Jinhua Zhong

The planetary boundary layer (PBL) height determines the vertical scale of transport and mixing, making it a critical parameter in air pollution studies, weather forecasting, climate modelling, and many other applications. However, the accuracy of boundary layer height (BLH) representation by models in complex terrain conditions still requires further in-depth research. To address this critical scientific issue, the present study investigates the BLH from various simultaneous observations of multi-remote sensing instruments radiosonde (RS), wind profiler radar (WPR), and microwave radiometer (MWR) and six PBL parameterization schemes (Asymmetrical Convective Model version 2 (ACM2), Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Mellor-Yamada-Nakanishi-Niino Level 2.5 (MYNN2), Mellor-Yamada-Nakanishi-Niino 3 (MYNN3) and Bougeault-Lacarrère (BouLac)) within the Weather Research and Forecasting (WRF) model from the Liangshan Prefecture (LSP) region during complex mountainous conditions. The findings are as follows: (1) The continuous wavelet transform (CWT) method is suitable for retrieving daytime convective boundary layer height (CBLH) in complex terrain, although aerosol layers interfere with the retrievals, and results from traditional threshold methods using MWR closely simulate the diurnal variation of BLH in the LSP. (2) WRF model simulates potential temperature and mixing ratio (𝜃 and R) profiles well, but shows discrepancies in wind speed simulation, particularly in capturing the weak near-surface inversion layer, leading to biases in BLH estimation. (3) Among the various PBL schemes, ACM2 and MYNN3 perform best in simulating BLH, with ACM2 recommended for convective conditions and MYNN3 for stable boundary layers, while YSU and MYJ consistently underestimate BLH. (4) The daytime atmosphere in mountainous regions typically exhibits a multi-layered structure, with mountain-induced exchange processes transporting high-suspended aerosol layers, causing discrepancies between thermodynamic-determined CBLH and actual BLH. In valleys and urban areas where BLH is higher than in the surrounding mountains.

The planetary boundary layer (PBL) height determines the vertical scale of transport and mixing, making it a critical parameter in air pollution studies, weather forecasting, climate modelling, and many other applications. However, the accuracy of boundary layer height (BLH) representation by models in complex terrain conditions still requires further in-depth research. To address this critical scientific issue, the present study investigates the BLH from various simultaneous observations of multi-remote sensing instruments radiosonde (RS), wind profiler radar (WPR), and microwave radiometer (MWR) and six PBL parameterization schemes (Asymmetrical Convective Model version 2 (ACM2), Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Mellor-Yamada-Nakanishi-Niino Level 2.5 (MYNN2), Mellor-Yamada-Nakanishi-Niino 3 (MYNN3) and Bougeault-Lacarrère (BouLac)) within the Weather Research and Forecasting (WRF) model from the Liangshan Prefecture (LSP) region during complex mountainous conditions. The findings are as follows: (1) The continuous wavelet transform (CWT) method is suitable for retrieving daytime convective boundary layer height (CBLH) in complex terrain, although aerosol layers interfere with the retrievals, and results from traditional threshold methods using MWR closely simulate the diurnal variation of BLH in the LSP. (2) WRF model simulates potential temperature and mixing ratio (𝜃 and R) profiles well, but shows discrepancies in wind speed simulation, particularly in capturing the weak near-surface inversion layer, leading to biases in BLH estimation. (3) Among the various PBL schemes, ACM2 and MYNN3 perform best in simulating BLH, with ACM2 recommended for convective conditions and MYNN3 for stable boundary layers, while YSU and MYJ consistently underestimate BLH. (4) The daytime atmosphere in mountainous regions typically exhibits a multi-layered structure, with mountain-induced exchange processes transporting high-suspended aerosol layers, causing discrepancies between thermodynamic-determined CBLH and actual BLH. In valleys and urban areas where BLH is higher than in the surrounding mountains.

The planetary boundary layer (PBL) height determines the vertical scale of transport and mixing, making it a critical parameter in air pollution studies, weather forecasting, climate modelling, and many other applications. However, the accuracy of boundary layer height (BLH) representation by models in complex terrain conditions still requires further in-depth research. To address this critical scientific issue, the present study investigates the BLH from various simultaneous observations of multi-remote sensing instruments radiosonde (RS), wind profiler radar (WPR), and microwave radiometer (MWR) and six PBL parameterization schemes (Asymmetrical Convective Model version 2 (ACM2), Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Mellor-Yamada-Nakanishi-Niino Level 2.5 (MYNN2), Mellor-Yamada-Nakanishi-Niino 3 (MYNN3) and Bougeault-Lacarrère (BouLac)) within the Weather Research and Forecasting (WRF) model from the Liangshan Prefecture (LSP) region during complex mountainous conditions. The findings are as follows: (1) The continuous wavelet transform (CWT) method is suitable for retrieving daytime convective boundary layer height (CBLH) in complex terrain, although aerosol layers interfere with the retrievals, and results from traditional threshold methods using MWR closely simulate the diurnal variation of BLH in the LSP. (2) WRF model simulates potential temperature and mixing ratio (𝜃 and R) profiles well, but shows discrepancies in wind speed simulation, particularly in capturing the weak near-surface inversion layer, leading to biases in BLH estimation. (3) Among the various PBL schemes, ACM2 and MYNN3 perform best in simulating BLH, with ACM2 recommended for convective conditions and MYNN3 for stable boundary layers, while YSU and MYJ consistently underestimate BLH. (4) The daytime atmosphere in mountainous regions typically exhibits a multi-layered structure, with mountain-induced exchange processes transporting high-suspended aerosol layers, causing discrepancies between thermodynamic-determined CBLH and actual BLH. In valleys and urban areas where BLH is higher than in the surrounding mountains.

