察月球TB和技术参数,特别是FWHM应该很好地确定。我们的模型和数值模拟为 TB 校准和验证提供了一个工具。将模拟的集成 TB 与 89、157 和 183 GHz 的校正 MHS TB 数据进行比较。模拟的 TB 与这些 MHS TB 数据在 89 和 183 GHz 的不同相位角下非常一致。但 157 GHz 的 MHS 数据的最大 TB 异常低于 89 GHz。分析了损耗角正切、发射率和指向误差的影响。一些更仔细的设计来观察月球TB和技术参数,特别是FWHM应该很好地确定。我们的模型和数值模拟为 TB 校准和验证提供了工具。并分析指向误差。一些更仔细的设计来观察月球TB和技术参数,特别是FWHM应该很好地确定。我们的模型和数值模拟为 TB 校准和验证提供了工具。并分析指向误差。一些更仔细的设计来观察月球TB和技术参数,特别是FWHM应该很好地确定。我们的模型和数值模拟为 TB 校准和验证提供了工具。
更新日期:2021-02-01
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