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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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THE INTERACTION OF HURRICANE MICHAEL WITH AN UPPER TROUGH LEADING TO INTENSIFICATION RIGHT UP TO LANDFALL
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作者 Jeff Callaghan 《热带气旋研究与评论(英文版)》 2019年第2期101-108,共8页
Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made availab... Hurricane Michael was intensifying as it made landfall devastating areas of the Florida Panhandle including the small town of Mexico Beach. The structure of the hurricane is examined using radar wind data made available from aircraft reconnaissance missions. This showed a dominant warm air advection configuration(winds turning in direction in an anticyclonic fashion with height) around the core of the hurricane. Conventional radiosonde data was also used to study the warm air advection environment east of a deep layered tough system which Michael moved into and which appeared to favour such strong intensification. The structure of this deep trough is also examined and compared with a situation where Hurricane Dennis in 2005 weakened as it approached the coast in much the same region. It appears that the thermal structure of the upper trough at low to middle levels is critical to whether the hurricane intensifies or weakens with the presence of strong cold air advection associated with weakening. 展开更多
关键词 INTENSIFICATION warm AIR advection cold AIR advection upper OUTFLOW deep TROUGH
南海次表层盐度的低频变化及与太平洋年代际振荡的关系 预览
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作者 王祥鹏 张玉红 +2 位作者 王爱梅 赵玮 杜岩 《热带海洋学报》 CAS CSCD 北大核心 2019年第4期1-9,共9页
南海是西北太平洋最大的边缘海,是联系北太平洋和北印度洋的关键通道。黑潮北上经过吕宋海峡时会将来自西太平洋的信号传入南海,进而影响南海的水动力环境。研究了南海次表层盐度的空间分布特征、低频变化规律及其与太平洋年代际振荡(Pa... 南海是西北太平洋最大的边缘海,是联系北太平洋和北印度洋的关键通道。黑潮北上经过吕宋海峡时会将来自西太平洋的信号传入南海,进而影响南海的水动力环境。研究了南海次表层盐度的空间分布特征、低频变化规律及其与太平洋年代际振荡(Pacific Decadal Oscillation, PDO)的关系,并进一步探究了次表层盐度近年来的变化。结果显示:1)南海次表层高盐水的位势密度主要介于24~26σθ,受次表层气旋式环流所驱动,盐度气候态空间分布北高南低,以吕宋海峡处为起点,呈逆时针自北向南逐渐降低。2)次表层盐度低频变化显著,与PDO呈显著的正相关关系。当PDO处于正位相时,吕宋海峡处西向平流输送加强,次表层盐度升高;当PDO处于负位相时,吕宋海峡处西向平流输送减弱,次表层盐度降低,盐度的变化受到水平环流场的直接影响。3)近年来,南海次表层盐度呈现先降低后升高再降低的趋势,滞后PDO约10个月, 2006—2014年初,盐度呈下降趋势;2014—2017年初,盐度呈上升趋势,且上升速率远大于先前下降的速率;2017年后盐度再次逐渐降低。 展开更多
关键词 次表层盐度 低频变化 太平洋年代际振荡 平流输送 南海
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局地水汽异常引起的非绝热加热对2016/2017年中国南方暖冬的影响 预览
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作者 郑彬 黄燕燕 谷德军 《热带气象学报》 CSCD 北大核心 2019年第3期289-295,共7页
基于NCEP/NCAR再分析资料,利用气温异常的倾向方程分析2016/2017年中国华北地区(100~115°E,35~45°N)、西南地区(85~102°E,22~33°N)和南方地区(108~118°E,22~33°N)的暖冬事件。结果表明西南和华北地区的... 基于NCEP/NCAR再分析资料,利用气温异常的倾向方程分析2016/2017年中国华北地区(100~115°E,35~45°N)、西南地区(85~102°E,22~33°N)和南方地区(108~118°E,22~33°N)的暖冬事件。结果表明西南和华北地区的平流作用占主导地位,而2016/2017年冬季中国南方暖冬主要是非绝热加热引起的。进一步通过水汽收支平衡的分析表明,局地水汽异常对2016/2017年中国南方暖冬有重要贡献,而其中土壤的水汽贡献约占50%。可能的机制如下:大气中正的水汽异常引起辐射加热增多,导致气温升高,土壤的感热增大,土壤温度升高,潜热通量变大,从而向大气的水汽输送增多,更多的水汽将导致更高的温度。 展开更多
关键词 暖冬 非绝热加热 平流输送
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Interaction of diabatic processes, large-scale eddies and the mean atmospheric circulation over the Atlantic, Arctic and Eurasia 预览
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作者 Ralf JAISER Dorthe HANDORF Klaus DETHLOFF 《极地科学进展:英文版》 CSCD 2019年第2期81-92,共12页
In the last decade, the atmospheric part of the climate system experienced a shift from pronounced zonal to stronger meridional flow configurations and regionally diverse changes and trends. The climate system shows c... In the last decade, the atmospheric part of the climate system experienced a shift from pronounced zonal to stronger meridional flow configurations and regionally diverse changes and trends. The climate system shows complex interactions and nonlinear behavior, manifested in global warming, rising ocean temperatures and the retreat of Arctic sea ice. Although atmospheric trends