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Regional and Global Land Data Assimilation Systems: Innovations,Challenges, and Prospects
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作者 Youlong XIA Zengchao HAO +5 位作者 Chunxiang SHI Yaohui LI Jesse MENG Tongren XU Xinying WU Baoqing ZHANG 《气象学报:英文版》 SCIE CSCD 2019年第2期159-189,共31页
Since the North American and Global Land Data Assimilation Systems(NLDAS and GLDAS) were established in2004, significant progress has been made in development of regional and global LDASs. National, regional, projectb... Since the North American and Global Land Data Assimilation Systems(NLDAS and GLDAS) were established in2004, significant progress has been made in development of regional and global LDASs. National, regional, projectbased, and global LDASs are widely developed across the world. This paper summarizes and overviews the development, current status, applications, challenges, and future prospects of these LDASs. We first introduce various regional and global LDASs including their development history and innovations, and then discuss the evaluation, validation, and applications(from numerical model prediction to water resources management) of these LDASs. More importantly, we document in detail some specific challenges that the LDASs are facing: quality of the in-situ observations, satellite retrievals, reanalysis data, surface meteorological forcing data, and soil and vegetation databases;land surface model physical process treatment and parameter calibration;land data assimilation difficulties;and spatial scale incompatibility problems. Finally, some prospects such as the use of land information system software, the unified global LDAS system with nesting concept and hyper-resolution, and uncertainty estimates for model structure,parameters, and forcing are discussed. 展开更多
关键词 LAND data ASSIMILATION system (LDAS) REGIONAL and GLOBAL LDASs in-situ observation satellite RETRIEVAL LAND surface model (LSM)
The alternative of CubeSat-based advanced infrared and microwave sounders for high impact weather forecasting 预览
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作者 LI Zhenglong LI Jun +12 位作者 SCHMIT Timothy J. WANG Pei LIM Agnes LI Jinlong NAGLE Fredrick W. BAI Wenguang OTKIN Jason A. ATLAS Robert HOFFMAN Ross N. BOUKABARA Sid-Ahmed ZHU Tong BLACKWELL William J. PAGANO Thomas S. 《大气和海洋科学快报:英文版》 CSCD 2019年第2期80-90,共11页
近年来,小卫星技术的发展给传统气象卫星提供了经济有效的替补方案。本文针对可能出现的传统气象卫星的缺失情形,借助快速的区域观测系统模拟试验,探索了利用小卫星填补空缺的可能性。研究表明,单个小卫星,无论是近红外高光谱还是微波... 近年来,小卫星技术的发展给传统气象卫星提供了经济有效的替补方案。本文针对可能出现的传统气象卫星的缺失情形,借助快速的区域观测系统模拟试验,探索了利用小卫星填补空缺的可能性。研究表明,单个小卫星,无论是近红外高光谱还是微波探测仪,都能够对局地强风暴天气的预报有所改进。然而,为了填补传统卫星缺失带来的影响,需要发射三颗甚至更多的小卫星来增加观测的覆盖面,以弥补小卫星精度略低、通道略少的缺陷。 展开更多
关键词 OSSE CUBESAT sounder high-impact WEATHER
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Simulation Study of Cloud Properties Affected by Heterogeneous Nucleation Using the GRAPES_SCM during the TWP-ICE Campaign
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作者 Zhe LI Qijun LIU +2 位作者 Zhanshan MA Jiong CHEN Qingu JIANG 《气象学报:英文版》 SCIE CSCD 2019年第4期734-746,共13页
This study used the Global/Regional Assimilation and PrEdiction System Single-Column Model(GRAPES_SCM)to simulate monsoon precipitation with deep convective cloud and associated cirrus during the Tropical Warm Pool In... This study used the Global/Regional Assimilation and PrEdiction System Single-Column Model(GRAPES_SCM)to simulate monsoon precipitation with deep convective cloud and associated cirrus during the Tropical Warm Pool International Cloud Experiment(TWP-ICE),especially during the active and suppressed monsoon periods.Four cases with different heterogeneous nucleation parameterizations were simulated by using the ensemble method.All simulations clearly separated the active and suppressed monsoon periods,and they reproduced the major characteristics of monsoonal cloud such as the total cloud hydrometeor mixing ratio distribution,and precipitation and radiation properties.The results showed that the number concentration production rate of different heterogeneous nucleation parameterizations varied substantially under the given temperature and water vapor mixing ratio.However,ice formation and precipitation during the monsoon period were affected only slightly by the different heterogeneous nucleation parameterizations.This study also captured clear competition between different ice formation processes. 展开更多
关键词 Liuma microphysics scheme monsoon precipitation cloud microphysics heterogeneous nucleation GRAPES_SCM
Double cores of the Ozone Low in the vertical direction over the Asian continent in satellite data sets 预览
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作者 Zhou Tang Dong Guo +8 位作者 YuCheng Su ChunHua Shi ChenXi Zhang Yu Liu XiangDong Zheng WenWen Xu JianJun Xu RenQiang Liu WeiLiang Li 《地球与行星物理:英文版》 CSCD 2019年第2期93-101,共9页
