Modeling thermal deformation of VLBI antennas with a new temperature model

Temperature variations at very long baseline interferometry (VLBI) sites cause thermal deformations of the VLBI antennas and corresponding displacements of the VLBI reference points. The thermal deformation effects typically contain seasonal and daily signatures. The amplitudes of the annual vertical motion of the antenna reference point can reach several millimeters, depending on the design of the antenna structure, on the material, and on the environmental effects such as global station position, station height and climatology effects. Simple methods to correct this effect use the difference of the environmental temperature with respect to a defined reference temperature, the antenna dimensions, the elevation of the antenna, the material of antenna structure. Applying these simple models for thermal deformation in the VLBI data analysis improves the baseline length repeatability by 3.5%. A comparison of these simple models with local thermal deformation measurements at the antennas in Onsala and Wettzell show that the local measurements and the modeled corrections agree well when the temperature of the antenna structure is used, but agree less good when the surrounding air temperatures are used. To overcome this problem we present a method to model temperature penetration into the antenna structures, that allows to model thermal deformation effects that agree with the observed vertical deformation of the Onsala and Wettzell radio telescopes with a root mean square deviation of 0.07 and 0.13 mm, respectively. Possible implementations in the VLBI analysis are presented, and the definition of an adequate reference temperature is discussed.     

山东省近55年夏季降水和平均气温的多时间尺度分析

利用最近55a山东夏季降水和平均气温资料，统计分析了降水和平均气温的变化特征，并用Meyer小波变换方法，对山东省夏季降水和平均气温进行了分析，发现山东夏季降水呈明显下降趋势，气温略呈上升趋势。小波分析显示两者在中短周期上基本一致，即它们的中短周期基本在11a，5～6a和2～3a左右的时间尺度上变动。而这些基本周期正是太阳黑子活动和海气相互作用的周期，说明山东省夏季降水和平均气温的周期变化主要受太阳黑子活动和海-气相互作用的影响。     

潮汐和地震对全球气候变化的影响

2004年12月26日印尼地震海啸后,全球低温冻害和暴雪灾害频繁发生。"潮汐调温说"和"深海巨震降温说"是一种合理的解释。根据"潮汐调温说"和"深海巨震降温说"理论,2005年全球气温将因为印尼地震海啸和强潮汐南北震荡而降低。美国国家航空航天局(NASA)的科学家认为,一个较弱的厄尔尼诺现象和人类排放的温室气体将使2005年成为人类有记载以来最热的一年。事实上,2005年的温度低于1998年。现在,西方科学家也承认了2005—2007年自然气候的变化抵消了全球气候变暖效应这一客观事实。     

A microscale three-dimensional urban energy balance model for studying surface temperatures

A microscale three-dimensional (3-D) urban energy balance model, Temperatures of Urban Facets in 3-D (TUF-3D), is developed to predict urban surface temperatures for a variety of surface geometries and properties, weather conditions, and solar angles. The surface is composed of plane-parallel facets: roofs, walls, and streets, which are further sub-divided into identical square patches, resulting in a 3-D raster-type model geometry. The model code is structured into radiation, conduction and convection sub-models. The radiation sub-model uses the radiosity approach and accounts for multiple reflections and shading of direct solar radiation. Conduction is solved by finite differencing of the heat conduction equation, and convection is modelled by empirically relating patch heat transfer coefficients to the momentum forcing and the building morphology. The radiation and conduction sub-models are tested individually against measurements, and the complete model is tested against full-scale urban surface temperature and energy balance observations. Modelled surface temperatures perform well at both the facet-average and the sub-facet scales given the precision of the observations and the uncertainties in the model inputs. The model has several potential applications, such as the calculation of radiative loads, and the investigation of effective thermal anisotropy (when combined with a sensor-view model).     

住宅侧墙绿化的降温增湿效应研究

对住宅小区的侧墙绿化墙面与裸露墙面温湿度的对比分析发现,侧墙绿化可以有效地改善墙体的温湿度状况;同时通过观测爬墙虎的蒸腾速率,推算出其对环境的降温增湿效果;并通过有侧墙绿化与无侧墙绿化室内温湿度分析比较,说明侧墙绿化对室内温湿度的影响。     

青海高原地区近250 a来年平均气温变化及突变分析

用多条树轮重建的青海高原近250 a平均气温序列,利用线性趋势、小波变换分析和突变检测等方法对近250 a青海高原年平均气温的年际变化及突变特征进行了综合分析,结果表明:250多a来青海高原年平均气温波动明显,30 a滑动平均表现出1779～1811年和1934～2006年年平均气温偏高,其中年平均气温最高出现在1998年为1.3℃,1741～1778年和1812～1933年年平均气温偏低,其中年平均气温最低出现在1823年为-1.5℃,年气温总体呈上升趋势;在20 a以上相对大尺度上,年平均气温冷、暖交替的特征明显,经历了7个冷、暖交替阶段,在2～3 a,28 a左右,48 a和110 a时间尺度上的周期变化都比较明显。     

地面-坑道激电测深方法在山东玲珑断裂带深部找矿中的应用

在山东玲珑断裂带深部找矿中,考虑断裂带处在地电干扰和地形变化复杂地段,且深部地质体产状变化较大,仅依据半空间地面物探方法很难摸清地质体的展布形态,盲目布设钻孔会造成找矿成本的提高。为精确反演深部矿体的边界范围、走向及倾向,提高钻孔见矿率,降低找矿成本,在山东玲珑断裂带地面、坑道采用立体物探技术,试验通过布设多条方位不同的地-坑、坑-坑和地-地纵横激电中梯剖面和双向三极测深剖面,进行了二维电法剖面反演。在地面-坑道激电测深方法中,地面-坑道供电,坑道测量探测深度与坑道深度呈正相关,反映了深部巷道底板以下电阻率和极化率的分布状况,可以实现深地探测目的。由于地面-坑道供电,坑道测量装置处在半空间和全空间两个部分,需要采用"镜像法"和地下倾斜偶极源电流场特征对其装置系数k值重新推导,以反映坑道空间岩矿体真实电阻率的变化。坑道中梯剖面异常与单向三极剖面异常、双向三极电测深反演结果对应较好。经钻探验证,矿体分布与物探推断高极化体基本一致,为快速准确布设深部钻孔提供资料。     

佘山重力垂直梯度偏小的原因及其对大地测量的影响

根据推导的公式计算了由山体质量引起的梯度效应,结果与实测值甚为接近。分析了佘山重力垂直梯度偏小的原因,认为这是由于山体质量分布引起的。最后讨论了垂直梯度偏小对重力值的高度归算和大地水准面的影响。     

红外仪激电仪超前探水技术研究

在１００号矿体工程的斜井开拓中,用构造推断及红外仪激电仪进行超前探水预测预报,经过现场实测、跟踪监测及含水曲线的研究分析,准确预报了前方含水构造部位,防止了水害,加快完成了该矿体的开拓,取得了明显的经济效益。     

槽隆与台向斜构造对比的流体包裹体研究

对槽隆与台向斜这两个不同构造单元的早古生代沉积地层进行了系统的流体包裹体对比研究,阐述了其各自的流体包裹体类型,测定了均一温度,进而探讨了流体包裹体特征所显示的两大构造单元的古地理环境。