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对临海沙漠地区非均匀地表区域地表能量通量和蒸发(蒸散)的研究,是一个十分重要但又是一个难点问题。本文提出了1个基于卫星遥感和地面观测的参数化方案,并把其应用于沙特阿拉伯吉达地区,利用1个景的陆地资源卫星Landsat-7E^TM^ 资料进行了分析研究,得到了一些有关临海沙漠地区非均匀地表区域地表特征参数、植被参数和地表能量通量的新概念。最后讨论了所提出的参数化方案的适用范围和需改进之处。 相似文献
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卫星遥感藏北高原非均匀陆表地表特征参数和植被参数 总被引：20，自引：0，他引：20
卫星遥感在研究青藏高原北部地区(藏北高原地区)非均匀陆表地表特征参数和植被参数时有其独到的作用.作者提出了基于NOAA-14 AVHRR资料推算藏北高原地区地表特征参数和植被参数的方案,并把其用于全球能量水循环之亚洲季风青藏高原试验(GAME/Tibet)试验区.同时利用3个景的NOAA-14 AVHRR资料进行了分析研究,得到了一些有关藏北地区非均匀地表的区域地表特征参数(地表反射率、地表温度)和植被参数(INDV、植被覆盖度和叶面指数ILA). 相似文献
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利用武威地区2008年5月30目的Landsat ETM＋第六波段数据。经过大气和比辐射率校正后,运用单窗算法反演武威地区地表温度,得出该地区夏季地面温度场的分布规律。结果表明,冰川表面温度最低,针叶林及绿洲次之,沙漠最高,地表温度以绿洲为中心从里到外呈带状分布。并运用归一化植被指数（NDVI）计算该地区植被覆盖度（Fg）,进一步研究植被盖度及归一化植被指数与地表温度的相互关系,结果表明几种典型地物随NDVI值的减小,温度呈递增关系,植被盖度与地袁温度成线性负相关。 相似文献
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HEIFE非均匀陆面上区域能量平衡研究 总被引：8，自引：1，他引：7
卫星遥感在研究非均匀陆面上地－气间能量和水循环过程时有其独到的作用。本文介绍了一种利用陆地资源卫星ＴＭ资料进行非均匀陆面上区域能量平衡研究的参数化方案。以两个景的ＴＭ资料（１９９１年７月９日,夏季;１９９１年１０月２９日,近冬季）为个例,结合“黑河实验”（ＨＥＩＦＥ）期间的地面观测资料分析研究了实验区非均匀陆面上地表特征参数（地表反射率、标准化差值植被指数和地表温度）及能量平衡各分量（地表净辐射通量、土壤热通量、感热和潜热通量）的区域分布及季节差异,同时将所得的结果与地面观测的“真值”作了比较。结果表明：（１）由于黑河实验区下垫面状况十分复杂,戈壁、沙漠与绿洲交错分布,故在整个实验区内各地表特征参数及能量平衡各分量的分布范围亦比较宽;（２）地表特征参数及能量平衡各分量在实验区的绿洲、戈壁及沙漠上各有其特定的代表值;（３）地表能量平衡各分量的区域平均值在整个实验区内基本平衡;（４）夏季与近冬季的地表特征参数及能量平衡各分量的分布特征存在着显著差异。所得的这些结果与地面观测的“真值”和局地研究的结论基本一致。这些分析对非均匀下垫面中尺度模式陆面过程参数化方案的建立以及模式预报效果的检验都具有不可缺少的重要意义。 相似文献
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黑河实验区非均匀地表能量通量的数值模拟 总被引：12，自引：13，他引：12
利用三维非静力RAMS模拟研究了黑河实验区非均匀地表能量通量，模拟结果表明：绿洲地表净辐射通量较沙漠戈壁大；绿洲及沙漠戈壁下垫面上的Bowen比分别为0．4和4．0；夜间绿洲上整晚维持蒸发，并有负感热通量。模拟结果与测站实测结果与卫星反演值的对比研究指出，RAMS对绿洲下垫面潜热通量的模拟和沙漠戈壁下垫面感热通量的模拟与实测值基本一致。卫星遥感反演及数值模拟方法对净辐射的估算与实测较吻合，绿洲地表感热通量的卫星反演值较数值模拟结果更接近于实际，但潜热通量的模拟值则较卫星估算值更接近于实际；沙漠戈壁地表则是感热通量的模拟值较卫星反演值更接近于实际。上述分析为今后结合卫星遥感改进RAMS陆面过程参数化，使使用于模拟研究干旱区非均匀下垫面地气相互作用提供了可靠依据。 相似文献
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全球及中国区域长时间序列卫星数据集(CG-LTDR)包括地表反照率、叶面积指数、土地覆盖分类、植被指数和积雪覆盖产品。为了应用CG-LTDR和其他卫星气候数据,基于WEBGIS技术建立了CG-LTDR系统,实现对卫星气候数据集的在线管理和显示分析功能。本文介绍了CG-LTDR卫星气候数据集及显示分析系统,并利用NDVI数据对中亚及周边核心区的植被状况和长期变化进行分析。结果表明:哈萨克斯坦、吉尔吉斯斯坦和塔吉克斯坦地区及新疆西部和北部植被平均状况较好。中亚地区的植被在20世纪90年代和2000年代整体状况较好,20世纪80年代相对较差,2010年后空间变化不均。特别是从21世纪开始我国西部沙漠化程度加重,一些地区地表植被严重破坏,生态环境变化不容乐观。由于中亚地区常规观测少,利用CG-LTDR卫星气候数据集对中亚地区进行应用具有很好的意义,CG-LTDR可以为农牧资源和生态环境提供有效信息。 相似文献
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H.B. Kruger 《大气与海洋》2013,51(2):61-65
A wide set of size‐distribution models of haze and fog droplets expressed in terms of the modified gamma distribution function have been used for evaluating the proportionality coefficient b in the empirical relationship between visibility V and liquid water content LWC, that is V=b (LWC)‐ 2/3, as proposed by Eldridge (1966). The evaluations of b turn out to be consistent with the values proposed in the literature and give evidence for its close dependence on the shape‐parameters of the droplet size distribution, especially as regards the mode radius and the width of the larger‐droplet wing. Three average relationship curves are proposed respectively for dense haze, “dry and cold” fog and “wet and warm” fog. Corresponding to these cases, three correlation lines are presented between b and the ratio of the volume extinction coefficient at 3.70 μm wavelength to that at 0.55 μm, evaluated for the same uniform path in hazy and foggy atmospheres. Applied to measurements of infrared and visible transmission such correlation lines give the possibility of estimating the most proper value of b to be used in Eldridge's relationship for different atmospheric conditions. 相似文献
