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Some Characteristics of the Surface Boundary Layer of a Strong Cold Air Process over Southern China

Advances in atmospheric Sciences 2013年第1期30卷 210-218页

作者：刘熙明程雪玲吴琼傅敏宁曾庆存 Meteorological Sciences institute of Jiangxi Province state key laboratory of atmospheric Boundary Layer Physics and atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of Sciences state key laboratory of severe weather Chinese Academy of Meteorological Sciences Meteorological Sciences institute of Jiangxi Province Nanchang 330046 Nanjing University of Information Science & Technology

In southern China, cold air is a common weather process during the winter season; it can cause strong wind, sharp temperature decreases, and even the snow or freezing rain events. However, the features of the atmospheric boundary layer during cold air passage are not clearly understood due to the lack of comprehensive observation data, especially regarding turbulence. In this study, four-layer gradient meteorological observation data and one-layer, 10-Hz ultrasonic anemometer-thermometer monitoring data from the northern side of Poyang Lake were employed to study the main features of the surface boundary layer during a strong cold-air passage over southern China. The results show that, with the passage of a cold air front, the wind speed exhibits low-frequency variations and that the wind systematically descends. During the strong wind period, the wind speed increases with height in the surface layer. Regular gust packets are superimposed on the basic strong wind flow. Before the passage of cold air, the wind gusts exhibit a coherent structure. The wind and turbulent momentum fluxes are small, although the gusty wind momentum flux is slightly larger than the turbulent momentum flux. However, during the invasion of cold air, both the gusty wind and turbulent momentum fluxes increase rapidly with wind speed, and the turbulent momentum flux is larger than the gusty wind momentum flux during the strong wind period. After the cold air invasion, this structure almost disappears.

关键词： cold air surface boundary layer gusty wind descending motion

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On the Two Successive Supercold Waves Straddling the End of 2020 and the Beginning of 2021

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Advances in atmospheric Sciences 2022年第4期39卷 591-608页

作者： Cholaw BUEH Jingbei PENG Dawei LIN Bomin CHEN International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China state key laboratory of severe weather(lasw)&key laboratory for Cloud Physics of China Meteorological Administration Chinese Academy of Meteorological SciencesBeijing 100081China Shanghai Climate Center Shanghai 200030China

Two supercold waves straddling 2020 and 2021 successively hit China and caused record-breaking extremely low *** this study,the distinct features of these two supercold waves are analyzed on the medium-range time *** blocking pattern from the Kara Sea to Lake Baikal characterized the first cold wave,while the large-scale tilted ridge and trough over the Asian continent featured the second cold *** to the cold waves,both the northwest and hyperpolar paths of cold air contributed to a zonally extensive cold air accumulation in the key region of *** might be the primary reason why strong and extensive supercold waves occur even under the Arctic amplification *** two cold waves straddling 2020 and 2021 exhibited distinct features:(1)the blocking circulation occurred to the north or the east of the Ural Mountains and was not confined only to the Ural Mountains as it was for the earlier cold waves;(2)the collocation of the Asian blocking pattern and the polar vortex deflection towards East Asia preferred the hyperpolar path of cold air accumulation and the subsequent southward outburst;and(3)both high-and low-frequency processes worked in concert,leading to the very intense cold *** cold air advance along the northwest path,which coincides with the southeastward intrusion of the Siberian High(SH)front edge,is associated with the high-frequency process,while the cold air movement along the hyperpolar path,which is close to the eastern edge of the SH,is controlled by the low-frequency process.

关键词： cold wave Siberian high hyperpolar path blocking large-scale tilted ridge and trough

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Targeted Observations for Improving Prediction of the NAO Onset

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Journal of Meteorological Research 2019年第6期33卷 1044-1059页

