非地转湿Q矢量的改进及其应用

在完全考虑非绝热加热项作用的前提下,从原始方程出发,推导出改进后的非地转湿Q矢量(Q^q),以及用其散度作强迫项的ω方程,将其应用于一次梅雨锋暴雨诊断分析,结果表明:改进后的非地转湿Q矢量对同时刻地面降水的反映能力较岳彩军改进的湿Q矢量(Q^M)、原非地转湿Q矢量(Q^*)、非地转Q矢量(Q#)有显著的提高;在整个梅雨锋暴雨过程中,500hPa高度上的Q^q矢量散度辐合场的辐合强度及其辐合中心位置对同时刻的降水强度及雨区位置有非常好的指示作用;Q^q矢量的垂直分布揭示了次级环流的方向和强弱,暴雨位于次级环流的上升支附近。     

HⅢ(2n)中元素的一种标准化表示

给出HⅢ(2n)中元素的一种标准化表示,HⅢ(2n)={Z∈C^2n×2n|1/2(Z+Z'')>0,ZJ=JZ''},J=0 I_n-I_n 0,1/2(Z+Z)>0表示矩阵1/2(Z+z'')是正定的。     

二阶奇异动力系统的非平凡周期解

应用Leray-Schauder非线性二择一原理研究二阶动力系统x+k²x=f(t,x)+e(t)非平凡周期解的存在性,其中0<k<π/T,f∈C((R/TZ)×R^N\{0},R^N)在原点具有排斥的奇性.不需要任何的强制性条件,既可以处理强奇性,也可以处理弱奇性.     

利用LAP-3000型风廓线雷达资料对深圳地区湍流耗散率特征的研究

利用2010年1-2月深圳LAP3000型风廓线雷达资料, 对湍流耗散率进行了估算, 针对典型晴天条件下的湍流耗散率ε、折射率结构常数C₂ⁿ、水平风速和风切变, 分析了其时空变化特征。得出如下结论: (1) 深圳地区低空大气ε的量级在10^-7~10^-1 m^-2·s^-3之间, 与理论模拟值基本一致; (2) 时间分布特征为, 2 km以下ε有很明显的日变化特征, 夜晚和上午ε较大, 下午及傍晚减少;(3) 空间分布特征表现为, ε随高度大致呈递减分布;ε量级达10^-2.5 m²·s^-3所在高度可作为深圳地区2010年1月14-15日边界层顶高度的判断依据。     

一类非线性Volterra积分不等式

本文简要讨论Gronwall不等式的研究进展,并给出关于如下的一类非线性Volterra积分不等式的一个结果：w(u(t))≤g(t))+∑_i=1ⁿ∫_αi(t0)^α_i(t)f_i(t,s)∏_j=1^mH_ij(u(s))G_ij(max_s-h≤ξ≤s u (ξ))ds.     

云南一次持续性暴雨过程的非地转湿Q*

应用非地转湿Q^*,对2001年5月31日至6月2日发生在云南的持续性暴雨天气过程进行诊断分析。结果表明,非地转湿Q矢量辐合区是暴雨发生的有利区域;非地转湿Q矢量的垂直分布反映了次级环流的方向和强弱,云南的暴雨落区位于次级环流的上升支附近。     

QINGHAI-XIZANG SURFACE LONG-WAVE RADIATION PARAMETERIZATION WITH ITS CLIMATIC CALCULATION*

In the context of August 1982- July 1983 radiation balance data of the Qinghai-Xizang Plateau, detailed study is made of the relation between the active-surface temperature and surface temperature, proposing two parameterization schemes on surface long-wave radiation(SLWR)of the form U=kδσ(T₀+273)⁴ and U=δσ[(T₀+273)⁴+△T)]⁴, where k and △T are indicated by parameterization equations, separately, others being in conventional notation. Retrieved verification shows the two formulae to be of the same fitting accuracy with the mean relative error of 3.6% and suitable for computing instantaneous and mean flux density, alongside analyzed daily and annual variations of k and △T. Eventually. SLWR in the target area is investigated and its climatic characteristics examined.     

