青藏高原臭氧的准两年振荡

通过对臭氧卫星观测资料及大气环流资料的分析,研究了青藏高原上空臭氧的季节和年际变化.通过分析青藏高原地区臭氧准两年振荡(QBO),并与同纬度无山区及赤道地区臭氧QBO进行比较,指出:青藏高原臭氧QBO的平均周期为29个月,平均振幅为8DU.青藏高原臭氧QBO变化位相与热带平流层纬向风场QBO相反,即热带平流层纬向西风时,青藏高原上空臭氧总量偏小,东风时臭氧总量偏大.还讨论了与青藏高原臭氧QBO相关的大气环流物质输送理论.     

SEASONAL AND INTER-ANNUAL VARIABILITY OF THE SOUTH CHINA SEA WARM POOL AND ITS RELATION TO THE SOUTH CHINA SEA MONSOON ONSET

The South China Sea warm pool interacts vigorously with the summer monsoon which is active in the region. However, there has not been a definition concerning the former warm pool which is as specific as that for the latter. The seasonal and inter-annual variability of the South China Sea warm pool and its relations to the South China Sea monsoon onset were analyzed using Levitus and NCEP/NCAR OISST data. The results show that, the seasonal variability of the South China Sea warm pool is obvious, which is weak in winter, develops rapidly in spring, becomes strong and extensive in summer and early autumn, and quickly decays from mid-autumn. The South China Sea warm pool is 55 m in thickness in the strongest period and its axis is oriented from southwest to northeast with the main section locating along the western offshore steep slope of northern Kalimantan-Palawan Island. For the warm pools in the South China Sea, west Pacific and Indian Ocean, the oscillation, which is within the same large scale air-sea coupling system, is periodic around 5 years. There are additional oscillations of about 2.5 years and simultaneous inter-annual variations for the latter two warm pools. The intensity of the South China Sea warm pool varies by a lag of about 5 months as compared to the west Pacific one. The result also indicates that the inter-annual variation of the intensity index is closely related with the onset time of the South China Sea monsoon. When the former is persistently warmer (colder) in preceding winter and spring, the monsoon in the South China Sea usually sets in on a later (earlier) date in early summer. The relation is associated with the activity of the high pressure over the sea in early summer. An oceanic background is given for the prediction of the South China Sea summer monsoon, though the mechanism through which the warm pool and eventually the monsoon are affected remains unclear.     

Soil moisture of different vegetation types on the Loess Plateau

Water stored in deep loess soil is one of the most important resources regulating vegetation growth in the semi-arid area of the Loess Plateau, but planted shrub and forest often disrupt the natural water cycle and in turn influence plant growth. The purpose of this study was to examine the effects of main vegetation types on soil moisture and its inter- annual change. Soil moisture in 0–10 m depth of six vegetation types, i.e., crop, grass, planted shrub of caragana, planted forests of arborvitae, pine and the mixture of pine and arborvitae were measured in 2001, 2005 and 2006. Soil moisture in about 0–3 m of cropland and about 0–2 m of other vegetation types varied inter-annually dependent on annual precipitation, but was stable inter-annually below these depths. In 0–2 m, soil moisture of cropland was significantly greater than those of all other vegetation types, and there were no significant differences among other vegetation types. In 2–10 m, there was no significant moisture difference between cropland and grassland, but the soil moistures under both of them were significantly higher than those of planted shrub and forests. The planted shrub and forests had depleted soil moisture below 2 m to or near permanent wilting point, and there were no significant moisture differences among forest types. The soil moisture of caragana shrub was significantly lower than those of forests, but the absolute difference was very small. The results of this study implicated that the planted shrub and forests had depleted deep soil moisture to the lowest limits to which they could extract and they lived mainly on present year precipitation for transpiration.     

