Quarterly Journal of the Royal Meteorological Society最新文献

{"title":"Time variability and periodicities of cross‐regional hydroclimatic causation in the contiguous United States","authors":"Xueli Yang, Zhi‐Hua Wang, Qi Li, Ying‐Cheng Lai","doi":"10.1002/qj.4800","DOIUrl":"https://doi.org/10.1002/qj.4800","url":null,"abstract":"Identifying and understanding various causal relations are fundamental to climate dynamics for improving the predictive capacity of Earth system modeling. In particular, causality in Earth systems has manifest temporal periodicities, like physical climate variabilities. To unravel the characteristic frequency of causality in climate dynamics, we develop a data‐analytic framework based on a combination of causality detection and Hilbert spectral analysis, using a long‐term temperature and precipitation dataset in the contiguous United States. Using the Huang–Hilbert transform, we identify the intrinsic frequencies of cross‐regional causality for precipitation and temperature, ranging from interannual to interdecadal time scales. In addition, we analyze the spectra of the physical climate variabilities, including El Niño‐Southern Oscillation and Pacific Decadal Oscillation. It is found that the intrinsic causal frequencies are positively associated with the physics of the oscillations in the global climate system. The proposed methodology provides fresh insights into the causal connectivity in Earth's hydroclimatic system and its underlying mechanism as regulated by the characteristic low‐frequency variability associated with various climatic dynamics.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503272","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":"Is a more physical representation of aerosol chemistry needed for fog forecasting?","authors":"Moumita Bhowmik, Anupam Hazra, Sachin D. Ghude, Sandeep Wagh, Rituparna Chowdhury, Avinash N. Parde, Gaurav Govardhan, Ismail Gultepe, M. Rajeevan","doi":"10.1002/qj.4729","DOIUrl":"https://doi.org/10.1002/qj.4729","url":null,"abstract":"With the changing climate, the study of fog formation is essential due to the impact of the complexity of natural and anthropogenic aerosols. The evolution of the droplet size distribution in the presence of different aerosol species remains poorly understood. To make progress towards reducing the uncertainty of fog forecasts, the Eulerian–Lagrangian particle‐based small‐scale model for the diffusional growth of droplets is used to better understand the droplet activation and growth. The small‐scale model simulations are performed using observed data from the Winter Fog Experiment study over Indira Gandhi International Airport, New Delhi. The microphysical properties, such as droplet number concentrations (Nd) and liquid water content (LWC), important for fog simulation, are evaluated to gain more insights. The small‐scale simulations have shown the droplet microphysical properties at different evolutionary stages. The Nd and effective radius change with variations in LWC for different aerosol chemistries (i.e., organics, mix, and inorganic). The calculated visibility at small scale is also shown with the variation of Nd and LWC. This study compared visibility from an existing parametrization with parcel–direct numerical simulation calculation. The hygroscopicity , which is highly related to the activation of aerosols to condensation nuclei, is taken into account to demonstrate the contribution of aerosol chemistry to fog droplet formation. The results highlight that hygroscopicity is essential in the numerical model for fog and visibility prediction as the microphysical properties of fog are regulated by aerosol species.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503271","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 moisture budget perspective on Australian rainfall variability","authors":"Sunil Kumar Pariyar, Giovanni Liguori, Christian Jakob, Martin S. Singh, Michael J. Reeder, Michael A. Barnes","doi":"10.1002/qj.4778","DOIUrl":"https://doi.org/10.1002/qj.4778","url":null,"abstract":"Rainfall variability over Australia is revisited from the viewpoint of the atmospheric moisture budgets in three regions: the extratropics, Subtropics, and Tropics. The budgets are calculated using three‐hourly European Centre for Medium‐Range Weather Forecasts Reanalysis v5 (ERA5) and ERA5‐Land data between 1979 and 2022. The use of the moisture budget at short time‐scales enables the investigation of the relationship between synoptic weather‐scale processes and the longer term variability of the rainfall climate. The total variability in the vertically integrated moisture flux divergence (VIMD) is significantly larger than the evaporation minus precipitation (<jats:italic>E</jats:italic> − <jats:italic>P</jats:italic>), to a large extent due to the sub‐daily time‐scales. <jats:italic>E</jats:italic> − <jats:italic>P</jats:italic> is related more closely to moisture flux convergence in winter (summer) over south (north) Australia, suggesting a clear seasonality in the relationship between the two budget