大冰雹指标TBSS在江西的应用研究

利用江西省2002-2007年的地面观测和雷达资料进行统计分析,研究地面降雹与TBSS之间的对应关系,并且对TBSS在大冰雹预警方面的应用进行了探讨。结果表明,TBSS作为≥19 mm的大冰雹的预警指标具有很好的应用效果。其准确警报率(POD)为0.818,错误警报率(FAR)为0.182,而临界成功指数(CSI)达0.692。在多普勒天气雷达产品中,TBSS是一个沿着雷达径向从强风暴核区向外延伸的、具有低的反射率因子值,零或朝向雷达的低速度值和高速度谱宽值的区域。它一般首先出现在中高层(4～9 km),然后逐渐降低,最低可达1.0 km。利用TBSS预报大冰雹的时间提前量最大达到77分钟。实际观测到的TBSS特征存在各种不同的形态,而且不同距离处观测TBSS特征的最佳仰角存在很大差异。总之TBSS特征可以作为大冰雹的有效判据。     

满洲里地震台地磁秒采样数据干扰分析

分析2015年8月—2018年7月满洲里地震台FHDZ-M15地磁总场与分量组合观测系统记录的地磁秒采样观测数据(剔除磁暴与磁扰时间段),发现台站地磁秒采样数据资料所受干扰主要呈阶跃和尖峰形态,通过测量测区地磁场水平梯度,排查周边环境,并对设备和线路进行漏电检测,认为:阶跃形态干扰主要由高压直流输电和车辆停放引起;经逐项排查对UPS加热及输电线路漏电检测,仪器室温度过低和输电线路漏电均造成高频毛刺尖峰形态干扰,对UPS加热处理,干扰状态得到改善,但Z、F分量干扰仍在.受满洲里气候条件等因素限制,未能在2019年完成输电线路更换,当前无法确定干扰是否为输电线路漏电所致,后续将采取相应措施予以确认.     

Molybdenum Mass Fractions and Stable Isotope Compositions of Sedimentary Carbonate and Silicate Reference Materials

A double‐spike method in combination with MC‐ICP‐MS was applied to obtain molybdenum (Mo) mass fractions and stable isotope compositions in a suite of sedimentary silicate (marine, lake, stream, estuarine, organic‐rich sediment, shales, slate, chert) and carbonate reference materials (coral, dolomite, limestones, carbonatites), and a manganese nodule reference material, poorly characterised for stable Mo isotope compositions. The Mo contents vary between 0.076 and 364 μg g^?1, with low‐Mo mass fractions (< 0.29 μg g^?1) found almost exclusively in carbonates. Intermediate Mo contents (0.73–2.70 μg g^?1) are reported for silicate sediments, with the exception of chert JCh‐1 (0.24 μg g^?1), organic‐rich shale SGR‐1b (36.6 μg g^?1) and manganese nodule NOD‐A‐1 (364 μg g^?1). The Mo isotope compositions (reported as δ⁹⁸Mo relative to NIST SRM 3134) range from ?1.77 to 1.03‰, with the intermediate precision varying between ± 0.01 and ± 0.12‰ (2s) for most materials. Low‐temperature carbonates show δ⁹⁸Mo values ranging from 0.21 to 1.03‰ whereas δ⁹⁸Mo values of ?1.77 and ?0.17‰ were obtained for carbonatites CMP‐1 and COQ‐1, respectively. Silicate materials have δ⁹⁸Mo values varying from ?1.56 to 0.73‰. The range of δ⁹⁸Mo values in reference materials may thus reflect the increasingly important relevance of Mo isotope investigations in the fields of palaeoceanography, weathering, sedimentation and provenance, as well as the magmatic realm.     

High‐Precision Cd Isotope Measurements of Soil and Rock Reference Materials by MC‐ICP‐MS with Double Spike Correction

This study presents a high‐precision Cd isotope measurement method for soil and rock reference materials using MC‐ICP‐MS with double spike correction. The effects of molecular interferences (e.g., ¹⁰⁹Ag¹H⁺, ⁹⁴Zr¹⁶O⁺, ⁹⁴Mo¹⁶O⁺ and ⁷⁰Zn⁴⁰Ar⁺) and isobaric interferences (e.g., Pd, In and Sn) to Cd isotope measurements were quantitatively evaluated. When the measured solution has Ag/Cd ≤ 5, Zn/Cd ≤ 0.02, Mo/Cd ≤ 0.4, Zr/Cd ≤ 0.001, Pd/Cd ≤ 5 × 10^?5 and In/Cd ≤ 10^?3, the measured Cd isotope data were not significantly affected. The intermediate measurement precision of pure Cd solutions (BAM I012 Cd, Münster Cd and AAS Cd) was better than ± 0.05‰ (2s) for δ^114/110Cd. The δ^114/110Cd values of soil reference materials (NIST SRM 2709, 2709a, 2710, 2710a, 2711, 2711a and GSS‐1) relative to NIST SRM 3108 were in the range of ?0.251 to 0.632‰, the δ^114/110Cd values of rock reference materials (BCR‐2, BIR‐1, BHVO‐2, W‐2, AGV‐2, GSP‐2 and COQ‐1) varied from ?0.196‰ to 0.098‰, and that of the manganese nodule (NOD‐P‐1) was 0.163 ± 0.040‰ (2s, n = 8). The large variation in Cd isotopes in soils and igneous rocks indicates that they can be more widely used to study magmatic and supergene processes.     

