念青唐古拉山脉西段雪线高度变化遥感观测

利用Landsat TM/ETM+/8 OLI和HJ1A遥感影像资料作为数据源,通过目视解译方法,提取念青唐古拉山脉西段雪线高度变化值,同时对研究区周边气温与降水变化趋势进行分析,研究其与冰川变化的关系。结果表明：2004~2013年北坡13条冰川和南坡15条冰川的雪线高度都呈升高的趋势;从整体上来考察,北坡雪线高度升高值为14 m/a,南坡升高值为4.9 m/a,北坡升高速度比南坡快;自1964年以来,研究区气温升高趋势显著,降水增加不明显,气候变暖是冰川退缩的主要原因;北坡冰川比南坡冰川经历更大的物质负平衡,主要是由于气温的升高率北坡比南坡快所致。     

Observed geomagnetic field intensity in London since 1820

Our main purpose is to collect all magnetic intensity data observed in the vicinity of London and to adjust these to a common site (Greenwich) to complement the 400-year series of declination ( D ) and inclination ( I ) data of Malin & Bullard (1981 ). The present series is necessarily shorter, since a method for the measurement of intensity in absolute units was not devised until 1832. We have also supplemented the D and I series of Malin & Bullard with recently acquired data.
We have also made observations of D , I and total intensity ( F ) at a number of the sites, partly to bring the series up to date and partly to check on the site differences. With the increasing urbanization of London it is necessary to seek data from remoter sites. It is shown that the site differences change significantly with time, but that allowance can be made for this.
We present curves of our best estimates of the variation of D , I , F and the horizontal intensity ( H ) that define the complete geomagnetic vector at Greenwich for the interval 1820–1998. Frequency analysis shows little support for a 60-year line in the power spectrum. Within the uncertainty of their determinations, there is good continuity between archaeomagnetic intensity measures and the present results. The moving eddy hypothesis of Malin & Bullard is found to be untenable.     

Palaeomagnetism of some Indian Rocks

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Hitherto, no palaeomagnetic data for India are available earlier than the Jurassic, 130 M.y. The remanent magnetic directions of oriented samples from one Jurassic and four pre-Cambrian rock formations in India have now been determined. One pre-Cambrian formation gave very scattered direction: the other four formations gave well-defined directions and their magnetic stability was demonstrated by a.c. and thermal demagnetization. The three pre-Cambrian results enable values of the ancient latitude and orientation of India to be estimated at 500, 600 and 750 M.y., assuming the ancient field to have been an axial dipole.
By making use of these new results, together with similar data by other workers for Australia, North America and Europe, it can be shown that, as far as the scanty data goes, the rate of drift in latitudes and orientation of the four continents has been of roughly the same magnitude throughout the period since 750 M.y.     

Observed climatic changes in Shanghai during 1873-2002

Variation characteristics of temperature and precipitation in January and July and annual mean temperature and annual precipitation are analyzed with the help of cumulative anomalies, Mann-Kendall analysis and wavelet analysis. The research results indicate that January precipitation presents an increasing trend after 1990, wavelet analysis result suggests that this increasing trend will continue in the near future. The changes of July precipitation present different features. During 1900-1960, July precipitation is in a rising trend, but is in a declining trend after 1960. Wavelet analysis shows that this declining trend will go on in the near future. Temperature variations in Shanghai are in fluctuations with 2 to 3 temperature rising periods. Mann-Kendall analysis indicates that temperature variations have the obvious abrupt change time when compared with precipitation changes in Shanghai during the past 100 years. The abrupt change time of January temperature lies in 1985, and that of July temperature lies in 1931-1933 and annual mean temperature has the abrupt change time in 1923-1930. Except July precipitation, the precipitation in January, temperature in January, July and annual mean temperature, and annual precipitation are also in a rising trend in the near future. The research results in this paper may be meaningful for future further climatic changes of Shanghai and social mitigation of climatic disasters in the future.     

