ON THE STUDY OF THE RELATIONSHIPS BETWEEN GUANGZHOU ATMOSPHERIC ENVIRONMENT FACTORS AND THE SARS EPIDEMIC

Based on SARS epidemic data and the corresponding atmospheric data, we used the timescale-partitioning technique, spectrum analysis and correlation analysis to investigate the impacts of the atmospheric environmental factors on the SARS epidemic. Results showed that there were close relations between environmental factors and SARS: The daily probable cases of SARS varied in 3-5 day cycles, much the same as the atmospheric elements did. The variations of the epidemics correlated remarkably with atmospheric elements. So conclusions can be drawn that weather changes have influences on the variations of daily SARS cases. In addition, statistical results showed that cold air activities aggravated the SARS epidemic.

ANALYSIS OF MID-SUMMER HIGH TEMPERATURE FREQUENCY ANOMALY IN GUANGZHOU

Using EOF, correlation analysis, the climatic characteristics are analyzed of the yearly high temperature frequency (HTF) in Guangzhou from 1951-2004, and the relationship between the mid-summer (July and August) HTF anomaly and the synchronous 500hPa heights of the region(65 - 150°E, 10 - 70°N) is also discussed. The results show that: (1) the average of HTF is 8.7 days per year in the recent 54 years in Guangzhou; high temperature occurs from May to September, and July and August have the highest frequency of occurrence; (2) there are distinct interannual and interdecadal changes in Guangzhou HTF, with an obvious increase since the 1980s; (3) the anomalous increase of mid-summer HTF in Guangzhou since the 1980s has a close relationship with the weakened westerlies in Northwest China, Mongolia, Lake Baikal and their vicinity and the intensified subtropical high in the mid-low latitude areas.

An Overview of Research and Forecasting on Rainfall Associated with Landfalling Tropical Cyclones

The ability to forecast heavy rainfall associated with landfalling tropical cyclones (LTCs) can be improved with a better understanding of the mechanism of rainfall rates and distributions of LTCs. Research in the area of LTCs has shown that associated heavy rainfall is related closely to mechanisms such as moisture transport, extratropical transition (ET), interaction with monsoon surge, land surface processes or topographic effects, mesoscale convective system activities within the LTC, and boundary layer energy transfer etc.. LTCs interacting with environmental weather systems, especially the westerly trough and mei-yu front, could change the rainfall rate and distribution associated with these mid-latitude weather systems. Recently improved technologies have contributed to advancements within the areas of quantitative precipitation estimation (QPE) and quantitative precipitation forecasting (QPF). More specifically, progress has been due primarily to remote sensing observations and mesoscale numerical models which incorporate advanced assimilation techniques. Such progress may provide the tools necessary to improve rainfall forecasting techniques associated with LTCs in the future.

Turbulent Variance Characteristics of Temperature and Humidity over a Non-uniform Land Surface for an Agricultural Ecosystem in China

这篇论文在中国在一个混合农业区上为流动评价描述变化方法的申请。埃迪协变性和流动变化大小从 6 月 7 日在中国的中央平原在不一致的陆地表面上在近表面的层被进行到 2002 年 7 月 20 日。在这个时期期间，吝啬的华盖高度是大约 0.50 m。Thestudy 地点由草(10% 区域) 组成了，豆子(15%) ，玉米(15%) 和米饭(60%) 。在不稳定的条件，温度的标准差和水汽密度下面(由适当可伸缩的参数使正常化) ，由一台单个仪器观察了，跟随了 Monin-Obukhovsimilarity 理论。为热(C_T ) 和水汽(C_q ) 的类似常数分别地是 1.09 和 1.49。与用旋涡协变性技术的直接测量比较，平均，流动变化方法低估了可感热在21%的流动和在24%的潜伏的热流动，它可以被归因于事实观察细微偏差(20%或30%至多)类似，“常数”可能在从thegenerally有效的关系的一台单个仪器的变化的期望的范围以内。