Application of 1013 Ω Amplifiers in Low‐Signal Plasma‐Source Isotope Ratio Measurements by MC‐ICP‐MS: A Case Study with Pt Isotopes

Recent developments in amplifier hardware enable low‐noise measurements of exceedingly small ion beams in isotope ratio analysis, yielding higher precision from smaller samples than ever before. To date, these amplifiers have largely been employed in thermal ionisation instruments, with few applications using plasma‐source (i.e., MC‐ICP‐MS) instruments. Here, we demonstrate the utility of these new generation 10¹³ Ω amplifiers in MC‐ICP‐MS, employing Pt isotopes as a case study, a system that could greatly benefit from the promised advances. The data demonstrate that for samples with low Pt abundance, for a modest increase in uncertainties, the amount of sample required can be reduced by a factor of 50–100. This technique thereby opens up new possibilities for analysis of samples that have low Pt mass fractions or were otherwise impossible to obtain in sufficient quantities.     

贵州冬季一次罕见风雹天气过程分析

本文利用常规气象观测资料、多普勒雷达资料和FNL再分析资料,对2022年1月4日贵州出现的一次风雹天气过程进行分析。结果表明：此次风雹天气由高空槽、低涡切变线、低空急流、地面热低压和地面辐合线的共同作用产生;降雹前有能量锋的建立,降雹期间锋区呈增强趋势;湿层配置表现为500 hPa的空气偏湿,不是明显的上干下湿层结,0 ℃层高度和-20 ℃层高度比春季降雹时的高度偏低70 ~100 hPa;与贵州春、夏两季的雷暴大风对流参数比较,此次过程的CAPE和PWAT小于春、夏两季的阈值,而DCAPE、T75和Td85明显高于春、夏两季阈值;对流风暴的影响过程分为两个阶段,第一阶段的回波带强度更强,组织性更好,形成了弓形回波复合体（BEC）,并伴有后侧入流缺口（RIN）,是雷暴大风出现的主要原因,持续出现的三体散射长钉（TBSS）、高悬的强回波以及宽阔的弱回波区（WER）,使得第一阶段的降雹密度较大,且局地产生大冰雹;第二阶段的回波强度较弱,且组织性较差,因此只产生小冰雹,降雹密度也较小。     

基于整合-激发神经元的自组织映射网络

选取与生物神经元的工作过程较为相似的整合-激发(IF)神经元模型作为传递函数,建立了一个基于整合-激发(IF)神经元的新型自组织特征映射(SOM)网络。通过仿真验证了IF神经元网络的自组织功能,实现对传统自组织网的改进。     

Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation

Recent analysis of a sediment core in the eastern Arabian Sea revealed a negative pulse of about 1% in the δ¹⁸O value of the planktonic Foraminifera around the last glacial maximum (LGM). This pulse has been attributed to (i) increased runoff into the Bay of Bengal from the east-flowing south Indian rivers due to enhancement of the northeast winter monsoon, and (ii) an increase in Arabian sea-surface temperature caused by the weakening of the southwest monsoon at the LGM. We show that the speculation on which the latter hypothesis is based, is not supported by observational data and cannot fully account for the observed magnitude of the spike. With a view to assessing the validity of the first mechanism, we have modelled the mixed layer of the Bay of Bengal as a well-mixed box. The model calculations show that to account for the pulse requires a change of about 10% in either the annual rate of river input or its isotopic composition. For the northeast monsoon to account for the pulse it would mean that the rainfall should have increased by a factor of five to ten during the LGM. No evidence for such an increase is indicated in the available palaeoclimatic data. We explain the freshwater spike by invoking increased discharge of glacial meltwater from the Tibetan plateau into the Bay of Bengal. We show that the proxy climate data from the Indo-Tibetan region that has become available recently provides substantial evidence for the occurrence of a warming event around the LGM, which supports our mechanism.     

MHD oscillations in the solar spike radiation

In this paper the observed 1.4–1.6 s quasi-periodic oscillations in the spike radiation of the microwave outburst of 1981 May 16 are analysed in teras of MHD waves. We point out that the fast magnetoacoustic waves (“sausage” mode) propagating inside and outside a loop can modulate the magnetic field and the pitch angle distribution of the electron beams in the source region. The growth rate of electron-cyclotron-maser instability is then affected to give rise to the quasi-periodic oscillations. Quantitative estimates of relevant physical parameters are given.     

太阳分米波尖峰辐射最小带宽的探讨

云南天文台0.6～1.5GHz太阳射电快速动态频谱仪,在2001年6月24日的射电爆发中观测到大量尖峰。由于观测仪器有相当高的频率分辨率,使我们可以对尖峰的绝对带宽进行更精细的统计分析。由于尖峰数量很大,特别编制了识别尖峰并测量其带宽的软件来进行统计工作。结果发现76%的尖峰的绝对带宽达到仪器频率分辨率1.4MHz,其相对带宽达到0.1%。这比以前关于尖峰辐射带宽的统计结果要小很多。统计结果支持用ECM机制解释尖峰辐射。