作者： Guokun DAI Mu MU Zhina JIANG Department of atmospheric and Oceanic Sciences&institute of atmospheric Sciences Fudan UniversityShanghai 200438 state key laboratory of severe weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Based on the viewpoint that the North Atlantic Oscillation(NAO)has an intrinsic timescale of approximate two weeks and can be treated as an initial value problem,targeted observations for improving the prediction of the onset of NAO events are investigated by using the conditional nonlinear optimal perturbation(CNOP)method with a quasigeostrophic *** results show that flow-dependent sensitive areas for the prediction of NAO onset are mainly located over North Atlantic and its upstream *** observations over the main sensitive areas could improve NAO onset prediction in most cases(approximately 75%)due to reduced errors in anomalous eddy vorticity forcing(EVF)projection in the typical NAO ***,a flow-independent sensitive area is determined based on the winter climatological flow,which is located over North America and its adjacent *** NAO onset prediction can also be improved by targeted observations over the flow-independent sensitive area,but the skill improvement is somewhat lower than that derived from observations over the flow-dependent sensitive *** above results indicate that targeted observations over sensitive areas identified by the CNOP method can help to improve the onset prediction of NAO events.

关键词： North Atlantic Oscillation(NAO) targeted observations eddy vorticity forcing(EVF) conditional nonlinear optimal perturbation(CNOP)

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Water Vapor Transport around the Tibetan Plateau and Its Effect on Summer Rainfall over the Yangtze River Valley

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Journal of Meteorological Research 2016年第4期30卷 472-482页

作者：李驰钦左群杰徐祥德高守亭 key laboratory of Cloud-Precipitation Physics and severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029 University of Chinese Academy of Sciences Beijing 100049 state key laboratory of severe weather Chinese Academy of Meteorological SciencesBeijing 100081

The water vapor transport around the Tibetan Plateau（TP） and its effect on the rainfall in the Yangtze River valley（YRV） in summer are investigated by decomposing the moisture transport into rotational and divergent *** on the ERA-Interim and PREC/L（Precipitation Reconstruction over Land） data from 1985 to 2014,the vertically integrated features of the two components are *** results show that the divergent part dominates the western TP while the rotational part dominates the rest of the TP,implying that moisture may be mostly locally gathered in the western TP but could be advected to/from elsewhere over the rest of the *** divergent and rotational moisture fluxes exhibit great temporal variability along the southern periphery of the TP,showing sensitivity of water vapor to the steep topography *** analysis reveals that it is over the southeastern corner of the TP and to its south that a significant correlation between rotational zonal moisture transport and summer rainfall in the YRV appears,suggesting that the southeastern corner of the TP may serve as a moisture transport bridge between the South Asian（Indian） monsoon and the East Asian *** composite analysis indicates that anomalous eastward（westward） zonal water vapor transport from the South Asian monsoon via the southeastern corner of the TP favors more（less） precipitation in the YRV in summer.

关键词： moisture transport Tibetan Plateau rotational component divergent component Yangtze River valley rainfall

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Robust prediction of hourly PM2.5 from meteorological data using LightGBM

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National Science Review 2021年第10期8卷 115-126页

作者： Junting Zhong Xiaoye Zhang Ke Gui Yaqiang Wang Huizheng Che Xiaojing Shen Lei Zhang Yangmei Zhang Junying Sun Wenjie Zhang state key laboratory of severe weather and key laboratory of atmospheric Chemistry of China Meteorological Administration Chinese Academy of Meteorological Sciences School of Earth and Planetary Sciences University of Chinese Academy of Sciences Center for Excellence in Regional atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences

Retrieving historical fine particulate matter(PM2.5) data is key for evaluating the long-term impacts of PM2.5on the environment, human health and climate change. Satellite-based aerosol optical depth has been used to estimate PM2.5, but estimations have largely been undermined by massive missing values, low sampling frequency and weak predictive capability. Here, using a novel feature engineering approach to incorporate spatial effects from meteorological data, we developed a robust Light GBM model that predicts PM2.5at an unprecedented predictive capacity on hourly（R2= 0.75）, daily（R2= 0.84）, monthly（R2= 0.88） and annual（R2= 0.87） timescales. By taking advantage of spatial features, our model can also construct hourly gridded networks of PM2.5. This capability would be further enhanced if meteorological observations from regional stations were incorporated. Our results show that this model has great potential in reconstructing historical PM2.5datasets and real-time gridded networks at high spatial-temporal resolutions. The resulting datasets can be assimilated into models to produce long-term re-analysis that incorporates interactions between aerosols and physical processes.

