共查询到20条相似文献，搜索用时 62 毫秒
1.
Chong Shi Pucai Wang Teruyuki Nakajima Yoshifumi Ota Saichun Tan Guangyu Shi 《大气科学进展》2015,32(9):1186-1196
Based on a vector radiative transfer model of the atmosphere-ocean system, the influence of oceanic components on radiation processes, including polarization effects, was investigated in the wavelength region ranging from 0.380 to 0.865 μm. The components considered were phytoplankton, inorganic suspended material (sediment), and colored, dissolved organic matter. Due to their important roles in oceanic radiation processes, the sensitivity of the bidirectional reflectance to the rough ocean surface, represented by the wind velocity 10 m above the ocean surface, and aerosol, were taken into account. The results demonstrated that both radiance and polarized radiance just below the ocean surface were sensitive to the change of the concentrations of the considered components, while the dependence of polarized radiance on the observation geometry was more sensitive than radiance. Significant differences in the specular plane existed between the impacts of the phytoplankton and sediment on the degree of polarization just above the ocean surface at 670 nm. At the top of the atmosphere (TOA), polarization was relatively insensitive to changing concentrations of ocean particles at longer wavelengths. Furthermore, the radiance at the TOA in the solar plane was more sensitive to the aerosol optical thickness than wind velocity. In contrast, wind velocity strongly influenced the radiance at the TOA in the sun glint region, while the polarization degree showed less dependence in that region. Finally, a nonlinear optimal inversion method was proposed to simultaneously retrieve the aerosol and wind velocity using radiance measurement. 相似文献
2.
针对2001年春季中国沙漠和北太平洋上空沙尘气溶胶的空间分布情况，利用辐射传输模式，分别计算了沙尘气溶胶对沙漠和海洋大气的辐射加热（冷却）率，并讨论了低云、中云、高云对辐射加热率的影响。结果表明:春季，位于中国沙漠和太平洋上空的沙尘层对大气具有明显的加热作用。当沙漠上空光学厚度为1.0，海洋上空光学厚度为0.3时，取春季平均太阳高度角，沙尘层对应的净辐射加热率分别为2.8 K/d和0.4 K/d。由于WMO推荐的沙尘模型比东亚沙尘模型对太阳辐射吸收强，采用该模型计算得到的中国沙漠和海洋上空的加热率比采用东亚沙尘模型分别高1.5 K/d和0.2 K/d。沙尘对大气的加热率很大程度上依赖于沙尘的大气载荷。这种依赖性首先受太阳高度角的影响， 其次也受地表反照率的影响。云对沙尘层辐射加热（冷却）率的影响与云的高度和厚度有关。低云能够加热沙漠和海洋上空的沙尘大气，冷却地面和洋面。中、高云冷却沙漠上空的沙尘层。在海洋上空，中云对云层以上的沙尘层有加热作用，对云层以下的沙尘层有冷却作用。高云对海洋上空沙尘层的辐射加热（冷却）率的影响比较小，加热还是冷却，取决于云的厚度，当云层较薄时，加热沙尘层，而当云层较厚的时候，有可能冷却沙尘层。 相似文献
3.
A case study was performed in Beijing in 2000 to observe concentrations of SO2 and NOx in the atmosphere and to evaluate their radiative impact. It was found that the concentrations of these gases are usually high in the morning due to a temperature inversion in the boundary layer. The average concentrations obtained from the observations are much higher than those used in the McClatchey reference atmosphere. The radiative impacts of these gases are calculated using a line-by-line radiative transfer model. The results show that the radiative forcing at the surface due to SO2 is 0.0576 W m-2 and that due to NOx is 0.0032 W m-2. These figures are almost compatible with that due to CFC11. 相似文献
4.