Using four satellite data sets(TOMS/SBUV,OMI,MLS,and HALOE),we analyze the seasonal variations of the total column ozone(TCO)and its zonal deviation(TCO*),and reveal the vertical structure of the Ozone Low(OV)over the... Using four satellite data sets(TOMS/SBUV,OMI,MLS,and HALOE),we analyze the seasonal variations of the total column ozone(TCO)and its zonal deviation(TCO*),and reveal the vertical structure of the Ozone Low(OV)over the Asian continent.Our principal findings are:(1)The TCO over the Asian continent reaches its maximum in the spring and its minimum in the autumn.The Ozone Low exists from May to September.(2)The Ozone Low has two negative cores,located in the lower and the upper stratosphere.The lower core is near 30 hPa in the winter and 70 hPa in the other seasons.The upper core varies from 10 hPa to 1 hPa among the four seasons.(3)The position of the Ozone Low in the lower and the upper stratosphere over the Asian continent shows seasonal variability. 展开更多
关键词 OZONE LOW DOUBLE core ASIAN CONTINENT SATELLITE data
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Propagation of positive,negative,and recoil leaders in upward lightning flashes 预览
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作者 XiuShu Qie ShanFeng Yuan +9 位作者 HongBo Zhang RuBin Jiang ZhiJun Wu MingYuan Liu ZhuLing Sun YunJiao Pu JinLiang Li Abhay Srivastava ZiLong Ma GaoPeng Lu 《地球与行星物理:英文版》 CSCD 2019年第2期102-110,共9页
Leader propagation is a fundamental issue in lightning physics.The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagne... Leader propagation is a fundamental issue in lightning physics.The propagation characteristics of positive leaders and negative leaders are summarized and compared based on data from high-speed camera and electromagnetic field in rocket-triggered lightning and tower-initiated lightning discharges;available channel base current data recorded in rocket-triggered lightning are also used.The negative leaders propagate in a stepped fashion accompanied by many branches.The stems ahead of the negative leader tip determine the manner and direction of the leader propagation,and even the branching and winding of the lightning channel.The impulsive current,electromagnetic field,and related optical images suggest that the positive leader may develop in a step-like fashion at its initial stage of triggered lightning.However,the stepping processes of the positive leader are obviously different from those of the negative leader.Tower-initiated lightning revealed that the most conspicuous characteristics of the stepwise positive leader involve the intermittent brush-like corona zone in front of the leader tip and the luminosity enhancement of the channel behind the tip.In rockettriggered lightning flashes,the charge transferred during an individual step for the negative leader was nearly an order greater than for the positive counterpart.The successive streamers ahead of the leader tip are essential for both negative and positive leader propagation,and the stems could be formed from one or more streamers in the previous negative streamer zone with the main leader channel dim.High-resolution observation of tower lightning also revealed a new type of bidirectional recoil leader,with polarity contrary to the traditional one,traversing in negative channels associated with tower-initiated and rocket-triggered lightning. 展开更多
关键词 LIGHTNING PROPAGATION NEGATIVE LEADER POSITIVE LEADER RECOIL LEADER
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Tilt of the ring current during the main phases of intense geomagnetic storms
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作者 LIU BaoJia ZHANG XiaoXin HE Fei 《中国科学:技术科学英文版》 SCIE EI CAS CSCD 2019年第5期820-828,共9页
Based on the data from the SuperMAG collaboration in 2000–2014, the magnetic latitude(MLAT) location of the ring current(RC) denoted by the MLAT of the maximum horizontal magnetic disturbance during the main phase of... Based on the data from the SuperMAG collaboration in 2000–2014, the magnetic latitude(MLAT) location of the ring current(RC) denoted by the MLAT of the maximum horizontal magnetic disturbance during the main phase of 67 intense geomagnetic storms(Dst ≤-100 nT) are derived. The results show that the maximum horizontal magnetic disturbance does not always occur in the magnetic equator, indicating that the RC might be tilted in the latitudinal direction during these storms. Specifically, the tilt of the RC near the day-night line is affected by the direction of solar wind. When the solar wind flows southward against the magnetic equatorial plane, the RC is more likely to show a dayside-lifted tilt. When the solar wind flows northward, the pattern is opposite. Tilts of the RC near the dawn-dusk line are also found in most of these storms. The location of the RC is mainly lifted in the dusk side and declined in the dawn side for positive IMF BY, while the tilt is reversed for negative IMF BY. A possible interpretation might be the IMF BY-related twisting of the geomagnetic field. Besides, the monthly averaged MLAT of the fitted RC also varies with seasons. It is shifted to the southern hemisphere in the northern summer and to the northern hemisphere in the northern winter, which might indicate that the RC is not centered on a single plane. Such a seasonal variation might be related to the angle between the solar wind and the magnetic equatorial plane. 展开更多
