Pub Date : 2024-06-28DOI: 10.5194/acp-24-7405-2024
Mona Zolghadrshojaee, Susann Tegtmeier, Sean M. Davis, Robin Pilch Kedzierski
Abstract. The tropical tropopause layer (TTL) is the main gateway for air transiting from the troposphere to the stratosphere and therefore impacts the chemical composition of the stratosphere. In particular, the cold-point tropopause, where air parcels encounter their final dehydration, effectively controls the water vapor content of the lower stratosphere. Given the important role of stratospheric water vapor for the global energy budget, it is crucial to understand the long-term changes in cold-point temperature and their impact on water vapor trends. Our study uses Global Navigation Satellite System – Radio Occultation (GNSS-RO) data to show that there has been no overall cooling trend of the TTL over the past 2 decades, in contrast to observations prior to 2000. Instead, the cold point is warming, with the strongest trends of up to 0.7 K per decade during boreal winter and spring. The cold-point warming shows longitudinal asymmetries, with the smallest warming over the central Pacific and the largest warming over the Atlantic. These asymmetries are anticorrelated with patterns of tropospheric temperature trends, and regions of strongest cold-point warming are found to show slight cooling trends in the upper troposphere. Overall, the here-identified warming of the cold point is consistent with model predictions under global climate change, which attribute the warming trends to radiative effects. The seasonal signals and zonal asymmetries of the cold-point temperature and height trends might be related to dynamical responses to enhanced upper-tropospheric heating, changing convection, or trends in the stratospheric circulation. Water vapor observations in the TTL show mostly positive trends consistent with cold-point warming for 2004–2021. We find a decrease in the amplitude of the cold-point temperature seasonal cycle by ∼ 7 % driving a reduction in the seasonal cycle in 100 hPa water vapor by 5 %–6 %. Our analysis shows that this reduction in the seasonal cycle is transported upwards together with the seasonal anomalies and has reduced the amplitude of the well-known tape recorder over the last 2 decades.
{"title":"Variability and long-term changes in tropical cold-point temperature and water vapor","authors":"Mona Zolghadrshojaee, Susann Tegtmeier, Sean M. Davis, Robin Pilch Kedzierski","doi":"10.5194/acp-24-7405-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7405-2024","url":null,"abstract":"Abstract. The tropical tropopause layer (TTL) is the main gateway for air transiting from the troposphere to the stratosphere and therefore impacts the chemical composition of the stratosphere. In particular, the cold-point tropopause, where air parcels encounter their final dehydration, effectively controls the water vapor content of the lower stratosphere. Given the important role of stratospheric water vapor for the global energy budget, it is crucial to understand the long-term changes in cold-point temperature and their impact on water vapor trends. Our study uses Global Navigation Satellite System – Radio Occultation (GNSS-RO) data to show that there has been no overall cooling trend of the TTL over the past 2 decades, in contrast to observations prior to 2000. Instead, the cold point is warming, with the strongest trends of up to 0.7 K per decade during boreal winter and spring. The cold-point warming shows longitudinal asymmetries, with the smallest warming over the central Pacific and the largest warming over the Atlantic. These asymmetries are anticorrelated with patterns of tropospheric temperature trends, and regions of strongest cold-point warming are found to show slight cooling trends in the upper troposphere. Overall, the here-identified warming of the cold point is consistent with model predictions under global climate change, which attribute the warming trends to radiative effects. The seasonal signals and zonal asymmetries of the cold-point temperature and height trends might be related to dynamical responses to enhanced upper-tropospheric heating, changing convection, or trends in the stratospheric circulation. Water vapor observations in the TTL show mostly positive trends consistent with cold-point warming for 2004–2021. We find a decrease in the amplitude of the cold-point temperature seasonal cycle by ∼ 7 % driving a reduction in the seasonal cycle in 100 hPa water vapor by 5 %–6 %. Our analysis shows that this reduction in the seasonal cycle is transported upwards together with the seasonal anomalies and has reduced the amplitude of the well-known tape recorder over the last 2 decades.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-28DOI: 10.5194/acp-24-7421-2024
Qianqian Song, Paul Ginoux, María Gonçalves Ageitos, Ron L. Miller, Vincenzo Obiso, Carlos Pérez García-Pando
Abstract. Mineralogical composition drives dust impacts on Earth's climate systems. However, most climate models still use homogeneous dust, without accounting for the temporal and spatial variation in mineralogy. To quantify the radiative impact of resolving dust mineralogy on Earth's climate, we implement and simulate the distribution of dust minerals (i.e., illite, kaolinite, smectite, hematite, calcite, feldspar, quartz, and gypsum) from Claquin et al. (1999) (C1999) and activate their interaction with radiation in the GFDL AM4.0 model. Resolving mineralogy reduces dust absorption compared to the homogeneous dust used in the standard GFDL AM4.0 model that assumes a globally uniform hematite volume content of 2.7 % (HD27). The reduction in dust absorption results in improved agreement with observation-based single-scattering albedo (SSA), radiative fluxes from CERES (the Clouds and the Earth's Radiant Energy System), and land surface temperature from the CRU (Climatic Research Unit) compared to the baseline HD27 model version. It also results in distinct radiative impacts on Earth's climate over North Africa. Over the 19-year (from 2001 to 2019) modeled period during JJA (June–July–August), the reduction in dust absorption in AM4.0 leads to a reduction of over 50 % in net downward radiation across the Sahara and approximately 20 % over the Sahel at the top of the atmosphere (TOA) compared to the baseline HD27 model version. The reduced dust absorption weakens the atmospheric warming effect of dust aerosols and leads to an alteration