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81.
Geostatistical analysis of soil moisture measurements and remotely sensed data at different spatial scales 总被引:1,自引:0,他引:1
The European remote sensing satellite (ERS-2) synthetic aperture radar (SAR) data was used for temporal monitoring of soil moisture at Sukhothai, Thailand. Higher correlations were found between the observed soil moisture and the radar backscattering coefficient. The soil moisture distribution shows great variation in space and time due to its stochastic nature. In order to obtain a better understanding of the nature and causes of spatial variation of soil moisture, the extensive soil moisture measurements observed in Thailand and also remotely sensed ERS-2 SAR data were used for geostatistical analysis. The observed soil moisture shows seasonal variations with mean varying from 3.33 %v/v (dry season) to 33.44 %v/v (wet season). The spatial geostatistical structure also shows clear seasonal variations in the geostatistical characteristics such as range and sill. The sills vary from 1.00 (%v/v)2 for the driest day to 107.57 (%v/v)2 for one of the wet days. The range or the correlation lengths varies between 46.5 and 149.8 m for the wettest and driest periods. The nugget effect does not show strong seasonal pattern or trend but the dry periods usually have a smaller nugget effect than the wet periods. The spherical variogram model fits the sample variograms very well in the case of soil moisture observations while the exponential model fits those of the remotely sensed data. The ranges observed from the observed soil moisture data and remotely sensed data at the same resolution are very similar. Resolution degradation affects the geostatistical structure of the data by reducing the sills, and increasing the ranges. 相似文献
82.
Yawar?HussainEmail author Frédéric?Satgé Muhammad?Babar?Hussain Hernan?Martinez-Carvajal Marie-Paule?Bonnet Martin?Cárdenas-Soto Henrique?Llacer?Roig Gulraiz?Akhter 《Theoretical and Applied Climatology》2018,131(3-4):1119-1132
The present study aims at the assessment of six satellite rainfall estimates (SREs) in Pakistan. For each assessed products, both real-time (RT) and post adjusted (Adj) versions are considered to highlight their potential benefits in the rainfall estimation at annual, monthly, and daily temporal scales. Three geomorphological climatic zones, i.e., plain, mountainous, and glacial are taken under considerations for the determination of relative potentials of these SREs over Pakistan at global and regional scales. All SREs, in general, have well captured the annual north-south rainfall decreasing patterns and rainfall amounts over the typical arid regions of the country. Regarding the zonal approach, the performance of all SREs has remained good over mountainous region comparative to arid regions. This poor performance in accurate rainfall estimation of all the six SREs over arid regions has made their use questionable in these regions. Over glacier region, all SREs have highly overestimated the rainfall. One possible cause of this overestimation may be due to the low surface temperature and radiation absorption over snow and ice cover, resulting in their misidentification with rainy clouds as daily false alarm ratio has increased from mountainous to glacial regions. Among RT products, CMORPH-RT is the most biased product. The Bias was almost removed on CMORPH-Adj thanks to the gauge adjustment. On a general way, all Adj versions outperformed their respective RT versions at all considered temporal scales and have confirmed the positive effects of gauge adjustment. CMORPH-Adj and TMPA-Adj have shown the best agreement with in situ data in terms of Bias, RMSE, and CC over the entire study area. 相似文献
83.
Limnological effects of growth and cessation of agricultural land use in Ladoga Karelia: sedimentary pollen and diatom analyses 总被引:2,自引:0,他引:2
Juha O.?MiettinenEmail author Heikki?Simola Elisabeth?Gr?nlund Jaana?Lahtinen Riitta?Niinioja 《Journal of Paleolimnology》2005,34(2):229-243
Reference conditions and changes in limnological conditions during the 20th century have been inferred in a palaeolimnological study of sediments from six lakes of the District of Sortavala, Karelian Republic, Russia. The area is former Finnish territory, which was in intensive use for arable field cultivation until the World War II, when the area was ceded to the Soviet Union. After the war, farming was resumed by cattle sovkhozes, and the fields were mainly used as pasture without regular ploughing. We have studied the history of eutrophication and recovery in some lakes related with the changes of agricultural intensity. The trophic level of the lakes was studied by sedimentary diatom assemblages, including reconstructions of total phosphorus levels in the lakes based on a weighted averaging transfer function. Pollen analyses were used to assess the changes in the land use near the lakes. Valuable background data on all the lakes used in the present study are provided by a doctoral thesis done on their limnology from the 1920s. According to our results, the four lakes situated on the clayey lowlands near the coast of Lake Ladoga were eutrophicating during the first half of the 20th century, and in two of them, a rapid recovery is evident. In two lakes situated in hilly landscape with limited agricultural activities, only minor changes are recorded in the diatom profiles. 相似文献
84.
Christine?MillerEmail author Roland?Mundil Martin?Th?ni Jürgen?Konzett 《Contributions to Mineralogy and Petrology》2005,150(1):70-84
High-pressure metamorphism in the Pohorje Mountains of Slovenia (Austroalpine unit, Eastern Alps) affected N-MORB type metabasic
and metapelitic lithologies. Thermodynamic calculations and equilibrium phase diagrams of kyanite–phengite-bearing eclogites
reveal PT conditions of >2.1 GPa at T<750°C, but within the stability field of quartz. Metapelitic eclogite country rocks contain the assemblage garnet + phengite
+ kyanite + quartz, for which calculated peak pressure conditions are in good agreement with results obtained from eclogite
samples. The eclogites contain a single population of spherical zircon with a low Th/U ratio. Combined constraints on the
age of metamorphism come from U/Pb zircon as well as garnet–whole rock and mineral–mineral Sm-Nd analyses from eclogites.
