首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 171 毫秒
1.
晴天太阳总辐射的参数化及气候计算   总被引:6,自引:0,他引:6  
在文献[1]基础上,根据北京、拉萨等站1735次实测资料,进一步讨论了应用别尔梁德理论式Qo=Iosinh/1+fm作晴天总辐射参数化的可能性。提出了f 的新参数化方案。与原方案相比,保持较高拟合精度外,新方案的普适性更好。按本方案计算的各地晴天总辐射廓线形式,与国内外地面和飞艇探测结果一致。对青藏高原6站所作晴天总辐射气候计算也与实例值相符。  相似文献   

2.
给出带有m-1项断裂项n+m阶Taylor定理余项中θ的渐近估计,其估计式为θ=m+nn-1m+o(x)。利用该估计式将Taylor定理推广为f(x)=∑n-1k=0f(k)(0)k!xk+f(n)〔θnx〕xnn!+Rn,其中余项Rn=〔1-(1+nm+n)θm〕f(m+n+1)(ξ)(m+n+1)!xm+n+1。最后举例说明该推广在近似计算中的优越性。  相似文献   

3.
给出带有m-1项断裂项n+m阶Taylor定理余项中θ的渐近估计,其估计式为θ=(m+n n)^1/m+o(x)。利用该估计式将Taylor定理推广为f(x)=n-1∑k=0f^(k)(0)/k!x^k+f(n)(θnx)x^n/n!+Rn,其中余项Rn=(1-(1+n/m+n)θm)f^(m+n+1)/(m+n+1)!x^m+n+1。最后举例说明该推广在近似计算中的优越性。  相似文献   

4.
青藏高原地表长波辐射参数化及其气候计算   总被引:5,自引:1,他引:5  
根据1982年8月至1983年7月青藏高原辐射平衡资料,详细讨论了该地区活动面温度与地表温度的关系,提出了两种计算地表长波辐射的参数化方法U=kδσ(T0+273)^4和U=δσ[(T0+273)+ΔT]^4。经反演检验,两式的拟合精度相同(均为3.6%),并适用于作瞬时和平均通量密度计算,文中还就k、ΔT的日、年变化作了分析,计算并讨论了青藏高原地表长波辐射的气候特征。  相似文献   

5.
西部山区总辐射气候学计算及分布   总被引:11,自引:1,他引:11  
根据西部山区太阳总辐射的实测资料分析,指出,西部山区总辐射的气候学计算必须考虑日照,水汽分布及海拔高度的影响。为此研制了适宜于西部山区的总辐射气候学计算公式Q=Q0(a+bs1+cs1^2),进而讨论了西部山区总辐射的时,空分布。  相似文献   

6.
中国地表潜热的气候计算及其分布   总被引:2,自引:0,他引:2  
从整理全国仅有的6个热平衡站实测梯度资料着手,初步讨论了我国地表潜热的气候计算方法,提出新的潜热气候计算式 LE=14.73exp(0.5H+0.069e)(1+0.013△T)u^-0.16 据此计算出全国各站的月,年平均潜热通量密度并分析了其在全国的地理分布和年变化特点,得出一些有意义的结果。  相似文献   

7.
设Ω={x∈R^n|hi(x)=0,i=1,…,ligi(x)≤0,j=1,…,m}为一无界集合f(x)在Ω下方有界但达不到下确界。对f(x)在Ω的某一点处取得广义极小值给出了一个必要条件,并对f(x)为凸函数时给出了一个充分条件。  相似文献   

8.
利用Krasnonelskii不动点定理,研 究了二阶微分方程组 -u″=a(t,w)f(u,v), -v″=b(t,w)g(u,v), -w″=h(t,u,v), u(0)=u(1)=v(0)=v(1)=   w(0)=w(1)= { 0 的边值问题在某些条件下正解的存 在性.  相似文献   

9.
利用准地转正压涡度方程全球谱模式,以对三个行星波准共振相互作用作了数值试验,取两类准共振波矢:(1)K1+K2+K3=0,ω1+ω2+ω3+△ω;(2)k1+k2+k3=0,l1+l2+l3=△l,ω1+ω2+ω3=0,分别积分90d,得到了一些重要结果:(1)纬向波数k=1,2,3的三个行星波存在着较强的波-波相互作用;(2)由于波波相互作用,这三个行星波存在着周期为20-45d左右的低频振荡,  相似文献   

