Seasonal variation of global stratosphere-troposphere mass exchange

By Wei formula in pressure coordinate, the stratosphere-troposphere mass exchange (STME) is diagnosed globally for 44 years from 1958 to 2001 using the European Center for Medium-Range Weather Forecasts (ECMWF) reanalysis datasets. Regions of mass flux into the stratosphere are found over Indonesia, bay of Bangladesh and the mid-west coast of South Africa. Compensating mass outflow from the stratosphere appears mainly over mid-latitudes near large-scale troughs. Upward and downward transport of mass at the middle and high latitudes accompany with each other. Mass flux into troposphere is stronger in autumn and winter than in spring and summer. Strong downward mass flux into the troposphere occurs in eastern Asia the whole year with nearly stable sites. Although the area of eastern Asia accounts for only 5.6% of that of the northern hemisphere (NH), its net mass exchange reaches 15.83% of that of the NH, which means that research on STME of eastern Asia is greatly important to that of the NH and even the global areas. Air across the tropopause enters more from stratosphere to troposphere than that from troposphere to stratosphere, which is possibly related with systematic bias of the assimilated datasets and with persistent rise of the tropopause height. Contributions of the mass exchange and the mass flux exchange in the NH and southern hemisphere (SH) on their latitudes increase from equator to pole, with larger contributions in the NH. Mass exchange and mass flux exchange per areas at high latitudes are larger than that at low latitudes, which means greater mass exchange efficiency at high latitudes.     

An estimation of ozone flux in a stratosphere-troposphere exchange event

A new method based on mass fluxes and observed ozone profiles was developed to estimate crosstropopause ozone flux. Using this method, we estimated the cross-tropopause ozone flux in a stratospheric-tropospheric exchange event that occurred over East Asia in March 2001.The result revealed that the ozone flux across the tropopause in this event was an order of magnitude higher than the global and hemispheric average. Compared to the traditional method using a linear relationship between ozone mixing ratio and potential vorticity near the tropopause, the cross-tropopause ozone flux evaluated with ozonesonde data was somewhat higher, although the orders of the two values were the same.     

东海PN断面障碍层和水团的季节变化特征及其可能联系

本文利用PN断面的高分辨率海水温-盐-深剖面测量仪(CTD)温度、盐度和密度资料进行分析,发现PN断面处的水团有明显的陆架水和黑潮水的交汇特征,且随着季节的变化PN断面处的水团特征也发生明显的变化.通过观测资料还确定了PN断面处障碍层是常年存在的而且具有显著的季节变化.采用曲线族拟合的水团分析方法,根据不同季节PN断面上陆架水和黑潮水的混合特征,证明了水团混合在障碍层形成及季节变化中的重要作用,发现障碍层的季节变化与陆架水团和黑潮水团混合的季节变化密切相关.夏季,陆架水团向外海延伸,浮置于黑潮水之上,此时障碍层深度最浅,障碍层厚度最大;秋季,黑潮水离岸最近,将黑潮水与陆架水的交汇处向西压迫至陆架内,此时几乎不存在障碍层,零星存在的障碍层深度较深,厚度是一年当中最薄的;冬季,由于黑潮水的核心相对于秋季向深海移动,使得陆架混合水也相应地向外海拓展,而且此时陆架水与黑潮水的交汇处不只在混合层内而是影响到跃层,此季节障碍层是一年当中深度最深,厚度最厚的;春季,黑潮水的核心以及两种水团的交汇处相对于冬季的位置更向深海移动,所以此时PN断面上的障碍层深度和厚度相对于冬季变化不大,只是位置东移.海面风场和净热通量场通过改变...     

大气对流层顶热量收支变化的时空结构研究

 利用1948~2006年NCEP/NCAR的温度场、风场和对流层顶气压场的逐日资料,对全球对流层顶热量收支及其方差进行了计算.通过对计算结果的分析发现:①南北两半球对流层顶断裂区附近以及青藏高原是对流层顶热量收支变化的显著区域,南半球纬向平均加热率随纬度的波动比北半球剧烈;②赤道附近对流层顶的热量收支处于相对的准平衡态,而加热率突变性最强的区域位于海陆交界的洋面上空;③全球对流层顶的平均热量收支是处于大气冷却为主的热力学状态结构中,而且平均加热强度的主要年代际演变呈现出整体降低的趋势,年际变化则具有显著的QBO现象;④南北半球对流层顶正负加热率存在着随季节变化的空间波列结构,夏季加热率的经向梯度较弱,而冬季经向梯度增强并具有多样性;⑤对流层顶断裂带所在区域为加热率方差常年显著的带状区域,方差的高值带随着季节的转换存在着南北向的移动和东西向的伸缩现象,冬季是对流层顶空间热量收支变化最活跃的季节.     

