Weather and Climate Dynamics最新文献

{"title":"Improved extended-range prediction of persistent stratospheric perturbations using machine learning","authors":"Raphaël de Fondeville, Zheng Wu, E. Székely, G. Obozinski, D. Domeisen","doi":"10.5194/wcd-4-287-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-287-2023","url":null,"abstract":"Abstract. On average every 2 years, the stratospheric polar vortex exhibits extreme perturbations known as sudden stratospheric warmings (SSWs).\u0000The impact of these events is not limited to the stratosphere: but they can also influence the weather at the surface of the Earth for up to 3 months after their occurrence. This downward effect is observed in particular for SSW events with extended recovery timescales.\u0000This long-lasting stratospheric impact on surface weather can be leveraged to significantly improve the performance of weather forecasts on timescales of weeks to months.\u0000In this paper, we present a fully data-driven procedure to improve the performance of long-range forecasts of the stratosphere around SSW events with an extended recovery.\u0000We first use unsupervised machine learning algorithms to capture the spatio-temporal dynamics of SSWs and to create a continuous scale index measuring both the frequency and the strength of persistent stratospheric perturbations.\u0000We then uncover three-dimensional spatial patterns maximizing the correlation with positive index values, allowing us to assess when and where statistically significant early signals of SSW occurrence can be found.\u0000Finally, we propose two machine learning (ML) forecasting models as competitors for the state-of-the-art sub-seasonal European Centre for Medium-Range Weather Forecasts (ECMWF) numerical prediction model S2S (sub-seasonal to seasonal): while the numerical model performs better for lead times of up to 25 d, the ML models offer better predictive performance for greater lead times.\u0000We leverage our best-performing ML forecasting model to successfully post-process numerical ensemble forecasts and increase their performance by up to 20 %.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131868889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of links between dynamical scenarios and particularly high impact of Aeolus on numerical weather prediction (NWP) forecasts","authors":"Anne Martin, M. Weissmann, A. Cress","doi":"10.5194/wcd-4-249-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-249-2023","url":null,"abstract":"Abstract. Global wind profiles from the Aeolus satellite mission provide an important source of wind information for numerical weather prediction (NWP). Data assimilation experiments show large mean changes in the analysis and a significant reduction in forecast errors. At Deutscher Wetterdienst (DWD), a 3-month observing system experiment (OSE), from July 2020 to October 2020, was performed to evaluate the impact of the Aeolus horizontal line-of-sight (HLOS) wind observations in the operational data assimilation system of the ICOsahedral Nonhydrostatic (ICON) global model. To better understand the underlying dynamics leading to the overall beneficial impact, specific time periods and regions with a particularly high impact of Aeolus are investigated. In this study, we illustrate three examples of atmospheric phenomena that constitute dynamical scenarios for significant forecast error reduction through the assimilation of Aeolus: the phase shift of large-scale tropical circulation systems, namely the Quasi-Biennial Oscillation (QBO) and the El Niño–Southern Oscillation (ENSO), and the interaction of tropical cyclones undergoing extratropical transition (ET) with the midlatitude waveguide.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128302094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects on early monsoon rainfall in West Africa due to recent deforestation in a convection-permitting ensemble","authors":"J. Crook, C. Klein, S. Folwell, C. Taylor, D. Parker, A. Bamba, K. Kouadio","doi":"10.5194/wcd-4-229-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-229-2023","url":null,"abstract":"Abstract. Tropical deforestation can have a significant effect on climate, but research attention has been directed mostly towards Amazonian deforestation. The southern part of West Africa (a region dependent on rain-fed agriculture and vulnerable to droughts and flooding) has seen significant deforestation since the 1950s. Many previous tropical deforestation studies have used idealized and exaggerated deforestation scenarios and parameterized convection models. In this study we estimate for the first time realistic historical deforestation from the Land-Use Harmonization dataset in West Africa and simulate the impacts in a 5 d ensemble forecast in June using a convection-permitting regional climate model. We find that sensible heat flux increases at the expense of latent heat flux in most deforested regions, and rainfall increases by an average of 8.4 % over deforested pixels from 18:00–06:00 UTC, whereas changes are much less pronounced during the day. Over large areas of deforestation approx. 300 km inland (e.g. west Guinea) the roughness-length and thermally enhanced convergence during the afternoon and evening occurs over the deforested areas resulting in increases in rainfall with little impact from reduced daytime humidity. In areas of coastal deforestation (e.g. Côte d'Ivoire), increased winds drive the sea breeze convection inland, resulting in evening rainfall reductions over the deforested area but increases further inland, in line with observations. We suggest our results would not be replicated in parameterized convection models, which are known to struggle with capturing peak convective activity in the late afternoon and long-lived nocturnal rainfall and with reproducing observed surface–rainfall feedbacks.