A local positive feedback of the tropical Pacific ocean-atmosphere system on interdecadal timescales

SINCE THE 1990S, THE CLIMATIC VARIABILITY ON INTERDE- CADAL TIME SCALES BECAME THE FOCUS OF THE INTERNATIONAL CLIMATOLOGY RESEARCH MISSIONS[1―3]. ON TIME SCALES OF A DECADE OR MORE, THE OCEAN CIRCULATION PREDOMINATEDHEAT BALANCE AND HYDROLOGICAL CYCLE, S…     

An integrative estimation model of summer rainfall-band patterns in China

Three variation indices are defined to objectively and quantitatively represent fluctuations of three rainfall-band patterns in summers in China for the period from 1951 to 2005, and the variation features of these indices are analyzed on both of interdecadal and interannual scales. A new method is proposed to establish an integrative estimation model based on the analysis of rainfall-band indices, and the model is applied to air, ocean factors to estimate their roles on variations of three rainfall-band patterns on different time-scales. The tests of estimation effects show that the fluctuations of three rainfall-band patterns are composed of variations on both significant inter-decadal and interannual scales, of which the interannual variation is mainly influenced by the Elnino/Lanina events, the East Asia monsoon and the ridge locations of subtropical high pressures in western pacific, while the interdecadal variation is mainly controlled by the Pacific decadal oscillation and interdecadal oscillations of the Arctic oscillation, ENSO, Nino3 sea surface temperature and summer monsoon. The estimated results from the integrative estimation model of rainfall-band patterns suggest that the way of estimation first according to each time scale of both the interdecadal and interannual scales, then estimating with an integration, which is proposed in this paper, has an obvious improvement on that without separation of time scales.     

An integrative estimation model of summer rainfall-band patterns in China

Three variation indices are defined to objectively and quantitatively represent fluctuations of three rainfall-band patterns in summers in China for the period from 1951 to 2005, and the variation features of these indices are analyzed on both of interdecadal and interannual scales. A new method is proposed to establish an integrative estimation model based on the analysis of rainfall-band indices, and the model is applied to air, ocean factors to estimate their roles on variations of three rainfall-band patterns on different time-scales. The tests of estimation effects show that the fluctuations of three rainfall-band patterns are composed of variations on both significant inter-decadal and interannual scales, of which the interannual variation is mainly influenced by the Elnino/Lanina events, the East Asia monsoon and the ridge locations of subtropical high pressures in western pacific, while the interdecadal variation is mainly controlled by the Pacific decadal oscillation and interdecadal oscillations of the Arctic oscillation, ENSO, Nino3 sea surface temperature and summer monsoon. The estimated results from the integrative estimation model of rainfall-band patterns suggest that the way of estimation first according to each time scale of both the interdecadal and interannual scales, then estimating with an integration, which is proposed in this paper, has an obvious improvement on that without separation of time scales.     

Simulation or meridional overturning in the upper layer of the South China Sea with an idealized bottom topography

The large-scale upper circulations and meridional overturning in the upper layer of the South China Sea (SCS) with idealized bottom topography in winter and summer are investigated. Simulations with the GFDL general circulation model are carried out under the conditions of open or enclosed boundary regarding transport in the Luzon Strait. The intrusion area of Kuroshio, its impact on the meridional overturning in the upper layer of the SCS and seasonal characteristic of this impact are explored, respectively. The model is forced by climatological wind stress and relaxed to monthly mean climatological temperature and salinity. The resultant meridional overturning is non-enclosed, wit htransporting from north to south in the surface and returning to north at the depth of about 500 m in winter, about 200 m in summer, with amplitudes of 10^5 m^3/s. It shows the transporting path of intermediate water of the SCS and offers an idealized reference for further study on dynamics of wind-driven and thermohaline circulation of the SCS.     

