共查询到20条相似文献，搜索用时 93 毫秒
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计算纯净液态水(平)面上不同温度的饱和水汽压公式有许多种,现就其中几种进行比较如下:1.史密森气象常用表(Smithsonian Meteorological Tables)所用的戈夫一格拉奇(Goff-Gratch)公式(1946): 相似文献
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一、引言干湿球温度表是用来取得大气中水汽含量的最通用的仪器之一。它是一个比较简单的仪器,只要对湿球维护得当,便可以得出很好的结果。它的缺点之一是对水汽压、露点和相对湿度的计算比较复杂,且难于用小型电子计算器或微信息处理机进行。本文提出了可用于这些计算的各种方程,并且说明了它们相对于戈夫-格拉奇(Goff-Gratch)公式的计算精度。应当注意下文涉及到在这些方程中所使用的符号:exp_(10)x≡10~x;“Ig”指以10为底的对数;“In”指以e 相似文献
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新疆地面有效辐射计算方法探讨 总被引：3，自引：0，他引：3
在对国内外计算地面有效辐射的经验公式进行评述的基础上，检验了各类经验公式在新疆的计算效果，从中找出了计算新疆地面有效辐射较可靠的经验公式。 相似文献
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关于太阳总辐射的气候学计算,已有许多人做了这方面的工作。在经验公式的时段划分问题上,有的是全年配制一个公式,有的是每季配一个公式,还有的是每月配制一个公式。而广东省太阳辐射候总量的气候学计算则是以自然季节来划分经验公式所取的时段的。萧文俊等人曾指出:经验公式的系数因气候条件的差异而发生变化。因此,按年或季来配制公式虽然方便,但是不能反映出各时段的气候特点,计算精度就会受到一定影响。按月配制公式,工作量会增加很多。在对我省太阳辐射月总量进行计算时,考虑到既要提高计算精度,又要尽可能减少工作量,我们用聚类分析法来解决经验公式的时段划分问题。 相似文献
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感热通量计算方法的研究是边界层研究中最重要的内容之一。基于中日JICA计划项目中青藏高原东缘四川盆地温江站的边界层铁塔观测资料初步研究了使用人工神经网络(ANN)计算边界层感热通量的方法,并将ANN和经验公式法计算得到的感热通量分别和真值作相关和误差分析。对2009年4月和5月的两个个例研究的结果表明:ANN计算结果和真值的相关性都高于经验公式法且趋势变化和真值更加吻合,ANN计算的2009年4月的感热通量与真值的均方根误差(RMSE)稍大于经验公式法,但2009年5月的RMSE明显小于经验公式法。 相似文献
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福建省散射辐射的计算方法及其分布特征 总被引：2，自引：0，他引：2
提出了综合考虑日照百分率和总云量来计算散射辐射的公式。将散射辐射Ｄ除以日照百分率Ｓ１，称其为净散射辐射。同时求出各月及年的净散射辐射与当地天文辐射的比值和总云量的相关系数ｒ。各月与年的相关系数均为正值，且ｒ均大于ｒ０．０１。在此基础上建立计算散射辐射的经验公式：Ｄ＝Ｓ１Ｑｏｅ＾ａ＋ｂＮ，式中Ｄ为散射辐射；Ｓ１为日照百分率；Ｑｏ为天文辐射；Ｎ为总云量；ａ和ｂ为经验系数。使用该经验公式求得福建省所有市 相似文献
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针对均匀水体假设的海水透明度经验计算公式不具有普适性的缺点,将海水在垂直方向上分为若干光学性质相近的均匀层,推导出非均匀水体中目标对比度传输方程,在此基础上,建立了海水透明度的计算模型。利用BROKE_WEST_ACS实测的海水固有光学性质数据和透明度盘观测数据,对计算模型进行了数值试验和效果分析。结果表明:模型计算值与透明度盘实测值平均相对误差为9.1%;该模型既克服了透明度盘测量易受天气状况和人眼差异影响较大的缺点,又突破了均匀水体透明度计算方法的局限性。 相似文献
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荒漠戈壁下垫面表面动量和感热湍流通量参数化研究 总被引：9，自引：0，他引：9
用合理筛选以后的野外观测资料，研究了荒漠戈壁地表湍流通量参数化的问题。首先，分析了Monin-obukhov相似函数的特征，并拟台出了其经验公式。结果表明，风速和温度相似性函数随稳定度参数的变化曲线与典型经验曲线差异较小，并且在经验曲线分布范围以内，但中性时的值有所不同。同时，还用该资料给出了动量和标量粗糙度(感热粗糙度)长度的平均值及其标量粗糙度随摩擦速度的变化关系。发现标量粗糙度的平均值大约比动量粗糙度的小一个量级，并且随摩擦速度的增大而减小，但明显比其理论预测值要大。 相似文献
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Kiafar Hamed Babazadeh Hosssien Marti Pau Kisi Ozgur Landeras Gorka Karimi Sepideh Shiri Jalal 《Theoretical and Applied Climatology》2017,130(1-2):377-389
Evapotranspiration estimation is of crucial importance in arid and hyper-arid regions, which suffer from water shortage, increasing dryness and heat. A modeling study is reported here to cross-station assessment between hyper-arid and humid conditions. The derived equations estimate ET0 values based on temperature-, radiation-, and mass transfer-based configurations. Using data from two meteorological stations in a hyper-arid region of Iran and two meteorological stations in a humid region of Spain, different local and cross-station approaches are applied for developing and validating the derived equations. The comparison of the gene expression programming (GEP)-based-derived equations with corresponding empirical-semi empirical ET0 estimation equations reveals the superiority of new formulas in comparison with the corresponding empirical equations. Therefore, the derived models can be successfully applied in these hyper-arid and humid regions as well as similar climatic contexts especially in data-lack situations. The results also show that when relying on proper input configurations, cross-station might be a promising alternative for locally trained models for the stations with data scarcity.
