Dynamic temperature fluctuations are a key driver of morbidity and mortality. To characterize the health impacts of drastic temperature fluctuations, a novel metric was developed to calculate real-time temperature deviation (TD) from previous exposures (hypothetical adaptation baseline). We used quasi-Poisson models to investigate the association between TD and cause-specific mortality in four Chinese megacities with distinct climatic conditions. Cause-specific mortality data were collected from Harbin, Beijing, Chengdu, and Shanghai between 2010 and 2016, comprising 249,110 respiratory and 740,925 cardiovascular death cases. Seasonal temperature trends were incorporated as effect modifiers. Rapid warming increased mortality risks across all cities, yet pronounced north–south divergence existed in population vulnerability. Negative TD yielded significant protective effects during warming seasons. The subtropical Shanghai exhibited the highest risks associated with P90-level TD, with RRs reaching 1.063 (95% CI: 1.038–1.089) for respiratory mortality and 1.076 (95% CI: 1.060–1.092) for cardiovascular mortality. Northern residents were susceptible to rapid warming as well as extreme temperature declines in cooling periods, with higher mortality risks from respiratory diseases than cardiovascular diseases. In comparison, southern residents suffered excess mortality risks from both abrupt warming and frequent moderate cooling events. At P10 of TD0-7, the highest RRs of cardiovascular and respiratory mortality were found in Chengdu (RR=1.015, 95%CI: 1.005–1.025) and Shanghai (RR=1.019, 95%CI: 1.005–1.033), respectively. Our findings reveal substantial geographical and seasonal heterogeneity in the health impacts of dynamic temperature fluctuations, highlighting the need for flexible, location- and season-specific health risk mitigation and climate adaptation strategies.

Climate change has amplified the variability and intensity of cold weather, contributing to a growing health burden. Cold exposure serves as a significant, yet preventable, environmental trigger for acute chest pain–related life-threatening cardiovascular diseases (CVDs), such as acute coronary syndrome, acute aortic dissection, and pulmonary embolism. This scientific statement synthesizes multidisciplinary evidence from meteorology, environmental epidemiology, basic science, and clinical research to offer an updated evaluation of the impact of cold exposure on these acute chest pain-related life-threatening CVDs. The evidence consistently demonstrates that cold weather significantly increases the incidence of such events, often with delayed effects lasting several days to weeks. Vulnerable groups, including the elderly, individuals with chronic conditions, and those of lower socioeconomic status, are particularly at risk. Data also suggest that interventions, including central heating, integrated health warning systems, and appropriate personal protective measures, can effectively mitigate the associated risks. Based on this evidence, the statement provides expert consensus recommendations across clinical, policy, and behavioral domains. Strengthening prevention and response to cold-related cardiovascular risks is essential for building climate-resilient health systems and mitigating the health impacts of climate change.

To elucidate the variance in the correlation between PM2.5 and O3 concentrations and their influencing factors in the southern Sichuan region, we conducted an analysis of PM2.5 concentrations in the cities of Yibin, Luzhou, Zigong, and Neijiang across different seasons in 2021. This analysis was juxtaposed with the daily maximum 8-hour average of O3 (MDA8 O3) and the atmospheric total oxidant concentration Ox (O3 + NO2). Augmenting this with reanalyzed data on the primary chemical constituents of PM2.5, we further explored the key chemical components predominantly influencing the correlations between PM2.5-O3 and PM2.5-Ox. Additionally, we elucidated the influence of meteorological conditions on these relationships using meteorological data. Our findings indicate that PM2.5 concentrations in the four cities exhibited a consistent seasonal trend, peaking in winter and reaching their lowest levels in summer, whereas O3 and Ox displayed an inverse trend compared to PM2.5. Organic matter (OM) and nitrate (NO3–) constituted the primary components of PM2.5. Except for autumn, positive correlations between PM2.5 and O3 were observed in each city across the seasons, with the strongest positive correlation manifesting during summer. Notably, OM and sulfate (SO42–) were dominant chemical components during summer, while NO3– and ammonium (NH4+) were influential in autumn, and OM in spring and winter, impacting the PM2.5-O3 correlations. Comparatively, PM2.5-Ox exhibited notably stronger positive correlations, particularly prominent in winter. Correlation coefficients between the main chemical components and Ox surpassed those with O3, indicating that atmospheric oxidation more effectively stimulated secondary components in PM2.5. The dominant chemical components across all seasons were similar to those observed in the PM2.5-O3 relationship. Meteorological conditions primarily weakened the positive synergistic relationships between PM2.5-O3 and PM2.5-Ox. Temperature (T) emerged as the dominant factor in spring, summer, and autumn, attenuating these correlations, while humidity (RH) dominated in winter.

