Venus is similar to the Earth in size, mass, composition and distance to the sun. However, Venus has neither plate tectonics nor dynamo that exists on the Earth. The lithosphere of Venus is very thick based on its topography and gravity. The admittance and correlation between Venusian geoid and topography are very high, suggesting that they are strongly influenced by the internal dynamical process of Venus. Analyses show that there may be 10 Hawaii-like mantle plumes in Venusian mantle. Data from Venus Express has shown evidence for recent active volcanism among several of these plumes. The distribution of impact craters on Venus shows that Venusian surface has a young age and the age is averaged about 500 Ma, suggesting that Venus may have experienced a global resurfacing event. However, whether this resurfacing is catastrophic or equilibrium is still under debate. It is also unclear whether Venus had plate tectonics in the past, is it always in stagnant lid regime, or might it have an entirely different mode?In general, the style of mantle convection on Venus is quite different from that of the Earth which is manifested by the plate tectonics. Here we reviewed the main observations including gravity, topography and surface tectonics which provide constrains on the interior structure and dynamics of Venus, and recent advance in the interior structure and dynamics of Venus. This review aims to provide new insights into the interior dynamics of Venus. 相似文献
Aggregation method is seriously impacted by the landscape characteristics, which has been emphasized due to proportional errors. This research proposed an uncertainty weighted majority rule-based aggregation method (UWMRB) to upscale the cropland/non-cropland map. The Cropland Data Layer for 2016 at 30m resolution, with its corresponding confidence level data, were collected to conduct the experiment using UWMRB and majority rule-based aggregation method. Proportional errors of crop/non-crop were used to assess the accuracy of the two methods. Ordinal logistic regression was used to obtain the probability of an error occurring to predict the uncertainty of both methods. The results show that UWMRB can achieve the lower proportional errors with lower uncertainty. Also, it can reduce the influence of complexity and fragmentation of landscape on aggregation performance. Additionally, the examination of UWMRB provides an important view of application of uncertainty information for upscaling land cover maps in an efficient way. 相似文献
Science China Earth Sciences - In the Longmenshan thrust belt, the Dayi seismic gap, an area with few earthquakes, is located between the ruptures of the 2008 Wenchuan Earthquake and the 2013... 相似文献
Precise estimation of soil organic carbon storage is essential to assess carbon sequestration in soils at a regional scale. However, there is great uncertainty regarding such estimations for discontinuous soils, especially in peak-karst regions where soil is distributed between horizontal cracks and vertical fissures. In this study, a modified method was developed to estimate the soil organic carbon density (SOCD) in peak-karst regions in southwest China, and four typical sites were selected to evaluate this methodology. Compared with the conventional method, additional soil distribution characters, such as the average depth and the proportions of the ground surface area represented by continuous soil, soil in cracks and fissures, soil on rocks, and rocky soil, were considered in the estimation. The SOCD under each vegetation type was calculated by totaling the SOCD values for the various types of soil surfaces, and the SOCD for a site was then totaled using the weighted mean method based on vegetation. Using the modified method, the SOCD values were estimated for the four typical sites selected. The estimation results demonstrated that the SOCD values for the karst sites (6.39, 7.52, and 9.22?kg?m?2) were lower than that for the red soil site (10.01?kg?m?2). The SOCD values estimated for the karst sites using the proposed method ranged from 24.3 to 89.6% of the estimates obtained using the conventional method, reflecting previous overestimations. The differences in the estimated SOCD values were mainly due to soil distribution characters. 相似文献