{"title":"Modulation of diurnal variation in rainfall associated with tropical cyclones over the East Asia–Western North Pacific region by environmental vertical wind shear","authors":"Na Wei, Qian Wang, Xinghai Zhang, Dajun Zhao","doi":"10.1002/asl.1281","DOIUrl":"https://doi.org/10.1002/asl.1281","url":null,"abstract":"<p>Vertical wind shear (VWS), as an important dynamic factor influencing tropical cyclone rainfall (TCR), has a remarkable diurnal cycle of variation over the East Asia–western North Pacific region. The magnitude of tropical cyclone (TC)-experienced VWS has enhanced amplitude but different phases over the South China Sea (SCS) and coastal East China (CEC) compared with that over the open ocean. Diurnal variation in TCR over the SCS shows statistically significant correlation with that of VWS. The convection concentrated in the downshear-left quadrant strengthens markedly when VWS becomes large, thereby delaying the peak rainfall in the inner core of the TC and enhancing the amplitude of the diurnal cycle of TCR at ~09 local standard time. Over CEC, the diurnal signal of TCR is very weak but statistically significant in the downshear-left and upshear-right quadrants with opposite phase, illustrating the change in asymmetry of the spatial distribution of TCR induced by the large VWS diurnal cycle. The findings of this study could provide reference for improved forecasting of TCR on the fine temporal scale.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1281","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119395","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}
Kan Yi, Chenqi Wang, Yunfei Zhang, Xiang Li, Jian Wang, Renqiang Wen, Mengjiao Du
{"title":"Skillful seasonal prediction of the boreal summer Pacific–Japan teleconnection pattern","authors":"Kan Yi, Chenqi Wang, Yunfei Zhang, Xiang Li, Jian Wang, Renqiang Wen, Mengjiao Du","doi":"10.1002/asl.1273","DOIUrl":"https://doi.org/10.1002/asl.1273","url":null,"abstract":"<p>The Pacific–Japan (PJ) teleconnection pattern, a dominant mode of atmospheric variability over the western North Pacific during boreal summer, is pivotal in shaping regional climate dynamics. Despite its important implications, accurately predicting the PJ pattern remains challenging due to inherent model biases and uncertainties. This study delves into the impact of model biases on the prediction skill of the PJ pattern and evaluates its predictability using outputs from three operational seasonal forecast models. Our findings elucidate that the spatial structure of the PJ pattern simulated by models introduces substantial diversities in prediction skills. By discerning the variance in PJ teleconnection simulation among models, we unveil the high predictability of the PJ pattern, showcasing its capability for accurate forecasts up to 3 months in advance within the current seasonal forecast models. The predictability of the PJ pattern stems from concurrent El Niño–Southern Oscillation-related sea surface temperature anomalies and its corresponding atmospheric teleconnection processes. Our research underscores the necessity of accounting for model biases in predicting the PJ pattern, and the potential for bolstering seasonal prediction skill through targeted mitigation of these biases.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118982","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}
{"title":"Use of stepwise m5 model tree to forecast the P24max based on teleconnection indices","authors":"Golnar Ghanbarzadeh, Khalil Ghorbani, Meysam Salarijazi, Chooghi Bairam Komaki, Laleh Rezaei Ghaleh","doi":"10.1002/asl.1276","DOIUrl":"https://doi.org/10.1002/asl.1276","url":null,"abstract":"<p>In this study, the linear and non-linear multivariate relationships between 25 teleconnection indices (tele-indices) as independent variables and annual P24max as the dependent variable were analyzed using multivariate linear regression (MLR) and decision tree regression models (M5), in selected synoptic weather stations of Iran over a statistical period of 30 years (1992–2021). No strong and statistically significant correlation between each tele-index and P24max was observed. Therefore, it is not appropriate to attribute climate changes in the region to a single factor such as El Niño, but rather consider the combined influence of multiple factors. The M5 model demonstrated higher performance, indicating a non-linear relationship between tele-indices and P24max. The stepwise execution of the M5 model tree showed that the algorithm follows a greedy approach, and it is not necessary to use all variables to predict P24max. The normalized root mean square error (NRMSE) of P24max estimation was found to be 15%, 13%, 15%, 8%, 20%, 14%, and 12% with the coefficients of determination of 0.78, 0.79, 0.72, 0.85, 0.81, 0.82, and 0.84 in Hashemabad-Gorgan, Rasht, Kermanshah, Ahvaz, Bandar Abbas, Isfahan, and Birjand, respectively. Finally, it is possible to forecast P24max using tele-indices measured in the previous year.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1276","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143117900","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}
