武定6.5级地震前后环境剪应力场动态变化

采用陈培善等从断裂力学观点研究地震破裂过程,提出的由地震波和地震基本参数等资料估算地震震源处剪切应力强度值的方法,对发生在武定震区及其附近的中小地震测算了剪切应力值,据此对武定６．５级地震前后环境剪应力场动态变化作了追踪分析。结果表明,武定地震发生在环境剪应力场具有高值分布背景的地区。强震孕育经历了环境应力场由低－高－低－高的多次起伏变化,反复增强的过程。震后环境剪应力场逐渐减弱,最终回复到正常状     

腾冲火山区某些地震学参数特征

测定了腾冲火山区地震震中位置和震源深度,对火山区及附近的震源深度、地震时距曲线和地震波速度等地震学参数特征作了分析。结果表明,腾冲火山区地震震源深度相对较小,向周围地区逐渐增大,震源深度分布的低值区,又是环境剪应力场的值分布区。腾冲火山区Ｐ、Ｓ波平均速度,明显比外围地区小,腾冲火山区存在低速区。这些地震学参数分布的差异,一方面反映出地区作为火山区的固有特征及其地域分布的大小,同时也揭示出腾冲火山在     

贺兰山东麓两次局地暴雨过程的湿位涡诊断分析

利用自动气象站雨量资料、MICAPS4调阅资料以及NCEP再分析资料,对比分析了2016年8月21日和2018年7月22日宁夏贺兰山东麓两次局地暴雨过程的降水特征、环流形势等,重点对两次过程的湿位涡场进行了诊断分析。结果表明:两次暴雨过程第一阶段均为暖区降水,表现出降水范围小、时间短、强度大,相对第一阶段降水,第二阶段降水范围较大、雨强较小。两次过程强降水均发生在假相当位温(θse)等值线密集区,并沿低空急流轴呈长条状分布,强降水时段与θse最大值出现时间相一致。暴雨区位于位涡(PV)负值中心区附近,暴雨发生发展过程与PV负值中心的移动和变化较为一致,PV负值中心的加强和减弱以及移动方向对局地暴雨的预报有很好的指示意义。对流层500 hPa以上湿位涡正压项(MPV1)正的大值区对应700 hPa以下负的大值区,正负中心区垂直叠加的配置有利于暴雨发生发展。垂直剖面图上600 hPa都存在湿位涡斜压项(MPV2)负极值中心,对流层中低层MPV2负极值中心的强度和维持时间以及变化对局地暴雨的预报有一定的指示作用。     

Effects of Doubled Carbon Dioxide on Rainfall Responses to Radiative Processes of Water Clouds

The effects of doubled carbon dioxide on rainfall responses to radiative processes of water clouds are investigated in this study. The two groups of two-dimensional cloud-resolving model sensitivity experiments in pre-summer heavy rainfall around the summer solstice and tropical rainfall around the winter solstice are conducted and their averages over 5 days and model domain are analyzed. In the presence of radiative effects of ice clouds, doubled carbon dioxide changes pre-summer rainfall from the decrease associated with the enhanced atmospheric cooling to the increase associated with the enhanced infrared cooling as a result of the exclusion of radiative effects of water clouds. Doubled carbon dioxide leads to the reduction in tropical rainfall caused by the removal of radiative effects of water clouds through the suppressed infrared cooling. In the absence of radiative effects of ice clouds, doubled carbon dioxide changes pre-summer rainfall from the increase associated with the increased atmospheric warming to the decrease associated with the weakened release of latent heat caused by the elimination of radiative effects of water clouds. The exclusion of radiative effects of water clouds increases tropical rainfall through the strengthened infrared cooling, which is insensitive to the change in carbon dioxide.     

Quantification of permafrost creep provides kinematic evidence for classifying a puzzling periglacial landform

Mechanical processes operating on the slope surface or at depth control the dynamics of alpine landforms and hold critical information of their geomorphological characteristics, yet they often lack systematic quantification and in-depth interpretation. This study aims to address a long-standing issue concerning geomorphological classification from a kinematic perspective. A group of periglacial landforms consisting of several lobes were discovered in the East Kunlun Mountains of China 30 years ago but were ambiguously classified as rock glaciers and later as gelifluction deposits. Here, we use satellite Interferometric Synthetic Aperture Radar to quantitatively characterize the spatial and temporal changes of the surface movement of these landforms. We observe that: (1) its 17 lobes show a pattern of landform-scale and uniform surface movement, especially during May to October; (2) the lobes move at a spatial mean downslope velocity of 10 to 60 cm/yr and a maximum velocity as high as 100 cm/yr in summer; (3) the landforms are nearly inactive from winter to late spring. Based on these observations, we postulate that the movement of the lobes are driven by deep-seated permafrost creep which typically occurs in rock glaciers. The debris of Lobe No.4 is composed of both boulders and pebbles supported by fine-grained matrix generated from the in situ weathering process. It develops a talus-like oversteepened front around 40° and a convex transverse profile perpendicular to the creep direction, which are also characteristic features of a rock glacier. Piecing these observations together, we identify Lobe No.4 as a debris-mantled-slope-connected rock glacier, with the gelifluction process occurring on the surface as small-scale and discrete events. © 2020 John Wiley & Sons, Ltd.     

