SPATIO-TEMPORAL VARIATION OF SEASONAL EXTREME WET DAYS IN CHINA AND ITS RELATIONSHIP WITH SST ANOMALIES

With daily precipitation records at 586 stations in China for 1960-2004, this study investigates the spatio-temporal variation of the number of extreme wet days (NEWD) for each season in China and its relationship with SST anomalies and associated atmospheric circulation anomaly patterns, in which a threshold of extreme precipitation for a season and a station is defined as the value of the 90th percentile when the precipitation records for wet days during the season are ranked in an increasing order. Results show that there are significant increases of the NEWD along the Yangtze River valley during winter and summer, in North China during winter, in South China during spring, in Northeast China during winter and spring, and in Northwest China throughout the seasons, while there is a remarkable decrease in North China during summer. Besides the linear trend, the NEWD also exhibits considerable interannual and interdecadal variabilities. After eliminating the linear trend, the NEWD anomalies show distinct seasonal patterns. The NEWD anomalies are characterized by a "dipole" mode with opposite phases between northern and southern China in spring and autumn, a "tri-pole" mode with opposite phases between Yangtze River valley and southern and northern China in summer, and a "monopole" mode with the same phase over most of China in winter. The relationship of the NEWD anomalies in China with the SST anomalies in Indian and Pacific Oceans is found to be mainly dependent on the ENSO, and associated atmospheric circulation anomaly patterns for the ENSO's impact on the NEWD in China are identified.

Contribution of the International Reference Ionosphere-2016 Model in the Evidence of the Winter Anomaly

This study is a contribution to the estimation of the winter anomaly in the F2 layer of the ionosphere at low latitudes. The aim is to study the variability of the virtual height (hmF2) of the F2 region of the ionosphere through the predictions of the latest International Reference Ionosphere model (IRI-2016). The present work allows analyzing the temporal evolution of hmF2 according to the different phases of three (3) solar cycles during the quiet geomagnetic activity to estimate the seasonal anomaly at the Ouagadougou station. The analysis of the seasonal profiles shows that the variability of hmF2 is: 1) strongly linked to the solar cycle activity, 2) dependent on the season and 3) variable from one cycle to the next for the same phase. It appears that hmF2 increases during the ascending phase to reach its maximum value at the phase maximum. During the descending phase, it decreases until the phase minimum where it finds its minimum value. The difference between winter and summer on the hmF2 values for each phase of the cycle is obtained at the phase minimum and is estimated to be at least 16 km. In low latitudes, solar irradiation is greater in summer than in winter. From this study, hmF2 values are larger in winter compared to summer indicating an anomaly in the virtual height of the F2 layer of the ionosphere through the predictions of IRI-2016 at the Ouagadougou station.

湖北大冶黄龙山—双港口地区土壤地球化学异常特征及找矿潜力

通过对黄龙山—双港口地区1:1万土壤地球化学测量结果分析,探讨黄龙山—双港口地区元素含量、分布及组合,将区内元素分为Cu-Pb-Zn-Au-Ag-As-Sb中低温组合和W-Sr-Co-Mo高温组合,发现石英闪长岩、栖霞组中Cu、Au、Ag、Pb成矿可能性最大。通过计算各元素异常下限,圈定3处地球化学综合异常,结合地质物探综合分析圈定王家洞和刘家垄2处重点找矿靶区,其中刘家垄找矿靶区钻探工程验证发现铜矿体。

磁异常小波多尺度分解及危机矿山的深部找矿:以大冶铁矿为例

大冶铁矿是多年开采老矿山，浅部的铁矿已开采殆尽，为了进一步挖潜，利用小波多尺度分析方法，将磁异常分解到不同尺度空间，结合谱分析方法解释深部盲矿体．理论模型和19-1勘探线的实际资料的小波分解结果表明，该方法比常规的空间延拓、高次导数、匹配滤波等方法要好．通过处理与解释指出了西段（尖林山、龙洞、铁门坎）五阶小波细节已无剩余异常存在，推测在1000m以下已没有大型的铁矿体存在．但在东段（尖山、犁头山）五阶小波细节还有剩余异常，推测1000m深部可能还有铁矿体．根据小波多尺度分析方法结合人机交互反演推断15-12线有铁矿体，2005年9月布钻验证，在15～1线打到30多米厚磁铁矿体．