and changes are observed, underlying processes are not well understood. In this study we diagnose the interaction of large-scale atmospheric eddies and the mean flow with respect to diabatic heating and cooling processes that impact on the atmospheric advection of heat. For this purpose, three-dimensional Eliassen-Palm flux theory is used in combination with an analysis of the thermodynamic equation, diabatic heating and cooling and heat advection. The most recent decades of observed winter climate are evaluated in terms of climatology and trends over the Atlantic, Arctic and Eurasia. The change of the atmospheric circulation and related processes differ between early and late winter. In early winter, the interaction of macro-turbulent eddies with the mean flow is inhibited at the Atlantic jet stream entrance region and atmospheric heat is meridionally advected into the Arctic, both related to strong high pressure anomalies. In late winter, these anomalies are inverted and a negative phase of the Arctic Oscillation with a more wavy mean flow and a tendency towards stronger meridionalization is observed. 展开更多
关键词 diabatic heating heat advection wave-mean flow interactions North ATLANTIC OSCILLATION ARCTIC OSCILLATION sea ice climate change ARCTIC Amplification polar-mid-latitude linkages
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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
Physical processes causing the formation of hypoxia off the Changjiang estuary after Typhoon Chan-hom,2015 预览
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作者 GUO Yaru RONG Zengrui +3 位作者 LI Bo XU Zhao LI Pixue LI Xiaodan 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2019年第1期1-17,共17页
Severe hypoxia was observed in the submarine canyon to the east of the Changjiang estuary in July 14,2015,two days after typhoon Chan-hom.The oxygen concentration reached as low as 2.0 mg/L and occupied a water column... Severe hypoxia was observed in the submarine canyon to the east of the Changjiang estuary in July 14,2015,two days after typhoon Chan-hom.The oxygen concentration reached as low as 2.0 mg/L and occupied a water column of about 25 m.A ROMS model was confi gured to explore the underlying physical processes causing the formation of hypoxia.Chan-hom passed through the Changjiang estuary during the neap tide.The stratifi cation was completely destroyed in the shallow nearshore region when typhoon passing.However,it was maintained in the deep canyon,though the surface mixed layer was largely deepened.The residual water in the deep canyon is considered to be the possible source of the later hypoxia.After Chan-hom departure,not only the low salinity plume water spread further off shore,but also the sea surface temperature(SST)rewarmed quickly.Both changes helped strengthen the stratifi cation and facilitate the formation of hypoxia.It was found that the surface heat fl ux,especially the solar short wave radiation dominated the surface re-warming,the off shore advection of the warmer Changjiang Diluted Water(CDW)also played a role.In addition to the residual water in the deep canyon,the Taiwan Warm Current(TWC)was found to fl ow into the deep canyon pre-and soon post-Chan-hom,which was considered to be the original source of the hypoxia water. 展开更多
关键词 HYPOXIA CHANGJIANG estuary deep CANYON vertical mixing advection heat fl ux
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The vertical heat transport of internal solitary waves over the continental slope in the northern South China Sea 预览
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作者 Changrong Liang Xiaodong Shang Guiying Chen 《海洋学报:英文版》 SCIE CAS CSCD 2019年第3期36-44,共9页
