用T106L19产品制作春季西南大风预报   总被引：5，自引：0，他引：5  

张立祥  陈力强  韩秀君  张宁娜 《气象》1998,24(7):45-49

使用最近１０年的逐日资料,分析了辽宁省西南大风的天气气候特征。应用天气动力方法,分析了产生西南大风的天气特点,发现了一些预报西南大风的重要物理因子,建立了基于Ｔ１０６Ｌ１９输出产品的预报方法并在业务中应用。结果表明,该方法预报效果明显好于主观预报  相似文献   

疫情冲击下全球跨境电商物流韧性的时空异质性研究     

余金艳  张英男  刘卫东  肖作鹏 《地理研究》2021,40(12):3333-3348

新冠疫情给全球化进程带来巨大冲击,流动性被切断是其中重要原因,尤以物流延滞造成的物资短缺影响最为严重。作为供应链的重要组成部分,国际物流时效性和格局在疫情冲击下发生了重要变化。通过对全球疫情及跨境电商物流大数据的挖掘、计算和分析,从韧性角度对物流时效的时空异质性展开研究,分析物流受冲击变化的特征,以及韧性空间格局、阶段差异和时间过程,并结合定量分析其影响因素。研究发现：在疫情冲击下,物流时效性呈现“衰减波”特征,表现出明显的抵抗力阶段、恢复力阶段,以及韧性提升;北美、西欧的物流韧性相对较低,东亚及其邻近的中亚、中东欧、西亚、北非区域则相对较高,尤其是抵抗力阶段差异明显;全球物流恢复力指数普遍高于抵抗力指数,北美、西欧、大洋洲部分样本恢复力较弱;时间过程上可分为3个时期,并呈现出一定的空间传导现象：前6个月急速下降、艰难抵抗后平稳恢复,第7至第11个月整体向好、局部震荡,第12至第13个月全球小幅波动后较快恢复;影响物流韧性时空异质性的因素较为综合,其中物流网络关系、疫情严重程度的影响相对显著。  相似文献   

The airborne contagiousness of respiratory viruses: A comparative analysis and implications for mitigation     

《地学前缘(英文版)》2022,13(6):101285

The infectious emission rate is a fundamental input parameter for airborne transmission risk assessment, but data are limited due to reliance on estimates from chance superspreading events. This study assesses the strength of a predictive estimation approach developed by the authors for SARS-CoV-2 and uses novel estimates to compare the contagiousness of respiratory pathogens. We applied the approach to SARS-CoV-1, SARS-CoV-2, MERS, measles virus, adenovirus, rhinovirus, coxsackievirus, seasonal influenza virus and Mycobacterium tuberculosis (TB) and compared quanta emission rate (ER_q) estimates to literature values. We calculated infection risk in a prototypical classroom and barracks to assess the relative ability of ventilation to mitigate airborne transmission. Our median standing and speaking ER_q estimate for SARS-CoV-2 (2.7 quanta h^?1) is similar to active, untreated TB (3.1 quanta h^?1), higher than seasonal influenza (0.17 quanta h^?1), and lower than measles virus (15 quanta h^?1). We calculated event reproduction numbers above 1 for SARS-CoV-2, measles virus, and untreated TB in both the classroom and barracks for an activity level of standing and speaking at low, medium and high ventilation rates of 2.3, 6.6 and 14 L per second per person (L s^–1 p^–1), respectively. Our predictive ER_q estimates are consistent with the range of values reported over decades of research. In congregate settings, current ventilation standards are unlikely to control the spread of viruses with upper quartile ER_q values above 10 quanta h^?1, such as SARS-CoV-2, indicating the need for additional control measures.  相似文献   

Impact of COVID-19 lockdown on the optical properties and radiative effects of urban brown carbon aerosol     