A coherent cluster of single zircon analyses yields a 206Pb/238U age of 90.7±1.0 Ma that is in good agreement with results from Sm-Nd garnet–whole rock regression of 90.7±3.9 and 90.1±2.0 Ma
(εNd: +8) for two eclogite samples. The agreement between U-Pb and Sm-Nd age data strongly suggests an age of approximately
90 Ma for the pressure peak of the eclogites in the Pohorje Mountains. The presence of garnet, omphacite and quartz inclusions
in unfractured zircon indicates high-pressure rather than ultrahigh pressure conditions. The analysed metapelite sample yields
a Sm-Nd garnet–whole rock scatterchron age of 97±15 Ma. These data probably support a single P-T loop for mafic and pelitic
lithologies of the Pohorje area and a late Cretaceous high-pressure event that affected the entire easternmost Austroalpine
basement including the Koralpe and Saualpe eclogite type locality in the course of the complex collision of the Apulian microplate
and Europe. 相似文献
85.
Emplacement of a giant submarine slide complex, offshore of South Kona, Hawaii Island, was investigated in 2001 by visual observation and in-situ sampling on the bench scarp and a megablock, during two dives utilizing the Remotely Operated Vehicle (ROV) Kaiko and its mother ship R/V Kairei. Topography of the bench scarp and megablocks were defined in 3-D perspective, using high-resolution digital bathymetric data acquired during the cruise. Compositions of 34 rock samples provide constraints on the landslide source regions and emplacement mechanisms. The bench scarp consists mainly of highly fractured, vesiculated, and oxidized aa lavas that slumped from the subaerial flank of ancestral Mauna Loa. The megablock contains three units: block facies, matrix facies, and draped sediment. The block facies contains hyaloclastite interbedded with massive lava, which slid from the shallow submarine flank of ancestral Mauna Loa, as indicated by glassy groundmass of the hyaloclastite, low oxidation state, and low sulfur content. The matrix facies, which directly overlies the block facies and is similar to a lahar deposit, is thought to have been deposited from the water column immediately after the South Kona slide event. The draped sediment is a thin high-density turbidite layer that may be a distal facies of the Alika-2 debris-avalanche deposit; its composition overlaps with rocks from subaerial Mauna Loa. The deposits generated by the South Kona slide vary from debris avalanche deposit to turbidite. Spatial distribution of the deposits is consistent with deposits related to large landslides adjacent to other Hawaiian volcanoes and the Canary Islands. 相似文献
86.
87.
Large-scale European atmospheric circulation induced by temperature differences between the continent and the North Atlantic Ocean causes thermodynamic and climatic conditions that initiate a European monsoon. In Eastern Europe, the rainy season occurs in early summer, and the dry season occurs in winter. In Western Europe, the rainy season is in the early winter and the dry season is in the spring. This precipitation trend, as well as other climatic features, suggests the existence of a European monsoon. 相似文献
88.
对发震构造呈复杂几何关系(发震构造在平面投影呈非平行关系)下彼此发震影响的机理进行了研究.从发震的“垂震底继”影响关系研究了1933年迭溪地震M7.5和1976年松潘Ms7.2地震对后来发生汶川M8地震的龙门山地震构造的孕震能量叠加的加震作用;同时也指出汶川8级地震对周边断裂的减震作用,计算并指出了其影响减震的距离.研究对CPSHA中对发震构造呈复杂几何关系时,如何确定地震带内各潜在的震源空间分布函数fi,mj提供了大震加减震的判断理论依据.还讨论了汶川地震孕震模式的更复杂性,针对某些用巴颜喀拉块体向东南方向移动挤压龙门山孕震构造,进而解释汶川地震的逆冲性所带来的矛盾的观点,对其孕震的复杂性提出了问题所在和初步探讨. 相似文献
89.
90.
Martina?S?tteleEmail author Michael?Krautblatter Michael?Bründl Daniel?Straub 《Landslides》2016,13(4):737-750
Warning systems are increasingly applied to reduce damage caused by different magnitudes of rockslides and rockfalls. In an integrated risk-management approach, the optimal risk mitigation strategy is identified by comparing the achieved effectiveness and cost; estimating the reliability of the warning system is the basis for such considerations. Here, we calculate the reliability and effectiveness of the warning system installed in Preonzo prior to a major rockfall in May 2012. “Reliability” is defined as the ability of the warning system to forecast the hazard event and to prevent damage. To be cost-effective, the warning system should forecast an event with a limited number of false alarms to avoid unnecessary costs for intervention measures. The analysis shows that to be reliable, warning systems should be designed as fail-safe constructions. They should incorporate components with low failure probabilities, high redundancy, have low warning thresholds, and additional control systems. In addition, the experts operating the warning system should have limited risk tolerance. In an additional hypothetical probabilistic analysis, we investigate the effect of the risk attitude of the decision makers and of the number of sensors on the probability of detecting the event and initiating a timely evacuation, as well as on the related intervention cost. The analysis demonstrates that quantitative assessments can support the identification of optimal warning system designs and decision criteria. 相似文献