Parameterization of the thermal impacts of sub-grid orography on numerical modeling of the surface energy budget over East Asia

Summary A parameterization scheme for the thermal effects of subgrid scale orography is incorporated into a regional climate model (developed at Nanjing University) and its impact on modeling of the surface energy budget over East Asia is evaluated. This scheme includes the effect of terrain slope and orientation on the computation of solar and infrared radiation fluxes at the surface, as well as the surface sensible and latent heat fluxes. Calculations show that subgrid terrain parameters alter the diurnal cycle and horizontal distributions of surface energy budget components. This effect becomes more significant with increased terrain slope, especially in winter. Due to the inclusion of the subgrid topography, the surface area of a model grid box changes over complex terrain areas. Numerical experiments, with and without the subgrid scale topography scheme, show that the parameterization scheme of subgrid scale topography modifies the distribution of the surface energy budget and surface temperature around the Tibetan Plateau. Comparisons with observations indicate that the subgrid topography scheme, implemented in the climate model, reproduces the observed detailed spatial temperature structures at the eastern edge of the Tibetan Plateau and reduces the tendency to overestimate precipitation along the southern coastal areas of China in summer.     

Characteristics of carbonyl compounds in ambient air of Shanghai,China

The levels of carbonyl compounds in Shanghai ambient air were measured in five periods from January 2007 to October 2007 (covering winter, high-air-pollution days, spring, summer and autumn). A total of 114 samples were collected and eighteen carbonyls were identified. Formaldehyde, acetaldehyde and acetone were the most abundant carbonyls and their mean concentrations of 19.40 ± 12.00, 15.92 ± 12.07 and 11.86 ± 7.04 μg m⁻³ respectively, in the daytime for five sampling periods. Formaldehyde and acetaldehyde showed similar diurnal profiles with peak mixing ratios in the morning and early afternoon during the daytime. Their mean concentrations were highest in summer and lowest in winter. Acetone showed reversed seasonal variation. The high molecular weight (HMW, ≥C5) carbonyls also showed obvious diurnal variations with higher concentrations in the daytime in summer and autumn, while they were all not detected in winter. Formaldehyde and acetaldehyde played an important role in removing OH radicals in the atmosphere, but the contribution of acetone was below 1%. The carbonyls levels in high-air-pollution days were reported. More carbonyl species with higher concentrations were found in high-air-pollution days than in spring. These carbonyls were transported with other pollutants from north and northwest in March 27 to April 2, 2007 and then mixed with local sources. Comparing with Beijing and Guangzhou, the concentrations of formaldehyde and acetaldehyde in Shanghai were the highest, which indicated that the air pollution in Shanghai was even worse than expected.     

台风云娜后部强降水分析

通过对中尺度自动站、常规气象要素、1°×1°NCEP格点资料和多普勒雷达资料的诊断分析,发现台风云娜登陆后西行路径对其后部的强降水起了关键性作用;高层辐散和低层辐合差加大,抽吸作用加强,上升运动加剧是后部降水加强的动力原因;沿海较冷的温度场配合台风后部强烈的东南偏南水汽输送,是台风后部降水加强的热力原因;台风后部海面上形成北上的螺旋雨带是造成台风后部强降水的直接原因;浙江东部地形与台风后部强烈的东南偏南水汽输送正交是造成台风后部降水增幅的重要原因。该分析结果对今后台风预报服务实际工作具有一定的参考作用。     

华南区域季节性降水的差异分析

运用EOF方法研究华南区域降水时空分布特征,结果表明：（1）华南地区各季节降水在年际和年代际的时间变化上有区域一致性,但有季节性差异,其中春季和秋季在20世纪80年代后降水明显减少,旱年增多;而夏季90年代后降水明显增加,涝年增多;冬季变化则不明显。（2）华南地区各季节降水在空间分布上也有差异,其中春季降水呈现东多西少的分布特征,大值中心位于广西东北部、广东中部及西南沿海。夏季和秋季降水相似,呈南多北少的分布特征,大值中心位于广西沿海和广东西南沿海。冬季降水呈东北多西南少的分布特征,大值中心位于粤北。     

TVGA图形适配器对多卜勒风速的显示

着重介绍单多卜勒雷达圆锥体扫描获得的风速，回波强度资料在显示之前的数据处理方法，以及用ＴＶＧＡ图形适配器的高分辨显示模式（８００×６００，２５６色）显示多卜勒风场的技术。     

The influence of systematic errors in the Southeast Pacific on ENSO variability and prediction in a coupled GCM

The impact of the warm SST bias in the Southeast Pacific (SEP) on the quality of seasonal and interannual variability and ENSO prediction in a coupled GCM is investigated. The reduction of this bias is achieved by means of empirical heat flux correction that is constant in time. It leads to a wide range of changes in the tropical Pacific climate including enhanced southeast trades, well-defined dry zone in the SEP, better simulation of the South Pacific Convergence Zone and stronger cross-equatorial asymmetry of the mean state in the eastern Pacific. As a result of the mean climate correction, significant improvements in the simulation of the seasonal cycle of the oceanic and atmospheric states are also observed both at the equator and basin-wide. Due to more realistic simulation of the seasonal evolution of the cold tongue, tropical convection and surface winds in the corrected version of the model, phase-lock of ENSO to the annual cycle looses its strong semi-annual component and becomes quite similar to the observed, although the amplitude of ENSO is reduced. Zonal wind stress response to the SST anomalies in the central-eastern Pacific also becomes more realistic. ENSO retrospective forecast experiments conducted with the directly coupled and the flux-corrected versions of the model demonstrate that deficiencies in the seasonal evolution of the cold tongue/Inter-Tropical Convergence Zone complex (that were largely due to the SEP bias in this model) and the related errors in the ENSO phase-lock to the annual cycle can seriously degrade ENSO prediction. By reducing these errors, ENSO predictive skill in the coupled model was substantially enhanced.     

An internal-external optimized convolutional neural network for arbitrary orientated object detection from optical remote sensing images

Due to the bird's eye view of remote sensing sensors, the orientational information of an object is a key factor that has to be considered in object detection. ...     

中国西部地区典型岩质滑坡机理研究

本文根据作者在中国西部地区多年的研究工作实践,对几类典型的大型岩质斜坡变形及失稳机理进行了较为深入的分析,重点阐述了这些大型滑坡形成的地质条件、斜坡变形过程及发生机理的"概念模型",其中包括滑移-拉裂-剪断的三段式模式、挡墙溃决模式、"超级强夯"模式等.这些机理及模式的提出,对这一地区的防灾减灾实践具有一定的指导意义.     

四川九寨黄龙机场高填方地基变形三维动力分析

四川九寨黄龙机场具有高填方、高地震烈度、高海拔等三高的特点,高填方体地基在地震作用下的动力稳定与变形问题成为该机场需着重考虑的主要工程地质问题之一。在对目前各种动力分析方法研究的基础上,选用快速拉格郎日差分分析(FLAC)程序,对该机场元山子沟段高填方地基在地震作用下的变形规律进行了系统地研究,获得了一些有实际意义的认识。