An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of th... An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of the ISWs. The clusters of ISW packets are phase-locked to the fortnightly cycle of the semidiurnal tide. The ISWs appear during large semidiurnal tides, and there is a period of 5–6 d when no ISWs are observed. The effect of the ISWs on the continental slope heat budget is observed. The ISWs can modify a local temperature field in which the temperature in the upper layer can be changed by O(100) °C after the ISWs passed the mooring. Both ISWinduced diffusion and ISW-induced advection contribute to the temperature variation. The estimates imply an average vertical heat flux of 0.01 to 0.1 MW/m~2 in the ISWs in the upper 500 m of the water column. The vertical heat transport ranges from 0.56 to 2.83 GJ/m~2 with a mean value of 1.63 GJ/m~2. The observations suggest that the vertical heat transport is proportional to the maximum vertical displacement. 展开更多
关键词 internal SOLITARY wave VERTICAL HEAT transport temperature variation DIFFUSION advection VERTICAL HEAT FLUX
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Impact of the Horizontal Heat Flux in the Mixed Layer on an Extreme Heat Event in North China:A Case Study 预览
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作者 Ying NA Riyu LU +2 位作者 Bing LU Min CHEN Shiguang MIAO 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第2期133-142,共10页
Extreme heat over the North China Plain is typically induced by anomalous descending flows associated with anticyclonic circulation anomalies.However,an extreme heat event that happened in the North China Plain region... Extreme heat over the North China Plain is typically induced by anomalous descending flows associated with anticyclonic circulation anomalies.However,an extreme heat event that happened in the North China Plain region on 12–13 July 2015,with maximum temperature higher than 40℃at some stations,was characterized by only a weak simultaneous appearance of an anomalous anticyclone and descending flow,suggesting that some other factor(s)may have induced this heat event.In this study,we used the forecast data produced by the Beijing Rapid Updated Cycling operational forecast system,which predicted the heat event well,to investigate the formation mechanism of this extreme heat event.We calculated the cumulative heat in the mixed-layer air column of North China to represent the change in surface air temperature.The cumulative heat was composed of sensible heat flux from the ground surface and the horizontal heat flux convergence.The results indicated that the horizontal heat flux in the mixed layer played a crucial role in the temporal and spatial distribution of high temperatures.The horizontal heat flux was found to be induced by distinct distributions of air temperatures and horizontal winds at low levels during the two days,implying a complexity of the low-level atmosphere in causing the extreme heat. 展开更多
关键词 EXTREME HEAT North China Plain HORIZONTAL HEAT FLUX sensible HEAT FLUX WARM advection
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A numerical model with Stokes drift for pollutant transport within the surf zone on a plane beach 预览
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作者 Chunping Ren Rongrong Liang +1 位作者 Chong Yu Yuchuan Bai 《海洋学报:英文版》 SCIE CAS CSCD 2019年第9期102-112,共11页
This study examines the effects of Stokes drift on pollutant transport within the surf zone on a plane beach both numerically and experimentally. Firstly, the numerical model is described. The wave-induced current is ... This study examines the effects of Stokes drift on pollutant transport within the surf zone on a plane beach both numerically and experimentally. Firstly, the numerical model is described. The wave-induced current is modeled using the concept of the radiation stress. The wave propagation model is based on the wave energy conservation equation. And the advective diffusion model including the Stokes drift is used to describe the pollutant transport in the surf zone. Model validation was achieved in this case