Lidar backscatter and wind retrievals of the planetary boundary layer height (PBLH) are assimilated into 22-hourly forecasts from the NASA Unified – Weather and Research Forecast (NU-WRF) model during the Plains Elevated Convection at Night (PECAN) campaign on 11 July 2015 in Greensburg, Kansas, using error statistics collected from the model profiles to compute the necessary covariance matrices. Two separate forecast runs using different PBL physics schemes were employed, and comparisons with six independent radiosonde profiles were made for each run. Both of the forecast runs accurately predicted the PBLH and the state variable profiles within the planetary boundary layer during the early morning, and the assimilation had a small impact during this time. In the late afternoon, the forecast runs showed decreased accuracy as the convective boundary layer developed. However, assimilation of the Doppler lidar PBLH observations was found to improve the temperature and V-velocity profiles relative to independent radiosonde profiles. Water vapor was overcorrected, leading to increased differences with independent data. Errors in the U velocity were made slightly larger. The computed forecast error covariances between the PBLH and state variables were found to rise in the late afternoon, leading to the larger improvements in the afternoon. This work represents the first effort to assimilate PBLH into forecast states using ensemble methods.

中文翻译：

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激光雷达行星边界层高度观测的同化

在7月11日夜间夜间高对流（PECAN）活动期间，NASA统一的天气和研究预报（NU-WRF）模型将22个小时的卫星边界层高度（PBLH）的激光雷达后向散射和风向反演同化2015年在堪萨斯州格林斯堡，使用从模型配置文件中收集的误差统计信息来计算必要的协方差矩阵。使用不同的PBL物理方案进行了两次单独的预测运行，并针对每次运行与六个独立的探空仪剖面进行了比较。这两个预报运行都在清晨准确预测了PBLH和行星边界层内的状态变量剖面，并且在这段时间内，同化影响很小。在午后 随着对流边界层的发展，预报结果显示准确性降低。但是，发现多普勒激光雷达的PBLH观测值的同化可以改善温度和相对于独立探空仪剖面的V速度剖面。水蒸气被过度校正，导致独立数据的差异增加。U速度的误差稍大一些。发现PBLH和状态变量之间的预测误差协方差在下午晚些时候上升，导致下午有较大的改善。这项工作代表了使用集成方法将PBLH吸收到预测状态的第一步。