关键词 TILT of ring current GEOMAGNETIC STORM solar wind INTERPLANETARY magnetic field
Spatial and temporal evolution of landfast ice near Zhongshan Station,East Antarctica,over an annual cycle in 2011/2012 预览
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作者 Jiechen Zhao Qinghua Yang +8 位作者 Bin Cheng Matti Lepparanta Fengming Hui Surui Xie Meng Chen Yining Yu Zhongxiang Tian Ming Li Lin Zhang 《海洋学报:英文版》 SCIE CAS CSCD 2019年第5期51-61,共11页
Annual observations of first-year ice(FYI)and second-year ice(SYI)near Zhongshan Station,East Antarctica,were conducted for the first time from December 2011 to December 2012.Melt ponds appeared from early December 20... Annual observations of first-year ice(FYI)and second-year ice(SYI)near Zhongshan Station,East Antarctica,were conducted for the first time from December 2011 to December 2012.Melt ponds appeared from early December 2011.Landfast ice partly broke in late January,2012 after a strong cyclone.Open water was refrozen to form new ice cover in mid-February,and then FYI and SYI co-existed in March with a growth rate of 0.8 cm/d for FYI and a melting rate of 2.7 cm/d for SYI.This difference was due to the oceanic heat flux and the thickness of ice,with weaker heat flux through thicker ice.From May onward,FYI and SYI showed a similar growth by 0.5 cm/d.Their maximum thickness reached 160.5 cm and 167.0 cm,respectively,in late October.Drillings showed variations of FYI thickness to be generally less than 1.0 cm,but variations were up to 33.0 cm for SYI in March,suggesting that the SYI bottom was particularly uneven.Snow distribution was strongly affected by wind and surface roughness,leading to large thickness differences in the different sites.Snow and ice thickness in Nella Fjord had a similar“east thicker,west thinner”spatial distribution.Easterly prevailing wind and local topography led to this snow pattern.Superimposed ice induced by snow cover melting in summer thickened multi-year ice,causing it to be thicker than the snow-free SYI.The estimated monthly oceanic heat flux was~30.0 W/m2 in March–May,reducing to~10.0 W/m2 during July–October,and increasing to~15.0 W/m2 in November.The seasonal change and mean value of 15.6 W/m2 was similar to the findings of previous research.The results can be used to further our understanding of landfast ice for climate change study and Chinese Antarctic Expedition services. 展开更多
关键词 landfast ice thickness OCEANIC heat flux PRYDZ BAY East ANTARCTICA
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Comprehensive Disaster Risk Prevention of "the Belt and Road Initiative" : Important Significance, Catastrophe Risk, International Cooperation and Strategic Countermeasure 预览
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作者 Feng KONG 《亚洲农业研究:英文版》 2019年第9期46-50,共5页
"The Belt and Road Initiative"is major decision proposed by the CPC Central Committee with comrade Xi Jinping as the core co-ordinating the domestic and international overall situations,and concerns peaceful... "The Belt and Road Initiative"is major decision proposed by the CPC Central Committee with comrade Xi Jinping as the core co-ordinating the domestic and international overall situations,and concerns peaceful rise of China and extension of the strategic opportunity period of modernization construction.It needs multi-faceted safeguards to successfully impel"the Belt and Road Initiative",in which disaster risk identification and its effective prevention and control are indispensable links.By integrating geogeographic and atmospheric environmental factors,countries along"the Belt and Road Initiative"belong to frequent occurrence region of major natural disasters.It restricts not only the economic and social development of relevant countries but also implementation effect of"the Belt and Road Initiative"construction,and is also related to the success or failure of Chinese enterprises going out to a certain extent.It should enhance disaster prevention and mitigation and ensure safety of major infrastructure construction related to interconnection of"the Belt and Road Initiative"by disaster identification and prevention,which is the key of successfully impelling strategy implementation and major need for guaranteeing the people s livelihood of the countries along the line.The work of disaster prevention and mitigation in the countries along the line is generally weak,and it is urgent to raise the level of disaster prevention as a whole by promoting the disaster prevention and mitigation cooperation in the"the Belt and Road Initiative"area;improve the coverage and level of disaster risk insurance;enhance construction in monitoring and early warning capability of natural disaster;strengthen structural adjustment of economy,industry and land use responding to climate change risks;establish a comprehensive disaster reduction forum of"the Belt and Road Initiative",and contain relevant content in"the Belt and Road Initiative"series of high-end forum topics. 展开更多
