东北地区嵌入对流过程的数值模拟分析     

卫甜  丁亨  邱贵强  樊瑞瑞  姚佳林 《气象与环境学报》2022,38(3):29-36

利用常规气象观测资料、NCEP FNL再分析资料以及中尺度WRF模式的数值模拟结果,对2010年7月1日发生在辽宁地区的一次嵌入对流云的形成、演变过程进行了分析,并对云中微物理特征进行了诊断。结果表明:WRF模式较理想地模拟出了此次对流过程。嵌入对流云是在大气上层分布有成片的层状云,低层有零星的对流泡生成的情况下,随着低层对流泡的不断发展壮大,当其伸展至层云的高度时镶嵌其中而成;嵌入的对流体在随层状云东移的过程中反复进行着并合、分裂过程,而且分裂过程中出现明显的右移性对流体的选择性加强;云系中不仅存在云水直接转化为雨水的暖云降水机制,也存在有播撒—供应的冷云降水机制,且成熟阶段冷、暖云降水机制均较为活跃;物理量场上,低层辐合高层辐散的强度在发展阶段最强,最有利云系的发展。  相似文献   

Calculating the Climatology and Anomalies of Surface Cloud Radiative Effect Using Cloud Property Histograms and Cloud Radiative Kernels     

Chen ZHOU  Yincheng LIU  Quan WANG 《大气科学进展》2022,39(12):2124-2136

Cloud radiative kernels (CRK) built with radiative transfer models have been widely used to analyze the cloud radiative effect on top of atmosphere (TOA) fluxes, and it is expected that the CRKs would also be useful in the analyses of surface radiative fluxes, which determines the regional surface temperature change and variability. In this study, CRKs at the surface and TOA were built using the Rapid Radiative Transfer Model (RRTM). Longwave cloud radiative effect (CRE) at the surface is primarily driven by cloud base properties, while TOA CRE is primarily decided by cloud top properties. For this reason, the standard version of surface CRK is a function of latitude, longitude, month, cloud optical thickness (τ) and cloud base pressure (CBP), and the TOA CRK is a function of latitude, longitude, month, τ and cloud top pressure (CTP). Considering that the cloud property histograms provided by climate models are functions of CTP instead of CBP at present, the surface CRKs on CBP-τ histograms were converted to CTP-τ fields using the statistical relationship between CTP, CBP and τ obtained from collocated CloudSat and MODIS observations. For both climate model outputs and satellites observations, the climatology of surface CRE and cloud-induced surface radiative anomalies calculated with the surface CRKs and cloud property histograms are well correlated with those calculated from surface radiative fluxes. The cloud-induced surface radiative anomalies reproduced by surface CRKs and MODIS cloud property histograms are not affected by spurious trends that appear in Clouds and the Earth's Radiant Energy System (CERES) surface irradiances products.  相似文献   

A Modified Double-Moment Bulk Microphysics Scheme Geared toward the East Asian Monsoon Region     

Jinfang YIN  Donghai WANG  Guoqing ZHAI  Hong WANG  Huanbin XU  Chongjian LIU 《大气科学进展》2022,39(9):1451-1471

Representation of cloud microphysical processes is one of the key aspects of numerical models. An improved double-moment bulk cloud microphysics scheme (named IMY) was created based on the standard Milbrandt-Yau (MY) scheme in the Weather Research and Forecasting (WRF) model for the East Asian monsoon region (EAMR). In the IMY scheme, the shape parameters of raindrops, snow particles, and cloud droplet size distributions are variables instead of fixed constants. Specifically, the shape parameters of raindrop and snow size distributions are diagnosed from their respective shape-slope relationships. The shape parameter for the cloud droplet size distribution depends on the total cloud droplet number concentration. In addition, a series of minor improvements involving detailed cloud processes have also been incorporated. The improved scheme was coupled into the WRF model and tested on two heavy rainfall cases over the EAMR. The IMY scheme is shown to reproduce the overall spatial distribution of rainfall and its temporal evolution, evidenced by comparing the modeled results with surface gauge observations. The simulations also successfully capture the cloud features by using satellite and ground-based radar observations as a reference. The IMY has yielded simulation results on the case studies that were comparable, and in ways superior to MY, indicating that the improved scheme shows promise. Although the simulations demonstrated a positive performance evaluation for the IMY scheme, continued experiments are required to further validate the scheme with different weather events.  相似文献   