在考虑到大气中各种非绝热加热和对海洋的反馈过程后,建立了一个纬向平均的海洋、大气耦合系统模型。对系统的频率分析表明:存在着一类周期在月以上的长周期振荡。周期的长短依赖于海洋的混合层深度、所在纬度和各种物理过程(如对流凝结加热,辐射冷却、海面蒸发、海水上翻和云量对辐射平衡的调节等)的强弱。 在上述的基础上,讨论了赤道辐合带的形成和变化。计算所得的辐合带宽度和纬度与观测事实是比较一致的。 相似文献
5.
From the viewpoint of earth system science, this paper discusses the observation capability of the second-generation of Chinese polar-orbiting, sun-synchronous operational meteorological satellite observation systems, Fengyun-3(FY-3), based on the function and performance test results from the FY-3 D satellite observation system in orbit. The FY-3 series of satellites have numerous remote sensing instruments and a wide range of imaging and sounding electromagnetic spectrometers onboard. These instruments can obtain reflectivity data for land surface, soil, vegetation,water body, snow cover, ocean color, and sea ice on earth's surface over a wide spectral range, as well as information on the absorption and scattering radiative transfer of molecules and particles(clouds and aerosols) in earth's atmosphere. All of these data can be used to retrieve physical and chemical information about the land, ocean, and atmosphere of the earth system. Comprehensive observation of the earth system by the FY-3 meteorological satellites is preliminarily realized. 相似文献
6.
Physical processes responsible for tropospheric adjustment to increasing carbon dioxide concentration are investigated using abrupt CO2 quadrupling experiments of a general circulation model (GCM) called the model for interdisciplinary research on climate version 5 with several configurations including a coupled atmosphere–ocean GCM, atmospheric GCM, and aqua-planet model. A similar experiment was performed in weather forecast mode to explore timescales of the tropospheric adjustment. We found that the shortwave component of the cloud radiative effect (SWcld) reaches its equilibrium within 2 days of the abrupt CO2 increase. The change in SWcld is positive, associated with reduced clouds in the lower troposphere due to warming and drying by instantaneous radiative forcing. A reduction in surface turbulent heat fluxes and increase of the near-surface stability result in shoaling of the marine boundary layer, which shifts the cloud layer downward. These changes are common to all experiments regardless of model configuration, indicating that the cloud adjustment is primarily independent of air–sea coupling and land–sea thermal contrast. The role of land in cloud adjustment is further examined by a series of idealized aqua-planet experiments, with a rectangular continent of varying width. Land surface warming from quadrupled CO2 induces anomalous upward motion, which increases high cloud and associated negative SWcld over land. The geographic distribution of continents regulates the spatial pattern of the cloud adjustment. A larger continent produces more negative SWcld, which partly compensates for a positive SWcld over the ocean. The land-induced negative adjustment is a factor but not necessary requirement for the tropospheric adjustment. 相似文献
7.
The present work analyzes the effect of aerosols on the evolution of the atmospheric boundary layer (ABL) over Shangdianzi in Beijing.A one-dimensional ABL model and a radiative transfer scheme are incorporated to develop the structure of the ABL.The diurnal variation of the atmospheric radiative budget,atmospheric heating rate,sensible and latent heat fluxes,surface and the 2 m air temperatures as well as the ABL height,and its perturbations due to the aerosols with different single-scattering albedo (SSA) are studied by comparing the aerosol-laden atmosphere to the clean atmosphere.The results show that the absorbing aerosols cause less reduction in surface evaporation relative to that by scatting aerosols,and both surface temperature and 2 m temperature decrease from the clean atmosphere to the aerosol-laden atmosphere.The greater the aerosol absorption,the more stable the surface layer.After 12:00 am,the 2 m temperature increases for strong absorption aerosols.In the meantime,there is a slight decrease in the 2 m temperature for purely scattering aerosols due to radiative cooling.The purely scattering aerosols decrease the ABL temperature and enhance the capping inversion,further reducing the ABL height. 相似文献
8.