Seasonal variation of snow microbial community structure in the East Rongbuk glacier, Mt. Everest

Mt. Everest, the zenith of the world, plays an impor- tant role in the global climate change. During the lastdecade, some studies on glacier and snow have been undertaken in this region. The climate and environment changes in the past hundred years have b…     

Seasonal variation of the temperature profile and its characteristics within urban roughness sublayer

By using conventional micro-meteorological observation data of Beijing Yuetan Park Tower (180 m), the temperature profile of urban boundary layer (UBL), its characteristics and seasonal variation are analyzed. The main results are as follows: (1) In winter, the interdiurnal surface air temperature varia- tion at the surface is not synchronized with that of the upper levels, other than in summer and other seasons, which illuminates the impacts of Beijing’s geographical location, sky view factor and stably st...     

大气对流层顶的臭氧时空分布变化

 利用1958~2001年的臭氧垂直分布和NCEP资料,计算出全球对流层顶的气候场,并对其空间分布、季节、年际和年代际演变进行了分析.结果表明:①对流层顶臭氧质量比呈纬向分布的特征明显,南北半球中纬度和南极为高值区,赤道和北极为低值区,且与对流层顶高度和温度场有对应关系;②从400~70 hPa的温度和臭氧质量比垂直经向剖面中,显现出对流层顶的上层和下层由于具有不同的物理和化学过程导致垂直分布存在差异;③对流层顶臭氧质量比纬向距平场的年代际变率具有不同位相的时空演变尺度,南半球的时空差异比北半球大,南极最不稳定,低纬和赤道地区幅度变化较小,但时间尺度较大;④极地各季节对流层顶的臭氧分布和高度场特征相似,低纬则与温度场分布较一致;⑤对流层顶断裂带中臭氧质量比最大值出现在春季,秋季为最小值,其对应的纬度存在明显的季节空间经向波动,夏季达到最高纬度,冬季到达最低纬度;⑥对流层顶臭氧质量比纬向距平的季节变率表现出准半年变化趋势,且两半球变化趋势相反.     

Seasonal variation of surface currents in the southwestern Taiwan Strait observed with HF radar

Long-term measurements from a pair of High-Frequency radar systems deployed near the coast of southern Fujian Province showed that surface currents in the southwestern Taiwan Strait were composed mainly of the monsoon-driven, seasonal fluctuation of longshore current and a persistent northeastward background flow with speeds around 10 cm/s. Measurements from bottom-moored ADCPs further indicated that below the surface Ekman layer longshore currents also directed to the north all year round.     

Seasonal vertical crustal motions in China detected by GPS

By analyzing daily continuous data of Chinese Global Positioning System (GPS) fiducial network with 25 sites from 1999 to 2001, seasonal altitude variations with amplitude of 3-10 mm are detected. Most part of the variations can be explained by the seasonal vertical crustal movements caused by atmospheric pressure variation and mass loading redistribution of non-tidal ocean loading, snow, and soil moisture. Nevertheless, there exists a systematic discrepancy between GPS deduced result and the counterpart predicted by combining various geophysical sources. Much longer time series of GPS site coordinates and further studies are still needed to give out a reasonable interpretation for this discrepancy.     

全球对流层顶气压场和温度场的时空演变结构特征

 利用1948~2004年共57年的对流层顶气压场和温度场资料,对全球对流层顶平均温压场的空间分布结构、年际和年代际变化以及季节变化进行了分析.结果表明:①热带对流层顶和极地对流层顶的平均气压场的空间位置和热状况大致吻合,并存在空间波动性,两半球对流层顶的温压场具有显著的非对称性;②对流层顶的纬向气压与温度距平场都具有不同尺度的年际和年代际变化,两极地区对流层顶的温压场最不稳定,两半球中纬度地区的时间演变尺度存在明显差异.对流层顶断裂带及其对应温度的时空波动存在反位相关系,20世纪70年代末温度出现突变现象,此时对流层顶断裂带迅速向南部空间移动;③不同季节对流层顶的温压场都将进行空间结构的调整,两者之间存在着季节变化的协调性,但北半球较南半球的演变过程复杂;④对流层顶温压场纬向距平的季节变率可划分为5个位相不同的时空波动区域,构成了气压场和温度场的经向型相关结构.北极地区气压场变化有超前于温度场变化的趋势,对流层顶断裂带的温度季节变化存在着双峰波动结构.冬半年断裂区的地理位置较夏半年稳定,气压场和温度场的最大季节变程均发生在南极.     

