热带气旋“Malakas”与中纬度系统的相互作用及其结构变化     

刘凡  陈华 《气象科学》2019,39(5):666-674

本文利用中尺度数值模式WRF和LAGRANTO轨迹模式对2010年变性台风"Malakas"进行数值模拟和轨迹分析,分析了Malakas在变性过程中与中纬度系统的相互作用,以及在相互作用过程中Malakas的结构变化特征。结果表明:Malakas变性过程经历了三个阶段:(1)高层扰动加强期,高层的正位涡产生的气旋性环流使低层Malakas中心北部的斜压带西侧产生负的温度平流,表现为冷空气的入侵;(2)Malakas和中纬度系统相互作用时期,台风北上导致斜压带出现,深对流的爆发使低层暖湿气流沿着斜压带上升,快速上升气流中的潜热释放导致低PV空气向对流层上部净输送,在其北部高层重新构建出一个脊;(3)Malakas变性成温带气旋,残存的台风内核与斜压带逐渐合并,负的位涡平流带着非绝热外出流驱动了下游最初脊的构建,加速并且固定了中纬度急流,并整体放大了上层Rossby波模式。  相似文献   

太阳辐射管理地球工程对海洋酸化影响的模拟研究     

温作龙  姜玖  曹龙 《气候变化研究进展》2019,15(1):41-53

研究地球工程对海洋酸化的影响对于评估地球工程对全球气候和环境的影响有重要意义。文中使用中等复杂程度的地球系统模式,模拟了典型CO₂高排放情景RCP8.5下,实施太阳辐射管理地球工程对海洋表面的pH和文石（碳酸钙的一种亚稳形态）饱和度的影响,并定量分析了各环境因子对海洋酸化影响的机理。模拟结果表明,在RCP8.5情景下,到2100年,相对于工业革命前水平,全球海洋表面平均pH下降了0.43,文石饱和度下降了1.77。相对于RCP8.5情景,2100年地球工程情景下全球海洋表面平均pH增加了0.003,而文石饱和度降低了0.16。地球工程通过改变溶解无机碳、碱度、温度等环境因子影响海洋酸化。相对于RCP8.5情景,实施地球工程引起的溶解无机碳浓度的增加使pH和文石饱和度均减小,碱度的增加使pH和文石饱和度均增大,温度的降低使pH增大而使文石饱和度减小。总体而言,太阳辐射管理地球工程可以降低全球温度,但无法减缓海洋酸化。  相似文献   

大涡技术对模拟台风眼墙替换过程的影响          下载免费PDF全文

陈小宇  吴立广  李煜斌 《大气科学学报》2019,42(2):161-173

眼墙替换是影响台风强度和内核结构的一种重要过程。本研究在高分辨率的数值理想试验中加入大涡模拟技术,对比分析大涡模拟对眼墙替换过程的影响。结果表明:大涡模拟的加入使得模拟台风的强度和边界层入流增强。整个眼墙替换过程共用时约20～22 h,但大涡模拟试验中外眼墙形成更迅速,同时强度和上升运动偏弱。外眼墙完全取代内眼墙之后的台风强度超过替换过程之前的强度。此外,使用大涡技术可以更好地模拟出眼墙替换过程中内外眼墙之间的moat区下沉运动,结构特征与前人观测中所发现的结构特征一致。因此,在台风数值研究中引入大涡模拟技术,有助于更好地模拟眼墙替换过程中的台风结构特征和变化。  相似文献   

A Numerical Investigation on Microphysical Properties of Clouds and Precipitation over the Tibetan Plateau in Summer 2014     

Jie TANG  Xueliang GUO  Yi CHANG 《Journal of Meteorological Research》2019,(3):463-477

In order to improve our understanding of microphysical properties of clouds and precipitation over the Tibetan Plateau (TP), six cloud and precipitation processes with different intensities during the Third Tibetan Plateau Atmospheric Science Experiment (TIPEX-Ⅲ) from 3 July to 25 July 2014 in Naqu region of the TP are investigated by using the high-resolution mesoscale Weather Research and Forecasting (WRF) model. The results show unique properties of summertime clouds and precipitation processes over the TP. The initiation process of clouds is closely associated with strong solar radiative heating in the daytime, and summertime clouds and precipitation show an obvious diurnal variation. Generally, convective clouds would transform into stratiform clouds with an obvious bright band and often produce strong rainfall in midnight. The maximum cloud top can reach more than 15 km above sea level and the velocity of updraft ranges from 10 to 40 m s-1. The simulations show high amount of supercooled water content primarily located between 0 and -20℃ layer in all the six cases. Ice crystals mainly form above the level of -20℃ and even appear above the level of -40℃ within strong convective clouds. Rainwater mostly appears below the melting layer, indicating that its formation mainly depends on the melting process of precipitable ice particles. Snow and graupel particles have the characteristics of high content and deep vertical distribution, showing that the ice phase process is very active in the development of clouds and precipitation. The conversion and formation of hydrometeors and precipitation over the plateau exhibit obvious characteristics. Surface precipitation is mainly formed by the melting of graupel particles. Although the warm cloud microphysical process has less direct contribution to the formation of surface precipitation, it is important for the formation of supercooled raindrops, which are essential for the formation of graupel embryos through heterogeneous freezing process. The growth of graupel particles mainly relies on the riming process with supercooled cloud water and aggregation of snow particles.  相似文献   

