一次霾天气条件下石家庄上空大气气溶胶数浓度的飞行探测与特征分析

利用2010年8月30日河北省石家庄一次霾天气条件下的气溶胶飞行探测资料,分析了石家庄地区上空658—6933 m高度范围内大气气溶胶粒子平均数浓度、平均直径的垂直分布特征和9个水平飞行高度上的谱分布特征。结果表明:轻度霾天气条件下的气溶胶平均数浓度为325个/cm3,平均直径为0.169μm。在约1000 m高度以下,气溶胶平均数浓度随高度的增加呈线性减少趋势。粒径也随高度增加而减小,由0.187μm减小至0.164μm。1000 m高度以上,气溶胶平均数浓度随高度减少趋势变缓,粒子平均直径在0.167~0.171μm范围内波动。9个不同高度上的谱分布都呈单峰型,随着高度增加,谱宽变小,峰值向小尺度方向移动。后向轨迹计算分析表明:污染气团的远距离输送可能是导致大气1500 m高度层气溶胶数浓度突增的原因。     

冬小麦农田裸温与气温差异分析及其应用

以矮秆代表作物冬小麦为研究对象,利用郑州农业气象试验站2010年10月15日—2011年6月2日农田小气候观测的各层裸温、气温、总辐射和覆盖度资料,采用对比差值、温度垂直梯度等方法统计分析,并对温度对比差值和总辐射曝辐量相关关系和温度的垂直梯度分布特征进行了研究,结果表明:25cm、150cm和300cm高度的日平均裸温和气温变化趋势基本一致,其对比差值呈由小变大趋势;各层裸温和气温的日分布符合温度日变化分布的一般规律,垂直梯度变化比较明显;各层对比差值呈单峰分布,峰值出现在正午12时左右;裸温和气温的对比差值与总辐射曝辐量呈线性相关。裸温与气温的垂直梯度变化有很好的一致性,可利用裸温不同层次间垂直梯度变化特征确定气温传感器合理的安装高度;根据麦田裸温垂直梯度变化特征,考虑到温度防辐射罩高度限制,矮秆作物田间小气候气温应在距离地表面25cm、50cm和150cm高度附近分别设置观测层次。     

Impact of the Vertical Velocity Field on Charging Processes and Charge Separation in a Simulated Thunderstorm

A three-dimensional(3D) charging-discharging cloud resolution model was used to investigate the impact of the vertical velocity field on the charging processes and the formation of charge structure in a strong thunderstorm. The distribution and evolution of ice particle content and charges on ice particles were analyzed in different vertical velocity fields. The results show that the ice particles in the vertical velocity range from 1 to 5 m s-1obtained the most charge through charging processes during the lifetime of the thunderstorm. The magnitude of the charges could reach 1014 n C. Before the beginning of lightning activity,the charges produced in updraft region 2(updraft speed 13 m s-1) and updraft region 1(updraft speed between 5 and 13 m s-1) were relatively significant. The magnitudes of charge reached 1013 n C, which clearly impacted upon the early lightning activity. The vertical velocity conditions in the quasi-steady region(updraft speed between –1 and 1 m s-1) were the most conducive for charge separation on ice particles on different scales. Accordingly, a net charge structure always appeared in the quasi-steady and adjacent regions. Based on the results, a conceptual model of ice particle charging, charge separation, and charge structure formation in the flow field was constructed. The model helps to explain observations of the"lightning hole" phenomenon.     

