Atmospheric Science Letters最新文献

{"title":"The relationship among summer atmospheric boundary layer height over the Taklimakan Desert, its land surface parameters and Eurasian circulation","authors":"Minzhong Wang,&nbsp;Jiantao Zhang","doi":"10.1002/asl.1122","DOIUrl":"10.1002/asl.1122","url":null,"abstract":"<p>To investigate the relationship among summer atmospheric boundary layer (ABL) over the Taklimakan Desert (TD), its land surface parameters and large scale meteorological field, the Urumqi Institute of Desert Meteorology of China Meteorological Administration conducted a comprehensive observation of boundary layer in Tazhong, the hinterland of TD from July 1 to 31, 2016. The correlations between the ABL height and surface sensible heat, latent heat, air temperature, turbulent kinetic energy (TKE) and buoyancy term are analyzed by using the observed GPS sounding data, the surface layer micro meteorological data in the hinterland of the TD and ERA5 reanalysis data so as to study the correlation of the ABL height and Eurasian circulation field. The research results indicate: (1) The height of summer ABL over the TD does not fully correspond with the variation tendency of surface sensible heat flux. In addition to surface sensible heat, large scale advection and residual mixed layer (RML) are also crucial factor influencing ABL. (2) The surface TKE over the TD is consistent with ABL height variation, with the correlation coefficient of 0.62. Hence the equation of ABL height and TKE is expressed as: <i>Y</i> = 1609.2<i>X</i>⁴ – 12,828<i>X</i>³ + 35,617<i>X</i>² –39,514<i>X</i> + 15,858. (3) When the ABL height over the TD is quite high, 500 hPa altitude in Xinjiang is mostly controlled by anticyclone circulation, and the easterly low level jet (LLJ) tends to be formed at 850 hPa the next night. (4) The high correlation areas of summer ABL height over the TD and Eurasian temperature field are Xinjiang and Balkash Lake region. Significant positive correlation is identified between the ABL height and the temperature field at 850, 700, and 500 hPa of the above regions. The maximum correlation coefficient reaches 0.7. The study deepens the understanding of the relationship among the ABL process over the TD, land surface parameters and Eurasian circulation.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1122","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43963209","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":"Moisture sources tracking of a cold vortex rainstorm over Northeast China using FLEXPART","authors":"Yuting Yang,&nbsp;Xiaopeng Cui,&nbsp;Qiangli Zou","doi":"10.1002/asl.1123","DOIUrl":"10.1002/asl.1123","url":null,"abstract":"<p>Water vapor sources and related transport processes are fundamental to the understanding of precipitation mechanisms. This study focuses on a typical Northeast Cold Vortex (NECV) rainstorm on July 25, 2016, which brought floods and huge economic losses to Northeast China. Using the Lagrangian flexible particle dispersion model (FLEXPART) and the areal source–receptor attribution method, the moisture sources and transport characteristics during this event were analyzed. The results show that this NECV rainstorm occurred under a favorable atmospheric circulation background, and particles in the rainstorm area mainly came from the Indo-China Peninsula, South China Sea, Bay of Bengal, and central China at relatively low levels. The largest water vapor uptake and release were found in central China, which was the primary moisture source of this NECV precipitation. Although the Indian Subcontinent–Bay of Bengal–Indo-China Peninsula had a higher moisture intake than the South China Sea–the Philippines, a considerable amount of moisture in the former was released during transport, making the moisture contributions of the two equivalents. Furthermore, the Northeast rainstorm area had a non-negligible precipitation recycling process. All examined sources contributed more than 90% of the moisture in the rainstorm area.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 12","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1123","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47530717","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":"Towards a more comprehensive assessment of the intensity of historical European heat waves (1979–2019)","authors":"Florian N. Becker,&nbsp;Andreas H. Fink,&nbsp;Peter Bissolli,&nbsp;Joaquim G. Pinto","doi":"10.1002/asl.1120","DOIUrl":"10.1002/asl.1120","url":null,"abstract":"<p>Europe has been affected by record-breaking heat waves in recent decades. Using station data and a gridded reanalysis as input, four commonly used heat wave indices, the heat wave magnitude index daily (HWMId), excess heat factor (EHF), wet-bulb globe temperature (WBGT) and universal thermal climate