versus an analytical solution for an instantaneous point source in a uniform horizontal flow. This study also describes a laboratory experiment on dye release in the surf zone over a plane beach. We examined the final inclination angle required by a continuously released pollutant plume to reach the shoreline under both cases, and transport velocities in the alongshore and cross- shore directions were estimated by linearly fitting the location of a dye-patch front at different time. Results show that this dye patch moved shoreward with an approximate speed of 0.05 m/s (0.017 m/s) between 10 s and 40 s and 0.001 m/s (0.011 m/s) after 40 s for Case 1 (2). This model was then used to simulate pollutant transport in the surf zone on a plane beach as reproduced in the current experiment. Comparisons between our dye transport experiment and numerical results were then also conducted;the data showed that the numerical results including Stokes drift agreed more closely with experimental results than those without it. The data showed that the pollutant was generally transported obviously shoreward in addition to its expected drift along the shore. We also suggest that Stokes drift plays an important role in pollutant movement in the surf zone, especially shoreward. 展开更多
关键词 NEARSHORE current model STOKES DRIFT advection diffusion DYE release surf zone
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Application of New Type of Detection Data in a Heavy Rainfall Process in Changsha 预览
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作者 Huo Tao Shan Nan +2 位作者 Tang Xiaonan Fan Yu Liu Daxin 《气象与环境研究:英文版》 CAS 2019年第4期37-38,41共3页
Using detection data with high space-time resolution from the wind profile radar and millimeter wave cloud radar of Changsha station, and combining observation data of ground automatic station, heavy precipitation pro... Using detection data with high space-time resolution from the wind profile radar and millimeter wave cloud radar of Changsha station, and combining observation data of ground automatic station, heavy precipitation process in Changsha area from June 29 to July 1, 2017 was analyzed. The results showed that the atmospheric temperature advection was calculated by inversion of wind profile radar data of boundary layer, and it could intuitively analyze changes of atmospheric temperature advection before and after precipitation process. The variation characteristics of intensity, thickness and height of warm and cold advection in the upper and lower levels were highly related to the evolution of the precipitation process. The millimeter wave cloud radar can better reflect the vertical structure and evolution of the cloud over the observatory, and had certain indications for the structure characteristics of cloud before the starting of precipitation. When the strong reflectivity started to approach the ground, it also meant that heavy precipitation began to appear. 展开更多
关键词 WIND profile RADAR MILLIMETER wave CLOUD RADAR Temperature advection
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椒江河口春季悬沙输运特征及通量机制研究 预览
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作者 刘伟 范代读 +1 位作者 涂俊彪 芦军 《海洋地质与第四纪地质》 CSCD 北大核心 2018年第1期41-51,共11页
通过分析2016年3月椒江河口两个定点站位的潮周期水文泥沙观测数据,研究了椒江河口春季悬沙输运特征及通量机制。结果表明,河口内侧站位潮流速大于外侧站位值,两站位垂线平均悬沙浓度分别为0.3~5.8kg/m~3和0.3~1.0kg/m~3。悬沙通量机制... 通过分析2016年3月椒江河口两个定点站位的潮周期水文泥沙观测数据,研究了椒江河口春季悬沙输运特征及通量机制。结果表明,河口内侧站位潮流速大于外侧站位值,两站位垂线平均悬沙浓度分别为0.3~5.8kg/m~3和0.3~1.0kg/m~3。悬沙通量机制分解表明,内侧站以向海的潮泵输沙效应最显著,对单宽输沙量绝对值贡献率为43.9%,其次是向陆的平流和垂向净环流输沙,综合作用下悬沙向陆净输移0.39kg/(m·s);外侧站位以向海的平流输沙为主导作用,贡献率为72.6%,悬沙向海净输移0.10kg/(m·s)。小波分析和频谱分析表明,含沙量、输沙率及流速三者之间存在不同的响应关系,内侧站输沙率主要受流速的影响,而外侧站位则主要受控于悬沙浓度变化。 展开更多
关键词 椒江河口 机制分解 潮泵作用 平流输沙 小波分析
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对流反应扩散方程的波前解 预览
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作者 武红艳 《太原师范学院学报:自然科学版》 2018年第4期26-28,共3页
在反应项是拟单调的条件下,通过定义上下解和构造单调迭代序列,得到对流反应扩散方程波前解的存在性。