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During the 1974 growing season, a micrometeorological measurement program was conducted at Simcoe, Ontario, Canada to study atmospheric and surface control on hourly and daytime evaporation from soybeans. For days when leaf area index exceeded unity, daytime evaporation varied linearly with volumetric soil moisture content when the latter was less than 0.12. At larger volumetric soil moisture contents, evaporation proceeded at a potential rate. The data confirm the usefulness of the Priestley and Taylor model with a proportionality constant of 1.26. 相似文献
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Information from a variety of sources, including an airborne field expedition in November 1985, is used to produce estimates of the annual emissions of some hydrocarbons from bushfires, and isoprene from trees, in tropical Australia. For the continent north of 23° S the annual bushfires (biomass burning) input was estimated, in units of Tg carbon, to be 2 TgC (uncertainty range 0.8–5 TgC), emitted predominantly during the May to October dryseason. Isoprene emissions during this period were estimated also to be 2 TgC (uncertainty range 0.5–8 TgC), but were estimated to be an order of magnitude higher during the November to April wet season, at a level of 23 TgC (uncertainty range 6–100 TgC).The large annual emission of isoprene over the tropical part of the Australian continent yields ppbv levels of isoprene measured at the surface in summertime. Isoprene reactivity with hydroxyl radical is such that at these concentrations isoprene must be a dominant factor in controlling the concentration of OH radical in the convective boundary layer. Simple arguments based on the convective velocity scale suggest that the shape of the isoprene vertical profile in November 1985 would be consistent with available data on the OH-isoprene reaction rate if OH concentration in the boundary layer averaged about 2.5×106 cm-3 over the middle part of the day.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden. 相似文献
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Annual methane emission from Finnish mires estimated from eddy covariance campaign measurements 总被引：4，自引：0，他引：4
K. J. Hargreaves D. Fowler C. E. R. Pitcairn M. Aurela 《Theoretical and Applied Climatology》2001,70(1-4):203-213
Summary Measurements of landscape-scale methane emission were made over an aapa mire near Kaamanen in Finnish Lapland (69° 8′ N,
27° 16′ E, 155 m ASL). Emissions were measured during the spring thaw, in summer and in autumn. No effect of water table position
on CH4 emission was found as the water table remained at or above the surface of the peat. Methane emission fluxes increased with
surface temperature from which an activation energy of −99 kJ mol−1 was obtained. Annual emission from the site, modelled from temperature regression and short-term flux measurements made in
three separate years, was calculated to be 5.5 ± 0.4 g CH4 m−2 y−1 of which 0.6 ± 0.1 g CH4 m−2 y−1 (11%) was released during the spring thaw which lasted 20 to 30 days.
