非合作目标分光路激光测距中距离值的确定方法     

李语强  李荣旺  李祝莲  翟东升 《云南天文台台刊》2012,(2):137-142

摘要：卫星激光测距是目前空间大地测量的主要手段之一,在地球动力学和大地测量学等领域有广泛的应用。云南天文台即将开展非合作目标分光路激光测距试验,即激光接收和发射光路系统分别由相邻较近的两台望远镜完成。针对分光路非合作目标激光测距系统,提出了一种非合作目标分光路激光测距中测距值的确定方法,并给出了相应的计算公式,为分光路激光测距数据处理提供参考。  相似文献   

Using Neural Nets to Model the Spatial Distribution of Seasonal Homes     

《制图学和地理信息科学》2013,40(3):281-290

Seasonal and second homes are important aspects of recreational tourism. Owning a summer cottage, time-share condominium, hunting cabin, or a part-time residence in a location away from home affects development patterns in significant ways. This paper presents the results of using an artificial neural network and a geographic information systems-based approach to identify and quantify the principal predictors of seasonal home distribution within the Lake States region of Minnesota, Wisconsin, and Michigan. Representative variables, such as proximity and spatial configuration of lakes, proximity to the Great Lakes shore, surrounding forest acreage, and public land access have been quantified using geographic information systems at the minor civil division (MCD) scale for the three states. The GIS data have then been fed into artificial neural networks to enable these pattern recognition tools to identify the principal predictors of seasonal home distribution in the Upper Great Lakes States.  相似文献   

Analysis of aftershock sequences in South and Southeastern Spain     

《Physics and Chemistry of the Earth》2013

A probabilistic modeling is used to analyze the spatio-temporal behavior of eleven aftershock sequences occurred in South and Southeastern Spain. This study focuses on the analysis of two seismicity parameters: the b-value of the frequency-magnitude distribution, and the p-value, explaining the temporal decay rate of aftershocks. The estimated b values range between 0.77 ± 0.05 and 1.18 ± 0.10 close to the typical b-values of the aftershock frequency-magnitude relationship b ≈ 1.0. The estimated p-values range between 0.75 ± 0.03 and 1.43 ± 0.10 showing broad regimes of the temporal decay of aftershocks. The modified Bath’s law used to analyze the energy partitioning, suggests that a large fraction of the accumulated energy is released in the mainshock and relatively small fraction of energy is released during aftershock sequence, for example 80% of the total energy is released during the Mula 1999 mainshock, 88% during Bullas 2002 mainshock and 87% during La Paca 2005 mainshock. The fractal dimension D₂ is estimated using the correlation integral, and then used to derive the slip ratio, as the ratio of the slip occurred on primary fault segment to the total slip. For example, we obtained a slip ratio equal to 71% for the Mula 1999 aftershock sequence, 61% for the Bullas 2002 event, 58% for the La Paca 2005 aftershock, 50% for the Lorca 2011 sequence and 63% for the sequence triggered by the Gador 2002 mainshock.Finally, the correlations between the fractal dimension, the b-value and the p-value is analyzed, and the Aki’s relation D = 3b/c is discussed as well.  相似文献   

Encyclopedia of the Great Plains     

《The Professional geographer》2013,65(2):328-329

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INFLUENCE OF SUBARCTIC VEGETATION COVER ON SNOWMELT     

J. E. FitzGibbon  T. Dunne 《自然地理学》2013,34(1):61-70

An examination of the three major components of the energy balance has shown that subarctic vegetation cover markedly alters the relative importance of these components for the snowmelt. It has been found that the contribution of net radiation decreases as forest cover decreases while sensible and latent heat contributions to the snowmelt increase with decreasing forest cover. The decrease in the importance of net radiation with decreasing forest cover is due to the effect of the forest cover on albedo and the effects of the forest cover on the long-wave radiation component of the radiation balance. This situation seems to be typical for open canopy forests. The increase in importance of sensible and latent heat in the open is due to the increase in wind speed from the forest to open sites.  相似文献   

