基于热带和热带外独立影响途径的中国东部冬季阴天频次的季节预测

The temporal-spatial characteristics of the leading mode of winter cloudy day frequency (CDF) across eastern China are revealed via Empirical Orthogonal Function (EOF) analysis of daily cloud cover obtained from 1078 gauge stations in eastern China from 1961 to 2003. We identified the two influence routes of this leading mode, which we used to conduct a physical-motivated empirical model to the seasonal forecast of the winter CDF in eastern China. The results demonstrate that: (1) The first EOF mode of winter CDF explains 59% of the total variance, which is significant and independent of the other modes. This mode primarily demonstrates a homogenous spatial pattern across eastern China with dominating interannual variability. In the positive phase of this mode, a significant lower-level anticyclonic circulation anomaly occurs across the North Pacific. The anomalous southerly wind across the western flank of the anticyclonic could transport water vapor from the tropical ocean to eastern China, resulting in higher CDF. (2) the preceding persistent North Pacific dipole (NPD) pattern during August and September, and lowering of sea level pressure across midlatitude North Atlantic (LPA) from September–November are the two independent drivers for the formation and variation of this mode. The cold SSTA in the western pole of the NPD is advected southward to the tropical western Pacific using the anomalous northerly of the local low-level anomalous cyclone, forming the Bjerknes feedback, which maintains and accelerates the “cold west warm east” zonal SSTA dipole pattern in the tropical Pacific. This tropical Pacific zonal SSTA pattern stimulates zonal convection dipole, which induces a meridional atmospheric teleconnection in the North Pacific. The anomalous North Pacific anticyclones’ southerly is conducive to more CDF in eastern China. The LPA demonstrates the transition of a quasi-stationary Rossby wave train in mid-high latitudes Eurasia from autumn to winter. In winter, the southerly on the west of the barotropic anticyclonic anomaly across Northeast Asia, the terminal of the Rossby wave train, could result in increased CDF in eastern China. (3) Based on these two independent routes of physical mechanisms from both tropics and ex-tropics, a physics-motivated empirical model is conducted, which demonstrates potential independent prediction skill during the ten years of 2004–2013. The results are essential references for operational departments on seasonal prediction. © 2023 Science Press. All rights reserved.     

玛纳斯地区大棚蔬菜受气象因素的影响及预防措施

通过对玛纳斯地区大棚温室蔬菜生长情况的观测,并与本地区的气象因素进行比较,得出气象因素对大棚温室蔬菜的影响。     

知识介绍

珊瑚 珊瑚属于腔肠动物,是由许多腔肠动物个体组成的群体。这类动物包括低等的水螅、水母和海葵等。大多数腔肠动物都具有软的体躯,但是某些珊瑚类则被坚硬的钙质外套包围着。腔肠动物的共同特点之一是都有螫刺     

危险的海洋生物——鲨鱼

现有的鲨鱼约300余种,至今认为有害的不过20几种。虽然某些鲨鱼的地理分布广泛,但是鲨鱼侵袭人的事件多发生在纬度40°N—40°S之间的暖水中。 较危险的鲨鱼公认的是真鲨属的大白鲨、虎鲨、灰鲨。但是任何超过4英尺长的鲨,有发达的牙齿者都是危险的。假如水中有血或其     

湍流对天津颗粒物粒径谱分布的影响北大核心CSCD

大气颗粒物粒径谱分布不仅受到温度、湿度和风等气象因素影响,也与湍流等边界层特征密切相关。基于2018年11月同步观测的14.6~660.0 nm颗粒物粒径谱和相关气象数据,探讨不同气象因子,特别是湍流对颗粒物粒径谱分布的影响。研究结果表明:气温升高有利于促进核模态颗粒物总数浓度的增加,相对湿度升高可减少核模态和爱根模态颗粒物的总数浓度,同时增加积聚模态的颗粒物总数浓度。风速、湍流动能、摩擦速度、湍流强度等增加,对爱根模态和积聚模态的颗粒物起稀释、清除作用,但可促进核模态颗粒物总数浓度的增长。与湍流日变化相反,爱根模态和积聚模态的颗粒物总总数浓度的日变化呈现昼低夜高的变化趋势,清洁日核模态颗粒物总数浓度在午后持续增加,并在傍晚前达到峰值。核模态颗粒物总数浓度的增加相对于湍流的发展存在时间上的滞后性,当湍流发展3~5 h后,核模态颗粒物总数浓度开始明显增加。     

合肥市物流空间区位特征与形成机理

以合肥市111个专业大市场、852家物流企业、38个物流节点为样本,结合合肥市2014年交通网络、工业园要素地图,采用GIS技术,探讨合肥市物流空间特征及形成机理。研究结果显示:(1)陆路交通网络对物流空间区位选择影响显著,而内河港口、机场对其影响不显著;(2)城区物流空间呈单中心等级扩散格局,中心城区与近郊区为物流企业、专业大市场布局热点,远郊区主要布局规模(大中型)物流节点,且无明显物流节点体系分层现象;(3)物流空间与工业布局不协同,区域差异明显,瑶海区、庐阳区物流空间集聚,而包河区与蜀山区无明显集聚现象。     

变形监测在重庆市五童路小石坝高架桥应急抢险工程中的应用

本文以重庆市五童路小石坝高架桥应急抢险工程为实例，简述变形监测常规大地测量方法在大桥变形监测中的应用以及其在桥梁安全隐患分析评估中的作用。     

安徽淮北地区寒武系“崮山阶”—凤山阶新知

根据三叶虫Acanthometopus obesus、Trianguraspis nodus、Petalocephalus laevis、Taishaniasp.等的发现,将淮北地区捻山剖面原属凤山阶的地层划归长山阶,以Acanthometopus带作为该区长山阶最顶部的三叶虫带,淮北地区凤山阶与长山阶的界线应在Ptychaspis-Tsinania带与Acanthometopus带之间;通过与标准剖面及邻近地区的对比,淮北地区的崮山组应予解体,原崮山组上部与炒米店组岩性一致,应划入炒米店组,其下部岩性与张夏组一致,应划入张夏组,淮北地区无崮山组。淮北地区的炒米店组跨越了整个长山阶和凤山阶中下部,据岩性差异可分为上、下两段;炒米店组在华北地区具有明显的穿时性,其底界从长山阶底界跨至凤山阶顶界。     

冰冻圈变化的可预测性、不可逆性和深度不确定性

IPCC第六次评估报告(AR6)第一工作组报告对气候系统各要素的可预测性(predictability)、不可逆性(irreversibility)和深度不确定性(deep uncertainty)给出了新认识.文中基于此对全球冰冻圈变化的上述三方面加以总结和归纳.总体来看,无论何种排放情景,半球和全球尺度上冰冻圈各要...     

消除背景影响的化探异常圈定方法——以张家口地区为例

由于不同成矿元素在不同岩性地层单元中的背景值存在较大差异,如采用符合正态分布的统计法计算元素异常下限值,会使得矿床可能并不分布在圈定的地球化学异常范围内,异常区可能仅是高背景岩石的反映。本文以张家口1∶20万化探扫面数据为例,圈定了Cu、Zn、V、Ti、Ni等受岩性影响较大元素的异常,结果表明传统统计方法所圈元素异常区受岩性控制作用明显。而考虑岩性本底含量的衬度值法所圈异常,不仅能有效避免岩性对异常的控制作用,且能在低背景岩石单元中圈出新异常,具有较好的找矿指示意义。