东太平洋冷舌区海表面温度日变化特征的模拟研究

本文通过分辨太阳辐射日变化, 利用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 (LASG/IAP) 气候系统海洋环流模式 (LICOM), 模拟了东太平洋冷舌区海表面温度 (SST) 的日变化特征并研究了弱混合对其影响。采用理想的太阳辐射日变化强迫上层垂向分辨率为10 m的海洋模式LICOM, 模拟出了SST日变化一些特征, 同时海洋的上层流场也产生明显日变化。模拟的SST日变化振幅水平分布与观测接近, 且受太阳辐射日变化振幅水平分布调制。在赤道中东太平洋区, 模拟的SST日变化振幅 (约为0.3～0.4℃) 比观测偏小约0.1～0.2℃。模拟的SST日变化峰值出现在15～16 时 (当地标准时间), 落后于太阳辐射峰值2～3个小时, 接近观测。进一步减弱混合后, 模拟的日变化振幅增加约0.1℃, 更接近观测。这说明在东太平洋冷舌区SST日变化主要受太阳辐射日变化和垂直混合影响。此外, 混合减小后, 在太阳辐射日变化调制下, 平均态 (如混合层、温度和流场) 也出现明显变化。在赤道东太平洋冷舌区北侧, 弱混合导致混合层变浅, 变浅使热量堆积进而使平均SST升高约0.3℃; 在赤道东太平洋冷舌南侧, 经向平流加强导致平均SST降低约0.2℃。     

东北冷涡活动的季节内振荡特征及其影响

东北冷涡是造成我国东北地区低温冷害、持续性阴雨和突发性强对流的重要天气系统.利用1979～2009年NCEP/NCAR逐日再分析资料和中国气象科学研究院提供的中国区域高分辨率格点降水资料,定义了一个客观描述东北冷涡活动的指数 (NECVI),并基于该指数分析了东北冷涡活动的低频特征及其与相关环流和降水的关系.结果表明,东北冷涡活动具有显著的10～30天振荡周期.与东北冷涡活动相关的大气环流的10～30天振荡和我国东部夏季降水异常具有明显的锁相关系,对雨带的位置起着重要的调制作用,在东北冷涡及其相关低频环流由西北向东南的移动过程中,我国东部也经历一次由北至南的降水过程.本文还进一步讨论了东北冷涡的低频活动与中高纬大气环流遥相关型的关系.与东北冷涡相联系的低频环流是夏季低频欧亚 (EU) 型遥相关波列的一部分,低频欧亚型 (EU型) 与东亚/太平型 (EAP型) 遥相关波列在东亚地区交汇,并通过波列之间的相互作用影响东北冷涡低频系统的移向和移速,进而影响中国东部降水的位置与维持时间.因而前期EU型和EAP型低频波列的发展情况可能预示着后期中国东部各个区域降水的演变.本文研究结果将为提高我国东部强降水的1～2周延伸期天气预报提供参考.     

Hydrography and Circulation in the Eastern Tropical Indian Ocean during April-May 2011

The distribution of hydrography and circulation in the eastern tropical Indian Ocean(ETIO) during April-May 2011 were analyzed using cruise observations,satellite observations,and historic hydrographic data.It was observed that warm water(28℃) occupies the upper 50-m layer in the ETIO.Low-salinity surface water was observed at the mouth of the Bay of Bengal(BOB),which further extends to the Arabian Sea and off Sumatra via the Sri Lanka coast and the eastern bay mouth.Arabian Sea high-salinity water(ASHSW) is carried eastward along the equator to around 90°E by the equatorial undercurrent(EUC).It also runs south of Sri Lanka(north to 3°N) and in the western bay mouth(west to 87°E) but is much shallower than its counterpart at the equator.It is suggested to be the residual of the ASHSW,which intrudes into the BOB during the preceding southwest monsoon.Our results also show that,in the south of Sri Lanka,just below this subsurface high-salinity water,very-low-salinity water(about 34.8) occurs at depths of 100-200 m.Further analysis suggests that this low-salinity water comes from the BOB.     

