Cold surges can significantly affect maritime transportation safety, owing to the strong wind, significant temperature drop, as well as dense fog. Therefore, it is crucial to make an accurate prediction of meteorological phenomenon in the maritime regions during cold surges. The present study evaluates the performance of planetary boundary layer (PBL) and land surface schemes in Weather Research and Forecasting (WRF) model, specifically for the wind (wind speed and direction) and fog (temperature, dew point temperature, and relative humidity), during two cold surge events that occurred in November 2022, in the Bohai Bay Area, China. To make a thorough investigation of those complex meteorological processes, the WRF model was configured over Bohai Bay with a high spatial resolution of 2 km in the horizontal direction, and results were verified using three accessible meteorological stations around the Shandong Peninsula. Our studies demonstrate that the WRF tends to perform better in strong winds than in weak ones, particularly in the simulation of wind direction. Besides, Mellor–Yamada Nakanishi Niino Level 2.5 (MYNN2.5) and Yonsei University Scheme (YSU) PBL schemes demonstrate superior performance in simulating wind speed and sea fog, respectively, compared with the Noah-MP scheme. Unified Noah demonstrates superior performance in dew point temperature and humidity compared with both Noah-MP and 5-layer thermal diffusion schemes, whereas Noah-MP excels in temperature performance. Finally, we utilize the optimal results produced by the WRF model and integrate them with the risk thresholds for ship navigation. This allows us to visualize the spatiotemporal distribution of risks associated with strong winds and fog during navigation in the Bohai Bay area. The abovementioned findings are supposed to be helpful for make more accurate weather forecast of strong wind and dense fog in future cold surge events, from the viewpoint of a safe maritime transportation.
{"title":"Study on the forecasting of two cold surge events from the viewpoint of maritime transport","authors":"Chen Chen, Haoyu Chen, Kenji Sasa","doi":"10.1002/met.70029","DOIUrl":"https://doi.org/10.1002/met.70029","url":null,"abstract":"<p>Cold surges can significantly affect maritime transportation safety, owing to the strong wind, significant temperature drop, as well as dense fog. Therefore, it is crucial to make an accurate prediction of meteorological phenomenon in the maritime regions during cold surges. The present study evaluates the performance of planetary boundary layer (PBL) and land surface schemes in Weather Research and Forecasting (WRF) model, specifically for the wind (wind speed and direction) and fog (temperature, dew point temperature, and relative humidity), during two cold surge events that occurred in November 2022, in the Bohai Bay Area, China. To make a thorough investigation of those complex meteorological processes, the WRF model was configured over Bohai Bay with a high spatial resolution of 2 km in the horizontal direction, and results were verified using three accessible meteorological stations around the Shandong Peninsula. Our studies demonstrate that the WRF tends to perform better in strong winds than in weak ones, particularly in the simulation of wind direction. Besides, Mellor–Yamada Nakanishi Niino Level 2.5 (MYNN2.5) and Yonsei University Scheme (YSU) PBL schemes demonstrate superior performance in simulating wind speed and sea fog, respectively, compared with the Noah-MP scheme. Unified Noah demonstrates superior performance in dew point temperature and humidity compared with both Noah-MP and 5-layer thermal diffusion schemes, whereas Noah-MP excels in temperature performance. Finally, we utilize the optimal results produced by the WRF model and integrate them with the risk thresholds for ship navigation. This allows us to visualize the spatiotemporal distribution of risks associated with strong winds and fog during navigation in the Bohai Bay area. The abovementioned findings are supposed to be helpful for make more accurate weather forecast of strong wind and dense fog in future cold surge events, from the viewpoint of a safe maritime transportation.</p>","PeriodicalId":49825,"journal":{"name":"Meteorological Applications","volume":"32 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/met.70029","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aircraft observations derived from Mode-Select Enhanced Surveillance (Mode-S EHS) reports are a valuable, high temporo-spatial resolution, source of upper-air information that can be assimilated into numerical weather prediction models. At present temperature and wind Mode-S EHS observations are assimilated into the Met Office's convection-permitting model, the UKV. These observations are obtained from two different sources, an inhouse set of receivers and via the European Meteorological Aircraft Derived Data Centre (EMADDC). Currently, Mode-S EHS data are assimilated using the same observation error standard deviation profiles as AMDAR data; however, differing observation processing is anticipated to result in differing error profiles for the Met Office and EMADDC data and for the AMDAR data. Therefore, we estimate new observation error statistics, including error correlations for the two types of Mode-S EHS data. We also consider the impact of the different aircraft data on the UKV analysis. We find that the observation error standard deviation profiles for wind and temperature are dependent on observation type and season and differ from the current profiles used in the assimilation. Additionally, the Mode-S EHS observation errors have a considerable spatial correlation that increases with height and is much longer than the spatial thinning distance. The estimated observation influence shows that Mode-S EHS data are not optimally assimilated, and that the use of updated, observation-type specific, error profiles is expected to improve the assimilation. The assimilation may be further optimized by modifying the observation thinning distance or including the correlated observation errors in the assimilation.