CONNECTION OF THE SOUTH CHINA SEA SUMMER MONSOON TO MARITIME CONTINENT CONVECTION AND ENSO

The relationship between the intensity of the South China Sea summer monsoon (SCSSM) and the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak SCSSM are investigated using the NCEP/NCAR reanalysis data, Extended Reconstructed Sea Surface Temperature (ERSST) data and Climate Prediction Center Merged Analysis of Precipitation (CMAP) data. The SCSSM is significantly positively correlated with the Nino3.4 index in the succeeding northern autumn and winter. In the strong minus weak SCSSM composite, a positive East Asia-Pacific teleconnection (EAP) pattern and a negative Europe-Asian-Pacific teleconnection (EUP) pattern appear in the 500 hPa height difference field; low-level cross-equatorial flows are strengthened over the Maritime Continent (MC) region; positive (negative) precipitation anomalies occur in the South China Sea and western north Pacific (MC). A possible mechanism through which SCSSM affects ENSO is proposed. A strong (weak) SCSSM strengthens (weakens) cross-equatorial flows over the MC. The anomalous cross-equatorial flows cool (warm) the SST around the MC through enhanced (reduced) surface latent heat fluxes. The cooling (warming) further leads to suppressed (enhanced) convection over the MC, and causes the anomalous westerly (easterly) in the equatorial western Pacific, which favors the onset of El Nio (La Nia) through modulating the positive air-sea feedback process.

SINGULAR SPECTRUM ANALYSIS FOR TROPICAL CYCLONE LANDING IN GUANGDONG

Using the method of Singular Spectrum Analysis (SSA), the evolution regularity of tropical cyclo- nes landing in Guangdong are analyzed. The main periods of yearly topical cyclones landing in Guangdong are found at 8 and quasi-3 years, and in the west of Pearl River Mouth are 12 and quasi-2 years to the west of Pearl River Mouth. The northwest Pacific that topical cyclones are generated is divided into 8 areas, and the SeaSur- face Temperature (SST) in each area is analyzed using SSA. The main periods of NINO-west are 8 and 3 years, and those of the warm pool are 12 and 2 years, respectively. This may be the physical reason for the generation tropical cyclones landing in Guangdong. By combining the Maximum Entropy Method (MEM) with SSA (SSA- MEM), the yearly variation trend of tropical cyclones landing in Guangdong and the Pearl River Mouth are force- ast, and the results are good. The method can be used in operational short-range climate forecast.

VARIATION OF PRECIPITATION DURING WINTER AS A CAUSE OF SUSTAINED DROUGHT IN GUANGDONG DURING THE PAST 50 YEARS

The variation characteristics of precipitation during the winter(between October and the following March,to be referred to as just"the winter"hereafter) in Guangdong province during the past 50 years(from 1957 to 2006) and the relationship with Pacific SST are studied using the methods of Empirical Orthogonal Function(EOF) analysis,wavelet analysis,and correlation analysis.The results show that The Guangdong precipitation during the winter exhibits quasi-periodic significant oscillations of 40 years and 2 years;rainfall is less from the end of the 1950s to the start of the 1970s and from the end of the 1990s to the present than from the mid 1970s to the mid 1990s.The frequency of sustained drought is more than sustained flooding during the winter.The Guangdong precipitation during this time period is in significantly positive correlation to the equatorial central and eastern Pacific SST,but in a significantly negative correlation with the western and northern Pacific SST east of the Philippine Sea.61.5% of the sustained drought occurred in the phase of negative anomalies of the Nio3.4 index and 38.5% in the phase of positive ones.A composite analysis of atmospheric circulation is performed for the positive and negative phases of the Nio3.4 region associated with the sustained drought.The results showed that a weak polar vortex,a strong trough in Europe and a ridge near Balkhash Lake,active cold air and consistent northerly wind anomalies controlling Guangdong at low levels,an inactive westerly low disturbance in the low-mid latitude of the Asian continent,and a weak southern branch westerly trough,are all mutual causes for the sustained drought.

CONTRAST ANALYSIS OF APRIL TYPHOONS LEO AND NEOGURI

The conventional observations data,NCAR/NCEP-2 reanalysis data,and NOAA outgoing longwave radiation data are used to investigate different characteristics of Leo and Neoguri,two April typhoons that ever made landfall on the continent of China over the past 60 years.The results showed that both Leo and Neoguri occurred during the La Nina events.Strong convective activity,weak vertical wind shear and upper-level divergence were in favor of the formation of these April typhoons.Leo originated from a monsoon depression and Neoguri evolved from an easterly wave.The meandering moving track of Leo attributed to strong northeast monsoon and a weak and changeable subtropical high;the steady moving track of Neoguri was governed by a strong and stable subtropical high.Leo and Neoguri had similar terrain conditions and intensities during landfall but were different in precipitation as water vapor transport and duration of kinetic uplifting resulted in apparent discrepancies between them.