terms. The <jats:italic>E</jats:italic> − <jats:italic>P</jats:italic>–VIMD relationship is nearly in phase in the Tropics, whereas VIMD leads <jats:italic>E</jats:italic> − <jats:italic>P</jats:italic> by 9–15 hr with eastward‐propagating signals in the extratropics and Subtropics. Such seasonal and regional discrepancies in the relationship are attributed to the background state of moisture availability and temperature as represented by relative humidity and lifting condensation levels. The variability of the budget imbalance and its seasonality are dominated by the variability in VIMD. The imbalance reduces rapidly with temporal smoothing, with the storage term approaching zero at approximately 20 days, which can be thought of as making a transition time‐scale from high‐frequency weather‐related variability into slow‐varying background conditions. Weather‐related variability (cyclones, fronts, and thunderstorms) dominates the overall <jats:italic>E</jats:italic> − <jats:italic>P</jats:italic> variability in the extratropics and Subtropics, whereas slow‐varying background conditions contribute equally to the total variability in the Tropics.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141526696","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":"The performance of the CoMorph‐A convection package in global simulations with the Met Office Unified Model","authors":"A. P. Lock, M. Whitall, A. J. Stirling, K. D. Williams, S. L. Lavender, C. Morcrette, K. Matsubayashi, P. R. Field, G. Martin, M. Willett, J. Heming","doi":"10.1002/qj.4781","DOIUrl":"https://doi.org/10.1002/qj.4781","url":null,"abstract":"The impact on global simulations of a new package of physical parametrizations in the Met Office Unified Model is documented. The main component of the package is an entirely new convection scheme, CoMorph. This has a mass‐flux structure that allows initiation of buoyant ascent from any level and the ability for plumes of differing originating levels to coexist in a grid box. It has a different form of closure, where the mass flux of initiation is dependent on local instability, and an implicit numerical solution for detrainment that yields smooth timestep behaviour. The scheme is coupled more consistently to the cloud, microphysics, and boundary‐layer parametrizations and, as a result, significant changes to these have also been made. The package, called CoMorph‐A, has been tested in a variety of single‐column and idealized regimes. Here we test it in global configurations and evaluate it against observations using a range of standard metrics. Overall it is found to perform well against the control. Biases in the climatologies of the radiative fluxes are significantly reduced across the Tropics and subtropics, tropical and extratropical cyclone statistics are improved, and the Madden–Julian oscillation and other propagating tropical waves are strengthened. It also improves overall scores in numerical weather prediction trials, without revisions to the data assimilation. There is still work to do to improve the diurnal cycle of precipitation over land, where the peak remains too close to the middle of the day.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141526697","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 mechanism for coastal fog genesis at evening transition","authors":"Thomas J. Hintz, Kelly Y. Huang, Sebastian W. Hoch, Stef L. Bardoel, Saša Gaberšek, Ismail Gultepe, Jesus Ruiz‐Plancarte, Eric R. Pardyjak, Qing Wang, Harindra J. S. Fernando","doi":"10.1002/qj.4732","DOIUrl":"https://doi.org/10.1002/qj.4732","url":null,"abstract":"Transitional changes in the atmospheric boundary layer (ABL) are known to facilitate the onset of terrestrial fog, which is defined as a condition with near‐surface visibility &lt;1 km due to airborne water droplets. In particular, the evening transition from a daytime convective ABL to a night‐time stable ABL provides favorable conditions for fog. This article describes a local fog event observed during the evening transition at a Canadian islet in the north Atlantic known as Sable Island during the “Fog and Turbulence Interactions in the Marine Atmosphere (Fatima)” field campaign. The comprehensive set of data collected using a myriad of instruments covering a wide range of scales allowed identification of a novel mechanism underlying this fog event. Therein an ocean–land discontinuity created a flow regime consisting of several stacked boundary layers, interplay of which produced a thin low‐level cloud that then diffused downward to the surface, causing visibility reduction. This mechanism offers useful insights on the role of boundary layers, stratification, and turbulence in fog genesis over oceanic islands.