The seasonal cycle of interhemispheric oscillations in mass field of the global atmosphere

Using the daily and monthly data of surface air pressure, meridional wind, radiation and water vapor from NCEP/NCAR reanalysis for the period of 1979―2006, we have examined the seasonal variations of the interhemispheric oscillations (IHO) in mass field of the global atmosphere. Our results have demonstrated that IHO as observed in surface air pressure field shows the distinct seasonal cycle. This seasonal cycle has an interhemispheric seesaw structure with comparable annual ranges of surface air pressure in the Southern and Northern Hemispheres. Mass of water vapor changes out-of-phase between the Southern and Northern Hemispheres, showing clearly a seasonal cycle with its annual range almost equivalent to annual range of the IHO seasonal cycle. Amazingly, the cross-equatorial flow is found to be induced by annual changes in water vapor mass as a response of the atmosphere to seasonal cycle of forcing from hemispheric net surface short- and long-wave radiations. The IHO seasonality exhibits its larger variations in magnitude in mid-latitudes other than in other regions of the globe. Additionally, our results also show that the global air mass is redistributed seasonally not only between the Northern and Southern Hemispheres but also between land and sea. This land-sea air mass redis- tribution induces a zonal pattern of surface air pressure in the Northern Hemisphere but the meridional pattern in the Southern Hemisphere.     

一种适用于质量交换网络优化的节点非结构模型

质量交换网络（MEN）作为过程集成系统的新兴分支方向，具有提高资源利用效率和降低环境污染的双重效益。目前典型的超结构模型在MEN优化中已经取得了很好的应用，但超结构固定排列方式限制了模型中换热器匹配的灵活性和求解域的扩大。基于此，提出了一种新的有分流节点非结构模型，以节点的形式量化传质单元的匹配方式，实现传质单元在流股上的自由匹配，从而增强了单元匹配的灵活性。同时考虑到实际工程中有分流情况的出现，以分组数和分支数表示传质单元的有分流形式，进一步扩大了模型的求解范围。最后，通过2个实际MEN算例分析计算，验证了有分流节点非结构模型的有效性。     

天女木兰多酚类物质的季节变化规律

通过对不同月份天女木兰叶中多酚类物质含量的测定,推测天女木兰多酚类物质的季节变化规律;使用高效液相色谱仪定性、定量测定不同月份天女木兰不同高度叶片游离酚、结合酚和酯化酚;采用紫外分光光度法测定多酚的抗氧化性.结果表明:天女木兰叶片含有绿原酸和对香豆酸2种游离态酚;含有咖啡酸、对香豆酸2种结合酚;含有对香豆酸1种酯化酚.5月上旬开始,随着叶的发育天女木兰游离酚的含量逐渐增加,进入7月上旬,达到最高,随后含量逐渐下降;从5月上旬长叶开始至10月下旬落叶为止,总体呈现随着叶的发育酯化酚含量逐渐增加的规律,叶内结合酚呈现出非规律性的变化;5月叶片抗氧化性最弱,5月至8月抗氧化性逐渐上升,8月抗氧化性最高,8月至10月抗氧化性逐渐下降.天女木兰抗氧化性与多酚类物质含量具有相关性,确定天女木兰叶的最佳采集时期为10月上旬,即落叶前期.     

荒漠沙蜥栖息地选择的季节和地理变异

通过主成分分析、方差分析和非参数检验比较荒漠沙蜥利用生境和潜在可利用生境的9个生态因子,目的是调查其栖息地选择的地理和季节变异.研究表明荒漠沙蜥栖息地选择不存在性别差异,但存在显著的季节和地理差异.多数种群在繁殖前均选择植被盖度较低的、日晒条件好的生境,而繁殖后选择草本盖度较高、食物条件较好的生境.对照样方季节变异不明显,表明该差异主要由沙蜥的主动选择引起.繁殖前温度相对较低,沙蜥为了获得较高体温、保证生殖腺发育而选择低盖度生境;繁殖后期为了避免高温、快速积累越冬所需脂肪而选择高草本盖度生境.无论对照样方还是选择样方均存在显著的地理变异,且参数的变异模式相同,表明栖息地的地理差异与生境的差异有一定关系.此外,在不同的生境条件下,沙蜥也会权衡逃避敌害和取食的利害,而做出有利于其存活和繁殖的选择.如在灌丛盖度较高逃避捕食较容易的生境会较多地考虑日晒和取食,而在植被盖度较低食物不利时侧重取食.     