利用毫米波云雷达、微波辐射计联合反演方法,对2015年11月11日安徽寿县的一次层状云过程的云参数进行了反演,将所得云参数加入到SBDART辐射传输模式中,进行辐射通量计算,并将计算的地面辐射通量与观测的地面辐射通量进行了对比分析。研究表明:1)利用毫米波雷达和微波辐射计数据联合反演的云参数比较可靠;2)利用SBDART模式并结合反演的云参数,可以准确实时地计算地面及其他高度层的长短波辐射通量;3)在反演的云参数中,光学厚度对地面各种辐射通量的影响是最大的,云层的光学厚度越大,到达地面的太阳短波辐射越小,地面反射短波辐射也越小。另外云底温度越高,云体向下发射的红外长波辐射越大。地面向上的长波辐射是地面温度的普朗克函数,随地面温度而变;4)云对地面的短波辐射强迫为负值,对地面有降温的作用。云对地面的长波辐射强迫是一个正值,对地面有一个增温的作用;5)云对地面的净辐射强迫随时间变化很大,它的正负与太阳高度角和云参数有关。 相似文献
9.
ZHOU Wenyan GUO Pinwen LUO Yong Kuo-Nan LIOU Yu GU Yongkang XUE 《Acta Meteorologica Sinica》2009,23(1):105-115
Accurate estimates of albedos are required in climate modeling. Accurate and simple schemes for radiative transfer within canopy are required for these estimates, but severe limitations exist. This paper developed a four-stream solar radiative transfer model and coupled it with a land surface process model. The radiative model uses a four-stream approximation method as in the atmosphere to obtain analytic solutions of the basic equation of canopy radiative transfer. As an analytical model, the four-stream radiative transfer model can be easily applied efficiently to improve the parameterization of land surface radiation in climate models. Our four-stream solar radiative transfer model is based on a two-stream short wave radiative transfer model. It can simulate short wave solar radiative transfer within canopy according to the relevant theory in the atmosphere. Each parameter of the basic radiative transfer equation of canopy has special geometry and optical characters of leaves or canopy. The upward or downward radiative fluxes are related to the diffuse phase function, the G-function, leaf reflectivity and transmission, leaf area index, and the solar angle of the incident beam. The four-stream simulation is compared with that of the two-stream model. The four-stream model is proved successful through its consistent modeling of canopy albedo at any solar incident angle. In order to compare and find differences between the results predicted by the four- and two-stream models, a number of numerical experiments are performed through examining the effects of different leaf area indices, leaf angle distributions, optical properties of leaves, and ground surface conditions on the canopy albedo. Parallel experiments show that the canopy albedos predicted by the two models differ significantly when the leaf angle distribution is spherical and vertical. The results also show that the difference is particularly great for different incident solar beams. One additional experiment is carried out to evaluate the simulations of the BATS land surface model coupled with the two- and four-stream radiative transfer models. Station observations in 1998 are used for comparison. The results indicate that the simulation of BATS coupled with the four-stream model is the best because the surface absorbed solar radiation from the four-stream model is the closest to the observation. 相似文献
10.
利用TRMM/TMI资料反演青藏高原中部土壤湿度 总被引：2，自引：0，他引：2
用辐射传输理论提出的地表微波辐射极化指数PI的定义,分别指出了PI对土壤湿度、地面粗糙度、植被层和大气层的影响。用热带降水测量(TRMM—Tropical Rainfall Measuring Mission)卫星上携带的微波辐射仪(TMI—TRMM Microwave Imager)的1B11的6年亮温数据,统计得到青藏高原中部地区PI值月平均分布。并用归一化距平,反演得到了该区域年、季以及干湿季土壤湿度变化的空间图像。结果表明,PI距平分布图可以很好地表征土壤湿度的变化,从而为大尺度评估高原土壤湿度变化提供了理论依据。另外,在同一时间段内,在已知区域平均PI值与平均土壤湿度的条件下,用归一化距平的方法可以定量反演该区域的土壤湿度。 相似文献
11.