A diagnostic study of the asymmetric distribution of rainfall during the landfall of typhoon Haitang (2005)

The precipitation during landfall of typhoon Haitang (2005) showed asymmetric structures (left side/right side of the track). Analysis of Weather Research and Forecasting model simulation data showed that rainfall on the right side was more than 15 times stronger than on the left side. The causes were analyzed by focusing on comparing the water vapor flux, stability and upward motion between the two sides. The major results were as follows: (2) Relative humidity on both sides was over 80%, whereas the convergence of water vapor flux in the lower troposphere was about 10 times larger on the right side than on the left side. (5) Both sides featured conditional symmetric instability [MPV (moist potential vorticity) <0], but the right side was more unstable than the left side. (6) Strong (weak) upward motion occurred throughout the troposphere on the right (left) side. The Q vector diagnosis suggested that large-scale and mesoscale forcing accounted for the difference in vertical velocity. Orographic lift and surface friction forced the development of the asymmetric precipitation pattern. On the right side, strong upward motion from the forcing of different scale weather systems and topography caused a substantial release of unstable energy and the transportation of water vapor from the lower to the upper troposphere, which produced torrential rainfall. However, the above conditions on the left side were all much weaker, which led to weaker rainfall. This may have been the cause of the asymmetric distribution of rainfall during the landfall of typhoon Haitang.     

偏东气流诱发川西高原东侧两次对流暴雨过程的对比分析

利用区域自动站加密观测资料、NCEP/CFSR 0.5°×0.5°再分析资料以及0.01°×0.01°全球地形资料等,对2013年夏季发生在川西高原东侧两次对流暴雨天气过程中偏东气流的作用和特征进行了对比分析,重点研究两次过程中中低层偏东气流的活动特征、风场的垂直结构和温湿特征及其在对流暴雨中的作用等。结果表明：（1）7月3日过程高原东侧偏东风活动在850 hPa以下,持续时间约20 h,风速平均为2 m·s-1;8月6日过程偏东风活动在700 hPa以下,持续时间也能达到20 h,风速约为4 m·s-1;两次过程均是在天气尺度的西风槽东移与地形的共同作用下,诱生了高原东侧对流层中低层偏东气流,偏东气流形成时间比对流降水发生时间早约12 h。（2）两次过程偏东气流具有高相当位温属性,在其上方存在干冷空气活动,形成了有利的对流不稳定层结。相比较而言,后一次过程偏东气流出现的高度和风速明显增强后,与偏西风形成了更大的低层垂直风切变,暖湿能量局地集中特征更为显著,对于水汽和能量持续输送能力更强,因而引发的对流降水强度明显更大。（3）前一次过程盆地内起伏波动的偏东风与辐合中心及气旋性涡度中心配置关系较差,只是当偏东风受强迫抬升后,在地形附近激发出对流,并使降水主要位于地形附近;后一次过程盆地内平直的偏东风与辐合中心及涡度中心配置关系较好,尺度相当,因此激发出的对流强度和范围有明显增大,强降水沿地形向盆地西部发展。     

THE LOW-PRESSURE SYSTEM IN THE VERTICAL VELOCITY OMEGA ON THE SCALE OF SYSTEM SENSITIVITY

In this study, the relationship between scale and vertical velocity in a low-pressure system is explored using the wave characteristics of atmospheric disturbances and the structural characteristics of low-pressure systems. The ω differential equation, as determined by the transient geopotential height field Φ, is solved to obtain an analytical solution composed only of wavelength, horizontal speed, and atmospheric stability, i.e., the ω diagnostic equation of a low-pressure system. This equation also shows that vertical velocity in the low-pressure system is very sensitive to the horizontal scale, i.e., a smaller horizontal scale means a larger vertical velocity.     

Population variations in the grazing turbinid Lunella smaragda (Mollusca: Gastropoda)

The grazing turbinid gastropod Lunella smaragda was sampled regularly over 3.5 y from precise sites of different microtopography and height on the platform shore at Goat Island Beach near Leigh, Northland, New Zealand. Growth is linear for over 3 y, and the year‐classes distinct. The position of the different size‐classes is related to both the shelter afforded by the microtopography, and to the height on the shore. The populations in the mid‐eulittoral turf flats, low eulittoral bare rock areas, and the sublittoral fringe are distinct, and there is a general movement down the shore with age and size. Wave action apparently dislodges the animals from higher areas when they grow to a critical size and transports them to sites lower on the shore, where wave disturbance is less. Field experiments with marked animals and laboratory studies with a wave tank confirm that the wave‐effected distribution is size related. However measurements showed that the ratio of foot attachment area to the shell area presented to the wave does not vary with animal size. The possible benefits of wave dislodgment and wave‐effected distribution are considered.     

