A NUMERICAL STUDY FOR MECHANISM OF THE EFFECT OF NORTHERN SUMMER ARCTIC ICE COVER ON THE GLOBAL SHORTRANGE CLIMATE CHANGE          下载免费PDF全文

Ni Yunqi  Zhang Qin  Li Yuedong 《Acta Meteorologica Sinica》1992,6(1):15-24

In terms of nine-layer global spectral model involving fuller parameterization of physical process,with arhomboidal truncation at wavenumber 15,experiments are conducted by virtue of two numerical schemes,one withlong-range mean coverage of Arctic ice,and the other with supercooled water at the same temperature as the ice,fol-lowed by an analysis of the difference field simulated by the two schemes.Results show that(1)the impact of Arctic iceon the northern short-range climate is realized through the change in polar ice coverage to cause local temperaturechange in the polar region to set up gradient difference in temperature from north to south,thus affecting the atmospher-ic circulations and,on the other hand,two trains of two-dimensional Rossby waves excited by the atmospheric heatsource anomaly have impacts on the Northern Hemisphere(NH)extratropical region,one of which is similar to the JPteleconnection pattern first presented by Nitta(1987);(2)The significant impact of Arctic ice anomaly on the southernshort-range climate change is accomplished with the aid of the anomaly of the equatorial heat source that excites a two-dimensional Rossby wavetrain propagating along a great circle route into the Southern Hemisphere(SH)extratropics,and the cross-equatorial propagation of the NH wavetrain also has effects on the SH atmosphere.Simulation indicatesthat with the 15-day integration the Arctic ice exerts an influence mainly on the NH and when the model atmosphere isgetting stabilized,the effect is dominantly on the SH short-range climate change.  相似文献   

Lg amplitude ratios H/Z and station terms in the six eastern provinces of China     

Huancheng Ge  Caizhong Huang  Yuewei Ni  Yongqin Li 《地震学报(英文版)》1992,5(2):257-261

Using the data set of about 1 Hz Lg amplitudes from 80 stations in the six eastern provinces of China, the ratios of horizontal to vertical amplitude of Lg waves,H/Z are determined. The mean lg(H/Z)-value is equal to 0.13. For the station bases of soft deposit,granite and sedimentary rock, lg(H/Z)-values average 0.55, 0.04 and 0.10, respectively. For the three kinds of station bases, the station terms of horizontal amplitude,C _h average 0.65, −0.09 and 0.00; that of vertical amplitude,C _z average 0.32, −0.04 and 0.00, respectively. There are the relations betweenC _h ,C _z and lg(H/Z):C _h =0.01+2.10C _z andC _h =−0.15+1.46 lg(H/Z). The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 281–286, 1991. Project sponsored by the Chinese Joint Seismological Science Foundation.  相似文献   

Moment tensor inversion of some aftershocks of the April 18, 1985 Luquan earthquake of Yunnan Province, China     

Jiangchuan Ni  Yuntai Chen  Ming Wang  Mingxi Wu  Jiayu Zhou  Peide Wang  Francis T. Wu 《地震学报(英文版)》1992,5(3):459-467

Based on the three component accelerograms, recorded at near-field distance by a temporary seismic network consisting of digital cassette tape recording accelerographs, the focal mechanisms of three aftershocks of the April 18, 1985, Luquan, Yunnan Province, China, earthquake ofM _S=6.1, are calculated using seismic moment tensor inversion technique. The phases of direct P, S and converted SP waves in the displacement seismograms, produced by twice integrations of the observed accelerograms, are identified via forward calculation using Green’s functions for homogeneous semi-infinite elastic medium, and used in the inversion. The results of inversion show that a better fit of synthetic to the observed seismograms of direct as well as converted phases can be achieved if appropriate weighting functions are used in solving the over definite linear equations. While these aftershocks are of different magnitudes (M _L=4.8, 3.2 and 3.5, respectively) and hypocentral locations, their focal mechanisms are very similar and consistent with that of the main shock. This feature demonstrates the intrinsic correlation between the occurrence of aftershocks and the seismogenic fault of main shock. Our experimentations show that using the near field accelerogram obtained from the digital seismic network with appropriate azimuthal coverage on the focal sphere, with the aid of even simple medium model, not only the shear dislocation source, but also the isotropic part and CLVD (compensated linear vector dipole) can be retrieved by the technique of moment tensor inversion. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 412–419, 1991. This work is supported by the Chinese Joint Seismological Sciences Foundation and the Western Yunnan Earthquake Prediction Test Site (WYEPTS), State Seismological Bureau.  相似文献   

