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中国物理学会期刊

一种光谱特征增强驱动的机器学习地基红外高光谱云检测方法

CSTR: 32037.14.aps.74.20250982

A spectral feature enhancement-driven machine learning method for cloud detection using ground-based infrared hyperspectral data

CSTR: 32037.14.aps.74.20250982
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  • 云是地基红外高光谱仪器探测大气的重要干扰源, 有效云检测不可或缺. 水汽干扰和高云识别精度低是云检测面临的两个关键挑战. 本文利用大气红外光谱探测仪(ASSIST)在云南丽江、西藏自治区墨脱和西藏自治区日土的观测数据, 分析了晴空和有云条件下的光谱特征差异, 并据此提出了一种光谱特征增强的机器学习云检测方法. 结合同步观测的激光雷达、气象站及全天空成像仪数据, 系统评估了该方法在不同相对湿度(RH)和不同云底高度(CBH)条件下的检测性能. 实验结果表明: 该方法与激光雷达检测结果的一致性高达97.61%. 在不同RH条件下, 该方法精度均优于使用原始光谱特征的方法, 尤其在RH > 70%时, 对晴空光谱的识别精度提升明显, 从86.01%提高至91.89%. 同样, 在不同CBH条件下, 新方法也展现出优于使用原始光谱特征方法的性能, 特别在识别3 km < CBH 5 km的中云和CBH > 5 km的高云时, 精度提升尤为明显. 当3 km < CBH 5 km时, 精度从95.45%提升至98.64%; 当CBH > 5 km时, 精度从87.5%提升至91.67%.

     

    Clouds exert a significant influence on infrared radiation, making cloud detection a crucial step in the application of infrared hyperspectral data. In particular, water vapor interference and the limited accuracy in high-cloud identification constitute two key challenges for ground-based infrared hyperspectral cloud detection. Traditional threshold-based cloud detection methods are difficult to adapt to different locations and dynamically changing atmospheric conditions,while machine learning methods can achieve cloud detection with higher accuracy, greater robustness, and improved automation. Building on the advantages of machine learning, observational data from the atmospheric sounder spectrometer by infrared spectral technology (ASSIST), collected at Lijiang (Yunnan), Motuo (Xizang Autonomous Region), and Ritu (Xizang Autonomous Region) in China, are used to analyze the spectral differences between sunny and cloudy conditions in this study. Based on these differences, a spectral feature enhancement-driven machine learning method for cloud detection is proposed. Finally, by incorporating synchronous observations from lidar, meteorological stations, and all-sky imagers, the proposed method is systematically evaluated under different relative humidity (RH) and cloud base height (CBH) conditions. The experimental results show that the consistency between the results obtained by the proposed method and lidar-based detection is as high as 97.61%. Under different RH conditions, the proposed method outperforms the method based on original spectral features. Notably, when \textRH > 70\text% , the accuracy of clear-sky spectral identification improves significantly: increasing from 86.01% to 91.89%. Similarly, under different CBH conditions, the proposed method also exhibits superior performance compared with the method in which original spectral features are used. In particular, the accuracy improvements are especially notable when identifying mid-level clouds with \text3 km < \textCBH \leqslant 5\text km, as well as high-level clouds with \textCBH > 5\text km. When \text3 km < \textCBH \leqslant 5\text km, the accuracy increases from 95.45% to 98.64% and when \textCBH > 5\text km, the accuracy improves from 87.5% to 91.67%. The proposed method significantly enhances the automation and accuracy of cloud detection, thereby providing higher-quality fundamental datasets for supporting subsequent applications such as radiative transfer simulation, remote sensing parameter retrieval, and data assimilation in numerical weather prediction (NWP) models.

     

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