Monthly Weather Review最新文献_第3页

Asymmetries During Eyewall Replacement Cycles of Hurricane Ivan (2004) 伊万飓风（2004 年）眼壁更换周期中的不对称现象

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-15 DOI: 10.1175/mwr-d-23-0129.1

Bruno S. Rojas, A. Didlake, Jun A. Zhang

{"title":"Asymmetries During Eyewall Replacement Cycles of Hurricane Ivan (2004)","authors":"Bruno S. Rojas, A. Didlake, Jun A. Zhang","doi":"10.1175/mwr-d-23-0129.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0129.1","url":null,"abstract":"\u0000The physical processes that govern eyewall replacement cycles (ERCs) in tropical cyclones (TCs) are not yet fully understood. In particular, asymmetric structures within the TC inner core have an uncertain role in ERC dynamics. This study analyzes the kinematic and precipitation asymmetric structures during successive ERCs in Hurricane Ivan (2004) using airborne Doppler radar observations. The azimuthal locations of these asymmetries are analyzed relative to the deep-layer (850-200 hPa) environmental wind shear vector. Two ERCs were analyzed at different stages of their evolution. During the concentric eyewall stage of the first ERC, the outer eyewall updrafts were strongest in the left-of-shear half, which also coincided with mesoscale descending inflow (MDI) just radially outward. Enhanced low-level convergence, updrafts, and MDI were collocated in an zone spiraling inward towards the strongest outer eyewall updrafts, suggesting that the vertical velocity asymmetry in the outer eyewall was possibly forced by a stratiform-induced cold pool similar to MDI impacts seen in past TC studies. During the final stage of the second ERC, the outer eyewall (now the singular primary eyewall) experienced an upwind shift in the precipitation and vertical velocity asymmetries. The updraft maximum shifted from the downshear-left quadrant to the downshear-right quadrant, and the precipitation maximum (downwind of the updraft maximum) shifted from left-of-shear to the downshear direction. This shift corroborates previous studies, which hypothesize that at the end of an ERC, the forcing mechanism that drives the eyewall vertical velocity asymmetry transitions from MDI/cold-pool processes to direct interaction with the environmental wind shear.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140972570","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}

引用次数: 0

Superobbing and Thinning Scales for All-sky Humidity Sounder Assimilation 用于全天空湿度探测仪同化的超变和稀化尺度

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-15 DOI: 10.1175/mwr-d-24-0020.1

David I. Duncan, Niels Bormann, Alan J. Geer, Peter Weston

{"title":"Superobbing and Thinning Scales for All-sky Humidity Sounder Assimilation","authors":"David I. Duncan, Niels Bormann, Alan J. Geer, Peter Weston","doi":"10.1175/mwr-d-24-0020.1","DOIUrl":"https://doi.org/10.1175/mwr-d-24-0020.1","url":null,"abstract":"\u0000Humidity sounder radiances are currently thinned to 110 km spacing prior to assimilation at ECMWF and used with no averaging applied. In this paper, the thinning scale and possible averaging of all-sky humidity sounder observations into “superobs” are considered. The short- and medium-range forecast impacts of changing the thinning and averaging scales of humidity sounder radiances prior to the data assimilation are investigated separately and then together. Superobbing acts as a low-pass filter and provides smoother images of departures, decreasing the effective sensor noise and thus the standard deviation of background departures, marginally for 183GHz channels (5-15%) and significantly for 118GHz channels (5-55%). Observations are thus more representative of the model effective resolution, with a better utilisation of total information content than thinning native-resolution radiances, as less information is discarded. Whether changed in isolation or combination, the additions of data via superobbing and finer thinning are both shown to markedly improve background fits to independent observations, indicative of better short-range forecasts of humidity and improved winds via the 4D-Var tracer effect. Wind forecasts in the Southern Hemisphere are slightly improved in the medium-range. A final configuration is tested at the resolution of the current operational model, with humidity sounder radiances averaged into 50 km superobs with 70 km spacing. This provides about 140% more radiances for assimilation and more finely detailed maps to analyse mesoscale features. The forecast impact of this change is larger in testing with higher model and data assimilation resolutions, showing the scale-dependence of such decisions and the expected performance in an operational configuration.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140972988","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}