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503273","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 machine‐learning approach to thunderstorm forecasting through post‐processing of simulation data","authors":"Kianusch Vahid Yousefnia, Tobias Bölle, Isabella Zöbisch, Thomas Gerz","doi":"10.1002/qj.4777","DOIUrl":"https://doi.org/10.1002/qj.4777","url":null,"abstract":"Thunderstorms pose a major hazard to society and the economy, which calls for reliable thunderstorm forecasts. In this work, we introduce SALAMA, a feedforward neural network model for identifying thunderstorm occurrence in numerical weather prediction (NWP) data. The model is trained on convection‐resolving ensemble forecasts over central Europe and lightning observations. Given only a set of pixel‐wise input parameters that are extracted from NWP data and related to thunderstorm development, SALAMA infers the probability of thunderstorm occurrence in a reliably calibrated manner. For lead times up to 11 h, we find a forecast skill superior to classification based only on NWP reflectivity. Varying the spatiotemporal criteria by which we associate lightning observations with NWP data, we show that the time‐scale for skillful thunderstorm predictions increases linearly with the spatial scale of the forecast.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141526698","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":"Dry‐air intrusion over India during break phases of the Indian summer monsoon in CMIP6 models","authors":"Rahul Singh, S. Sandeep","doi":"10.1002/qj.4788","DOIUrl":"https://doi.org/10.1002/qj.4788","url":null,"abstract":"Episodes of dry‐air intrusion over northern India have been observed during break phases of the Indian summer monsoon (ISM). Previous investigations have provided observational evidence of a significant reservoir of unsaturated air over the northern Arabian Sea, serving as the source of this dry‐air intrusion. It was also suggested that the monsoon low‐level jet, which typically transports moisture to continental India during the active phase, instead transports dry air during the break phase of the ISM. While the existence of dry‐air intrusion is well‐documented through observations, its representation in climate models remains uncertain. It is important to enhance our understanding of the process of dry‐air advection in climate models to assess their fidelity in simulating the climate over the region. In this study, we quantify the extent of dry‐air intrusion and examine its mechanisms in simulations from the sixth phase of the Coupled Model Intercomparison Project (CMIP6). Most CMIP6 models analysed in this study simulate the observed pattern of dry‐air advection over continental India realistically during the summer monsoon‐break phase. Some models also simulate dry‐air transport from West Asia, possibly due to an overly smoothed representation of orography. Furthermore, the majority of CMIP6 models successfully capture the intrinsic modes associated with the dry monsoon phase, as demonstrated by empirical orthogonal function analysis of low‐level zonal winds. Our analyses indicate that global climate models exhibit better skill in simulating dry processes of the monsoon compared with moist processes. These findings uncover previously underexplored aspects of the monsoon, which are essential for assessing future regional climate changes accurately.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141526699","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":"Persistent mixed‐phase states in adiabatic cloud parcels under idealised conditions","authors":"G. Abade, Daniel G. Albuquerque","doi":"10.1002/qj.4775","DOIUrl":"https://doi.org/10.1002/qj.4775","url":null,"abstract":"By assuming that liquid droplets and ice crystals within a computational grid box grow under the same conditions, mean‐field representations of mixed‐phase clouds in numerical models favour a quick cloud glaciation driven by the Wegener–Bergeron–Findeisen process. Consequently, maintenance of mixed‐phase states under the mean‐field approximation is conditioned to external dynamical forcing, such as sufficiently strong updraughts. In this work we go beyond the mean‐field representation and investigate the maintenance of mixed‐phase states in adiabatic (non‐entraining) cloud volumes by accounting for local variability in a particle's growth conditions in the turbulent cloud environment. This is done by using a Lagrangian microphysical scheme, where temperature and vapour mixing ratio are stochastic attributes attached to each cloud particle. Different dynamic scenarios show that microphysical variability and parametrised turbulence effects may significantly reduce cloud glaciation rates, resulting in much more resilient mixed‐phase states in idealised parcels containing non‐sedimenting and non‐aggregating cloud particles. We have stated a more refined criterion for the Wegener–Bergeron–Findeisen process activity in the bulk of a mixed‐phase cloud parcel (or computational grid box). This criterion is stated in terms of the conditional average supersaturations that are experienced by specific cloud particle types (liquid or ice), and not in terms of unconditional averages corresponding to parcel‐ or grid‐mean values of supersaturations. Formulation of a relation between conditional and unconditional average supersaturations poses an interesting closure problem in mixed‐phase cloud microphysics. Our stochastic microphysical model provides a Lagrangian closure to this problem and gives insights towards the development of a prognostic stochastic subgrid‐scale scheme for condensation/deposition in numerical models of mixed‐phase clouds.