大冶—九瑞地区局部地质异常特征与成矿

从地质异常的角度，重点分析了大冶—九瑞地区主要地质异常的特征及其对成矿的影响．由分析可知：基底断裂异常控制了本区若干重要规模较大的隐伏岩基及伴生矿田，而盖层构造异常控制铜金矿床和铁铜矿床的空间位置；地层的地球化学异常和岩相古地理异常是造成一些铜金矿床层控性的主要地质因素；盖层的岩性异常为含矿热液的渗流、循环、聚集和矿质沉淀等一系列成矿作用提供了有利的物理和化学条件；中生代岩浆岩的异常活动期也是本区主要的铁铜成矿期，岩浆岩系统的多层分枝和分带性结构控制了本区成矿系统的三维空间分布．在上述分析的基础上，构置了地质组合熵作为反映控矿地质因素组合系统结构复杂程度的综合变量，并圈定出组合熵异常，由此确定了综合地质异常与矿床的关系．

综合物探方法在湖北大冶鸡冠咀铜金矿深部及外围找矿中的应用

以湖北大冶鸡冠咀铜金矿床深部及其外围找矿预测为目标,在深入认识鸡冠咀铜金矿床地质特征的基础上,对研究区重力、磁测、电法测量资料进行精细反演,研究含矿地质体与物探异常的对应关系,获取矿区深部和外围物探异常信息。研究证实研究区岩矿石物性差异明显、与矿有关的地质体与重磁异常具有良好的吻合性,研究区内断裂接触带、大理岩俘虏体、隐伏岩体表现出重磁同高、重磁异常梯度带等特征,是寻找深部盲矿体的有利部位。总结了5种地球物理找矿标志,构建了“一个主要目标,两种分析,三种方法,五个找矿标志”的矽卡岩型铜金矿床的地球物理找矿模式,对鸡冠咀矿区深部及外围进行靶区优选,指导鄂东南矿集区矿产勘查工作,具有良好的示范作用。

Seasonal and Sub-Seasonal Circulation Anomalies Associated with Persistent Rainy Days in 2018/2019 Winter in Shanghai, China

Shanghai experienced the longest rainy days in 2018/2019 winter since 1988. The physical cause of such an unusual climate condition was investigated through the diagnosis of observational data. From a seasonal perspective, a long persistent rainy winter was often associated with an El Ni?o condition in the equatorial Pacific. This abnormal oceanic condition induces a remote teleconnection pattern with pronounced low-level southerly anomalies over East China.The wind anomalies transported moisture from tropical oceans and caused persistent rainfall in East Asia. Meanwhile, the local rainfall time series exhibited a strong quasi-biweekly oscillation (QBWO). Three persistent rainy events were identified in the 2018/2019 winter and they all occurred during the active phase of the QBWO. The first two events were associated with a low pressure anomaly west of Shanghai. Southerly anomalies associated with the low pressure system advected high mean moisture into central eastern China, leading to the persistent rainfall there.The third event was associated with a high pressure anomaly in lower troposphere to the east of Shanghai, which induced anomalous southerlies to its west, favoring the occurrence of rainfall in Shanghai. The result suggests the importance of high-frequency variability in affecting seasonal rainfall anomalies.

Impacts of the SSTs over Equatorial Central–Eastern Pacific and Southeastern Indian Ocean on the Cold and Rainy/Snowy/Icy Weather in Southern China

Low temperature together with snow/freezing rain is disastrous in winter over southern China.Previous studies suggest that this is related to the sea surface temperature(SST)anomalies,especially La Nina conditions,over the equatorial central–eastern Pacific Ocean(EP).In reality,however,La Nina episodes are not always accompanied by rainy/snowy/icy(CRSI)days in southern China,such as the case in winter 2020/2021.Is there any other factor that works jointly with the EP SST to affect the winter CRSI weather in southern China?To address this question,CRSI days are defined and calculated based on station observation data,and the related SST anomalies and atmospheric circulations are examined based on the Hadley Centre SST data and the NCEP/NCAR reanalysis data for winters of1978/1979–2017/2018.The results indicate that the CRSI weather with more CRSI days is featured with both decreased temperature and increased winter precipitation over southern China.The SSTs over both the EP and the southeastern Indian Ocean(SIO)are closely related to the CRSI days in southern China with correlation coefficients of-0.29 and 0.39,significant at the 90%and 95%confidence levels,respectively.The SST over EP affects significantly air temperature,as revealed by previous studies,with cooler EP closely related to the deepened East Asian trough,which benefits stronger East Asian winter monsoon(EAWM)and lower air temperature in southern China.Nevertheless,this paper discovers that the SST over SIO affects precipitation of southern China,with a correlation coefficient of 0.42,significant at the 99%confidence level,with warmer SIO correlated with deepened southern branch trough(SBT)and strengthened western North Pacific anomalous anticyclone(WNPAC),favoring more water vapor convergence and enhanced precipitation in southern China.Given presence of La Ni?a in both winters,compared to the winter of 2020/2021,the winter of 2021/2022 witnessed more CRSI days,perhaps due to the warmer SIO.