Analysis of the Effect of Optical Properties of Black Carbon on Ozone in an Urban Environment at the Yangtze River Delta,China     

Junlin AN  Huan LV  Min XUE  Zefeng ZHANG  Bo HU  Junxiu WANG  Bin ZHU 《大气科学进展》2021,38(7):1153-1164

Black carbon(BC) reduces the photolysis coefficient by absorbing solar radiation, thereby affecting the concentration of ozone(O_3) near the ground. The influence of BC on O_3 has thus received much attention. In this study, Mie scattering and the tropospheric Ultraviolet and Visible radiation model are used to analyze the effect of BC optical properties on radiation. Combined with data of O_3 precursors in Nanjing in 2014, an EKMA curve is drawn, and the variations in O_3 concentration are further investigated using a zero-dimensional box mechanism model(NCAR MM). When O_3 precursors are unchanged, radiation and O_3 show a highly similar tendency in response to changing BC optical properties(R=0.997).With the increase of modal radius, the attenuation of fresh BC to radiation and O_3 first trends upward before decreasing. In the mixing process, the attenuation of BC to radiation and O_3 presents an upward tendency with the increase of relative humidity but decreases rapidly before increasing slowly with increasing thickness of coating. In addition, mass concentration is another major factor. When the BC to PM2.5 ratio increases to 5% in Nanjing, the radiation decreases by approximately 0.13%–3.71% while O_3 decreases by approximately 8.13%–13.11%. The radiative effect of BC not only reduces O_3 concentration but also changes the EKMA curve. Compared with the NOx control area, radiation has a significant influence on the VOCs control area. When aerosol optical depth(AOD) increases by 17.15%, the NOx to VOCs ratio decreases by 8.27%, and part of the original NOx control area is transferred to the VOCs control area.  相似文献   

呼和浩特降雨和降雪过程粒子谱分布特征分析     

李慧  苏立娟  郑旭程  李汉超  李盈盈  张敏  甄林峰 《气象》2021,(1):71-81

为深入了解呼和浩特地区降雨和降雪过程中降水粒子谱的分布特征,利用Parsivel观测数据并结合常规观测资料,对2017—2019年发生在呼和浩特地区的8次降雨过程和10次降雪过程的降水粒子谱进行分析。结果表明:雨滴谱和雪花谱都比较符合Gamma分布,平均降雪谱的峰值直径、峰值浓度以及最大直径均大于平均雨滴谱,降水强度相近时,降雪个例的粒子数浓度和尺度参数均大于降雨个例;Gamma拟合的形状因子(μ)和斜率参数(Λ)在降雨和降雪过程中均满足二项式关系,但雪花尺度的变化范围较大导致降雪的μ-Λ拟合效果略差;雪花的下落速度小于雨滴的下落速度,降雨过程中雨滴的下落速度多集中于2~5 m·s^-1,而降雪过程雪花的下落速度多集中于0.5~2 m·s^-1,呼和浩特地区降雪的雪花下落速度更接近于未结凇或干雪的情况。  相似文献   

Geophysical evidence on segmentation of the Tancheng-Lujiang fault and its implications on the lithosphere evolution in East China     

《Journal of Asian Earth Sciences》2013

The north–south trending Tancheng-Lujiang (Tanlu) fault belt extends from northeast China to the Dabie–Sulu orogenic belt, for a length of more than 3000 km. This fault belt probably has close links with the lithosphere evolution, seismic activity and mineral resource concentration in East China. Surface geological mapping and studies on sedimentation and basin formation have indicated segmentation at the southern, middle and northern domains of the fault. Here we employ geophysical constraints to evaluate these fault segments. Unlike previous geophysical studies focused on laterally varying crust/mantle seismic velocity structure across the fault, in this study we have integrated a variety of geophysical data sets, such as crustal P-wave velocity, earthquake occurrence and released seismic energy, seismogenic layer thickness, surface heat flow and geothermal field, to understand the deep structure and strength of the lithosphere along the Tanlu segmented fault belt. The results demonstrate remarkable crustal-scale north-to-south segmentation this major fault. The geophysical evidence and some geochemical constraints suggest that the Tanlu fault belt probably served as a channel for melt and fluid percolation, and exerted a significant control on the lithosphere evolution in East China.  相似文献   