Seasonal migration among retired individuals is increasingly common in China. Many seasonal retired migrants move to Hainan Island during the winter months and return to their original places in the warmer months. This study examines the changes in the health-related quality of life (HRQoL) among seasonal retired migrants during their migration and identifies potential effect modifiers of these changes. A prospective cohort study with one-year follow-up was conducted in Wuzhishan City, Hainan, involving 884 seasonal retired migrants who completed baseline and two follow-up investigations. HRQoL was measured using the EQ-5D-5L instrument. Fractional regression models were employed to analyze HRQoL changes and explore effect modifications by demographic, behavioral, and other health-related characteristics. The median age was 68 years, with 58.3

Climate change poses unprecedented challenges and threats to human health. Currently, research on the predicted health risks of different diseases caused by climate change is insufficient, especially in developing countries. We present a projection of temperature-related excess mortality associated with nonaccidental causes, cardiovascular, and respiratory disease in six Chinese cities (Harbin, Shenyang, Beijing, Chengdu, Shanghai, and Kunming) in different latitudinal zones using 10 global climate models (GCMs) under two alternative shared socioeconomic pathway (SSP) (SSP2-4.5 and SSP5-8.5) scenarios. The results suggested a consistent decreasing trend in cold-related excess mortality but a steep increase in heat-related excess mortality, with steeper gradients under the SSP5-8.5 scenario. The high rates of cold-related nonaccidental, cardiovascular, and respiratory mortality in the six cities are expected to decrease from 4.96 to 7.76 %, 9.97-12.39 %, and 6.13-11.47 %, respectively, in the 2010s to 1.88-5.53 %, 5.28-10.02 %, and 3.53-6.51 %, respectively, in the 2090s under the SSP5-8.5 scenario. Conversely, heat-related nonaccidental, cardiovascular, and respiratory mortality rates are currently low (0.18-2.07 %, 0.13-2.53 %, and 0.18-4.00 %, respectively), but is expected to increase considerably (3.10-7.28 %, 4.02-8.92 %, and 3.98-11.15 %, respectively) under the same scenario. Cardiovascular mortality exhibits a particularly strong response to climate change in terms of cause-specific mortality. Additionally, the impacts of climate change on the three mortality categories exhibited significant spatial heterogeneity. Compared with the 2010s, under the SSP5-8.5 scenario, the temperature-related net changes for the three categories of mortality in Kunming, a southern plateau city, are projected to decrease but increase in five other cities at different latitudes. Our findings suggest that mortality due to climate change varies widely according to cause of death and location. People with cardiovascular disease may be more susceptible. It is urgent to make more ambitious mitigation and adaptation strategies to minimize the public health impacts of climate change.