关键词 对流 行波解 上下解方法 单调迭代
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Spatially adaptive long-term semi-Lagrangian method for accurate velocity advection
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作者 Takahiro Sato Christopher Batty +1 位作者 Takeo Igarashi Ryoichi Ando 《计算可视媒体(英文版)》 CSCD 2018年第3期223-230,共8页
关键词 流体动画平流格式 轨迹 速度场 压力梯度
Recent Increased Warming of the Alaskan Marine Arctic Due to Midlatitude Linkages 预览
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作者 James E. OVERLAND Muyin WANG Thomas J. BALLINGER 《大气科学进展:英文版》 SCIE CAS CSCD 2018年第1期75-84,共10页
Alaskan Arctic waters have participated in hemispheric-wide Arctic warming over the last two decades at over twotimes the rate of global warming. During 2008-13, this relative warming occurred only north of the Bering... Alaskan Arctic waters have participated in hemispheric-wide Arctic warming over the last two decades at over twotimes the rate of global warming. During 2008-13, this relative warming occurred only north of the Bering Strait andthe atmospheric Arctic front that forms a north-south thermal barrier. This front separates the southeastern Bering Seatemperatures from Arctic air masses. Model projections show that future temperatures in the Chukchi and Beaufort seascontinue to warm at a rate greater than the global rate, reaching a change of +4℃ by 2040 relative to the 1981-2010mean. Offshore at 74~N, climate models project the open water duration season to increase from a current average of threemonths to five months by 2040. These rates are occasionally enhanced by midlatitude connections. Beginning in August2014, additional Arctic warming was initiated due to increased SST anomalies in the North Pacific and associated shiftsto southerly winds over Alaska, especially in winter 2015-16. While global warming and equatorial teleconnections areimplicated in North Pacific SSTs, the ending of the 2014-16 North Pacific warm event demonstrates the importance ofinternal, chaotic atmospheric natural variability on weather conditions in any given year. Impacts from global warming onAlaskan Arctic temperature increases and sea-ice and snow loss, with occasional North Pacific support, are projected tocontinue to propagate through the marine ecosystem in the foreseeable future. The ecological and societal consequences ofsuch changes show a radical departure from the current Arctic environment. 展开更多
关键词 Alaska North Pacific Arctic WARM advection polar VORTEX
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基于卫星和Argo观测的阿拉伯海中北部海表盐度季节和年际变化 预览
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作者 W.N.D.S JAYARATHNA 杜岩 +1 位作者 张玉红 孙启伟 《南京信息工程大学学报:自然科学版》 CAS 2018年第3期311-323,共13页
基于美国国家航天局(NASA)发射的水瓶座(Aquarius/SAC-D)卫星和欧洲航天局(ERA)发射的土壤湿度与海洋盐度(SMOS)卫星的观测资料,以及Argo海表盐度资料,重点分析了阿拉伯海中北部海表盐度的季节和年际变化.年平均情况下,Argo、Aquarius和... 基于美国国家航天局(NASA)发射的水瓶座(Aquarius/SAC-D)卫星和欧洲航天局(ERA)发射的土壤湿度与海洋盐度(SMOS)卫星的观测资料,以及Argo海表盐度资料,重点分析了阿拉伯海中北部海表盐度的季节和年际变化.年平均情况下,Argo、Aquarius和SMOS表现出相似的海表盐度分布形态,均表现了阿拉伯海中北部高达36.5 psu的高盐特征.阿拉伯海中北部海表盐度在2—3月出现最低值,在4月之后快速升高,并在夏季西南季风的成熟阶段达到最高.阿拉伯海中北部海表盐度显著的季节变化与季风风场引起的大量蒸发和平流输送相关.夏季风期间,Ras al Hadd急流将来自阿曼湾的高盐水向东向南输送到阿拉伯海中北部海域,使海表盐度升高并达到最高值;冬季风期间,冬季风环流系统在印度半岛西侧海域形成向北的低盐水输送,造成阿拉伯海中北部海表盐度降低.该低盐水平流在冬季风后期能够影响到阿曼海.阿拉伯海中北部海表盐度年际变化主要与季风驱动的季风环流系统的变化相关,尤其是冬季风期间向北流动的印度西侧沿岸流的强弱与该区域海表盐度年际变化关系密切。 展开更多
关键词 阿拉伯海 海表盐度 季风 平流 蒸发 季节和年际变化
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2016—2017年怀柔区一次持续性雾霾天气过程分析 预览
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作者 沈越婷 《农业灾害研究》 2018年第4期1-3,18共4页
从环流形势、气象要素、地形、近地层平流输送等方面对2016年12月30至2017年1月7日怀柔区出现的一次持续性重污染天气过程的形成及持续原因进行了分析。
关键词 雾霾 重污染 持续 PM2.5 平流输送
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两竞争物种的扩散移流模型 预览
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作者 李丹丹 王阳 李冬梅 《杭州电子科技大学学报》 2017年第4期83-85,共3页
探究了两竞争物种扩散模型.首先假设种群具有相同的随机扩散率和不同的移流系数,其中移流沿一定的梯度,移流系数即为扩散策略.当改变两种群的种间竞争系数时,在两种不同的扩散方式下,得到的相应的半平凡稳定状态均是不稳定的.