关键词： PM_(2.5) spatial features hourly prediction high accuracy gridded networks

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Simulation and Improvements of Oceanic Circulation and Sea Ice by the Coupled Climate System Model FGOALS-f3-L

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Advances in atmospheric Sciences 2020年第10期37卷 1133-1148页

作者： Yuyang GUO Yongqiang YU Pengfei LIN Hailong LIU Bian HE Qing BAO Bo AN Shuwen ZHAO and Lijuan HUA state key laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China state key laboratory of severe weather(lasw) Chinese Academy of Meteorological SciencesBeijing 100081China

This study documents simulated oceanic circulations and sea ice by the coupled climate system model FGOALS-f3-L developed at the state key laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics,institute of atmospheric Physics,Chinese Academy of Sciences,under historical forcing from phase 6 of the Coupled Model Intercomparison Project(CMIP6).FGOALS-f3-L reproduces the fundamental features of global oceanic circulations,such as sea surface temperature(SST),sea surface salinity(SSS),mixed layer depth(MLD),vertical temperature and salinity,and meridional overturning *** are notable improvements compared with the previous version,FGOALS-s2,such as a reduction in warm SST biases near the western and eastern boundaries of oceans and salty SSS biases in the tropical western Atlantic and eastern boundaries,and a mitigation of deep MLD biases at high ***,several obvious biases *** most significant biases include cold SST biases in the northwestern Pacific(over 4°C),freshwater SSS biases and deep MLD biases in the subtropics,and temperature and salinity biases in deep ocean at high *** simulated sea ice shows a reasonable distribution but stronger seasonal cycle than *** spatial patterns of sea ice are more realistic in FGOALS-f3-L than its previous version because the latitude–longitude grid is replaced with a tripolar grid in the ocean and sea ice *** most significant biases are the overestimated sea ice and underestimated SSS in the Labrador Sea and Barents Sea,which are related to the shallower MLD and weaker vertical mixing.

关键词： CMIP6 FGOALS-f3-L historical evaluation ocean sea ice

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Opposing Trends of Winter Cold Extremes over Eastern Eurasia and North America under Recent Arctic Warming

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Advances in atmospheric Sciences 2020年第12期37卷 1417-1434页

作者： Shuangmei MA Congwen ZHU state key laboratory of severe weather and institute of Climate System Chinese Academy of Meteorological SciencesBeijing 100081China

Under recent Arctic warming,boreal winters have witnessed severe cold surges over both Eurasia and North America,bringing about serious social and economic ***,we investigated the changes in daily surface air temperature(SAT)variability during the rapid Arctic warming period of 1988/89–2015/16,and found the daily SAT variance,mainly contributed by the sub-seasonal component,shows an increasing and decreasing trend over eastern Eurasia and North America,*** cold extremes(defined as days with daily SAT anomalies below 1.5 standard deviations)dominated the increase of the daily SAT variability over eastern Eurasia,while decreasing cold extremes dominated the decrease of the daily SAT variability over North *** circulation regime of cold extremes over eastern Eurasia(North America)is characterized by an enhanced high-pressure ridge over the Urals(Alaska)and surface Siberian(Canadian)*** data analyses and model simulations show the recent strengthening of the high-pressure ridge over the Urals was associated with warming of the Barents–Kara seas in the Arctic region,while the high-pressure ridge over Alaska was influenced by the offset effect of Arctic warming over the East Siberian–Chukchi seas and the Pacific decadal oscillation(PDO)–like sea surface temperature(SST)anomalies over the North *** transition of the PDO-like SST anomalies from a positive to negative phase cancelled the impact of Arctic warming,reduced the occurrence of extreme cold days,and possibly resulted in the decreasing trend of daily SAT variability in North *** multi-ensemble simulations of climate models confirmed the regional Arctic warming as the driver of the increasing SAT variance over eastern Eurasia and North America and the overwhelming effect of SST forcing on the decreasing SAT variance over North ***,the regional response of winter cold extremes at midlatitudes to the Arctic warming could be different due to the dis

关键词： daily surface air temperature variability extreme cold days Arctic warming eastern Eurasia North America

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Comparison of Two Air Pollution Episodes over Northeast China in Winter 2016/17 Using Ground-Based Lidar

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Journal of Meteorological Research 2018年第2期32卷 313-323页

