共查询到19条相似文献，搜索用时 125 毫秒
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1 引言对全球碳循环了解得不够 ,导致未来大气ＣＯ2 浓度预测的不确定性增加。人们一直认为 ,陆地生态系统对矿物燃料燃烧所释放的ＣＯ2 有较大的净吸收 ,并用此解释矿物燃料燃烧和森林砍伐导致大气中ＣＯ2 量增加的原因。海洋对大气中ＣＯ2 有吸收作用 ,但观测事实表明两者并不平衡 ,即所谓的“碳损失”现象。现在人们主张用陆地生态系统对矿物燃料燃烧释放出的ＣＯ2 有较大的净吸收来解释这一现象。大气中ＣＯ2 的累积速率存在较大的年际和 10ａ(年代 )际的时间尺度变化 ,我们目前尚不能确切地定量的解释这些观测事实。因为不同的解释意… 相似文献
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大气垂直运动方程若干问题讨论 总被引：5，自引：0，他引：5
本文对大气垂直运动方程的尺度分析和小量可否忽略重新进行了讨论，认为如同存在水平地转平衡一样，在大气垂直方向应当存在垂直地转平衡。并提出在大气垂直方向可能存在更高阶平衡：一级平衡为静力平衡，二级平衡为静力偏差和垂直柯氏力的垂直地转平衡，可能还存在第三级平衡，即垂直地转偏差和重力异常的平衡，最后，重力异常偏差的最级有可能与大气行星波垂直加速度和引潮力垂直分量已处于同一量级。 相似文献
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本文简要介绍了GPS技术推算大气水汽含量的研究成果及应用前景，解释了利用GPS技术推算大气水汽含量的原理和方法，简要介绍了求解干延迟的三种经验公式，对GPS观测数据推算大气水汽总量Wp时存在的几种误差进行了分析。 相似文献
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七月大气环流对南极海冰异常的响应 总被引：2，自引：0，他引：2
本文用一个全球大气九层谱模式，模拟了七月份南极两个不同海区海冰区异常对大气环流的影响。主要讨论了大气环流对南极海冰异常存在的局地性的及全球性的响应。细致分析了二个区域极冰异常导致的南北半球低频波列分布的差异，以及它们对热带区域及亚洲季风区降水、越赤道气流的不同影响。最后则依据我们的模拟结果，讨论了南极海冰异常影响全球大气环流的动力学机制。 相似文献
5.
云层与气溶胶对大气吸收太阳辐射的影响 总被引：3，自引：4，他引：3
云通过辐射过程对地气系统的能量平衡起着特别显著的调节作用 ,是影响天气、气候以及全球变化的重要因子。近年来 ,有云大气对太阳短波辐射的“异常吸收”又成为云—辐射研究中的一个争论热点。有云大气的短波吸收受到多种因素的影响 ,关于这方面的研究还不够充分。本文通过计算 ,从理论上探讨了若干因素的组合对大气吸收的综合影响。在计算中 ,同时考虑了不同太阳辐射波段、不同太阳入射天顶角、不同云顶高度以及不同下垫面的影响 ,并考虑了包含大气分子、气溶胶和云滴的吸收与散射 ,以及在近红外波段大气自身的热辐射等过程 ,阐明了云与气溶胶在不同波段对大气吸收太阳辐射的影响。 相似文献
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本文讨论了夏季纬向不对称气候平均流下通过正压大气内部动力过程建立遥相关型的问题。首先详细描述和讨论了有利发展扰动型的概念及其计算方法。作为对比，对正规模不稳定进行了分析。结果表明，正规模的不稳定增长率很小，难以用于解释遥相关型的发展。而有利发展扰动型的计算分析表明，最有利发展的那些扰动型的振幅增长率同实际大气遥相关型的增长率相一致，并且这些有利发展扰动型都将演变为同实际大气相一致的遥相关型结构。从而提出了，至少部分实际大气遥相关型可以不依赖于异常外源强迫，而仅依赖于大气内部的正压过程即能量转换过程而建立起来。 相似文献
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赤道东太平洋海温异常对夏季东亚大气环流的影响 总被引：2，自引：0，他引：2
采用统计诊断和数值试验方法讨论了赤道东太平洋海温异常对东亚夏季大气环流异常的影响，研究表明赤道东太平洋海温的持续异常，引起南海－菲律宾附近地区对流异常的持续，从而导致东亚大气环流的持续异常；同时指出春季赤道东太平洋海温异常和夏季海温异常对夏季东亚大气环流的影响并非是线性叠加，海温持续性异常对东亚夏季气环流的影响在季节时间尺度上存在非线性相互作用。 相似文献
10.