2008年初云南低温雨雪冰冻天气的气候成因分析

2008年1月下旬~3月上旬云南出现了一次持续性的低温雨雪冰冻天气, 给交通、 电力、 通讯以及人民的生产、 生活带来了极大危害。本文首先对云南高低层大气的异常状况及大尺度环流背景场特征对这次天气过程的影响进行诊断分析, 然后进一步探讨了赤道东太平洋海温异常对东亚冬季风活动和云南天气气候异常的影响。结果表明, 这次低温冷害过程主要发生在冷空气由北至南逐渐加强南压, 南支西风波动配合, 以及西太平洋副热带高压减弱东退的大尺度环流背景之下。同时, 云南区域的大气异常状态表现出了明显的高湿、 强上升运动以及对流层中高层温度升高而低层温度降低。另外, 本文分析还进一步表明了2008年赤道东太平洋地区的冷海水异常对这次云南低温冷害天气过程的重要作用。     

Impacts of Future NOx and CO Emissions on Regional Chemistry and Climate over Eastern China

A coupled chemical/dynamical model (SOCOL-SOlar Climate Ozone Links) is applied to study the impacts of future enhanced CO and NOx emissions over eastern China on regional chemistry and climate. The result shows that the increase of CO and NOx emissions has significant effects on regional chemistry, including NOx, CO, O₃, and OH concentrations. During winter, the CO concentration is uniformly increased in the northern hemisphere by about 10 ppbv. During summer, the increase of CO has a regional distribution. The change in O₃, concentrations near eastern China has both strong seasonal and spatial variations. During winter, the surface O₃, concentrations decrease by about 2 ppbv, while during summer they increase by about 2 ppbv in eastern China. The changes of CO, NOx, and O₃, induce important impacts on OH concentrations. The changes in chemistry, especially O₃, induce important effects on regional climate. The analysis suggests that during winter, the surface temperature decreases and air pressure increases in central-eastern China. The changes of temperature and pressure produce decreases in vertical velocity. We should mention that the model resolution is coarse, and the calculated concentrations are generally underestimated when they are compared to measured results. However, because this model is a coupled dynamical/chemical model, it can provide some useful insights regarding the climate impacts due to changes in air pollutant emissions.     

热带东印度洋海表温度持续性的秋季障碍

利用全球海表海温资料(GISST)和NCEP/NCAR再分析风场、海平面气压场资料,研究了热带东印度洋海表温度持续性的季节差异,发现东印度洋海温持续性存在"秋季障碍"现象。进一步分析了东印度洋"秋季障碍"后冬季海温与中东太平洋海温、海平面气压及850hPa风场的关系,并讨论了热带印度洋—太平洋地区海气系统的季节变化与东印度洋"秋季障碍"的关系,结果表明,秋季热带印度洋—太平洋地区海气系统由以印度洋季风环流为主导转向以太平洋海气系统为主导,太平洋海气系统处于急剧加强期,增强的太平洋海气系统对东印度洋海温持续性"秋季障碍"起着重要的作用。     

1953-2005年内蒙古东部产粮区气候变化特征研究

利用系统聚类分析和相关分析方法,根据1953--2005年内蒙古东部产粮区48个气象站的气象资料．进行了气候相似区划分;并得出各区在热量、水分的时间变化上具有较高的区域一致性。据此,以区域内各站点的温度、降水和日照时数的平均值作为区域热水光时间序列,分析了各气候要素变化特征及其对农业可能产生的影响。结果表明：各区域温度呈上升趋势,增温速率（平均增温为0．3-0．4℃／10a）高于中国平均增温速率（0．22℃／10a）,增温幅度呈从西向东递增的趋势,平均最低气温增幅最大,平均最高气温增温幅度与海拔呈正相关,尤以1988年以后变暖趋势最为明显;降水量基本呈减少趋势,年代际波动较大;20世纪90年代至今,内蒙古东部产粮区生长季降水明显减少,气温迅速升高,暖千化趋势表现明显,温差减小和日照时数减少,水热匹配格局发生改变,粮食产量出现减少趋势的可能性较大。     

强降水时蒸发常见错情及措施

对山东省2009年7-8月报表错情统计,发现强降水时蒸发错情达18.6条,其原因是观测员对《地面气象观测规范》理解不够准确,审核员过于武断,对规范理解过于僵化,将观测员处理正确的记录统计为错情.对德州2000-2010年及平原2008-2010年强降水时对蒸发所采取的措施比较得出:液态降水采用增加溢流桶法效果最好,但它不适用固态降水;加盖法简单易行,适用于液态和固态降水,但只适用于守班期间.因此针对不同降水性质,应采取不同措施,确保蒸发记录的准确性.     

