期刊文献+
共找到1,407篇文章
< 1 2 71 >
每页显示 20 50 100
An Extreme Monsoonal Heavy Rainfall Event over Inland South China in June 2022: A Synoptic Causes Analysis 被引量:1
1
作者 邓文剑 任鹏飞 +2 位作者 张东 孙宇 吴乃庚 《Journal of Tropical Meteorology》 SCIE 2023年第1期16-25,共10页
An extreme monsoonal heavy rainfall event lasted for nine days and recurred in the interior of northern south China from June 13 to 21, 2022. Using regional meteorological stations and ERA5 reanalysis data, the causes... An extreme monsoonal heavy rainfall event lasted for nine days and recurred in the interior of northern south China from June 13 to 21, 2022. Using regional meteorological stations and ERA5 reanalysis data, the causes of this extreme monsoonal rainfall event in south China were analyzed and diagnosed. The results are shown as follows. A dominant South Asian high tended to be stable near the Qinghai-Tibet Plateau, providing favorable upper-level dispersion conditions for the occurrence of heavy rainfall in south China. A western Pacific subtropical high dominated the eastern part of the South China Sea, favoring stronger and more northward transport of water vapor to the northern part of south China at lower latitudes than normal. The continuous heavy precipitation event can be divided into two stages. The first stage(June 13-15) was the frontal heavy rainfall caused by cold air(brought by an East Asian trough)from the mid-latitudes that converged with a monsoonal airflow. The heavy rains occurred mostly in the area near a shear in front of the center of a synoptic-system-related low-level jet(SLLJ), and the jet stream and precipitation were strongest in the daytime. The second stage(June 16-21) was the warm-sector heavy rainfall caused by a South China Sea monsoonal low-level jet penetrating inland. The heavy rainfall occurred on the windward slope of the Nanling Mountains and in the northern part of a boundary layer jet(BLJ). The BLJ experienced five nighttime enhancements, corresponding well with the enhancement of the rainfall center, showing significant nighttime heavy rainfall characteristics. Finally, a conceptual diagram of inland-type warm-sector heavy rainfall in south China is summarized. 展开更多
关键词 monsoonal heavy rainfall south China low-level jet synoptic causes
下载PDF
Low-Level Temperature Inversions and Their Effect on Aerosol Condensation Nuclei Concentrations under Different Large-Scale Synoptic Circulations 被引量:15
2
作者 LI Jun CHEN Hongbin +3 位作者 Zhanqing LI WANG Pucai Maureen CRIBB FAN Xuehua 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2015年第7期898-908,共11页
Knowledge of the statistical characteristics of inversions and their effects on aerosols under different large-scale synoptic circulations is important for studying and modeling the diffusion of pollutants in the boun... Knowledge of the statistical characteristics of inversions and their effects on aerosols under different large-scale synoptic circulations is important for studying and modeling the diffusion of pollutants in the boundary layer. Based on results gen- erated using the self-organizing map (SOM) weather classification method, this study compares the statistical characteristics of surface-based inversions (SBIs) and elevated inversions (EIs), and quantitatively evaluates the effect of SBIs on aerosol condensation nuclei (CN) concentrations and the relationship between temperature gradients and aerosols for six prevailing synoptic patterns over the the Southern Great Plains (SGP) site during 2001-10. Large-scale synoptic patterns strongly influ- ence the statistical characteristics of inversions and the accumulation of aerosols in the low-level atmosphere. The activity, frequency, intensity, and vertical distribution of inversions are significantly different among these synoptic patterns. The verti- cal distribution of inversions varies diurnally and is significantly different among the different synoptic patterns. Anticyclonic patterns affect the accumulation of aerosols near the ground more strongly than cyclonic patterns. Mean aerosol CN con- centrations increase during SBIs compared to no inversion cases by 16.1%, 22.6%, 24.5%, 58.7%, 29.8% and 23.7% for the six synoptic patterns. This study confirms that there is a positive correlation between temperature gradients and aerosol CN concentrations near the ground at night under similar large-scale synoptic patterns. The relationship is different for different synoptic patterns and can be described by linear functions. These findings suggest that large-scale synoptic patterns change the static stability of the atmosphere and inversions in the lower atmosphere, thereby influencing the diffusion of aerosols near the ground. 展开更多
关键词 temperature inversion AEROSOL condensation nuclei large-scale synoptic pattern statistical characteristics
下载PDF
Observation of Low-Level Jets in the Eastern Tropical Indian Ocean Based on Shipborne Coherent Doppler Lidar