作者： Yanjun MA Hujia ZHAO Yunsheng DONG Huizheng CHE Xiaoxiao LI Ye HONG Xiaolan LI Hongbin YANG Yuche LIU Yangfeng WANG Ningwei LIU Cuiyan SUN institute of atmospheric Environment China Meteorological Administration Shenyang 110016 key laboratory of Environmental Optics and Technology Anhui Institute of Optics and Fine Mechanics Chinese Academy of Sciences Hefei 230031 state key laboratory of severe weather/institute of atmospheric composition Chinese Academy of Meteorological Sciences Beijing 100081 Dalian Municipal Meteorological Observatory Dalian 116001 Jinan Center of Aviation Control Jinan 250107

This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22（E1） and 25–26（E2） December 2016 in Northeast China. The visibility, particulate matter（PM） mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer（PBL） properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January *** suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1,whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.

关键词： aerosol pollution ground-based lidar Northeast China

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A Study on the Dynamic Mechanism of the Formation of Mesoscale Vortex in Col Field

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Advances in atmospheric Sciences 2012年第6期29卷 1215-1226页

作者：姜勇强王元黄泓 key laboratory of Mesoscale severe weather/Ministry of Education of China and School of Atmospheric SciencesNanjing University institute of Meteorology PLA University of Science and Technology

The mesoscale vortex associated with a mesoscale low-level jet （mLLJ） usually causes heavy rainfall in the col field. The col field is defined as a region between two highs and two lows, with the isobaric surface similar to a col. Using a two-dimensional shallow water model, the meso-β scale vortex couplets （MβVCs） induced by eight types of mesoscale wind perturbations in an ideal col field were numerically simulated. With the sizes of -100 km, the MβVCs induced by northerly perturbation （NP） and southerly perturbation （SP） moved toward the col point. The sizes of MβVCs induced by southwesterly perturbation （SWP）, southeasterly perturbation （SEP）, northwesterly perturbation （NWP）, and northeasterly perturbation （NEP） were relatively small for the perturbations moving toward dilatation axis. The MβVC induced by easterly perturbation （EP） and westerly perturbation （WP） could not develop because they quickly moved away from the col point, before the circulation could form. The size of the circulation was determined by the distance between the vortex and the col point. The closer to the col point the vortex was, the larger the size of vortex. The comparisons of maximum vorticity and vorticity root mean square error （RMSE） of the NP, the SWP, and the WP show that the maximum vorticity and the vorticity RMSE of the NP decreased slower than other perturbations. Therefore, the weak environment of the col field favors the maintenance of vorticity and the formation of vortex. When a mesoscale vortex forms near the col point or moves toward the col point, it may maintain a quasitationary state in the stable col field.

关键词： col field mesoscale vortex mesoscale low-level jet point vorticity numerical simulation

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Application of Conditional Nonlinear Optimal Perturbation to Targeted Observation Studies of the Atmosphere and Ocean

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Journal of Meteorological Research 2014年第5期28卷 923-933页

作者：穆穆王强段晚锁姜智娜 key laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences state key laboratory of Numerical Modeling for atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Sciences state key laboratory of severe weather Chinese Academy of Meteorological Sciences

This paper reviews progress in the application of conditional nonlinear optimal perturbation to targeted observation studies of the atmosphere and ocean in recent years, with a focus on the E1 Nifio-Southern Oscillation （ENSO）, Kuroshio path variations, and blocking events. Through studying the optimal precursor （OPR） and optimally growing initial error （OGE） of the occurrence of the above events, the similarity and localization features of OPR and OGE spatial structures have been found for each event. Ideal hindcasting experiments have shown that, if initial errors are reduced in the areas with the largest amplitude for the OPR and OGE for ENSO and Kuroshio path variations, the forecast skill of the model for these events is significantly improved. Due to the similarity between patterns of the OPR and OGE, additional observations implemented in the same sensitive region would help to not only capture the precursors, but also reduce the initial errors in the predictions, greatly increasing the forecast abilities. The similarity and localization of the spatial structures of the OPR and OGE during the onset of blocking events have also been investigated, but their application to targeted observation requires further study.

关键词： conditional nonlinear optimal perturbation targeted observation ENSO Kuroshio path vari-ations blocking

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