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1.
水面蒸发量的一种气候学计算方法 总被引：15，自引：1，他引：15
用北京日射站和官厅蒸发站的辐射和蒸发资料对彭曼公式进行订正,得出修正公式 E_0=(ΔH_0+γE_α)/(Δ+γ) H_0=1/59[0.95Q_A(0.167+0.583n/N)-σT_a~4(0.32-0.26e_a~(1/2))(0.30+0.70n/N)] E_a=0.13(e_a-e_d)(1+0.77u),其中H_0是表示为蒸发量单位的辐射平衡,E_a是由风速和饱和差决定的“干燥力”。 自由水面的蒸发量E可用下式表示 E=E_0-F/L,其中F是水面向下的热通量,在升温季节为正值,在降温季节为负值。由于缺少水温梯度观测资料,F不能直接计算。本文建议,对升温或降温季节分别建立水面蒸发E倚蒸发势E_0的回归方程。得出北京地区各月蒸发量的计算公式如下 0.963 E_0-7.0 4—7月 E=0.902 E_0+26.0 9—10月 E_0 8月 相似文献
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最大蒸发量的计算、分析及其应用 总被引：3，自引：0，他引：3
本文利用潘曼(Penman)公式E_0=(ΔH rE_a)/(Δ r),计算了宁夏各地自然蒸发量E_r值,分析了E_r的时空分布特征;以E_r/r的比值(干燥指数)作为划分宁夏农业气候区域的指标,并根据E_r=L_iE_0的关系式,订正了宁夏地区春、夏、秋各季的转换系数K_i值;以计算出的农作物各生育期内自由水面蒸发量E_0值和实测田间蒸发量′fc的比例系数(′fc/E_0),作为土壤-植物-近地表层这个系统的水份状况的重要指标,鉴定出了宁夏灌区小麦、水稻、小糜子等主要作物生育期的蒸发系数j_t值和耗水量。用水分平衡方程式,求出了作物灌溉量和生育末期土壤水分储水量,为研究宁夏农业气候区划及建立农作物水分平衡预报,提供了依据。 相似文献
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越赤道气流与中国天气关系的初步统计分析 总被引：14，自引：0，他引：14
本文利用1974—1979年的资料,分析了夏季风期间(6—9月)东半球对流层低层(850hPa)及高空(200hPa)越赤道气流的主要特征。定义了东半球越赤道气流总量E以及0°—90°E、90°E—180°越赤道气流总量E_1、E_2,分别统计了它们与中国大陆降水、西北太平洋台风发生数以及北半球副热带高压活动的关系。 相似文献
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1931年桑斯维特建立了一种气候区划方法,即采用有效雨量(降水与蒸发之比值)的分布来进行分类。1948年他又根据在美国中西部和墨西哥等地进行灌溉试验时所得的数据(1936—1945年)提出可能蒸散(potential evapotranspiration,用PE表示)这一指标作为气候分类依据,并修订了他原来的气候区划方法。在表达大气湿润状况时用的是有效雨量湿润指数(moisture index)。同时为了便于计算,桑斯维特和马瑟(J.R.Mather)于1957年制作了一系列表格从而简化了烦杂的计算,该方法在南、北美洲应用较广,具体介绍如下: 一、年中某一时期的降水(P)如超过实际蒸散量(AE),则有多余水份(S),即S=P-AE时为湿润气候,其湿润指标(humidity index)为I_h=100S/PE,即剩余水份占可能蒸散的百分率。 相似文献
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在本文中作者制作了我国东半部水量平衡三要素的分布图,并进行了扼要的分析和讨论。各地的多年平均降水量(r)是根据实际观测的数据。多年平均自然蒸发量(z)的数值是根据下列布德科公式计算得来的(参考文献[6]):z=[R_0r/LthrL/R_0(1-chR_0/rL+shR_0/Lr)]~(1/2),式中 th,ch,sh 各代表双曲线正切、余弦及正弦;而 R_0/L=z_0是代表水源不缺条件下湿润地面的最大可能蒸发量,其数值根据作者前文(文献[1])计算的结果。多年平均迳流量(f)则根据水量平衡方程 f=r-z 间接求得。除了计算年蒸发量的分布以外,本文还计算出各季蒸发量的数值,但其精确度自然不及年量的计算。在本文中,还按17个不同流域进行水量平衡的计算和讨论,并绘成多年平均年迳流系数分布图一幅,其结果可与文献[9]相比较。 相似文献
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利用文献[4]得到的推广的β平面近似式为f=f0+β0 y—（δ0/2）y2,研究由δ0项所引起的一类Rossby孤立波，而不考虑基流切变和地形等因子的作用。经过计算可以发现，当经向波数为1时，这种孤立波具有显著的南低北高的偶极子阻塞结构，它主要存在于弱西风气流中，并且偶极子的能量随着纬度的增高更容易集中(即高纬偶极子结构趋于局地化)，因而，β随纬度的变化可能是中高纬度地区偶极子阻塞产生的原因之一。 相似文献
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台风螺旋雨带——涡旋Rossby波 总被引：35，自引：6，他引：35
台风中的螺旋云雨带是由多种探测手段被观测到的现象 ,是为大家所共识的不争事实。但是 ,对它的形成、维持的理论解释 ,虽有多种学说 ,一直以来人们都倾向于重力惯性波说。而重力惯性波说有一个致命的弱点 ,即波的相速理论值为 10 1m/s量级 ,它要比螺旋云雨带实测移速只有 10 0 m/s几乎大一个量级。于是从前几年开始 ,人们又回到 30多年前提出的涡旋 Rossby波说那里去寻找合适的解释。经典的Rossby波是 β =(df/dy)作用的大尺度波动 ,而适用于台风中螺旋云雨带的涡旋———Rossby波乃是 f平面 (β =0 )上的中尺度波动。那末 ,对这两类尺度不同和成波机理不同的波动 ,何以均冠予Rossby波一词 ?本文试图从动力学等价原理上 ,对此作统一联系的说明。其结果是 :台风基本气流的涡度 ζ随径向 (r)变化的梯度d ζdr=1rr(r vλ) ,在动力学上等价于科氏参数 f随纬度变化的梯度即β=df/dy ;或者说它们在绝对涡度守恒的前提下 ,作为波扰动的成波机理是等价的 相似文献
