The Atmospheric Oxidation of the HS Radical: Reaction with NO2

The atmospheric reaction between HS and NO₂ was theoretically investigated at 298 K and 1 atm of pressure. Our results show that the first reaction step will lead to the formation of HSNO₂ or HSONO, spontaneously and exothermically. HSONO easily decomposes into HSO + NO. On the other hand, HSNO₂ can hardly dissociate in the reactants, and its isomerization to other adducts is much hindered. Production of HNO + SO and SNO + OH was found to be unfavorable. Thus, the main products would be HSO + NO and HSNO₂, and new investigations focusing on the atmospheric fate of HSNO₂ are suggested. A general discussion of the fate of HS under atmospheric conditions is presented. Recent investigations indicate that NO₂, O₂ and N₂O should be the most important oxidants of HS, while the O₃ influence will not be significant.     

拱星OH脉泽辐射频谱的双峰结构和多重分离的膨胀拱星壳

对一些OH／IR星的拱星OH脉泽的观测结果表明,在双峰结构谱线轮廓上常常可以发现一些小峰叠加在双峰上,即在谱线轮廓的双峰结构中的每个峰是由几个小峰叠加而成的．从脉泽的辐射转移方程和拱星包层的速度结构出发,研究拱星OH脉泽辐射频谱的轮廓特征,提出多重分离的膨胀拱星亮模型,很好地解释了双峰结构的奇特观测现象．     

X-ray emission of OH megamaser galaxies

The properties of OH megamaser galaxies in the x-ray region are discussed. Observational data from the XMM-Newton x-ray satellite are presented for three megamasers, IRAS 01418+1651, IRAS 11010+4107, and IRAS 13218+0552. Based on a sample of OH megamaser galaxies it is shown that the x-ray and OH emission are closely coupled. Megamaser emission also correlates with the column density of the medium and the OH emissivity increases as the square of the column density. The results of this study indicate that in OH megamaser galaxies an active nucleus, x-ray heating of molecules, and saturation of the maser emission can play an important role. In some megamasers, active star formation may be the dominant source. __________ Translated from Astrofizika, Vol. 50, No. 2, pp. 171–182 (May 2007).     

Spatial variability of snowmelt timing from AMSR‐E and SSM/I passive microwave sensors,Pelly River,Yukon Territory,Canada

Spring snow melt run‐off in high latitude and snow‐dominated drainage basins is generally the most significant annual hydrological event. Melt timing, duration, and flow magnitude are highly variable and influence regional climate, geomorphology, and hydrology. Arctic and sub‐arctic regions have sparse long‐term ground observations and these snow‐dominated hydrologic regimes are sensitive to the rapidly warming climate trends that characterize much of the northern latitudes. Passive microwave brightness temperatures are sensitive to changes in the liquid water content of the snow pack and make it possible to detect incipient melt, diurnal melt‐refreeze cycles, and the approximate end of snow cover on the ground over large regions. Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer for EOS (AMSR‐E) passive microwave brightness temperatures (T_b) and diurnal amplitude variations (DAV) are used to investigate the spatial variability of snowmelt onset timing (in two stages, ‘DAV onset’ and ‘melt onset’) and duration for a complex sub‐arctic landscape during 2005. The satellites are sensitive to small percentages of liquid water, and therefore represent ‘incipient melt’, a condition somewhat earlier than a traditional definition of a melting snowpack. Incipient melt dates and duration are compared to topography, land cover, and hydrology to investigate the strength and significance of melt timing in heterogeneous landscapes in the Pelly River, a major tributary to the Yukon River. Microwave‐derived melt onset in this region in 2005 occurred from late February to late April. Upland areas melt 1–2 weeks later than lowland areas and have shorter transition periods. Melt timing and duration appear to be influenced by pixel elevation, aspect, and uniformity as well as other factors such as weather and snow mass distribution. The end of the transition season is uniform across sensors and across the basin in spite of a wide variety of pixel characteristics. Copyright © 2007 John Wiley & Sons, Ltd.     

3D Numerical Simulation Analysis of Passive Drag near Free Surface in Swimming

The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k?ε turbulence closure. The volume of fluid (VOF) method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design (CAID) software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer’s arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.     