《地学前缘(英文版)》2022,13(6):101320

Intensive measurements were conducted in Xi’an, China before and during a COVID-19 lockdown period to investigate how changes in anthropogenic emissions affected the optical properties and radiative effects of brown carbon (BrC) aerosol. The contribution of BrC to total aerosol light absorption during the lockdown (13%–49%) was higher compared with the normal period (4%–29%). Mass absorption cross-sections (MACs) of specific organic aerosol (OA) factors were calculated from a ridge regression model. Of the primary OA (POA), coal combustion OA (CCOA) had the largest MACs at all tested wavelengths during both periods due to high molecular-weight BrC chromophores; that was followed by biomass burning OA (BBOA) and hydrocarbon-like OA (HOA). For secondary OA (SOA), the MACs of the less-oxidized oxygenated OA (OOA) species (LO-OOA) at λ = 370–590 nm were higher than those of more-oxidized OOA (MO-OOA) during both periods, presumably due to chromophore bleaching. The largest contributor to BrC absorption at the short wavelengths was CCOA during both periods, but BrC absorption by LO-OOA and MO-OOA became dominant at longer wavelengths during the lockdown. The estimated radiation forcing efficiency of BrC over 370–600 nm increased from 37.5 W·g^?1 during the normal period to 50.2 W·g^?1 during the lockdown, and that enhancement was mainly caused by higher MACs for both LO-OOA and MO-OOA. This study provides insights into the optical properties and radiative effects of source-specific BrC aerosol when pollution emissions are reduced.  相似文献   

从生产能力到转产能力——基于对疫情期间中国转产情况的思考     

朱晟君  殷子涵  杨博飞  贺灿飞 《地理研究》2021,40(2):293-309

长期以来,中国生产力布局都较为关注产业生产能力而忽视产业转产能力.2020年新型冠状病毒肺炎疫情全球爆发期间,中国许多城市通过产业转产有效缓解了防疫物资供给紧张问题,使得城市产业转产能力引起广泛关注.本文利用从国家药品监督管理局官网整理得到的国产医用器械注册证数据与中国海关进出口数据库、中国工业企业数据库等数据论述了演...  相似文献   

Lockdown as an Empirical Strategy to Curb Air Pollution: Evidence from a Quasi-Natural Experiment     

Manish Yadav  Nitin Kumar Singh  Bhupendra Kumar Soni  Kusum Soni  Pawan Kumar Singh 《洁净——土壤、空气、水》2023,51(1):2200059

In this study, three approaches namely parallel, sequential, and multiple linear regression are applied to analyze the local air quality improvements during the COVID-19 lockdowns. In the present work, the authors have analyzed the monitoring data of the following primary air pollutants: particulate matter (PM₁₀ and PM_2.5), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO). During the lockdown period, the first phase has most noticeable impact on airquality evidenced by the parallel approach, and it has reflected a significant reduction in concentration levels of PM₁₀ (27%), PM_2.5 (19%), NO₂ (74%), SO₂ (36%), and CO (47%), respectively. In the sequential approach, a reduction in pollution levels is also observed for different pollutants, however, these results are biased due to rainfall in that period. In the multiple linear regression approach, the concentrations of primary air pollutants are selected, and set as target variables to predict their expected values during the city's lockdown period.The obtained results suggest that if a 21-days lockdown is implemented, then a reduction of 42 µg m⁻³ in PM₁₀, 23 µg m⁻³ in PM_2.5, 14 µg m⁻³ in NO₂, 2 µg m⁻³ in SO₂, and 0.7 mg m⁻³ in CO can be achieved.  相似文献   

基于集合经验模态分解和自回归-移动平均模型的COVID-19流行病全球预测系统预测结果改进          下载免费PDF全文

Chuwei Liu  Jianping Huang  Fei Ji  Li Zhang  Xiaoyue Liu  Yun Wei  Xinbo Lian 《大气和海洋科学快报》2021,14(4):52-57

2020年,新型冠状病毒肺炎(COVID-19)在世界范围内迅速传播.为准确预测各国每日新增发病人数,兰州大学开发了 COVID-19流行病全球预测系统(GPCP).在本文的研究中,我们使用集合经验模态分解(EEMD)模型和自回归-移动平均(ARMA)模型对GPCP的预测结果进行改进,并对发病人数较少或处于发病初期,不...  相似文献   