Striped weakfish (Cynoscion guatucupa) population structure in waters adjacent to Rio de la Plata,environmental influence on its inter-annual variability

The springtime temporal variations of striped weakfish (Cynoscion guatucupa) population structure available to the commercial fishery and its relationship to environmental factors were evaluated in the Uruguayan coastal zone (35° −33.4°S), from 86 stations sampled in 1994, 98, 99 and 2003. We examined the inter-annual variability of age-class structure over four years under different oceanographic conditions: (1) 1998 (El Niño year) was characterized by elevated water temperature; (2) 1999 (La Niña year) was characterized by decreased water temperature; and (3) 1994 and 2003 were ‘typical years’ with intermediate values in those parameters. To determine whether or not major shifts in population structure occurred between years we used ANOSIM and SIMPER analysis to determine which age-class typified and discriminated between years. A canonical correspondence analysis (CCA) was used to define the temporal pattern of age-class structure of C. guatucupa and to estimate its associations with environmental factors (depth, temperature, salinity, vertical stratification, and zonal and meridional component of the wind). The C. guatucupa population structure showed significant difference between 1998 and 1999 and 1994–2003. During 1998 and 1999, the population structure was dominated by adults (between 4 and >7 age-class), while that in 1994 and 2003 was dominated by juveniles (between 0 and 3 age-class). CCA results indicated that zonal wind and salinity has a major influence on the temporal pattern of C. guatucupa population structure. Juvenile population structure was associated with low salinities and occurred when the wind field forced an inflow of freshwater into the marine coastal area from the Rio de la Plata estuary, while the adult structure, associated with high salinities, occurred when the area was dominated by a wind driven inflow of higher salinity shelf water. These results support the hypothesis that the short-term environmental synoptic condition has a greater influence on the distribution and population structure of C. guatucupa than long-term environmental variability.     

1982—2001年与2002—2021年北极秋季海冰的时空变化及原因

基于北极海冰密集度、海冰范围、大气环流和海温数据,研究了1982—2001年与2002—2021年两阶段各20 a间北极秋季海冰的时空变化特征及其原因。结果表明,近20 a（2002—2021年）北极海冰密集度的下降中心由过去（1982—2001年）的楚科奇海及白令海峡一带,转移至亚欧大陆海岸的巴伦支海附近,且海冰范围每10 a减少量由0.44×10⁶ km²增长至0.72×10⁶ km²,减少速度加快约64%。秋季北极海冰范围与海水表面温度（Sea Surface Temperature,SST）、表面气温（Surface Air Temperature,SAT）及比湿（Specific Humidity）均呈显著负相关。2002—2021年的相关系数较1982—2001年有所提高,且与温度相关系数最高的月份提前了一个月。通过对海水表面温度、表面气温、比湿、气压场和风场的经验正交分解（Empirical Orthogonal Function,EOF）可知,1982—2001年间,北极地区的温度及比湿的上升中心集中在楚科奇海及白令海峡一带;2002—2021年间,上升中心则转移至巴伦支海一带。气压场和风场在前后两阶段也出现了中心转移的分布变化。北极地区大气与海洋环流各因素的协同变化影响着北极海冰的消融。     

The inter-annual variability of the Yellow Sea Warm Current surface axis and its influencing factors

Based on the Pathfinder sea surface temperature(PFSST),the surface axis and its pattern of the Yellow Sea Warm Current(YSWC) are discussed.A structure of double-warm-tongue is found in February and it varies in different years.Two indexes are calculated to represent the westward shift(WSI) and northward extension(NEI) of the warm water in the Yellow Sea(YS).Wavelet analysis illustrates that the WSI and NEI have prominent periods of 3-6 years and 3-4 years,respectively.The Empirical Orthogonal Function(EOF) ...     

根据Brewer和TOMS资料分析、验证瓦里关地区大气臭氧总量变化特征

通过对1 9 9 3年9月~2 0 0 3年1 1月瓦里关地区(3 6.1 7°N,1 0 0.5 3°E)Brewer资料和TOMS资料的比较分析,结果表明:1)瓦里关Brewer臭氧光谱仪的观测数据与卫星的TOMS观测数据之间存在一定的差异,两者的差异8 0%以上集中在-2.5%~2.5%之间;2)1 9 9 3~2 0 0 3年瓦里关地区的大气臭氧总量有着明显的下降趋势,这与北半球中纬度地区观测到的平流层臭氧减少的趋势相吻合;3)瓦里关地区大气臭氧总量存在明显的年际变化和季节变化,且每年的2~4月较高,8~1 0月较低,一年中振荡的幅度达到6 0 DU;4)TOMS两个版本的观测数据与地面观测结果呈现出较好的一致性和相关性,相关系数达到0.9以上。     