{"title":"Observation uncertainty and impact of Mode-S aircraft observations in the Met Office limited area numerical weather prediction system","authors":"Taejun Song, Joanne A. Waller, David Simonin","doi":"10.1002/met.70036","DOIUrl":"https://doi.org/10.1002/met.70036","url":null,"abstract":"<p>Aircraft observations derived from Mode-Select Enhanced Surveillance (Mode-S EHS) reports are a valuable, high temporo-spatial resolution, source of upper-air information that can be assimilated into numerical weather prediction models. At present temperature and wind Mode-S EHS observations are assimilated into the Met Office's convection-permitting model, the UKV. These observations are obtained from two different sources, an inhouse set of receivers and via the European Meteorological Aircraft Derived Data Centre (EMADDC). Currently, Mode-S EHS data are assimilated using the same observation error standard deviation profiles as AMDAR data; however, differing observation processing is anticipated to result in differing error profiles for the Met Office and EMADDC data and for the AMDAR data. Therefore, we estimate new observation error statistics, including error correlations for the two types of Mode-S EHS data. We also consider the impact of the different aircraft data on the UKV analysis. We find that the observation error standard deviation profiles for wind and temperature are dependent on observation type and season and differ from the current profiles used in the assimilation. Additionally, the Mode-S EHS observation errors have a considerable spatial correlation that increases with height and is much longer than the spatial thinning distance. The estimated observation influence shows that Mode-S EHS data are not optimally assimilated, and that the use of updated, observation-type specific, error profiles is expected to improve the assimilation. The assimilation may be further optimized by modifying the observation thinning distance or including the correlated observation errors in the assimilation.</p>","PeriodicalId":49825,"journal":{"name":"Meteorological Applications","volume":"32 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/met.70036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the relationship between seasonal precipitation over Iran and low-level moisture, in terms of vertically integrated specific humidity (VISH) from the surface to 850 hPa. The VISH is calculated from ERA5 data for the domain (10°N–60°N, 15°E–80°E), and the precipitation is calculated from 50 stations across Iran, both for the period 1968–2023. Canonical correlation analysis (CCA) is applied to examine the spatial–temporal relationship between seasonal averages of moisture and precipitation during January–March (JFM), April–Jun (AMJ), and October–December (OND). VISH and precipitation are considered as the simultaneous predictor and predictand fields in the CCA, respectively. The CCA time series are correlated to global sea surface temperatures to assess the connections to large-scale, potentially predictable modes of variability. The CCA spatial patterns indicate that there is a strong relationship between low-level moisture and seasonal precipitation, with VISH over the Persian Gulf, Oman Sea, Arabian Sea, and Red Sea positively correlated with precipitation over most areas of Iran, while VISH over the Caspian Sea and Black is negatively correlated. Generally, these relationships are notably low over northwestern areas of Iran and the coastal regions of the Caspian Sea and the prediction skill of CCA remains limited over these regions. In OND, the leading CCA time series exhibits the well-known connection to the El Niño–Southern Oscillation (ENSO). However, the highest CCA skill is found for JFM precipitation, which does not exhibit an ENSO connection, and so may present an additional source of skill.
