用单多卜勒雷达确定中尺度气旋环流中心及最大风速半径

首先给出具有 Ｒａｎｋｉｎｅ 模式的中尺度气旋的模拟多卜勒径向速度图,然后利用多卜勒雷达观测的径向速度与实际气流间的几何关系,提出一种确定近似轴对称的中尺度气旋中心及最大风速半径的方法。     

苹果Ⅱ微机对713天气雷达信息处理的应用

本文主要介绍由713天气雷达对某一固定地点气象回波进行离散取样,在苹果Ⅱ型微机上实现信号“时域”和“频域”上涨落谱的高分辨图形显示的方法,并且探讨了这些显示结果的某些实际应用。如对雷达视频积分器效果的直观检验等等。此外对713天气雷达视频积分器独立取样问题也做了探讨,得到了对应不同多卜勒速度方差情况下713天气雷达的独立取样时间。     

远旁瓣引起的杂波干扰

分析了偏角馈入抛物面天线远旁瓣回波产生的机理,并经实验验证了远旁瓣回波的存在。结论显示：偏角馈入抛物面天线较中心馈入抛物面天线在抑制远旁瓣方面有优势,在做低仰角扫描时不会产生远旁瓣回波;但在高仰角时,也会产生远旁瓣回波。在多卜勒雷达的使用中,控制天线的转速有利于消除远旁瓣回波的影响。     

垂直指向多卜勒雷达测量大气垂直运动和雨滴谱等物理量的方法

在假定雨滴谱为指数分布的基础上,本文提出用垂直指向多卜勒雷达同时测量与雨和风有关的参量的新方法,即用多卜勒谱的倾斜率M_3(也就是谱的三阶中心距)和反射因子Z估计谱参量N_0和λ、大气垂直速度、由风切变和乱流引起的多卜勒谱宽、降雨含水量M和雨强R。这方法的主要优点在于乱流和风切变对M3的影响很小。作者在理论上和用数值模拟分析讨论了这方法的原理和误差。对一实例计算表明,M_3确实是与实测多卜勒谱有关的信号。最后对文中提出的由M3选择确切的λ值的技术作了初步讨论。     

单多卜勒雷达对台风的自动定位方法

利用单多卜勒雷达径向速度的ＰＰＩ资料,使用模式识别技术自动探测台风中心。结果表明本方法能较快较好地探测到台风中心,本产品可用来作为台风的预警系统。     

雨滴在静止大气中的平均多卜勒速度

为了克服用雷达反射因子Z求静止大气中平均多卜勒速度■关系式(即■_0—Z关系)随时间、地点、雨型而显示出的不稳定性,本文导出了雷达反射因子Z、雨强I和■_0之间的新关系式,即■_0=1.288(Z/I)0.2537。资料验证表明,这个新关系式是稳定的,而且精度比■_0—Z关系高。它还为使用常规测雨雷达和雨量计这种半遥感方法确定■_0提供了理论依据。     

由VVP探测技术提取风场信息的方法

本文讨论用最小二乘法处理VVP技术下测得的多卜勒速度来获取矢量风场信息量的方法。 从实际考虑,详细描述了近于真实的降水回波信号的模拟过程,着重分析了此模拟信号的估计结果及其误差,并就该方法探测的最佳范围进行探讨。最后简单分析非线性场的结果。     

单部多卜勒天气雷达探测低空风切变方法

利用单多卜勒天气雷达风场资料对一维径向、一维方位、二维复合风切变值进行了计算 ,并对机场附近飞机所受气流速度变化进行分析。所得结果旨在定量描述机场附近低空风切变区 ,检验对下击暴流、中气旋、阵风锋探测的结果 ,确定飞机起降潜在危险区。     

用Z和I确定雨滴在静止大气中的多卜勒速度标准差

本文提出了一种使用常规测雨雷达测定的雷达反射因子Z及雨量计测定的雨强I,在一定的假设条件下确定静止大气中降水粒子的多卜勒速度标准差σ_v的方案。用此方案对各类降水的雨滴谱进行了计算,并与在雷莱散射条件下按σ_v定义式计算的结果相比较,其平均相对误差在15—30%以内。     

转向台风的强度

引言除台风路径外,台风强度也是一个重要的预报参数。本文普查了大量西太平洋转向台风的强度变化,强度由飞机测到的最大风速来代表,所取时段为48到72小时。本文所用有关台风位置、大小、最低气压和最大风速的实况,系取自美军出版的1945—1968年由计算机得出的台风资料。在这24年的前期,最大风速报告的观测时间,一般规律性较差。不规律性虽在后几年也有,但可能因测风工具的改进,尤其是多卜勒雷达问世,因此     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.     

Revisiting the Concentration Observations and Source Apportionment of Atmospheric Ammonia

正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.     

Information for Authors

正AIMS AND SCOPE Atmospheric and Oceanic Science Letters (AOSL) publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography.     

Information for Authors

AIMS AND SCOPE
Atmospheric and Oceanic Science Letters （AOSL） publishes short research letters on all disciplines of the atmosphere sciences and physical oceanography. Contributions from all over the world are welcome.     

Information for Authors

AIMS AND SCOPE Atmospheric and Oceanic Science Letters （AOSL） pub- lishes short research letters on all disciplines of the atmos- phere sciences and physical oceanography. Contributions from all over the world are welcome.     

INFORMATION FOR AUTHORS

正Aims Scope Advances in Atmospheric Sciences(AAS)is an international journal on the dynamics,physics,and chemistry of the atmosphere and ocean with papers across the full range of the atmospheric sciences,co-published bimonthly by Science Press and Springer.The journal includes Articles,Note and Correspondence,and Letters.Contributions from all over the world are welcome.