The planetary boundary layer (PBL) height determines the vertical scale of transport and mixing, making it a critical parameter in air pollution studies, weather forecasting, climate modelling, and many other applications. However, the accuracy of boundary layer height (BLH) representation by models in complex terrain conditions still requires further in-depth research. To address this critical scientific issue, the present study investigates the BLH from various simultaneous observations of multi-remote sensing instruments radiosonde (RS), wind profiler radar (WPR), and microwave radiometer (MWR) and six PBL parameterization schemes (Asymmetrical Convective Model version 2 (ACM2), Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Mellor-Yamada-Nakanishi-Niino Level 2.5 (MYNN2), Mellor-Yamada-Nakanishi-Niino 3 (MYNN3) and Bougeault-Lacarrère (BouLac)) within the Weather Research and Forecasting (WRF) model from the Liangshan Prefecture (LSP) region during complex mountainous conditions. The findings are as follows: (1) The continuous wavelet transform (CWT) method is suitable for retrieving daytime convective boundary layer height (CBLH) in complex terrain, although aerosol layers interfere with the retrievals, and results from traditional threshold methods using MWR closely simulate the diurnal variation of BLH in the LSP. (2) WRF model simulates potential temperature and mixing ratio (𝜃 and R) profiles well, but shows discrepancies in wind speed simulation, particularly in capturing the weak near-surface inversion layer, leading to biases in BLH estimation. (3) Among the various PBL schemes, ACM2 and MYNN3 perform best in simulating BLH, with ACM2 recommended for convective conditions and MYNN3 for stable boundary layers, while YSU and MYJ consistently underestimate BLH. (4) The daytime atmosphere in mountainous regions typically exhibits a multi-layered structure, with mountain-induced exchange processes transporting high-suspended aerosol layers, causing discrepancies between thermodynamic-determined CBLH and actual BLH. In valleys and urban areas where BLH is higher than in the surrounding mountains.

The planetary boundary layer (PBL) height determines the vertical scale of transport and mixing, making it a critical parameter in air pollution studies, weather forecasting, climate modelling, and many other applications. However, the accuracy of boundary layer height (BLH) representation by models in complex terrain conditions still requires further in-depth research. To address this critical scientific issue, the present study investigates the BLH from various simultaneous observations of multi-remote sensing instruments radiosonde (RS), wind profiler radar (WPR), and microwave radiometer (MWR) and six PBL parameterization schemes (Asymmetrical Convective Model version 2 (ACM2), Yonsei University (YSU), Mellor-Yamada-Janjic (MYJ), Mellor-Yamada-Nakanishi-Niino Level 2.5 (MYNN2), Mellor-Yamada-Nakanishi-Niino 3 (MYNN3) and Bougeault-Lacarrère (BouLac)) within the Weather Research and Forecasting (WRF) model from the Liangshan Prefecture (LSP) region during complex mountainous conditions. The findings are as follows: (1) The continuous wavelet transform (CWT) method is suitable for retrieving daytime convective boundary layer height (CBLH) in complex terrain, although aerosol layers interfere with the retrievals, and results from traditional threshold methods using MWR closely simulate the diurnal variation of BLH in the LSP. (2) WRF model simulates potential temperature and mixing ratio (𝜃 and R) profiles well, but shows discrepancies in wind speed simulation, particularly in capturing the weak near-surface inversion layer, leading to biases in BLH estimation. (3) Among the various PBL schemes, ACM2 and MYNN3 perform best in simulating BLH, with ACM2 recommended for convective conditions and MYNN3 for stable boundary layers, while YSU and MYJ consistently underestimate BLH. (4) The daytime atmosphere in mountainous regions typically exhibits a multi-layered structure, with mountain-induced exchange processes transporting high-suspended aerosol layers, causing discrepancies between thermodynamic-determined CBLH and actual BLH. In valleys and urban areas where BLH is higher than in the surrounding mountains.

Quantitative precipitation forecast (QPF) verification stands out as one of the most formidable endeavors in the realm of forecast verification. Traditional verification methods are not suitable for high-resolution forecasting products in some cases. Therefore, the SAL (structure, amplitude and location) method was proposed as a method of object-based spatial verification that studies precipitation verification in a certain range, which is combined with factors including structure, amplitude and location of the targets. However, the setting of the precipitation threshold would affect the result of the verification. This paper presented an improved method for determining the precipitation threshold using the QPF from ECMWF, which is an ensemble forecast model and three-source fusion product that was used in China from 1 July to 31 August 2020, and then the results obtained with this method were compared with the other two traditional methods. Furthermore, the SAL and the traditional verification methods were carried out for geometric, simulated and real cases, respectively. The results showed the following: (1) The proposed method in this paper for determining the threshold was more accurate at identifying the precipitation objects. (2) The verification area size was critical for SAL calculation. If the area selected was too large, the calculated SAL value had little significance. (3) ME (Mean Error) could not identify the displacement between prediction and observation, while HSS (Heidke Skill Score) was sensitive to the displacement of the prediction field. (4) Compared with the traditional verification methods, the SAL method was more straight forward and simple, and it could give a better representation of prediction ability. Therefore, forecasters can better understand the model prediction effect and what needs to be improved.