Millimeter Wavelength Brightness Fluctuations of the Atmosphere above the South Pole
Millimeter Wavelength Brightness Fluctuations of the Atmosphere above the South Pole
复制标题
南极上空大气的毫米波长亮度波动
DOI：
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发表时间：
2004
期刊：
影响因子：
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通讯作者：
Chaohua Kuo
中科院分区：
文献类型：
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作者：
R. Bussmann;R. Bussmann;W. Holzapfel;Chaohua Kuo
我们报告了用Arcminute宇宙学辐射热计阵列接收机（ACBAR）对南极上空大气产生的毫米波长亮度波动的测量结果。这些数据跨越了2002年的南方冬季，当时ACBAR被安装在南极的蝰蛇望远镜上。我们通过计算ACBAR辐射热计阵列不同单元信号之间的相关性来恢复存在仪器噪声的大气信号。利用这种方法，即使在最稳定的大气条件下，也可以测量出高信噪比的大气亮度波动。观测到的大气信号由Kolmogorov-Taylor （KT）模式的参数表征，即描述观测时大气功率谱的振幅和幂律指数以及风速的两个分量。KT模型通常很好地描述了观测到的波动，并与数据拟合产生与理论预期一致的Kolmogorov指数值。将风的角速度结果与风的线速度测量结果相结合，我们发现观测到的大气波动高度与探空资料确定的水汽分布是一致的。对于以150、219和274 GHz为中心的频段对应的数据，我们得到了以瑞利-琼斯温度单位为单位的中位波动功率幅值为（10、38、74）mK2 rad-5/3。与以前的工作相比，我们发现这些中位振幅大约比南半球夏季在南极发现的中位振幅小一个数量级，比在阿塔卡马沙漠的ALMA站点发现的中位振幅至少低30倍。
We report measurements of the millimeter wavelength brightness fluctuations produced by the atmosphere above the South Pole made with the Arcminute Cosmology Bolometer Array Receiver (ACBAR). The data span the 2002 austral winter during which ACBAR was mounted on the Viper Telescope at the South Pole. We recover the atmospheric signal in the presence of instrument noise by calculating the correlation between signals from distinct elements of the ACBAR bolometer array. With this method, it is possible to measure atmospheric brightness fluctuations with a high signal-to-noise ratio even under the most stable atmospheric conditions. The observed atmospheric signal is characterized by the parameters of the Kolmogorov-Taylor (KT) model, which are the amplitude and power-law exponent describing the atmospheric power spectrum and the two components of the wind angular velocity at the time of the observation. The KT model is typically a good description of the observed fluctuations, and fits to the data produce values of the Kolmogorov exponent that are consistent with theoretical expectations. By combining the wind angular velocity results with measurements of the wind linear velocity, we find that the altitude of the observed atmospheric fluctuations is consistent with the distribution of water vapor determined from radiosonde data. For data corresponding to frequency passbands centered on 150, 219, and 274 GHz, we obtain median fluctuation power amplitudes of (10, 38, 74) mK2 rad-5/3 in Rayleigh-Jeans temperature units. Comparing with previous work, we find that these median amplitudes are approximately an order of magnitude smaller than those found at the South Pole during the austral summer and at least 30 times lower than found at the ALMA site in the Atacama desert.