湿Q矢量散度场与ω场的比较

结合1991年7月5日20时至6日20时一次典型的江淮梅雨锋暴雨过程实况资料,系统、细致地比较分析了实时分析的湿Q矢量散度场与同时次改进后的MM4(MMM4)模式实时分析输出场之间的差异。结果表明:在整个梅雨锋暴雨过程中,湿Q矢量散度辐合场与同时刻地面雨区之间的对应关系较ω场优越;700hPa湿Q矢量散度辐合区对同时刻地面降水场有指示作用,尤其在梅雨锋暴雨的发展阶段及强盛时期,它对实际降水的落区及强度指示作用更为明显;MMM4模式中关于垂直速度计算的方案有待进一步改进。     

Relationship between Net Radiation and Broadband Solar Radiation in the Tibetan Plateau

The characteristics of net radiation (R_n)(0.3--10 μm) in Lhasa and Haibei in the Tibetan Plateau were analyzed based on long-term in-situ measurements of surface radiation data. The monthly average of daily R_n reached a minimum during the winter period followed by an increase until May and then a decline until January. This variation is consistent with solar activity. The annual mean daily total R_n values were 0.92 MJ m^-2 d^-1 and 0.66 MJ m^-2d^-1 in Lhasa and Haibei, respectively. A relationship between R_n and broadband solar radiation (R_s) was demonstrated by a good linear correlation at the two sites. R_n can be an accurate estimate from R_s. The estimated R_n values were similar to the observed values, and the relative deviations between the estimates and measurements of R_n were 2.8% and 3.8% in Lhasa and Haibei, respectively. The application of the R_n estimating model to other locations showed that it could provide acceptable estimated R_n values from the R_s data. Furthermore, we analyzed the influence of clouds on R_n by different clear index (K_s), defined as the ratio of R_s to the extraterrestrial solar irradiance on a horizontal surface. The results indicate that more accurate results are associated with increased cloudy conditions. The influence of the albedo was also considered, but its inclusion in the model resulted in only a slight improvement. Because surface albedo is not usually measured, an expression based solely on global solar radiation could be of more extensive use.     

利用雷达作台风0～3h雨量等级预报

通过对1989～1992年台风影响浙江期间,杭州数字化雷达回波及对应的地面58个气象站和156个水文站自记1h雨量资料,进行了统计分析,得到在浙江仅有台风单一系统引起降水时,杭州数字化雷达回波强度Z与雨强I.根据Z=A·I^b关系得出A、b系数在不同探测范围的值,以得到Z与I关系,并结合雷达回波的移动情况,制作了浙江省台风0～3h雨量等级预报。     

下沉气流对Z-I关系的影响

采用伽玛分布形式的雨滴谱表达式，讨论了下沉气流W对Z－I关系的影响。发现随着W（向下为正）增大，关系式Z＝AI^b中系数A值减小,b值增大。利用地面实测雨滴谱资料计算出不同下沉气流下Z、I后回归得到的A、b值，以及根据由平均谱拟合得到的伽玛分布参数计算出A、b值，它们随W改变的变化趋势，均与理论分析结果一致。还讨论了环境气压场p对Z－I关系的作用，气压减小时，A值减小，b值增大，但变化不如W影响时的变化影响。此外，结合实测雨滴谱资料，分析了雨滴平均谱特征以及相关物理量的演变过程。     

Q矢量的改进与完善

在完全考虑非绝热加热项潜热作用的前提下，从原始方程出发，推导出改进后的湿Q矢量(以下记为Q^M)的表达式以及用其散度作强迫项的ω方程，并结合一次梅雨锋暴雨天气过程将改进前、后的湿Q矢量诊断能力进行比较，结果发现：(1)改进后的湿Q矢量对同时刻的地面降水的反映能力较原湿Q矢量(Q^*)有显著的提高。(2)在整个梅雨锋暴雨过程中，600hPa高度上的改进后的湿Q矢量散度辐合场的辐合强度及其辐合中心的位置对同时刻的地面实际降水的强度及雨区位置都有非常好的指示作用。     

