the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Mar 2024
Study on the influence of topography on wind shear-numerical simulation based on WRF-CALMET
Abstract. This study focuses on the critical issue of low-altitude wind shear, vital for aircraft safety during takeoff and landing. Using the WRF-CALMET model, we assess the impact of topography on low-level wind shear at Zhongchuan Airport. CALMET outperforms WRF, showing improved simulation accuracy. CALMET's simulation highlights diurnal variations in vertical wind shear, especially pronounced from 13:00 to 24:00. Notably, CALMET indicates 1–2 hazard levels higher wind shear for aircraft operations compared to WRF in a significant area. Terrain sensitivity experiments reveal CALMET's responsiveness to terrain changes during high wind shear periods, with reduced impact at higher altitudes. CALMET's incorporation of kinematic terrain influences, blocking effects, slope flow, and strengthened diversion of near-surface airflow on complex terrain contribute to these findings. This study confirms the efficacy of CALMET in simulating low-altitude wind shear, emphasizing its superiority in capturing terrain influences and reducing the aviation safety threat posed by low-altitude wind shear.
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RC1: 'Comment on egusphere-2024-609', Anonymous Referee #1, 06 Apr 2024
There are a couple of major limitations with the present study. One is the number of cases. Just one particular case is considered. Is it representative of windshear at that airport? Second is that the verification of the models is made with a times series of measured wind speed only. There are many discussions of vertical windshear in the manuscript. But they look like conjectures, and not substantiated by actual observations. Are there vertical wind profiles from radar wind profilers or Doppler LIDARs? Are there flight data from aircraft?
Moreover, the background of the windshear event is not discussed in detail. What is the synoptic and mesoscale patterns? Why there is windshear for the case? What is the nature of the windshear?
Also, CALMET as a dynamic downscaling tool is a bit out-dated. We can use numerical simulations by numerical weather prediction models at sub-kilometre skill or even sub-100 m scale for simulations. Of course they may be considered to be future studies, the limitations of CALMET model at least have to be spelt out.
Please provide a comprehensive review of terrain-induced windshear at other airports, and what observations and forecasting tools are used at these airports. With that as the background, discuss the novelty and scientific contributions of this manuscript.
Citation: https://doi.org/10.5194/egusphere-2024-609-RC1 -
AC1: 'Reply on RC1', Xingyu Wang, 09 Apr 2024
Thank you very much for your questions and suggestions regarding our research.
1.One is the number of cases. Just one particular case is considered. Is it representative of windshear at that airport?Response:we chose a particular case to study the impact of airport terrain on wind shear. However, this specific case does not necessarily represent the overall wind shear situation at the airport, as it is just one weather event with significant wind shear. Due to limitations in article length, we focused on studying this particular case in detail. We appreciate your suggestion, and we will address this limitation in the conclusions section.
2.Second is that the verification of the models is made with a times series of measured wind speed only.There are many discussions of vertical windshear in the manuscript.But they look like conjectures, and not substantiated by actual observations.Are there vertical wind profiles from radar wind profilers or Doppler LIDARs?Are there flight data from aircraft?
Response:Obtaining radar wind profiler data for the airport poses certain difficulties, and we do not have Doppler lidar equipment available. Direct observation of wind shear is challenging. We have made efforts to obtain reanalysis data and site wind speed observations as much as possible. Due to limited funding in the preliminary stages of our research, we could only start with theoretical studies, and field experiments will be conducted once funding becomes available. We appreciate your suggestion, and we will acknowledge this limitation in the conclusions.
3.The background of the windshear event is not discussed in detail. What is the synoptic and mesoscale patterns? Why there is windshear for the case? What is the nature of the windshear?
Response:we have discussed the background of the wind shear event in the supplement. The results indicate that during this period, a two-trough-two-ridge system in the East Asia region shifted eastward. This led to a deepening of the low-pressure trough at the location of the airport, with a significant strengthening of cold advection behind the ridge. Momentum descended from the upper atmosphere, and analysis of convective instability energy indicates significant convective activity in the airport area during this event. Therefore, this wind shear event was induced by terrain during convective weather in summer (Zhao, 2021).
4.CALMET as a dynamic downscaling tool is a bit out-dated. We can use numerical simulations by numerical weather prediction models at sub-kilometre skill or even sub-100 m scale for simulations. Of course they may be considered to be future studies, the limitations of CALMET model at least have to be spelt out.
回应：当然，更高分辨率的建模建模是模型研究的一个趋势。WRF可以模拟低至亚百米分辨率的比例。从操作角度来看，CALMET模型仅模拟风场，计算需求和硬件要求低于WRF模型，用于相同规模的模拟。我们认为CALMET模型在实际应用中具有研究价值。感谢您的建议，我们将在结论中解决CALMET的局限性。
5.请全面回顾其他机场的地形风切变，以及这些机场使用了哪些观测和预报工具。以此为背景，讨论这份手稿的新颖性和科学贡献。
回应：谢谢你的建议。我们在预印本的介绍中提到了两个使用WRF和WRF-LES在香港国际机场的地形诱发风切变的案例。然而，我们承认这可能还不够，我们将包括更多的背景研究来讨论手稿的新颖性和科学贡献。此外，我们计划在未来的研究中应用这种方法来研究不同机场的低层风切变。
Citation: https://doi.org/10.5194/egusphere-2024-609-AC1 -
RC2: 'Reply on AC1', Anonymous Referee #1, 09 Apr 2024
There are Chinese characters. Please change them to English.
