Quarterly Journal of the Royal Meteorological Society最新文献

{"title":"Deep‐learning‐based downscaling of precipitation in the middle reaches of the Yellow River using residual‐based CNNs","authors":"He Fu, Jianing Guo, Chenguang Deng, Heng Liu, Jie Wu, Zhengguo Shi, Cailing Wang, Xiaoning Xie","doi":"10.1002/qj.4759","DOIUrl":"https://doi.org/10.1002/qj.4759","url":null,"abstract":"The middle reaches of the Yellow River (MRYR), located in northern China, are the transition zone between semi‐arid and semi‐humid climates. As one of the climate‐sensitive regions in China, MRYR has a fragile ecological environment and serious soil loss, which leads to geological disasters such as landslides, collapses, and mudslides caused by extreme precipitation. However, scarceness of high‐resolution precipitation data over MRYR limits assessment of the environmental impacts caused by climate change, especially for extreme precipitation. In this article, we design a Residual‐in‐Residual Dense Block based Network (RRDBNet) model for the statistical downscaling of precipitation in MRYR, and compare the proposed RRDBNet with a generalized linear regression model (GLM) and two popular deep‐learning‐based models. The multi‐level residuals and dense connectivity strategies introduced in RRDBNet help it to learn more abstract features and complex nonlinear relationships among climate variables to improve downscaling performance. The results show that the proposed RRDBNet has good performance in precipitation simulations, which can reproduce the spatial–temporal characteristics of high‐resolution precipitation well. RRDBNet reduces the root‐mean‐squared error (RMSE) by 19% and improves the Pearson correlation coefficient (CC) by 6% relative to GLM for climatology mean precipitation. Especially, RRDBNet has substantial improvements in extreme precipitation compared with other models. It reduces RMSE by 58% (79%) and improves CC by 38% (145%) relative to GLM for R95P (R99P), where R95P and R99P represent extreme precipitation and very extreme precipitation, respectively. For the probability density function of daily precipitation, it is further demonstrated that RRDBNet performs better as regards extreme precipitation frequency. Our results suggest that statistical downscaling based on RRDBNet may be an effective tool for historical and future climate simulations from global climate models.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamic channel selection based on vertical sensitivities for the assimilation of FY‐4A geostationary interferometric infrared sounder targeted observations","authors":"Yonghui Li, Wei Han, Wansuo Duan","doi":"10.1002/qj.4760","DOIUrl":"https://doi.org/10.1002/qj.4760","url":null,"abstract":"Target observations have garnered significant attention owing to their successful applications in enhancing forecasting skills of extreme weather events, particularly tropical cyclone (TC) events. The key step of implementing target observation is to determine the sensitive area in advance. Previous studies often obtained the sensitive areas for TC forecasting by vertically integrating the energy of optimal perturbation and taking the horizontal area of large energy, in an attempt to use it to represent roughly the sensitivity of the whole atmospheric layer. The advent of the geostationary interferometric infrared sounder on the FY‐4A satellite and then corresponding satellite data assimilation have opened up a new possibility for identifying the vertical sensitivity for TC forecasting to improve the forecasting skill. This article proposes a targeting satellite channel (TSC) approach to accurately capture the sensitivity along vertical directions of the atmosphere that allows one to preferentially select the channels whose observations locate on the sensitive vertical atmospheric layers. Numerical experiments demonstrate that, when preferentially assimilating the channel observations obtained from the TSC approach, the TC tracks achieve a considerably smaller forecast error than the information entropy channel selection approach. The TSC approach, therefore, has the potential for the satellite data assimilation to improve TC track forecasting skill very effectively, which can also provide guidance to targeting observations in field campaigns for TC forecasting.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141272348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A composite study of extratropical cyclones accompanied by split fronts in the Northwestern Pacific","authors":"Eigo Tochimoto, H. Niino","doi":"10.1002/qj.4774","DOIUrl":"https://doi.org/10.1002/qj.4774","url":null,"abstract":"The structure and environment of extratropical cyclones around East Asia that are accompanied by split fronts (SFs), hereafter referred to as SF cyclones, are examined using the Japanese 55‐year reanalysis dataset. The SFs are objectively and automatically detected with a thermal front parameter using equivalent potential temperature (). Previous statistical studies have shown that dry intrusion in the northern hemisphere occurs most frequently in winter; however, SFs occur more frequently in spring and autumn. In winter, SFs tend to occur at lower latitudes than in spring and autumn. A composite analysis in which the SF cyclones are simply superposed with respect to their centres indicates that the SFs tend to be located in the quadrants east and southeast of the cyclone centre, in accordance with previous case studies. For developing SF cyclones in the southern Northwestern Pacific (southern cyclone; SC) in autumn, a southward intrusion of low from the upper troposphere is the major contributor towards the formation of the SFs; for those in the northern Northwestern Pacific (northern cyclone; NC), a northward intrusion of low‐level high is the major contributor. For both SCs and NCs, high potential‐vorticity anomalies approach the cyclones from behind, suggesting that upper‐level troughs contribute to the formation of SFs by inducing ascent to the east and descent to the west of the upper‐level troughs.