Simulation of meridional overturning in the upper layer of the South China Sea with an idealized bottom topography

The South China Sea (SCS) is the largest marginal sea in the northwestern Pacific. Several important water gateways exist around the SCS, such as Luzon Strait, Taiwan Strait, etc., that lie in the northeastern SCS, and others like Kalimantan Strait, Balawan Strait, etc., lie in the south. Luzon Strait connects the SCS and Pacific via the Philippine Sea, and its water exchange has significant impact on the interior circulations of the SCS[1]. Since direct observation data about the …     

Movement of earth rotation and activities of atmosphere and ocean

The rotation of the earth, including the variation of the rotational rate and polar motion, represents the statement of the earth’s overall movement and interactions among the solid earth, atmosphere and ocean on a variety of space-time scales. They make the earth’s complex dynamical system under the conservation of angular momentum. The application and development of recent space geodetic techniques greatly promote the researches on the interactions between the earth rotation and the activities of atmosphere and ocean. This review will mainly report the progress in researches on the earth rotation and the activities of atmosphere and ocean as well as the air-sea interaction in the tropics, and prospect the direction for future theoretical investigations.     

钢塔对间冷散热器换热性能的影响

利用计算传热学软件Fluent,在自然通风状态下,对国内首个2×660 MW机组钢结构外覆铝板冷却塔间接空冷散热器的流动和换热性能进行数值模拟、分析和研究.考核工况下,水平加强环对散热器换热量和钢塔通风量的影响约占设计值的2.7%;铝板换热量约占机组排热量的0.6%;随着环境风速的增大,钢塔抽力逐渐降低;当环境风速高于10m/s时,出现塔内热空气流出冷却柱的现象;当环境风速高于20m/s时,塔内出现"穿堂风",间冷散热器的换热量和钢塔通风量明显增加;当环境风速低于12m/s时,随着环境风速的增大,间冷散热器的换热量和钢塔通风量逐渐降低;当环境风速高于12m/s时,随着环境风速增加,间冷换热量和钢塔通风量呈增大趋势.     

平鲁县风能资源状况分析

通过对平鲁区近30年风观测资料的综合分析,发现平鲁区多年年平均的风速日变化范围在2.5m/s～5m/s之间,风速的日变化主要随太阳辐射的变化而变化,风速的大小受太阳辐射、下垫面和地形影响较大。指出平鲁区每年4月份的风速最大,3月份风速次大,全年风速最大的季节在春季,冬季次之,夏季风速最小;全年的风能主要是由西北偏西风和西风提供,这两个风向的风能占到总风能的72%;多年的年平均风速没有明显的增大或减少趋势。     

Aerosol influence domain of Beijing and peripheral city agglomeration and its climatic effect

In recent years, along with development of industries and intensification of human activities, aerosol influ- ence and its climatic effect, and the aerosol-associated “aberrance” cloud phenomenon have increasingly drawn people’s attention. The term “A…     

基于耦合气候系统模式的中全新世黄、东海海表通量分析

对中全新世(6,ka时期)海洋和气候的研究可加深人们对现阶段气候变化和海洋环境的认识,为预测未来海洋与气候环境变化提供一个重要参照.文章分析一个耦合气候系统模式FGOALS-s2.0的模式结果,首先对其工业革命前(0,ka时期)东亚地区夏季降水及冬、夏季10,m风场的模拟结果进行评估,然后进一步对中全新世和工业革命前黄、东海海表大气强迫的季节变化进行了对比.结果显示:模式模拟出0,ka时期东亚夏季降水从东南洋面至西北内陆减少的空间分布特点,冬、夏季10,m风场亦与观测大体一致;6,ka时期夏季,黄、东海风速较0,ka时期增大约0.8,m/s,16%左右;黄海风应力旋度值为正,东海为负,与0,ka时期相比旋度绝对值均增大;同时,两海区接收的太阳短波辐射较0,ka时期均增加,短波辐射的差异是中全新世夏季黄、东海海表的净热吸收增加的主要因子.6,ka时期冬季,黄、东海北风加强,东海增加量在0.5~1.0,m/s,幅度约为10%,较黄海更为明显;两海区在冬季的净热释放也较0,ka时期增大,东海释放更甚;冬季黄、东海风应力旋度较0,ka时期则无太大差别.研究表明,由于6,ka时期太阳辐射季节循环的改变,造成了黄、东海夏季风增强,海表净热通量也发生相应变化,该时期大气强迫场的变化可能会使黄、东海表层水温分布趋势发生较大改变,进而影响陆架环流格局.     