The adverse health effects of air pollution have long been a major public health concern. However, significant regional disparities exist in epidemiological findings. This study utilizes ambient air quality monitoring data and mortality records from a Basin City near the Qinghai-Tibet Plateau in 2023, applying the Generalized Additive Model to quantitatively assess the association between air pollution and mortality. The measurement record revealed that ozone concentrations exceeded the National Ambient Air Quality Standard II during more than 40

The mapping of emission inventory to the grids of the air quality model is a crucial pre-processing step in both atmospheric chemistry research and air quality forecasting. While some classic methods have been widely used for this mapping process, there is a lack of optimized methods that take into account the characteristics of the emission inventory and model grids. Inspired by the fact that the sum of the sub-areas of a unit cell is equal to 1, this paper introduces a novel method called “area-weight”, which simultaneously transfers and zooms the coordinates of the emission inventory and model grid nodes, then interpolates the emissions to the model grid nodes by considering the sub-areas of each unit cell as interpolation weights. Compared to the two classic methods, the area-weight method demonstrates its advantages in terms of both spatial smoothness and temporal efficiency. To assess the suitability of the area-weight method in practical applications, an emission inventory was mapped to the WRF-Chem model grid nodes to investigate the regional contribution of anthropogenic emissions to a PM2.5 pollution episode that occurred in Sichuan Basin, China. Through validation by observations, the feasibility of the area-weight method and WRF-Chem model configurations was confirmed. The model results indicate that emission reduction should be implemented especially in Chengdu Plain Economic Zone, because this region exhibits high PM2.5 contribution to the entire Sichuan Basin, especially to the southern Basin.

Extreme air temperature and increased weather oscillations caused by climate change have been threatening global health. Meteorological conditions are external inducers that may trigger the onset of gastrointestinal diseases,in addition to bacterial infection or behavioral factors including smoking,alcohol consumption,and hot food consumption[1,2].

Studying the formation and evolution mechanism of heavy pollution haze events is beneficial to con-trol the regional scale air quality and to formulate the prevention policies of severe haze pollution.Based on the WRF-CMAQ model and actual observation data,a severe haze event which occurred in Chengdu of Sichuan Ba-sin from December 23,2016 to January 7,2017 was reproduced.The distribution of temporal and spatial varia-tions of PM2.5 concentration and ventilation coefficient,the physical and chemical processes and the distribution of potential pollution source areas were analyzed to study the formation and evolution mechanism of this severe pollution haze event.Major results were as follows:(1)The environmental conditions of low temperature and low wind speed during the haze event created favorable conditions for the accumulation of pollutants.(2)The northerly airflow in the north of the basin,the southwesterly airflow in the south and the lower ventilation coeffi-cient value(weak turbulent diffusion capability of atmosphere)were the main reasons for the accumulation of pollutants.The PM2.5 concentration in Chengdu reached the peak under the influence of the northeast airflow.The dissipation of pollutants was mainly because of the strengthening of the northerly airflow and the higher ventila-tion coefficient value(strong turbulent diffusion capability of atmosphere).(3)The positive contribution of the aerosol process and emission sources in this haze event was strengthened.And the increase in PM2.5 was mainly at night(the negative contribution of the advection process and the weak diffusion process)and the magnitude of the increase was greater relative to the decrease,resulting in an overall gradual increase in PM2.5.(4)PSCF and CWT analysis showed that the airflows with high PM2.5 concentration in Chengdu mainly came from its northeast and southwest directions during this haze event,and the potential pollution source areas were generally distribut-ed in a northeast-southwest band.

Significant epidemiological research has revealed that exposure to air pollution is substantially associated with numerous detrimental health consequences [1-3] .The negative health effects of individual air pollutants (e.g.,fine particulate matter:PM 2.5 ;nitrogen dioxide:NO 2 ;carbon monoxide,CO;or ozone:O 3 ) have been widely explored [4] .However,humans are constantly exposed to multipollutant mixtures in real life,and biological responses to inhaled pollutants are likely to depend on the interplay of pollutant mixtures.Therefore,it is critical and imperative to explore the joint effects of multipollutant mixtures on human beings.