3
作者 WANG Haiyuan LIU Lin +10 位作者 FAN Mengqi YANG Yang YANG Guang DUAN Yongliang LIU Baochao SU Qinglei ZHANG Binbin WANG Fengjun SHI Xuliang LI Qiuchi ZENG Ai 《Journal of Ocean University of China》 SCIE CAS CSCD 2024年第5期1163-1172,共10页
In contrast to the Pacific and Atlantic Oceans,the Indian Ocean has lacked in-situ observations of wind profiles over open sea areas for decades.In 2021,a shipborne coherent Doppler lidar(CDL)was used to observe in-si... In contrast to the Pacific and Atlantic Oceans,the Indian Ocean has lacked in-situ observations of wind profiles over open sea areas for decades.In 2021,a shipborne coherent Doppler lidar(CDL)was used to observe in-situ wind profiles in the eastern tropical Indian Ocean.This equipment successfully captured low-level jets(LLJs)in the region,and their characteristics were thoroughly analyzed.Results reveal that the observed wind speed of LLJs in the eastern Indian Ocean ranges from 6 m s^(-1) to 10 m s^(-1) during the boreal winter and spring seasons,showing a height range of 0.6 to 1 km and two peak times at 0800 and 2000 UTC.This wind shear is weaker than that in land or offshore areas,ranging from 0 s^(-1) to 0.006 s^(-1).Moreover,the accuracy of the CDL data is compared to that of ERA5 data in the study area.The results indicate that the zonal wind from ERA5 data significantly deviated from the CDL measurement data,and the overall ERA5 data are substantially weaker than the in-situ observations.Notably,ERA5 underestimates northwestward LLJs. 展开更多
关键词 low-level jets coherent Doppler lidar ERA5 RADIOSONDE eastern Indian Ocean
下载PDF
Synoptic-scale reversal of dipole surface temperature anomalies over East Asia and Central Siberia in November 2021
4
作者 Yan Kong Xinping Xu Botao Zhou 《Atmospheric and Oceanic Science Letters》 CSCD 2023年第3期33-38,共6页
2021年11月,东亚与中西伯利亚经历了相反的冷暖异常转换,表现为“中西伯利亚偏冷,东亚偏暖”与“中西伯利亚偏暖,东亚偏冷”的交替出现.该偶极型气温异常的天气尺度反转伴随着大尺度大气环流异常的反转.进一步分析表明,东亚与中西伯利... 2021年11月,东亚与中西伯利亚经历了相反的冷暖异常转换,表现为“中西伯利亚偏冷,东亚偏暖”与“中西伯利亚偏暖,东亚偏冷”的交替出现.该偶极型气温异常的天气尺度反转伴随着大尺度大气环流异常的反转.进一步分析表明,东亚与中西伯利亚的偶极型气温异常反转是1979-2021年期间11月欧亚气温日变化的主导模态之一(发生概率超过56%). 展开更多
关键词 天气尺度反转 偶极型气温异常 东亚-中西伯利亚 大尺度环流
下载PDF
Synoptic Verification of Precipitation Forecast of Three NWP Models from May to August of 2008 in Liaoning Province 被引量:5
5
作者 崔锦 周小珊 +1 位作者 陈力强 张爱忠 《Meteorological and Environmental Research》 CAS 2010年第8期7-11,20,共6页
In order to evaluate the precipitation forecast performance of mesoscale numerical model in Northeast China,mesoscale model in Liaoning Province and T213 model,and improve the ability to use their forecast products fo... In order to evaluate the precipitation forecast performance of mesoscale numerical model in Northeast China,mesoscale model in Liaoning Province and T213 model,and improve the ability to use their forecast products for forecasters,the synoptic verifications of their 12 h accumulated precipitation forecasts of 3 numerical modes from May to August in 2008 were made on the basis of different systems impacting weather in Liaoning Province.The time limitations were 24,36,48 and 60 h.The verified contents included 6 aspects such as intensity and position of precipitation center,intensity,location,scope and moving velocity of precipitation main body.The results showed that the three models had good forecasting capability for precipitation in Liaoning Province,but the cupacity of each model was obviously different. 展开更多
关键词 Numerical model Precipitation forecast synoptic meteorology verification China
下载PDF
Analysis on A Synoptic Process of Freezing Rain in Anshan City
6
作者 韩艳凤 何军 陈晓岩 《Meteorological and Environmental Research》 CAS 2010年第11期20-22,共3页
Based on MICAPS(Meteorological Information Combine Analysis and Process System) and observational data in Anshan Observatory,the freezing rain event occurred rarely in Anshan on February 24 in 2010 was analyzed.The re... Based on MICAPS(Meteorological Information Combine Analysis and Process System) and observational data in Anshan Observatory,the freezing rain event occurred rarely in Anshan on February 24 in 2010 was analyzed.The results showed that there existed the inversion layer from the ground to 850 hpa level even to 700 hPa level when the local surface temperature was below 0 ℃.The temperature stratification structure of coldness-warmth-coldness was prevailing from the upper level to the ground with the existence of the ice melting layer of a certain thickness.Thus the freezing event occurred in Anshan. 展开更多
关键词 Cold air Freezing rain low-level jet stream Temperature inversion China
下载PDF
Local Meteorological and Synoptic Characteristics of Fogs Formed over Incheon International Airport in the West Coast of Korea 被引量:4
7
作者 Chang Ki KIM Seong Soo YUM 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第4期761-776,共16页
