Ground-based multichannel microwave radiometers (GMRs) can observe the atmospheric microwave radiation brightness temperature at K-bands and V-bands and provide atmospheric temperature and humidity profiles with a relatively high temporal resolution. Currently, microwave radiometers are operated in many countries to observe the atmospheric temperature and humidity profiles. However, a theoretical analysis showed that a radiometer can be used to observe solar radiation. In this work, we improved the control algorithm and software of the antenna servo control system of the GMR so that it could track and observe the sun and we use this upgraded GMR to observe solar microwave radiation. During the observation, the GMR accurately tracked the sun and responded to the variation in solar radiation. Furthermore, we studied the feasibility for application of the GMR to measure the absolute brightness temperature (TB) of the sun. The results from the solar observation data at 22.235, 26.235, and 30.000 GHz showed that the GMR could accurately measure the TB of the sun. The derived solar TB measurements were 9950 ± 334, 10,351 ± 370, and 9217 ± 375 K at three frequencies. In a comparison with previous studies, we obtained average percentage deviations of 9.1%, 5.3%, and 4.5% at 22.235, 26.235, and 30.0 GHz, respectively. The results demonstrated that the TB of the sun retrieved from the GMR agreed well with the previous results in the literature. In addition, we also found that the GMR responded to the variation in sunspots and a positive relationship existed between the solar TB and the sunspot number. According to these results, it was demonstrated that the solar observation technique can broaden the field usage of GMR.

中文翻译：

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使用地基多通道微波辐射计测量太阳绝对亮度温度

地基多通道微波辐射计（GMR）可以观测K波段和V波段的大气微波辐射亮温，提供具有较高时间分辨率的大气温湿度廓线。目前，许多国家使用微波辐射计来观测大气温度和湿度分布。然而，理论分析表明，辐射计可用于观测太阳辐射。在这项工作中，我们改进了 GMR 天线伺服控制系统的控制算法和软件，使其可以跟踪和观测太阳，我们使用这个升级后的 GMR 来观测太阳微波辐射。在观测过程中，GMR 准确跟踪太阳并响应太阳辐射的变化。此外，我们研究了应用 GMR 测量太阳绝对亮温 (TB) 的可行性。22.235、26.235和30.000 GHz的太阳观测数据结果表明，GMR可以准确测量太阳的TB。在三个频率下，衍生的太阳 TB 测量值为 9950 ± 334、10,351 ± 370 和 9217 ± 375 K。与之前的研究相比，我们在 22.235、26.235 和 30.0 GHz 下分别获得了 9.1%、5.3% 和 4.5% 的平均百分比偏差。结果表明，从 GMR 中检索到的太阳 TB 与文献中的先前结果非常吻合。此外，我们还发现GMR对太阳黑子的变化有反应，太阳TB与太阳黑子数之间存在正相关关系。根据这些结果，