THE RELATIONSHIP BETWEEN SOUTH CHINA SEA SOUTHWEST MONSOON ANOMALIES AND IMPORTANT WEATHER IN GUANGDONG PROVINCE DURING THE RAINING SEASONS

The activity of South China Sea southwest monsoon (SCSSM) has direct impacts on the anomalies of important weather in Guangdong province during the raining seasons. So it is necessary to explore thoroughly the activity pattern of SCSSM and its relationship with important weather anomalies in the province. In this paper, the methods of composite analysis and correlation statistics are used to study the relationship between the onset date and intensity of SCSSM and the important weather, such as precipitation trends in Guangdong province during the annually first and second raining seasons, the timing of the annually first and last typhoon and the number of typhoons landing in Guangdong province. The results show that the rainfall is less than normal during the first raining season, but more than normal during the second one and there are more tropical cyclones landing in Guangdong province in the years of early SCSSM onset. The rainfall is more than normal during the second raining season and there are more tropical cyclones landing in Guangdong province in the years of strong SCSSM. The relationship between the SST of April - June, July - September and previous winter (December - February) and 500 hPa geopotential height and the onset date and intensity of SCSSM is analyzed. Some mechanisms between the onset dates and intensity of SCSSM and the important weather anomalies in Guangdong province are preliminarily explored. The results can be used for reference in short-term climate forecast.

THE VARIABILITY CHARACTERISTICS AND PREDICTION OF GUANGDONG POWER LOAD DURING 2002 – 2004

The variability characteristics of Guangdong daily power load from 2002 to 2004 and its connection to meteorological variables are analyzed with wavelet analysis and correlation analysis. Prediction equations are established using optimization subset regression. The results show that a linear increasing trend is very significant and seasonal change is obvious. The power load exhibits significant quasi-weekly (5 – 7 days) oscillation, quasi-by-weekly (10 – 20 days) oscillation and intraseasonal (30 – 60 days) oscillation. These oscillations are caused by atmospheric low frequency oscillation and public holidays. The variation of Guangdong daily power load is obviously in decrease on Sundays, shaping like a funnel during Chinese New Year in particular. The minimum is found at the first and second day and the power load gradually increases to normal level after the third day during the long vacation of Labor Day and National Day. Guangdong power load is the most sensitive to temperature, which is the main affecting factor, as in other areas in China. The power load also has relationship with other meteorological elements to some extent during different seasons. The maximum of power load in summer, minimum during Chinese New Year and variation during Labor Day and National Day are well fitted and predicted using the equation established by optimization subset regression and accounting for the effect of workdays and holidays.

A STATISTICAL MODEL FOR PREDICTION OF INTENSITY AND FREQUENCY OF TROPICAL CYCLONES MAKING LANDFALL ON CHINA

Based on NCEP/NCAR reanalysis data and Yearbook of China landfalling tropical cyclones(hereafter CLTC) from 1949 to 2008,correlation between CLTC frequency/intensity and 500 hPa height field and sea surface temperature(SST) fields are investigated and employed for TC statistical prediction.A prediction model for yearly and monthly intensity and frequency of CLTC is established with binomial curve fitting by choosing the gridpoints with high correlation coefficients as composite factors.Good performance of the model in experiments shows that the model could be used in routine forecast.

COMPARISONS BETWEEN DOPPLER AND SIMULATED FEATURES OF A SUPERCELL

Firstly, typical features of a supercell, which occurred in Guangzhou on August 11, 2004, are discussed by using the new generation weather radar data. V-notch, finger-echo, weak echo region, overhang and echo-wall are observed from reflectivity products. A vertical cross section of the radial velocity is made along the direction of the low-level inflow and across the maximum reflectivity core, which displays a part of strong updraft and downdraft. Secondly, a 3-D convective storm model is used to simulate the supercell. The maximum reflectivity and the core thickness of the simulated radar echo are 75 dBz and 14km, respectively. These values are more than the counterparts that are detected by radar. The reason is that attenuation is not calculated in the model. The wind field structure is also given when the storm is the strongest. Divergence, caused by thunderstorm outflow, is in the low level. In the middle and high level, convergence is dominant, but the plume is not simulated at the top. Finally, the evolution of the simulated vertical motion is documented. The interaction between the environmental wind and the updraft, which is formed by the convergence on the ground at the beginning, makes the storm stronger. Then, downdraft occurs and grows. When it becomes dominant, the supercell collapses.