Based on Successive Order of Scattering approach, a full Vector Radiative Transfer model (SOSVRT) for vertically inhomogeneous plane-parallel media has been developed. To overcome computational burden of convergence, a simple approximation technique by truncating scattering orders with a geometry serial is used to reduce computational time. Analytical Fourier decomposition of phase matrix with three symmetry relationships and two mutual inverse operators has been implemented to further improve the computation efficiency. To improve the accuracy, a post-processing procedure is implemented to accurately interpolate the Stokes vector at arbitrary angles. Comparisons with the benchmarks for an atmosphere of randomly orientated oblate spheroids show excellent agreement for each stokes parameter (within 0.1%). SOSVRT has been tested for different atmospheric condition against RT3, which is based on doubling-adding method, the results approve that SOSVRT is accurate and much more efficient in vector radiative transfer modeling, especially for optical thin atmosphere, which is the most cases in polarized radiative transfer simulation. SOSVRT is written in fortran 90 and the code is freely accessible by contacting the author. 相似文献
12.
本模式为针对大气环流模式所发展的一个简单的陆面过程模式，它包含:（1）地表温度计算，（2）冠层叶面贮水量和土壤湿度计算，（3）陆面与大气之间的水分和能量交换。对于表面温度和含水量的计算，采用的是联立求解计算方案，即耦合计算。植被冠层叶面的辐射特性和冠层形态对冠层中的辐射交换的影响得到有效和尽可能简单的模拟。另外，植被的气孔阻抗、表面与大气之间的水热交换通量和土壤中的水热输导作了较为细致的描写。利用此模式开展了对两个不同覆盖类型的陆面过程的模拟，模拟和观测的表面通量、温度和湿度较为相近。 相似文献
13.
太原城市下垫面扩张对边界层特征影响的个例研究 总被引：1，自引：0，他引：1
通过高分辨率卫星夜间灯光数据获取最新的城市地表分布,并利用高分辨率数值模式对2013年8月14~16日太原区域的一次高温过程进行研究,探讨城市下垫面扩张对大气边界层的影响。结果表明：基于DMSP/OLS夜间灯光数据对模式中地表参数修正后,能够更准确地反映太原主城区和高速公路沿线小规模建筑群的扩张,有效改善了模式的预报性能,显著提高对近地面气温、地表温度的预报能力。城市下垫面的扩张,使城区夜间升温明显,热岛强度增强。与1992年的城市化状况相比,晴空天气条件下,2012年太原城区夜间气温上升5℃,热岛强度升高2~3℃。城市下垫面扩张,改变了地表能量分配关系,使得地表感热传输明显加强,潜热通量明显减弱,城市冠层作用下的储热能力增强。边界层内部湍流交换、水汽输送等的进一步研究表明：城市地表水汽输送减弱,边界层水汽含量减少,2~4 km高度的水汽含量增加,湍流动能的影响高度增高,湍流混合加剧;14：00,城区边界层高度抬高了800 m,城市上空混合层加深,持续时间更长。 相似文献
14.