in land surface temperature, resulting in a decrease of 0.66 K over the Sahara and an increase of 0.7 K over the Sahel. The less warming in the atmosphere suppresses ascent and weakens the monsoon inflow from the Gulf of Guinea. This brings less moisture to the Sahel, which combined with decreased ascent induces a reduction of precipitation. To isolate the effect of reduced absorption compared to resolving spatial and temporal mineralogy, we carry out a simulation where the hematite volume content of homogeneous dust is reduced from 2.7 % to 0.9 % (HD09). The dust absorption (e.g., single-scattering albedo) of HD09 is comparable to that of the mineralogically speciated model on a global mean scale, albeit with a lower spatial variation that arises solely from particle size. Comparison of the two models indicates that the spatial inhomogeneity in dust absorption resulting from resolving mineralogy does not have significant impacts on Earth's radiation and climate, provided there is a similar level of dust absorption on a global mean scale before and after resolving dust mineralogy. However, uncertainties related to emission and distribution of minerals may blur the advantages of resolving minerals to study their impact on radiation, cloud properties, ocean biogeochemistry, air quality, and photochemistry. On the other hand, lumping together clay minerals (i.e., illite, kaolinite, and smectite), but excluding externa
{"title":"Modeling impacts of dust mineralogy on fast climate response","authors":"Qianqian Song, Paul Ginoux, María Gonçalves Ageitos, Ron L. Miller, Vincenzo Obiso, Carlos Pérez García-Pando","doi":"10.5194/acp-24-7421-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7421-2024","url":null,"abstract":"Abstract. Mineralogical composition drives dust impacts on Earth's climate systems. However, most climate models still use homogeneous dust, without accounting for the temporal and spatial variation in mineralogy. To quantify the radiative impact of resolving dust mineralogy on Earth's climate, we implement and simulate the distribution of dust minerals (i.e., illite, kaolinite, smectite, hematite, calcite, feldspar, quartz, and gypsum) from Claquin et al. (1999) (C1999) and activate their interaction with radiation in the GFDL AM4.0 model. Resolving mineralogy reduces dust absorption compared to the homogeneous dust used in the standard GFDL AM4.0 model that assumes a globally uniform hematite volume content of 2.7 % (HD27). The reduction in dust absorption results in improved agreement with observation-based single-scattering albedo (SSA), radiative fluxes from CERES (the Clouds and the Earth's Radiant Energy System), and land surface temperature from the CRU (Climatic Research Unit) compared to the baseline HD27 model version. It also results in distinct radiative impacts on Earth's climate over North Africa. Over the 19-year (from 2001 to 2019) modeled period during JJA (June–July–August), the reduction in dust absorption in AM4.0 leads to a reduction of over 50 % in net downward radiation across the Sahara and approximately 20 % over the Sahel at the top of the atmosphere (TOA) compared to the baseline HD27 model version. The reduced dust absorption weakens the atmospheric warming effect of dust aerosols and leads to an alteration in land surface temperature, resulting in a decrease of 0.66 K over the Sahara and an increase of 0.7 K over the Sahel. The less warming in the atmosphere suppresses ascent and weakens the monsoon inflow from the Gulf of Guinea. This brings less moisture to the Sahel, which combined with decreased ascent induces a reduction of precipitation. To isolate the effect of reduced absorption compared to resolving spatial and temporal mineralogy, we carry out a simulation where the hematite volume content of homogeneous dust is reduced from 2.7 % to 0.9 % (HD09). The dust absorption (e.g., single-scattering albedo) of HD09 is comparable to that of the mineralogically speciated model on a global mean scale, albeit with a lower spatial variation that arises solely from particle size. Comparison of the two models indicates that the spatial inhomogeneity in dust absorption resulting from resolving mineralogy does not have significant impacts on Earth's radiation and climate, provided there is a similar level of dust absorption on a global mean scale before and after resolving dust mineralogy. However, uncertainties related to emission and distribution of minerals may blur the advantages of resolving minerals to study their impact on radiation, cloud properties, ocean biogeochemistry, air quality, and photochemistry. On the other hand, lumping together clay minerals (i.e., illite, kaolinite, and smectite), but excluding externa","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/acp-24-7359-2024
Barbara Dietel, Odran Sourdeval, Corinna Hoose
Abstract. The thermodynamic phase of clouds in low and middle levels over the Southern Ocean and the Arctic marine regions is poorly known, leading to uncertainties in the radiation budget in weather and climate models. To improve the knowledge of the cloud phase, we analyse 2 years of the raDAR-liDAR (DARDAR) dataset based on active satellite instruments. We classify clouds according to their base and top height and focus on low-, mid-, and mid- to low-level clouds as they are the most frequent in the mixed-phase temperature regime. Low-level single-layer clouds occur in 8 %–15 % of all profiles, but single-layer clouds spanning the mid-level also amount to approx. 15 %. Liquid clouds show mainly a smaller vertical extent but a horizontally larger extent compared to ice clouds. The results show the highest liquid fractions for low-level and mid-level clouds. Two local minima in the liquid fraction are observed around cloud top temperatures of −15 and −5 °C. Mid-level and mid- to low-level clouds over the Southern Ocean and low-level clouds in both polar regions show higher liquid fractions if they occur over sea ice compared to the open ocean. Low-level clouds and mid- to low-level clouds with high sea salt concentrations, used as a proxy for sea spray, show reduced liquid fractions. In mid-level clouds, dust shows the largest correlations with liquid fraction, with a lower liquid fraction for a higher dust aerosol concentration. Low-level clouds clearly show the largest contribution to the shortwave cloud radiative effect in both polar regions, followed by mid- to low-level clouds.
