Severe drought is a serious natural disaster that frequently strikes East Asia, highlighting the need to understanding its
drought regime and the associations with Asian monsoon. Tree-ring-based drought reconstructions provide invaluable paleoclimatic
archives for detecting regional and large-scale drought variability and their potential forcings. We herein reviewed many
drought reconstructions from central High Asia and monsoonal Asia and compared their similarities and differences, as well
as their linkages to Asia monsoon. We compared the decadal-scale variability of six drought reconstructions for the central
High Asia, where differing drought variations were found between the western and eastern portions. Seven drought reconstructions
were reviewed for monsoonal Asia, from which a difference in drought variability was observed between the northern and southern
parts. Therefore, we compared the drought variations of the four sub-regions of western and eastern parts of central High
Asia, as well as northern and southern portions of monsoonal Asia. ENSO activity and sea surface temperature of western Pacific
and northern Indian Oceans, coupled with Asian monsoon, play an important role in modulating drought variability of much area
of the East Asia. An improved denser multi-index tree-ring network of longer length for East Asia is necessary for the establishment
of more reliable large-scale drought reconstruction. 相似文献
During the self-weight penetration process of the suction foundation on the dense sand seabed, due to the shallow penetration depth, the excess seepage seawater from the outside to the inside of the foundation may cause the negative pressure penetration process failure. Increasing the self-weight penetration depth has become an important problem for the safe construction of the suction foundation. The new suction anchor foundation has been proposed, and the self-weight penetration characteristics of the traditional suction foundation and the new suction anchor foundation are studied and compared through laboratory experiments and analysis. For the above two foundation types, by considering five foundation diameters and two bottom shapes, 20 models are tested with the same penetration energy. The effects of different foundation diameters on the penetration depth, the soil plug characteristics, and the surrounding sand layer are studied. The results show that the penetration depth of the new suction foundation is smaller than that of the traditional suction foundation. With the same penetration energy, the penetration depth of the suction foundation becomes shallower as the diameter increases. The smaller the diameter of the suction foundation, the more likely it is to be fully plugged, and the smaller the height of the soil plug will be. In the stage of self-weight penetration, the impact cavity appears around the foundation, which may affect the stability of the suction foundation.