关键词 The Belt and Road Initiative Comprehensive disaster prevention and mitigation Catastrophe risk Climate change National security and sustainable development
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Seasonal variation in surface ozone and its regional characteristics at global atmosphere watch stations in China
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作者 Ningwei Liu Weili Lin +2 位作者 Jianzhong Ma Wanyun Xu Xiaobin Xu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第3期291-302,共12页
We investigated the seasonal and spatial ozone variations in China by using three-year surface ozone observation data from the six Chinese Global Atmosphere Watch(GAW)stations and tropospheric column ozone data from s... We investigated the seasonal and spatial ozone variations in China by using three-year surface ozone observation data from the six Chinese Global Atmosphere Watch(GAW)stations and tropospheric column ozone data from satellite retrieval over the period2010–2012. It is shown that the seasonal ozone variations at these GAW stations are rather different, particularly between the western and eastern locations. Compared with western China, eastern China has lower background ozone levels. However, the Asian summer monsoon(ASM) can transport photochemical pollutants from the southern to the northern areas in eastern China, leading to a northward gradual enhancement of background ozone levels at the eastern GAW stations. Over China, the tropospheric column ozone densities peak during spring and summer in the areas that are directly and/or indirectly affected by the ASM, and the peak time lags from the south to the north in eastern China. We also investigated the regional representativeness of seasonal variations of ozone at the six Chinese GAW stations using the yearly maximum tropospheric column month as indicator.The results show that the seasonal variation characteristics of ozone revealed by the Chinese GAW stations are typical, with each station having a considerable large surrounding area with the ozone maximum occurring at the same month. Ozone variations at the GAW stations are influenced by many complex factors and their regional representativeness needs to be investigated further in a broader sense. 展开更多
关键词 Surface OZONE TROPOSPHERIC OZONE COLUMN GAW STATIONS SEASONAL variations Regional REPRESENTATIVENESS
An Analysis of the Discontinuity in Chinese Radiosonde Temperature Data Using Satellite Observation as a Reference
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作者 Yanjun GUO Chengzhi ZOU +1 位作者 Panmao ZHAI Guofu WANG 《气象学报:英文版》 SCIE CSCD 2019年第2期289-306,共18页
Reconciling upper-air temperature trends derived from radiosonde and satellite observations is a necessary step to confidently determine the global warming rate. This study examines the raw and homogenized radiosonde ... Reconciling upper-air temperature trends derived from radiosonde and satellite observations is a necessary step to confidently determine the global warming rate. This study examines the raw and homogenized radiosonde observations over China and compares them with layer-mean atmospheric temperatures derived from satellite microwave observations for the lower-troposphere(TLT), mid-troposphere(TMT), upper-troposphere(TUT), and lower-stratosphere(TLS) by three research groups. Comparisons are for averages over China, excluding the Tibetan Plateau, and at individual stations where metadata contain information on radiosonde instrument changes. It is found that major differences between the satellite and radiosonde observations are related to artificial systematic changes. The radiosonde system updates in the early 2000 s over China caused significant discontinuities and led the radiosonde temperature trends to exhibit less warming in the middle and upper troposphere and more cooling in the lower stratosphere than satellite temperatures. Homogenized radiosonde data have been further adjusted by using the shift-point adjustment approaches to match with satellite products for China averages. The obtained trends during 1979–2015 from the re-adjusted radiosonde observation are respectively 0.203 ± 0.066, 0.128 ± 0.044, 0.034 ± 0.039, and –0.329 ± 0.135 K decade–1 for TLT, TMT, TUT, and TLS equivalents. Compared to satellite trends, the re-adjusted radiosonde trends are within 0.01 K decade–1 for TMT and TUT, 0.054 K decade–1 warmer for TLT, and 0.051 K decade–1 cooler for TLS. The results suggest that the use of satellite data as a reference is helpful in identifying and removing inhomogeneities of radiosonde temperatures over China and reconciling their trends to satellite microwave observations. Future efforts are to homogenize radiosonde temperatures at individual stations over China by using similar approaches. 展开更多
关键词 RADIOSONDE TEMPERATURE HOMOGENIZATION satellite microwave SOUNDING unit China upper air TEMPERATURE TRENDS
Characteristics of Surface Solar Radiation under Different Air Pollution Conditions over Nanjing, China: Observation and Simulation 预览