引用次数: 0

Climatological aspects of notable tornado events in Chile 智利著名龙卷风事件的气候学方面

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-14 DOI: 10.1175/mwr-d-23-0249.1

Julio C. Marín, Felipe Gutiérrez, Vittorio A. Gensini, Bradford S. Barrett, Diana Pozo, Martín Jacques-Coper, D. Veloso-Aguila

{"title":"Climatological aspects of notable tornado events in Chile","authors":"Julio C. Marín, Felipe Gutiérrez, Vittorio A. Gensini, Bradford S. Barrett, Diana Pozo, Martín Jacques-Coper, D. Veloso-Aguila","doi":"10.1175/mwr-d-23-0249.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0249.1","url":null,"abstract":"\u0000Tornadoes in Chile seem to develop in what are called “high-shear, low-CAPE” (HSLC) environments. An analysis of convective parameters from the ERA5 reanalysis during sixteen notable tornadoes in Chile showed that several increased markedly before the time of the reports. The significant tornado parameter (STP) was able to discriminate the timing and location of the tornadoes, even though it was not created with that goal. We established thresholds for the Severe Hazards in Environments with Reduced Buoyancy (SHERBE) parameter (≥1) and the STP (≤−0.3) to further identify days favorable for tornado activity in Chile. The SHERBE and STP parameters were then used to conduct a climatological analysis from 1959–2021 of the seasonal, interannual, and latitudinal variation of the environments that might favor tornadoes. Both parameters were found to have a strong annual cycle. The largest magnitudes of STP were found to be generally confined to south-central Chile, in agreement with the (sparse) tornado record. The probability of a day with both SHERBE and STP values beyond their thresholds was greatest between May and August, which aligns with the months with the most tornado reports. The number of days with both SHERBE and STP beyond their respective thresholds was found to fluctuate interanually. This result warrants further study given the known interannual variability of synoptic and mesoscale weather in Chile. The results of this study extend our understanding of tornado environments in Chile and provide insight into their spatio-temporal variability.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140979333","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}

引用次数: 0

How does vertical wind shear influence updraft characteristics and hydrometeor distributions in supercell thunderstorms? 垂直风切变如何影响超级雷暴中的上升气流特征和水流分布？

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-02 DOI: 10.1175/mwr-d-23-0166.1

J. Mulholland, C. Nowotarski, John M. Peters, Hugh Morrison, Erik R. Nielsen

{"title":"How does vertical wind shear influence updraft characteristics and hydrometeor distributions in supercell thunderstorms?","authors":"J. Mulholland, C. Nowotarski, John M. Peters, Hugh Morrison, Erik R. Nielsen","doi":"10.1175/mwr-d-23-0166.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0166.1","url":null,"abstract":"\u0000Vertical wind shear is known to affect supercell thunderstorms by displacing updraft hydrometeor mass downshear, thereby facilitating the storms’ longevity. Shear also impacts the size of supercell updrafts, with stronger shear leading to wider, less dilute, and stronger updrafts with likely greater hydrometeor production. To more clearly define the role of shear across different vertical layers on hydrometeor concentrations and displacements relative to supercell updrafts, a suite of idealized numerical model simulations of supercells was conducted. Shear magnitudes were systematically varied across the 0–1 km, 1–6 km, and 6–12 km AGL layers while the thermodynamic environment was held fixed. Simulations show that as shear magnitude increases, especially from 1–6 km, updrafts become wider and less dilute with an increase in hydrometeor loading, along with an increase in the low-level precipitation area/rate and total precipitation accumulation. Even with greater updraft hydrometeor loading amid stronger shear, updrafts are more intense in stronger shear simulations due to larger thermal buoyancy owing to wider, less dilute updraft cores. Furthermore, downshear hydrometeor displacements are larger in environments with stronger 1–6 km shear. In contrast, there is relatively less sensitivity of hydrometeor concentrations and displacements to variations in either 0–1 km or 6–12 km shear. Results are consistent across free tropospheric relative humidity sensitivity simulations, which show an increase in updraft size and hydrometeor mass with increasing free tropospheric relative humidity owing to a reduction in entrainment-driven dilution for wider updrafts in moister environments.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141130149","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}

