Journal of Climate最新文献

{"title":"Linearity of the Climate Response to Increasingly Strong Tropical Volcanic Eruptions in a Large Ensemble Framework","authors":"Claudia Timmreck, Dirk Olonscheck, Andrew P. Ballinger, Roberta D’Agostino, Shih-Wei Fang, Andrew P. Schurer, Gabriele C. Hegerl","doi":"10.1175/jcli-d-23-0408.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0408.1","url":null,"abstract":"Abstract Large explosive volcanic eruptions cause short-term climatic impacts on both regional and global scales. Their impact on tropical climate variability, in particular El Niño–Southern Oscillation (ENSO), is still uncertain, as is their combined and separate effect on tropical and global precipitation. Here, we investigate the relationship between large-scale temperature and precipitation and tropical volcanic eruption strength, using 100-member MPI-ESM ensembles for idealized equatorial symmetric Northern Hemisphere summer eruptions of different sulfur emission strengths. Our results show that for idealized tropical eruptions, global and hemispheric mean near-surface temperature and precipitation anomalies are negative and linearly scalable for sulfur emissions between 10 and 40 Tg S. We identify 20 Tg S emission as a threshold where the global ensemble-mean near-surface temperature and precipitation signals exceed the range of internal variability, even though some ensemble members emerge from variability for lower eruption strengths. Seasonal and ensemble mean patterns of near-surface temperature and precipitation anomalies are highly correlated across eruption strengths, in particular for larger emission strengths in the tropics, and strongly modulated by ENSO. There is a tendency to shift toward a warm ENSO phase for the first postvolcanic year as the emission strength increases. Volcanic cooling emerges on a hemisphere-wide scale, while the precipitation response is more localized, and emergence is mainly confined to the tropics and subtropics. Significance Statement The purpose of this study is to investigate at which strength the climate responses of volcanic forcing can be distinguished from the internal climate variability and whether the responses will linearly increase as the emission strengths become stronger. We ran 100-member MPI-ESM ensembles of idealized equatorial volcanic eruptions of different sulfur emission strengths and find that seasonal and ensemble mean patterns of near-surface temperature and precipitation anomalies are distinguishable and linearly scalable for sulfur emissions from 10 to 40 Tg S if their forcing patterns are similar. The identification of volcanic fingerprints is important for seasonal to decadal forecasts in the case of potential future eruptions and could help to prepare society for the regional climatic consequences of such an event.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"46 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140146404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of easterly QBO’s boreal winter teleconnections and surface impacts to SSWs","authors":"Dillon Elsbury, Amy Butler, Yannick Peings, Gudrun Magnusdottir","doi":"10.1175/jcli-d-23-0395.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0395.1","url":null,"abstract":"Abstract The Quasi-Biennial Oscillation (QBO) is thought to influence boreal winter surface conditions over Asia and around the North Atlantic. Confirming if these responses are robust is complicated by the QBO having multiple pathways to influence surface conditions as well as internal variability. The reanalysis record suggests that sudden stratospheric warmings (SSWs), breakdowns of the polar vortex that can elicit persistent surface impacts, are more frequent during easterly QBO (EQBO). Hence, this modulated frequency of SSWs may account for some of the EQBO surface responses. However, many climate models do not reproduce this QBO-SSW relationship, perhaps because it is noise or because the model QBOs are deficient. We circumvent these issues by using an ensemble of fixed boundary condition branched simulations in which a realistic EQBO is prescribed in control simulations previously devoid of a QBO, allowing us to isolate the transient atmospheric response to EQBO. Imposing EQBO accelerates the tropical upper tropospheric wind, shifts the subtropical jet poleward, and attenuates the polar vortex. Interestingly, the latter is not entirely dependent on the statistically significant increase in SSW frequency due to EQBO. Corroborating observations, EQBO is associated with warmer surface temperatures over Asia and negative North Atlantic Oscillation (NAO) conditions. We then subsample the branched/control simulations based on which EQBO members have SSWs. The negative NAO response is primarily associated with more frequent SSWs while the Asia warming develops irrespective of SSWs. These results have implications for wintertime predictability and clarify the pairing of particular QBO-teleconnections with certain surface impacts.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"68 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140146407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Responses of Lower Stratospheric water vapor to Regional Sea Surface Temperature Changes","authors":"Lingyu Zhou, Yan Xia, Fei Xie, Chen Zhou, Chuanfeng Zhao","doi":"10.1175/jcli-d-23-0600.