青藏高原感热气泵影响亚洲夏季风的机制

本文回顾了二十年来关于青藏高原感热驱动气泵(TP-SHAP)及其影响亚洲夏季风的研究进展,并从能量(θ)、位涡—加热(PV–Q)、和角动量守恒(AMC)的不同角度阐述其影响机制。指出高原斜坡上的表面感热加热改变了移向高原的大气质块的能量从而出现垂直抽吸的重要性。强调了高原加热产生的位涡强迫在近地层制造了强度大范围广的、环绕高原的气旋式环流,把丰沛的水汽从海洋输运到大陆,为季风对流降水提供充足的水汽条件。证明高原加热还通过改变其上空的温、压场的结构从而制造出高原上空近对流层顶的绝对涡度和位涡的最小值,在角动量平衡约束下,在亚洲季风区激发出与Hadley环流反向的季风经圈环流,从而为季风发生发展提供了大范围上升运动的背景。文中还对近年来有关青藏高原影响亚洲夏季风机制的讨论进行概述,并展望了未来的研究方向。     

增强现实地图研究与应用

随着数字地图技术的不断革新,产生了将虚拟信息与真实世界融合的新型地图技术,即增强现实(augmented reality,AR)地图。从可视化、定位、测绘、分析几个方面阐述了AR地图的关键技术,介绍了AR地图的空间映射原理和可视化效果,提出了结合视觉定位和惯导定位的cm级室内定位方法,实现了基于AR地图的AR导航、AR测量、AR目标采集、AR地理围栏等关键技术并将其应用于AR智慧园区与AR室内场馆。     

Seasonal evolution of subtropical anticyclones in the climate system model FGOALS-s2

The simulation characteristics of the seasonal evolution of subtropical anticyclones in the Northern Hemisphere are documented for the Flexible Global Ocean-Atmosphere-Land Systemmodel, Spectral Version 2 (FGOALS-s2), developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, the Institute of Atmospheric Physics. An understanding of the seasonal evolution of the subtropical anticyclones is also addressed. Compared with the global analysis established by the European Centre for Medium-Range Forecasts, the ERA-40 global reanalysis data, the general features of subtropical anticyclones and their evolution are simulated well in both winter and summer, while in spring a pronounced bias in the generation of the South Asia Anticyclone(SAA) exists. Its main deviation in geopotential height from the reanalysis is consistent with the bias of temperature in the troposphere. It is found that condensation heating (CO) plays a dominant role in the seasonal development of the SAA and the subtropical anticyclone over the western Pacific (SAWP) in the middle troposphere. The CO biases in the model account for the biases in the establishment of the SAA in spring and the weaker strength of the SAA and the SAWP from spring to summer. CO is persistently overestimated in the central-east tropical Pacific from winter to summer, while it is underestimated over the area from the South China Sea to the western Pacific from spring to summer. Such biases generate an illusive anticyclonic gyre in the upper troposphere above the middle Pacific and delay the generation of the SAA over South Asia in April. In midsummer, the simulated SAA is located farther north than in the ERA-40 data owing to excessively strong surface sensible heating (SE) to the north of the Tibetan Plateau. Whereas, the two surface subtropical anticyclones in the eastern oceans during spring to summer are controlled mainly by the surface SE over the two continents in the Northern Hemisphere, which are simulated reasonably well, albeit with their centers shifted westwards owing to the weaker longwave radiation cooling in the simulation associated with much weaker local stratiform cloud. Further improvements in the related parameterization of physical processes are therefore identified.     

Dynamical and Thermal Problems in Vortex Development and Movement. Part I: A PV–Q View

Based on the Lagrangian change equation of vertical vorticity deduced from the equation of threedimensional Ertel potential vorticity(PV e),the development and movement of vortex are investigated from the view of potential vorticity and diabatic heating(PV-Q).It is demonstrated that the asymmetric distribution in the vortex of the non-uniform diabatic heating in both vertical and horizontal can lead to the vortex’s development and movement.The theoretical results are used to analyze the development and movement of a Tibetan Plateau(TP) vortex(TPV),which appeared over the TP,then slid down and moved eastward in late July 2008,resulting in heavy rainfall in Sichuan Province and along the middle and lower reaches of the Yangtze River.The relative contributions to the vertical vorticity development of the TPV are decomposed into three parts:the diabatic heating,the change in horizontal component of PV e(defined as PV 2),and the change in static stability θ z.The results show that in most cases,diabatic heating plays a leading role,followed by the change in PV 2,while the change of θ z usually has a negative impact in a stable atmosphere when the atmosphere becomes more stable,and has a positive contribution when the atmosphere approaches neutral stratification.The intensification of the TPV from 0600 to 1200 UTC 22 July 2008 is mainly due to the diabatic heating associated with the precipitation on the eastern side of the TPV when it uplifted on the up-slope of the northeastern edge of the Sichuan basin.The vertical gradient of diabatic heating makes positive(negative) PV e generation below(above) the maximum of diabatic heating;the positive PV e generation not only intensifies the low-level vortex but also enhances the vertical extent of the vortex as it uplifts.The change in PV e due to the horizontal gradient of diabatic heating depends on the vertical shear of horizontal wind that passes through the center of diabatic heating.The horizontal gradient of diabatic heating makes positive(negative) PV e generation on the right(left) side of the vertical shear of horizontal wind.The positive PV e generation on the right side of the vertical shear of horizontal wind not only intensifies the local vertical vorticity but also affects direction of movement of the TPV.These diagnostic results are in good agreement with the theoretic results developed from the PV-Q view.     

