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Intraseasonal Variability of Summertime Surface Air Temperature over Mid-High-Latitude Eurasia and Its Prediction Skill in S2S Models

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Journal of Meteorological Research 2021年第5期35卷 815-830页

作者： Jing CUI Shuangyan YANG tim LI Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environmental Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science&TechnologyNanjing 210044China International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and TechnologyUniversity of HawaiiHonoluluHI 96822USA

Features of the dominant modes of surface air temperature(SAT)on the intraseasonal timescale over the mid-highlatitude Eurasia(MHE)during boreal summer(June-September)are investigated based on the ERA5 reanalysis data from 1979 to *** intraseasonal variability(ISV)of SAT over MHE is primarily characterized by an eastward propagation along 60°N,which is found to impact the regional weather in China,including summertime extreme hot and cool *** forecast skill and potential predictability of the ISV of SAT over MHE are assessed for 5 dynamical models that have participated in the subseasonal-to-seasonal(S2 S)prediction project,by analyzing12 years’(1999-2010)model reforecast/hindcast *** using the principal component(PC)index of the leading intraseasonal SAT modes as a predictand,we found that the forecast skill for ISV of SAT can reach out to 11-17 days,and the ECMWF model exhibits the best *** the S2 S models tend to show 1)a relatively higher skill for strong intraseasonal oscillation(ISO)cases,2)a systematic underestimate of the amplitude of the SAT ISV signal,and 3)different skills during different phases of ISO *** of potential predictability based on the perfectmodel assumption reveals a 4-6-day skill gap for most models,and the skill gap also varies among different phases of ISO *** results imply the need for continued development of operational forecasting systems to improve the actual prediction skills for the ISV of SAT over MHE.

关键词： surface air temperature(SAT) intraseasonal variability(ISV) mid-high-latitude Eurasia(MHE) subseasonal-to-seasonal(S2S)prediction prediction skill predictability

Subseasonal and Synoptic Variabilities of Precipitation over the Yangtze River Basin in the Summer of 2020

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Advances in Atmospheric Sciences 2021年第12期38卷 2108-2124页

作者： Liudan DING tim LI Ying SUN Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA National Climate Center Beijing 100081China

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 *** cause of this higher-frequency fluctuation is examined based on observational *** 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 *** cause of the swings was attributed to the subseasonal variability of southerly winds to the south and northeasterly winds to the north of the *** addition,synoptic-scale variability,characterized by the eastward propagation of low-level cyclonic vorticity and precipitation anomalies,was also commonplace in the summer of *** 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 *** a result,both the synoptic-scale and subseasonal variabilities contributed to the north-south swings of 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.

关键词： Yangtze River precipitation synoptic and subseasonal variabilities meridional swings of a rainbelt large-scale modulation of high-frequency variability

LiDAR mapping of ground damage in a heading re-orientation case study

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International Journal of Mining Science and Technology 2021年第1期31卷 67-74页

作者： Nicole Evanek Brent Slaker Anthony Iannacchione tim Miller National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA University of Pittsburgh PittsburghPA 15260USA East Fairfield Coal Company North LimaOH 44452USA

The Subtropolis Mine is a room-and-pillar mine extracting the Vanport limestone near Petersburg,Ohio,*** February of 2018,mine management began implementing a heading re-orientation to better control the negative effects of excessive levels of horizontal *** conditions in the headings improved,but as expected,stress-related damage concentrated within *** mine operator has worked to lessen the impact of the instabilities in the outby crosscuts by implementing several engineering *** the implementation of each control,conditions were monitored and analyzed using observational and measurement techniques including 3D LiDAR *** the heading re-orientation,several 3D LiDAR surveys have been conducted and analyzed by researchers from the National Institute for Occupational Safety and Health(NIOSH).This study examines(1)the characteristics of each 3D LiDAR survey,(2)the change in the detailed strata conditions in response to stress concentrations,and(3)the change detection techniques between 3D LiDAR surveys to assess entry ***,the 3D LiDAR surveys proved to be a useful tool for characterizing ground instability and assessing the effectiveness of the engineering controls used in the heading re-orientation at the Subtropolis Mine.

关键词： Ground control Limestone Horizontal stress Stress control layout Crosscut Windows

Prime number theorems for Rankin-Selberg L-functions over number fields

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Science China Mathematics 2011年第1期54卷 35-46页

作者： GILLESPIE tim JI GuangHua Department of Mathematics The University of Iowa Iowa City Iowa 52242 USA School of Mathematics Shandong University Jinan 250100 China

In this paper we define a Rankin-Selberg L-function attached to automorphic cuspidal represen-tations of GLm(AE) × GLm (AF ) over cyclic algebraic number fields E and F which are invariant under the Galois action,by ... 详细信息

关键词：函数连接素数定理代数数域塞尔伽罗瓦长征证明

Day length constrains the time budget of aphid predators

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Insect Science 2019年第1期26卷 164-170页

作者： Jens Joschinski tim Kiess Jochen Krauss Department of Animal Ecology and Tropical Biology BiocentreUniversity of WEirzburgWEtrzburgGermany

Phenology shifts and range expansions cause organisms to experience novel day length-temperature *** on the temporal niche,organisms may benefit or suffer from changes in day length,thus potentially affecting phenological adaptation. We assessed the impact of day length changes on larvae of Chrysoperla carnea (Stephens) and Episyrphus balteatus (De Geer),both of which prey on *** *** are night-active,whereas those of *** appear to be *** subjected both species in climate chambers to day lengths of 16 :8 L :D and,to circumvent diapause responses,20 :4 L :*** recorded development times and predation rates of both species. *** grew 13%faster in the 16 :8 L :D treatment and preyed on significantly more *** contrast,*** grew 13% faster in the 20 :4 L :D treatment and higher predation rates in 20 :4 L :D were marginally *** results show that day length affects development and predation,but that the direction depends on species. Such differences in the use of day length may alter the efficiency ofbiocontrol agents in a changing climate.

