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1.
Weiguang Wang Quanxi Shao Shizhang Peng Zengxin Zhang Wanqiu Xing Guiyang An Bin Yong 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(7):881-895
The present study explores the spatial and temporal changing patterns of the precipitation in the Haihe River basin of North
China during 1957–2007 at annual, seasonal and monthly scales. The Mann–Kendall and Sen’s T tests are employed to detect the trends, and the segmented regression is applied to investigate possible change points. Meanwhile,
Sen’s slope estimator is computed to represent the magnitudes of the temporal trends. The regional precipitation trends are
also discussed based on the regional index series of four sub-basins in the basin. Serial correlation of the precipitation
series is checked prior to the application of the statistical test to ensure the validity of trend detection. Moreover, moisture
flux variations based on the NCEP/NCAR reanalysis dataset are investigated to further reveal the possible causes behind the
changes in precipitation. The results show that: (1) Although the directions of annual precipitation trends at all stations
are downward, only seven stations have significant trends at the 90% confidence level, and these stations are mainly located
in the western and southeastern Haihe River basin. (2) Summer is the only season showing a strong downward trend. For the
monthly series, significant decreasing trends are mainly found during July, August and November, while significant increasing
trends are mostly observed during May and December. In comparison with the annual series, more intensive changes can be found
in the monthly series, which may indicate a shift in the precipitation regime. (3) Most shifts from increasing trends to decreasing
trends occurred in May–June, July, August and December series, while opposed shifts mainly occurred in November. Summer is
the only season displaying strong shift trends and the change points mostly emerged during the late 1970s to early 1980s.
(4) An obvious decrease in moisture flux is observed after 1980 in comparison with the observations before 1980. The results
of similar changing patterns between monthly moisture budget and precipitation confirmed that large-scale atmospheric circulation
may be responsible for the shift in the annual cycle of precipitation in the Haihe River basin. These findings are expected
to contribute to providing more accurate results of regional changing precipitation patterns and understanding the underlying
linkages between climate change and alterations of hydrological cycles in the Haihe River basin. 相似文献
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We investigate the transient response of the global coupled ocean?Catmosphere system to enhanced freshwater forcing representative of melting of the Greenland ice sheets. A 50-year long simulation by a coupled atmosphere?Cocean general circulation model (CGCM) is compared with another of the same length in which Greenland melting is prescribed. To highlight the importance of coupled atmosphere?Cocean processes, the CGCM results are compared with those of two other experiments carried out with the oceanic general circulation model (OGCM). In one of these OGCM experiments, the prescribed surface fluxes of heat, momentum and freshwater correspond to the unperturbed simulation by the CGCM; in the other experiment, Greenland melting is added to the freshwater flux. The responses by the CGCM and OGCM to the Greenland melting have similar patterns in the Atlantic, albeit the former having five times larger amplitudes in sea surface height anomalies. The CGCM shows likewise stronger variability in all state variables in all ocean basins because the impact of Greenland melting is quickly communicated to all ocean basins via atmospheric bridges. We conclude that the response of the global climate to Greenland ice melting is highly dependent on coupled atmosphere?Cocean processes. These lead to reduced latent heat flux into the atmosphere and an associated increase in net freshwater flux into the ocean, especially in the subpolar North Atlantic. The combined result is a stronger response of the coupled system to Greenland ice sheet melting. 相似文献