Nitrate and organic matters (OM) have become dominant components in fine particles (PM2.5) during winter haze in recent years. Based on continuous observations of gaseous pollutants, the chemical composition of PM2.5, and other relevant data collected over a one-month period (December 1-31, 2021), we investigated the main controlling factors contributing to the formation of wintertime haze in Yibin, located in the southern Sichuan Basin. Our observations reveal that two major haze episodes occurred during the campaign. Nitrate and OM were the dominant components in PM2.5, with an overall contribution of more than 50%. Nitrate and OM concentrations nearly quadrupled and more than tripled, respectively, from the non-pollution phase to the pollution phase. Furthermore, the mixing ratios of high-activity VOCs also noticeably increased during the pollution period, particularly OVOCs mixing ratios increased by 123.83%. PM2.5 concentrations were positively correlated with O-x concentrations, with a stronger relationship observed when O-x concentrations exceeded 80 mu g m(-3). There were also significant positive correlations between nitrate and O-x concentrations, as well as between OVOCs and OM concentrations. Furthermore, the pollution period showed a much higher degree of photochemical aging compared to the non-pollution period. Potential Source Contribution Function (PSCF) analysis revealed that, in addition to local emissions, regional transport, particularly air pollutants from Chengdu and Chongqing, significantly contributed to winter haze in Yibin. Our findings suggest that intense atmospheric photochemical oxidation and pronounced photochemistry contributed greatly to the occurrence of severe winter haze events.

In recent years, PM2.5 and O3 have been the two main pollutants affecting public health in China, but the interaction of the two pollutants on human health remains unclear. A two-stage analytical approach was used to investigate the relationships of PM2.5–O3 co-pollution with nonaccidental, cardiovascular, and respiratory mortality levels across 14 cities in China. We first utilized a generalized additive model (GAM) to determine the city-specific associations of PM2.5 and O3 with daily mortality. The associations were then combined at the national and regional levels using meta-analysis. To investigate the potential interactions between the two pollutants and cause-specific mortality, we performed stratified analyses by co-pollutant exposure levels and the synergy index (SI) (SI > 1 indicates a synergistic interaction). The effect of changes in the two pollutants’ concentrations (in 10 μg/m3 increases) on mortality was assessed. The stratification analysis results suggested that each 10 μg/m3 increase in PM2.5 at lag0-1 (lag01) in the low, moderate, and high strata of the O3 concentrations increased nonaccidental mortality by 0.07% (95% confidence interval: −0.03%, 0.17%), 0.33% (0.13%, 0.53%), and 0.68% (0.30%, 1.06%), respectively, with significant between-group differences (p < 0.001). Moreover, each 10 μg/m3 increase in O3 (lag01) in the low, moderate, and high strata of the PM2.5 concentrations increased nonaccidental mortality by 0.15% (−0.06%, 0.36%), 0.53% (0.19%, 0.87%), and 0.75% (0.14%, 1.36%), respectively, with significant between-group differences (p < 0.001). We also found substantial synergistic interactions between the two pollutants and nonaccidental, cardiovascular, and respiratory mortality levels, with SI values of 1.48, 1.51, and 1.33, respectively. Additionally, a subgroup analysis revealed that the interaction of these two pollutants on nonaccidental mortality were greater in South China compared to elsewhere, and during the warm season compared to during the cold season. Our findings suggested that the simultaneous control of PM2.5 and O3 within the context of combined air pollution could significantly decrease the disease risk, especially in southern China and during the warm season.

为进一步研究四川盆地冷锋特征及其影响,利用2015-2019年历史天气图、地面和高空气象观测以及大气环境监测数据,对四川盆地冷锋特征及其对逆温和大气污染的影响进行分析和讨论.结果表明,四川盆地冷锋过程年均9.6例,春秋季最多、最强.偏北路径冷锋最多、平均强度最强,春秋季最多;西北路径冷锋个例数和平均强度次之,夏多冬少;偏东路径冷锋最少、最弱.冷锋过境时逆温频率降低,过境后回升.冷锋过境对PM2.5、PM10、SO2、NO2、CO以清除为主,对颗粒物的影响高于气态污染物,而O3浓度随冷锋过境有增加趋势,强冷锋清除效果高于一般冷锋.过境时,西北路径冷锋的清除效果最好,PM2.5浓度降低近一半,而偏东路径冷锋清除能力最弱.冷锋过境后,偏北路径冷锋的清除作用依然显著,污染物浓度持续降低.