Influence of drizzle on Z–M relationships in warm clouds

This paper addresses the sensitivity of the relationships between radar reflectivity (Z) and liquid water content (M) for liquid water clouds to microphysical drizzle parameters by means of simulated radar observation at a frequency of 3 GHz of modeled cumulus clouds. A power law relationship for non drizzling clouds with water content as high as 3 gm^− 3: Z_c = 0.026 M_c^1.61 is numerically derived and agreed with previous empirical relationships relative to cumulus and stratocumulus. This relationship is then used to explore the influence of drizzle on the correlation between radar reflectively and water content. Due to their large diameters with respect to cloud droplets, drizzle sized drops dominate radar reflectivity but do not carry the cloud water content so that reflectivity and liquid water content are expected to be not correlated in clouds containing drizzle. It is shown that for congestus or extreme congestus cumuli, microphysical conditions for which the Z_c–M_c relationship can be used with a tolerance of 5 and 10% are provided whereas for humilis or mediocris cumuli, the presence of drizzle breaks down the Z_c–M_c relationship whatever the situations.     

Biogenic emissions from Pinus halepensis: a typical species of the Mediterranean area

Volatile organic compounds (VOCs) emissions by vegetation present in the Mediterranean area are not well known. They may contribute with anthropogenic VOC emissions to the tropospheric ozone formation that reaches important level in the European Mediterranean region. The present work, carried out as part of the European ESCOMPTE project «fiEld experimentS to COnstrain Models of atmospheric Pollution and Transport of Emissions», adds a new contribution to the inventory of the main natural hydrocarbons sources likely to participate in the ozone production. The corresponding measurement campaign was conducted in La Barben, a site close to Marseilles (France), with the aim to quantify the terpenic emission pattern and the behaviour of Pinus halepensis, an important Mediterranean species slightly studied.The determination of biogenic emissions from P. halepensis was done by the enclosure of an intact branch in a Teflon cuvette. Main emitted monoterpenes were β trans-ocimene and linalool. The total monoterpenic emission rates thus recorded were found to reach maximum values around 30 μg g_{dry weight}⁻¹ h⁻¹. The normalized emission rates calculated at 30 °C and 1000 μmol m⁻² s⁻¹ with Guenther's algorithm was 14.76, 8.65 and 4.05 μg g_{dry weight}⁻¹ h⁻¹, respectively, for the total monoterpenes, β trans-ocimene and linalool.     

气候变化对云南省小粒咖啡适生区的影响

为揭示气候变化对云南省小粒咖啡适生区的影响，基于最大熵（MaxEnt）模型，结合小粒咖啡物种分布数据、环境变量数据，构建云南省小粒咖啡适生区评估及预测模型，对当前气候条件下小粒咖啡在云南省的适生区进行评估，并对未来气候条件下，小粒咖啡在云南省的适生区进行预测，再对预测结果进行对比分析。结果显示:（1）构建的最大熵模型能够较精确地用于小粒咖啡在云南省适生区的评估和预测，当前气候条件下，评估模型的训练集与测试集的AUC （Area under ROC Curve）值均为0.941，达到评估结果为极好的标准。（2）影响云南省小粒咖啡种植的主导环境因子依次为11月平均最高气温、7月降雨量、海拔高度、2月平均最低气温、10月降雨量、坡度和最冷月最低气温，共占总贡献率的91.4%。（3）当前气候条件下，小粒咖啡的适生区主要分布在滇西、滇西南以及滇南的保山、德宏、普洱、临沧、西双版纳等地区，总适生区约为116300 km2，占云南省国土面积的29.51%，且总体上，高适生区外围分布中适生区，中适生区外围分布低适生区。RCP4.5、RCP8.5情景下，小粒咖啡总适生区的面积分别约为98300、69700 km2，分别占云南省国土面积的24.95%、17.69%，两种排放情景下小粒咖啡总适生区面积分别减少了18000、46600 km2，国土面积占比分别减少了4.56%、11.82%，且总适生区的质心均由东南向西北方向移动，与RCP4.5情景相比，RCP8.5情景的移动距离更远。（4）未来气候变化将会导致小粒咖啡在云南省的总适生区面积减小，总适生区的质心位置向海拔更高与纬度更高的方向移动，且高碳排放情景下这种变化幅度更大。      

The influence of CCN spectra and updraft velocities on the validity of the b parameterization of the condensation process

A detailed parcel model of condensational droplet growth, including surface tension and dissolved salts effects, is used for studying the validity of a parameterization based on the simplified droplet growth equation, the b² scheme. In the b² scheme, spectra are derived from the droplet distribution at the activation level, and the liquid water mixing ratio using a translation of the initial spectrum in the r² scale. Spectra derived from the detailed model are thus compared to translated spectra. Four simplified CCN distributions are tested for updraft velocities in the range of 0.5 m/s to 5.0 m/s. It is shown that the b² scheme is suitable for use in cloud models, except when the proportion of large nuclei in the CCN distribution is extremely high.     