index (UTCI), are computed. The extremeness of historical European heat waves between 1979 and 2019 using the four indices and different metrics is ranked. A normalisation to enable the comparison between the four indices is introduced. Additionally, a method to quantify the influence of the input parameters on heat wave magnitude is introduced. The spatio-temporal behaviour of heat waves is assessed by spatial–temporal tracking. The areal extent, large-scale intensity and duration are visualized using bubble plots. As expected, temperature explains the largest variance in all indices, but humidity is nearly as important in WBGT and wind speed plays a substantial role in UTCI. While the 2010 Russian heat wave is by far the most extreme event in duration and intensity in all normalized indices, the 2018 heat wave was comparable in size for EHF, WBGT and UTCI. Interestingly, the well-known 2003 central European heat wave was only the fifth and tenth strongest in cumulative intensity in WBGT and UTCI, respectively. The June and July 2019 heat waves were very intense, but short-lived, thus not belonging to the top heat waves in Europe when duration and areal extent are taken into account. Overall, the proposed normalized indices and the multi-metric assessment of large-scale heat waves allow for a more robust description of their extremeness and will be helpful to assess heat waves worldwide and in climate projections.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1120","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41613887","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 diurnal cycle of the lightning potential index over the Mexican tropical continental region during tropical cyclone Bud","authors":"Jorge Clouthier-Lopez,&nbsp;Ricardo Barrón-Fernández,&nbsp;David Alberto Salas-de-León","doi":"10.1002/asl.1119","DOIUrl":"10.1002/asl.1119","url":null,"abstract":"<p>Atmospheric processes over the Mexican continental territory can be influenced by the occurrence of tropical cyclones (TCs) over the adjacent oceans. Furthermore, the Mexican territory is characterized by the presence of diurnal cycles of lightning. The Lightning Potential Index (LPI), that is a measure of the potential for charge generation and separation that leads to lightning production in convective storms, was assessed for the diurnal variability of lightning that exhibited a strong diurnal cycle over the Mexican continental territory when TC Bud was over the adjacent eastern Pacific Ocean. The assessment, from 0000 UTC 10 June to 2000 UTC 15 June 2018, used the Weather Research and Forecasting (WRF) model with a new hybrid terrain-following sigma-pressure vertical coordinate. Two ensembles with various cumulus and microphysical parameterizations were performed with a grid spacing of 2 km. In one ensemble, sea surface temperature (SST) was prescribed from the Real-time global (RTG) SST analysis product and allowed to evolve interactively with the modeled atmosphere. Then, all the ensemble members were compared against available observations from the World Wide Lightning Location Network (WWLLN) to evaluate which model configurations perform best. It is not known if the LPI is capable of reproducing diurnal cycles of lightning over tropical regions; and the results allow gaining an understanding of the LPI when it reproduces the observed diurnal variability of lightning over land. The ensemble members that had better performances were those that included the prescribed SST.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1119","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42695758","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 role of atmospheric fronts in austral winter precipitation changes across Australia","authors":"Lindsay Lawrence,&nbsp;Rhys Parfitt,&nbsp;Caroline C. Ummenhofer","doi":"10.1002/asl.1117","DOIUrl":"10.1002/asl.1117","url":null,"abstract":"<p>Over the past few decades, Southeast Australia has experienced severe regional climatic events and some of the most extreme droughts on record, linked in part to influences from both the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). In this article, the extent to which austral winter rainfall anomalies, in years leading into co-occurring ENSO and IOD events, are communicated specifically through variations in atmospheric fronts is quantified. The most extreme wet (dry) conditions occur in winters characterized by sea surface temperature anomaly patterns exhibiting features of La Niña-Negative IOD (El Niño-Positive IOD). It is found that most of these precipitation anomalies are related to changes in the precipitation associated with the passing of atmospheric fronts specifically. Although there is some suggestion that there are accompanying changes in the frequency of atmospheric fronts, the response appears to be dominated by changes in the amount of precipitation per individual atmospheric front. In addition, the distribution in the dynamic strength of individual atmospheric fronts remains relatively unchanged.