{"title":"Characterisation of low-base and mid-base clouds and their thermodynamic phase over the Southern Ocean and Arctic marine regions","authors":"Barbara Dietel, Odran Sourdeval, Corinna Hoose","doi":"10.5194/acp-24-7359-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7359-2024","url":null,"abstract":"Abstract. The thermodynamic phase of clouds in low and middle levels over the Southern Ocean and the Arctic marine regions is poorly known, leading to uncertainties in the radiation budget in weather and climate models. To improve the knowledge of the cloud phase, we analyse 2 years of the raDAR-liDAR (DARDAR) dataset based on active satellite instruments. We classify clouds according to their base and top height and focus on low-, mid-, and mid- to low-level clouds as they are the most frequent in the mixed-phase temperature regime. Low-level single-layer clouds occur in 8 %–15 % of all profiles, but single-layer clouds spanning the mid-level also amount to approx. 15 %. Liquid clouds show mainly a smaller vertical extent but a horizontally larger extent compared to ice clouds. The results show the highest liquid fractions for low-level and mid-level clouds. Two local minima in the liquid fraction are observed around cloud top temperatures of −15 and −5 °C. Mid-level and mid- to low-level clouds over the Southern Ocean and low-level clouds in both polar regions show higher liquid fractions if they occur over sea ice compared to the open ocean. Low-level clouds and mid- to low-level clouds with high sea salt concentrations, used as a proxy for sea spray, show reduced liquid fractions. In mid-level clouds, dust shows the largest correlations with liquid fraction, with a lower liquid fraction for a higher dust aerosol concentration. Low-level clouds clearly show the largest contribution to the shortwave cloud radiative effect in both polar regions, followed by mid- to low-level clouds.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/egusphere-2024-1684
Xuehong Gong, Zeyu Liu, Jie Tian, Qiyuan Wang, Guohui Li, Zhisheng An, Yongming Han
Abstract. Wildfires release large amounts of greenhouse gases into the atmosphere, exacerbating climate change and causing severe impacts on air quality and human health. Including carbon dioxide (CO2) emissions from wildfires in international assessments and national emission reduction responsibilities is crucial for global carbon reduction and environmental governance. In this study, based on a bottom-up approach and using satellite data, combined with emission factor and aboveground biomass data for different vegetation cover types (forest, shrub, grassland, cropland), the dynamic changes in CO2 emissions from wildfires in China from 2001 to 2022 were analyzed. The results showed that between 2001 and 2022, the total CO2 emissions from wildfires in China were 693.7 Tg (1 Tg = 1012 g), with an annual average of 31.5 Tg. The CO2 emissions from cropland and forest fires were relatively high, accounting for 46 % and 32 %, respectively. The yearly variation in CO2 emissions from forest and shrub fires showed a significant downward trend, while emissions from grassland fires remained relatively stable. In contrast, the CO2 emissions from cropland fires showed a clear upward trend. High CO2 emissions from wildfires were mainly concentrated in the eastern regions of Heilongjiang and Inner Mongolia Provinces in China, accounting for 44 % of the total annual emissions. Various factors such as daily cumulative sunshine hours (Spearman’s correlation coefficient, forest: -0.41, shrub:0.25; p < 0.001) and the normalized difference vegetation index (NDVI; Spearman’s correlation coefficient, forest: -0.35, shrub: 0.37; p < 0.001), influenced CO2 emissions from forest and shrub fires. Moreover, temperature (Spearman’s correlation coefficient, -0.45, p < 0.001) primarily affected CO2 emissions from grassland fires. The CO2 emissions from cropland fires negatively correlated with the gross domestic product (GDP) (Spearman’s correlation coefficient, -0.52, p < 0.001) and population density (Spearman’s correlation coefficient, -0.51, p < 0.001). China's policy management has been crucial in reducing CO2 emissions from wildfires. By accurately assessing CO2 emissions from wildfires, governments worldwide can better set CO2 reduction targets, take corresponding measures, and contribute to the global response to climate change.