中纬度北太平洋SST异常与大气环流的关系 总被引：12，自引：2，他引：12
在分析北太平洋（６０°Ｎ～２０°Ｓ）ＳＳＴ距平分布特征的基础上，确定出北太平洋海流区为中纬度北太平洋ＳＳＴ变化最活跃的海区。讨论了该海区ＳＳＴ异常与大气环流的相互关系，并与赤道中、东太平洋ＳＳＴ异常和大气环流的相互影响进行了对比分析，发现北太平洋海流区ＳＳＴ异常时，大气环流存在显著的ＰＮＡ型环流。本文还指出在中纬度北太平洋ＳＳＴ异常与北半球大气环流的相互作用中，大气环流是首先启动的方面。 相似文献
11.
UV attenuation in the cloudy atmosphere 总被引：1，自引：0，他引：1
Jianhui Bai 《Journal of Atmospheric Chemistry》2009,62(3):211-228
Ultraviolet (UV) energy absorption plays a very important role in the Earth–atmosphere system. Based on observational data
for Beijing, we suggest that some atmospheric constituents utilize or transfer UV energy in chemical and photochemical (C&P) reactions, in addition to those which absorb UV energy directly. These constituents are primarily volatile organic compounds
(VOCs) emitted from both vegetative and anthropogenic sources. The total UV energy loss in the cloudy atmosphere for Beijing
in 1990 was 78.9 Wm−2. This attenuation was caused by ozone (48.3 Wm−2), other compounds in the atmosphere (26.6 Wm−2) and a scattering factor (4.0 Wm−2). Our results for a cloudy atmosphere in the Beijing area show that the absorption due to these other compounds occurs largely
through the mediation of water vapor. This fraction of energy loss has not been fully accounted for in previous models. Observations
and previous models results suggest that 1) a cloudy atmosphere absorbs 25∼30 Wm−2 more solar shortwave radiation than models predict; and 2) aerosols can significantly decrease the downward mean UV-visible
radiation and the absorbed solar radiation at the surface by up to 28 and 23 Wm−2, respectively. Thus, quantitative study of UV and visible absorption by atmospheric constituents involved in homogeneous
and heterogeneous C&P reactions is important for atmospheric models. 相似文献
12.
Summary The concept of effective cloud cover, elaborated on the basis of an assumption that changes in the net radiation at the top of the atmosphere are mainly caused by changing cloudiness, has been used to deduce solar surface radiation from satellite data. It has been shown that the method permits a calculation of solar surface absorption distributions that agree well with the results obtained by other authors and that the existing disagreement can be to a great extent ascribed to the differences in the data sets and analysis periods. The method allows use of early satellite measurements to get longer time series of the surface radiation budget. In this study, it has been applied to the Nimbus-7 ERB WFOV data for 1979–1986.The net solar flux at the TOA (top of the atmosphere) can be partitioned into absorption at the surface and within the atmosphere. The geographical distributions of all the three quantities as well as the zonal averages of the surface absorption for January and July have been described. Special objectives of the present study are to estimate the interannual standard deviation for the 8-year period and to analyse the shortwave cloud-radiative forcing distributions at the surface and especially within the atmosphere.The standard deviation of the TOA and the surface solar absorption shows a temporal asymmetry, being much larger in January than in July. Noticeable is the disappearance of the wintertime strong variability over the central Pacific in July. As can be expected, the strong variability areas coincide with the strong variability areas of the cloud amount, showing the values up to 27 Wm–2 at the surface.According to our estimate, the shortwave cloud forcing at the surface is everywhere stronger than that at the TOA, so that the cloud forcing of the atmosphere is negative. This means that in the belt of 58.5° N–58.5° S a cloudy atmosphere absorbs more solar energy than a cloud-free atmosphere. Our mean annual value of the atmospheric cloud forcing for this belt is –11 Wm–2 which is somewhat stronger than that obtained by other investigators. It must be stressed that this value is within the uncertainty limits.Shortwave cloud forcing of the atmosphere is the strongest in the lower latitude areas of heavy cloudiness above the continents and negligible in the midlatitudes in winter. This gives evidence that the value of the shortwave cloud forcing of the atmosphere is modified by a combination of cloud absorption and cloud albedo.With 4 Figures 相似文献
13.
Monte-Carlo method has been applied to investigate the radiance and radiative flux on the horizontallyinhomogeneous ground surface in a cloudy atmosphere.It has been found that the characteristics of theground radiance and flux are significantly changed by clouds.The flux in the quadrant toward the surfacewith higher reflectivity are greater than that toward the surface with lower reflectivity.And the flux variesacross the boundary of the two areas with different surface albedos.The effect of inhomogeneity of the surfacealbedo in a cloudy atmosphere can extend far to 20 km.In addition,the horizontal distribution of the fluxabsorbed by the ground is more homogeneous in a cloudy atmosphere than that in a clear air. 相似文献
14.