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0600.1","url":null,"abstract":"Abstract The variability of stratospheric water vapor (SWV) plays a crucial role in stratospheric chemistry and the Earth's energy budget, strongly influenced by sea surface temperature (SST). In this study, we systematically investigate the response of low stratospheric water vapor (LSWV) to regional sea surface temperature changes using idealized SST patch experiments within a climate model. The results indicate that LSWV is most sensitive to tropical sea surface temperature, with the strongest response occurring in late autumn and early winter. Warming of the tropical Indian Ocean and western Pacific leads to stratospheric drying, while warming of the tropical Atlantic and eastern Pacific results in stratospheric moistening. The drying impact on LSWV due to warming in the western Pacific Ocean exceeds the wet effect in the Eastern Pacific Ocean by approximately 60%. The variations in tropical SST influence LSWV by modulating the temperature at the tropical tropopause layer especially over the Indo-Pacific Warm Pool through Matsuno-Gill responses. Furthermore, the response of LSWV to tropical SST changes exhibits nonnegligible nonlinearity, which indicates the importance of nonlinearity in determining the LSWV response to global surface warming.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"27 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140146402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Regional sea level response to external forcings from the 20th to the 21st century","authors":"Zhen Liu, Changlin Chen, Guihua Wang, Shouwei Li, Shouhua Liu","doi":"10.1175/jcli-d-23-0427.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0427.1","url":null,"abstract":"Abstract Using a range of Detection and Attribution Model Intercomparison Project (DAMIP) simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6), we study the response of dynamic sea level (DSL) to external anthropogenic climate forcing [greenhouse gases (GHGs), aerosols, and stratospheric ozone] with a focus on the differences over the 20th and 21st century. In the second half of the 20th century, the DSL nonuniformity in the Northern Hemisphere (NH) was relatively small due to a cancellation between the effects of increasing GHGs and aerosols. In contrast, the DSL signal in the Southern Hemisphere (SH) over this period was large because stratospheric ozone depletion reinforced the effects of increasing GHGs. In the 21st century, the DSL response has been intensified in the NH because the warming effects of diminishing aerosols have acted to reinforce the effects of increasing GHGs. Meanwhile the distribution of SH DSL has also become uneven although stratospheric ozone recovery has partially offset the effects of rising GHGs. Using a global ocean circulation model, we decompose the changes in 21st century DSL into distinct responses to surface forcings including sea surface temperature, salinity, and wind stress. Our results show that the dipole-like pattern of DSL in the North Pacific can be attributed largely to sea surface warming, while the dipole-like pattern in the North Atlantic is attributed to subpolar surface salinity freshening. The belted pattern of DSL changes in the Southern Ocean is induced by both surface warming and intensifying/poleward-shifting westerly winds.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"45 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140129952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observed Changes in Extreme Precipitation Associated with United States tropical cyclones","authors":"John Uehling, Carl J Schreck","doi":"10.1175/jcli-d-23-0327.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0327.1","url":null,"abstract":"Abstract Numerous recent tropical cyclones have caused extreme rainfall and flooding events in the CONUS. Climate change is contributing to heavier extreme rainfall around the world. Modeling studies have suggested that tropical cyclones may be particularly efficient engines for transferring the additional water vapor in the atmosphere into extreme rainfall. This paper develops a new indicator for climate change using the enhanced rainfall metric to evaluate how the frequency and/or intensity of extreme rainfall around tropical cyclones has changed. The enhanced rainfall metric relates the amount of rain from a storm over a given location to the 5-year return period rainfall in that location to determine the severity of the event. The annual area exposed to tropical cyclone-related 5-year rainfall events is increasing, which makes a compelling climate change indicator. Quantile regression illustrates that the distribution of tropical cyclone rainfall is also changing. For tropical storms, all quantiles are increasing. However, major hurricanes show large increases in their most extreme rainfall. This study does not attempt to make any detection claims (vs. natural variability) or attribution of the observed trends to anthropogenic forcing. However, the sensitivity of the results to natural variability in tropical cyclone frequency was somewhat constrained by comparing two decades from the previous active era (1951–1970) with two from the current era (2001–2020). This comparison also shows that both the mean and maximum rainfall associated with tropical cyclones is increasing over most areas of the eastern CONUS with the most significant increases from northern Alabama to the southern Appalachians.