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要合理利用水资源,必须了解水份循环实况,也就要进行水份平衡的计算,蒸发项的计算是必不可少的。在目前的技术条件下,直接而且准确地测量自然蒸发是不易做到的。一般采取两类方法:即蒸发力的测量和估算以及蒸发器直接测量法。我国目前大多数气象台站用20厘米口径的小型蒸发器来测量水面的蒸发,所积累的资料年代也较长。但小型蒸发器水体面积小,口沿又离地70厘米高。显而易见,所测出的蒸发量代表性稳定性较差,使用效果也并不理想。E—601型蒸发器就相对地克服了许多小型蒸发器的缺陷。有一定代表性和稳定性。但E—601型蒸发由于观测所得的资料年代短,很难适应各方面需求。如何能较好地找出小型与E—601型蒸发量之间的关系,通过订正使已有的小型蒸发资料发挥更大效益呢?本文就此作一些探讨。 相似文献
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1 引言彭曼(Penman,1948)建立的蒸发方程,起初用来估计开敞水面的蒸发。该方程可表示为: E_0=[(△R_n) (γE_a)]/(△ γ) (1)式中E_0为开敞水面的蒸发(mm d~(-1));R_n为净辐射(mm/天)。若不直接观测净辐射,则可用下式估计: 相似文献
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我局从1999～2003年,测报工作连续4年未出现错情,在此期间共有1个250个班,9个百班无错通过上级业务部门验收.在仪器保管、使用、维护上符合要求,对外报送的各种表、簿都能做好出门合格. 相似文献
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Summary ?Some features of the climate system that can be considered predictors of the onset and end of the convective season over
the Amazon were identified using one-month lag correlations and field composites. The fields analyzed were sea surface temperature
(SST), outgoing long-wave radiation (OLR), vertical velocity and upper tropospheric winds.
Warm (cold) anomalies in the SST in the tropical North Atlantic and the Caribbean Sea tend to be associated with delayed (early)
onsets. Likewise, there is a tendency towards a delayed (early) end of the convective season with cold (warm) anomalies in
these ocean regions. In addition, the SST in the cold tongue region of the equatorial Pacific is negatively, though weakly
correlated with the onset date. The signal of this SST is more evident in the case of the end date, which is earlier with
respect to its mean date in most of El Ni?o cases.
The convective activity intensity itself conditions the onset and the end of the convective season, as it is evidenced by
the behavior of the OLR and the vertical velocity fields. The more (less) intense the convective activity over South America
during the preceding month, the earlier the onset and the later the end of the convective season on the Amazon region.
The prediction of the onset and end dates of the convective season in the Amazon region was explored using a simple multiple
regression technique based on the variables that have shown precursor signals with respect to these dates. The correlation
coefficient between the predicted and the observed onset date is 0.81, and in the case of the end date, it is 0.76. The skill
to predict early, delayed and normal categories was high, since in more than two thirds of the cases the category was successfully
predicted, and there were no predictions of categories opposed to those observed.