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141268836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the atmospheric conditions increasing fire danger in the Iberian Peninsula","authors":"Carolina Purificação, Cátia Campos, Alice Henkes, F. T. Couto","doi":"10.1002/qj.4776","DOIUrl":"https://doi.org/10.1002/qj.4776","url":null,"abstract":"The fire danger is particularly sensitive to meteorological conditions. The present study discusses the atmospheric conditions during three periods to evaluate how they can increase fire danger. A set of three convection‐permitting simulations was configured at 2.5 km resolution using the Meso‐NH model. In the first period, the intense surface heating induced by a heatwave favoured the development of the Iberian thermal low in July 2019, leading to the formation of precipitating systems and resulting in convective outflows that affected the central Iberian Peninsula. The outflows were shown to be an important feature in evaluating fire danger during the period; however, the simulation also highlighted the orographic effect as another phenomenon playing an important role in fire development and consequently enhancing the fire danger in some regions such as in the extreme southwest of Portugal. The orographic effect in this specific region was identified and analyzed in detail for two megafire events that occurred in Monchique in August 2003 and 2018. The Monchique Mountain's shape and orientation interacting with the airflow induced upslope and downslope winds that favoured the rapid propagation of the fire fronts in August 2018. The third experiment showed that the circulation of a sea breeze from the southern coast of Portugal may act as an enhancer for fire danger in the region when interacting with the regional mountain, such as verified in the 2003 megafire. The study shows that the fire danger over specific regions can be increased by different atmospheric phenomena and explored from atmospheric modelling. The convective outflows were an important factor enhancing fire danger; however, the orographic effect was confirmed as the main factor producing two megafires events in the extreme southwest of Portugal.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141269074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Irrigation impact on boundary layer and precipitation characteristics in Weather Research and Forecasting model simulations during LIAISE‐2021","authors":"Mireia Udina, Eric Peinó, Francesc Polls, Jordi Mercader, Iciar Guerrero, Arianna Valmassoi, Alexandre Paci, Joan Bech","doi":"10.1002/qj.4756","DOIUrl":"https://doi.org/10.1002/qj.4756","url":null,"abstract":"The Land Surface Interactions with the Atmosphere over the Iberian Semi‐arid Environment (LIAISE) campaign examined the impact of anthropization on the water cycle in terms of land–atmosphere–hydrology interactions. The objective of this study is to assess the effects of irrigation on the atmosphere and on precipitation in Weather Research and Forecasting model simulations during the LIAISE special observation period in July 2021. Comparisons between simulations and observations show better verification scores for air temperature, humidity, and wind speed and direction when the model included the irrigation parametrization, improving the model warm and dry bias at 2 m over irrigated areas. Other changes found are the weakening of the sea breeze circulation and a more realistic surface energy partitioning representation. The boundary‐layer height is lowered in the vicinity of irrigated areas, causing a decrease in the lifting condensation level and the level of free convection, which induce increases in convective available potential energy and convective inhibition. Precipitation differences between simulations become relevant for smaller areas, close to the irrigated land. When convection is parametrized, simulations including irrigation tend to produce a decrease in rainfall (negative feedback), whereas convection‐permitting simulations produce an increase (positive feedback), although the latter underestimates substantially the observed precipitation field. In addition, irrigation activation decreases the areas exceeding moderate hourly precipitation intensities in all simulations. There is a local impact of irrigated land on model‐resolved precipitation accumulations and intensities, although including the irrigation parametrization did not improve the representation of the observed precipitation field, as probably the precipitation systems during the LIAISE special observation period in July 2021 were mostly driven by larger scale perturbations or mesoscale systems, more than by local processes. Results reported here not only contribute to enhance our understanding of irrigation effects upon precipitation but also demonstrate the need to include irrigation parametrizations in numerical forecasts to overcome the biases found.