Fogs observed over Incheon international airport (IIA) in the west coast of Korea from January 2002 to August 2006 are classified into categories of coastal fog, cold sea fog, and warm sea fog based on the areal ext... Fogs observed over Incheon international airport (IIA) in the west coast of Korea from January 2002 to August 2006 are classified into categories of coastal fog, cold sea fog, and warm sea fog based on the areal extent of the fogs and the difference between the air temperature (T ) and the SST, i.e., cold sea fog if TSST = T -SST 〉 0~0C and warm sea fog if TSST 〈 0~0C. The numbers of coastal, cold, and warm sea fog cases are 64, 26, and 9. Coastal fogs form most frequently in winter, while cold sea fogs occur mostly in summer and warm sea fogs are observed from January to May but not in November and December. On average the air gets colder by 1.6~0C during the three hours leading up to the coastal fog formation, and an additional cooling of 1.1~0C occurs during the fog. The change in the dew point temperature (T_d) is minimal except during the fog (0.6~0C). Decreases in T for the cold and warm sea fogs are relatively smaller. The average Td is higher than SST during the cold sea fog periods but this T_d is more than 4~0C higher than that for the corresponding non-fog days, suggesting that cold sea fogs be formed by the cooling of already humid air (i.e., T_d〉SST). Increases of T_d are significant during the warm sea fog periods (1.4~0C), implying that effcient moisture supply is essential to warm sea fog formation. Four major synoptic patterns are identified in association with the observed fogs. The most frequent is a north Pacific high that accounts for 38% of cases. Surface or upper inversions are present in 77%, 69%, and 81% of the fog periods for coastal, cold, and warm sea fogs, respectively. 展开更多
关键词 costal fogs sea fogs west coast of Korea meteorological and synoptic characteristics
下载PDF
Using Synoptic Classification and Trajectory Analysis to Assess Air Quality during the Winter Heating Period in rümqi, China 被引量:4
8
作者 WANG Lili WANG Yuesi +1 位作者 SUN Yang LI Yuanyuan 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第2期307-319,共13页
Synoptic patterns identified by an automated procedure employing principal- component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine ... Synoptic patterns identified by an automated procedure employing principal- component analysis and a two-stage cluster analysis, and backward trajectory analysis clustered by the HYSPLIT4.9 model were used to examine air quality patterns over¨ Uru¨mqi, China, one of the most heavily polluted cities in the world. Six synoptic patterns representing different atmospheric circulation patterns and air-mass characteristics were classified during the winter heating periods from 2001 to 2008, and seven trajectory clusters representing different paths of air masses arriving at ürümqi were calculated during the winter heating periods from 2005 to 2008. Then air quality was evaluated using these two approaches, and significant variations were found across both synoptic patterns and trajectory clusters. The heaviest air-pollution episodes occurred when ürümqi was either in an extremely cold, strong anticyclone or at the front of a migrating cyclone. Both conditions were characterized by with light winds, cold, wet surface air, and relatively dry upper air. ürümqi was predominately influenced by air masses from the southwest and from local areas. Air pollution index (API) levels were highest for air masses originating from the southwest with a longer path or for the local area, because of transport from semi-desert/desert regions by strong winds and because of local heavy pollution emissions, respectively. The interactions between these two analytical approaches showed that poor diffusion conditions, together with local circulation, enhanced air pollution, besides, regional air-mass transport caused by strong winds contributed to serious air quality under relatively good diffusion conditions. 展开更多
关键词 synoptic climatology backward trajectory automated meteorological classification air pollu- tion index (API) ürümqi
下载PDF
Simulations of the Motion of Tropical Cyclone-like Vortices in the Presence of Synoptic and Mesoscale Circulations 被引量:3
9
作者 罗哲贤 平凡 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第3期519-528,共10页