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"1 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140125000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in compound hot extremes over the mid-high latitudes of Asia and underlying mechanisms","authors":"Wenhao Jiang, Huopo Chen, Huijun Wang","doi":"10.1175/jcli-d-23-0502.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0502.1","url":null,"abstract":"Abstract This study investigates the spatiotemporal variations of summer frequency of day-nighttime compound extreme high-temperature events (FCEHE) in the mid-high latitudes of Asia (MHA) from 1979 to 2014. Results show that FCEHE has shown an upward trend with fluctuations, especially in Mongolia-Baikal. The descending anomaly caused by the anomalous high pressure over the Mongolia-Baikal results in reduced cloud cover, which increases solar radiation reaching the ground, favoring the higher FCEHE. This process is consistent during the daytime and nighttime periods, with relatively limited nighttime solar radiation, potentially compensated by the increased downward longwave radiation to sustain the extreme high temperatures. This benefit process is closely connected with two main factors: the increased sea ice in the Barents Sea during spring and the anomalously warm sea surface temperature (SST) in the Northwest Pacific during summer. The increased sea ice can affect the Eurasia teleconnection (EU), while the warm SST affects the Pacific-Japan/East Asia–Pacific pattern (PJ/EAP). Subsequently, these factors further modulate the circulation anomalies and then FCEHE.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"35 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140124998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep winter mixed layer anchored by the meandering Antarctic Circumpolar Current: Cross-basin variations","authors":"Zihan Song, Shang-Ping Xie, Lixiao Xu, Xiao-Tong Zheng, Xiaopei Lin, Yu-Fan Geng","doi":"10.1175/jcli-d-23-0174.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0174.1","url":null,"abstract":"Abstract A deep winter mixed layer forms north of the Antarctic Circumpolar Current (ACC) in the Indo-Pacific sectors, while the mixed layer depth (MLD) is shallow in the Atlantic. Using observations and a global atmospheric model, this study investigates the contribution of surface buoyancy flux and background stratification to inter-basin MLD variations. The surface heat flux is decomposed into broad-scale and frontal-scale variations. At the broad-scale, the meandering ACC path is accompanied by a zonal wavenumber-1 structure of sea surface temperature with a warmer Pacific than Atlantic; under the prevailing westerly winds, this temperature contrast results in larger surface heat loss facilitating deeper MLD in the Indo-Pacific sectors than the Atlantic. In the Indian sector, the intense ACC fronts strengthen surface heat loss compared to the Pacific. The surface freshwater flux pattern largely follows that of evaporation and reinforces the heat flux pattern, especially in the southeast Pacific. A diagnostic relationship is introduced to highlight the role of ACC’s sloping isopycnals in setting a weak sub-mixed-layer stratification north of ACC. This weak stratification varies in magnitude across basins. In the Atlantic and western Indian oceans where the ACC is at a low latitude (∼45°S), solar heating, intrusions of subtropical gyres and energetic mesoscale eddies together maintain relatively strong stratification. In the southeast Pacific, in comparison, the ACC reaches the southernmost latitude (56°S), far away from the subtropical front. This creates weaker stratification allowing deep mixed layers to form, aided by surface buoyancy loss.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"24 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140129772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Warm Arctic-Cold Eurasia (WACE) trend: inference from large ensemble model simulations","authors":"Ye-Jun Jun, Seok-Woo Son, Hera Kim, Hyo-Seok Park, Jin-Ho Yoon","doi":"10.1175/jcli-d-23-0491.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0491.1","url":null,"abstract":"Abstract Concurrent with global warming, the Eurasian continent has experienced frequent cold winters in recent decades. Although still debatable, such Eurasian winter cooling, which was particularly pronounced in the late 20th century, has been attributed to internal climate variability, the process of which remains elusive. By examining multi-model large ensemble simulations, this study explores the potential sources of internal climate variability responsible for the Eurasian winter cooling trend over 1987–2006. Model simulations show a large ensemble spread in the Eurasian winter temperature trend with an ensemble mean close to zero. A comparison of the ensemble members shows that a circulation pattern favorable for the Eurasian cooling is characterized by the anticyclonic and cyclonic enhancements of seal level pressure (SLP) trend in the sub-Arctic and Aleutian regions, respectively. This dipolar SLP trend is closely related to the deep Arctic warming, the change in midlatitude snow cover, and the enhancement of atmospheric convection over the tropical western Pacific. This result suggests that the Eurasian winter cooling is likely associated not only to the changes in mid- to high-latitude conditions but also to the changes in tropical convection. The possible mechanism of the tropically-induced Aleutian low deepening is also discussed.