共查询到19条相似文献,搜索用时 62 毫秒
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对大气环流模式提出了完全控制试验的概念,对包括陆面下垫面在内的整个地球表面的热力强迫作了控制,在FC中,可以更好地分离出大气内动力过程对于模式大气短期气候异常的影响。 相似文献
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大气谱模式中质量守恒格式的研究 总被引:2,自引:2,他引:2
当前在世界上广泛采用的谱模式,是以地面气压ps取对数作为展谱变量,模式大气总质量不守恒。本文研究这样的问题,提出了以热力学变量比容α代替温度变量T的方法,并以地面气压ps本身作为展谱变量,这样可以保持大气总质量守恒。同时,由于以α作展谱变量,可使重要项气压梯度项为二阶变量组成,截谱后,不会出现混淆误差。计算结果表明,这样改变后,大气总质量保持守恒。同时消除了混淆误差的出现。 相似文献
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青藏高原模式大气(暂用) 总被引:2,自引:0,他引:2
本文根据青藏高原地区高空温、压、湿的气候资料并参考中纬度与热带模式大气初步建立了青藏高原不同季节的模式大气,以供该地区辐射传输研究的需要。 相似文献
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大气边界层数值模式的发展 总被引:1,自引:0,他引:1
本文简要介绍了目前较为常用的一些边界层数值模式及其发展概况,同时也介绍了一些常用的模拟方法及各自的优缺点,最后简述了边界层数据模拟的发展趋势。 相似文献
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模式大气中的年代际变化 总被引:3,自引:1,他引:3
用1945~1993年COADS SST强迫AGCM进行了连续49年的模拟积分,分析了模式大气中的年代际变化,并和NCEP再分析资料进行了比较。结果表明,模式大气中,无论是热带太平洋风场,还是中、高纬大气环流均存在显著的年代际变化;AGCM基本上能较好地模拟热带太平洋和中、中纬大气环流年代际信号的是分布和时间变化趋势;从时间变化上盾,热带太平洋风场的模拟结果要好于中、高纬大气,说明SST仍然是膨响 相似文献
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本文描述了基于PIC方法的三维大气扩散粒子分裂(ADPS)模式,并用解析解和1988年的广州地区现场观测资料验证了本模式.模式根据局地均匀和定常假设引入大粒子概念、烟团扩散原理和大粒子分裂技术,并运用了嵌套网格.ADPS模式用于模拟气态污染物在大气中的散布,同时也具备模拟TSP扩散的效能. 相似文献
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I.INTRODUCTIONSincethe1980s,ithasbenfoundthatsomeatmosphericdispersionmodelsforconventionalapplicationsarenotgoodincoinciding... 相似文献
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Plume meandering and averaging time effects were measured directly using a high spatial resolution, high frequency, linescan
laser-induced fluorescence (LIF) technique for measuring scalar concentrations in a plume dispersing in a water channel. Post-processing
of the collected data removed time dependent background dye levels and corrected for attenuation across the laser beam to
produce accurate measurements over long sample times in both a rough surface boundary-layer shear flow and shear free grid-generated
turbulent flow. The data were used to verify the applicability of a meandering plume model for predicting the properties of
mean and fluctuating concentrations. The centroid position of the crosswind concentration profile was found to have a Gaussian
probability density function and the instantaneous plume spread about the centroid fluctuated log-normally. A modified travel-time
power law model for averaging time adjustment was developed and compared to the widely used, but much less accurate, 0.2 power-law
model. 相似文献
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StudyontheThermalinternalBoundaryLayerandDispersionofAirPollutantinCoastalAreabyNumericalSimulation¥JiangWeimei(蒋维楣)andYuHong... 相似文献
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源项对FLEXPART模式模拟福岛核事故放射性物质长距离传输的影响 总被引:1,自引:0,他引:1
对包括拉格朗日粒子模式在内的大气扩散模式,提供准确的源项有助于获取更好的模拟结果。以日本福岛核电站2011年3月发生的核泄漏事故为研究对象,采用日本原子能机构Terada源项以及挪威大气研究所Stohl源项,利用FLEXPART(FLEXible PARTicle dispersion mode)模拟了放射性物质137Cs在全球大气中扩散传输的过程,并利用大气辐射监测数据讨论了基于两种源项模拟烟云的时空分布特征,探讨了源项对模拟结果的不确定性影响。结果显示:Terada源项及Stohl源项之间释放总量、释放速率、释放高度等虽然略有差别,但总体趋势描述相似,使得基于两源项的模拟烟云的扩散过程及影响区域基本一致。两模拟烟云在中纬度西风带作用下,均表现为自西向东扩散,经过太平洋、美洲大陆、欧洲,最后在整个北半球传输。基于两源项在亚洲—太平洋及北美大陆等近距离的模拟烟云的首次到达时间与首次监测时间吻合度较好,在全球尺度上基于Stohl源项的模拟在首次到达时间方面表现更优。其次,基于两源项进行全球尺度的模拟,近距离站点的模拟效果优于远距离站点模拟效果,且基于Stohl源项的模拟精度较好,Terada源项可能存在低估。另外模式进行全球尺度的模拟时,针对不同粒子数目对模拟结果的影响进行了分析,发现粒子数目的多寡对模拟精度有所影响,也影响模拟烟云扩散后期的疏密程度。 相似文献