It is known that the cloud of expanding explosive gases is formed in the air during the explosion of the charge. This cloud takes a regular spherical shape at a certain distance from the charge, and expanding gases start the eddy-like mixing with the ambient air due to turbulent diffusion and the Richtmyer-Meshkov instability mechanism. The pattern of charge explosion in a cloudy environment does not differ much from the pattern of explosion in the free (cloudless) atmosphere: pressure and temperature jumps in the shock wave at different distances from the center of explosion are almost the same as during the explosion in the free atmosphere. However, the microstructure of the cloudy environment may considerably change during explosion in a cloud. These changes are mainly connected with the evaporation of globules in the shock wave and in the field of emission of explosive gases heated up to high temperature. These two factors may cause the formation of the transiucence zone which is generally spherical. Its radius depends on the charge power and on the water content of the cloudy environment where the charge is exploded. The present paper deals with the calculation of linear dimensions of translucence zones formed by the explosion of the charge with a given power in the cloudy environment. 相似文献
15.
Summary The relationship between surface rainfall rate and sea-surface temperature (SST) over tropical cloudy areas is revisited,
and associated air-sea interaction processes are investigated based on hourly grid simulation data over cloudy areas from
a two-dimensional coupled ocean-cloud resolving atmosphere model. A cloud-weighted data analysis shows that surface evaporation
flux decreases with increasing SST and is one order of magnitude smaller than the residual between moisture convergence and
condensation, playing a negligible role in moisture budget. Moisture convergence determines the surface rainfall rate by determining
vapor condensation and deposition rates. Ocean mixed-layer thermal budget shows that the atmospheric surface flux is a major
process responsible for SST variation while thermal advection and thermal entrainment play a secondary role. The results indicate
that atmospheric impacts on the ocean are important whereas oceanic impacts on the atmosphere are not, in the tropical air-sea
system, on short timescales. Thus, the relationship between surface rainfall rate and SST over tropical cloudy areas is not
physically important. Further estimates indicate that the surface evaporation flux and residual between moisture convergence
and condensation could have the same order of magnitude in daily-mean moisture budget. 相似文献
16.
The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering, and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background clear atmosphere is independent of cloud height and solar zenith angle. That’s to say, the radiation downwelling out of a cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith angle, but not on ground albedo for clouds of not very thin optical depth. 相似文献
17.
A diagnostic study of heat transfer within the lower atmosphere and between the atmosphere and the surface of the Arctic Ocean
snow/ice pack during clear-sky conditions is conducted using data from the Surface Heat Budget of the Arctic Ocean (SHEBA)
field experiment. Surface heat budgets computed for four cloudy and four clear periods show that, while the net turbulent
heat fluxes at the surface are small during the cloudy periods, during the clear-sky periods they are a considerable source
of surface heating, balancing significant portions of the conductive heat fluxes from within the snow/ice pack. Analysis of
the dynamics and thermodynamics of the lower atmosphere during the clear-sky periods reveals that a considerable portion of
the heat lost to the surface by turbulent heat fluxes is balanced by locally strong heating near the atmospheric boundary-layer
(ABL) top due to the interaction of subsiding motions with the strong overlying temperature inversions surmounting the ABL.
This heat is then entrained into the ABL and transported to the surface by turbulent mixing, maintained by a combination of
vertical wind shear and wave-turbulence interactions. The frequency of stable, clear-sky periods, particularly during the
winter, combined with these results, suggests that the downward transfer of heat through the lower atmosphere and into the
surface represents an important component of the heat budgets of the lower atmosphere and snow/ice pack over the annual cycle 相似文献
18.
The purpose of this paper is to present a rigorous derivation of a model equation system for the mass and energy open precipitating atmosphere. The derivation is based on the treatment of the atmosphere in terms of three open thermodynamic subsystems consisting of cloudy air, rain water and snow, respectively. Each of the three subsystems moves with a different velocity as caused by the different fall velocities of rain and snow in comparison to the cloudy air.A basic assumption of the model consists in the neglect of the inertia terms in the momentum equation of the falling hydrometeors. It will be shown that this simplification yields additional source terms in the budget equations of the total momentum and the total kinetic energy of the system. However, the prognostic equations for the atmospheric wind field and the corresponding kinetic energy equation remain free of these source terms. The model equations strictly conserve the total mass and energy of the system. It is concluded that the combination of the barycentric velocity of the cloudy air and the total density of the system is the best choice to describe the time evolution of the atmospheric wind field. 相似文献
19.
东亚地区大气辐射能收支(三)--云天大气的地气系统热量收支 总被引：5，自引：2，他引：5
本文是东亚地区大气辐射能收支”的第三部分,讨论了如下几个问题: 1.云天大气长波辐射和辐射差额分布。结果指出,除7月份西藏高原地区外,云天和晴天长波辐射分布特征基本相同,而其辐射差额分布又和相应月份的大气长波辐射分布特征基本一致。 2.东亚地区对流层大气热源热汇分布:8月份整个东亚地区都是冷源,在新疆地区和中国东部北纬32°—25°之间有两个冷中心。在7月份整个东亚地区都是热源,在西藏高原东南部有一个最强的热源中心。新疆北部有一个小的热源中心。 3.东亚各地区的地气系统各种热量收支。首先就整个东亚地区地气系统而言,7月份得到热量基本上补偿了1月份损失的热量,但就大气而言,1月份热量损失大于7月份热量的获得。其次各地区各种热量收支特征并不一致。 相似文献