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作者 Hao LUO Yong HAN +2 位作者 Chunsong LU Jun YANG Yonghua WU 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第10期1047-1059,共13页
Surface solar radiation (SSR) can affect climate, the hydrological cycle, plant photosynthesis, and solar power. The values of solar radiation at the surface reflect the influence of human activity on radiative climat... Surface solar radiation (SSR) can affect climate, the hydrological cycle, plant photosynthesis, and solar power. The values of solar radiation at the surface reflect the influence of human activity on radiative climate and environmental effects, so it is a key parameter in the evaluation of climate change and air pollution due to anthropogenic disturbances. This study presents the characteristics of the SSR variation in Nanjing, China, from March 2016 to June 2017, using a combined set of pyranometer and pyrheliometer observations. The SSR seasonal variation and statistical properties are investigated and characterized under different air pollution levels and visibilities. We discuss seasonal variations in visibility, air quality index (AQI), particulate matter (PM10 and PM2.5), and their correlations with SSR. The scattering of solar radiation by particulate matter varies significantly with particle size. Compared with the particulate matter with aerodynamic diameter between 2.5 μm and 10 μm (PM2.5-10), we found that the PM2.5 dominates the variation of scattered radiation due to the differences of single-scattering albedo and phase function. Because of the correlation between PM2.5 and SSR, it is an effective and direct method to estimate PM2.5 by the value of SSR, or vice versa to obtain the SSR by the value of PM2.5. Under clear-sky conditions (clearness index ≥0.5), the visibility is negatively correlated with the diffuse fraction, AQI, PM10, and PM2.5, and their correlation coefficients are ?0.50,?0.60,?0.76, and ?0.92, respectively. The results indicate the linkage between scattered radiation and air quality through the value of visibility. 展开更多
关键词 surface solar radiation air pollution PARTICULATE MATTER VISIBILITY RADIATIVE transfer
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Aerosol optical properties and the mixing state of black carbon at a background mountainous site in Eastern China
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作者 Liang Yuan Yan Yin +4 位作者 Hui Xiao Jian Hao Kui Chen Xingna Yu Xiaoling Zhang 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第9期21-38,共18页
In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 Mm-1 for scattering coefficient(σsp, neph, 550), hemispheric ... In-situ measurements of aerosol optical properties were conducted at Mt. Huang from September 23 to October 28, 2012. Low averages of 82.2, 10.9, and 14.1 Mm-1 for scattering coefficient(σsp, neph, 550), hemispheric backscattering coefficient(σhbsp, neph, 550), and absorption coefficient(σap, 550), respectively, were obtained. Atmospheric aging process resulted in the increase of σap, 550 but the decrease of the single scattering albedo(ω550) at constant aerosol concentration. However, the proportion of non-light-absorbing components(non-BCs) was getting higher during the aging process, resulting in the increase of aerosol diameter, which also contributed to relatively higher σsp, neph, 550 and ω550. Diurnal cycles of σsp, neph, 550 and σap, 550 with high values in the morning and low values in the afternoon were observed closely related to the development of the planetary boundary layer and the mountain-valley breeze. BC mixing state, represented by the volume fraction of externally mixed BC to total BC(r), was retrieved by using the modified Mie model.The results showed r reduced from about 70% to 50% when the externally mixed non-BCs were considered. The periodical change and different diurnal patterns of r were due to the atmospheric aging and different air sources under different synoptic systems. Local biomass burning emissions were also one of the influencing factors on r. Aerosol radiative forcing for different mixing state were evaluated by a "two-layer-single-wavelength" model,showing the cooling effect of aerosols weakened with BC mixing state changing from external to core-shell mixture. 展开更多
关键词 AEROSOL optical properties Mixing state Direct RADIATIVE FORCING BACKGROUND mountainous SITE Mt.Huang
Analysis of Low-level Temperature Inversions and Their Effects on Aerosols in the Lower Atmosphere 预览
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作者 Jun LI Hongbin CHEN +4 位作者 Zhanqing LI Pucai WANG Xuehua FAN Wenying HE Jinqiang ZHANG 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第11期1235-1250,共16页