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141366568","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":"Quantifying the influence of atmospheric rivers on rainfall over the Jianghuai River Basin during the 2022 Mei‐yu season","authors":"Y. Zhang, Y. Han, Y. Xuan, H. Zhou, H. Gao, N. Yang","doi":"10.1002/qj.4758","DOIUrl":"https://doi.org/10.1002/qj.4758","url":null,"abstract":"Atmospheric rivers (ARs) are narrow, elongated belts of intense water vapor transport that often occur in mid‐latitude areas and are the primary drivers of heavy precipitation in these regions. This study investigates the impact of ARs on precipitation patterns in the Jianghuai River Basin during the Mei‐yu period. Focusing on a specific rainstorm event on June 27, 2022, we analyze atmospheric circulation, water vapor attributes, and transport trajectories. Three distinct classes of grids (Class A, significantly influenced by ARs; Class B, moderately affected; and Class C, untouched by ARs) are identified based on their response to ARs. Class A grids, located centrally, experience substantial precipitation, with a higher probability of rainstorm events. Class B grids, situated at a distance from ARs, exhibit moderate precipitation and a longer duration of rainy days. Class C grids, minimally affected by ARs, experience minimal precipitation with almost no chance of rainstorm events. The results from grid‐based analysis emphasize the localized influence of ARs, indicating a 8–30 times increase in precipitation intensity of Class A compared to Class C. The 23‐day Mei‐yu period is further categorized into AR days and non‐AR days, revealing that ARs amplify precipitation intensity by 2–5 times on average. Grid‐based and day‐based analyses provide complementary insights, with the former offering a broader spatial perspective and the latter emphasizing temporal distinctions. These findings underscore the nuanced influence of ARs on precipitation, emphasizing their role in extreme events and highlighting the importance of considering both spatial and temporal factors in understanding precipitation variability.","PeriodicalId":49646,"journal":{"name":"Quarterly Journal of the Royal Meteorological Society","volume":null,"pages":null},"PeriodicalIF":8.9,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141384899","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":"Ensemble forecasting: A foray of dynamics into the realm of statistics","authors":"Jie Feng, Zoltan Toth, Jing Zhang, Malaquias Peña","doi":"10.1002/qj.4745","DOIUrl":"https://doi.org/10.1002/qj.4745","url":null,"abstract":"Uncertain quantities are often described through statistical samples. Can samples for numerical weather forecasts be generated dynamically? At a great expense, they can. With statistically constrained perturbations, a cloud of initial states is created and then integrated forward in time. By now, this technique has become ubiquitous in weather and climate research and operations. Ensembles are widely used, with demonstrated value. The atmosphere evolves in a multidimensional phase space. Does a cloud of ensemble solutions encompass the evolution of the real atmosphere? Theoretically, random perturbations in high‐dimensional spaces have negligible projection in any direction, including the error in the best estimate, therefore consistently degrading that. As the bulk of the perturbation variance lies in the null space of error, samples in multidimensional space do not contain reality. An evaluation suggests that initial and short‐range forecast error and ensemble perturbations are random draws from a high‐dimensional domain we call the subspace of possible error. Error in any initial condition is partly a result of stochastic observational and assimilation noise, while perturbations explore other, mostly independent directions from the subspace of possible error that may have resulted from other configurations of stochastic noise. What benefits may arise from the deterministic projection of such noise? Consistent with theoretical expectations, ensemble members consistently degrade the skill of the unperturbed forecast until medium range. The mean and all other products derived from ensembles suffer an 18‐hour loss in forecast Information. Since Information is a sufficient statistic, any rational user can benefit more from the unperturbed, than from an ensemble of weather forecasts. Furthermore, case‐dependent variations in the distribution or spread of ensembles have no impact on commonly used metrics. Can alternative, statistical applications provide comparable, or even higher‐quality probabilistic and other products, at the fraction of the cost of running an ensemble?","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":"141269182","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}