Initial mesoscale vortex effects on the tropical cyclone (TC) motion in a system where three components coexist (i.e., an environmental vortex (EV), a TC, and mesoscale vortices) were examined using a barotropic... Initial mesoscale vortex effects on the tropical cyclone (TC) motion in a system where three components coexist (i.e., an environmental vortex (EV), a TC, and mesoscale vortices) were examined using a barotropic vorticity equation model with initial fields where mesoscale vortices were generated stochastically. Results of these simulations indicate that the deflection of the TC track derived from the initial mesoscale vortices was clearly smaller than that from the beta effect in 60% of the cases. However, they may have a more significant impact on the TC track under the following circumstances. First, the interaction between an adjacent mesoscale vortex and the TC causes the emergence of a complicated structure with two centers in the TC inner region. This configuration may last for 8 h, and the two centers undergo a cyclonic rotation to make the change in direction of the TC motion. Second, two mesoscale vortices located in the EV circulation may merge, and the merged vortex shifts into the EV inner region, intensifying both the EV and steering flow for the TC, increasing speed of the TC. 展开更多
关键词 cyclone-like vortices synoptic and mesoscale circulations
下载PDF
The spring Yellow Sea fog:synoptic and air–sea characteristics associated with different airflow paths 被引量:2
10
作者 HUANG Jian WANG Bin +3 位作者 WANG Xin HUANG Fei LU Weihua Tu Jing 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2018年第1期20-29,共10页
The fog occurs frequently over the Yellow Sea in spring(April–May), a climatical period of Asian monsoon transition. A comprehensive survey of the characteristic weather pattern and the air-sea condition is provide... The fog occurs frequently over the Yellow Sea in spring(April–May), a climatical period of Asian monsoon transition. A comprehensive survey of the characteristic weather pattern and the air-sea condition is provided associated with the fog for the period of 1960–2006. The sea fog is categorized by airflow pathways of backward trajectory cluster analysis with the surface observations derived from international comprehensive oceanatmosphere dataset(I_COADS) I_COADS datasets and contemporaneous wind fields from the National Centers for Environmental Prediction(NCEP)/National Center for Atmospheric Research(NCAR) reanalysis. On the basis of the airflow paths, the large-scale lower-tropospheric circulation patterns and the associated surface divergence,the distribution of a vertical humidity, the horizontal water vapor transportation and the air-sea temperature difference are investigated and the major findings are summarized as follows.(1) Four primary clusters of the airflow paths that lead to spring sea fog formation are identified. They are originated from the northwest, east,southeast and southwest of the Yellow Sea, respectively.(2) Springtime Yellow Sea fog occurs under two typical weather patterns: the Yellow Sea high(YSH) and cyclone and anticyclone couplet(CAC). Each pattern appears by about equal chance in April but the YSH occurrence drops to around one third and the CAC rises to around two third of chance in May.(3) The common feature in the two types of synoptic conditions is that surface divergence center is located over the Yellow Sea.(4) For the YSH type of fog, water vapor comes mainly from local evaporation with a well-defined dry layer present in the lower atmosphere; for the CAC type of fog, however, water vapor comes mainly from areas outside the Yellow Sea with a thick surface layer of high humidity.(5) With the differences in weather patterns and its associated vertical distribution of the humidity and the transportation of water vapor, there are two types of sea fogs. Most fogs of the CAC types are "warm" fog, while fogs of YSH type have nearly equal chance to be "warm" and "cold" fog. 展开更多
关键词 springtime sea fog Yellow Sea airflow clusters synoptic patterns characteristics of sea fog
下载PDF
Roles of Synoptic to Quasi-Monthly Disturbances in Generating Two Pre-Summer Heavy Rainfall Episodes over South China 被引量:2
11
作者 Zhina JIANG Da-Lin ZHANG Hongbo LIU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2020年第2期211-228,共18页
In this study,power spectral analysis and bandpass filtering of daily meteorological fields are performed to explore the roles of synoptic to quasi-monthly disturbances in influencing the generation of pre-summer heav... In this study,power spectral analysis and bandpass filtering of daily meteorological fields are performed to explore the roles of synoptic to quasi-monthly disturbances in influencing the generation of pre-summer heavy rainfall over South China.Two heavy rainfall episodes are selected during the months of April-June 2008-15,which represent the collaboration between the synoptic and quasi-biweekly disturbances and the synoptic and quasi-monthly disturbances,respectively.Results show that the first heavy rainfall episode takes place in a southwesterly anomalous flow associated with an anticyclonic anomaly over the South China Sea(SCS)at the quasi-biweekly scale with 15.1%variance contributions,and at the synoptic scale in a convergence zone between southwesterly and northeasterly anomalous flows associated with a southeastward-moving anticyclonic