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中高纬度大气低频模态研究进展 总被引:1,自引:0,他引:1
大气低频模态是导致中高纬地区季节及气候变化的主要因素,加强低频模态动力机制的认识对于提高短期气候预测水平具有十分重要的科研意义和应用价值。由于中高纬大气低频环流本身的复杂性,关于其动力机制的研究仍然是大气动力学中重点难点问题。本文简单回顾了激发维持低频模态的前两种机制,即:外源强迫、气流的纬向非均匀性对大气低频模态的影响。从观测事实和模式结果出发,着重介绍了瞬变波与基本气流相互作用激发维持低频模态的第三种机制,且详细阐述了线性假设条件下,瞬变波与基本气流相互作用的动力机制。本文最后针对瞬变波与基本气流相互作用研究中一些尚未解决的问题进行了讨论。 相似文献
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We show that a forward Lagrangian stochastic (LS) model simulates well the ensemble-averaged concentration transient due to
a short time (5 min) point source in the uniform atmospheric surface layer. In LS models, computational particles, which may
not descend below ground level, are necessarily reflected at an imposed (artificial) boundary above ground. Model results
were rather insensitive to the placing of the lower reflection boundary, and no definite benefit stemmed from including a
parametrization for unresolved delays/displacements beneath the lower boundary. 相似文献
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Atmospheric deposition can provide a significant fraction of the nitrogen loading to coastal waters. The Delmarva Peninsula,
on the eastern shore of the Chesapeake Bay, is a region with intense poultry production that may supply a significant source
of atmospheric ammonia (NH3). There is a need to quantify ammonia NH3 from representative growing methods in this region in order to more accurately estimate agricultural NH3 emissions and to develop best management practices. In this study, NH3 emissions were determined at an 18,600-bird tunnel-ventilated chicken house using a modified sampling grid (a planar arrangement
normal to the length of the house) with Ogawa passive samplers to characterize the emission plume downwind from the house.
This improvement in the sampling strategy, compared to a previous study, simplified the inverse Gaussian plume analysis which
improved the confidence in the emission factors. In this study, a total of four separate plume characterizations were conducted
over the final 3 weeks of the 6-week broiler grow-out cycle. The mean emission factor observed at the tunnel-ventilated house,
0.13 g NH3–N/bird-day, was an order of magnitude lower than that previously observed at a nearby side-wall ventilated house. Although
not all growing variables were measured, the large difference in emission factors between the two ventilation regimes suggest
that modern, tunnel-ventilated houses may result in a significant decrease in NH3 emissions compared with traditional growing methods. This variability in emission factors underscores the need for characterizing
chicken houses under various conditions and determining the factors that control these atmospheric emissions. 相似文献
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利用GPS探空仪实测数据计算大气折射率的高度廓线,建立大气折射误差模型。并分析大气折射效应对方向交汇、到达时间差以及综合法3种甚高频闪电定位方法测量精度的影响。结果表明,对于定位距离,大气折射对方向交汇法的影响最大,误差最大值可达到116.52m,平均误差为30.18m;大气折射对时间差法的影响最小,误差最大值约为44.70m,平均值为12.32m;对综合法的影响介于二者之间,误差最大值约为58.90m,平均值为16.74m。在综合法中,选取离闪电源较远测站进行方向交汇的定位误差是选取较近站点的定位误差的1.6倍,因此应当选取近站点。考虑到GPS授时误差,要保证大气折射对闪电定位造成定位误差小于GPS时间同步带来的误差,3种闪电定位方法的站间距应分别不大于28km、60km、45km。 相似文献