Multiple pulses in dE/dt and the fine-structure of E during the onset of first return strokes in cloud-to-ocean lightning

We have analyzed the fine-structure of 131 electric field (E) waveforms that were radiated during the onset of first return strokes in cloud-to-ocean lightning. The dE/dt waveforms were recorded using an 8-bit waveform digitizer sampling at 100 MHz, and the E waveforms were sampled at 10 MHz using a 10-bit digitizer. 49 (or 37%) of the dE/dt waveforms contain one or more large pulses within ± 1 μs of the largest (or dominant) peak in dE/dt, i.e. within an interval from − 1 μs to + 1 μs, where t = 0 μs is the time of the dominant peak, and 37 (or 28%) have one or more large pulses in the interval from 4 μs before to 1 μs before the dominant peak, i.e. − 4 μs to − 1 μs, and only the dominant peak within ± 1 μs . We give statistics on the amplitude and timing of dE/dt pulses that are near the dominant peak, and we show how the presence of these pulses adds considerable fine-structure to the shape of E_int, the integrated dE/dt waveform, on a time-scale of tens to hundreds of nanoseconds. This fine-structure includes fast pulses near the beginning of the slow front, large pulses and shoulders within the slow front and during the fast-transition, and very narrow peaks in E_int. Our overall conclusion is that the electromagnetic environment near the point(s) where lightning leaders attach to the surface is often more complicated than what would be produced by a single current pulse propagating up a single channel at the time of onset.     

21世纪Q矢量在中国多种灾害性天气中应用研究的进展

伴随着Q矢量理论的完善与发展,人们也对Q矢量的分析方法开展了广泛的应用研究,不仅用于诊断分析研究暴雨、台风、暴雪、强对流及沙尘暴等多种灾害性天气的成因,同时在天气预报工作中也扮演着越来越重要的角色.对进入21世纪以来中国对Q矢量的应用研究工作进行全面、系统地回顾与总结,并对未来关于Q矢量的应用研究工作进行了讨论与展望.     

Finite-amplitude, neutral baroclinic eddies and mean flows in an internally heated, rotating fluid: 2. Effects of spatially varying N

The analytical model of finite-amplitude, quasi-geostrophic ‘free mode’ baroclinic eddies and mean zonal flows in a Cartesian channel, presented recently by Read, is extended to take account of vertical variations in the buoyancy frequency N. A series of exact solutions is presented to illustrate the effect of monotonically varying static stability on the structure and properties of the flow. The analytical solutions are then compared with a corresponding series of numerical simulations of steady wave flows in a rotating fluid annulus subject to internal heating and sidewall cooling. By suitable choices of internal heating distributions and boundary conditions, several different forms of N² profile could be obtained in the simulated flows, in which N² was concentrated to a greater or lesser extent towards the upper boundary. The resulting steady flows exhibited strong qualitative similarities in their structure and dependence upon the form of N²(z) to that of the analytical solutions when realistic profiles of N² were included in the latter, especially when an equivalent-barotropic component was included, although the latter component is unable to satisfy the simplest (internal jet) form of horizontal boundary condition as usually applied to Rossby waves.The relatively weak, though crucially important, forcing and dissipation processes in the annulus are examined using approximate quasi-geostrophic diagnostics of the major terms in the budget of potential enstrophy for the numerical simulations. Internal heating is found to be the major source of potential enstrophy for the mean zonal flow, solely by virtue of the variation of N² with height, but has only a minor direct effect upon the eddy flow component. Because of the presence of critical layers in the flow, all non-linear terms (including the third-order potential enstrophy flux divergence) are found to be significant in certain regions. Some implications for the value and applicability of EP flux diagnostics are discussed. Potential enstrophy budgets for horizontal regions enclosed by geostrophic streamlines are used to shed further insight into the maintenance of the flow against ‘friction’, and on the form of the potential vorticity-streamfunction relationship. Some implications of the results for other systems of geophysical interest are also discussed.