A climatology,which includes interannual variability,annual and diurnal cycles,intensities ac-cording to the"Enhanced Fujita Scale",geographic distribution,and environmental conditions derived from reanalysis data,is developed in this study for the tornadoes in Liaoning Province during 1971-2020 in order to understand the climatic characteristics of tornado.The tornado reports are obtained from the Chinese Meteorological Disaster Dictionary,Chinese Meteorological Disaster Yearbook and other associated data.The differences in environmental background between Liaoning Province in China and the tornado-prone areas in United States are compared,and the typical circulation conditions and atmospheric charac-teristics of Liaoning tornadoes are analyzed.The major findings are as follows.Over the 50 years(1971-2020),there were 105 tornadoes recorded(including 17 EF2 or stronger tornadoes)in 97 tornadic days in Liaoning Province,which suggests that Liaoning has 2.1 tornadoes per year with the annual generation density to be 1.4X10-5 km-2,approximately equal to 1/10 tornadoes in the United States.A total of 17 EF2 or stronger tornadoes are recorded,with an average annual occurrence of 0.3.The tornadoes occur mostly(95％)from May through September,and 67％of tornado genesis are between 14:00 BT and 19:00 BT.Significant tornadoes(EF2/EF3/EF4)mainly occur in the central and western part of Liao-ning,while weak tornadoes(EF0/EF1)happen more in the coastal region of the southeastern Liaoning.The tornadic season in the northwest of Liaoning is much earlier than in the southeast.CAPE and mid-level wind shear often change in opposite phases with seasons,and the appropriate configuration of the two is the prerequisite for the occurrence of tornadoes and other convective weather.Additionally,the lower low-level the storm relative helicity(SRH)is the major cause for the apparently lower tornado density in Lia-oning relative to the United States.About 87％of tornadoes are related to the cold vortices,which can be mainly divided into the short-wave trough category at the cold vortex bottom and cold vortex front category dominated by low-level frontogenesis(65％),the mid-level dry cold air forcing category dominated by mid-to-high level dry cold airflow(12％),and the cold vortex central area category dominated by mesoscale near-storm environment under severe thermal instability(6％).The environmental conditions in the high-incidence area of Liaoning tornadoes have the following characteristics:the mid-level impact system is cold vortex,the ground corresponds to frontal cyclones,tornadoes often appear in the northwest quadrant of the center of SRH and in the large-value zone of CAPE gradient,corresponding to the east side of cold front and the dry line at surface as well as the top of the temperature ridge.

Introduction In recent years, air pollution caused by co-occurring PM 2.5 and O 3 , named combined air pollution (CAP), has been observed in Beijing, China, although the health effects of CAP on population mortality are unclear. Methods We employed Poisson generalized additive models (GAMs) to evaluate the individual and joint effects of PM 2.5 and O 3 on mortality (nonaccidental, respiratory, and cardiovascular mortality) in Beijing, China, during the whole period (2014–2016) and the CAP period. Adverse health effects were assessed for percentage increases (%) in the three mortality categories with each 10-μg/m 3 increase in PM 2.5 and O 3 . The cumulative risk index ( CRI ) was adopted as a novel approach to quantify the joint effects. Results The results suggested that both PM 2.5 and O 3 exhibited the greatest individual effects on the three mortality categories with cumulative lag day 01. Increases in the nonaccidental, cardiovascular, and respiratory mortality categories were 0.32%, 0.36%, and 0.43% for PM 2.5 (lag day 01) and 0.22%, 0.37%, and 0.25% for O 3 (lag day 01), respectively. There were remarkably synergistic interactions between PM 2.5 and O 3 on the three mortality categories. The study showed that the combined effects of PM 2.5 and O 3 on nonaccidental, cardiovascular, and respiratory mortality were 0.34%, 0.43%, and 0.46%, respectively, during the whole period and 0.58%, 0.79%, and 0.75%, respectively, during the CAP period. Our findings suggest that combined exposure to PM 2.5 and O 3 , particularly during CAP periods, could further exacerbate their single-pollutant health risks. Conclusion These findings provide essential scientific evidence for the possible creation and implementation of environmental protection strategies by policymakers.