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141195378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the role of boreal summer intraseasonal oscillation on the severe heatwave of May 2015 over India","authors":"Tukaram Zore, Kiranmayi Landu","doi":"10.1002/qj.4765","DOIUrl":"https://doi.org/10.1002/qj.4765","url":null,"abstract":"In May 2015, the southeastern coastal states of India encountered one of the deadliest heatwaves in Indian history. Researchers have extensively studied the event to understand the underlying mechanisms and concluded that horizontal warm‐air advection from northwestern parts of India and adiabatic heating were the main attributing factors for the event. However, the large‐scale atmospheric processes that led to these conditions have not been thoroughly explored. In the present study, we show that this event was largely associated with the boreal summer intraseasonal oscillation (BSISO) that is prominent during this season. Our analysis shows that the BSISO dry phase lead to a persistent high‐pressure system, with anomalous subsidence favoring adiabatic heating and anticyclonic circulation anomalies increasing the northwesterly warm‐air advection. It is shown that a 55% to 75% contribution to the maximum surface air temperature (SAT) anomalies during the heatwave period can be attributed to BSISO‐related temperature anomalies. Furthermore, the results show that, in the absence of BSISO, the heat event would have dissipated with 1–2 hot days with much less intensity and the presence of the BSISO dry phase extended the heatwave duration by six days. The impact of BSISO on this heatwave was further substantiated by sensitivity experiments using the Weather Research and Forecasting (WRF) model. This analysis emphasizes that improving the forecasting skills of BSISO may facilitate the subseasonal forecast of local heatwave events.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141195308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of simulated rain intensity and kinetic energy to aerosols and warm‐rain microphysics during the extreme event of July 2021 in Belgium","authors":"K. Van Weverberg, N. Ghilain, E. Goudenhoofdt, M. Barbier, E. Koistinen, S. Doutreloup, B. Van Schaeybroeck, A. Frankl, P. Field","doi":"10.1002/qj.4761","DOIUrl":"https://doi.org/10.1002/qj.4761","url":null,"abstract":"This article presents an evaluation and sensitivity analysis of km‐scale simulations of an unprecedented extreme rainfall event over Europe, with a specific focus on sub‐hourly extremes, size distributions, and kinetic energy (KE) of rain. These variables are critical for hydrological applications, such as flood forecasting or soil‐loss monitoring, but are rarely directly obtained from numerical weather prediction (NWP) models. The simulations presented here reproduce the overall characteristics of the event, but overestimate the extreme rain rates. The rain rate–KE relation was well‐captured, despite too large volume‐mean drop diameters. Amongst the sensitivities investigated, the representation of the raindrop self‐collection–breakup equilibrium and the raindrop size‐distribution shape were found to have the most profound impact on the rainfall characteristics. While extreme rain rates varied within 30%, the rain KE varied by a factor of four between the realistic perturbations to the microphysical assumptions. Changes to the aerosol concentration and rain terminal velocity relations were found to have a relatively smaller impact. Given the large uncertainties, a continued effort to improve the model physics will be indispensable to estimate rain intensities and KE reliably for direct hydrological applications.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CERRA, the Copernicus European Regional Reanalysis system","authors":"Martin Ridal, Eric Bazile, Patrick Le Moigne, Roger Randriamampianina, Semjon Schimanke, Ulf Andrae, Lars Berggren, Pierre Brousseau, Per Dahlgren, Lisette Edvinsson, Adam El‐Said, Michael Glinton, Susanna Hagelin, Susanna Hopsch, Ludvig Isaksson, Paulo Medeiros, Esbjörn Olsson, Per Unden, Zheng Qi Wang","doi":"10.1002/qj.4764","DOIUrl":"https://doi.org/10.1002/qj.4764","url":null,"abstract":"A regional reanalysis has been produced for a domain covering entire Europe from 1984 to 2021. The reanalysis is produced as part of the Copernicus Climate Change Service. The Service provides the high‐resolution deterministic Copernicus European Regional Reanalysis (CERRA), run at a horizontal resolution of 5.5 km, a 10‐member ensemble run at 11‐km resolution as well as an offline surface analysis, CERRA‐Land. CERRA‐EDA uses an ensemble data assimilation (EDA) technique to perturb the initial condition of the different members. Apart from the horizontal resolution the CERRA and CERRA‐EDA setups are the same; for example, the same data assimilation scheme, same physics parameterization as well as the same vertical levels. These new systems are built from HARMONIE cy40 version, including some back‐phased physics from a newer model version (cy42). Conventional observations, satellite‐based radiances, atmospheric motion vector winds and bending angle from radio occultation observations are used. In addition, ground‐based