相似文献17.
2004年9月12日—2006年10月31日,在河北省香河县对太阳辐射（包括光合有效辐射PAR、可见光辐射VIS和总辐射Q等）、气象参数等进行了综合测量,初步得到了PAR、VIS等的变化特征。观测表明,小时累计之比PAR/Q、VIS/Q、PAR/VIS相对稳定,2004—2006年的平均值分别为2.164、0.434 mol•MJ-1和4.967 mol•MJ-1,同时它们表现出明显的日、逐日和季节变化特征,并受到水汽、气溶胶、云等因素的影响。建立了实际天气条件计算PAR、VIS小时累计值的经验公式以及PAR与VIS转换关系式,计算值与观测值符合得较好。在考虑水汽和散射因子时,PAR、VIS计算值与观测值的相对偏差分别为9.9%和10.8%。限于实际情况,也可以只考虑水汽因子的作用来计算PAR和VIS小时累计值,它们的相对偏差分别为11.1%和11.8%。对于PAR、VIS的传输和计算来说,水汽因子的作用至关重要。散射因子的作用虽然弱于水汽因子,但它的作用不容忽视。 相似文献
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Mikhail Ya Verbitsky 《Climate Dynamics》1992,7(2):105-110
A set of simple scaling formulas related to ice sheet evolution is derived from the dynamic and thermodynamic equations for ice and is used to consider two common situations: (a) when we wish to estimate potential ice sheet characteristics given the prescribed net snow accumulation over an area; and (b) when we wish to reconstruct net snow accumulation and vertical temperature difference within the ice sheet given empirical data only concerning ice sheet area and volume. The scaling formulas are applied to the present day Antarctic and Greenland ice sheets, as well as to some ancient ice sheets, and are used to estimate the potential global sea level change due to greenhouse warming. 相似文献
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This paper provides one of the first empirical studies that examine the impact of climate change adaptation practices on technical efficiency (TE) among smallholder farmers in Nepal. An adaptation index is used to explore the impact of farmers’ adaptation on TE using the stochastic frontier analysis framework. Data for six districts of Nepal representing all three agro-ecological regions (terai, hill, and mountain) were collected from a focus group discussion, a stakeholder workshop and a household survey. The survey shows that about 91% of the farming households have adopted at least one practice to minimize the adverse impacts of climate change. Empirical results reveal that adaptation is an important factor explaining efficiency differentials among farming households. Those adopting a greater number of adaptation practices on a larger scale are, on average, found to be 13% more technically efficient than those adopting fewer practices on smaller scale. The empirical results also show that average TE is only 0.72, indicating that there are opportunities for farming households in Nepal to further improve productive efficiency, on average by 28%. Other important factors that explain variations in the productive efficiency across farming households include farmer’s education level, irrigation facilities, market access, and social capital such as farmer’s participations in relevant agricultural organizations and clubs. This study provides empirical evidence to policy makers that small scale adjustments made by farmers in response to climate change impacts are effective in improving farmers’ efficiency in agriculture production. This indicates a need for farmers’ involvement in climate change adaptation planning. 相似文献
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The Extreme Forecast Index (EFI) calculations are performed using the ECMWF 2-m air temperature forecasts produced in the framework of the Subseasonal to Seasonal (S2S) Prediction Project. Four computation schemes are implemented using empirical and theoretical distributions of heat wave characteristics as well as the one-dimensional test statistics of histograms and linear interpolation formulas. Case studies (for different initial dates and regions) characterized by the significant air temperature anomalies in Northern Eurasia are performed using traditional forecast skill scores and the spatial verification methods to evaluate the efficiency of the proposed schemes for different threshold values of EFI. It is shown that the forecast quality can be considered satisfactory in most cases. The dependence of forecast skill on the intensity, spatial scales, and duration of temperature anomalies is revealed. Further studies should be carried out using larger samples based on several hydrodynamic models and the multimodel approach. 相似文献