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1117","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43895345","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":"Long-term changes in spatially coherent extreme precipitation systems over Central India","authors":"Anu Gupta,&nbsp;Hiroshi G. Takahashi","doi":"10.1002/asl.1118","DOIUrl":"10.1002/asl.1118","url":null,"abstract":"<p>The present study examined extreme rainfall events (EREs) in central India during the summer monsoon season, focusing on their spatial characteristics. A station-based gridded and a station-satellite-blended dataset was used to examine long-term and recent variations in precipitation characteristics for 50 years (1951–2000) and 38 years (1981–2018), respectively. A precipitation system approach (PSA) was applied to identify the ERE precipitation systems and categorized spatial sizes of ERE systems into three categories: sporadic, intermediate, and massive ERE precipitation systems. Conventionally, the ERE frequency is equal to the total number of ERE grids, whereas PSA counts ERE systems. The sporadic precipitation grid contributes 42% of all the ERE grids, and sporadic EREs frequency increases in the long-term. The long-term trend of intermediate and massive EREs does not increase and quite sharply increases, respectively, and these EREs are also intensifying. Recent 38 years have shown a reverse in the trends of ERE characteristics, the frequency and intensity of intermediate and massive EREs have decreased, whereas the massive ERE systems are broadening.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 11","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1118","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42133709","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 the shortwave and longwave components of greenhouse gas radiative forcing","authors":"Keith P. Shine,&nbsp;Rachael E. Byrom,&nbsp;Ramiro Checa-Garcia","doi":"10.1002/asl.1116","DOIUrl":"10.1002/asl.1116","url":null,"abstract":"<p>Many important greenhouse gases (including water vapour, carbon dioxide, methane and ozone) absorb solar radiation. When gas concentrations change, this absorption exerts a radiative forcing that modifies the thermal infrared (‘longwave’) radiative forcing which is predominant for most gases (ozone being a major exception). The nature of the solar forcing differs from the longwave forcing in several ways. For example, the sign of the instantaneous solar forcing can differ between the tropopause and top-of-atmosphere, and the sign can differ between gases. In addition, a significant part of the solar forcing can be manifested in the longwave, following stratospheric temperature adjustment, which can counteract or enhance the instantaneous solar forcing. Here the nature of solar forcing is examined via a mixture of idealised and more realistic calculations, which consider the effect of perturbations in carbon dioxide, methane and ozone. An apparent contradiction in the sign of the solar forcing of carbon dioxide is resolved; it is shown to be negative, reducing the net carbon dioxide forcing by about 2.3%. The relevance of this work to the effective radiative forcing concept is also discussed.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1116","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49643915","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":"A new subseasonal atmospheric teleconnection bridging tropical deep convection over the western North Pacific and Antarctic weather","authors":"Yuexiang Sun,&nbsp;Benkui Tan","doi":"10.1002/asl.1115","DOIUrl":"10.1002/asl.1115","url":null,"abstract":"<p>Previous studies indicate that convective heating variability of the western North Pacific summer monsoon (WNPSM) influences strongly weather and climate over East Asia. Based on daily reanalysis data and interpolated outgoing longwave radiation (OLR) data, this study demonstrates that the WNPSM convection can also cause severe weather events remotely over the Antarctic through the exciting of the Australia-South Pacific-Atlantic wave train (ASPA pattern). Surface air temperature (SAT) rises over the Ross Sea-Mawson-Dumont d'Urville Seas sector and over the Weddell Sea, while the SAT drops over the Amundsen–Bellingshausen Seas. Concurrently, sea ice concentration (SIC) is reduced over the Ross Sea and enhanced over the Amundsen–Bellingshausen Seas. The result suggests that the newly found ASPA pattern may serve as an important bridge linking the WNPSM convection and the weather over the Antarctic region.