{"title":"Global carbon emission accounting: national-level assessment of wildfire CO2 emission – a case study of China","authors":"Xuehong Gong, Zeyu Liu, Jie Tian, Qiyuan Wang, Guohui Li, Zhisheng An, Yongming Han","doi":"10.5194/egusphere-2024-1684","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1684","url":null,"abstract":"<strong>Abstract.</strong> Wildfires release large amounts of greenhouse gases into the atmosphere, exacerbating climate change and causing severe impacts on air quality and human health. Including carbon dioxide (CO<sub>2</sub>) emissions from wildfires in international assessments and national emission reduction responsibilities is crucial for global carbon reduction and environmental governance. In this study, based on a bottom-up approach and using satellite data, combined with emission factor and aboveground biomass data for different vegetation cover types (forest, shrub, grassland, cropland), the dynamic changes in CO<sub>2</sub> emissions from wildfires in China from 2001 to 2022 were analyzed. The results showed that between 2001 and 2022, the total CO<sub>2</sub> emissions from wildfires in China were 693.7 Tg (1 Tg = 10<sup>12</sup> g), with an annual average of 31.5 Tg. The CO<sub>2</sub> emissions from cropland and forest fires were relatively high, accounting for 46 % and 32 %, respectively. The yearly variation in CO<sub>2</sub> emissions from forest and shrub fires showed a significant downward trend, while emissions from grassland fires remained relatively stable. In contrast, the CO<sub>2</sub> emissions from cropland fires showed a clear upward trend. High CO<sub>2</sub> emissions from wildfires were mainly concentrated in the eastern regions of Heilongjiang and Inner Mongolia Provinces in China, accounting for 44 % of the total annual emissions. Various factors such as daily cumulative sunshine hours (Spearman’s correlation coefficient, forest: -0.41, shrub:0.25; p < 0.001) and the normalized difference vegetation index (NDVI; Spearman’s correlation coefficient, forest: -0.35, shrub: 0.37; p < 0.001), influenced CO<sub>2</sub> emissions from forest and shrub fires. Moreover, temperature (Spearman’s correlation coefficient, -0.45, p < 0.001) primarily affected CO<sub>2</sub> emissions from grassland fires. The CO<sub>2</sub> emissions from cropland fires negatively correlated with the gross domestic product (GDP) (Spearman’s correlation coefficient, -0.52, p < 0.001) and population density (Spearman’s correlation coefficient, -0.51, p < 0.001). China's policy management has been crucial in reducing CO<sub>2</sub> emissions from wildfires. By accurately assessing CO<sub>2</sub> emissions from wildfires, governments worldwide can better set CO<sub>2</sub> reduction targets, take corresponding measures, and contribute to the global response to climate change.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/egusphere-2024-1808
Christian Mark Garcia Salvador, Jeffrey D. Wood, Emma Grace Cochran, Hunter A. Seubert, Bella D. Kamplain, Sam S. Overby, Kevin R. Birdwell, Lianhong Gu, Melanie A. Mayes
Abstract. Climate extremes are projected to cause unprecedented deviations in the emission and transformation of volatile organic compounds (VOCs), which trigger feedback mechanisms that will impact the atmospheric oxidation and formation of aerosols and clouds. However, the response of VOCs to future conditions such as extreme heat and wildfire events is still uncertain. This study explored the modification of the mixing ratio and distribution of several anthropogenic and biogenic VOCs in a temperate oak–hickory–juniper forest as a response to increased temperature and transported biomass burning plumes. A chemical ionization mass spectrometer was deployed on a tower at a height of 32 m in rural central Missouri, United States, for the continuous and in situ measurement of VOCs from June to August of 2023. The maximum observed temperature in the region was 38 °C, and during multiple episodes the temperature remained above 32 °C for several hours. Biogenic VOCs such as isoprene and monoterpene followed closely the temperature daily profile but at varying rates, whereas anthropogenic VOCs were insensitive to elevated temperature. During the measurement period, wildfire emissions were transported to the site and substantially increased the mixing ratios of acetonitrile and benzene, which are produced from burning of biomass. An in-depth analysis of the mass spectra revealed more than 250 minor compounds, such as formamide and methylglyoxal. The overall volatility, O:C, and H:C ratios of the extended list of VOCs responded to the changes in extreme heat and the presence of combustion plumes. Multivariate analysis also clustered the compounds into five factors, which highlighted the sources of the unaccounted-for VOCs. Overall, results here underscore the imminent effect of extreme heat and wildfire on VOC variability, which is important in understanding future interactions between climate and atmospheric chemistry.
{"title":"Extreme Heat and Wildfire Emissions Enhance Volatile Organic Compounds: Insights on Future Climate","authors":"Christian Mark Garcia Salvador, Jeffrey D. Wood, Emma Grace Cochran, Hunter A. Seubert, Bella D. Kamplain, Sam S. Overby, Kevin R. Birdwell, Lianhong Gu, Melanie A. Mayes","doi":"10.5194/egusphere-2024-1808","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1808","url":null,"abstract":"<strong>Abstract.</strong> Climate extremes are projected to cause unprecedented deviations in the emission and transformation of volatile organic compounds (VOCs), which trigger feedback mechanisms that will impact the atmospheric oxidation and formation of aerosols and clouds. However, the response of VOCs to future conditions such as extreme heat and wildfire events is still uncertain. This study explored the modification of the mixing ratio and distribution of several anthropogenic and biogenic VOCs in a temperate oak–hickory–juniper forest as a response to increased temperature and transported biomass burning plumes. A chemical ionization mass spectrometer was deployed on a tower at a height of 32 m in rural central Missouri, United States, for the continuous and in situ measurement of VOCs from June to August of 2023. The maximum observed temperature in the region was 38 °C, and during multiple episodes the temperature remained above 32 °C for several hours. Biogenic VOCs such as isoprene and monoterpene followed closely the temperature daily profile but at varying rates, whereas anthropogenic VOCs were insensitive to elevated temperature. During the measurement period, wildfire emissions were transported to the site and substantially increased the mixing ratios of acetonitrile and benzene, which are produced from burning of biomass. An in-depth analysis of the mass spectra revealed more than 250 minor compounds, such as formamide and methylglyoxal. The overall volatility, O:C, and H:C ratios of the extended list of VOCs responded to the changes in extreme heat and the presence of combustion plumes. Multivariate analysis also clustered the compounds into five factors, which highlighted the sources of the unaccounted-for VOCs. Overall, results here underscore the imminent effect of extreme heat and wildfire on VOC variability, which is important in understanding future interactions between climate and atmospheric chemistry.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/egusphere-2024-1891