Polarity Reversals and Oxidation State in Rocks

The correlation between reversed polarity in rocks and strong oxidation of magnetic minerals is briefly re-examined, with especial reference to a well-documented Columbia Plateau basalt suite, recently described in this journal. The correlation appears to vary in quality from place to place and some reasons for this are suggested. Attention is particularly drawn to recent studies which suggest that for palaeomagnetic purposes there may be two groups of lavas, divisible on the basis of whether their magnetic minerals became oxidized under high or low temperature conditions.
A sizable body of opinion now holds (not necessarily correctly) that self-reversals are a negligible factor in the correlation between oxidation and reversed polarity, and that some compositional effect is most probably involved. Virtually the only known petrographic criterion which can (statistically) distinguish reversely from normally magnetized rocks is their (statistically) higher oxidation states. An obvious implication is that the water content of magmas, and perhaps of high-grade metamorphic rocks, is somehow increased during episodes of reversed polarity, so that a slightly larger proportion of rocks is more strongly oxidized.
Since motions of the Earth's core, upper mantle processes, and field reversals are apparently all related, compositional changes originating in the upper mantle could well be also related to field reversals. Alternating linear zones of more and less altered baslat recently reported from one place near the mid-Atlantic ridge might have arisen in such a way.
The importance of relating palaeomagnetic measurements to detailed mineralogical studies of magnetic minerals is again stressed.     

中国西部冰川度日因子的空间变化特征

在冰川与积雪消融研究中,度日模型应用较为广泛,该模型是基于冰雪消融与气温,尤其是正积温之间的线性关系建立的。度日因子是该模型的重要参数,反映了单位正积温产生的冰雪消融量,其空间变化特征对于不同模型模拟冰雪消融过程的精度有较大影响。 本文根据中国西部不同地区数十条冰川的短期考察和观测资料,分析了西部冰川度日因子的空间变化特征,结果表明：由于青藏高原及其周围地区独特的气候和热量条件,西部冰川度日因子具有明显的区域特征。在同一冰川上,度日因子的空间变化较为明显。从冰川类型来看,与极大陆型及亚大陆型冰川相比,海洋型冰川的度日因子较大。总体看来,西部冰川的度日因子由西北向东南逐渐增大,这与中国西部冰川的气候环境变化趋势是一致的,即在干冷的气候条件下,度日因子较小;而在暖湿的气候条件下度日因子较大。     

1873-2005年上海干湿变化

Dryness and wetness variations on different time scales in Shanghai were analyzed using the Standardized Precipitation Index (SPI) based on monthly precipitation data for 1873-2005. The SPI on scales of 3, 6, 12 and 24 months has been calculated. The SPI on 3, 6, 12 and 24 months present 4 wet periods prevailed during 1873-1885, 1904-1923, 1938-1960 and 1983-2005, and 3 dry episodes during 1888-1903, 1924-1937 and 1961-1982. Significant periods of higher wavelet power in the SPI-24 months occurred on the time scales of 2-7-year band in around 1880-1890, 1910-1950 and 1970-1990, and at 8-15-year band in 1920-1960 and 1965-2000 respectively. Periodicities in the SOI and ENSO indices are similar to those in SPI-24 months with little difference, namely, in the SPI-24 months, there are significant periods at the 2-7- and 8-15-year bands during 1930-1940. The periodicity components in individual SPI-24 months, SOI and ENSO indices are more complicated, showing the wetness and dryness variability in Shanghai is controlled by more than one physical factors. The research results indicate that the Shanghai area has experienced dryness and wetness variability on different time scales during the past 133 years.     

基于GIS的定位观测数据空间化

属性数据空间化是当前GIS领域的前沿问题之一。在对中国624个气象站多年平均气温数据空间化过程中,通过使用30秒分辨率的数字高程数据,把气温分解为受经纬度、海拔高度影响的规律性成分和受其它因素影响的非规律性成分两部分,并分别用多元回归和反距离权重内插方法对二者实施空间化,最后将空间化结果进行合成得到基于栅格的中国多年平均气温分布数据。该数据既能反映气温在空间上的宏观变化,又能反映气温在局部地区的微观变化。该方法可供其它类型观测数据空间化、特别是在观测站点稀疏的情况下参考和借鉴。     

中文文本中时间信息解析方法

探讨了基于触发词汇和规则模型相结合的中文文本中时间信息解析方法。通过分析、归纳中文文本中时间信息描述特点,构建时间词汇词典和时间信息描述模式库,设计时间信息抽取、规范化表达和语义推理算法,实现了中文文本中时间信息的解析。实验结果表明,中文文本中时间信息抽取的准确率、召回率和F1值分别为75.00%、88.24%和40.54%,为泛在时空信息动态关联更新和实时挖掘分析提供数据源,且通过与空间维数据有机地、交互地组织,能够实时展现地理现象和事物的时空演化过程、时空分布特征,从而推动地理信息检索、LBS等地理信息服务向动态化、多维化方向发展。