Heavy metals in some New Zealand commercial sea fishes

To establish a base line against which future pollution may be measured, eight common commercial species of New Zealand sea fish were analysed for cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc. One sample of edible muscle tissue was analysed for each of 70 samples of each species. The internal organs of up to five specimens of each species were also analysed. The fish studied were: kahawai, Arripis trutta, trevally, Caranx lutescens, tarakihi, Cheilodactylis macropterus, snapper, Chrysophrys auratus, moki, Latridopsis ciliaris, hapuku, Polyprion oxygeneios, kingfish, Seriola grandis and gurnard, Trigla kumu.

Although, none of the edible parts of the fish appeared to have trace element levels likely to be a public health problem (cadmium 0.002–0.02 ppm, chromium 0.01–0.04 ppm, copper 0.04–0.95 ppm, iron 0.9–13.5 ppm, lead ‘ 0.14–0.95 ppm, manganese 0.04–2.00 ppm, nickel 0.01–0.08 ppm, zinc 2.0–36.0 ppm), some of the organs (particularly the liver) had relatively high concentrations of elements such as cadmium (up to 54 ppm). Only if some industry were to seek to exploit internal organs of fish for human consumption would such levels become important. There was some evidence for a relationship between trace element concentrations and fish size for copper in kingfish and snapper, iron in hapuku, manganese in gurnard, and for zinc in kingfish and tarakihi. Some element pairs such as copper and zinc, iron and manganese, appeared to have concentrations which were mutually related. It was assumed that the elemental concentrations reported represent natural levels and are not the result of significant man‐made pollution because there are no major industries or large urban centres adjacent to the fishing grounds.     

Introduction,preliminary handling,and diseases of grass carp in New Zealand

Fry of grass carp, Ctenopharyngodon idella (Val.), were air‐freighted from Hong Kong to New Zealand in October 1971. The fish were at first kept in tanks with a recirculating water supply, where they soon showed symptoms of parasitic infestation and suffered heavy mortality.

Attempts were made to remove parasites with chemotherapeutic treatment. Tripartiella sp., Dactylogyrus ctenopharyngodonis, and Gyrodactylus clenopharyngodontis were eliminated by prolonged bathing of the infected fish with quinine. Chemical treatment failed to eliminate Ichthyophthirius mullifiliis from the body surface and the gills, but the rate of spontaneous recovery of the fish from this disease was accelerated by keeping them in clean, running water. Experiments to remove the cestode Bothriocephalus gowkongensis from the intestine of the fish with tetravalent tin compounds and to control the intermediate host (Cyclops) in the water resulted in the eradiction of the cestode.

When parasitic infestations had been brought under control the fish were transferred to outdoor ponds, where they began to feed on aquatic and terrestrial vegetation and rapidly increased in size.     

Preliminary model of nitrogen loads from southern bluefin tuna aquaculture

Farming of wild tuna in coastal areas is a relatively new aquaculture industry and little is known about the magnitude of nutrient discharges to the environment. In this work we present a preliminary model of nitrogen loads from southern bluefin tuna (Thunnus maccoyii) aquaculture in lower Spencer Gulf, South Australia. The model was developed based on feed inputs, estimates of fish metabolism and environmental data. Two pens were monitored over a full grow-out season to determine nitrogen sedimentation fluxes, remineralization at the sediment-water interface and accumulation in the sediments. The model suggests that the high metabolic rates of tuna lead to low retention of nitrogen in fish tissues (7-12% of feed inputs) and high environmental losses (260-502kg Ntonne(-1) growth). Considering Australian annual production of 4380tonnes over initial stocked biomass, total loads can reach 1137tonnes N per year, 86-92% lost as dissolved wastes. The nature of wastes suggests low localized impacts at current stocking densities and holding periods.