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气候变化对内蒙古小叶杨叶芽开放期的影响 总被引：5，自引：0，他引：5
利用趋势倾向率等统计分析方法,对内蒙古气候(1961—2006年)和小叶杨叶芽开放期(1981—2006年)的变化趋势进行了分析,并探讨小叶杨叶芽开放期与不同时段的气温、降水、日照的相关性以及气候因子的综合作用。分析发现:内蒙古地区小叶杨叶芽开放期变化趋势表现出强烈的地域差异。小叶杨平均叶芽开放期孪井滩最早,鄂温克最晚,两地相差39 d;各地区小叶杨叶芽开放期的变化趋势基本一致,除额尔古纳呈提前趋势外,其他地区表现出延迟趋势;小叶杨叶芽开放期与春季气温均呈显著负相关,即春季气温升高,小叶杨叶芽开放期提前,与降水和日照的相关性不显著;在日照充足的内蒙古地区气温和降水共同影响着小叶杨叶芽开放期的变化。 相似文献
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Three time series based on precisely dated annual tree-ring widths have been used to reconstruct June plus July degree days for the central Alaska and northwestern Canada region. The time series are the longest recently developed chronologies for the area and represent 57 core samples from 27 trees. The degree-day reconstruction, extending back to A.D. 1524, exhibits much year-to-year variation and extended warming and cooling trends including a general warming trend from about 1840 to 1960. The reconstruction is in agreement with some subaretic glacial information and with data of percentage melting from arctic ice cores. This and similar reconstructions can provide quantitative information to compare with general circulation and energy budget models for longer time periods than are available in recorded meteorological data. 相似文献
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Marco Pilz Stefano Parolai Dino Bindi Annamaria Saponaro Ulan Abdybachaev 《Pure and Applied Geophysics》2014,171(8):1729-1745
A strong topographic relief and the presence of weakly consolidated sediments create favorable conditions for the development of landslides around the eastern rim of the Fergana Basin (Central Asia). In summer 2012, a field experiment employing small aperture seismic arrays was carried out on an unstable slope, using ambient vibration recordings. The aim of the study was to constrain the seismic response of a potential future landslide and to map lateral and vertical changes in the shear-wave velocity of the surficial soil layers. Strong variations of horizontal-to-vertical spectral ratios in terms of amplitude and directionality indicated clear differences in local site effects, probably reflecting the stability of different sections of the slope. Results further showed resonant frequencies of both the entire unstable block, as well as for smaller, individual parts. The use of an ad hoc, passive seismic tomography approach based on noise correlograms allowed for the mapping of the shear-wave velocities of the sliding material, even in cases of significant topography relief. Based on the recording of seismic noise only, we clearly identified a low-velocity body of weakly consolidated claystone and limestone material, which can be interpreted as the landslide body, with laterally varying thickness. 相似文献
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Coco M. Rulinda Alfred Stein Ulan D. Turdukulov 《International journal of geographical information science》2013,27(8):1481-1496
Remote-sensing-based drought monitoring methods provide fast and useful information for a sustainable management strategy of drought impact over a region. Common pixel-based monitoring methods are limited in the analysis of the dynamics of this impact at regional scale. For instance, these hardly allow us to quantify the movement of drought in space and time and to compare drought with rainfall deficits without losing the variability of these events within a region. This study proposed an object-based approach that allowed us to visualize and quantify the spatio-temporal movement of drought impact on vegetation, called vegetative drought, in a region. The GIS software Dynomap was used to extract and track objects. Measures of distance and angle were used for determining the speed and direction of vegetative drought and rainfall deficit objects, calculated from the National Oceanic and Atmospheric Administration's (NOAA's) normalized difference vegetation index and rainfall estimates data. The methods were applied to the two rainy seasons during the drought year 1999 in East Africa. Results showed that vegetative drought objects moved into the southwestern direction at an average angle of??138.5° during the first season and??144.5° during the second season. The speed of objects varied between 38 km dekad?1 and 185 km dekad?1 during the first season and between 33 km dekad?1 and 144 km dekad?1 during the second season, reflecting the rate of spread between dekads. Vegetative drought objects close to rainfall deficit objects showed similar trajectories and sometimes regions overlapped. This indicated that the two events are related. We conclude that a spatiotemporal relationship existed between the two types of events and that this could be quantified. 相似文献
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