Extending water vapor measurement capability of photon-limited differential absorption lidars through simultaneous denoising and inversion
Extending water vapor measurement capability of photon-limited differential absorption lidars through simultaneous denoising and inversion
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DOI：
10.5194/amt-15-5159-2022
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发表时间：
2022-09
影响因子：
3.8
通讯作者：
Willem J. Marais;M. Hayman
中科院分区：
文献类型：
--
作者：
Willem J. Marais;M. Hayman
抽象的。微脉冲差分吸收激光雷达（MPD）是由蒙大拿州立大学（MSU）和国家大气研究中心（NCAR）开发的，用于使用低功率激光和光子计数探测器进行距离分辨水汽（WV）测量。MPD已被证明可以在高达6公里的高度上进行精确的WV测量。然而，MPD的能力，以产生准确的更高的高度WV测量是目前的标准差分吸收激光雷达（DIAL）检索方法的阻碍。这些方法是建立在一个基本的方法，代数求解的WV使用的MPD前向模型和噪声观测，加剧了任何随机噪声的激光雷达观测。本文介绍了适用于MPD仪器的自适应泊松全变差（PTV）。PTV最初是为地基高光谱分辨率激光雷达开发的，本文报道了为了将PTV应用于MPD WV观测所需的适应性。适应PTV的方法，创造PTV-MPD，扩展MPD的最大高度从6公里到8公里，并大大提高了WV检索的精度从2公里以上。PTV-MPD通过同时对MPD噪声观测进行去噪并通过将随机噪声与非随机WV分离来推断WV来实现改进。对130个无线电探空仪（RS）资料的对比分析表明，在6 ~ 8 km范围内，RS与PTV-MPD的相对均方根误差（RRMSE）超过100%，而在3 km范围内，RS与标准方法的相对均方根误差（RRMSE）超过100%。此外，我们表明，通过采用PTV-MPD，MPD是能够扩展其有用的范围以外的WV估计的ARM南部大平原拉曼激光雷达（RRMSE超过100%之间3和4公里），拉曼激光雷达的功率孔径产品大于500倍的MPD。
Abstract. The micropulse differential absorption lidar (MPD) was developed at Montana State University (MSU) and the National Center for Atmospheric Research (NCAR) to perform range-resolved water vapor (WV) measurements using low-power lasers and photon-counting detectors. The MPD has proven to produce accurate WV measurements up to 6 km altitude. However, the MPD's ability to produce accurate higher-altitude WV measurements is impeded by the current standard differential absorption lidar (DIAL) retrieval methods. These methods are built upon a fundamental methodology that algebraically solves for the WV using the MPD forward models and noisy observations, which exacerbates any random noise in the lidar observations. The work in this paper introduces the adapted Poisson total variation (PTV) specifically for the MPD instrument. PTV was originally developed for a ground-based high spectral resolution lidar, and this paper reports on the adaptations that were required in order to apply PTV on MPD WV observations. The adapted PTV method, coined PTV-MPD, extends the maximum altitude of the MPD from 6 to 8 km and substantially increases the accuracy of the WV retrievals starting above 2 km. PTV-MPD achieves the improvement by simultaneously denoising the MPD noisy observations and inferring the WV by separating the random noise from the non-random WV. An analysis with 130 radiosonde (RS) comparisons shows that the relative root-mean-square difference (RRMSE) of WV measurements between RS and PTV-MPD exceeds 100 % between 6 and 8 km, whereas the RRMSE between RS and the standard method exceeds 100 % near 3 km. In addition, we show that by employing PTV-MPD, the MPD is able to extend its useful range of WV estimates beyond that of the ARM Southern Great Plains Raman lidar (RRMSE exceeding 100 % between 3 and 4 km); the Raman lidar has a power-aperture product 500 times greater than that of the MPD.