夏季青藏高原及周边上对流层水汽质量及其向平流层传输年际异常. I：水汽质量异常主导型

本文利用逐年7~8月平均的ERA-Interim再分析资料并结合SWOOSH(Stratospheric water and ozone satellite homogenized)水汽数据,分析了青藏高原及周边地区330~360 K层次水汽质量分布的年际异常特征及其成因。结果表明,水汽质量分布异常表现为整体异常型、东西偶极异常型和南北偶极异常型三个主导分布型。整体异常型在水汽质量整体偏多时,青藏高原地区对流和垂直向上的水汽质量非绝热传输偏强,上对流层为异常偏强的水汽质量非绝热辐合;此时对应南亚高压偏强,青藏高原地区上对流层的水汽质量绝热辐散和高原以西地区的水汽质量绝热辐合都异常偏强,水汽质量整体偏少时则相反。东西偶极异常型水汽质量呈西多/东少分布时,青藏高原西部(中东部)对流和垂直向上的水汽质量非绝热传输异常偏强(弱),上对流层的水汽质量非绝热辐合和水汽质量绝热辐散也异常偏强(偏弱);同时对应南亚高压偏西,青藏高原以西到伊朗高原的上对流层有异常的自东向西的水汽质量绝热输送和水汽质量绝热辐合。水汽质量呈西少/东多分布时则有相反的结果。南北偶极异常型水汽质量呈北多/南少分布时,对应南亚高压偏北,青藏高原北部的上对流层有异常自南向北的水汽质量绝热输送所造成的水汽质量辐合,同时该地区低层异常偏强的自下向上的水汽质量非绝热输送也加强水汽质量辐合,而青藏高原南侧上对流层则为异常偏弱的水汽质量绝热辐散和水汽质量非绝热辐合,水汽质量呈北少/南多分布时相反。     

ON THE MAINTENANCE OF BLOCKING ANTICYCLONES OF NORTHERN HEMISPHERE—PART I:QUASI-GEOSTROPHIC POTENTIAL VORTICITY ANALYSIS

Four observed blocking anticyclones in different regions of the Northern Hemisphere are in-vestigated.Analyses show that there exist distinct differences in the maintenance of the time-meanquasi-geostrophic potential vorticity(PV)low in 300 hPa within blocking areas.In two Pacificblocking cases,the PV advection by time-mean flow tends to flow the PV low to northwestern partof the blocking highs,and thus is beneficial to the maintenance of the blockings'strength.Thetransfer by transient eddies acts to balance the effect of the time-mean flow.In the Atlantic andAlaska blocking cases,however,the advection of mean flow tends to flow the PV low eastward.The PV transfer by transient eddies acts to flow potential vorticity low to the western part of theblocking ridges and also to balance the time-mean flow's effect.Thus,in the latter two cases,it isthe transfer by the transient eddies that acts to maintain the blockings.     

“核冬天”理论及气溶胶的短波吸收作用

本文扼要回顾了国外关于核爆炸对人类生命、自然环境及气候影响的研究;介绍了近几年关于“核冬天”研究的新成果。通过沙暴尘埃对短波辐射吸收强度的分析,讨论了浓密气溶胶的天气气候效应。     

Progress in the study on the formation of the summertime subtropical anticyclone

The studies in China on the formation of the summertime subtropical anticyclone on the climate timescale are reviewed. New insights in resent studies are introduced. It is stressed that either in the free atmosphere or in the planetary boundary, the descending arm of the Hadley cell cannot be considered as a mechanism for the formation of the subtropical anticyclone. Then the theories of thermal adaptation of the atmosphere to external thermal forcing and the potential vorticity forcing are developed to understand the formation of the subtropical anticyclone in the three-dimensional domain. Numerical experiments are designed to verify these theories. Results show that in the boreal summer, the formation of the strong South Asian High in the upper troposphere and the subtropical anticyclone over the western Pacific in the middle and lower troposphere is, to a great extent, due to the convective latent heating associated with the Asian monsoon, but affected by orography and the surface sensible heating over the continents.On the other hand, the formation of the subtropical anticyclone at the surface over the northern Pacific and in the upper troposphere over North America is mainly due to the strong surface sensible heating over North America, but affected by radiation cooling over the eastern North Pacific. Moreover, in the real atmosphere such individual thermal forcing is well organized. By considering the different diabatic heating in synthesis, a quadruple heating pattern is found over each subtropical continent and its adjacent oceans in summer. A distinct circulation pattern accompanies this heating pattern. The global summer subtropical heating and circulation may be viewed as “mosaics” of such quadruplet heating and circulationpatterns respectively. At last, some important issues for further research in understanding and predicting the variations of the subtropical anticyclone are raised.