滦河流域碳、水循环和能量平衡遥感综合试验总体设计

始于20世纪80年代的系列大型遥感试验开始系统研究地表物质和能量交换过程,对遥感与地球系统科学研究的结合起到重要作用,但是尚无综合利用多源遥感数据解决碳、水、能量循环问题的有效方案。遥感科学国家重点实验室于滦河上游地区组织开展基础性、多学科、多尺度的"碳、水循环和能量平衡遥感综合试验"。本次试验面向地球系统科学对遥感观测的最新要求,以遥感如何服务地—气过程研究为关键科学问题,开展星—机—地多尺度遥感综合观测和地面测量,论证中国自主设计的碳、水、能量相关卫星的技术指标,基于大场景真实结构模拟和多尺度综合观测构建虚拟遥感试验场,验证全波段遥感机理模型和复杂地表辐射传输机理。核心试验区位于地势较为平坦的闪电河流域和地形复杂的小滦河流域。闪电河流域主要地类为农田和草地,开展的试验以水循环和能量平衡遥感综合观测为主。小滦河流域主要地类为森林和草地,以碳循环遥感综合观测为主。两个试验区都开展了系统性的多架次飞行试验,并同步开展地面全波段、主被动协同观测。特别设计了一次长达165 km的大跨度飞行试验,横跨两个试验区,包含了地表类型和海拔高度的逐渐过渡。从2017年的预实验开始,整个试验为期5年。基于科学目标驱动、开放、协作、共享的原则,本次试验吸引了10个大型国家科研项目,4个卫星计划团队,19家单位200人次参加,是中国主导的又一次具有明确科学目标的大型多学科交叉遥感综合试验。     

应用微波遥感数据的东北地区地表温度反演

针对无源微波遥感时间分辨率高可以克服云层影响获取地表温度的问题,该文应用AMSR-E微波亮度温度数据,分别选取了基于发射率估计的单通道反演法和多通道线性拟合法反演东北地区地表温度。在原有方法的基础上提出算法改进:对单通道反演法按照植被生长周期在生长季与非生长季分别建立发射率估计方程,探究各微波通道在每种地表覆被类型的反演能力并组合反演精度最高的通道,将微波极化差异指数作为表征发射率参数加入多通道拟合方程。结果显示,获取的地表温度剔除水体和冰雪无效像元后可用性达到100%,改进后的单通道反演法均方根误差由3.58~4.6降低至2.0~3.1,在75%的区域的误差小于2 K;多通道拟合法的最终均方根误差为2.6~3.5,同样有较高精度且只使用微波亮温数据就能获取地表温度。     

应用于被动氢钟的简单滤波器实现

在被动型氢原子钟数字伺服电路中,使用FPGA对误差信号进行数字信号处理。设计了一种简单的低通滤波器,与传统的FIR滤波器相比,节省了FPGA的使用资源,并且性能优于传统滤波器,能够很好地应用于被动型氢钟。     

海南福基田幔源辉石结构OH与氢氧同位素

采用IR光谱和质谱技术分析了海南福基田幔源巨晶和包体中辉石的结构羟基红外光谱和氢氧同位素。测试的所有巨晶普通辉石和包体中透辉石及顽火辉石均含结构OH,对比印证了国内外同类矿物的红外光谱特征。结构水质量分数分别是:普通辉石87×10-6~389×10-6;透辉石127×10-6~273×10-6;顽火辉石69×10-6~207×10-6。包体中结构水质量分数为1 811×10-6~5 377×10-6,平均为3 133×10-6。包体中辉石的氢氧同位素特征如下:透辉石的δ(D)为-123.17‰,顽火辉石的δ(D)为-132.04‰;透辉石的δ(18O)为5.96‰,顽火辉石的δ(18O)为5.60‰。实验和对比表明,辉石是海南福基田上地幔重要的"水储库",包体未受地壳成分污染,继承和保持了上地幔"富水贫氘"的特征。上述结果为该地区上地幔研究提供了结构水和氢氧同位素的基础资料。     

运用H、O同位素资料分析地下热水的补给来源——以鲁西北阳谷-齐河凸起为例

通过对阳谷-齐河凸起地下热水的化学成分、同位素及其地热地质条件的分析,对这一地区的地下热水的补给来源进行了研究。本区地下热水的δD为-65‰～-80.67‰,δ18O为-9.2‰～-10.2‰,均分布在全球雨水线的附近,说明该区地下热水主要为大气降水成因。济南北地热田地下热水的补给高程为256m,此范围大致相当于济南南部山区及其以南的泰山北麓;聊城东地热田地下热水的补给高程为411m,此范围大致相当于泰山山脉及其周边的中山区。聊城东地热田地下热水的2H过量参数d明显低于济南北地热田,说明聊城东地热田地下热水的补给区比后者更远。