{"title":"The profound influence of the North Atlantic Ocean on Northeast Asia: A comprehensive multi-model study","authors":"Paul-Arthur Monerie, Buwen Dong, Weiwen Sun, Lixia Zhang","doi":"10.1002/asl.1280","DOIUrl":"https://doi.org/10.1002/asl.1280","url":null,"abstract":"<p>We assess the effects of the North Atlantic Sea surface temperature multidecadal variability on Northeast Asia using a set of sensitivity experiments (with a total of 530 ensemble members). We show that a warming of the North Atlantic Ocean leads to a strong and robust increase in temperature over Northeast Asia, which is replicated by a large majority of ensemble members. We show that the effect of the North Atlantic on Northeast Asia is model and season-dependent. We focus on two seasons, for which response to the North Atlantic Ocean is the most robust (autumn) and the less robust (spring) as indicated by the number of models that simulate a statistically significant change in surface air temperature. We use a clustering method to identify the sources of differences between models in simulating the effects of warming in the North Atlantic. We find that the primary mechanism linking the North Atlantic to Northeast Asia is a perturbation of the circumglobal teleconnection pattern (i.e., of the upper tropospheric atmospheric circulation), which allows modulation of the near-surface atmospheric circulation and an increase in temperature over East Asia. A second mechanism is related to the influence of the North Atlantic on the Pacific Ocean and the resulting effects on atmospheric circulation over Northeast Asia.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1280","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142759873","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}
{"title":"Interdecadal change in the relationship between the Antarctic oscillation and autumn rainfall in the Yunnan–Guizhou plateau of Southwest China","authors":"Yusen Li, Yong Zhao, Lixia Meng","doi":"10.1002/asl.1278","DOIUrl":"https://doi.org/10.1002/asl.1278","url":null,"abstract":"<p>The interdecadal change in the relationship between the Antarctic Oscillation (AAO) and autumn rainfall in the Yunnan–Guizhou Plateau of Southwest China is investigated by using the observed autumn rainfall data at 119 stations and the National Centers for Environment Prediction/National Center for Atmospheric Research reanalysis data for the period 1961–2021. Results show the AAO correlates well with the autumn rainfall in the Yunnan–Guizhou Plateau for the second period (2002–2021) because the AAO becomes stronger. The possible influencing mechanism of AAO on autumn rainfall in the Yunnan–Guizhou Plateau during 2002–2021 is related to the meridional teleconnection pattern and associated convection over the Philippine Sea. The positive AAO can trigger a meridional teleconnection pattern in the upper troposphere to propagate from the southern Pacific to northern Pacific and cause anomalous westerly over the tropical west Pacific, which inhibits the convection over the Philippine Sea. On the one hand, the weakened convection over the Philippine Sea causes the anomalous ascending motion over the Yunnan–Guizhou Plateau; on the other hand, it results in an anomalous anticyclone over the tropical Northwest Pacific and strengthens the transport of water vapor from the tropical Pacific to the Yunnan–Guizhou Plateau.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1278","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762270","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}
{"title":"Wildfire aerosols and their impact on weather: A case study of the August 2021 fires in Greece using the WRF-Chem model","authors":"Anastasios Rovithakis, Apostolos Voulgarakis","doi":"10.1002/asl.1267","DOIUrl":"https://doi.org/10.1002/asl.1267","url":null,"abstract":"<p>Wildfires are significant contributors to atmospheric gases and aerosols, impacting air quality and composition. This pollution from fires also affects radiative forcing, influencing short-term weather patterns and climate dynamics. Our research employs the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to investigate the repercussions of wildfires on aerosol abundances and associated immediate weather responses. We examine the summer season of 2021, a period marked by severe wildfire events in the country during a heatwave period. We conducted sensitivity experiments including and excluding wildfire emissions to measure their effects on aerosol optical depth (AOD), radiative forcing, and weather features such as temperature, humidity, clouds, and atmospheric circulation. Our findings demonstrate that the radiative impacts of wildfires negatively influence the local temperature over the fire smoke plume-affected areas. Conversely, neighbouring areas of continental Greece experience increases in temperature due to remote effects of wildfire emissions, caused by meteorological feedbacks that reduce atmospheric humidity. Crucially, including fire emissions significantly improves the simulated surface temperatures predicted by the model over the Greek domain. Our work demonstrates that wildfire-generated aerosols can significantly impact weather conditions and highlights the importance of including both local radiative effects and remote feedback for achieving more accurate weather prediction.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1267","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762112","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}
{"title":"Separating urban heat island circulation and convective cells through dynamic mode decomposition","authors":"Takuto Sato, Hideitsu Hino, Hiroyuki Kusaka","doi":"10.1002/asl.1279","DOIUrl":"https://doi.org/10.1002/asl.1279","url":null,"abstract":"<p>This study applies dynamic mode decomposition (DMD) to three-dimensional simulation results of urban heat island circulation (UHIC, which is horizontal circulation) and thermals (vertical convections). The aim of this study is to revisit how these phenomena coexist based on the characteristics of temporal changes in the flow field. We used DMD to obtain the dominant spatial patterns and information on temporal changes. One of the modes of horizontal wind, which does not change temporally (no oscillation or amplification), exhibits a spatial UHIC pattern. The unique feature of this UHIC mode is that there are small-scale striated structures (150–200 m) and large-scale convergence. The other modes are time-varying (oscillating and decaying) and represent smaller spatial-scale phenomena (150–250 m), such as thermals. The frequency of each mode takes various values, some of which are lower than the lifetime of thermals in accordance with the Deardorff convective scale (~10 min). These low-frequency modes showed striated structures similar to that observed in the UHIC modes. These results suggest that UHIC and thermals deform each other through components that vary in long temporal scales.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1279","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762700","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}