SPATIAL AND TEMPORAL VARIATIONS OF EVAPORATION OVER SOUTH CHINA IN AUTUMN

The spatial and temporal variations of the instrument-based evaporation and actual evaporation in autumn during a 45-year period from 1960 to 2004 are studied using the observation data from 66 stations over South China. The results reveal that there are two main anomalous centers of the instrument-based evaporation in autumn in the central and northwestern parts of South China respectively. The instrument-based evaporation over the central part of South China in autumn experiences not only a decreasing trend but also a main interdecadal variation. The solar radiation is best correlated with the instrument-based evaporation among all affecting factors. For the actual evaporation, two main anomalous centers are located at the central and western parts of the South China respectively. The actual evaporation over the two regions illustrates an interannual variation. Among the affecting factors, precipitation is the most remarkable. The actual evaporation is usually 40 percent of the instrument-based one, and the overall rate has a slightly increasing trend from the southern part to the northern part of the South China in autumn.

Hazard Analysis of Severe Convective Weather in Guangdong Province, China

In the present study,a hazard model of severe convective weather was constructed on the basis of meteorological observational data obtained in Guangdong Province between 2003 and 2015.In the analysis,quality control was first conducted on the severe convective weather data,and the kriging method was then used to interpolate each hazard-formative factor.The weights of which were determined by applying the coefficient of variation method.The results were used to establish the hazard-formative factor model of severe convective weather.The cities showing the greatest hazards for severe convective weather in Guangdong Province include Yangjiang,Dongguan,Foshan,Huizhou,Jiangmen,and Qingyuan.

The coral grayness in northern South China Sea and its description of interdecadal variation of precipitation in south China

The interdecadal variation of coral grayness in northern South China Sea (SCS) is studied using the annual mean coral grayness in northern SCS from 1789 to 1992 and annual precipitation at Guangzhou from 1908 to 1992 by Singular Spectrum Analysis (SSA), correlation analysis, Mann-Kendall’s abrupt change analysis and composite analysis. The interdecadal variation of south China precipitation as reflected by the series of Guangzhou precipitation rebuilt with the coral grayness is discussed. The results show that the variation of coral grayness in SCS has significant terms of tendency, much-weighted interdecadal variation and weak interannual variation. There was a century-scale abrupt change of coral grayness at the end of the 1880s that changed from positive anomalies to negative anomalies. The global field of SST difference corresponding to the point of abrupt change was negative anomalies over the SCS and neighboring northern Indian Ocean, most of central and western Pacific Ocean and coastal areas of the northern Atlantic Ocean. The large-scale distribution of SST anomalies is concomitant with the century-scale abrupt change of coral grayness in SCS. Negative correlation exists between the coralgrayness in SCS and precipitation in Guangzhou on the interdecadal scale and the interdecadal precipitation in Guangzhou as reflected by the interdecadaldata of SCS coral grayness shows that the interdecadal variation of south China precipitation changes significantly from phase to phase. The current study aims at contributing in the effort of identifying alternative indexes for climate change in south China on the interdecadal scale and beyond.

THE INTERANNUAL OSCILLATION OF RAINFALL OVER CHINA AND ITS RELATION TO THE INTERANNUAL OSCILLATION OF THE AIR-SEA SYSTEM

The quasi-biennial oscillation (QBO) and 3.5 years quasi-periodic oscillation (named TO hereafter) areexhibited in most of 48 weather stations of China by applying power spectrum analysis to the monthly rainfalldata for the period from Jan. 1933 to Dec. 1987. In order to reveal the features of QBO and TO components, another rainfall data set in 160 stations overChina for the period from Jan. 1951 to Dec. 1987 was analysed by means of a new method named complexempirical orthogonal function (CEOF). The results show that both QBO and TO modes exhibit two propaga-tion ways: one originates in Northeast China, extends southward, passes through North China and reaches theeastern part of Northwest China and the northern part of Southwest China; the other appears over Guangdongand Fujian, then moves northward and westward respectively to the Huanghe-Huaihe Basin and Southwest China.These two paths of oscillation meet over North China and the area between the Changjiang River and the HuangheRiver. A significant correlation exists between the interannual oscillation of the rainfall over China and that of thesea surface temperature (SST) at the equator. Although the correlation between the rainfall over China andthe SST over the equatorial eastern Pacific is rather weak, the correlation between their oscillation component ispronounced.