High-quality and continuous radiosonde, aerosol and surface meteorology datasets are used to investigate the statistical characteristics of meteorological parameters and their effects on aerosols. The data were collec... High-quality and continuous radiosonde, aerosol and surface meteorology datasets are used to investigate the statistical characteristics of meteorological parameters and their effects on aerosols. The data were collected at the Atmospheric Radiation Measurement Southern Great Plains climate research facility during 2000–15. The parameters and vertical distribution of temperature inversion layers were found to have strong diurnal and seasonal changes. For surface-based temperature inversion (SBI), the mean frequency and depth of temperature inversion layers were 39.4% and 198 m, respectively. The temperature difference between the top and bottom of SBI was 4.8℃, and so the temperature gradient was 2.4℃(100 m)^-1. The detailed vertical distributions of temperature inversion had been determined, and only the temperature inversion layers below 1000 m showed diurnal and seasonal variations. Mean surface aerosol number concentrations increased by 43.0%, 21.9% and 49.2% when SBIs were present at 0530, 1730 and 2330 LST, respectively. The effect of SBI on surface aerosol concentration was weakest in summer (18.1%) and strongest in winter (58.4%). During elevated temperature inversion events, there was no noticeable difference in surface aerosol number concentrations. Temperature differences and temperature gradients across SBIs correlated fairly well with aerosol number concentrations, especially for temperature gradients. The vertical distribution of aerosol optical properties with and without temperature inversions was different. Surface aerosol measurements were representative of the air within (below), but not above, SBIs and EIs. These results provide a basis for developing a boundary layer aerosol accumulation model and for improving radiative transfer models in the lower atmosphere. 展开更多
关键词 temperature INVERSION AEROSOL LOWER ATMOSPHERE VERTICAL distribution
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Impact of Surface Potential Vorticity Density Forcing over the Tibetan Plateau on the South China Extreme Precipitation in January 2008. Part Ⅰ:Data Analysis
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作者 Tingting MA Guoxiong WU +2 位作者 Yimin LIU Zhihong JIANG Jiahui YU 《气象学报:英文版》 SCIE CSCD 2019年第3期400-415,共16页
The external source/sink of potential vorticity (PV) is the original driving force for the atmospheric circulation. The relationship between surface PV generation and surface PV density forcing is discussed in detail ... The external source/sink of potential vorticity (PV) is the original driving force for the atmospheric circulation. The relationship between surface PV generation and surface PV density forcing is discussed in detail in this paper. Moreover, a case study of the extreme winter freezing rain/snow storm over South China in January 2008 is performed, and the surface PV density forcing over the eastern flank of the Tibetan Plateau (TP) has been found to significantly affect the precipitation over South China in this case. The TP generated PV propagated eastward in the middle troposphere. The associated zonal advection of positive absolute vorticity resulted in the increasing of cyclo-nic relative vorticity in the downstream region of the TP. Ascending air and convergence in the lower troposphere developed, which gave rise to the development of the southerly wind. This favored the increasing of negative meridio-nal absolute vorticity advection in the lower troposphere, which provided a large-scale circulation background conducive to ascending motion such that the absolute vorticity advection increased with height. Consequently, the ascending air further strengthened the southerly wind and the vertical gradient of absolute vorticity advection between the lower and middle troposphere in turn. Under such a situation, the enhanced ascending, together with the moist air transported by the southerly wind, formed the extreme winter precipitation in January 2008 over South China. 展开更多
关键词 potential VORTICITY DENSITY (PVD) ABSOLUTE VORTICITY advection TIBETAN Plateau winter precipitation
A Review of Atmospheric Electricity Research in China from 2011 to 2018 预览
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作者 Xiushu QIE Yijun ZHANG 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第9期994-1014,共21页
Atmospheric electricity research has been conducted actively in China,having profited from the development and application of high temporal and spatial resolution lightning detection and location technologies.This pap... Atmospheric electricity research has been conducted actively in China,having profited from the development and application of high temporal and spatial resolution lightning detection and location technologies.This paper reviews the scientific advances made in the field of atmospheric electricity in China from 2011 to 2018,covering the following five aspects:(1)lightning detection and location techniques;(2)discharge processes and parameters associated with rocket-triggered lightning;(3)physical processes in natural lightning and attachment to the ground;(4)lightning activities and charge structure in different thunderstorms;and(5)effects of thunderstorms on the upper atmosphere.In addition,some outstanding questions for future research are outlined. 展开更多
