Comparsion of different microwave radiometric calibration techniques
Comparsion of different microwave radiometric calibration techniques
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不同微波辐射校准技术的比较
DOI：
10.1109/igarss.2004.1369937
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
R. D. Roo
中科院分区：
文献类型：
--
作者：
K. Tien;J. Judge;R. D. Roo
在本文中，我们比较了三种通常用于校准微波辐射计的技术，并了解其设计稳定性。第一种校准技术利用冷负荷和热负荷测量来构建校准曲线。在我们的案例中，我们将天空作为冷负荷，将环境温度下的微波吸收器作为热负荷。第二种校准技术利用测量不同天顶角的天空亮度温度来确定校准曲线所需的大气不透明度。第三种校准技术利用测量内部参考负载和微控制器在两个极化辐射计内估计系统增益波动和接收机噪声温度。在第一次微波水和能量平衡实验（MicroWEX-1）中，我们每两周对我们的佛罗里达大学c波段微波辐射计（UFCMR）进行校准。我们发现，第一种和第三种技术产生的校准结果相似，标准差为1开尔文/伏特。而第三种方法在整个实验过程中最稳定，标准偏差最小，在MicroWEX-1期间H-pol校准曲线斜率为2.41开尔文/伏特，V-pol校准曲线斜率为7.46开尔文/伏特
In this paper we compare three techniques typically used for calibrating a microwave radiometer and understanding its design stability. The first calibration technique utilizes cold and hot load measurements to construct calibration curves. For our case, we used sky as the cold load and microwave absorber at ambient temperature as hot load. The second calibration technique utilizes measurements of the brightness temperature of the sky at various zenith angles to determine the atmospheric opacity needed for the calibration curves. The third calibration technique utilizes measurements of internal reference load and micro-controller inside the radiometer at both polarizations to estimate the system gain fluctuations and the receiver noise temperatures. We calibrated our University of Florida C-band Microwave Radiometer (UFCMR) every two weeks during the first Microwave Water and Energy Balance Experiment (MicroWEX-1). We found that, the first and third techniques produced similar calibration results with 1 Kelvin/volt standard deviation. However, the third technique was the most stable during the entire experiment with the smallest standard deviations which were 2.41 Kelvin/volt for the slope of the calibration curves at H-pol and 7.46 Kelvin/volt for the slope of the calibration curves at V-pol during MicroWEX-1