Comparative analysis of the cold surge characteristics over China before and after 2000北大核心CSCD

Based on the daily minimum temperature data in China from 1961 to 2018, using n-order polynomial fitting, sliding t-test, empirical Orthogonal Function analysis, Morlet wavelet transform and other methods, this paper reveals the temporal and spatial distribution characteristics of the number of cold surge (CS) day, CS frequency and CS intensity by time and region. The results are as follows. On a national level, the number of CS day, CS frequency, and CS intensity decreased from 1962 to 2000. Specifically, the trend of every element of CS has changed from a previous decrease trend to an increase trend, and the inflection point was around 2000. The CS activity occurred more frequently, became more strengthen, and last for longer time after 2000. There are obvious spatial differences in the number of CS days, CS frequency, CS intensity and their changing trends in China. The number of CS days and CS frequency reach the maximum value in northeast China and northern Inner Mongolia. Meanwhile, the CS intensity value is low in the southeast China and high in the northwest China, with the exception of southern Xinjiang. The changes in the number of CS day and the CS frequency are mainly manifested as the “Northeast, Southwest Reverse Pattern”, the CS intensity is mainly manifested as the “Uniform Change Pattern”. The number of CS day, CS frequency, and CS intensity did not change significantly after, but a significant transition point was detected in 1980. On a regional scale, from 1962 to 2018, the number of CS day, frequency and intensity of cold surge in all regions showed a decreasing trend, while they increased after 2000. In the northern and northeastern of China, mean of three elements of cold surge increased after 2000. The transition year was different in different regions. The transition year of three elements of cold surge in Northeast China were the earliest. Mean value of the number of CS day, CS frequency, and CS intensity have an oscillation period of 3~5 years in total China and all regions. In addition, the periodic oscillations of the number of CS day and CS frequency in all regions are basically the consistent. © 2022 Science Press (China).     

关注土地惠及民生深化农业地质调查成果的建议

种田缺乏科学知识,以及环境污染导致土地污染使耕地质量恶化,已经影响了国家粮食安全和人民身体健康。农业地质调查为改变这种状况,治理土壤污染、保护耕地生态安全、打造绿色农业提供了强有力的决策依据。     

为海龟流泪

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南方海相油气勘探思路与选区评价建议

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大兴安岭地区火山岩风化过程中的微量元素均一化

通过大兴安岭地区数据的宏观分析发现，微量元素低含量岩石形成的土壤中其含量增高，相反高含量岩石形成的土壤中其含量值降低。区域上微量元素在土壤中的分布趋向于均值，这种现象称为微量元素在风化过程中的“均一化”现象。不同微量元素的“均一化能力”不同。微量元素均一化特征的形成是大兴安岭地区成土因素综合作用的结果。     

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提出一种基于线性四叉树结构并顾及矢量与栅格计算性质的Voronoi图生成方法,其核心思想是利用线性四又树结构以减小空间剖分所产生的空间复杂度,改变膨胀模拟操作的计算方向以减小时间复杂度。讨论了基于数学形态学的反向膨胀计算模型及推理出基于该计算模型的几个优化计算性质。实验验证,这种方法能够有效地平衡时空复杂度,并且易于求取邻元,其时间复杂度小于均匀格网结构与常规四叉树结构。一般情况下,空间复杂度小于均匀格网结构。     

远距离声学相关（ACCP）海流剖面仪（S．E．Bradly与S．Y．Kuo）

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