关键词 ATMOSPHERIC ELECTRICITY LIGHTNING THUNDERSTORM LIGHTNING LOCATION TECHNIQUES
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Interdecadal Modulation of AMO on the Winter North Pacific Oscillation-Following Winter ENSO Relationship 预览
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作者 Shangfeng CHEN Linye SONG Wen CHEN 《大气科学进展:英文版》 CSCD 2019年第12期1393-1403,共11页
It is known that the wintertime North Pacific Oscillation (NPO) is an important extratropical forcing for the occurrence of an El Ni-o-Southern Oscillation (ENSO) event in the subsequent winter via the “seasonal foot... It is known that the wintertime North Pacific Oscillation (NPO) is an important extratropical forcing for the occurrence of an El Ni-o-Southern Oscillation (ENSO) event in the subsequent winter via the “seasonal footprinting mechanism ”(SFM). This study reveals that the Atlantic Multidecadal Oscillation (AMO) can notably modulate the relationship between the winter NPO and the following winter ENSO. During the negative AMO phase, the winter NPO has significant impacts on the following winter ENSO via the SFM. In contrast, the influence of the winter NPO on ENSO is not robust at all during the positive AMO phase. Winter NPO-generated westerly wind anomalies over the equatorial western Pacific during the following spring are much stronger during negative than positive AMO phases. It is suggested that the AMO impacts the winter NPO-induced equatorial westerly winds over the western Pacific via modulating the precipitation climatology over the tropical central Pacific and via modulating the connection of the winter NPO with spring sea surface temperature in the tropical North Atlantic. 展开更多
关键词 North Pacific OSCILLATION ENSO ATLANTIC Multidecadal OSCILLATION
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Diagnostic Analysis on Heavy Rain Process of the Northeast-moving Southwest Vortex 预览
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作者 Rao Xiaoqin Wang Shigong 《气象与环境研究:英文版》 CAS 2019年第3期1-10,17共11页
The moving path of southwest vortex and the mechanism of heavy rain in the north were studied in order to find out the forecasting point of the northern heavy rain,so as to improve the forecasting ability of the heavy... The moving path of southwest vortex and the mechanism of heavy rain in the north were studied in order to find out the forecasting point of the northern heavy rain,so as to improve the forecasting ability of the heavy rain disastrous weather.A large-scale heavy rain process in northern China from 18 to 21 July 2010 was diagnostically analyzed using meteorological conventional and intensified observation data and NCEP 1°× 1° reanalysis data.The result showed that the southwest vortex moved northeastward under the guidance of southwest airflow in the periphery of subtropical high,which was the direct influence system of the heavy rainfall.The heavy rainfall occurred on the east side of the symmetrical axis of the 700 hPa low vortex.The southwest jet provided abundant water vapor and potential instability energy for the occurrence of heavy rainfall.The changes of vorticity advection and temperature advection in the lower and middle troposphere were the leading causes of affecting the development and movement of the low vortex.The low vortex moved along the positive vorticity advection increasing region and the warm advection increasing region.The dry and cold air intruded into the low vortex from the middle layer,which promoted the generation and development of the unstable stratification of upper cold and lower warm,and provided unstable and triggering conditions for heavy rain.The water vapor transport from the Yellow Sea and the Bohai Sea was very abundant,and the water vapor flux was very high,reaching 30 g/(s·cm·hPa).It was the main reason for the maximum precipitation in Liaoning Province,which was the farthest from the southwest vortex source.The study deepened the understanding of the structural characteristics of the southwest vortex and revealed the dynamic mechanism of the northeast movement and development of the southwest vortex as well as the cause of rainstorm induced by interaction with other weather systems.It can provide some forecasting ideas and useful references for forecasting the movement 展开更多
关键词 SOUTHWEST VORTEX Northeast-moving Heavy rain VORTICITY advection Temperature advection
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Impact of Surface Potential Vorticity Density Forcing over the Tibetan Plateau on the South China Extreme Precipitation in January 2008. Part Ⅱ:Numerical Simulation
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作者 Jiahui YU Yimin LIU +1 位作者 Tingting MA Guoxiong WU 《气象学报:英文版》 SCIE CSCD 2019年第3期416-432,共17页