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"41 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140106513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationship between the Uncertainty of Empirical Orthogonal Function (EOF) Modes and Sampling Sizes in Climate Models","authors":"Tong Shen, Riyu Lu","doi":"10.1175/jcli-d-23-0165.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0165.1","url":null,"abstract":"Abstract This study investigates the relationship between the uncertainty of empirical orthogonal function (EOF) modes and sampling size in climate models, using simulated results of preindustrial control (piControl) experiments in phase 6 of the Coupled Model Intercomparison Project (CMIP6), and taking the North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation (ENSO) as examples. The results indicate that this relationship can be quantified by a concise fitting function [i.e., y = a/(x − b)]. Here, y is the 5%–95% confidence interval of congruence coefficient, x is the sampling size, and a and b are two parameters depending on models or observations. As compared with b, which modulates the sampling size in the fitting function, the parameter a scales the sampling size and thus plays a much more important role. Further analysis indicates that the parameter a, or the uncertainty of EOF1 mode, decreases dramatically with the increase of the difference between variance fractions of EOF1 and EOF2 modes, approximately in the form of a power function. The minimum sampling size to ensure a reliable EOF mode can also be estimated by the fitting function and shows a great diversity among models both for the NAO and ENSO. The diversity suggests the importance of estimating the minimum sampling size before model evaluations on climate variability modes and projections on the future change in modes, particularly when the EOF2 mode explains the variance close to EOF1 mode. Significance Statement Empirical orthogonal function (EOF) analysis, principal component analysis, or eigenvector analysis has been widely used in various research fields. However, it remains as an open question as to how large the sampling size is required to be to obtain reliable modes through the EOF method. In this study, we investigate the relationship between the uncertainty of EOF results and sampling size in current climate models, using adequately long simulated data, and we find that this relationship can be depicted by the fitting function y = a/(x − b). Here, y represents the uncertainty, x is the sampling size, and a and b are parameters. The parameter a is closely related to the difference between variance fractions of first and second EOF modes and plays a more important role in the fitting function. The minimum sampling sizes that are required to obtain reliable EOF modes can also be estimated by the fitting function and vary greatly from model to model. The results provide a basis for judging the reliability of EOF modes, particularly when the first and second EOF modes explain similar variance fractions.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"34 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The relative importance of Antarctic sea-ice loss within the response to greenhouse warming","authors":"Stephanie Hay, Paul J. Kushner","doi":"10.1175/jcli-d-23-0524.1","DOIUrl":"https://doi.org/10.1175/jcli-d-23-0524.1","url":null,"abstract":"Abstract The response to Antarctic sea-ice loss within a coupled modelling framework is examined in comparison to the response to Arctic sea-ice loss and within the context of general greenhouse warming. Sea-ice loss responses are found to be linear (particularly in response to Antarctic or global sea-ice loss) with respect to the degree of imposed perturbation and additive when perturbations are applied in hemispheres separately and concurrently. Globally, and in the tropical Pacific in particular, Antarctic sea-ice loss plays a relatively larger role than Arctic sea-ice loss in both the atmosphere and the ocean, within the parameters of our experiments. The pattern of response to Antarctic sea-ice loss is also found to more closely resemble that of greenhouse warming, again particularly in the tropics. An extension to multi-parameter pattern scaling is developed to include a scaling factor for Antarctic change in addition to those for tropical warming and Arctic sea-ice loss. The decomposition is applied to the modelled response to Antarctic sea-ice loss to break it down into component partial responses that scale with Antarctic, tropical, and Arctic changes. This reveals the aspects of the response that are directly related to Antarctic change, such as an equatorward intensification of tropical precipitation in the Northern Hemisphere, and those that are modified via the induced changes in the tropics and Arctic, such as Northern Hemisphere temperature change. With this, we hope to gain a deeper understanding of the role of each of these changes for the development of physical mechanisms of the response.","PeriodicalId":15472,"journal":{"name":"Journal of Climate","volume":"39 1","pages":""},"PeriodicalIF":4.9,"publicationDate":"2024-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140076451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}