Luís Filipe Escusa dos Santos, Hannah C. Frostenberg, Alejandro Baró Pérez, Annica M. L. Ekman, Luisa Ickes, Erik S. Thomson
Abstract. Increased surface warming over the Arctic, triggered by increased greenhouse gas concentrations and feedback processes in the climate system, has been causing a steady decline in sea-ice extent and thickness. With the retreating sea-ice, shipping activity will likely increase in the future driven by economic activity and the potential for realizing time and fuel savings from transiting shorter trade routes. Moreover, over the last decade, the global shipping sector has been subject to regulatory changes, that affect the physicochemical properties of exhaust particles. International regulations aiming to reduce SOx and particulate matter (PM) emissions, mandate ships to burn fuels with reduced sulfur content or alternatively, use wet scrubbing as exhaust after-treatment when using fuels with sulfur contents exceeding regulatory limits. Compliance measures affect the physicochemical properties of exhaust particles and their cloud condensation nuclei (CCN) activity in different ways, with the potential to have both direct and indirect impacts on atmospheric processes such as the formation and lifetime of clouds. Given the relatively pristine Arctic environment, ship exhaust particle emissions could be a large perturbation to natural baseline Arctic aerosol concentrations. Low-level stratiform mixed-phase clouds cover large areas of the Arctic region and play an important role in the regional energy budget. Results from laboratory marine engine measurements, which investigated the impact of fuel sulfur content (FSC) reduction and wet scrubbing on exhaust particle properties, motivate the use of large eddy simulations to further investigate how such particles may influence the micro- and macrophysical properties of a stratiform mixed-phase cloud case observed during the Arctic Summer Cloud Ocean Study campaign. Simulated enhancements of ship exhaust particles predominantly affected the liquid-phase properties of the cloud and led to a decrease in liquid surface precipitation, increased cloud albedo and increased longwave surface warming. The magnitude of the impact strongly depended on ship exhaust particle concentration, hygroscopicity, and size where the effect of particle size dominated the impact of hygroscopicity. While low FSC exhaust particles were mostly observed to affect cloud properties at exhaust particle concentrations of 1000 cm-3, exhaust wet scrubbing already led to significant changes at concentrations of 100 cm-3. Additional simulations with cloud ice water path increased from ≈5.5 g m-2 to ≈9.3 g m-2, show more muted responses to ship exhaust perturbations but revealed that exhaust perturbations may even lead to a slight radiative cooling effect depending on the microphysical state of the cloud. The regional impact of shipping activity on Arctic cloud properties may, therefore, strongly depend on ship fuel type, whether ships utilize wet scrubbers, and
摘要由于温室气体浓度增加和气候系统中的反馈过程，北极地区地表变暖，导致海冰范围和厚度持续下降。随着海冰的消退，未来航运活动很可能会在经济活动的推动下增加，而且通过更短的贸易航线可以节省时间和燃料。此外，在过去的十年中，全球航运业一直受到法规变化的影响，从而影响到废气颗粒的物理化学特性。旨在减少硫氧化物和微粒物质（PM）排放的国际法规要求船舶燃烧硫含量较低的燃料，或者在使用硫含量超过法规限制的燃料时使用湿式洗涤作为尾气后处理。合规措施会以不同的方式影响废气颗粒的物理化学特性及其云凝结核 (CCN) 活性，有可能对云的形成和寿命等大气过程产生直接和间接影响。鉴于北极环境相对原始，船舶废气颗粒排放可能会对北极气溶胶的自然基线浓度造成巨大干扰。低层平流混合相云覆盖了北极地区的大片区域，在区域能量预算中发挥着重要作用。实验室船用发动机测量的结果研究了降低燃料硫含量（FSC）和湿式洗涤对废气颗粒特性的影响，这促使我们使用大涡模拟来进一步研究这些颗粒如何影响在北极夏季云海研究活动中观测到的平流混合相云的微观和宏观物理特性。模拟的船舶废气颗粒增强主要影响了云的液相特性，导致液面降水减少、云反照率增加和长波表面增温。影响的大小在很大程度上取决于船舶废气颗粒的浓度、吸湿性和大小，其中颗粒大小的影响在吸湿性的影响中占主导地位。虽然在废气颗粒浓度为 1000 cm-3 时，观察到低 FSC 废气颗粒对云特性的影响最大，但在浓度为 100 cm-3 时，废气湿式洗涤已经导致了显著的变化。在将云冰水路径从≈5.5 g m-2 增加到≈9.3 g m-2 的其他模拟中，对船舶废气扰动的反应更加微弱，但发现根据云的微物理状态，废气扰动甚至可能导致轻微的辐射冷却效应。因此，航运活动对北极云特性的区域影响可能在很大程度上取决于船舶燃料类型、船舶是否使用湿式洗涤器以及决定主要云特性的环境热力学条件。
{"title":"Potential impacts of marine fuel regulations on Arctic clouds and radiative feedbacks","authors":"Luís Filipe Escusa dos Santos, Hannah C. Frostenberg, Alejandro Baró Pérez, Annica M. L. Ekman, Luisa Ickes, Erik S. Thomson","doi":"10.5194/egusphere-2024-1891","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1891","url":null,"abstract":"<strong>Abstract.</strong> Increased surface warming over the Arctic, triggered by increased greenhouse gas concentrations and feedback processes in the climate system, has been causing a steady decline in sea-ice extent and thickness. With the retreating sea-ice, shipping activity will likely increase in the future driven by economic activity and the potential for realizing time and fuel savings from transiting shorter trade routes. Moreover, over the last decade, the global shipping sector has been subject to regulatory changes, that affect the physicochemical properties of exhaust particles. International regulations aiming to reduce SO<sub>x</sub> and particulate matter (PM) emissions, mandate ships to burn fuels with reduced sulfur content or alternatively, use wet scrubbing as exhaust after-treatment when using fuels with sulfur contents exceeding regulatory limits. Compliance measures affect the physicochemical properties of exhaust particles and their cloud condensation nuclei (CCN) activity in different ways, with the potential to have both direct and indirect impacts on atmospheric processes such as the formation and lifetime of clouds. Given the relatively pristine Arctic environment, ship exhaust particle emissions could be a large perturbation to natural baseline Arctic aerosol concentrations. Low-level stratiform mixed-phase clouds cover large areas of the Arctic region and play an important role in the regional energy budget. Results from laboratory marine engine measurements, which investigated the impact of fuel sulfur content (FSC) reduction and wet scrubbing on exhaust particle properties, motivate the use of large eddy simulations to further investigate how such particles may influence the micro- and macrophysical properties of a stratiform mixed-phase cloud case observed during the Arctic Summer Cloud Ocean Study campaign. Simulated enhancements of ship exhaust particles predominantly affected the liquid-phase properties of the cloud and led to a decrease in liquid surface precipitation, increased cloud albedo and increased longwave surface warming. The magnitude of the impact strongly depended on ship exhaust particle concentration, hygroscopicity, and size where the effect of particle size dominated the impact of hygroscopicity. While low FSC exhaust particles were mostly observed to affect cloud properties at exhaust particle concentrations of 1000 cm<sup>-3</sup>, exhaust wet scrubbing already led to significant changes at concentrations of 100 cm<sup>-3</sup>. Additional simulations with cloud ice water path increased from ≈5.5 g m<sup>-2</sup> to ≈9.3 g m<sup>-2</sup>, show more muted responses to ship exhaust perturbations but revealed that exhaust perturbations may even lead to a slight radiative cooling effect depending on the microphysical state of the cloud. The regional impact of shipping activity on Arctic cloud properties may, therefore, strongly depend on ship fuel type, whether ships utilize wet scrubbers, and","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/acp-24-7331-2024