Topographic Effect on the Energetics of Geostrophic Adjustment

In this work, the impact of topography on the geostrophic adjustment process is discussed with a simple two-layer shallow water model, in which the lower-layer fluid is initially stationary while the upper-layer is perturbed by the impulsive injection of momentum. During the geostrophic adjustment process of this ideal model, the initial kinetic energy is released and a fraction of it is converted into potential energy of the final geostrophically adjusted state. Thus, after the geostrophic adjustment, the kinetic energy of the system is reduced while the potential energy is enhanced. As the topographic effect is considered, it is found that the decrease of the kinetic energy (ΔRE) and the increase of the potential energy (ΔPE) of the system are weakened as compared to the case that the lower boundary is flat. Furthermore, the topographic effect on ΔPE is less pronounced than that on ΔKE, which implicates that the topography tends to inhibit the energy dispersion of the inertio-gravity wave. The numerical simulation of the geostrophic adjustment process shows that, due to the impact of topography, the convergence and divergence in the low layer are reduced and the undulation of the interface between the lower-layer and upper-layer is weakened. This means that the amplitude of the inertio-gravity wave is decreased, and thus, the energy radiated by the inertio-gravity wave is lessened.

Automatic Identification of Storm Cells Using Doppler Radars

三暴风雨为 Doppler 雷达的自动鉴定算法被讨论。WSR-88D 造 7.0 (B7SI ) 由多重规定阀值测试客观回响的紧张和连续性到造 3D 暴风雨，并且什么时候下暴雨，正在合并切开，或仔细聚类，察觉错误变得更大。B9SI 算法是 Build 的部分 WSR-88D 系统的 9.0 雷达产品生成器。它使用反射率的多重阀值，最新设计房间原子核抽取并且靠近暴风雨的处理的技术，因此能够识别多细胞的暴风雨里的嵌入的房间。在长距离的强壮的区域部件被另存为 2D 暴风雨。然而， B9SI 不能在暴风雨的传送对流力量上给信息，因为反射率的质地和坡度是不计算的，光线的速度数据没被使用。克服这限制， CSI (对流暴风雨鉴定) 算法在这篇论文被设计。由使用模糊逻辑技术，并且在 B9SI 的七反射率阀值的层次被降低的条件下面， CSI 处理雷达库数据和 B9SI 的输出获得暴风雨的传送对流索引。最后， CSI 与在 2004 年 8 月 11 日发生在广州的一个超级房间的盒子被验证。计算并且传送对流的二上升索引的分析结果表演与合并生长和超级房间的强壮的会聚的生长匹配很好，并且当超级房间最强壮，然后减少时，索引是 0.744。相应地，最大的反射率的高度，也由雷达检测了减少，并且大雨也发生在一个大规模区域。

Analysis on Anomalous Precipitation in Southern China During Winter Monsoons

The winters of 1997/1998 and 1998/1999,corresponding to El Ni(?)o and La Ni(?)a episodes,respectively, were two typical rain-abundant and-scarce seasons for the southern China.In order to understand the cause of the anomalous precipitation during the two winters,a comparative analysis technique has been employed to investigate the differences in general circulation and moisture transportation between the two seasons. The results show that the abundant rainfall during the winter of 1997/1998 was associated with the ENSO warm episode event,eastward shifted weak westerly trough/ridge,weakened East Asian winter monsoon (EAWM),strengthened subtropical high,and presented two anti-cyclonic circulations over Hokkaido and the Philippine Sea,respectively,as well as one cyclonic circulation over the Yangtze River Basin in the anomalous wind fields of the lower troposphere.During the rain-scarce winter,however,the patterns of equatorial sea surface temperature anomalies and the circulation systems both in upper and lower levels were nearly the opposite of those during the rain-abundant winter.It has also been discovered that the water vapor over southern China during the winters came mainly from the southwesterly flow ahead of troughs in the southern branch of westerlies and the turning flow over the South China Sea-Indo-China Peninsula area;and the moisture transportation channels varied significantly with regard to height.The intensified flow in the southern branch of westerlies and the anti-cyclonic circulation anomaly over the Philippine Sea during the winter of 1997/1998 were favorable for moisture transportation to China's Mainland,however the two moisture transportation streams were dramatically weakened during the winter of 1998/1999 due to weak westerly flow and the dominance of a cold high system in the lower level over the southeast coast of China.Such a significant inter-annual change of moisture transportation is a key factor resulting in the obvious difference in precipitation between the two winters.