Synoptic Classification of Snowfall Events in the Great Smoky Mountains,USA     

《自然地理学》2013,34(2):156-171

Mean annual snowfall in the Great Smoky Mountains National Park (GSMNP) exhibits considerable spatial variability, ranging from 30 cm in the valleys to 254 cm at higher elevations. Snowfall can be tied to a variety of synoptic classes (e.g., Miller A or B cyclones, 500 hPa cutoff lows), but the frequency and significance of different synoptic classes have not been fully assessed, particularly at higher elevations. In this paper, we manually classify all snowfall events during the period 1991 to 2004 according to a synoptic classification scheme, calculate mean annual snowfall by 850 hPa wind direction and synoptic class, and develop composite plots of various synoptic fields. Hourly observations from nearby first-order stations and 24 hr snowfall totals from five sites within the GSMNP are used to define snowfall events. NCEP/NCAR reanalysis data are used to develop composite plots of various synoptic fields for cyclones passing south and then east of the area (e.g., Miller A cyclones). Results indicate that over 50% of the mean annual snowfall at higher elevations occurs in association with low-level northwest flow, and that Miller A cyclones contribute the greatest amount to mean annual snowfall at all elevations.  相似文献   

南大洋普里兹湾沉积物中锗的含量与分布   总被引：1，自引：0，他引：1       下载免费PDF全文

沈忱  扈传昱  孙维萍  张海生 《极地研究》2013,25(2):105-112

本文利用中国第21-27次南极考察期间获得的沉积物样品,对南大洋普里兹湾沉积物中锗（Ge）的含量以及分布特征进行了初步研究。结果表明：普里兹湾表层沉积物中总Ge（Getotal）的含量在1.14×10-6~2.35×10-6之间变化,平均含量为1.71×10-6,最高值出现在湾外深海区P3-9站,最低值出现在湾内冰架边缘附近的P4-13站。在研究海域表层沉积物中生源Ge（Gebio）占Getotal的百分含量在16-68%之间变化。在表层沉积物中Gebio与Getotal分布变化趋势总体上相近,以67°S为界均呈现湾外高于湾内的趋势,在柱状沉积物中Ge的垂向分布呈现表层高于底层趋势。在普里兹湾湾内非冰间湖区域的表层沉积物中Gebio与生物硅（BSiO2）呈现一定的正相关,在P3-16站位柱状沉积物中Gebio与BSiO2垂向分布相似。  相似文献   

Identifying spatial concentrations of surnames     

James A. Cheshire 《International journal of geographical information science》2013,27(2):309-325

Surnames (family names) have been overlooked as a valuable source of spatially referenced population data. Presented here is a methodology, based on kernel density estimation, which is used to identify the areas of Great Britain where any surname is most concentrated. This not only indicates a surname's geographic origin in the country but also its current spatial extent and spatial relationship with other surnames and place names. We argue that such analysis can provide baseline and change measures, and an empirical basis to change forecasting. Such analysis offers valuable insights into national, regional and local changes in population structure, and testimony to the relevance of GIScience to population genetics, historical geography and genealogy.  相似文献   

Satellite Monitoring of the Biomass Production in Southern Greenland     

Birger Ulf Hansen M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):94-99

Birger Ulf Hansen: Satellite Monitoring of the Biomass Production in Southern Greenland. Geografisk Tidsskrift 88:94–99. Copenhagen, 1988.

Based on satellite data from Southern Greenland the application of Normalized Difference Vegetation Index (NDVI) for monitoring biomass production has been evaluated. Field measurements of spectral reflectance data are quantitatively correlated with clipped samples of total above-ground biomass production. The relation between NDVI measured on the ground and biomass production is discussed. The seasonal and geographical variation in NDVI is correlated with the climate and water balance. The potential production is estimated as the product of mean NDVI and the length of the growing season. The results suggest that operational satellite monitoring of NDVI provides valuable assistance in agricultural management and forward planning of the potential breeding capacity in an arctic/subarctic environment.  相似文献   

Changing Properties of Snowpack in the Great Salt Lake Basin,Western United States,from a 26-Year SNOTEL Record   总被引：1，自引：1，他引：0  

Daniel Bedford  Andrea Douglass 《The Professional geographer》2013,65(3):374-386

Daily observations from automated snowpack telemetry (SNOTEL) stations from within the drainage basin of the Great Salt Lake over the period from 1982 to 2007 are analyzed. The major finding is a shift toward an earlier date of peak snow water equivalent (SWE) by around fifteen days. Less robust findings are reductions in the amounts of peak SWE and 1 April SWE. This suggests increased chances of late-summer water shortages, especially when combined with rapid recent population growth. Less freshwater is likely to be available to flow into the Great Salt Lake, increasing its salinity and potentially affecting its ecology.  相似文献