我国蒸发力计算的气候学方法

本文根据我国的具体情况,利用10个大型蒸发池自由水面蒸发的实测资料,对计算水面蒸发力的彭曼公式作了修订。修正后的彭曼公式可用于我国水面蒸发力的计算;乘以合适的折算系数和作物系数,还可用来估算我国的自然蒸发力和农田可能蒸散。     

河西地区黑河流域绿洲蒸发力特征及其计算方法

在河西地区黑河流域地气相互作用的观测研究中，我们在不同下垫面上进行了蒸发力的测量，发现绿洲内蒸发力仅是戈壁的４４％－５６％。绿洲内蒸发力并不比湿润地区有显著增大，夜间蒸发力所占比重较大是一普遍现象，用彭曼原式和修正式计算干旱地区的蒸发力，个别月份误差较大，利用空气饱和差拟合得到的经验计算公式效果最佳。     

论陆面蒸发的计算

本文从蒸发E随降水的改变率E/r是剩余蒸发力E_0—E和降水r的函数,即E/r=f(E_0-E,r),而蒸发随蒸发力的改变率E/E_0是剩余水量,r—E和蒸发力E_0的函数,即E/E_0=φ(r-E,E_0)的考虑出发,利用量纲分析和微分方程理论确定了函数f和Φ的表述式,并由此得到根据蒸发力和降水计算陆面蒸发的公式。计算结果非常令人满意。     

我国蒸发力计算的气候学方法

目前,测定蒸发力还存在许多经济和技术上的困难,所以现在多采用气候学方法计算。彭曼综合法是其中最好的方法之一。但因彭曼公式中系数的确定是经验性的,具有局地性,直接应用于我国蒸发力的计算误差较大。本文利用我国10个蒸发实验站水面蒸发实测资料作为检验标准,逐项修正彭曼公式中各物理力量的系数,建立了适合我国实     

蒸发力的计算及其动态变化特征分析

利用彭曼公式对广西忻城站蒸发力进行了气候学计算,并对其50a动态变化趋势进行了年和生长季等不同时段的分布规律分析.     

广西自然蒸发量及应用

彭门首先(1948年)提出了蒸发力的概念。随后国内外许多学者,由于研究的对象与所处理的下垫面有差异,而出现不同的理解和定义。水文工作者把较大水体自由水面的蒸发叫蒸发力。土壤工作者把充分湿润土壤的蒸发叫蒸发力。而农业气象工作者将水分充分供应条件下的土壤蒸发及植被蒸腾之和叫作蒸发力。这些定义虽有差别,但可以找到它们的共同点,就是都以水分充分供应为前提条件的。这就是说,当下垫面水分充     

拔海高度及饱和水汽压的线性化对彭曼蒸发力计算的影响

讨论了拔海高度对彭曼蒸发力的影响方式及其影响程度随辐射平衡、风速和空气饱和水汽压差等条件的变化情况。通过对饱和水汽压进行二阶Ｔａｙｌｏｒ级数展开，研究了彭曼蒸发力公式中由于对饱和水汽压线性化处理而产生的可能误差     

拔海高原及饱和水汽压的线性化彭曼蒸发力计算的影响

讨论了拔海高度对彭曼蒸发力的影响方式及其影响程度随辐射平衡，风速和空气饱和水汽压差等条件的变化情况，通过对饱水和汽压进行二阶Ｔａｙｌｏｒ级数展开，研究了彭曼蒸发力公式中由于对饱和水汽压线性化处理而产生的可能误差。     

4种蒸发波导模型的对比与分析

蒸发波导模型常用来计算海上蒸发波导高度。为了认识当前不同蒸发波导模型之间的差异和方法,本文选取了目前使用广泛的4种蒸发波导模型(即P-J模型、Babin模型、NPS模型和伪折射率模型)进行对比和分析。本文首先探讨了在理想情况下它们对气象要素的敏感性,随后并利用我国南海近海大气层观测试验数据对比了这4种模型的蒸发波导高度计算结果。分析表明:相对湿度、风速和气—海温差的变化对4种模型的计算都有着较大的影响,特别是在不稳定层结状况下,4种模型计算得到的蒸发波导高度都随着相对湿度的增大而降低、随着风速的增大而增高。Babin模型和NPS模型计算的波导高度较为一致,伪折射率模型与前两种模型的计算结果存在差异,而P-J模型与其他3种模型存在较明显的偏差。基于南海气象数据的计算结果表明,不同蒸发波导模型在该海域蒸发波导的模拟结果略有不同,但4种模型计算得到的波导高度日变化变化趋势较为一致,波导高度极低值常出现在早晨,而极高值常出现在傍晚。     

订正小型蒸发观测资料探讨

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。     

Spatial and Temporal Variations of Atmospheric Angular Momentum and Its Relation to the Earth Length of Day