引用次数: 0

Model Predictability of Hail Precipitation with a Moderate Hailstorm Case: Part II. Impact of Improved Treatment of Graupel in Thompson-Eidhammer Microphysics Scheme 中度冰雹案例中冰雹降水的模型可预测性：第二部分.改进汤普森-艾德哈默尔微物理方案中格拉贝尔处理方法的影响

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-01 DOI: 10.1175/mwr-d-23-0179.1

Rumeng Li, Juanzhen Sun, Qinghong Zhang, Anders A. Jensen, Sarah Tessendorf

{"title":"Model Predictability of Hail Precipitation with a Moderate Hailstorm Case: Part II. Impact of Improved Treatment of Graupel in Thompson-Eidhammer Microphysics Scheme","authors":"Rumeng Li, Juanzhen Sun, Qinghong Zhang, Anders A. Jensen, Sarah Tessendorf","doi":"10.1175/mwr-d-23-0179.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0179.1","url":null,"abstract":"\u0000Explicit simulation of hailstorms remains a challenge partly due to the lack of accurate representations of both initial conditions and microphysical processes. Using a moderate hailstorm case that occurred in Beijing on June 10, 2016, the impact of the initial conditions on explicit hail prediction has been studied in part I of this two-part work via high-resolution data assimilation. This part II paper examines the role of improved graupel treatment by comparing the recently upgraded Thompson-Eidhammer microphysics scheme (MP38) with two previous versions. MP38 is a double-moment hail-aware scheme with the ability to additionally predict graupel number concentration and density. This case study showed that the addition of these predictive variables improved the simulation of the mass-weighted mean diameter of hail and thereby reduced the overestimation of hail size. However, the hail size was significantly underpredicted without the prediction of hail density, indicating that both quantities must be prognosed for skillful hail prediction. It was further shown that the revised graupel treatment also influenced hailstorm dynamics. The smaller hail size in MP38 led to a stronger graupel melting process, which further promoted a stronger cold pool and downdraft. By assessing the efficiency of the upgraded Thompson-Eidhammer microphysics scheme, the current study shed some light on the importance of accurate representation of microphysical processes in numerical models for explicit hailstorm prediction.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141035615","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}

引用次数: 0

ST-TransNet: A Spatiotemporal Transformer Network for Uncertainty Estimation from a Single Deterministic Precipitation Forecast ST-TransNet：用于从单一确定性降水预报中估计不确定性的时空变压器网络

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-01 DOI: 10.1175/mwr-d-23-0097.1

Jingnan Wang, Xiaodong Wang, Jiping Guan, Lifeng Zhang, Tao Chang, W. Yu

{"title":"ST-TransNet: A Spatiotemporal Transformer Network for Uncertainty Estimation from a Single Deterministic Precipitation Forecast","authors":"Jingnan Wang, Xiaodong Wang, Jiping Guan, Lifeng Zhang, Tao Chang, W. Yu","doi":"10.1175/mwr-d-23-0097.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0097.1","url":null,"abstract":"\u0000The forecast uncertainty, particularly for precipitation, serves as a crucial indicator of the reliability of deterministic forecasts. Traditionally, forecast uncertainty is estimated by ensemble forecasting, which is computationally expensive since the forecast model is run multiple times with perturbations. Recently, deep learning methods have been explored to learn the statistical properties of ensemble prediction systems due to their low computational costs. However, accurately and effectively capturing the uncertainty information in precipitation forecasts remains challenging. In this study, we present a novel spatiotemporal transformer network (ST-TransNet) as an alternative approach to estimate uncertainty with ensemble spread and probabilistic forecasts, by learning from historical ensemble forecasts. ST-TransNet features a hierarchical structure for extracting multiscale features and incorporates a spatiotemporal transformer module with window-based attention to capture correlations in both spatial and temporal dimensions. Additionally, window-based attention can not only extract local precipitation patterns but also reduce computational costs. The proposed ST-TransNet is evaluated on the TIGGE ensemble forecast dataset and Global Precipitation Measurement (GPM) precipitation products. Results show that ST-TransNet outperforms both traditional and deep learning methods across various metrics. Case studies further demonstrate its ability to generate reasonable and accurate spread and probability forecasts from a single deterministic precipitation forecast. It demonstrates the capacity and efficiency of neural networks in estimating precipitation forecast uncertainty.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141049230","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}