关键词： Chiysoperla carnea climate change Episyrphus balteatus insect timing phenology photoperiod

Impact of 10-60-Day Low-Frequency Steering Flows on Straight Northward-Moving Typhoon Tracks over the Western North Pacific

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Journal of Meteorological Research 2018年第3期32卷 394-409页

作者： Qiao LIU tim LI Weican ZHOU Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environmental ChangeCollaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology International Pacific Research Center and Department of Atmospheric Sciences School of Ocean and Earth Science and Technology University of Hawaii

This study investigates the impact of low-frequency(intraseasonal and interannual) steering flows on straight northward-moving(defined as a meridional displacement two times greater than the zonal displacement) typhoons over the western North Pacific using observational data. The year-to-year change in the northward-moving tracks is affected by the interannual change in the location and intensity of the subtropical high. A strengthened northward steering flow east of 120°E and a weakened easterly steering flow south of the subtropical high favor more frequent straight northward tracks. Examining each of the individual northward-moving typhoons shows that they interact with three types of intraseasonal(10-60-day) background flows during their northward journey. The first type is the monsoon gyre pattern, in which the northward-moving typhoon is embedded in a closed cyclonic monsoon gyre circulation. The second type is the wave train pattern, where a cyclonic(anticyclonic) vorticity circulation is located to the west(east) of the northward-moving typhoon center. The third type is the mid-latitude trough pattern, in which the northward-moving typhoon center is located in the maximum vorticity region of the trough.

关键词： intraseasonal steering flow interannual steering flow straight northward-moving typhoon

Three-type MJO Initiation processes over the Western Equatorial Indian Ocean

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Advances in Atmospheric Sciences 2015年第9期32卷 1208-1216页

作者： MEI Shuangli tim LI CHEN Wen Center for Monsoon System Research Institute of Atmospheric PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences International Laboratory on Climate and Environment Change and Key Laboratory of Meteorological Disaster of Ministry of Education Nanjing University of Information Science and Technology International Pacific Research Center Department of MeteorologySchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at Manoa

Thirty strong Madden–Julian Oscillation（MJO） events in boreal winter 1982–2001 are selected to investigate the triggering processes of MJO convection over the western equatorial Indian Ocean（IO）.These MJO events are classified into three types,according to their dynamic and thermodynamic precursor signals in *** Type I,a remarkable increase in low-level moisture occurs,on average,7 days prior to the convection *** low-level moistening is mainly due to the advection of the background mean moisture by easterly wind anomalies over the equatorial *** Type II,lower-tropospheric ascending motion anomalies develop,on average,4 days prior to the *** cause of this ascending motion anomaly is attributed to the anomalous warm advection,set up by a suppressed MJO phase in the equatorial *** Type III,there are no clear dynamic and thermodynamic precursor signals in *** convection might be triggered by energy accumulation in the upper layer associated with Rossby wave activity fluxes originated from the midlatitudes.

关键词： MJO Indian Ocean dynamic precursor signal thermodynamic precursor signal

Strengthening of the Walker Circulation under Global Warming in an Aqua-Planet General Circulation Model Simulation

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Advances in Atmospheric Sciences 2015年第11期32卷 1473-1480页

作者： tim LI ZHANG Lei Hiroyuki MURAKAMI AORC/IPRC and Department of Atmospheric Sciences University of Hawaii International Laboratory on Climate and Environment Change and Key Laboratory of Meteorological Disaster Nanjing University of Information Science and Technology Climate Research Department Meteorological Research Institute

Most climate models project a weakening of the Walker circulation under global warming scenarios. It is argued, based on a global averaged moisture budget, that this weakening can be attributed to a slower rate of rainfall increase compared to that of moisture increase, which leads to a decrease in ascending motion. Through an idealized aqua-planet simulation in which a zonal wavenumber-1 SST distribution is prescribed along the equator, we find that the Walker circulation is strengthened under a uniform 2-K SST warming, even though the global mean rainfall-moisture relationship remains the same. Further diagnosis shows that the ascending branch of the Walker cell is enhanced in the upper troposphere but weakened in the lower troposphere. As a result, a ＂double-cell＂ circulation change pattern with a clockwise （anti-clockwise） circulation anomaly in the upper （lower） troposphere forms, and the upper tropospheric circulation change dominates. The mechanism for the formation of the ＂double cell＂ circulation pattern is attributed to a larger （smaller） rate of increase of diabatic heating than static stability in the upper （lower） troposphere. The result indicates that the future change of the Walker circulation cannot simply be interpreted based on a global mean moisture budget argument.

关键词： Walker circulation global warming aqua-planet simulation

Microscale study of frictional properties of graphene in ultra high vacuum

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Friction 2015年第2期3卷 161-169页

作者： Diego MARCHETTO tim FESER Martin DIENWIEBEL Fraunhofer-Institute for Mechanics of Materials Microtribology CenterμTCWöhlerstr.1179108 FreiburgGermany Karlsruhe Institute of Technology Institute for Applied Materials-Computational Materials Science IAM-CMSKaiserstr.1276131 KarlsruheGermany

We report on the frictional properties of epitaxial graphene on SiC in ultra high *** have been performed using a microtribometer in the load regime of 0.5 to 1 *** observed that a ruby sphere sliding against graphene results in very low friction coefficients ranging from 0.02 to *** friction and also the stability of the graphene layer is higher than that under similar conditions in ambient *** friction shows a load *** it was found that graphene masks the frictional anisotropy which was observed on the SiC surface.

关键词： graphene SiC friction vacuum microtribology anisotropy