Impact of the seasonal variations of composition on the temperature field of Titan’s stratosphere     

Sébastien Lebonnois  Frédéric Hourdin  David Luz 《Icarus》2003,163(1):164-174

We investigate the role of seasonal variations of Titan’s stratospheric composition on the temperature. We use a general circulation model coupled with idealized chemical tracers that reproduce variations of ethane (C₂H₆), acetylene (C₂H₂), and hydrogen cyanide (HCN). Enhancement of the mole fractions of these compounds, at high latitudes in the winter hemisphere relative to their equatorial values, induces a relative decrease in temperature above approximately 0.2 mbar, with a peak amplitude around −20 K, and a relative increase in temperature below, around 1 mbar, with a peak amplitude around +7 K. These thermal effects are mainly due to the variations of the cooling to space induced by the varying distributions. The ethane, acetylene, and hydrogen cyanide variations affect the cooling rates in a similar way, with the dominant effect being due to ethane, though its latitudinal variations are small.  相似文献   

Propagation of Alfvén waves in multi-layer solar atmosphere model     

Li Bo  Wang Shui 《Chinese Astronomy and Astrophysics》2001,25(4):879-455

In this paper, we idealize the actual solar atmosphere as a multi-isothermal-layer system so as to obtain the energy transmittance of the linear Alfvén wave that propagates through such a system in presence of a uniform oblique magnetic filed. The results indicate that the two-layer model is essentially different to the three-layer one. In the two-layer model, the temperature jump acts as a high pass filter. In the three-layer model, resonant transfer will take place and the transmittance undergoes oscillation as the trigonometric function terms dominate its behavior. For actual solar atmosphere, the result reveals that the lower parts of solar atmosphere are more suitable for those Alfvén waves with period of seconds to transfer their energy.  相似文献   

Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission     

David E. Dunn  Lawrence A. Molnar  Imke de Pater 《Icarus》2004,171(1):183-198

We present a new Very Large Array (VLA) image of Saturn, made from data taken in October 1998 at a wavelength of λ3.6 cm. The moderate ring opening angle (B≈15°) allows us to explore direct transmission of microwave photons through the A and C rings. We find a strong asymmetry of photons transmitted through the A ring, but not in the C ring, a new diagnostic of wake structure in the ring particles. We also find a weak asymmetry between east and west for the far side of the ansae. To facilitate quantitative comparison between dynamic models of the A ring and radio observations, we extend our Monte Carlo radiative transfer code (described in Dunn et al., 2002, Icarus 160, 132-160) to include idealized wakes. We show the idealized model can reproduce the properties of dynamic simulations in directly transmitted light. We examine the model behavior in directly transmitted and scattered light over a range of physical and geometric wake parameters. Finally, we present a wake model with a plausible set of physical parameters that quantitatively reproduces the observed intensity and asymmetry of the A ring both across the planet and in the ansae.  相似文献   

A coupled microphysical/radiative transfer model of albedo and emissivity of planetary surfaces covered by volatile ices     

Janusz Eluszkiewicz  Jean-Luc Moncet 《Icarus》2003,166(2):375-384

A new model of albedo and emissivity of planetary surfaces covered by volatile ices in the form of porous slab-like deposits is described. In the model, a radiative transfer model is coupled with a microphysical model in order to link changes in albedo and emissivity to changes in porosity caused by ice metamorphism. Preliminary results for Triton, Pluto, and Io are presented (the martian CO₂ caps will be the subject of a separate publication). The coupled model will aid in the interpretation of ground-based and spacecraft observations and should lead to advances in surface and atmospheric modeling.  相似文献   

南海温跃层基本特征及一维预报模式   总被引：12，自引：1，他引：12       下载免费PDF全文

徐锡祯  邱章  龙小敏 《海洋与湖沼》1993,24(5):494-502

根据现有1907—1990年南海大面调查资料,按1°×1°网格进行逐月的标准水层的温度统计。在此基础上采用3次样条函数的插值方法计算出整个南海温跃层的深度、厚度和强度并予以相应分析。分析表明,南海温跃层主要分为两种类型:第一类为辐射型,主要分布在南海北部的陆架区内,季节变化显著;第二类为不同水体叠置型,主要分布在广大深水区,它长年存在,季节变化较小。一种温跃层的一维积分预报模式,该模式是基于忽略热平流作用和水平热扩散的前提下,从局部热平衡方程出发,建立了受海面热收支及风混合作用下求解温度垂直分布及温跃层的时空变化。在南海北部水深约300m处进行了单站温跃层后报,结果表明,温跃层的深度、厚度和强度的相对误差均在30％以下。  相似文献   