{"title":"The relationship between moisture in the low level of the troposphere and seasonal precipitation over Iran","authors":"Hasan Nuroozi, Amin Shirvani, Mathew Barlow","doi":"10.1002/met.70033","DOIUrl":"https://doi.org/10.1002/met.70033","url":null,"abstract":"<p>This paper investigates the relationship between seasonal precipitation over Iran and low-level moisture, in terms of vertically integrated specific humidity (VISH) from the surface to 850 hPa. The VISH is calculated from ERA5 data for the domain (10°N–60°N, 15°E–80°E), and the precipitation is calculated from 50 stations across Iran, both for the period 1968–2023. Canonical correlation analysis (CCA) is applied to examine the spatial–temporal relationship between seasonal averages of moisture and precipitation during January–March (JFM), April–Jun (AMJ), and October–December (OND). VISH and precipitation are considered as the simultaneous predictor and predictand fields in the CCA, respectively. The CCA time series are correlated to global sea surface temperatures to assess the connections to large-scale, potentially predictable modes of variability. The CCA spatial patterns indicate that there is a strong relationship between low-level moisture and seasonal precipitation, with VISH over the Persian Gulf, Oman Sea, Arabian Sea, and Red Sea positively correlated with precipitation over most areas of Iran, while VISH over the Caspian Sea and Black is negatively correlated. Generally, these relationships are notably low over northwestern areas of Iran and the coastal regions of the Caspian Sea and the prediction skill of CCA remains limited over these regions. In OND, the leading CCA time series exhibits the well-known connection to the El Niño–Southern Oscillation (ENSO). However, the highest CCA skill is found for JFM precipitation, which does not exhibit an ENSO connection, and so may present an additional source of skill.</p>","PeriodicalId":49825,"journal":{"name":"Meteorological Applications","volume":"32 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/met.70033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143497267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bayesian model averaging (BMA) and ensemble model output statistics (EMOS), as two state-of-the-art approaches, were applied to improve the prediction skills of 24-h accumulated precipitation over East Asia with lead days of 1–7 days. The multimodel ensemble precipitation probabilistic forecast experiments were constructed using ensemble forecasts from multiple ensemble prediction systems, revealing that the standard BMA (s-BMA) and the standard EMOS (s-EMOS) outperformed the raw ensemble forecasts. In comparison with the raw ensembles, the improvement by the s-BMA model increases as lead days increase, while the s-EMOS model consistently enhances prediction accuracy by around 30% for all lead days. Overall, the s-EMOS model demonstrates superior performance compared with the s-BMA model, which struggles with forecasting heavy daily precipitation exceeding 25 mm. Accordingly, the hierarchical BMA (h-BMA) model is introduced in this study, designed for different precipitation classifications. Compared with the s-BMA model, the h-BMA model notably improves the probabilistic forecast skill for all precipitation thresholds throughout East Asia, particularly for heavy precipitation events. Moreover, the h-BMA model also improves the forecast reliability across various precipitation thresholds. A hierarchical EMOS (h-EMOS) model is also developed to validate the benefits of the precipitation classifications and further improves the forecast accuracy as expected. The prediction probability density functions of the hierarchical models are much sharper and more concentrated than those of the standard models. In general, the improvement in precipitation probabilistic forecast skill of the h-BMA model relative to the s-BMA model surpasses that of the h-EMOS model compared with the s-EMOS model.