Nicky Stringer, Adam A. Scaife, Chris Bulmer, Paul Davies, Nick Dunstone, Margaret Gordon, Sarah Ineson, Jeff Knight, Joseph Mancell, Peter McLean, Doug Smith, Brent Walker, Christopher Walsh
{"title":"Predictability of European winter 2022/23","authors":"Nicky Stringer, Adam A. Scaife, Chris Bulmer, Paul Davies, Nick Dunstone, Margaret Gordon, Sarah Ineson, Jeff Knight, Joseph Mancell, Peter McLean, Doug Smith, Brent Walker, Christopher Walsh","doi":"10.1002/asl.1275","DOIUrl":"https://doi.org/10.1002/asl.1275","url":null,"abstract":"<p>The boreal winter of 2022/23 was notable as a third consecutive winter in which La Niña had an influence on the European weather. The GloSea6 seasonal forecast system predicted a blocked circulation pattern in the North Atlantic in early winter (December), and then a transition through mid-winter (January) into a more zonal pattern in late winter (February), consistent with the canonical La Niña teleconnection pattern seen previously. The seasonal forecast for the UK was an increased likelihood of near average temperatures, and drier- and calmer-than-average conditions. Both the predicted broad-scale circulation patterns and UK winter mean weather conditions verified well against observations, and we show that seasonal forecasts of the North Atlantic Oscillation (NAO) over the last 10 winters show similar skill to previously reported hindcasts. Throughout the winter, the Madden–Julian Oscillation (MJO) was particularly active. On three occasions, it exhibited strong phases 6 and 7. There was also a sudden stratospheric warming (SSW) that occurred on 16th February. This was followed by colder conditions and associated impacts similar to the canonical negative NAO response over the UK, although the main impact fell in March and so did not affect the winter (December–January–February) mean conditions.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1275","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762576","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}
{"title":"Sensitivity of simulated MJO to model vertical resolution in GAMIL3","authors":"He Wang, Lijuan Li, Bin Wang, Xiao Wang, Ye Pu","doi":"10.1002/asl.1277","DOIUrl":"https://doi.org/10.1002/asl.1277","url":null,"abstract":"<p>The impact of model vertical resolutions on simulation of the Madden–Julian Oscillation (MJO) was investigated using five AMIP simulations by the Grid-point Atmospheric Model of IAP LASG, version 3 (GAMIL3) with different vertical layers. Results showed that higher vertical resolutions produce a stronger and superior eastward propagation, coupled circulation–convection relationship, and MJO strength, as well as other convectively coupled equatorial waves when compared to the lowest vertical resolution. The improvements may be related to a better description of the tropical circulation in the higher vertical resolutions and model top, albeit without the significant improvement of MJO convection and stratospheric quasi-biennial oscillation in all simulations. Among the four tested high resolutions, the simulations with higher vertical resolutions from the surface to about 850 hPa produced better eastward propagation and larger total explained variance of the MJO, indicating the importance of the lower troposphere in simulating the MJO.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1277","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762677","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}
Svetlana Botsyun, Franziska Aemisegger, Leonie Villiger, Ingo Kirchner, Stephan Pfahl
{"title":"Quantifying free tropospheric moisture sources over the western tropical Atlantic with numerical water tracers and isotopes","authors":"Svetlana Botsyun, Franziska Aemisegger, Leonie Villiger, Ingo Kirchner, Stephan Pfahl","doi":"10.1002/asl.1274","DOIUrl":"https://doi.org/10.1002/asl.1274","url":null,"abstract":"<p>Tropical free-tropospheric humidity plays a crucial role for the Earth's radiative balance and climate sensitivity. In addition to atmospheric humidity, stable water isotopes can provide important information about the hydrological cycle. We use the isotope- and water tagging-enabled version of the COSMO<sub>iso</sub> model to determine isotopic fingerprints of diagnosed moisture pathways over the western tropical Atlantic (WTA). A convection-permitting, high-resolution (5 km) nudged simulation is performed for January–February 2020. During this period, the target region is characterized by alternating large-scale circulation regimes with different humidity and isotope signatures. Moist conditions in the middle troposphere (300–650 hPa) are associated with moisture transport from the south, east, southeast, as well as evaporation from the North Atlantic, while dry conditions correspond to extratropical transport from the north and west. To predict the contribution of different moisture sources, we used a statistical model based on the local specific humidity and temperature as predictors and obtained an <i>R</i>-squared (<i>R</i><sup>2</sup>) of 0.52. Adding water isotopes improved the prediction (<i>R</i><sup>2</sup> = 0.73), showing that isotopes provide unique information on moisture sources and transport patterns beyond conventional local observations.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 12","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1274","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142762358","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}