The effects of an air-temperature inversion in the atmosphere and a seawater density jump in the ocean on the structure of the atmospheric and oceanic boundary layers are studied by use of a coupled model. The numerical model consists of a closed system of equations for velocities, turbulent kinetic energy, turbulent exchange coefficient, local turbulent length scale, and stratification expressions for both air and sea boundary layers. The effects of the temperature inversion and the density jump are incorporated into the equations of turbulent kinetic energy of the atmosphere and ocean by a parameterization. A series of numerical experiments was conducted to determine the effects of various strengths of the inversion layer and surface heat fluxes in the atmosphere and of the density-jump layer in the ocean on the structure of the interacting boundary layers.The numerical results show that the temperature inversion in the atmosphere and density jump in the ocean have strong influences on turbulent structure [especially on the turbulent exchange coefficient (TEC) and turbulent kinetic energy (TKE)] and on air-sea interaction characteristics. Maxima of TKE and TEC strongly decrease with increasing strength of the inversion layer, and they disappear for strong inversions in the atmosphere. Certain strengths (density differences between the upper and the lower layers) of the density-jump layer in the ocean (2 0.1 g/cm3) produce double maxima in TEC-profiles and TKE-profiles in the ocean. The magnitudes of air-sea interaction characteristics such as geostrophic drag coefficient, and surface drift current increase with increasing strength of the density-jump layer in the ocean. The density-jump layer plays the role of a barrier that limits vertical mixing in the ocean. The numerical results agree well with available observed data and accepted quantitive understanding of the influences of a temperature inversion layer and a density-jump layer on the interacting atmospheric and oceanic boundary layers. 相似文献
15.
A cloud-ocean planetary boundary layer (OPBL) feedback mechanism is presented and tested in this paper. Water vapor, evaporated from the ocean surface or transported by the large-scale air flow, often forms convective clouds under a conditionally unstable lapse rate. The variable cloud cover and rainfall may have positive and negative feedback with the ocean mixed layer temperature and salinity structure. The coupling of the simplified Kuo’s (1965) cumulus cloud model to the Kraus-Turner’s (1967) ocean mixed layer model shows the existence of this feedback mechanism. The theory also predicts the generation of low frequency oscillation in the atmosphere and oceans. 相似文献
16.
Edward H. Barker 《Boundary-Layer Meteorology》1977,11(3):267-294
A two-dimensional boundary-layer model is described. The model is designed to predict and study the effects of meteorological changes on the formation and dissipation of fog and stratus. Radiational heat loss along with the transport of static energy, moisture and momentum are treated. Cloud droplet distributions are parameterized using a gamma distribution from which radiative properties and droplet fall velocities are computed. Turbulent exchange coefficients are calculated using the Monin-Obukhov theory of similitude which accounts for variations in atmospheric stability. Although the boundary-layer depth depends only on turbulent intensity during stable atmospheric conditions, its growth during unstable conditions is determined from the capping inversion's intensity and the amount of turbulence generated at the surface.Several experiments are presented which demonstrate the effects of various meteorological parameters on the formation and duration of stratus and fog. Energy-budget analyses show the importance of each of the physical processes being modeled.Although not new, radiative transfer processes are shown to be extremely important in the transfer of heat from the boundary layer and in the process of fog formation. Fog formation location is highly sensitive to the moisture content upstream, whereas changes in wind speed had much less effect in the variance of fog location.Numerical experiments with other processes such as back radiation from the atmosphere, haze and cloud droplet population, are described and shown to have smaller effects. 相似文献
17.
E. S. Sarachik 《Dynamics of Atmospheres and Oceans》1978,2(5):455-469
Because the atmosphere and ocean are interacting systems, it is inappropriate to specify sea surface temperature when dealing with the atmosphere, or atmospheric anemometer level temperature and moisture when dealing with the ocean. All of these quantities should be determined interactively in terms of the external forcing: the solar constant.In the tropics, it is shown that the (cumulus) convective processes may be described by a one-dimensional cloud model. The near-surface ocean may similarly be described by a one-dimensional mixed-layer model. The coupling is achieved through a sea surface flux budget combined with the flux parameterizations implied by Monin-Obukhov similarity theory.The coupled one-dimensional atmosphere-ocean model is applied to the equilibrium situation in which all temperatures reach a steady state. Since the ocean, lacking an internal heating or cooling mechanism, can only be heated or cooled through sensibleheat fluxes through the sea surface, in equilibrium these fluxes must vanish. The atmosphere, however, maintains a stable lapse rate by balancing cumulonimbus heating against net radiative cooling. All water precipitated from cumulonimbus clouds must have evaporated from sea surface. It is shown that this equilibrium system is closed and determinable solely in terms of the solar constant.For various values of the solar constant, the sea surface temperature, the flux of latent and sensible heat from the surface, the height of the tropopause, mixed layer, and trade inversion layer, and generally, the entire vertical structure of the tropical atmosphere and near-surface ocean can be determined. The equilibrium sea surface temperature is shown to be relatively insensitive to changes in the solar constant, additional solar flux being compensated mainly by additional evaporation. Finally, the usefulness and limitations of the model are pointed out. 相似文献
18.