The effect of global warming on the CH4 budget of the site was estimated using the central scenario of the SILMU (Finnish Research Programme on Climate Change) model
which predicts annual mean temperature increases of 1.2, 2.4 and 4.4 °C in 2020, 2050 and 2100, respectively. Maximum enhancements
in CH4 emission due to warming were calculated to be 18, 40 and 84% for 2020, 2050 and 2100, respectively. Actual increases may
be smaller because prediction of changes in water table are highly uncertain.
Received September 17, 1999 Revised October 16, 2000 相似文献
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Prior research shows that public opinion on climate politics sorts along partisan lines. However, they leave open the question of whether climate politics and other politically salient issues exhibit tendencies for issue alignment, which the political polarization literature identifies as among the most deleterious aspects of polarization. Using a network approach and social media data from the Twitter platform, we study polarization of public opinion toward climate politics and ten other politically salient topics during the 2019 Finnish elections as the emergence of opposing groups in a public forum. We find that while climate politics is not particularly polarized compared to the other topics, it is subject to partisan sorting and issue alignment within the universalist-communitarian dimension of European politics that arose following the growth of right-wing populism. Notably, climate politics is consistently aligned with the immigration issue, and temporal trends indicate that this phenomenon will likely persist. 相似文献
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The first 1,000 year long Carpathian tree-ring width chronology was established based on living and subfossil stone pine (Pinus cembra L.) samples from an upper timberline forest located in Calimani Mts. (Romania). Tree-ring data were standardized using the regional curve standardization method in order to preserve the low and medium frequency climate signals. The de-trended index strongly correlates with summer mean temperature both at annual and decadal scales. The Calimani summer mean temperature anomalies were reconstructed for the period ad 1163-2005 applying the rescaling method. This new climate proxy from the Carpathians shows similar fluctuations to other North Hemispheric temperature reconstructions, but with periods of distinct differences. The fingerprint of Little Ice Age in the Calimani area is visible between ad 1370 and 1630 followed by lagged cold decades in ad 1820 and 1840. The recent warming is evident only after the 1980s in our reconstruction. 相似文献
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张人禾 《中国气象科学研究院年报》2001,(1)
刚刚走过的2001年,是新世纪的开局之年,也是我们祖国大事连连、喜事频频的一年,北京的申办奥运成功、中国的成功入世、中国足球的如愿出线、APEC会议的成功举办……,在给全国人民带来无比喜悦的同时,也给正处于科技体制改革的中国气象科 相似文献
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在物理学研究中,尺度特征是一个必须要处理好的问题,大气科学也不例外,在不同的时空尺度条件下,运动所遵循的规律会表现出很大差异,或者说运动的特征会因尺度的变化而完全不同。在以往的多尺度研究领域,尺度分离问题相对比较成熟,可通过有效的方法、技术来实现。相对而言,对不同尺度系统间的相互作用,尽管也从不同角度开展过大量工作,但仍显薄弱。如果不能清晰、合理地分析尺度间相互作用问题,就难以解释大气运动如何在较为平稳的状态下产生变异,并有新尺度系统产生。多尺度相互作用一般用尺度间的能量传输来衡量,但这种传输属流体的内部过程,要靠动力学理论来推断。然而流体力学中较长时间延用的能量传输经验公式有着重大缺陷——能量不守恒,导致我们用此所作的动力学诊断不能如实反映大气内部的物理过程。针对这个问题,过去20年来气象学家从最基本的物理概念出发,通过构造物理意义上自洽的数学工具,在严格意义上导出了流体内部多尺度之间的能量传输公式。 相似文献