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Hristos Tyralis Demetris Koutsoyiannis 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(1):21-33
Various methods for estimating the self-similarity parameter (Hurst parameter, H) of a Hurst–Kolmogorov stochastic process (HKp) from a time series are available. Most of them rely on some asymptotic properties
of processes with Hurst–Kolmogorov behaviour and only estimate the self-similarity parameter. Here we show that the estimation
of the Hurst parameter affects the estimation of the standard deviation, a fact that was not given appropriate attention in
the literature. We propose the least squares based on variance estimator, and we investigate numerically its performance,
which we compare to the least squares based on standard deviation estimator, as well as the maximum likelihood estimator after
appropriate streamlining of the latter. These three estimators rely on the structure of the HKp and estimate simultaneously
its Hurst parameter and standard deviation. In addition, we test the performance of the three methods for a range of sample
sizes and H values, through a simulation study and we compare it with other estimators of the literature. 相似文献
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K. Mallika Harsh Gupta D. Shashidhar N. Purnachandra Rao Amrita Yadav Sunil Rohilla H. V. S. Satyanarayana D. Srinagesh 《Journal of Seismology》2013,17(1):189-195
It is generally found that the b values associated with reservoir-triggered seismicity (RTS) are higher than the regional b values in the frequency magnitude relation of earthquakes. In the present study, temporal and spatial variation of b value is investigated using a catalog of 3,000 earthquakes from August 2005 through December 2010 for the Koyna?CWarna region in Western India, which is a classical site of RTS globally. It is an isolated (30?×?20?km2) zone of seismicity where earthquakes of up to M ??5 are found to occur during phases of loading and unloading of the Koyna and Warna reservoirs situated 25?km apart. For the Warna region, it is found that low b values of 0.6?C0.9 are associated with earthquakes of M ??4 during the loading phase. The percentage correlation of the occurrence of an M????4 earthquake with a low b value outside the 1?? or 2?? level is as high as 78?%. A drastic drop in the b value of about 50?% being reported for an RTS site may be an important precursory parameter for short-term earthquake forecast in the future. 相似文献
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In this study, a new estimate of the contribution of glaciers and ice caps to the sea-level rise over the period 1800?C2005 is presented. We exploit the available information on changes in glacier length. Length records form the only direct evidence of glacier change that has potential global coverage before 1950. We calculate a globally representative signal from 349 glacier length records. By means of scaling, we deduce a global glacier volume signal, that is calibrated on the mass-balance and geodetic observations of the period 1950?C2005. We find that the glacier contribution to sea-level rise was 8.4 ± 2.1 cm for the period 1800?C2005 and 9.1 ± 2.3 cm for the period 1850?C2005. 相似文献
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Mass balance estimates for the Antarctic Ice Sheet (AIS) in the 2007 report by the Intergovernmental Panel on Climate Change and in more recent reports lie between approximately +50 to ?250 Gt/year for 1992 to 2009. The 300 Gt/year range is approximately 15% of the annual mass input and 0.8 mm/year Sea Level Equivalent (SLE). Two estimates from radar altimeter measurements of elevation change by European Remote-sensing Satellites (ERS) (+28 and ?31 Gt/year) lie in the upper part, whereas estimates from the Input-minus-Output Method (IOM) and the Gravity Recovery and Climate Experiment (GRACE) lie in the lower part (?40 to ?246 Gt/year). We compare the various estimates, discuss the methodology used, and critically assess the results. We also modify the IOM estimate using (1) an alternate extrapolation to estimate the discharge from the non-observed 15% of the periphery, and (2) substitution of input from a field data compilation for input from an atmospheric model in 6% of area. The modified IOM estimate reduces the loss from 136 Gt/year to 13 Gt/year. Two ERS-based estimates, the modified IOM, and a GRACE-based estimate for observations within 1992?C2005 lie in a narrowed range of +27 to ?40 Gt/year, which is about 3% of the annual mass input and only 0.2 mm/year SLE. Our preferred estimate for 1992?C2001 is ?47 Gt/year for West Antarctica, +16 Gt/year for East Antarctica, and ?31 Gt/year overall (+0.1 mm/year SLE), not including part of the Antarctic Peninsula (1.07% of the AIS area). Although recent reports of large and increasing rates of mass loss with time from GRACE-based studies cite agreement with IOM results, our evaluation does not support that conclusion. 相似文献
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总结回顾了江苏二十多年来的防震减灾工作,分析了当前搞好防震减灾工作的形势,从７个方面阐述了要抓住机遇,依法行政提高全省防震减灾工作水平的有关问题。 相似文献
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梅岭,又名大庾岭,为南岭山系五岭之首。梅关是粤赣交界的险关要塞,素有“岭南第一关”之誉,秦汉以前已存在。梅岭以梅花著称。古道与关同时出现,到唐初张九龄扩展岭路成坦途。 相似文献
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Ｔｈｅｆａｕｌｔｐｌａｎｅｏｆｔｈｅ１９９１，Ｄａｔｏｎｇ－Ｙａｎｇ－ｇａｏ，Ｓｈａｎｘｉ，Ｃｈｉｎａ，Ｍｓ＝５．８ｅａｒｔｈｑｕａｋｅＭｉｎｇＷＡＮＧ（王鸣），Ｌｉａｎ－ＱｉａｎｇＺＨＡＮＧ（张廉强）ａｎｄＰｅｉ－ＤｅＷＡＮＧ（王培德）（Ｉｎｓｔｉ... 相似文献
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Olga Sarychikhina Ewa Glowacka Braulio Robles F. Alejandro Nava Miguel Guzmán 《Pure and Applied Geophysics》2015,172(11):3139-3162
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Michelle M. Selvans Joann M. Stock Charles DeMets Osvaldo Sanchez Bertha Marquez-Azua 《Pure and Applied Geophysics》2011,168(8-9):1435-1447
A GPS campaign network in the state of Jalisco was occupied for?~36?h per station most years between 1995 and 2005; we use data from 1998?C2001 to investigate tectonic motion and interseismic deformation in the Jalisco area with respect to the North America plate. The twelve stations used in this analysis provide coverage of the Jalisco Block and adjacent North America plate, and show a pattern of motion that implies some contribution to Jalisco Block boundary deformation from both tectonic motion and interseismic deformation due to the offshore 1995 earthquake. The consistent direction and magnitude of station motion on the Jalisco Block with respect to the North America reference frame,?~2?mm/year to the southwest (95% confidence level), perhaps can be attributed to tectonic motion. However, some station velocities within and across the boundaries of the Jalisco Block are also non-zero (95% confidence level), and the overall pattern of station velocities indicates both viscoelastic response to the 1995 earthquake and partial coupling of the subduction interface (together termed ??interseismic deformation??). Our results show motion across the northern Colima rift, the eastern boundary of the Jalisco Block, which is likely to be sinistral oblique extension rather than pure extension. We constrain extension across both the Colima rift and the northeastern boundary of the Jalisco Block, the Tepic-Zacoalco rift, to???8?mm/year (95% confidence level), slow compared to relative rates of motion at nearby plate boundaries. 相似文献
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Introduction The June 4, 2000 southern Sumatra, Indonesia, earthquake (16h28min26.2s UTC, 4.72, 102.09, 33 km, MS=8.0 [IRIS]) occurred under the Indian Ocean, near the Mentawai fault, along the well-known Sumatran subduction zone and the great Sumatran fault, all of which trend northwest-southeast. 1 800 houses were totally destroyed, 10 196 were heavily damaged, and 18 378 were slightly damaged by the earthquake. At least 97 people were killed, 1 900 were injured, and 122 000 were left… 相似文献
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多种岩石的Qp,Qs,Qc 总被引：2，自引：0，他引：2
本采用脉冲传播谱振幅比法、能量法、尾波法分别测多种岩样的Ｐ波Ｑ值、Ｓ波Ｑ值及尾波Ｑ值。结果表明，能量法所得Ｑｐ、Ｑｓ较小。谱振幅比法所得Ｑｐ一般居中，Ｑｓ较大。尾波Ｑｃ有的偏大，有的偏小。 相似文献
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《Astronomy& Geophysics》2009,50(2):2.10-2.11
Professional astronomy operates in a world of big-budget, complex instruments, competition for observing time, and publishing deadlines. Sue Bowler asks how amateur astronomers fit into this world – if at all. 相似文献