anomaly on the leeside of the Yungui Plateau and an eastwardpropagating anticyclonic anomaly from higher latitudes with 35.2%variance contribution.In contrast,the second heavy rainfall episode takes place in southwest-to-westerly anomalies converging with northwest-to-westerly anomalies at the quasi-monthly scale with 23.2%variance contributions to the total rainfall variance,which are associated with an anticyclonic anomaly over the SCS and an eastward-propagating cyclonic anomaly over North China,respectively.At the synoptic scale,it occurs in south-to-southwesterly anomalies converging with a cyclonic anomaly on the downstream of the Yungui Plateau with 49.3%variance contributions.In both cases,the lower-tropospheric mean south-to-southwesterly flows provide ample moisture supply and potentially unstable conditions;it is the above synoptic,quasi-biweekly or quasimonthly disturbances that determine the general period and distribution of persistent heavy rainfall over South China. 展开更多
关键词 synoptic scale pre-summer rainfall quasi-biweekly scale quasi-monthly disturbances
下载PDF
Impact of Interannual Variation of Synoptic Disturbances on the Tracks and Landfalls of Tropical Cyclones over theWestern North Pacific 被引量:1
12
作者 Xingyan ZHOU Riyu LU Guanghua CHEN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第12期1469-1477,共9页
This study investigates the tropical cyclone(TC)activity associated with the two leading modes of interannual variability in synoptic disturbances.Both leading modes are found to be related to a dipole pattern of TC o... This study investigates the tropical cyclone(TC)activity associated with the two leading modes of interannual variability in synoptic disturbances.Both leading modes are found to be related to a dipole pattern of TC occurrence between the subtropical western North Pacific and the South China Sea.Therefore,in this study we performed composite analyses on TC tracks and landfalls,based on the cases of combined modes,to highlight the differences.The composite results indicate that these cases are characterized by distinct features of TC tracks and landfalls:more TCs tend to take recurving tracks and attack eastern China,Korea and Japan,or more TCs exhibit straight-moving tracks and hit the Philippines,Vietnam and southern China.Further analyses suggest that these distinctions in the TC prevailing tracks and landfalls can be attributed to the differences in large-scale steering flow and TC genesis location. 展开更多
关键词 tropical CYCLONE LANDFALL track INTERANNUAL variability synoptic disturbance
下载PDF
EFFECT OF TROPICAL CYCLONE PRECIPITATION ON ALLEVIATING THE DROUGHT SITUATION IN THE SOUTHEAST COASTAL REGIONS OF CHINA DURING SUMMER AND AUTUMN:USING THE IMPROVED OBJECTIVE SYNOPTIC ANALYSIS TECHNIQUE 被引量:1
13
作者 蒋昱鑫 李嘉鹏 王元 《Journal of Tropical Meteorology》 SCIE 2016年第3期277-286,共10页
To quantitatively study the role of tropical cyclone precipitation(TCP) on alleviating the drought in the southeast coastal region of China(SCR) during summer and autumn,the objective synoptic analysis technique(OSAT)... To quantitatively study the role of tropical cyclone precipitation(TCP) on alleviating the drought in the southeast coastal region of China(SCR) during summer and autumn,the objective synoptic analysis technique(OSAT),improved for consistency and rationality,was used to separate the TCP data on the summers and autumns of 1963-2005 on the basis of daily precipitation data from stations and tropical cyclone best track data.After defining the season drought index,the actual drought distribution and the assumed drought distribution without TCP were acquired.The results showed that within 1 000 km from the southeast coastline of China,TCP accounted for 11.3%of natural precipitation(NP).Without TCP,the drought index in the SCR during summer would have increased from 0.2 to 0.6 or even above 1.0 in some regions whereas the drought index during autumn would have increased from 0.4 to 0.6 or above 1.2 in some regions.The impact of TCP on drought decreases progressively from the southeast coastline to the inland regions.The TCP proportion(TCPP) showed a significant negative correlation with the drought index in many regions of the southeast,and the significant region is wider in autumn than in summer.TCP relieved the drought most significantly within a range of 0-500 km from the southeast coastline.This drought relief showed different characteristics for the interannual variability in summer and autumn,and the cross wavelet transform indicated that the impact of TCP on drought mainly lies in 2-4-year time scales.In particular,there was a significant effect during the summers of 1977-1985 and in the autumns following that of 1985.Therefore,TCP has indeed largely alleviated drought in the SCR during summer and autumn. 展开更多
关键词 TROPICAL CYCLONE precipitation DROUGHT objective synoptic analysis TECHNIQUE