中国东部四季降水量变化空间结构的研究

利用观测资料和史料所重建的中国东部(110°E以东)71站1880—2004年的四季降水量序列,通过EOF分析得到了各个季节降水量空间分布的主要形态,并且按其特点分为两类,冬春秋季为一类,夏季为一类。利用重建的1880—1950年和观测的1951—2004年的500hPa高度场资料,分析了大气环流对各季降水异常的影响。结果表明,各季的降水异常分布形态与高空环流形势有很好的对应关系,并且近百年来这种对应关系比较稳定。最后研究了各季降水量空间结构的周期变化特征,结果显示各个季节降水量空间分布形态都存在高频的年际变化和低频的年代际变化。功率谱和子波分析表明,高频集中于2~4年、5~8年,而低频则集中在15年、20~25年、60年,共同代表了中国季节降水异常变化的主要周期。     

中国东部四季降水量变化空间结构的研究

利用观测资料和史料所重建的中国东部（110°E以东）71站1880?2004年的四季降水量序列,通过EOF分析得到了各个季节降水量空间分布的主要形态,并且按其特点分为两类,冬春秋季为一类,夏季为一类。利用重建的1880?1950年和观测的1951?2004年的500 hPa高度场资料,分析了大气环流对各季降水异常的影响。结果表明,各季的降水异常分布形态与高空环流形势有很好的对应关系,并且近百年来这种对应关系比较稳定。最后研究了各季降水量空间结构的周期变化特征,结果显示各个季节降水量空间分布形态都存在高频的年际变化和低频的年代际变化。功率谱和子波分析表明,高频集中于2～4年、5～8年,而低频则集中在15年、20～25年、60年,共同代表了中国季节降水异常变化的主要周期。     

广西北部湾沿海地区水鸟多样性及季节变动

于2010年开始,对广西北部湾沿海地区水鸟多样性及其季节分布和变动情况进行调查研究。结果广西北部湾沿海地区共调查记录到水鸟151种,隶属于8目24科,其中国家重点保护鸟类有19种。本地区水鸟以冬候鸟比例最大,占51%。水鸟多样性的季节变动巨大,夏季主要是鹭科和秧鸡科鸟类为多,到冬季鹭科鸟类减少,鸻形目鸟类大幅度增加。水鸟的时间分布大致划分为迁徙期、繁殖期和越冬期,部分水鸟的繁殖、迁徙、越冬期有交叉重叠。     

Response of global lightning activity to air temperature variation

It is an issue of great attention but yet not very clear whether lightning activities increase or decrease on a warmer world. Reeve et al. presented that lightning activities in global land and the Northern Hemisphere land have positive response to the increase of wet bulb temperature at 1000hPa. Is this positive response restricted only to wet bulb temperature or in land？ What is the response of global lightning activities （in both land and ocean） to the global surface air temperature variation like？ This paper, based on the 5-year or 8-year OTD/LIS satellite-based lightning detecting data and the NCEP reanalysis data, makes a reanalysis of the response of the global and regional lightning activities to temperature variations. The results show that on the interannual time scale the global total flash rate has positive response to the variation in global surface air temperature, with the sensitivity of 17±7% K^-l. Also, the seasonal mean flash rate of continents all over the world and that of continents in the Northern Hemisphere have sensitive positive response to increase of global surface air temperature and wet bulb temperature, with the sensitivity of about 13±5% K^-1, a bit lower than estimation of 40% K^-1 in Reeve et al. However, the Southern Hemisphere and other areas like the tropics show no significant correlation.     

转动变质量系统的相对论性变分原理和动力学方程

建立了转动变质量质点的相对论性动力学基本方程,给出了转动变质量系统的相对论性Ｄ’Ａｌｅｍｂｅｒｔ质量的几种形式,得到了有关的相对论性运动微分方程。     

Annual precipitation fields secular variation over global land areas for 1948—2000

In contrast to global temperature, fewer studies have been contributed to global precipitation. There are nu-merous efforts devoted to the problem, including Gruza[1], Diaz et al.[2], Bradley et al.[3], Vinnikov et al.[4] and Hulme[5], in which the global precipitation was addressed simply in the context of data in the 1980s, sometime be-fore that and the early 1990s[6—8]. More recently, studies have involved data around 1997 but on a local basis. Evi-dently, the problem of secular variatio…