{"title":"Hierarchical multimodel ensemble probabilistic forecasts for precipitation over East Asia","authors":"Luying Ji, Xiefei Zhi, Qixiang Luo, Yan Ji","doi":"10.1002/met.70035","DOIUrl":"https://doi.org/10.1002/met.70035","url":null,"abstract":"<p>Bayesian model averaging (BMA) and ensemble model output statistics (EMOS), as two state-of-the-art approaches, were applied to improve the prediction skills of 24-h accumulated precipitation over East Asia with lead days of 1–7 days. The multimodel ensemble precipitation probabilistic forecast experiments were constructed using ensemble forecasts from multiple ensemble prediction systems, revealing that the standard BMA (s-BMA) and the standard EMOS (s-EMOS) outperformed the raw ensemble forecasts. In comparison with the raw ensembles, the improvement by the s-BMA model increases as lead days increase, while the s-EMOS model consistently enhances prediction accuracy by around 30% for all lead days. Overall, the s-EMOS model demonstrates superior performance compared with the s-BMA model, which struggles with forecasting heavy daily precipitation exceeding 25 mm. Accordingly, the hierarchical BMA (h-BMA) model is introduced in this study, designed for different precipitation classifications. Compared with the s-BMA model, the h-BMA model notably improves the probabilistic forecast skill for all precipitation thresholds throughout East Asia, particularly for heavy precipitation events. Moreover, the h-BMA model also improves the forecast reliability across various precipitation thresholds. A hierarchical EMOS (h-EMOS) model is also developed to validate the benefits of the precipitation classifications and further improves the forecast accuracy as expected. The prediction probability density functions of the hierarchical models are much sharper and more concentrated than those of the standard models. In general, the improvement in precipitation probabilistic forecast skill of the h-BMA model relative to the s-BMA model surpasses that of the h-EMOS model compared with the s-EMOS model.</p>","PeriodicalId":49825,"journal":{"name":"Meteorological Applications","volume":"32 2","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/met.70035","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143489717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heat waves harm human health and adversely impact the natural environment and society, especially in urban regions. Understanding the differences between heat waves in urban agglomerations and their driving mechanisms is essential for sustainable development. In this study, we investigate the spatiotemporal distribution of summertime heat waves and their association with sea surface temperature modes in two of China's most densely populated urban areas: the Beijing–Tianjin–Hebei (BTH) and the Yangtze River Economic Belt (YREB). The results indicate an increase in the frequency of heat waves for BTH and YREB by 0.02 times a−1 and 0.1 times a−1 and duration by 0.09d a−1 and 0.48d a−1, respectively. Regarding spatial distribution, the duration and frequency of BTH heat waves gradually decreased from northeast to southwest. In contrast, the heat waves in YREB were concentrated in the upper and parts of the lower reaches. The Atlantic Multidecadal Oscillation significantly influences heat waves in both the BTH and YREB regions. Nevertheless, the Pacific Decadal Oscillation, Indian Ocean Basin-Wide Index, and Cold-tongue ENSO Index primarily impact heat waves in the YREB region, with limited influence observed in the BTH region. This study provides a scientific basis for accurately identifying heat waves and understanding their changes, assisting decision-makers in formulating mitigation, adaptation strategies, and disaster prevention policies related to heat-induced consequences.
{"title":"A comparative analysis of heat waves over two major urban agglomerations in China","authors":"Xin Wang, Binghao Jia, Xiufen Li, Longhuan Wang","doi":"10.1002/met.70030","DOIUrl":"https://doi.org/10.1002/met.70030","url":null,"abstract":"<p>Heat waves harm human health and adversely impact the natural environment and society, especially in urban regions. Understanding the differences between heat waves in urban agglomerations and their driving mechanisms is essential for sustainable development. In this study, we investigate the spatiotemporal distribution of summertime heat waves and their association with sea surface temperature modes in two of China's most densely populated urban areas: the Beijing–Tianjin–Hebei (BTH) and the Yangtze River Economic Belt (YREB). The results indicate an increase in the frequency of heat waves for BTH and YREB by 0.02 times a<sup>−1</sup> and 0.1 times a<sup>−1</sup> and duration by 0.09d a<sup>−1</sup> and 0.48d a<sup>−1</sup>, respectively. Regarding spatial distribution, the duration and frequency of BTH heat waves gradually decreased from northeast to southwest. In contrast, the heat waves in YREB were concentrated in the upper and parts of the lower reaches. The Atlantic Multidecadal Oscillation significantly influences heat waves in both the BTH and YREB regions. Nevertheless, the Pacific Decadal Oscillation, Indian Ocean Basin-Wide Index, and Cold-tongue ENSO Index primarily impact heat waves in the YREB region, with limited influence observed in the BTH region. This study provides a scientific basis for accurately identifying heat waves and understanding their changes, assisting decision-makers in formulating mitigation, adaptation strategies, and disaster prevention policies related to heat-induced consequences.</p>","PeriodicalId":49825,"journal":{"name":"Meteorological Applications","volume":"32 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/met.70030","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143248692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>Exposure correction is necessary for removing the distortion effects induced by nonstandard local exposure in raw near-ground wind speed datasets. The accurate calculation of the exposure correction factor (<span></span><math>