Single-point, three-component turbulent velocity time series data obtained in the atmospheric boundary layer over the ocean reveal coherent structures that are consistent with a model of a steady linearly varying spatial velocity field that translates past the measurement point at constant velocity. The kinematic model includes both strain and rotation rates and has implications regarding vortex generation, vortex pairing, vortex break-up, and stability. While the complete specification of the dimensions, spatial velocity gradients, and translational velocity of the linear coherent structure (LCS) cannot be made from the single-point, three-component measurements, the model LCS velocity time series can be determined from least- squares fits to the data. The total turbulent kinetic energy is used to find in the record the initial and final times of a model LCS in the data, i.e., the time interval over which a model LCS is passing over the anemometer. Maxima in the kinetic energy removed from the data (by subtraction of the model LCS velocity functions from the data) are used to identify the most-energetic model LCSs. These model LCS velocity functions replicate the essential large-scale features of the time series of the three-component velocity fluctuations, most noticeably in the streamwise component. The model LCS decomposition was used to perform a scale analysis of the data, which was compared to the usual Fourier method. Time intervals of model LCSs were found successively in the data, after subtracting the previous fits. This process resulted in a series of 'levels with a number of LCSs found at each level. About six levels account for most of the kinetic energy. The model also allows the computation of the Reynolds stress components, for which six levels also are sufficient. The recomposition of the time series on a LCS-by-LCS basis compares well with the mode-by-mode Fourier recomposition for the average momentum fluxes and kinetic energy. 相似文献
19.
三维辐射传输模式分析非均匀云对天空辐射场影响 总被引：4，自引：1，他引：3
为了解非均匀分立云体分布状况下的天空辐射场与无云晴空辐射场的差异, 本文借助一个三维辐射传输数值模式SHDOM模拟了离散云块分布条件下的天空辐射场分布, 重点分析不同云况分布情况下“非云”大气的辐射分布特征, 并将该区域与无云晴空大气辐射场的相同区域进行了比对。工作主要从辐亮度以及450 nm/650 nm的辐射比两参数入手进行讨论。研究发现, 相对无云晴空大气, 云的存在会对周围“非云”大气散射辐射产生影响, 影响程度与云量、云及气溶胶光学厚度等参数相关。数值模拟结果表明, 在云量不太大的条件下, 无云视场空间的大部分辐射值与无云晴空相比变化很小, 集中在±2％之间。这一结果表明, 已有的一维均匀大气辐射传输模式运算结果所得云与非云相元的判据基本适用于非均匀分布的有云大气。另一方面, 模拟结果表明我们也完全可以利用非均匀有云大气中的无云视场观测结果进行大气气溶胶等晴空大气光学特征的探测研究。 相似文献
20.
热带大气垂直环流对海表温度异常的响应——一个初步的理论分析 总被引：1，自引：0，他引：1
本文提出了一个β平面定常的线性二维模式,并考虑了海面边界层和赤道侧向边界层,讨论了热带海表温度异常对大气所产生的垂直环流——经向环流和纬向环流。结果表明:热带大洋东部(例如太平洋)海表温度比平均状态暖而西部较冷时,其上空经向环流(Hadley环流)比平均状态强,而纬向环流(如在太平洋上,称Walker环流)弱。相反,当热带大洋西部暖而东部冷时,经向环流减弱,纬向环流加强。这些是与观测事实比较一致的。 相似文献