Johannes Mülmenstädt, Edward Gryspeerdt, Sudhakar Dipu, Johannes Quaas, Andrew S. Ackerman, Ann M. Fridlind, Florian Tornow, Susanne E. Bauer, Andrew Gettelman, Yi Ming, Youtong Zheng, Po-Lun Ma, Hailong Wang, Kai Zhang, Matthew W. Christensen, Adam C. Varble, L. Ruby Leung, Xiaohong Liu, David Neubauer, Daniel G. Partridge, Philip Stier, Toshihiko Takemura
Abstract. General circulation models' (GCMs) estimates of the liquid water path adjustment to anthropogenic aerosol emissions differ in sign from other lines of evidence. This reduces confidence in estimates of the effective radiative forcing of the climate by aerosol–cloud interactions (ERFaci). The discrepancy is thought to stem in part from GCMs' inability to represent the turbulence–microphysics interactions in cloud-top entrainment, a mechanism that leads to a reduction in liquid water in response to an anthropogenic increase in aerosols. In the real atmosphere, enhanced cloud-top entrainment is thought to be the dominant adjustment mechanism for liquid water path, weakening the overall ERFaci. We show that the latest generation of GCMs includes models that produce a negative correlation between the present-day cloud droplet number and liquid water path, a key piece of observational evidence supporting liquid water path reduction by anthropogenic aerosols and one that earlier-generation GCMs could not reproduce. However, even in GCMs with this negative correlation, the increase in anthropogenic aerosols from preindustrial to present-day values still leads to an increase in the simulated liquid water path due to the parameterized precipitation suppression mechanism. This adds to the evidence that correlations in the present-day climate are not necessarily causal. We investigate sources of confounding to explain the noncausal correlation between liquid water path and droplet number. These results are a reminder that assessments of climate parameters based on multiple lines of evidence must carefully consider the complementary strengths of different lines when the lines disagree.
{"title":"General circulation models simulate negative liquid water path–droplet number correlations, but anthropogenic aerosols still increase simulated liquid water path","authors":"Johannes Mülmenstädt, Edward Gryspeerdt, Sudhakar Dipu, Johannes Quaas, Andrew S. Ackerman, Ann M. Fridlind, Florian Tornow, Susanne E. Bauer, Andrew Gettelman, Yi Ming, Youtong Zheng, Po-Lun Ma, Hailong Wang, Kai Zhang, Matthew W. Christensen, Adam C. Varble, L. Ruby Leung, Xiaohong Liu, David Neubauer, Daniel G. Partridge, Philip Stier, Toshihiko Takemura","doi":"10.5194/acp-24-7331-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7331-2024","url":null,"abstract":"Abstract. General circulation models' (GCMs) estimates of the liquid water path adjustment to anthropogenic aerosol emissions differ in sign from other lines of evidence. This reduces confidence in estimates of the effective radiative forcing of the climate by aerosol–cloud interactions (ERFaci). The discrepancy is thought to stem in part from GCMs' inability to represent the turbulence–microphysics interactions in cloud-top entrainment, a mechanism that leads to a reduction in liquid water in response to an anthropogenic increase in aerosols. In the real atmosphere, enhanced cloud-top entrainment is thought to be the dominant adjustment mechanism for liquid water path, weakening the overall ERFaci. We show that the latest generation of GCMs includes models that produce a negative correlation between the present-day cloud droplet number and liquid water path, a key piece of observational evidence supporting liquid water path reduction by anthropogenic aerosols and one that earlier-generation GCMs could not reproduce. However, even in GCMs with this negative correlation, the increase in anthropogenic aerosols from preindustrial to present-day values still leads to an increase in the simulated liquid water path due to the parameterized precipitation suppression mechanism. This adds to the evidence that correlations in the present-day climate are not necessarily causal. We investigate sources of confounding to explain the noncausal correlation between liquid water path and droplet number. These results are a reminder that assessments of climate parameters based on multiple lines of evidence must carefully consider the complementary strengths of different lines when the lines disagree.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Stable nitrogen isotopic composition (δ15N) has proven to be a valuable tool for identifying sources of nitrates (NO3–) in PM2.5. However, the absence of a systematic study on the δ15N values of domestic NOx sources hinders accurate identification of NO3– sources in China. Here, we systematically determined and refined δ15N values for six categories of NOx sources in the local Tianjin area using an active sampling method. Moreover, the δ15N values of NO3– in PM2.5 were measured during pre-heating, mid-heating and late-heating periods, which are the most heavily polluted in Tianjin. Results shown that the representative nature and region-specific characteristics of isotopic fingerprints for six categories of NOx sources in Tianjin. The Bayesian isotope mixing (MixSIAR) model demonstrated that coal combustion, biomass burning, and vehicle exhaust collectively contributed more than 60 %, dominating the sources of NO3– during sampling periods in Tianjin. However, failure to consider the isotopic signatures of local NOx sources could result in an underestimation of the contribution from coal combustion. Additionally, the absence of industrial sources, an uncharacterized source in previous studies, may directly result in the contribution fraction of other sources being overestimated by the model more than 15 %. Notably, as the number of sources input to the model increased, the contribution of various NOx sources was becoming more stable, and the inter-influence between various sources significantly reduced. This study demonstrated that the refined isotopic fingerprint in a region-specific context could more effectively distinguish source of NO3–, thereby providing valuable insights for controlling NO3– pollution.