Study of the characteristics of earthquake precursory anomalies of He and H₂ Beijing No. 2 Cotton Mill well and their relation with earthquakes     

Shu-Quan Fan  Sheng-Hu Su  Ni Li 《地震学报(英文版)》1993,6(4):959-969

This paper systematically summarized the relation of the abnormal change of He and H₂ dissolved gasses in deep hot-water well at Beijing No. 2 Cotton Mill and their relation with seismicity of the region. An empirical formula for the relation of the precursory anomaly of He and H₂ gasses with the magnitude and occurrence time of earthquake has been derived. Two events of magnitude greater than 5 in North China had been successfully predicted by using this formula. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 490–497, 1993.  相似文献   

Study of the characteristics of earthquake precursory anomalies of He and H2 Beijing No. 2 Cotton Mill well and their relation with earthquakes     

Shu-Quan Fan  Sheng-Hu Su  Ni Li 《地震科学（英文版）》1993,6(4):959-969

This paper systematically summarized the relation of the abnormal change of He and H₂ dissolved gasses in deep hot-water well at Beijing No. 2 Cotton Mill and their relation with seismicity of the region. An empirical formula for the relation of the precursory anomaly of He and H₂ gasses with the magnitude and occurrence time of earthquake has been derived. Two events of magnitude greater than 5 in North China had been successfully predicted by using this formula.  相似文献   

我国干旱地区一次直升机自然结冰试飞天气个例分析     

王泽林  倪洪波  裴昌春 《沙漠与绿洲气象(新疆气象)》2020,14(2):68-74

2018年3月17日、27日,国产某型直升机在新疆五家渠地区成功完成2架次自然结冰试飞。利用NCEP/NCAR的1°×1°再分析资料、机测液态水含量资料结合常规气象资料,对2次结冰天气过程的天气环流形势、动力热力特征、液态水含量进行分析。结果表明:17日在高空冷涡、地面冷锋前的环流形势下,试飞高度层位于冷暖平流交汇处,温度为0～-4℃,比湿值为3～3.5 g/kg,处于强水汽辐合中心,并伴有弱上升运动,Ic积冰指数为20～30,云中液态水含量波动较大,飞机挂架上形成0.5 cm厚度的凇冰。27日在高空槽前和地面冷锋后的环流形势下,试飞高度层在弱冷平流中心附近,温度为0～-2℃,比湿值接近4.5 g/kg,处于弱水汽辐合中心边缘,伴有弱上升运动,Ic积冰指数为30～40,云中液态水含量稳定,飞机挂架上形成1～2 cm厚度的明冰。在气象保障中运用探空、云图、雷达、微波辐射计等资料有效预报了积冰区域及高度。  相似文献   

基于年际增量法的华西秋雨预测模型建立及检验     

王春学  郑然  李栋梁  唐红玉  马振峰  茅海祥 《气象科技》2020,48(6):855-861

利用1962—2018年华西地区301个气象台站秋季降水量资料和国家气候中心整理的130项气候系统指数，采用年际增量法建立了华西秋雨预测模型。首先通过相关分析挑选了4个与华西秋雨年际增量前3主模态密切相关的影响因子，进而采用多元线性回归方法进行建模，拟合时段和后报时段分别选为1962—1991年和1992—2018年。华西秋雨年际增量前3主模态累积值的预测模型通过了α=0.01的显著性水平检验，表明该模型具有较高的拟合预测能力。然后用相同的预测因子分别建立华西地区301个气象站点的华西秋雨年际增量预测模型，大部分模型都通过了显著性检验。用PS评分指标对预测效果进行检验，结果显示后报期年平均PS评分达74.5分。从空间分布来看后报期大部分站点的PS评分都超过60分，其中四川盆地南部、贵州东部和湖南西部等地超过80分。与华西各省和国家气候中心发布的近6年秋季降水预测PS评分进行比较，发现模型后报结果有显著优势。总体来看，用年际增量法建立的华西秋雨预测模型具有较高的预测技巧和实际应用价值。  相似文献   

DIAGNOSIS ON LOW FREQUENCY COMPONENT OF ENSO VARIABILITY—PART Ⅱ:ORIGIN OF THE COMPONENT     

邹力  倪允琪 《Acta Meteorologica Sinica》1997,(1)