云南强震活动的多层次动力源分析

对云南地区多层次动力过程作了分析研究，结果表明，若以两大板块之间在边界上的相互作用为最高层次的动力作用，云南地区现代构造运动至少包括三个层次的动力作用过程：(1)印度板块和亚欧板块两大地壳板块在喜马拉雅碰撞带东部弧顶和东翼相互作用产生的边界动力源对云南地区产生的直接影响和间接作用；还有菲律宾海板块对亚欧板块的北西西向的推挤，通过华南地区对云南东部的间接作用，构成了云南地区现代构造运动第一层次动力作用；(2)以康滇菱形断块为主体，包括川青断块、滇西南断块带等板内断块的整体向南南东—南东方向的相对移动产生的动力作用，是第二层次的动力作用；(3)由于板内断块边界断裂运动速率的差异，主要是水平滑动速率差异造成的板内断块内部次级断块移动产生的动力作用，是第三层次的动力作用。对印度板块和亚欧板块两大地壳板块碰撞挤压带东部弧顶和东翼相互作用产生的边界动力源与云南及邻区构造运动、构造应力场分布格局和强震活动关系作了分析研究，认为云南及邻区多层次动力作用过程，是强震活动时空分布的主要原因。     

丽江7.0级地震预报判据及地震学主要异常

介绍了丽江７．０级地震裂度、地震地质及中、短、临预报简况。中、短期预报准确，短临预报向云南省政府打了招呼。重点讨论中短期预报中使用的主要地震学判据。指出丽江７．０级地震前，中甸一下关地震带６级地震时间间隔已达１９ａ，超过历史极限。该带北段１９８３－１９９３年１０ａ内无Ｍ≥５地震；震中周围形成一长约１５０ｋｍ空段，１９９０－１９９５年６ａ内震源区Ｍ≥３．５地震出现平静异常。总之，震源周围地区小震及中     

一次梅雨锋暴雨过程中多尺度能量相互作用的研究II.实际应用

本文利用中国自动站与CMORPH（Climate Prediction Center Morphing technique for the production of global precipitation estimates）融合的逐时降水量0.1°网格数据集资料挑选出一次典型的梅雨锋暴雨个例,运用WRF中小尺度模式进行模拟,对模拟得到的高分辨率结果进行Barnes滤波,最后将滤波结果代入动能和位能方程中,目的是定量地分析各个尺度能量的变化以及它们之间的相互作用对暴雨强度的影响。研究发现:模式模拟的降水过程和强度与实况较为吻合,推导的能量方程适用于这次暴雨过程。三种尺度能量之间的相互作用包含了各种跨尺度能量的相互作用。在整个暴雨过程中,跨尺度之间的斜压能量转换包括位能向动能的能量转换和动能向位能的能量转换。同尺度之间的斜压能量转换总是单向的,且量值较大,动能的强度主要靠位能向动能的能量转换来维持。斜压能量转换的多少影响着暴雨的强弱。大尺度斜压能量转换在中高层比较强,中尺度斜压能量转换在低层较强,尤以β中小尺度系统变化最为显著,β中小尺度系统扰动是影响暴雨强度的关键系统。风切变的大小影响各尺度动能之间的能量转换。温度或位温梯度的大小影响各尺度位能之间的能量转换。位能与动能之间的能量转换主要与各尺度垂直速度和温度的垂直分布有关,暖空气上升冷空气下沉是各个尺度位能向动能转换的主要过程。     

腾冲火山区及周围地区震源机制与构造应力场分布特征

对腾冲火山区及周围地区强震震源深度和震源机制空间分布及区域现代构造应力场特征进行了研究。由我国西南地区直到缅甸中深源地震带的区域构造应力场空间分布格局,充分显示出我国西南地区在现代构造运动过程中,受到以印度板块对亚欧板块碰撞挤压作用为主要动力源,在东部同时受到太平洋板块和菲律宾海板块远距离作用影响的总体特征。腾冲火山区主要受到印度板块在缅甸中深源地震带产生的侧面挤压剪切的直接作用。腾冲火山区所属的腾冲龙陵地震带是西南地区区域构造应力场分区的一条重要边界。腾冲火山区主要受到北东———北东东向的区域压应力场作用,同时也可能受到东侧毗邻应力场分区南南东———南东向压应力场的影响。     

Near-surface air temperature lapse rates in Xinjiang,northwestern China

Theoretical and Applied Climatology - Lapse rates of near-surface (2 m) air temperature are important parameters in hydrologic and climate simulations, especially for the mountainous areas...