10.
该文利用TOGA-COARE强化观测期(IOP)所获得的辐射观测资料(1992年11月10日—1993年2月18日),对考察点(2°15′S,158°00′E)的辐射分量进行了分析,其中包括总辐射、直接辐射、散射辐射、海表长波辐射、大气逆辐射、海表反射辐射及其反照率、净辐射及有效辐射。结果表明:和其它地区(如高原)比较,观测点的总辐射、直接辐射均很强;反射率小,晴天平均为0.04—0.05,阴天为0.06—0.08;海表长波辐射大而日变化小,大气逆辐射强而日变化大;有效辐射小而净辐射大。  相似文献   

11.
青藏高原五道梁地区湍流输送特征的研究   总被引:25,自引:11,他引:25  
祁永强  王介民 《高原气象》1996,15(2):172-177
根据1994年6-7月在青藏高原五道梁地区的湍流脉动观测资料,分析了该地区近地层能量平衡、感热和谱热的日变化及湍流强度和端流谱特征。结果表明:晴天该地区近地层能量基本平衡,各能量分量的日变化与常情况相同;白天感热通量的输送占主导地位,潜热通量占次要地位,符合半干旱的一般特征。  相似文献   

12.
本文从理论上推导了流体介质中球体降速υ随其半径r的变化形式υ=α。其中a、b为简化运动方程时引进的二个待定常数,由大气中水滴降速的实测资料确定,其值为a=0.53563、b=1.37358。由此式计算的最大相对误差为24%。比较了这一半理论公式与他人经验公式各自的特点。推荐了三组形如υ=A之新的统计公式,它们分别将r=0~2900μm分为三、四、五段,对应的计算最大相对误差分别为11%、7%、4%。  相似文献   

13.
消雷器电晕电流的测量和理论分析   总被引:1,自引:1,他引:0  
言穆弘  华贵义 《高原气象》1995,14(1):121-128
迄今为止,“消雷器”产生的电晕电流及其“消雷”机理尚有争论。本文利用一种“消雷器”实测电晕电流和电场强度,并根据一次闪电后地面电场恢复特征,从理论上估算了恢复时段内电晕电流密度。结果表明,即使在电场恢复到较为稳定的时刻,测量值仍比理论值约大一个量级,而理论值和地面自然尖端产生的电晕电流在量级上相当,“消雷器”产生的电晕电流不会高于自然尖端的作用。此外,“消雷器”结构(强局地表面电场、较大电晕有效面  相似文献   

14.
赵强  刘式适 《气象学报》2001,59(2):242-245
文中利用合理的赤道 β平面近似方程组研究 β效应和地球旋转向量水平分量 (即Coriolis力分量 f*=2 Ω cosφ)共同作用下低纬度大气波动的特征。定性结果分析表明 ,若扰动与纬度有关 (混合 Rossby-重力波和 Rossby波 ) ,f*虽然不影响波动传播的频率特征 ,但修改其决定波动经向结构的振幅。如果扰动与纬度无关 (Kelvin波 ) ,则 f*的影响消失 ,这与 f*- f平面上波动的情况显然不同。  相似文献   

15.
A simplified scheme of the generalized layered radiative transfer model   总被引:1,自引:0,他引:1  
In this paper, firstly, a simplified version (SGRTM) of the generalized layered radiative transfer model (GRTM) within the canopy, developed by us, is presented. It reduces the information requirement of inputted sky diffuse radiation, as well as of canopy morphology, and in turn saves computer resources. Results from the SGRTM agree perfectly with those of the GRTM. Secondly, by applying the linear superposition principle of the optics and by using the basic solutions of the GRTM for radiative transfer within the canopy under the condition of assumed zero soil reflectance, two sets of explicit analytical solutions of radiative transfer within the canopy with any soil reflectance magnitude are derived: one for incident diffuse, and the other for direct beam radiation. The explicit analytical solutions need two sets of basic solutions of canopy reflectance and transmittance under zero soil reflectance, run by the model for both diffuse and direct beam radiation. One set of basic solutions is the canopy reflectance αf (written as α1 for direct beam radiation) and transmittance βf (written as β1 for direction beam radiation) with zero soil reflectance for the downward radiation from above the canopy (i.e. sky), and the other set is the canopy reflectance (αb) and transmittance βb for the upward radiation from below the canopy (i.e., ground). Under the condition of the same plant architecture in the vertical layers, and the same leaf adaxial and abaxial optical properties in the canopies for the uniform diffuse radiation, the explicit solutions need only one set of basic solutions, because under this condition the two basic solutions are equal, i.e., αf = αb and βf = βb. Using the explicit analytical solutions, the fractions of any kind of incident solar radiation reflected from (defined as surface albedo, or canopy reflectance), transmitted through (defined as canopy transmittance), and absorbed by (defined as canopy absorptance) the canopy and other properties per  相似文献   