下载PDF
Characteristics of Sea Breeze Front Development with Various Synoptic Conditions and Its Impact on Lower Troposphere Ozone Formation 被引量:1
14
作者 Hyo-Eun JI Soon-Hwan LEE Hwa-Woon LEE 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第5期1461-1478,共18页
To examine the correlation between the sizes of sea breeze fronts and pollutants under the influence of synoptic fields, a numerical simulation was conducted in the southeast coastal area of the Korean Peninsula, wher... To examine the correlation between the sizes of sea breeze fronts and pollutants under the influence of synoptic fields, a numerical simulation was conducted in the southeast coastal area of the Korean Peninsula, where relatively high concentrations of pollutants occur because of the presence of various kinds of industrial developments. Sea breeze and sea breeze front days during the period 2005 09 were identified using wind profiler data and, according to the results, the number of days were 72 and 53, respectively. When synoptic forcing was weak, sea breeze fronts moved fast both in horizontal fields and in terms of wind velocity, while in the case of strong synoptic forcing, sea breeze fronts remained at the coast or moved slowly due to strong opposing flows. In this case, the sea breeze front development function and horizontal potential temperature difference were larger than with weak synoptic forcing. The ozone concentration that moves together with sea breeze fronts was also formed along the frontal surfaces. Ozone advection and diffusion in the case of strong synoptic forcing was suppressed at the frontal surface and the concentration gradient was large. The vertical distribution of ozone was very low due to the Thermal Internal Boundary Layer (TIBL) being low. 展开更多
关键词 sea breeze front synoptic opposing flow wind profiler OZONE numerical simulation
下载PDF
Interannual Variations in Synoptic-Scale Disturbances over the Western North Pacific 被引量:1
15
作者 Xingyan ZHOU Riyu LU +1 位作者 Guanghua CHEN Liang WU 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2018年第5期507-517,共11页
The present study investigates the interannual variation of June-November synoptic disturbance activity over the western North Pacific(WNP) and its relationship with large-scale circulation for the period 1958-2014.... The present study investigates the interannual variation of June-November synoptic disturbance activity over the western North Pacific(WNP) and its relationship with large-scale circulation for the period 1958-2014. Two leading modes of eddy kinetic energy for the disturbance variability over the WNP are obtained by EOF analysis, characterized by anomalous eddy kinetic energy over the subtropical WNP and around the Philippines, respectively. These modes explain a large portion of the interannual variance of synoptic disturbance activity over the WNP. Both are associated with lower-level cyclonic anomalies, but with different locations: over the subtropical WNP for the first mode and over the South China Sea for the second mode. Considering the impact of ENSO on synoptic disturbance activity over the WNP, we repeat the analyses after removing the effect of ENSO, which is simply defined as the components linearly regressed onto the Ni o3.4 index, and find similar results, suggesting that the leading modes and their relationships with large-scale circulation exist without SST effects.Further analyses suggest that the meridional shear of zonal winds caused by cyclonic anomalies is crucial for maintaining the leading modes through barotropic conversion. 展开更多
关键词 synoptic disturbance activity interannual variability leading mode barotropic conversion
下载PDF
Impacts of Aerosol−Radiation Interactions on the Wintertime Particulate Pollution under Different Synoptic Patterns in the Guanzhong Basin,China 被引量:2
16
作者 Naifang BEI Xia LI +6 位作者 Qiyuan WANG Suixin LIU Jiarui WU Jiayi LIANG Lang LIU Ruonan WANG Guohui LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第7期1141-1152,共12页
The effects of aerosol-radiation interactions(ARI)are not only important for regional and global climate,but they can also drive particulate matter(PM)pollution.In this study,the ARI contribution to the near-surface f... The effects of aerosol-radiation interactions(ARI)are not only important for regional and global climate,but they can also drive particulate matter(PM)pollution.In this study,the ARI contribution to the near-surface fine PM(PM_(2.5))concentrations in the Guanzhong Basin(GZB)is evaluated under four unfavorable synoptic patterns,including“northlow”,“transition”,“southeast-trough”,and“inland-high”,based on WRF-Chem model simulations of a persistent heavy PM pollution episode in January 2019.Simulations show that ARI consistently decreases both solar radiation reaching down to the surface(SWDOWN)and surface temperature(TSFC),which then