The surface air convergence on the eastern flank of the Tibetan Plateau (TP) can increase the in situ surface potential vorticity density (PVD). Since the elevated TP intersects with the isentropic surfaces in the low... The surface air convergence on the eastern flank of the Tibetan Plateau (TP) can increase the in situ surface potential vorticity density (PVD). Since the elevated TP intersects with the isentropic surfaces in the lower troposphere, the increased PVD on the eastern flank of TP thus forms a PVD forcing to the intersected isentropic surface in the boundary layer. The influence of surface PVD forcing over the TP on the extreme freezing rain/snow over South China in January 2008 is investigated by using numerical experiments based on the Finite-volume Atmospheric Model of the IAP/LASG (FAMIL). Compared with observations, the simulation results show that, by using a nudging method for assimilating observation data in the initial flow, this model can reasonably reproduce the distribution of precipitation, atmospheric circulation, and PVD propagation over and downstream of the TP during the extreme winter precipitation period. In order to investigate the impact of the increased surface PVD over the TP on the extreme precipitation in South China, a sensitivity experiment with surface PVD reduced over the TP region was performed. Compared with the control experiment, it is found that the precipitation in the TP downstream area, especially in Southeast China, is reduced. The rainband from Guangxi Region to Shandong Province has almost disappeared. In the lower troposphere, the increase of surface PVD over the TP region has generated an anomalous cyclonic circulation over southern China, which plays an important role in increasing southerly wind and the water vapor transport in this area;it also increases the northward negative absolute vorticity advection. In the upper troposphere, the surface PVD generated in eastern TP propagates on isentropic surface along westerly wind and results in positive absolute vorticity advection in the downstream areas. Consequently, due to the development of both ascending motion and water vapor transport in the downstream place of the TP, extremely heavy precipitation occurs over southern Ch 展开更多
关键词 extreme weather event TIBETAN Plateau potential VORTICITY DENSITY (PVD) surface PVD FORCING numerical simulation
AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING-TIANJIN-HEBEI REGION UNDER CLIMATE CHANGE
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作者 于占江 周伟灿 张晓 《热带气象学报:英文版》 SCIE 2019年第1期82-91,共10页
Based on the measurements obtained at 64 national meteorological stations in the Beijing-Tianjin-Hebei(BTH) region between 1970 and 2013, the potential evapotranspiration(ET0) in this region was estimated using the Pe... Based on the measurements obtained at 64 national meteorological stations in the Beijing-Tianjin-Hebei(BTH) region between 1970 and 2013, the potential evapotranspiration(ET0) in this region was estimated using the Penman-Monteith equation and its sensitivity to maximum temperature(Tmax), minimum temperature(Tmin), wind speed(Vw), net radiation(Rn) and water vapor pressure(Pwv) was analyzed, respectively. The results are shown as follows.(1)The climatic elements in the BTH region underwent significant changes in the study period. Vwand Rndecreased significantly, whereas Tmin, Tmaxand Pwvincreased considerably.(2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwvin the fall and winter and Rnin the spring and summer. On the annual scale,ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmaxand Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwvhad a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing.(3)The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However,increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the'evaporation paradox'phenomenon in the BTH region. 展开更多
关键词 BEIJING-TIANJIN-HEBEI region CLIMATE change potential EVAPOTRANSPIRATION CLIMATIC element sensitivity COEFFICIENT
Air pollution characteristics and their relationship with emissions and meteorology in the Yangtze River Delta region during 2014–2016
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作者 Tao Ma Fengkui Duan +10 位作者 Kebin He Yu Qin Dan Tong Guannan Geng Xuyan Liu Hui Li Shuo Yang Siqi Ye Beiyao Xu Qiang Zhang Yongliang Ma 《环境科学学报:英文版》 SCIE EI CAS CSCD 2019年第9期8-20,共13页
With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relati... With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O3,decreased. Spatially, the PM2.5, PM10, SO2, and CO concentrations were higher in the northern YRD region, and NO2 and O3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM2.5 was the largest contributor to air pollution in the YRD region, followed by O3, PM10, and NO2.However, particulate matter pollution has declined gradually, while O3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM2.5 concentration was inversely related to wind speed, while O3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM2.5, PM10, SO2, NOx, CO, NH3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region. 展开更多
关键词 Air pollution SPATIOTEMPORAL variation METEOROLOGICAL condition Emission INVENTORY Regional transport YANGTZE River Delta
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