关键词 反应扩散模型 移流 竞争 进化稳定策略
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陕西关中持续性雾霾天气的气象条件分析 预览 被引量:7
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作者 刘瑞芳 陈小婷 +1 位作者 姚静 杜川利 《中国农学通报》 2017年第1期82-88,共7页
为有效降低雾霾天气造成的灾害损失,为雾霾天气预报提供可靠依据。笔者利用高空探测、自动站观测、激光雷达等资料,对2013年12月17—25日发生在陕西关中的持续性雾霾天气进行诊断分析。结果表明:此次雾霾天气具有明显的阶段性特征,前... 为有效降低雾霾天气造成的灾害损失,为雾霾天气预报提供可靠依据。笔者利用高空探测、自动站观测、激光雷达等资料,对2013年12月17—25日发生在陕西关中的持续性雾霾天气进行诊断分析。结果表明:此次雾霾天气具有明显的阶段性特征,前期的高低空配置有利于污染物的急剧累积,后期中高空气流较为平直,低层有弱暖平流,地面气压场较弱,有利于雾霾天气的稳定维持;持续性轻雾或霾发生时对湿层厚度要求不高,900 h Pa以下即可,相对湿度在60%~80%之间时,有利于雾霾天气持续;地面风速小,逆温层维持,污染物主要集中在近地层200 m以下,是这次严重雾霾的主要天气特征;涡度平流和总温度平流的垂直分布呈现出有利于雾霾产生和维持的动热力结构:关中地区特殊的地形作用也是雾霾天气易发的一个重要原因。 展开更多
关键词 雾霾 逆温层 地形 平流 边界层高度
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一次黄海入海气旋爆发性发展的诊断分析 预览 被引量:1
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作者 史得道 吴振玲 《海洋预报》 2016年第6期32-39,共8页
对2013年11月一次黄海入海气旋的爆发性发展过程进行了诊断分析,结果显示:此次气旋入海发展过程中始终位于500hPa高空槽前,槽前正涡度平流和强烈暖平流是气旋爆发性发展的主要原因。对流层高层有明显正位涡下传至低层,引起地面气旋... 对2013年11月一次黄海入海气旋的爆发性发展过程进行了诊断分析,结果显示:此次气旋入海发展过程中始终位于500hPa高空槽前,槽前正涡度平流和强烈暖平流是气旋爆发性发展的主要原因。对流层高层有明显正位涡下传至低层,引起地面气旋性涡度发展,对气旋爆发性发展有重要作用;气旋发展过程中始终位于高空急流出口区左侧,高空辐散、低空辐合以及强上升运动提供了气旋发展的动力条件;除了低空急流输送,海洋和大气之间耦合作用为气旋爆发性发展提供了必要的热量输送。 展开更多
关键词 温带气旋 爆发性发展 涡度平流 位涡 暖平流 上升运动
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