非线性洋面温度反演     

吴雪宝  邱康睦 《海洋预报》1996,13(4):22-26

本文从辐射方程出发，简述洋面温度与亮度温度之间的非线性关系，进行非线性洋面温度反演的方案设计，用正演算法 计算出非线性洋面温度反演公式的回归系数，对样进行检验。  相似文献   

虾蟹海产品香味的前体物质的加热变化     

薛长湖  汪贻生  林洪  楼伟凤 《中国海洋大学学报(自然科学版)》1994,(4)

本文研究了虾蟹海产品香味的前体物质在加热前后的变化。实验结果表明：对虾和蟹肌肉中的糖原和不饱和脂肪酸在加热前后含量下降，糖原是Ｍａｉｌｌａｒｄ反应的基础物质．不饱和脂肪酸是虾蟹肌肉香味中羰基化合物的前体物质。虾蟹肌肉中主要积累的核苷酸成分ＡＭＰ在加热后减少，而肌肉提取物中的游离氨基酸和结合氨基酸，特别是疏水氨基酸含量均增加。  相似文献   

Simulation experiment on hydrocarbon generating potential of various source rocks on the northern margin of the Qaidam Basin,Qinghai, China     

Xin Li  Dongliang Wang  Baoquan Liu  Chunling Ren  Jianying Guo  Xuefeng Su  Jian Wang 《中国地球化学学报》2008,27(4):412-419

The northern margin of the Qaidam Basin is one of the main oil-gas exploration areas in western China, where source rocks are composed mostly of Middle and Lower Jurassic dark mud shale, carbargillite and coal. A large number of subsurface and outcrop samples differing in lithology with different types of organic matter were selected for resource evaluation, research and calculation. And among them, 13 samples were used for simulation experiment on hydrocarbon generating potential of various source rocks. At first, two kinds of heating modes were compared through simulation experiment, including single temperature-step heating and continual heating. Perhaps, the process of hydrocarbon generation and expulsion occurred naturally between a close system and an open system. In addition, the first heating mode was convenient, and all its reaction products were involved in the whole thermal evolution, and the final simulation experimental results were basically in consistency with the natural evolution trend Therefore, the first heating mode was adopted and the hydrocarbon yield of every sample was worked out. According to the type and lithology of organic matter and the hydrocarbon yield of samples for simulation experiment, hydrocarbon generation and expulsion mode with three kinds of lithology and five types of source rock has been established to provide the basis for hydrocarbon generation evaluation, research and resource calculation.  相似文献   

Laser probe Ar/Ar dating: History and development from a technical perspective     

Hironobu Hyodo   《Gondwana Research》2008,14(4):609

The ⁴⁰Ar/³⁹Ar method using a laser probe opened the door to microscale measurements and diffusion profiles frozen in samples. In the first decade since the initial application of a laser for ⁴⁰Ar/³⁹Ar dating in 1973, practical applications have been few. This is due not only to the fact that the laser and vacuum technologies were immature but that mass spectrometry was also in its infancy. In those days, the sensitivity of a mass spectrometer was generally insufficient to measure the small amount of argon degassed from a geological sample by a laser. These problems have subsequently been solved by new technologies. To understand their current status, a brief history of their development is outlined. This outline focuses on the required detection limit in micro scale measurement, practical approaches for accurate measurement are explained through examples in our laboratory specifically relating to the technical aspects of ⁴⁰Ar/³⁹Ar dating.  相似文献   

西安市冬季采暖气象条件分析和预报方法初探   总被引：6，自引：2，他引：6  

庞文保 罗慧李建科  蔡新玲 《气象科技》2005,33(6):505-508512

对西安市冬季采暖气象条件和预报方法进行了研究。根据国家采暖规范结合西安冬季采暖的实际，首先对西安1951年7月到2003年6月历年的逐日气象资料进行了详尽的分析，比较了国家采暖日期相关规范和规定中的3种不同的统计方法，确定了符合西安特点的采暖初终日。充分利用T213数值预报产品，对2002年和2003年两个冬半年的逐日850hPa和500hPa各时次各类气象要素及与之对应的西安各时次实况的气温作了相关分析，建立了回归方程，提出了采暖期及其逐日气温预报。  相似文献