玉华矿矿井通风系统的综合评定

通过计算玉华矿矿井风量、风压及等积孔,对该矿井通风系统进行了综合评定。矿井移交生产及达到设计生产能力时,矿井总进风量为135m3/s;通风容易时期风压为1650.54Pa,通风困难时期风压为2917.09Pa;矿井通风容易时期和困难时期等积孔分别为3.95m2和2.97m2,属通风小阻力矿井。     

A comparative study on 3-D solar wind structure observed by Ulysses and MHD simulation

Ulysses, which was a joint NASA/ESA probe to studythe sun and launched in October of 1990, has been thefirst spacecraft to explore the high latitudinal regions ofheliosphere till now[1]. One of its main scientific purposeswas to observe the latitudinal structures of solar wind pa-rameters, such as velocity, density, mass flux, magneticfield, etc.[1―4]. During its first rapid pole-to-pole transitcovering heliographic latitudes of ±80° from September of1994 to June of 1995, Ulysses observ…     

吕泗上升流观测和动力机制模拟分析

基于2000年8月长江口外现场观测的分析,首次发现在长江口外吕泗附近存在着上升流现象.该上升流将下层的冷水和营养盐带向上层,对海区的环境和生态具有重 要的影响.为了解该上升流的动力机制,作者利用基于ECOM_si建立的一个水平球面坐标系的高分辨率湍流闭合的三维环流数值模式研究该上升流现象.该模式计算区域包括东海、黄海和渤海,考虑实际岸线和水深.在综合考虑风应力、开边界体积通量和密度梯度力的情况下,模拟结果再现了吕泗海区的上升流现象,与观测结果较为一致.数值试验结果表明,产生该处上升流的动力机制主要是盐淡水混合产生的斜压效应,风应力的作用较弱,边界水体积通量产生的正压效应不起作用.倾斜的底形与斜压效应、风应力的联合作用使吕泗海区的上升流更明显.     

近10年南海海表风场季节特征统计

基于Fortran程序和Grads(Grid Analysis and Display System)软件,利用QN(QuikSCAT/NCEP)混合风场,统计了近10年(1999年8月~2009年7月)期间南海海表风场特征,主要统计了风速风向的季节特征,期望研究结果可以为航海、防灾减灾等提供参考。结果表明:(1)春季,风速的大值区位于南海北部,约3.5~5.0 m/s,台湾海峡能达到5.5 m/s;除泰国湾和北部湾以外的大部分海域以东北风为主,北部湾以偏东风为主,泰国湾以偏南风为主。(2)夏季,受西南季风影响,大部分海域以西南风为主;风速的大值区位于中南半岛附近海域,该海域为传统的南海大风区,约5~7 m/s。(3)秋季,为季风过渡季节,风向稍显凌乱,南海中北部已转东北风,而南部部分海域的西南风尚未完全消退,泰国湾在该季节则以西北风为主;风速的相对大值区位于南海北部和台湾周边海域,约6~9 m/s,台湾海峡基本都在9 m/s左右。(4)冬季,受冷空气影响显著,整个南海均以强势的东北风为主;风速大值区呈东北-西南走向,大部分海域的风速在8 m/s以上,台湾海峡能达到11 m/s左右。     

Seasonal features of the Sverdrup circulation in the South China Sea

Based on the Sverdrup relation, using climatological wind stress data, the basin scale Sverdrup transport in the South China Sea(SCS) is calculated and the basic seasonal features of the Sverdrup circulation are obtained. A comparison of these calculated features with observations proves that the wind-driven circulation in the SCS is very important for the formation of the SCS upper oceanic circulation in winter, summer and fall. It is shown that the non-uniform sea surface wind is one of the causes to form multi circulation centers in the basin of the SCS. The westward current at 18°N is caused by the local wind, which is stronger in fall and winter. The seasonal variation of circulation in the southern SCS is much more remarkable than that in the north. The wind in spring is helpful to the seasonal reversal of the circulation in the central SCS. The northward transport of the cyclonic circulation reaches the maximum in fall.     