引用次数: 0

The Subseasonal Feedback of Extreme Anomalous Tibetan Plateau Snow Cover Events on the Atmosphere 青藏高原极端异常积雪事件对大气的亚季节反馈

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-05-01 DOI: 10.1175/mwr-d-23-0175.1

Yumeng Liu, Wenkai Li

{"title":"The Subseasonal Feedback of Extreme Anomalous Tibetan Plateau Snow Cover Events on the Atmosphere","authors":"Yumeng Liu, Wenkai Li","doi":"10.1175/mwr-d-23-0175.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0175.1","url":null,"abstract":"\u0000Tibetan Plateau snow cover exhibits notable subseasonal variability and plays a crucial role in influencing the atmosphere. This study employs numerical experiments to investigate the atmospheric feedback resulting from extreme anomalous snow cover events on the Tibetan Plateau, with a focus on both local and nonlocal atmospheric temperatures. The findings reveal that diabatic heating, directly induced by these events, leads to a local surface energy cooling response over the Tibetan Plateau, contributing to a reduction in local temperatures. This cooling effect amplifies local atmospheric temperature anomalies associated with extreme anomalous Tibetan Plateau snow cover events, constituting approximately 50% of the total final local surface air temperature anomalies. Furthermore, the Tibetan Plateau snow cover, through adiabatic processes, exerts a nonlocal influence on atmospheric temperature and circulation. The atmospheric temperature responses downstream of the Tibetan Plateau vary at different heights and regions, featuring both cold and warm anomaly responses. These variations depend on the relative contributions of horizontal advection and vertical advection in adiabatic heating.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141037643","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}

引用次数: 0

Top-down phenomenon observed in the outer rainbands of Typhoon Maysak (2020): insights from the comparative analysis of cloud and precipitation microphysics with a typical precipitation event in Northeast China 台风 "麦莎克"（2020 年）外围雨带观测到的自上而下现象：云和降水微物理与中国东北典型降水事件对比分析的启示

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-04-24 DOI: 10.1175/mwr-d-23-0259.1

Tianao Liu, Yilun Chen, Haosheng Zuo, A. Zhang, Xiao Pan, Shumin Chen, Weibiao Li

{"title":"Top-down phenomenon observed in the outer rainbands of Typhoon Maysak (2020): insights from the comparative analysis of cloud and precipitation microphysics with a typical precipitation event in Northeast China","authors":"Tianao Liu, Yilun Chen, Haosheng Zuo, A. Zhang, Xiao Pan, Shumin Chen, Weibiao Li","doi":"10.1175/mwr-d-23-0259.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0259.1","url":null,"abstract":"\u0000Cloud and precipitation microphysics in tropical cyclones (TCs) moving towards Northeast China may exhibit significant distinctions compared with the typical precipitation of this region. In this study, observations from ground-based Particle Size Velocity (Parsivel) disdrometers in Liaoning Province, China, and cloud property data from the Himawari geostationary satellite, were utilized to analyze the raindrop size distribution (DSD) characteristics and cloud vertical evolution associated with the outer rainbands of Typhoon Maysak (2020). A comparative analysis was conducted with a typical precipitation event in Northeast China induced by a cold vortex (cold-core low). Our findings reveal distinctive DSD characteristics related to the TC, where medium-sized raindrops dominate, with a smaller diameter but higher concentration in the TC case compared to the typical cold-vortex-induced precipitation case in Northeast China. Convective precipitation falls between maritime-like and continental-like patterns, leaning more towards continental convection. This varies significantly with TCs in Southeast China, but is similar to that observed in coastal-front-like rainbands, suggesting extratropical influence. A detailed analysis of the vertical profile of cloud droplets shows a unique “top-down” phenomenon during the extratropical transition process of the TC, where the development of lower-level clouds follows that of upper-level clouds, inconsistent with previous studies and the case for comparison. Further investigation indicates the significant role of the intrusion of dry and cold air from upper levels and the presence of high humidity in low levels in driving this phenomenon. Our results will provide novel insights into cloud and precipitation microphysics associated with TCs in mid-latitude regions.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140662614","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}

