An atmospheric hydraulic jump was observed over the Alaiz mountain range and Elorz valley near Pamplona, Spain from radial velocity retrievals performed with two scanning lidars during October 5 and 6, 2018. The jump occurred on the lee side of the mountain close to its base and the jump location was observed more than 2 km further downstream of the mountain base inside the valley. Here, we simulate the two days using the multi‐scale modeling capabilities of the Weather Research and Forecasting model. We find that the model is able to reproduce the hydraulic jump in high detail matching qualitatively well the timing and main features observed by both the scanning lidars and meteorological instruments on masts deployed throughout the area. The simulation results show that the jump starts at the beginning of the evening, right after the atmospheric conditions over the top of the Alaiz mountain become stable and the flow at the mountain top experiences a transition from subcritical to supercritical. The simulations also show that the jump lasts about 10 h until it moves close to the mountain top; then lee‐wave activity dominates and lasts until late in the morning. The flow at the mountain top is only supercritical during the periods where the jump and the lee waves take place. The jump and lee‐wave regimes can be distinguished from the simulation results by analyzing the ratio of the depth‐average Brunt‐Väisälä frequency to the depth‐average mean wind speed both upstream and downstream of the mountain top.

中文翻译：

---

大气水力跳跃和山浪的激光雷达观测和数值模拟

在2018年10月5日至6日使用两个扫描激光雷达进行的径向速度反演中，在西班牙潘普洛纳附近的Alaiz山脉和Elorz谷地观察到了大气水力跃变。该跃迁发生在靠近其底部和底部的山的背风侧在山谷内山基下游2公里多处观察到跳跃位置。在这里，我们使用Weather Research and Forecasting模型的多尺度建模功能来模拟这两天。我们发现，该模型能够在细节上很好地重现水力跃变，从而在质量和时间上以及通过扫描激光雷达和气象仪器在整个区域部署的桅杆上观测到的主要特征方面都能很好地匹配主要特征。仿真结果表明，跳跃从傍晚开始，在Alaiz山顶的大气条件变得稳定之后，山顶的流量经历了从次临界到超临界的过渡。模拟还表明，跳跃持续约10小时，直到它移到山顶附近为止。然后，背风活动占主导地位，一直持续到清晨。仅在跳跃和背风发生期间，山顶的水流才是超临界的。通过分析山顶上游和下游的平均深度Brunt-Väisälä频率与深度平均平均风速之比，可以从模拟结果中区分跳跃和背风状态。模拟还表明，跳跃持续约10小时，直到它移到山顶附近为止。然后，背风活动占主导地位，一直持续到清晨。仅在跳跃和背风发生期间，山顶的水流才是超临界的。通过分析山顶上游和下游的平均深度Brunt-Väisälä频率与深度平均平均风速之比，可以从模拟结果中区分跳跃和背风状态。模拟还表明，跳跃持续约10小时，直到它移到山顶附近为止。然后，背风活动占主导地位，一直持续到清晨。仅在发生跳跃和背风的时期，山顶的水流才是超临界的。通过分析山顶上游和下游的平均深度Brunt-Väisälä频率与深度平均平均风速之比，可以从模拟结果中区分跳跃和背风状态。