The adverse health effects of PM2.5 have been well demonstrated by many studies. However, as a component of PM2.5, evidence on the mortality risk of black carbon (BC) is still limited. In this study, based on the data of daily mean PM2.5 concentration, BC concentration, meteorological factors, total non-accidental (all-cause) and cardiovascular mortality in Shanghai and Nanjing during 2015-2016, a semi-parameter generalized additive model (GAM) in the time series and the constituent residual approach were employed to explore the exposure-response relationship between BC and human mortality in these two megacities of Yangtze River Delta, China. The main objective was to separate the health effects of BC from total PM2.5, and compare the difference of mortality ER related to BC original concentration and adjusted concentration after controlling PM2.5. Results showed that there were all significantly associated with daily mortality for PM2.5 and BC. The percentage excess risk (ER) increases in all-cause and cardiovascular categories were 1.68 % (95 % s 1.28, 2.08) and 2.16 % (95 % CI: 1.54, 2.79) with 1 μg/m3 increment in original BC concentration in Shanghai. And the ER in Nanjing was smaller than that in Shanghai. After eliminating PM2.5 confounding effects by a constituent residual approach, the BC residual concentration still had a strong significant ER. The ER for BC residual in Shanghai got an obvious increase, and ER of the cardiovascular mortality for all, females and males increased by 0.55 %, 1.46 % and 0.62 %, respectively, while the ER in Nanjing decreased slightly. It also revealed that females were more sensitive to the health risk associated with short-term BC exposure than males. Our findings provide additional important evidence and ER for mortality related to independent BC exposure. Therefore, BC emission reduction should be paid more attention in air pollution control strategies to reduce BC-related health burdens.

Air pollution was indicated to be a key factor contributing to the aggressive spread of influenza viruses, whereas uncertainty still exists regarding to whether distinctions exist between influenza subtypes. Our study quantified the impact of five air pollutants on influenza subtype outbreaks in Shenzhen, China, a densely populated and highly urbanized megacity. Daily influenza outbreak data of laboratory-confirmed positive cases were obtained from the Shenzhen CDC, from May 1, 2013 to Dec 31, 2015. Concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matters <= 2.5 mu m (PM2.5), particulate matters <= 10 mu m (PM10), and ozone (O3), were retrieved from the 18 national monitoring stations. The generalized additive model (GAM) and distributed lag non-linear model (DLNM) were used to calculate the concentration-response relationships between environ-mental inducers and outbreak epidemics, respectively for influenza A (Flu-A) and B (Flu-B). There were 1687 positive specimens were confirmed during the study period. The cold season was restricted from Nov. 4th to Apr. 20th, covering all seasons other than the long-lasting summer. Relatively heavy fine particle matter (PM2.5) and NO2 pollution was observed in cold months, with mean concentrations of 46.06 mu g/m3 and 40.03 mu g/m3, respectively. Time-series analysis indicated that high concentrations of NO2, PM2.5, PM10, and O3 were associated with more influenza outbreaks at short lag periods (0-5 d). Although more Flu-B (679 cases) epidemics occurred than Flu-A (382 cases) in the cold season, Flu-A generally showed higher susceptibility to air pollutants. A 10 mu g/ m3 increment in concentrations of PM2.5, PM10, and O3 at lag 04, was associated with a 2.103 (95%CI: 1.528-2.893), 1.618 (95%CI: 1.311-1.996), and 1.569 (95%CI: 1.214-2.028) of the relative risk (RR) of Flu-A, respectively. A 5 mu g/m3 increase in NO2 was associated with higher risk of Flu-A at lag 03 (RR = 1.646, 95%CI: 1.295-2.092) and of Flu-B at lag 04 (RR = 1.319, 95%CI: 1.095-1.588). Nevertheless, barely significant effect of particulate matters (PM2.5, PM10) on Flu-B and SO2 on both subtypes was detected. Further, the effect estimates of NO2 increased for both subtypes when coexisting with other pollutants. This study provides evidence that declining concentrations of main pollutants including NO2, O3, and particulate matters, could substantially decrease influenza risk in subtropical Shenzhen, especially for influenza A.