对马海峡水团组成对日本海温盐分布影响的季节及年际变化

基于WOD13(World Ocean Database 2013)的温盐观测资料,分析了对马海峡断面和日本海内一断面上温盐分布的季节变化特征,并利用水团组成混合比的方法探讨了对马海峡断面处的水团组成对日本海内断面上温盐分布的影响的季节和年际变化。研究表明:对马海峡断面上水团组成呈现显著的季节变化。冬季,整个水层被高盐水占据;夏季,对马海峡表层出现高温低盐水,底层为高盐水,次表层为表层低盐水和底层高盐水的混合水体;春秋为过渡季节。日本海断面上,秋季温盐分布最为复杂,表层为高温低盐水,次表层为高盐水,其下为低温高密水。两个断面季节变化对比可以看出,夏季对马海峡断面处的水团组成会影响秋季日本海断面上的温盐分布。夏季对马海峡表层和次表层水是秋季日本海断面表层50m以浅出现低盐水的主要原因;对马海峡深层高盐水主要影响秋季日本海断面50～150m水层,混合比可达0.82;其下为日本海固有水。夏季对马海峡处水团组成的年际变化也会影响秋季日本海断面上温盐分布的年际变化。长江流量较大的年份,夏季对马海峡表层和次表层低盐水的核心盐度值偏低,秋季其在日本海断面上的混合比就高于其他年份;对马海峡底层高盐水在日本海断面上混合比的年际变化则决定于其影响水层上的流场结构和温盐分布。     

ENSO强度模拟差异对全球变暖下热带太平洋大气变化预估结果的影响

热带太平洋海洋大气耦合系统对全球变暖的响应是气候变化的热点问题.前人研究发现,气候模式的模拟偏差对于全球变暖响应结果有重要影响.本文利用美国大气研究中心(National Center for Atmospheric Research,NCAR)的地球系统模式(The Community Earth System Model,CESM)中的大气模式(Community Atmosphere Model version 5,CAM5)设计数值试验,在相同的SST(Sea Surface Temperature)增暖强迫下,通过改变海洋SST的年际变化振幅,来分析热带海洋年际变化强度的模拟对未来热带海区降水和大气环流场未来变化的影响.试验结果表明,随着SST年际变化强度的增加,全球变暖后热带太平洋降水变化的东西不对称性,以及向暖池区域辐合的风场变化等特征都逐渐减弱.进一步的分析发现,不同年际变化信号导致的大气场变化差异主要发生在冬季,是由于热带太平洋SST年际变化主模态ENSO(El Nino Southern Oscillation)的不对称性造成的:在厄尔尼诺年,强(弱)的年际变化信号会造成降水在东太平洋产生较大(小)的变化;而在拉尼娜年和正常年份,年际变化信号的强弱对热带降水变化的影响则不大.当热带海温的年际变化较大时,厄尔尼诺年的海温异常更强,造成的降水和风场的变化特征也会更加显著.     

北京市城、郊气候要素对比研究

利用北京市市区4个站点和郊区3个站点40a的气候资料,分析了北京市城、郊平均气温、降水、日照、能见度和相对湿度的变化特征。研究发现:40a来北京市城、郊年平均气温明显上升,城区气温平均升温幅度为0.43℃/10a,郊区气温平均升温幅度为0.21℃/10a。北京市热岛效应明显增强,城、郊气温年代变化特征中,城、郊温差20世纪60年代最小,90年代最大;在城、郊气温年际变化特征中,1961～1977年城、郊温差较小,1978～2000年城、郊温差较大。在城、郊气温季变化特征中,冬季城、郊季平均气温温差最大,春季城、郊季平均气温温差最小。近几年虽然高温(≥35℃)日数明显增多,但是年最高气温变化不大,只有1997年、1999年和2000年年最高气温超过38℃。北京市年日照时数呈明显下降趋势,城区40a来日照时数下降幅度为78.9h/10a,城、郊日照时数差异随季节有不同的变化,并且秋季最大,1961～2000年秋季郊区日照时数比城区平均多0.34h。40a来北京市年降水量略有减少,且年降水量变化幅度很大,城区40a来降水量减少幅度为45.2mm/10a,由于城市化影响,下垫面性质改变,城区<10mm的降雨日数远远小于郊区,40a间城区<10mm的降雨日数比郊区少603d。1981～2000年间北京市城区水平能见度2月份、5月份、9月份和10月份较好,北京市城、郊低值能见