Received July 23, 2001; revised February 22, 2002; accepted April 26, 2002 相似文献
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Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale 总被引：1，自引：0，他引：1
G. Terence Meaden S. Kochev L. Kolendowicz A. Kosa-Kiss Izolda Marcinoniene Michalis Sioutas Heino Tooming John Tyrrell 《Atmospheric Research》2007,83(2-4):446-449
2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita's damage scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita's Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita's Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F′half = T / 2 = (B / 4) − 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F′double = T = (B / 2) − 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit scale has all the criteria needed for world-wide practical effectiveness. 相似文献
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准两年振荡对大气中微量气体分布的影响 总被引：11，自引：5，他引：6
NCAR的包含化学、辐射、动力相互作用的两维模式（SOCRATES）移植回国后进行了初步的模拟试验,用以研究某些对环境问题重要的微量气体的化学、辐射、动力传输过程。在不考虑极地平流层云和气溶胶表面非均相化学等情况下,模式积分多年,计算结果稳定,模拟的风场、温度场显示出正常的季节变化,模拟的微量气体分布与卫星实测资料对照,结果也比较一致。为了探讨热带平流层风场的准两年周期振荡（QBO）对平流层微量气体分布的影响,我们做了QBO强迫的数值试验,即在模式中加入QBO强迫,并与不考虑QBO强迫的模拟结果对比。结果表明,QBO与其相关的次级环流所引起动力输送的变化,使平流层微量气体分布发生变化。 相似文献
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Chunguang CUI Wen ZHOU Hao YANG Xiaokang WANG Yi DENG Xiaofang WANG Guirong XU Jingyu WANG 《大气科学进展》2023,40(4):711-724
Here, we analyze the characteristics and the formation mechanisms of low-level jets(LLJs) in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5) reanalysis dataset. Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs) concentrated at heights of 900–1200 m.The BLJs occur most frequently at 230... 相似文献
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The impact of high resolution modern vegetation cover on the West African climate is examined using the International Centre for Theoretical Physics Regional Climate Model implementing the NCAR Community Land Model. Two high resolution 25 km long-term simulations driven by the output from a coarser 50-km resolution simulation are performed for the period 1998–2010. One high resolution simulation uses an earlier and coarser-resolution version of plant functional type distribution and leaf area index, while the other uses a more recent, higher-quality, and finer-resolution version of the data. The results indicate that the new land cover distribution substantially alters the distribution of temperature with warming in Central Nigeria, northern Gulf of Guinea and part of the Sahel due to the replacement of C4 grass with corn; and cooling along the coastlines of the Gulf of Guinea and in Central Africa due to the replacement of C4 grass with tropical broadleaf evergreen trees. Changes in latent heat flux appear to be largely responsible for these temperature changes with a net decrease (increase) in regions of warming (cooling). The improved land cover distribution also results in a wetter monsoon season. The presence of corn tends to favor larger precipitation amounts via more intense events, while the presence of tropical broadleaf evergreen trees tends to favor the occurrence of both more intense and more frequent events. The wetter conditions appear to be sustained via (1) an enhanced soil moisture feedback; and (2) elevated moisture transport due to increased low-level convergence in regions south of 10N where the most substantial land cover differences are present. Overall the changes induced by the improved vegetation cover improve, to some extent, the performance of the high resolution regional climate model in simulating the main West African summer monsoon features. 相似文献
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流场配置及地形对西南低涡形成的动力作用 总被引：10，自引：8，他引：10
本文采用定常二层模式讨论较小地形及高、低层流场配置对西南低涡形成的动力作用。指出了西南低涡的形成是与盆地、河谷以及其上气流分层有关的一种定常态.在上、下为西风分层时期,低层的浅薄暖湿西风有利于西南低涡的形成.在上、下为东、西风分层时期,上层浅薄东风亦有利于西南低涡的形成.小型的凸起山脉对西南低涡的形成没有作用. 相似文献
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由中国历史气候记录对季风导致唐朝灭亡说的质疑 总被引：1，自引：0，他引：1
张德二 《气候变化研究进展》2008,4(2):126-130
2007年1月4日杂志发表了Yancheva等10人的题为"Influence of the intertropical convergence zone on the East-Asian monsoon"(热带辐合带对东亚季风的影响)的论文[1],这是德国波兹坦地学研究中心气候动力与沉积学科的主管豪格(G.H.Haug)率领的科研小组的一项成果,认为是季风的变化引起的长期干旱导致了唐朝的灭亡. 相似文献