The characteristics of atmospheric-angular-momentum （AAM） and length-of-day （LOD） on different timescales are investigated in this paper, on the basis of the NECP/NCAR reanalysis data and an LOD dataset for 1962-2010. The variation and overall trend of the AAM anomaly （AAMA） at different latitudes are presented, and the relationship between AAMA and LOD is discussed. The AAMAs in different latitude regions exhibit different patterns of variation, and the AAMA in the tropics makes a dominant contribution to the global AAMA. In the tropics, the AAMA propagates poleward to the extratropical regions. It is confirmed that a downward propagation of the AAMA occurs in the lower stratosphere. Correlation analysis shows that the relationship between AAMA and LOD varies significantly on different timescales. Specifically, the tropical AAMA is positively correlated with LOD on short timescales, but they are not obviously correlated on long timescales. This indicates that the interaction between AAM and the earth＇s angular momentum follows the conservative restriction on short timescales, but the influence of the earth angular momentum on that of the atmosphere depends on the interaction process on long timescales.     

Distribution Characteristics of the Intensity and Extreme Intensity of Tropical Cyclones Influencing China

To address the deficiency of climatological research on tropical cyclones(TCs) influencing China, we analyze the distributions of TCs with different intensities in the region, based on the best-track TC data for1949–2011 provided by the Shanghai Typhoon Institute. We also present the distributions of 50- and 100-yr return-period TCs with different intensities using the Gumbel probability distribution. The results show that TCs with different intensities exert distinctive effects on various regions of China and its surrounding waters. The extreme intensity distributions of TCs over these different regions also differ. Super and severe typhoons mainly influence Taiwan Island and coastal areas of Fujian and Zhejiang provinces, while typhoons and TCs with lower intensities influence South China most frequently. The probable maximum TC intensity(PMTI) with 50- and 100-yr return periods influencing Taiwan Island is below 890 hPa; the PMTI with a50-yr return period influencing the coastal areas of Fujian and Zhejiang provinces is less than 910 hPa, and that with a 100-yr return period is less than 900 hPa; the PMTI with a 50-yr return period influencing the coastal areas of Hainan, Guangdong, and the northern part of the South China Sea is lower than 930 hPa,and that with a 100-yr return period is less than 920 hPa. The results provide a useful reference for the estimation of extreme TC intensities over different regions of China.     

CMA-GFS云预报的偏差分布特征

利用2021年3月—2022年2月ERA5再分析数据云量、云水凝物对中国气象局研发的全球数值预报系统CMA-GFS同期云量产品和由云量、云水凝物产品计算的云发生、云水凝物积分的偏差特征进行诊断评估, 初步探讨了CMA-GFS云预报偏差存在的可能原因。结果显示:CMA-GFS云量、云水凝物的分布较为合理, CMA-GFS能够描绘全球云量、云水凝物的分布特征, 并能够反映季节特征;CMA-GFS预报高云和中云的云量偏差大于低云的云量偏差, 而高云和中云的云量均方根误差较低云偏小, 说明模式高云和中云的预报稳定性优于低云;与ERA5再分析数据相比, CMA-GFS液相水凝物积分以负偏差为主, 冰相水凝物积分以正偏差为主;云量、云水凝物的偏差在不同地区成因不同, 在热带地区的偏差与对流参数化和微物理方案不协调有关, 在南北半球中高纬度地区的偏差与相对湿度偏差相关。     

Spatial and Temporal Variations of Atmospheric Angular Momentum and Its Relation to the Earth Length of Day

The characteristics of atmospheric-angular-momentum(AAM) and length-of-day(LOD) on different timescales are investigated in this paper,on the basis of the NECP/NCAR reanalysis data and an LOD dataset for 1962-2010.The variation and overall trend of the AAM anomaly(AAMA) at different latitudes are presented,and the relationship between AAMA and LOD is discussed.The AAMAs in different latitude regions exhibit different patterns of variation,and the AAMA in the tropics makes a dominant contribution to the global AAMA.In the tropics,the AAMA propagates poleward to the extratropical regions.It is confirmed that a downward propagation of the AAMA occurs in the lower stratosphere.Correlation analysis shows that the relationship between AAMA and LOD varies significantly on different timescales.Specifically,the tropical AAMA is positively correlated with LOD on short timescales,but they are not obviously correlated on long timescales.This indicates that the interaction between AAM and the earth's angular momentum follows the conservative restriction on short timescales,but the influence of the earth angular momentum on that of the atmosphere depends on the interaction process on long timescales.     