</p><p>The dynamics of ASPA's formation and propagation are also investigated comprehensively. Day-to-day energy budget analysis suggests that after its initiation by WNPSM convection, the ASPA pattern is driven by the baroclinic energy conversion from the climatological flow and nonlinear term. The barotropic energy conversion from the climatological flow contributes to positive KE tendency before day +1 and negative KE tendency after day +1. It is therefore extremely important to improve the representations of the climatological-mean sea ice and jet stream, wave-mean flow interaction and wave-wave interaction in the mid- and high-latitudes of the Southern Hemisphere, as well as the convection over the WNPSM region of the Northern Hemisphere in numerical model for a better weather prediction for the Antarctic.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1115","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48416619","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":"Characteristics of newly formed mesoscale convective systems during the abnormal precipitation over the Yangtze River basin from June to July, 2020","authors":"Xiuping Yao,&nbsp;Honghua Zhang,&nbsp;Jiali Ma,&nbsp;Dawei Shi,&nbsp;Weijian Wang,&nbsp;Guichen Wang","doi":"10.1002/asl.1114","DOIUrl":"10.1002/asl.1114","url":null,"abstract":"<p>A 62-day “extremely violent Meiyu” occurred in the Yangtze River basin from June to July in 2020, and its abnormal precipitation caused serious losses to the social economy. In this paper, the characteristics of newly formed mesoscale convective systems (MCSs) and the environmental conditions affecting the MCS formation during this abnormal precipitation event are investigated based on hourly datasets, including the temperature of brightness blackbody (<i>T</i>_BB) data derived from the FY-2F geostationary meteorological satellite, and the three-source merged precipitation products from China Meteorological Administration. The results show that there were 31,778 times of short-duration heavy precipitation (hourly precipitation exceeding 20 mm) occurred in the Yangtze River basin from June to July in 2020. The 69.3% of short-duration heavy precipitation (hourly precipitation exceeding 20 mm) are closely related to the MCSs. The increase of newly formed MCSs leaded to more short-duration heavy precipitation. The abnormal precipitation in the Yangtze River basin from June to July is mainly caused by elongated MCSs with an average lifetime of 6 h. The number of the newly formed MCSs presents obvious diurnal variations, with the most frequent at 20:00 (Beijing Time, the same below). The newly formed MCSs are prone to appear near the Yangtze–Huaihe shear line, and the magnitude of southerly wind at 500 hPa determines the distance between the MCSs and the shear line. The enhancement of vorticity advection at 500 hPa and water vapor convergence are conducive to the MCS formation. The weakening of low-level jet corresponds to the increase of newborn MCS.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1114","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42204708","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":"Impact of aerosol concentration on elevation-dependent warming pattern in the mountains of Nepal","authors":"Yam Prasad Dhital,&nbsp;Jianwu Tang,&nbsp;Ashok Kumar Pokharel,&nbsp;Qiuhong Tang,&nbsp;Mukesh Rai","doi":"10.1002/asl.1101","DOIUrl":"10.1002/asl.1101","url":null,"abstract":"<p>Greater warming rates in the mountain areas (higher elevations) compared to other parts of the world have drawn the attention of the scientific community in recent years. In this study, we first analyzed elevation-dependent warming (EDW) patterns based on maximum temperature trends along the south–north temperature gradients of Nepal and then focused on influencing factors of EDW. Nonparametric statistical test was used to identify the warming trend (1970–2016) in each meteorological station along the altitude gradients. Furthermore, aerosol optical depth data was used to observe aerosol concentrations in different seasons across Nepal. Overall, the EDW trend was found positive on the mean annual and seasonal cycle in the study area. It was observed that there was more significant positive correlation of warming rates with altitude below the middle parts of the Lower Hills while a less pronounced correlation above it. This different behavior is attributed to high aerosol concentration on the lower part of this region.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"23 10","pages":""},"PeriodicalIF":3.0,"publicationDate":"2022-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://rmets.onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1101","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45857613","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}