1997～1999年亚洲季风区夏季水汽输送的差异分析

 利用ECMWF的水汽和风场资料,对东亚、东南亚和印度季风区1997～1999年各年夏季(6～8月)300～1000hPa气层间的水汽输送及其差异进行了计算分析.结果表明:①水汽输送的经向通量,在印度尼西亚-中国南部-日本南部为向北(正)的通量,从1997年到1999年夏季经向通量是由弱变强再变弱,而在澳大利亚北部-印度尼西亚则是由强变弱再变强;②水汽输送的纬向通量,1997年夏季正输送的东西范围比1998年和1999年夏季要广,但南北范围较窄;③中国东南部、南海到日本东部海域的负水汽平流在1998年夏季最大;④风场散度引起的水汽通量散度,在阿拉伯海和孟加拉湾1998年夏季最小,在东亚和西太平洋地区这3年变化很大.     

Reduction of the East Asian winter monsoon interannual variability after the mid-1980s and possible cause

The East Asian winter monsoon (EAWM) consists of subsystems such as the Siberian high, Aleutian low, East Asian trough, low-level northerly wind and high-level East Asian jet stream. It is revealed that the interannual variation of the EAWM-related atmospheric circulation has exhibited an obvious weakening since the mid-1980s. During 1956-1980, significant negative correlations between the EAWM and sea surface temperature are observed in the oceans along the east coast of East Asia, accompanied by significant positive correlations in the western Warm Pool. However, the significant interannual relationship in the previous period is found to have been disrupted during 1986-2010. Further analysis reveals that the Arctic Oscillation after the mid-1980s tends to suppress the interannual variability of the EAWM. In addition, it was found that the large-scale warming after the mid-1980s is favorable to reduce the land-sea thermal contrast variability on both the interdecadal and interannual time scales.     

Comparison of phylobetadiversity indices based on community data from Gutianshan forest plot

Phylobetadiversity incorporates phylogenetic information and beta diversity,and can account for the ecological similarities between communities with a phylogenetic perspective.Although different phylobetadiversity indices reflect differences in different characteristics between communities,the results of different phylobetadiversity indices are not comparable.In this study we examined phylobetadiversity indices for a 24-hm 2 plot in the Gutianshan National Nature Reserve.It was found the abundanceweighted D pw was almost identical to Rao’s D of Rao’s quadratic entropy.PhyloSor had a similar ecological meaning and algorithm to UniFrac.Although Dnn was different in definition from UniFrac and PhyloSor,they were all strongly correlated.The effect of species abundance on phylobetadiversity was not significant when scales were relatively small,but was significant at larger scales.These contrasts likely resulted from reductions in evenness in communities as scales increased.P ST and Rao’s H better reflected the distance-decay changes caused by spatial and habitat variation than other indices at larger scales,whereas AW-D nn and D nn better reflected these changes at small scales.     

百余年上海冬夏季降水与太平洋海温的相关关系及其年代际差异

利用上海1873—2001年的冬季和夏季降水量与太平洋海温资料，通过计算上海冬季和夏季降水量与太平洋海温的同期和超前相关以及滑动相关系数，讨论上海冬季和夏季降水年代际变化趋势及其与太平洋海温场的相关关系在不同年代和不同空间区域上的显差异．分析发现，上海冬季和夏季的降水均存在明显的年代际阶段性变化，但总体雨量增加的趋势不明显，降水量和太平洋海温的相关关系在不同年代和不同空间区域上存在着显的差异，这种年代际相关关系的差异可能是造成用统计方法做短期气候预测时产生不确定性的主要原因之一．因此作为短期气候预测的常用预报因子之一的太平洋海温场在进行统计预报的应用过程中，适当地考虑在不同时间尺度上的相关差异，将有利于提高预测的准确性和减少统计预测方法中的不确定性．     

单室火灾烟气运动的双层区域模拟

室内火灾双层区域模拟中需考虑到压力的变化,利用热力学第一定律推导了室内气体参数随时间变化的常微分控制方程组.该方程组刚性,可采用吉尔算法求解.在选用Heskestad羽流公式的基础上,计算了某单室火灾在房间平面面积与机械排烟量分别为49m2,0.3m3/s;49m2,0.4m3/s;100m2,0.3m3/s;100m2,0.4m3/s四种工况下室内与室外压差、烟层高度、上层烟气温度、下层空气温度随时间的变化规律.结果显示:室外压差随时间变化迅速;Heskestad与Mcaffrey羽流模型在算例中具有较好相似性;烟层的下降与上层烟气温度的升高较多地受到房间平面面积的影响,而受顶部排烟量的影响较少.