zenith total delay (ZTD) from global navigational satellite systems (GNSS) and local surface observations, rescued from historical archives at the local National Meteorological Services, are used. Another new feature is the construction of the background error statistics for the data assimilation. Information from the ensemble run, CERRA‐EDA, is used in the derivation of the background error statistics for the high‐resolution CERRA runs. These background error statistics are updated every second day. By doing so, daily environment variation is taken into account as well as all variations over the 37 years of production. The reanalyses and reforecasts from CERRA show an added value compared to the global ERA5 for almost all variables at the surface level. This becomes particularly clear when selecting smaller areas with complex terrain where the high resolution is beneficial. In the free atmosphere it is primarily the analyses and short forecasts, 3–6 hours, that give an added value.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Flux‐gradient relations and their dependence on turbulence anisotropy","authors":"Samuele Mosso, Marc Calaf, Ivana Stiperski","doi":"10.1002/qj.4762","DOIUrl":"https://doi.org/10.1002/qj.4762","url":null,"abstract":"Monin–Obukhov similarity theory (MOST) is used in virtually all Earth System Models to parametrize the near‐surface turbulent exchanges and mean variable profiles. Despite its widespread use, there is high uncertainty in the literature about the appropriate parametrizations to use. In addition, MOST has limitations in very stable and unstable regimes, over heterogeneous terrain and complex orography, and has been found to represent the surface fluxes incorrectly. A new approach including turbulence anisotropy as a non‐dimensional scaling parameter has recently been developed and has been shown to overcome these limitations and generalize the flux‐variance relations to complex terrain. In this article, we analyze the flux‐gradient relations for five well‐known datasets, ranging from flat and homogeneous to slightly complex terrain. The scaling relations show substantial scatter and highlight the uncertainty in the choice of parametrization even over canonical conditions. We show that, by including information on turbulence anisotropy as an additional scaling parameter, the original scatter becomes well bounded and new formulations can be developed that drastically improve the accuracy of the flux‐gradient relations for wind shear () in unstable conditions and for temperature gradient () in both unstable and stable regimes. This analysis shows that both and are strongly dependent on turbulence anisotropy and allows us finally to settle the extensively discussed free convection regime for , which clearly exhibits a power law when anisotropy is accounted for. Furthermore, we show that the eddy diffusivities for momentum and heat and the turbulent Prandtl number are strongly dependent on anisotropy and that the latter goes to zero in the free convection limit. These results highlight the necessity to include anisotropy in the study of near‐surface atmospheric turbulence and lead the way for theoretically more robust simulations of the boundary layer over complex terrain.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Urban influence on convective precipitation in the Paris region: Hectometric ensemble simulations in a case study","authors":"Arnaud Forster, Clotilde Augros, Valéry Masson","doi":"10.1002/qj.4749","DOIUrl":"https://doi.org/10.1002/qj.4749","url":null,"abstract":"The purpose of this study is to investigate the influence of the urban environment of the Paris region on an isolated convective cell that formed downwind of the city on May 7, 2022, using the Meso‐NH research atmospheric model at a horizontal scale of 300 m. To account for all sources of forecast uncertainty, the initial and lateral boundary conditions of the simulations are provided by an ensemble prediction system. A multi‐layer urban scheme is used to represent the influence of buildings on the airflow accurately. Two sets of ensemble simulations are performed: the first set (URB) uses a fine‐scale surface description of the city, while the second set (NOURB) replaces urban surfaces with vegetation. This sensitivity test shows that, despite the high variability of simulated precipitation within the ensemble, the city of Paris plays a statistically significant role in the initiation of convection in this case. Convective cells are initiated over the city for several members of the URB ensemble, while almost no precipitation is simulated for the same members of the NOURB ensemble. The mean 6‐h rainfall accumulation of the URB ensemble is increased by 70% over Paris (compared with the NOURB ensemble) and no statistically significant trend is found around the city. The analysis reveals that the capital experiences a higher sensible heat flux due to drier and warmer air, resulting in enhanced vertical velocities and an increase in boundary‐layer height in the URB ensemble. Additionally, the total water content and cloud fraction over Paris are intensified, leading to more precipitation. These findings suggest that urbanisation has a notable impact on convection and precipitation processes in this case.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141171320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}