reduces wind speed,induces sinking motion,and influences cloud formation in the GZB.However,large differences under the four synoptic patterns still exist.The average reductions of SWDOWN and daytime TSFC in the GZB range from 15.2%and 1.04°C in the case of the“transition”pattern to 26.7%and 1.69°C in the case of the“north-low”pattern,respectively.Furthermore,ARI suppresses the development of the planetary boundary layer(PBL),with the decrease of PBL height(PBLH)varying from 18.7%in the case of the“transition”pattern to 32.0%in the case of the“north-low”pattern.The increase of daytime near-surface PM_(2.5)in the GZB due to ARI is 12.0%,8.1%,9.5%,and 9.7%under the four synoptic patterns,respectively.Ensemble analyses also reveal that when near-surface PM_(2.5)concentrations are low,ARI tends to lower PM_(2.5)concentrations with decreased PBLH,which is caused by enhanced divergence or a transition from divergence to convergence in an area.ARI contributes 15%-25%toward the near-surface PM_(2.5)concentrations during the severe PM pollution period under the four synoptic patterns. 展开更多
关键词 aerosol-radiation interactions wintertime particulate pollution synoptic patterns Guanzhong Basin
下载PDF
Subseasonal and Synoptic Variabilities of Precipitation over the Yangtze River Basin in the Summer of 2020 被引量:5
17
作者 Liudan DING Tim LI Ying SUN 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2021年第12期2108-2124,共17页
Summer precipitation over the Yangtze River basin(YRB)in 2020 experienced a strong subseasonal and synoptic fluctuation in addition to contributing to an exceptionally large seasonal mean precipitation.The cause of th... Summer precipitation over the Yangtze River basin(YRB)in 2020 experienced a strong subseasonal and synoptic fluctuation in addition to contributing to an exceptionally large seasonal mean precipitation.The cause of this higher-frequency fluctuation is examined based on observational analyses.Apart from the continuous northward movement of the climatological mei-yu rainband,the mei-yu rainbelt in the summer of 2020 experienced multiple northward and southward swings.The cause of the swings was attributed to the subseasonal variability of southerly winds to the south and northeasterly winds to the north of the YRB.In addition,synoptic-scale variability,characterized by the eastward propagation of low-level cyclonic vorticity and precipitation anomalies,was also commonplace in the summer of 2020.While the strengthening of both the subseasonal and synoptic variabilities in the summer of 2020 was attributed to the increase of the background mean moisture,the synoptic variability was greatly affected by the subseasonal rainfall variability.As a result,both the synoptic-scale and subseasonal variabilities contributed to the north-south swings of the rainbelt.The large-scale modulations by both the seasonal mean and subseasonal anomalies provide insight regarding the optimization of issuing accurate,extended-range forecasts of extreme weather events. 展开更多
关键词 Yangtze River precipitation synoptic and subseasonal variabilities meridional swings of a rainbelt large-scale modulation of high-frequency variability
下载PDF
Synoptic-Thermodynamic Analysis of Pervasive Hailstorm Case Study: Tehran, March 30, 2015 被引量:1
18
作者 Mahmoud Ahmadi Farzaneh Jafari +1 位作者 Tayebeh Akbari Azirani Abbasali Dadashiroudbari 《Journal of Geoscience and Environment Protection》 2017年第9期155-175,共21页
The objective here is to assess the atmospheric evaluations with respect to the perilous hailstorm phenomenon in Tehran. To accomplish this study, the available data regarding 9 (WW) present weather codes that reveal ... The objective here is to assess the atmospheric evaluations with respect to the perilous hailstorm phenomenon in Tehran. To accomplish this study, the available data regarding 9 (WW) present weather codes that reveal the hailstorm phenomenon with different intensities in 3 hrs observations for 6 meteorological stations of Tehran and vicinity for the period between 1985-2015 are applied. It is revealed that hail occurrence in Tehran is at its maximum in transition seasons of spring and fall between the hrs. 6 - 18 (UTC). It is found that the instability indexes intensify in the afternoon with a higher atmospheric flotation indicative of the possibility in occurrence of thunder hailstorm. Synoptic assessments point to the fact that the synoptic pattern created this thunder storm due to expansion of two: low-pressure cores over Arabia and North-Europe and the cold high-pressure over South Russia with a NS orientation have developed an intense pressure gradient over Tehran province. The study area being located at the left exit of sub-tropical jet stream has made a Baroclinic atmosphere condition on Tehran province. Access to great humidity resources of Mediterranean and Black seas and a drastic decrease of temperature at the upper level of the cloud verifies the hail occurrence on March 30th of 2015 in Tehran. 展开更多