Epidemiology studies evaluating the health effect of the decarbonization policy in Beijing, China are limited. This time series study sought to examine the health effectiveness of BC and PM2.5 in Beijing, a formerly heavily polluted city. Therefore, the objectives of this article were (1) to evaluate the modification effects of temperature on the health effects of black carbon (BC) and fine particles (PM2.5) in Beijing. (2) to compare the health effects of BC and PM2.5 pre- and post-implementation of decarbonization policy. Bivariate Response Surface Model and Generalised Additive Model were used to analyze the modification effects. Comparison analysis was conducted pre- and post-implementation of decarbonization policy. The results indicated that (i) Post-implementation, reductions were noted in non-accidental diseases (RR = 1.064 per 10 & mu;g/m3), circulatory diseases (RR = 1.068 per 10 & mu;g/m3) and respiratory diseases (RR = 1.148 per 10 & mu;g/m3) related to BC; this was especially pronounced on cold days. (ii) Greater reductions in risk of non-accidental, circulatory and respiratory deaths (Dvalue: 0.134 versus 0.002, 0.180 versus 0.003, 0.176 versus 0.002) were noted for BC than for PM2.5. (iii) Higher risks of the impact of BC on respiratory diseases were observed in females than in males. In conclusion, a stronger correlation existed between BC and mortality on cold days than moderately cold days in Beijing. Furthermore, compared with PM2.5, BC posed a greater disease risk and the effectiveness of the decarbonization policy was more obvious.

为了解辽宁龙卷气候特征,基于《中国气象灾害大典》《中国气象灾害年鉴》和其他相关资料,根据"改进藤田分级"龙卷级别分类标准,对 1971-2020 年辽宁龙卷进行强度分类和时空分布特征统计,并对比我国辽宁与美国龙卷高发区环境背景差异,分析辽宁龙卷典型的环流形势、物理量特征.得到以下主要结论:1971-2020 年辽宁地区共记录到 97 个龙卷日发生龙卷 105 次,年均为 2.1 次,年平均龙卷生成密度为 1.4×10-5 个·km-2,约为美国的 1/10.EF2 及以上级别强龙卷共记录到17 次,年均出现 0.3 次.95%的龙卷出现在 5-9 月,67%出现在 14-19 时.EF2 及以上级别强龙卷主要分布在辽宁中部以西地区,东南沿海地区多为弱龙卷,辽宁西北部龙卷季明显早于东南部.对流有效位能和中低层风切变随季节呈反相位变化,两者的合适配置是龙卷等强对流天气产生的前提条件.低层风暴相对螺旋度偏小是我国辽宁较美国龙卷高发区龙卷密度明显偏小的主要原因.辽宁 87%的龙卷与冷涡相关,分为低层锋生主导的冷涡底部短波槽和冷涡前部型(65%)、中高空干冷气流主导的冷涡后部型(12%)以及强热力不稳定条件下中尺度近风暴环境主导的冷涡主体型(6%).辽宁龙卷高发区典型环境条件具有以下特征:中层影响系统为冷涡,地面对应锋面气旋;龙卷常出现于低层风暴相对螺旋度中心偏西北象限,对流有效位能梯度大值区内,对应地面冷锋和干线的东侧、温度脊顶部.