Interannual Salinity Variability in the Tropical Pacific in CMIP5 Simulations     

Hai ZHI  Rong-Hua ZHANG  Pengfei LIN  Peng YU 《大气科学进展》2019,36(4):378-396

Salinity variability and its causes in the tropical Pacific are analyzed using observations, reanalysis products and model simulations. The mixed-layer salinity(MLS) budget analyses from observations and reanalysis products indicate that its interannual evolution is closely related to ENSO and is predominantly governed by surface forcing and surface advection in the western-central equatorial Pacific. It is found that the observed MLS tendency leads Nin?o3.4 by about 12 months due to the effect of negative freshwater flux(evaporation minus precipitation). These observation-based analyses are used to evaluate the corresponding simulation using GFDL-ESM2 M. It is evident that the model can simulate the spatiotemporal variations of MLS with some discrepancies compared to observations. In the warm pool of the equatorial Pacific the MLS tendency in the model is sensitive to ocean dynamics, however model biases cause the tendency to be underestimated. In particular, the freshwater flux is overestimated while the ocean surface zonal current and vertical velocity at the base of the mixed layer are underestimated. Due to model biases in representing the related physics, the effects of surface forcing on the simulated MLS budget are overestimated and those of subsurface and surface advection are relatively weak. Due to weaker surface advection and subsurface forcing than observed, the simulated compensations for surface forcing are suppressed, and the simulated MLS tendency that leads Nin?o3.4 by 8–10 months, which is shorter than the observed lead time. These results are useful for the interpretation of observational analyses and other model simulations in the tropical Pacific.  相似文献   

边界层参数化对海南岛海风环流结构模拟的影响   总被引：2，自引：0，他引：2  

杨秋彦  苗峻峰  王语卉 《热带气象学报》2019,35(2):234-252

利用WRF V3.7详细分析了应用8种边界层参数化方案（YSU、MYNN2.5、MYNN3、ACM2、BouLac、UW、SH、GBM）所模拟的2014年5月25日海南岛海风环流结构的差异,其中YSU、ACM2和SH为非局地闭合方案,MYNN2.5、MYNN3、BouLac、UW和GBM为局地闭合方案。结果表明:对于海风环流水平结构的模拟,15时,YSU、ACM2、BouLac、UW和SH模拟的北部海风较强,SH和GBM的内陆风速偏大。温度与海风发展强度相对应,MYNN2.5与MYNN3模拟的岛屿温度偏低,海陆温差小,海风相对较弱。对于海风环流垂直结构的模拟,09时海风开始,但强度较小,且存在残余陆风,向内陆传播距离较短,YSU、MYNN2.5和SH方案的海风相对较强。12时,海风已呈现出较为清晰的环流结构,YSU和ACM2的海风厚度及向内陆传播距离相对强于其它方案,MYNN3的环流结构则不太明显,且向内陆推进距离短,海风相对较弱。15时,海风发展强盛,MYNN2.5和MYNN3方案模拟的海风垂直强度较小,ACM2方案的海风垂直环流特征最为明显。18时,海风的强度和扰动均有所减弱,ACM2、BouLac和UW的整体海风相对强于其它方案。21时海风已基本转为陆风,BouLac与UW的陆风环流结构最为清晰。位温、水汽及海风垂直环流强度的发展变化与海风的演变过程基本一致。造成ACM2模拟海风偏强的原因是其边界层垂直混合偏强,形成了足够的湍流混合强度所致。对于边界层高度的模拟,ACM2的边界层顶最高,这与此方案所模拟的海风强度偏大相吻合,其它方案的边界层高度与海风强度并不完全一致。   相似文献   

Discussion on “The action of elemental sulfur plus water on 1-octene at low temperatures” by Said-Ahmad et al. (Organic Geochemistry 59, 82–86)     