温州市新型冠状病毒肺炎时空分布格局演化分析     

余正  黄加坡  陈袁芳  陈炳蓉  徐刚  王晶  龙程 《测绘通报》2020,(7):45

本文首先结合社交媒体信息和温州市新型冠状病毒肺炎（COVID-19）发展态势,获取疫情传播先验知识,进一步采用DBSCAN自适应聚类算法,分析温州市COVID-19时空分布格局与演化规律。结果表明：①温州市COVID-19易在20~59岁的青壮年人群,以及商业服务人员、农民和工人人群间传播;②我国针对人口流动采取的系列措施能够有效遏制疫情进一步蔓延,使得温州市聚类空间簇数量在时间上呈现先增加后减小的趋势;③温州市鹿城区银泰商贸附近、乐清市南部和瑞安市西部具有疫情扩散高风险,后期需增强防控力度。本文细粒度地分析了温州市疫情时空演化过程,能够更好地辅助温州市政府部门更精细地部署疫情防控措施。  相似文献   

新冠疫情对中国经济的影响及政策讨论     

张凯煌  千庆兰 《热带地理》2020,40(3):396-407

新冠疫情对全球经济造成了严重冲击,在政策空间有限的背景下,讨论结构化政策工具和区域应对方案显得尤为重要。股票市场是国民经济的风向标,因此文章利用在A股市场上市的企业作为研究对象,从产业、主体规模以及区域等维度分析疫情对中国上市企业第一季度财务数据的影响。结果表明：1）除农、林、牧、渔业正增长外,大部分产业均遭受营运利润下滑、经营现金流减少、资产负债率提高等多重打击。各产业中,服务业面临更大挑战。个体的行为决策、政府的停工停产措施以及产业特性是造成这一变化的主要原因。2）新冠疫情对中小市值主体的影响大于大企业。疫情期间,大市值企业的营运利润能力、现金流水平得到优化,资产负债结构表现稳定。这主要是由运营能力差异和马太效应所造成的。3）制造业、服务业和建筑与房地产业上,发达地区相较于欠发达地区承受了更大冲击,这主要受地方人口结构和土地价格影响。金融业上,北京、上海、广东均出现了扰动,而江苏则表现出增长趋势,区域金融业结构特征和企业经营能力是造成这一现象的主要原因。医药产业受到一定程度的冲击,但产业基础好的地区仍出现增长态势,这主要是由医药需求出现取消或推迟、部分药物和设备需求存在紧迫性、优势区域需要承担相应的社会责任造成的。在此基础上,文章讨论了采取更加积极的财政政策、深入优化企业融资环境和差异化选择区域政策工具等政策建议。  相似文献   

新冠肺炎疫情前后游客出行行为的时空特征研究——以中国香港为例     

徐阳  彭澎  陆锋  高嘉良  程诗奋 《地理研究》2022,41(12):3199-3213

新型冠状病毒肺炎疫情对香港旅游业产生了巨大的冲击,掌握疫情期间游客出行的时空变化特征,对后疫情时代旅游业复苏和发展至关重要。本文基于2019年和2020年社交媒体的旅游评论数据,采用时序统计、复杂网络分析等方法,对比分析疫情前后香港旅游网络的演化特征,并结合旅游目的地语义刻画游客出行规律。结果表明：(1)游客出行规律呈现出一定程度变化,与疫情前相比,游客在一次出游行程中所访问的旅游目的地数量大幅下降;(2)热门目的地仍然在香港旅游网络中承担着连接其他目的地的重要作用,而围绕热门目的地形成的旅游网络社区由疫情前的空间显著集聚转为相对稀疏分布,但网络社区内部目的地的空间分布较疫情前变得更加集聚;(3)在游客选择出行目的地方面,热门目的地访问量急剧减少,而以往游客较少且地理位置较为偏僻的目的地,在游客出行目的地选择时变得更被关注,但产业目的地始终是香港旅游中最热门的旅游目的地类型。  相似文献