关键词 HAIL Thermodynamic Indexes synoptic Blocking Systems TEHRAN Province
下载PDF
Barotropic Interaction between Planetary-and Synoptic-Scale Waves during the Life Cycles of Blockings 被引量:9
19
作者 罗德海 李建平 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2000年第4期649-670,共22页
In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstre... In this paper, in an equivalent barotropic framework a new forced nonlinear Schroedinger equation is proposed to examine the interaction between the planetary-scale waves and the localized synoptic-scale eddies upstream. With the help of the perturbed inverse scattering transform method, nonlinear parameter equations can be derived to describe the evolution of the dipole soliton amplitude, frequency, group velocity and phase under the forcing of localized synoptic-scale eddies. The numerical solutions of these equations predict that in the interaction between the weak dipole soliton (weak incipient dipole anomaly) and the synoptic-scale eddies, only when the high-frequency eddies themselves have a moderate parameter match they can near resonantly enhance a quasi-stationary large-amplitude split flow. The instantaneous total streamfunction field (the sum of background westerly wind, envelope Rossby soliton and synoptic-scale waves) is found to be very similar to the observed Berggren-type blocking on the weather map(Berggren et al. 1949). The role of synoptic-scale eddies is to increase the amplitude of large-scale dipole anomaly flow, and to decrease its group velocity, phase velocity and zonal wavenumber so that the dipole anomaly system can be amplified and transferred from dispersive system to very weak dispersive one. This may explain why and how the synoptic-scale eddies can reinforce and maintain vortex pair block. Furthermore, it is clearly found that during the prevalence of the vortex pair block the synoptic-scale eddies are split into two branches around the vortex pair block due to the feedback of amplified dipole block. Key words Envelope Rossby solilon - Blocking - Synoptic-to-planetary scale interaction This research was supported jointly by the Foundation for University Key Teacher by the Ministry of Education and by the National Natural Science Foundation of China (49775266, 49905007)), the Knowledge Innovation Key Project of Chinese Academy of Sciences in the Resource Environment Field (Grant No. KZCX 2-203) and the National Key Foundation Research Project (G1998040900, Part I). 展开更多
关键词 Envelope Rossby solilon Blocking synoptic-to-planetary scale interaction
下载PDF
Electronic Synoptic Reporting of Thyroid Nodules: Potential for Reduction in Number of Patients Undergoing Thyroid Nodule Biopsies 被引量:2
20
作者 Jimmy Tanche Wang Paul Babyn +1 位作者 Gary Groot Rob Otani 《Open Journal of Radiology》 2016年第3期233-242,共11页
Purpose: The objective of the study was to design and implement an electronic synoptic report for thyroid sonography that incorporates the thyroid imaging reporting and data system (TIRADS) and assess potential for re... Purpose: The objective of the study was to design and implement an electronic synoptic report for thyroid sonography that incorporates the thyroid imaging reporting and data system (TIRADS) and assess potential for reducing unnecessary fine needle aspiration biopsies (FNAB) of thyroid nodules. Methods: The electronic synoptic report was developed using a relational database based on elements from TIRADS and a multidisciplinary consensus statement for thyroid reporting. A retrospective analysis of 138 patients with previously reported thyroid sonographic exams was evaluated for the presence of these elements. The electronic synoptic report calculates the TIRADS score and generates a formal report. Using the TIRADS score the potential decrease in unnecessary FNAB was estimated. Results: Key TIRADS elements were variously reported ranging from 43% for the thyroid nodule’s architecture as solid or cystic. Thyroid nodule echogenicity and calcification was commented in 27% and 23%, respectively. Other features of the TIRADS score were commented in 0% to 8% of the official reports. Estimated reduction for potentially reduced need for FNAB was 34.5%. Conclusions: This study is the first implementation of synoptic reporting using a relational database for sonography of thyroid nodules. Implementation of an electronic standardized synoptic reporting system may facilitate more accurate, and more comprehensive reporting for thyroid ultrasound scanning of thyroid nodules. The use of TIRADS was estimated to be able to potentially reduce the need for FNAB which was significant. 展开更多
关键词 synoptic Reporting Thyroid Nodules Thyroid Cancer Fine Needle Aspiration Biopsy Thyroid Imaging Reporting and Data System
下载PDF
上一页 1 2 71 下一页 到第
使用帮助 返回顶部