中国城市体系跨境网络结构特征——基于世界500强企业母子关系分析   总被引：1，自引：0，他引：1  

金钟范 《地域研究与开发》2016,(6):37-41

为了认识中国城市体系跨境网络结构特征,以世界500强企业的母子企业间的内在关系视作城市之间的联系证据,建构中国境内城市与境外城市之2-模网络,从总体网络、内源网络和外源网络3个维度进行分析。结果表明:总体网络区域分布较广而差异大,网络要素总体上呈现位序-规模分布,又不同程度偏离"理想值";外源网络相对内源网络发育,并在城市构成上形成部分差异;外源网络度数中心度、核心-边缘分化特点显著,同时境内的上海、北京、广州、苏州等之间,境外的东京、首尔、新加坡、纽约等之间呈现显著的联系共享特点。  相似文献   

川藏交通干线帕隆藏布段冰碛物特性研究进展     

杨东旭  王军朝  杨栋 《探矿工程》2018,45(8):51-57

作为冰川运动的遗迹,冰碛物由于其宽级配、大孔隙、非均质、渗透性等特点,成为川藏铁路和高速公路帕隆藏布路段规划选线中的一类特殊岩土体,并与藏东南地区的冰川型地质灾害具有关联,使得帕隆藏布流域地质灾害的成因机理及防治研究愈发复杂。本文通过分析近年来国内外学者围绕冰碛物物性特征取得的研究成果,结合实地调查和室内外测试结果,归纳了冰碛物的分布特征、沉积构造、物理性质和工程力学特性,梳理了冰碛物的物理力学研究进展,凝练了帕隆藏布流域冰碛物研究中的3个关键问题,针对性地提出下一步研究思路,旨在为后续的冰碛物研究和川藏交通干线规划与建设管理提供参数依据。  相似文献   

祁连山北阿拉善地体特征及其大地构造演化          下载免费PDF全文

吴晓智  赵玉梅  王桂君  郑民 《地质科学》2016,(2):547-560

祁连山北阿拉善地块在大地构造位置上处于中亚造山带、塔里木板块、祁连山-秦岭造山带和华北板块之间.阿拉善地体在太古代-元古代作为一个相对独立的小地体发育, 其结晶基底岩性与塔里木板块、华北板块存在一定程度差异.受加里东构造运动影响, 板块与地体表现为南聚北散特点; 在中奥陶世早期阿拉善地体与华北板块拼为一体, 进入板块整体演化阶段.中海西构造运动期, 北部早二叠世古亚洲洋关闭, 发育新增地壳, 形成北缘沟弧盆体系; 晚海西构造运动期, 阿拉善地体向南俯冲, 祁连山洋关闭, 地壳增生, 阿拉善地体与塔里木板块、华北板块焊接在一起.新特提斯构造运动对其影响巨大, 南缘表现为"左旋"走滑, 北缘表现为"右旋"走滑, 古生代所形成构造带均受到新生代北东向构造的强烈改造.阿拉善地体频繁的构造运动, 致使其南北部相对稳定的燕山期所形成的煤系中小盆地群(阿拉善-银额盆地群、北山盆地群、河西走廊盆地群、祁连山东部盆地群、祁连山西部盆地群、阿尔金盆地群、柴达木周缘盆地群), 也相应发生快速沉降与快速抬升过程, 后期均遭受强烈改造与破坏, 不仅造就烃源岩欠发育, 就是造成储集层致密, 总体不利于油气的生成、运移、聚集成藏, 油气勘探前景欠佳.  相似文献   

2005年汉中市秋季连阴雨的若干特征   总被引：2，自引：0，他引：2  

杨利霞  杨晓永  王国栋 《山西气象》2006,(3):1-3

利用常规观测资料,对2005年8月15日～16日山西省忻州市局部及中南部分地区强暴雨云团发生发展条件进行了诊断分析。结果表明,稳定少动的副高北侧大尺度冷湿云带前沿易产生中低涡,中低层Q向量辐合使局地次级环流加强,有利于不稳定能量聚积,形成中尺度能量系统,为对流云团发生发展奠定了基础;ST与K指数强度变化伴随强对流云团发生发展过程,并具有明显的中尺度特征及先兆作用;中低层冷湿气流的入侵是触发不稳定能量释放的重要条件。  相似文献