Formation and alteration of plagiogranites in an ultramafic-hosted detachment fault at the Mid-Atlantic Ridge (ODP Leg 209)

We examined small-scale shear zones in drillcore samples of abyssal peridotites from the Mid-Atlantic Ridge. These shear zones are associated with veins consisting of chlorite + actinolite/tremolite assemblages, with accessory phases zircon and apatite, and they are interpreted as altered plagiogranite melt impregnations, which originate from hydrous partial melting of gabbroic intrusion in an oceanic detachment fault. Ti-in-zircon thermometry yields temperatures around 820°C for the crystallization of the evolved melt. Reaction path modeling indicates that the alteration assemblage includes serpentine of the adjacent altered peridotites. Based on the model results, we propose that formation of chlorite occurred at higher temperatures than serpentinization, thus leading to strain localization around former plagiogranites during alteration. The detachment fault represents a major pathway for fluids through the oceanic crust, as evidenced by extremely low δ¹⁸O of altered plagiogranite veins (+3.0–4.2‰) and adjacent serpentinites (+ 2.6–3.7‰). The uniform oxygen isotope data indicate that fluid flow in the detachment fault system affected veins and adjacent host serpentinites likewise. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

中国东部陆下岩石圈地幔中的再循环地壳流体组分

地幔捕虏体中的流体组分记录了地幔演化的信息,可用来认识地幔中再循环地壳组分的性质和来源。采用分步加热质谱法测定中国东部二辉橄榄岩捕虏体组成矿物中流体挥发份的碳、氢和氧同位素组成,结合化学组成(Zhang et al., 2004)综合分析表明,早期流体包裹体、矿物晶格缺陷和空隙中的流体挥发分主要在高温段(800-1200°C)释出,CO2和CO显示较轻的δ13C值,与世界其它地区地幔捕虏体明显不同;晚期流体包裹体中的流体挥发分主要在低温段(300-600°C)释出。根据中国东部地幔演化事件、地幔矿物性质认为陆下岩石圈地幔中三种类型的流体挥发份中均存在来源不同的再循环地壳组分：（1）地幔初始流体：主要为耐熔矿物橄榄石在800-1200°C释出的流体组分,华北克拉通地幔初始流体的化学组成（主要为CO）与华南克拉通（主要为CO2）明显不同,反映二者拼合前各自演化时期捕获的流体组分。地幔特征的δD、δ13CCH4和δ18OCO2反映初始流体组分可能为元古代克拉通大陆型岩石圈地幔成分,较轻的CO2 和 CO的δ13C值揭示初始流体中存在部分再循环地壳流体,可能在1.9Ga的大陆碰撞过程中混入。（2）地幔交代流体：指斜方辉石和单斜辉石800-1200°C释气峰的流体组分,以H2为主。华北克拉通交代流体主要组分H2含量(80.73 mm3.STP/g) 明显低于华南克拉通(138.91 mm3.STP/g),地幔特征的δDH2和δ13CCH4表明交代流体主体为地幔来源,较轻的δ13CCO2,CO和较重δ18OCO2揭示其中存在再循环陆壳流体,其可能的来源为华北与华南中生代拼合过程中的壳幔相互作用。（3）岩石圈减薄流体：指二辉橄榄岩捕虏体组成矿物在400-600°C释放出的流体,华北与华南克拉通在流体组成方面相似,壳源特征的CO2、CO和CH4的δ13C值,以及较轻的δ18OCO2和δDH2O值指示该流体可能为岩石圈地幔减薄过程中引起的再循环洋壳流体,可能与中国东部转换带中水平俯冲的太平洋岩石圈(或其前身)脱气有关。