16.
Source areas for scalars and scalar fluxes   总被引:19,自引:2,他引:19  
The spatial resolution of meteorological observations of scalars (such as concentrations or temperature) and scalar fluxes (e.g., water-vapour flux, sensible heat flux) above inhomogeneous surfaces is in general not known. It is determined by the surface area of influence orsource area of the sensor, which for sensors of quantities that are subject to turbulent diffusion, depends on the flow and turbulence conditions.Functions describing the relationship between the spatial distribution of surface sources (or sinks) and a measured signal at height in the surface layer have been termed thefootprint function or thesource weight function. In this paper, the source area of levelP is defined as the integral of the source weight function over the smallest possible domain comprising the fractionP of the total surface influence reflected in the measured signal. Source area models for scalar concentration and for passive scalar fluxes are presented. The results of the models are presented as characteristic dimensions of theP=50% source areas (i.e., the area responsible for 50% of the surface influence): the maximum source location (i.e., the upwind distance of the surface element with the maximum-weight influence), the near and the far end of the source area, and its maximal lateral extension. These numerical model results are related directly to non-dimensional surface-layer scaling variables by a non-linear least squares method in a parameterized model which provides a user-friendly estimate of the surface area responsible for measured concentrations or fluxes. The source area models presented here allow conclusions to be made about the spatial representativeness and the localness (these terms are defined in the text) of flux and concentration measurements.  相似文献   

17.
王宗皓 《气象学报》1981,39(3):387-397
天气数值预报工作中所用的初始方程显式差分格式,时间步长取得很短,实际应用很不方便。比如,空间步长取300公里,时间步长只能用10分钟。本文提出一种新型显式差分格式,其计算稳定性不受时间步长(τ)和空间步长(d)大小的限制,由|λe|τ/d(e=1,2,3)的整数部分me=[|λe|τ/d],控制执行“浮动”计算,保持计算稳定。这种差分格式曾用104电子计算机作检验计算,空间步长用25公里,时间步长取20分钟,计算过程稳定,结果精度较高,可与文献[1]中的结果相比较。这表明,初始方程的差分计算,适当延长时间步长是有可能的。  相似文献   

18.
采用实验室观测和DDA法理论计算,分别获得了球锥扁椭球形冰粒对3.2、5.6和10.7cm三种波长极化波的后向散射特性数据。结果表明,测量资料和计算数据具有很好的一致性。球锥扁椭球形冰粒的后向散射截面大小不仅依赖于其尺寸(等容半径)而且受其形状影响,“差反射率雷因子ZDR”与粒子形状参数“水平-垂直尺度比”呈很好的线性正相关。这是利用双偏振雷达探测识别球锥扁椭球形冰雹的依据。  相似文献   

19.
Assessment of the radiative forcing of aerosols in models still lacks sufficient input data for aerosol hygroscopicity. The light scattering enhancement factor [ f(RH, λ)] is a crucial parameter for describing aerosol hygroscopic growth properties.In this paper, we provide a survey of f(RH, λ) studies in China for the past seven years, including instrument developments of humidified nephelometers, ambient f(RH, λ) measurements in China, f(RH, λ) parameterization schemes, and f(RH, λ)applications in aerosol measurements. Comparisons of different f(RH, λ) parameterizations are carried out to check their performance in China using field measurement datasets. We also summary the parameterization schemes for predicting f(RH, λ)with aerosol chemical compositions. The recently developed methods to observe other aerosol properties using f(RH, λ)measurements, such as calculating the aerosol hygroscopicity parameter, cloud condensation nuclei number concentration,aerosol liquid water content, and aerosol asymmetry factor, are introduced. Suggestions for further research on f(RH, λ) in China are given.  相似文献   

20.
东亚海陆热力差指数与中国夏季降水的关系   总被引:9,自引:0,他引:9  
定义了东亚海陆热力差指数(ILSTD),讨论了它与东亚夏季风的强弱年际变化及夏季降水的关系。结果表明:该海陆热力差指数较好地反映了我国东部季风区夏季降水的异常变化、强海陆热力差指数年,华北地区降水偏多,长江、淮河流域明显干旱;弱海陆热力差指数年,长江,淮河流域降水又异常偏多。TLSTD的异常变化对影响我国东部季风区降水的大气环流型具有较强的识别力,尤其是对夏季西太平洋副热带高压的位置与强度的识别。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号