后置群体评价方法在天气预报决策中的应用

在应用各种预报方法作每日的天气预报时，常遇到的各种预报方法的结果不一致的情形，这时需集各预报结果为一体作为群体决策意见，作者介绍了后置群体评价方法在天气预报决策中的具体应用，用该方法进行决策，取得了较理想的效果。     

强风暴个例电荷结构及云闪放电差异的数值模拟

利用耦合电过程的冰粒子分档模式对长春地区两个降雹型和非降雹型强风暴个例的闪电特征进行了模拟和对比分析。结果表明,在雷暴云的初始发展期,由于上升气流较弱,两者电荷分布相似,均表现为弱的正偶极结构。随着云体不断发展,两者电荷分布开始表现出差异:降雹型个例中的上升气流较强,风切变较大,过冷水能被携带到较高的高度,冰相粒子也能被带到较高处或在较高处继续增长,使得不同区域均存在冰相粒子含量中心。因此,冰相粒子的发生范围不同、环境参数不同及荷电符号不同的非感应起电过程,形成多个电荷中心,电荷结构易出现多层分布。在不同的发展时期电荷结构均呈现出不同的形态,放电既可能在上升气流区触发,也可能在气流辐散区触发。相对而言,非降雹型个例中的上升气流较弱,风切变较小,冰相粒子的分布较规则,非感应起电过程较均匀,从而导致电荷分布始终较均匀。不同发展时期的电荷结构都相对有规则,满足放电条件的位置具有一定的相似性。     

The Uncertainty of Mesoscale Numerical Prediction of Heavy Rain in South China and the Ensemble Simulations?

In the context of non-hydrostatic MM5 version we have explored the impact of convective parameterization schemes on uncertainty in mesoscale numerical prediction of South China heavy rain and mesoscale heavy rainfall short-range ensemble simulation by using two kinds of physics perturbation methods through a heavy rain case occurring on June 8, 1998 in Guangdong and Fujian Provinces. The results show the physical process of impacts of convective schemes on heavy rainfall is that different latent heat of convective condensation produced by different convective schemes can make local temperature perturbation, leading to the difference of local vertical speed by the intrinsic dynamic and thermodynamic processes of atmosphere,and therefore, making difference of the timing, locations and strength of mesh scale and subgrid scale precipitation later. New precipitations become the new source of latent heat and temperature perturbation,which finally make the dynamic and thermodynamic structures different in the simulations. Two kinds of methods are used to construct different model version stochastically. The first one is using different convective parameterization and planetary boundary layer schemes, the second is adjusting different parameters of convective trigger functions in Grell scheme. The results indicate that the first ensemble simulations can provide more uncertainty information of location and strength of heavy rainfall than the second. The single determinate predictions of heavy rain are unstable; physics ensemble predictions can reflect the uncertainty of heavy rain, provide more useful guidance and have higher application value.Physics ensembles suggest that model errors should be taken into consideration in the heavy rainfall ensembles. Although the method of using different parameters in Grell scheme could not produce good results, how to construct the perturbation model or adjust the parameter in one scheme according to the physical meaning of the parameter still needs further investigation. The limitation of the current study is that it is based on a single case and more cases will be addressed in the future researches.     

How Does the Partitioning of Evapotranspiration and Runoff between Different Processes Affect the Variability and Predictability of Soil Moisture and Precipitation？

Water stored as part of the land surface is lost to evapotranspiration and runoff on different time scales,and the partitioning between these time scales is important for modeling soil water in a climate model.Different time scales are imposed on evapotranspiration primarily because it is derived from different reservoirs with different storage capacities, from the very rapid evaporation of canopy stores to the slow removal by transpiration of rooting zone soil moisture. Runoff likewise ranges in time scale from rapid surface terms to the slower base-flow. The longest time scale losses of water determine the slow variation of soil moisture and hence the longer time scale effects of soil moisture on precipitation. This paper shows with a simple analysis how shifting the partitioning of evapotranspiration between the different reservoirs affects the variability of soil moisture and precipitation. In particular, it is concluded that a shift to shorter time scale reservoirs shifts the variance of precipitation from that which is potentially predictable to unpredictable.     

Impact of Climate on Tourist Demand

Tourism, being volatile and situation-specific, is responsive to climate change. A cross-section analysis is conducted on destinations of OECD tourists and a factor and regression analysis on holiday activities of Dutch tourists, to find optimal temperatures at travel destination for different tourists and different tourist activities. Globally, OECD tourists prefer a temperature of 21 °C (average of the hottest month of the year) at theirchoice of holiday destination. This indicates that, under a scenario of gradual warming, tourists would spend their holidays in different places than they currently do. The factor and regression analysis suggests that preferences for climates at tourist destinations differ among age and income groups.     

四川地区降水幂律指数研究

基于四川地区5个站点1960~2004年的日降水观测资料,对其在等级分析的基础上探讨了幂律分布的规律,结果如下:(1)这5个站点日降水存在的一个共同特征—幂律尾分布,且不同等级的降水量对应不同的幂律尾指数,在一定程度上反映了不同雨型具有不同的气候背景和物理机理;(2)小雨幂指数随时间变化很小,中雨幂指数随时间变化较大,从80年代末期开始,四川盆地西部与南部地区中雨幂指数增加,中雨降水减少,川西高原、四川盆地东部与北部地区中雨幂指数减小,中雨降水增加。因此,中雨的变化可能会引起总降水量的变化。