{"title":"Technical note: Refining δ15N isotopic fingerprints of local NOx for accurate source identification of nitrate in PM2.5","authors":"Hao Xiao, Qinkai Li, Shiyuan Ding, Wenjing Dai, Gaoyang Cui, Xiaodong Li","doi":"10.5194/egusphere-2024-1621","DOIUrl":"https://doi.org/10.5194/egusphere-2024-1621","url":null,"abstract":"<strong>Abstract.</strong> Stable nitrogen isotopic composition (δ<sup>15</sup>N) has proven to be a valuable tool for identifying sources of nitrates (NO<sub>3</sub><sup>–</sup>) in PM<sub>2.5</sub>. However, the absence of a systematic study on the δ<sup>15</sup>N values of domestic NOx sources hinders accurate identification of NO<sub>3</sub><sup>–</sup> sources in China. Here, we systematically determined and refined δ<sup>15</sup>N values for six categories of NOx sources in the local Tianjin area using an active sampling method. Moreover, the δ<sup>15</sup>N values of NO<sub>3</sub><sup>–</sup> in PM<sub>2.5</sub> were measured during pre-heating, mid-heating and late-heating periods, which are the most heavily polluted in Tianjin. Results shown that the representative nature and region-specific characteristics of isotopic fingerprints for six categories of NOx sources in Tianjin. The Bayesian isotope mixing (MixSIAR) model demonstrated that coal combustion, biomass burning, and vehicle exhaust collectively contributed more than 60 %, dominating the sources of NO<sub>3</sub><sup>–</sup> during sampling periods in Tianjin. However, failure to consider the isotopic signatures of local NOx sources could result in an underestimation of the contribution from coal combustion. Additionally, the absence of industrial sources, an uncharacterized source in previous studies, may directly result in the contribution fraction of other sources being overestimated by the model more than 15 %. Notably, as the number of sources input to the model increased, the contribution of various NOx sources was becoming more stable, and the inter-influence between various sources significantly reduced. This study demonstrated that the refined isotopic fingerprint in a region-specific context could more effectively distinguish source of NO<sub>3</sub><sup>–</sup>, thereby providing valuable insights for controlling NO<sub>3</sub><sup>–</sup> pollution.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141462408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27DOI: 10.5194/acp-24-7385-2024
Flora Maria Brocza, Peter Rafaj, Robert Sander, Fabian Wagner, Jenny Marie Jones
Abstract. Anthropogenic mercury (Hg) emissions to the atmosphere are a long-lived hazard to human and environmental health. The UN Minamata Convention on Mercury is seeking to lower anthropogenic mercury emissions through a mix of policies from banning certain Hg uses to reducing unintentional Hg release from different activities. In addition to independent Hg policy, strategies to mitigate greenhouse gases, particulate matter (PM) and SO2 may also lower Hg emissions as a co-benefit. This study uses the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) model to examine the effect of different clean air and climate policies on future global Hg emissions. The baseline scenario assumes current trends for energy use and Hg emissions as well as current legislation for clean air, mercury and climate policy. In addition, we explore the impact of the Minamata Convention, the co-benefits of climate and stringent air pollution policies, and maximum feasible reduction measures for Hg. Hg emission projections until 2050 show noticeable reductions in combustion sectors for all scenarios due to a decrease in global fossil fuel and traditional biomass use, leading to emission reductions of 33 % at baseline and up to 90 % when combining stringent climate controls and the most efficient Hg controls. Cement and non-ferrous metal emissions increase in all scenarios with current air pollution policy but could be reduced by up to 72 % and 46 %, respectively, in 2050 with stringent Hg-specific measures. Other emissions (including waste) are a significant source of uncertainty in this study, and their projections range between a 22 % increase and a 54 % decrease in 2050, depending on both climate and clean air policy. The largest absolute reduction potential for Hg abatement but also the largest uncertainties regarding absolute emissions lie in small-scale and artisanal gold production, where abatement measures could eliminate annual Hg emissions in the range of 601–1371 t (95 % confidence interval), although the uncertainties in the estimate are so high that they might eclipse reduction efforts in all other sectors. In total, 90 % of Hg emissions are covered by provisions of the Minamata Convention. Overall, the findings emphasize the necessity to implement targeted Hg control policies in addition to stringent climate, PM and SO2 policies to achieve significant reductions in Hg emissions.