Citation: https://doi.org/10.5194/egusphere-2024-609-RC2 -
AC2: 'Reply on RC2', Xingyu Wang, 10 Apr 2024
Thank you very much for your questions and suggestions regarding our research.
1.One is the number of cases. Just one particular case is considered. Is it representative of windshear at that airport?Response:we chose a particular case to study the impact of airport terrain on wind shear. However, this specific case does not necessarily represent the overall wind shear situation at the airport, as it is just one weather event with significant wind shear. Due to limitations in article length, we focused on studying this particular case in detail. We appreciate your suggestion, and we will address this limitation in the conclusions section.
2.Second is that the verification of the models is made with a times series of measured wind speed only.There are many discussions of vertical windshear in the manuscript.But they look like conjectures, and not substantiated by actual observations.Are there vertical wind profiles from radar wind profilers or Doppler LIDARs?Are there flight data from aircraft?
Response:Obtaining radar wind profiler data for the airport poses certain difficulties, and we do not have Doppler lidar equipment available. Direct observation of wind shear is challenging. We have made efforts to obtain reanalysis data and site wind speed observations as much as possible. Due to limited funding in the preliminary stages of our research, we could only start with theoretical studies, and field experiments will be conducted once funding becomes available. We appreciate your suggestion, and we will acknowledge this limitation in the conclusions.
3.The background of the windshear event is not discussed in detail. What is the synoptic and mesoscale patterns? Why there is windshear for the case? What is the nature of the windshear?
Response:we have discussed the background of the wind shear event in the supplement. The results indicate that during this period, a two-trough-two-ridge system in the East Asia region shifted eastward. This led to a deepening of the low-pressure trough at the location of the airport, with a significant strengthening of cold advection behind the ridge. Momentum descended from the upper atmosphere, and analysis of convective instability energy indicates significant convective activity in the airport area during this event. Therefore, this wind shear event was induced by terrain during convective weather in summer (Zhao, 2021).
4.CALMET as a dynamic downscaling tool is a bit out-dated. We can use numerical simulations by numerical weather prediction models at sub-kilometre skill or even sub-100 m scale for simulations. Of course they may be considered to be future studies, the limitations of CALMET model at least have to be spelt out.
Response: Sure, higher-resolution modeling modeling is a trend in model research. WRF can simulate scales down to sub-hundred-meter resolutions. From an operational perspective, the CALMET model only simulates wind fields, with computational demands and hardware requirements lower than the WRF model for simulations at the same scale. We believe that the CALMET model has research value in practical applications. Thank you for your suggestion, and we will address the limitations of CALMET in the conclusions.
5.Please provide a comprehensive review of terrain-induced windshear at other airports, and what observations and forecasting tools are used at these airports. With that as the background, discuss the novelty and scientific contributions of this manuscript.
Response: Thank you for your suggestion. We mentioned two cases of terrain-induced wind shear at Hong Kong International Airport using WRF and WRF-LES in the introduction of the preprint. However, we acknowledge that this may not be sufficient, and we will include more background research to discuss the novelty and scientific contributions of the manuscript. Additionally, we plan to apply this method to study low-level wind shear at different airports in future research.
Citation: https://doi.org/10.5194/egusphere-2024-609-AC2
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AC2: 'Reply on RC2', Xingyu Wang, 10 Apr 2024
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RC2: 'Reply on AC1', Anonymous Referee #1, 09 Apr 2024
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AC1: 'Reply on RC1', Xingyu Wang, 09 Apr 2024
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RC3: 'Comment on egusphere-2024-609', Xiaohang Wen, 15 Apr 2024
- Line 258, "4.2 Impact of Topography on Wind Shear Simulation" should be "3.2 Impact of Topography on Wind Shear Simulation".
- Line 315 and 317, for "with a peak of 3.27m/s/10m ..." and "with CALMET_RAISE reaching an exceptional maximum of 12.62m/s/10m ...", are the units of vertical wind shear incorrect?
- Line 329, do the x-axis and y-axis of Figure 6 consistent with the x-axis and y-axis of Figure 5? Are latitude and longitude used rather than 0, 50, 150, etc.?
Citation: https://doi.org/10.5194/egusphere-2024-609-RC3 -
AC3: 'Reply on RC3', Xingyu Wang, 16 Apr 2024
Thank you very much for correcting the errors in my article and providing valuable feedback. I will promptly rectify issues 1 and 3.
Regarding issue 2, you raised a question about the unit of vertical wind shear. Typically, the unit of vertical wind shear is expressed in m/s. However, in my article, I opted to use m/s/10m to represent the wind shear magnitude between two 10-meter height layers. This unit signifies the rate of change of wind speed per 10 meters of vertical height. Such representation is common in meteorology and wind energy research, aiding in a better understanding of wind speed variations in the vertical direction, especially in contexts involving terrain and complex environmental influences.
Citation: https://doi.org/10.5194/egusphere-2024-609-AC3
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