《Organic Geochemistry》2015

A recent article (Said-Ahmad, W., Amrani, A., Aizenshtat, Z., 2013. The action of elemental sulfur plus water on 1-octene at low temperatures. Organic Geochemistry 59, 82–86) is commented on in this discussion. Radical mechanisms proposed by Said-Ahmad et al. (2013) for the formation of sulfurized and oxidized organic compounds in experiments involving elemental sulfur and 1-octene under aqueous conditions, aimed at investigating the interaction of organic matter and sulfur compounds under geological conditions, are not compatible with their experimental results and other studies. In addition, results from the experiments aimed at demonstrating the role of HO radicals in the formation of oxidized organic compounds were incorrectly interpreted by the authors. In this discussion, alternative mechanisms for the formation of the sulfurized and oxygenated products reported by Said-Ahmad et al. (2013) are proposed.  相似文献   

泥质杂基含量对柴达木盆地昆2井孔隙演化模式影响的压实模拟实验研究     

禚喜准  张林炎  陈骁帅  张姣姣  杨建林  李银川 《地质论评》2015,61(6):1447-1457

随着勘探程度的提高,油气勘探必然向深层延伸。弄清深部储层的孔隙演化规律,提高预测精度,是深入勘探的重要基础。通过对柴达木盆地昆2井岩屑和岩芯样品的系统采集,运用铸体薄片、扫描电镜和测井解释等手段,系统分析了古近系与新近系地层的岩石学、矿物学和储层物性特征,发现泥质杂基含量与砂岩的孔隙演化密切相关。为了正演孔隙的演化过程,运用分选很好的风成石英砂和粒度细小的红色粘土为材料,按照粘土杂基含量为5%、10%、15%、20%,制作了四类石英砂开展模拟实验。松散沉积物的压实模拟,从1.4MPa试验加压到210.4MPa,分别进行了21个循环实验。将实验模拟的结果,与昆2井的岩芯资料进行了对比分析。研究表明,碎屑岩泥质杂基含量越高,初始孔隙度越小,孔隙度衰减越快;泥质含量较低的净砂岩,当上覆压力达到76.5MPa时,颗粒大量破碎并重新排列,导致粒间体积减缩以及少量直线型粒内裂缝出现,储层物性明显变差。压实模拟的实验数据,能够为快速沉降区砂岩的储层质量预测提供依据。  相似文献   

太行山对北京“7.21”特大暴雨的影响及水汽敏感性分析的数值研究   总被引：5，自引：4，他引：1  

王宇虹  徐国强  贾丽红  赵阳 《气象》2015,41(4):389-400

运用GRAPES_Meso模式对2012年7月21—22日发生在北京地区附近的特大暴雨过程进行数值模拟和地形、水汽的敏感性试验。地形敏感性试验发现,在这次特大暴雨过程中,由于太行山北端的阻挡作用,使得气流和水汽辐合、抬升,加强了对流过程;对流层低层山前东南风和西南风、北风的辐合带增大了气旋性涡度,使东移到北京的低涡稳定维持5 h左右,对降水有明显的增幅作用;而且地形起伏和地形海拔高度对降水都有明显增幅作用,地形起伏的增幅作用较地形高度的大。水汽敏感性试验发现在这次特大暴雨过程中,水汽条件较小的变化,会导致水汽输送的明显差异,从而导致降水量显著地改变。  相似文献   

2008年1月贵州冻雨的数值模拟和层结结构分析   总被引：2，自引：0，他引：2  

张昕  高守亭  王瑾 《高原气象》2015,34(2):368-377

针对2008年初发生在贵州地区的严重冻雨过程,分别从环流背景、低空急流和水汽输送条件等方面分析了准静止锋维持的原因,并选取本次灾害最严重的第3次过程为典型个例,利用WRF模式针对准静止锋影响下的贵州冻雨进行数值模拟来研究冻雨的发生机制。模拟结果较好地反映出高低空环流形势场特征,强雨雪降水带的走向、落区,以及地面温度的分布,均与观测基本吻合。通过分析高分辨率模式的模拟结果,揭示了准静止锋上贵州地区冻雨的层结结构特征及云物质在冻雨区的分布特征。研究结果表明,贵州中部的冻雨区除一般的三层结构(包含冰晶层、暖层和冷层)外,还具有典型的两层结构特征,即:高空的固体降水粒子稀少,900~600 h Pa深厚的逆温层和0℃以上的暖层使中低空存在大量液态粒子,下落的液滴经过近地面的浅薄冷层,形成大量过冷却雨滴,而后降落至地面迅速冻结。  相似文献