{"title":"Global scenarios of anthropogenic mercury emissions","authors":"Flora Maria Brocza, Peter Rafaj, Robert Sander, Fabian Wagner, Jenny Marie Jones","doi":"10.5194/acp-24-7385-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7385-2024","url":null,"abstract":"Abstract. Anthropogenic mercury (Hg) emissions to the atmosphere are a long-lived hazard to human and environmental health. The UN Minamata Convention on Mercury is seeking to lower anthropogenic mercury emissions through a mix of policies from banning certain Hg uses to reducing unintentional Hg release from different activities. In addition to independent Hg policy, strategies to mitigate greenhouse gases, particulate matter (PM) and SO2 may also lower Hg emissions as a co-benefit. This study uses the Greenhouse Gas–Air Pollution Interactions and Synergies (GAINS) model to examine the effect of different clean air and climate policies on future global Hg emissions. The baseline scenario assumes current trends for energy use and Hg emissions as well as current legislation for clean air, mercury and climate policy. In addition, we explore the impact of the Minamata Convention, the co-benefits of climate and stringent air pollution policies, and maximum feasible reduction measures for Hg. Hg emission projections until 2050 show noticeable reductions in combustion sectors for all scenarios due to a decrease in global fossil fuel and traditional biomass use, leading to emission reductions of 33 % at baseline and up to 90 % when combining stringent climate controls and the most efficient Hg controls. Cement and non-ferrous metal emissions increase in all scenarios with current air pollution policy but could be reduced by up to 72 % and 46 %, respectively, in 2050 with stringent Hg-specific measures. Other emissions (including waste) are a significant source of uncertainty in this study, and their projections range between a 22 % increase and a 54 % decrease in 2050, depending on both climate and clean air policy. The largest absolute reduction potential for Hg abatement but also the largest uncertainties regarding absolute emissions lie in small-scale and artisanal gold production, where abatement measures could eliminate annual Hg emissions in the range of 601–1371 t (95 % confidence interval), although the uncertainties in the estimate are so high that they might eclipse reduction efforts in all other sectors. In total, 90 % of Hg emissions are covered by provisions of the Minamata Convention. Overall, the findings emphasize the necessity to implement targeted Hg control policies in addition to stringent climate, PM and SO2 policies to achieve significant reductions in Hg emissions.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Cold extremes have large impacts on human society. Understanding the physical processes dominating the changes in cold extremes is crucial for a reliable projection of future climate change. The observed cold extremes have decreased during the last several decades, and this trend will continue under future global warming. Here, we quantitatively identify the contributions of dynamic (changes in large-scale atmospheric circulation) and thermodynamic (rising temperatures resulting from global warming) effects to East Asian cold extremes in the past several decades and in a future warm climate by using two sets of large-ensemble simulations of climate models. We show that the dynamic component accounts for over 80 % of the cold-month (coldest 5 % boreal winter months) surface air temperature (SAT) anomaly over the past 5 decades. However, in a future warm climate, the thermodynamic change is the main contributor to the decreases in the intensity and occurrence probability of East Asian cold extremes, while the dynamic change is also contributive. The intensity of East Asian cold extremes will decrease by around 5 °C at the end of the 21st century, in which the thermodynamic (dynamic) change contributes approximately 75 % (25 %). The present-day (1986–2005) East Asian cold extremes will almost never occur after around 2035, and this will happen 10 years later due solely to thermodynamic change. The upward trend of a positive Arctic Oscillation-like sea level pressure pattern dominates the changes in the dynamic component. The finding provides a useful reference for policymakers in climate change adaptation activities.
{"title":"Future reduction of cold extremes over East Asia due to thermodynamic and dynamic warming","authors":"Donghuan Li, Tianjun Zhou, Youcun Qi, Liwei Zou, Chao Li, Wenxia Zhang, Xiaolong Chen","doi":"10.5194/acp-24-7347-2024","DOIUrl":"https://doi.org/10.5194/acp-24-7347-2024","url":null,"abstract":"Abstract. Cold extremes have large impacts on human society. Understanding the physical processes dominating the changes in cold extremes is crucial for a reliable projection of future climate change. The observed cold extremes have decreased during the last several decades, and this trend will continue under future global warming. Here, we quantitatively identify the contributions of dynamic (changes in large-scale atmospheric circulation) and thermodynamic (rising temperatures resulting from global warming) effects to East Asian cold extremes in the past several decades and in a future warm climate by using two sets of large-ensemble simulations of climate models. We show that the dynamic component accounts for over 80 % of the cold-month (coldest 5 % boreal winter months) surface air temperature (SAT) anomaly over the past 5 decades. However, in a future warm climate, the thermodynamic change is the main contributor to the decreases in the intensity and occurrence probability of East Asian cold extremes, while the dynamic change is also contributive. The intensity of East Asian cold extremes will decrease by around 5 °C at the end of the 21st century, in which the thermodynamic (dynamic) change contributes approximately 75 % (25 %). The present-day (1986–2005) East Asian cold extremes will almost never occur after around 2035, and this will happen 10 years later due solely to thermodynamic change. The upward trend of a positive Arctic Oscillation-like sea level pressure pattern dominates the changes in the dynamic component. The finding provides a useful reference for policymakers in climate change adaptation activities.","PeriodicalId":8611,"journal":{"name":"Atmospheric Chemistry and Physics","volume":null,"pages":null},"PeriodicalIF":6.3,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141461805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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