引用次数: 0

A Climatology of Convective Precipitation over Europe 欧洲对流降水气候学

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-04-23 DOI: 10.1175/mwr-d-23-0156.1

Kelly Lombardo, Miranda Bitting

{"title":"A Climatology of Convective Precipitation over Europe","authors":"Kelly Lombardo, Miranda Bitting","doi":"10.1175/mwr-d-23-0156.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0156.1","url":null,"abstract":"\u0000The annual, seasonal, and diurnal spatiotemporal heavy convective precipitation patterns over a pan-European domain are analyzed in this study using a combination of datasets, including the IMERG precipitation rate product, E-OBS ground-based precipitation gauge data, EURADCLIM climatological gauge-adjusted radar precipitation dataset, OPERA ground-based radar derived precipitation rates, and ERA5 total and convective precipitation products. ATDnet lightning data is used in conjunction with IMERG and EURADCLIM precipitation rates with an imposed threshold of 10 mm hr−1 to classify precipitation as convective. Annually, the largest convective precipitation accumulations are over the European seas and coastlines. In summer, convective precipitation is more common over the European continent, though relatively large accumulations exist over the northern coastal waters and the southern seas, with a seasonal localized maximum over the northern Adriatic Sea. Activity shifts southward to the Mediterranean and its coastlines in autumn and winter, with maxima over the Ionian Sea, the eastern Adriatic Sea, and the adjacent coastline. Over the continent, 1 – 10% of the total precipitation accumulated is classified as convective, increasing to 10 – 40% over the surrounding seas. In contrast, 30 – 50 % of ERA5 precipitation accumulations over land is produced by the convective parameterization scheme and 40 – 60% over the seas; however, only 1% of ERA5 convective precipitation accumulations are from rain rates exceeding 10 mm hr−1. Regional analyses indicate that convective precipitation rates over the inland mountains follow diurnal heating, though little to no diurnal pattern exists in convective precipitation rates over the seas and coastal mountains.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140667902","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}

引用次数: 0

The influence of atmospheric bores on nocturnal convection initiation in weakly forced synoptic environments 大气膛对弱强迫合流环境中夜间对流启动的影响

IF 3.2 3区地球科学

Monthly Weather Review Pub Date : 2024-04-23 DOI: 10.1175/mwr-d-23-0080.1

D. Reif, H. Bluestein, David B. Parsons

{"title":"The influence of atmospheric bores on nocturnal convection initiation in weakly forced synoptic environments","authors":"D. Reif, H. Bluestein, David B. Parsons","doi":"10.1175/mwr-d-23-0080.1","DOIUrl":"https://doi.org/10.1175/mwr-d-23-0080.1","url":null,"abstract":"\u0000This study creates a composite sounding for nocturnal convection initiation (CI) events under weakly forced conditions and utilizes idealized numerical simulations to assess the impact of atmospheric bores on these environments. Thirteen soundings were used to create this composite sounding. Common conditions associated with these weakly forced environments include a nocturnal low-level jet and a Brunt-Väisälä frequency of 0.011 s−1 above 900 hPa. The median lift needed for parcels to realize any convective instability is 490 m, the median convective-available potential energy of these convectively unstable parcels is 992 J kg−1, and the median initial pressure of these parcels is 800 hPa. An idealized numerical simulation was utilized to examine the potential influence of bores on CI in an environment based on the composite sounding. The characteristics of the simulated bore was representative of observed bores. The vertical velocities associated with this simulated bore was between 1 and 2 m s−1, and the net upward displacement of parcels was between 400 and 650 m. The vertical displacement of air parcels has two notable phases: lift by the bore itself and smaller-scale lift that occurs 100 – 150 km ahead of the bore passage. The pre-bore lift is between 50 and 200 m and appears to be related to low-frequency waves ahead of the bores. The lift with these waves was maximized in the low- to mid-troposphere between 1 km and 4 km AGL, and this lift may play a role in assisting CI in these otherwise weakly forced environments.","PeriodicalId":18824,"journal":{"name":"Monthly Weather Review","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140669827","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}

引用次数: 0