Diagnosis is undertaken on the origin for the low-frequency component (LFC) of ENSOvariability in the context of 1979—1990 OLR and u-wind datasets.Evidence suggests that ① apower spectrum-yielded maximum,significant statistically,is derived from the OLR monthlyanomalies in a 3—5-year period range over the tropical central/western Pacific;②compositeanalysis of the signals of the monthly anomaly low frequency component (period>3 years)confirms further the dynamic features of the component as documented in Part Ⅰ:③serving asforcing on ENSO,the related monsoon region represents the source area of the component;④theone-point correlation maps of unfiltered OLR monthly anomalies with zonal wind on a lagged,asimultaneous and a leading basis show clearly the close relation between the u wind-associatedeastward travelling low-frequency wave and the low-frequency oscillation of low-latitude central/western Pacific large-scale convection and the east-moving mode is likely to be excited by theoscillation at a 3—5-year period range.It follows that the large-scale convection oscillation showsup as the origin of the eastward waves,i.e.,ENSO LFC.  相似文献   

Evaluation of aluminum speciation in surface waters in China and its environmental risk assessment     

S.?P.?BiEmail author  N.?Gan  X.?C.?Lu  H.?Y.?Ni  H.?Lin  X.?L.?Wang  Z.?B.?Wei 《Environmental Geology》2003,45(1):65-71

As the ongoing global research on acid precipitation is developing in depth, more and more attention has been paid to the ecological effects of aluminum (Al) due to its toxicity to plants and animals, which is caused by acid precipitation. As a very serious problem of terrestrial and aquatic environmental acidification occurs in China, especially in southwestern China, a systematic investigation of Al speciation in these regions is very important. In this paper, the Al speciation results of surface waters in China are reported and its ecological impacts is evaluated. More than 100 water samples were collected from about twenty provinces of China. Driscoll's Al speciation scheme combined with the modified MINQEL computer model is used for speciation of Al. This study shows that the ecological impacts of acidification are quite different between China and Western countries, because of different geographical environments and geological settings. In Western countries, acidification is mainly caused by NO₂^-. Due to low concentrations of K⁺, Na⁺, Ca²⁺, Mg²⁺, the buffer capacities of soil and water are weak. Therefore, natural waters can be acidified to pH<5 very easily, resulting in a considerable mobilization of Al and worsening of the ecological environment. In China, acid precipitation is mainly in the form of sulfuric acid. In northwestern China, concentrations of K⁺, Na⁺, Ca²⁺, Mg²⁺ are high in soil and surface waters. This leads to much higher capacity and a high resistance ability to acidification. The pH values of waters in this region are high (around 7) and no serious Al toxicity is found at present. However, in northeastern and southeastern China, the soil is rich in Al (unsaturated aluminosilicates in northeastern China, saturated aluminosilicates in north and central China, aluminum-rich soil in southeastern and southwestern China). The concentrations of K⁺, Na⁺, Ca²⁺, Mg²⁺ in soil and waters are lower than those of northwestern China. Therefore the buffer capacity is limited. Numerous surface waters have already been acidified and pH values declined to 5. The impacts of Al toxicity on ecological systems in these regions are very serious, especially in Jiangxi, Hubei Provinces and Chongqing Municipality.  相似文献   

工业CT技术在卫星产品检测中的应用   总被引：2，自引：0，他引：2  

倪培君  李旭东  梁晓明  王爱华  孙守黑 《CT理论与应用研究》2000,9(Z1):119-123

卫星产品许多都采用了焊接结构。为了保证其使用的安全可靠性,必须对焊缝进行l00％的无损检测。然而对于一些形状复杂的精密电子束焊件,由于产品尺寸小,加之焊缝周围结构的遮挡,使常规方法的应用受到了限制。工业CT技术具有不受试件材料种类、形状结构及表面状况限制的特点,能给出与试件材料密度及尺寸特性相对应的断层扫描图象,分辨率高,在检测复杂构件方面显示出了优势。本文介绍了卫星产品精密复杂焊接件对无损检测技术的具体要求,研究了卫星产品电子束焊缝的工业CT检测方法,包括设备、对比试样、检测工艺、评定方法等,并通过电磁阀、喷注器、自锁阀、减压器、加注/排放阀、单向阀、气滤、过滤器等具体产品检测实例,描述了工业CT技术在卫星产品检测中的应用。实际应用表明：工业CT是检测航天卫星产品精密复杂结构件焊缝缺陷的理想手段,其成象直观,缺陷的定位、定性和定量结果可靠,完全能满足产品的质量控制要求。目前,累计用工业CT检测卫星产品数批若干件,检测焊缝上千条。剔出有超标缺陷的产品40件,避免了隐患。经过工业CT检测的产品,己在"返回式卫星"、"风云二号"、"东方红三号"、"资源一号"、"中星-22号"等型号卫星中取得了成功应用。  相似文献