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132417377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using large ensembles to quantify the impact of sudden stratospheric warmings and their precursors on the North Atlantic Oscillation","authors":"P. Bett, Adam A. Scaife, S. Hardiman, H. Thornton, Xiao‐Hua Shen, Lin Wang, Bo Pang","doi":"10.5194/wcd-4-213-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-213-2023","url":null,"abstract":"Abstract. Sudden-stratospheric-warming (SSW) events are often followed by significant weather and climate impacts at the surface. By affecting the North Atlantic Oscillation (NAO), SSWs can lead to periods of extreme cold in parts of Europe and North America. Previous studies have used observations and free-running climate models to try to identify features of the atmosphere prior to an SSW that can determine the subsequent impact at the surface. However, the limited observational record makes it difficult to accurately quantify these relationships. Here, we instead use a large\u0000ensemble of seasonal hindcasts. We first test whether the hindcasts reproduce the observed characteristics of SSWs and their surface signature. We find that the simulations are statistically indistinguishable from the observations, in terms of the overall risk of an SSW per winter (56 %), the frequency of SSWs with negative NAO responses (65 %), the magnitude of the NAO responses, and the frequency of wavenumber-2-dominated SSWs\u0000(26 %). We also assess the relationships between prior conditions and the NAO response in the 30 d following an SSW. We find that there\u0000is little information in the precursor state to guide differences in the subsequent NAO behaviour between one SSW and another, reflecting the\u0000substantial natural variability between SSW events. The strongest relationships with the NAO response are from pre-SSW sea level pressure anomalies over the polar cap and from zonal-wind anomalies in the lower stratosphere, both exhibiting correlations of around 0.3. The pre-SSW NAO has little bearing on its post-SSW state. The strength of the pre-SSW zonal-wind anomalies at 10 hPa is also not significantly correlated with the NAO response. Finally, we find that the mean NAO response in the first 10 d following wave-2-dominated SSWs is much more strongly negative than in wave-1 cases. However, the subsequent response in days 11–30 is very similar regardless of the dominant wavenumber. In all cases, the composite mean responses are the result of very broad distributions from individual SSW events, necessitating a probabilistic analysis using large ensembles.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115829260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vortex streets to the lee of Madeira in a kilometre-resolution regional climate model","authors":"Qinggang Gao, Christian Zeman, J. Vergara-Temprado, D. Lima, P. Molnar, C. Schär","doi":"10.5194/wcd-4-189-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-189-2023","url":null,"abstract":"Abstract. Atmospheric vortex streets are a widely studied dynamical effect of isolated mountainous islands. Observational evidence comes from case studies and satellite imagery, but the climatology and annual cycle of vortex shedding are often poorly understood. Using the non-hydrostatic limited-area COSMO model driven by the ERA-Interim reanalysis, we conducted a 10-year-long simulation over a mesoscale domain covering the Madeira and Canary archipelagos at high spatial (grid spacing of 1 km) and temporal resolutions. Basic properties of vortex streets were analysed and validated through a 6 d long case study in the lee of Madeira Island. The simulation compares well with satellite and aerial observations and with existing literature on idealised simulations. Our results show a strong dependency of vortex shedding on local and synoptic-flow conditions, which are to a large extent governed by the location, shape and strength of the Azores high. As part of the case study, we developed a vortex identification algorithm. The algorithm is based on a set of criteria and enabled us to develop a climatology of vortex shedding from Madeira Island for the 10-year simulation period. The analysis shows a pronounced annual cycle with an increasing vortex-shedding rate from April to August and a sudden decrease in September. This cycle is consistent with mesoscale wind conditions and local inversion height patterns.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131003540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anomalous subtropical zonal winds drive decreases in southern Australian frontal rain","authors":"A. Pepler, I. Rudeva","doi":"10.5194/wcd-4-175-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-175-2023","url":null,"abstract":"Abstract. Cold fronts make a significant contribution to cool season rainfall in the extratropics and subtropics. In many regions of the\u0000Southern Hemisphere the amount of frontal rainfall has declined in recent\u0000decades, but there has been no change in frontal frequency. We show that for\u0000southeast Australia this contradiction cannot be explained by changes in\u0000frontal intensity or moisture at the latitudes of interest. Rather,\u0000declining frontal rainfall in southeast Australia is associated with\u0000weakening of the subtropical westerlies in the mid-troposphere, which is\u0000part of a hemispheric pattern of wind anomalies that modify the\u0000extratropical zonal wave 3. Fronts that generate rainfall are associated\u0000with strong westerlies that penetrate well into the subtropics, and the\u0000observed decrease in frontal rainfall in southern Australia can be linked to\u0000a decrease in the frequency of fronts with strong westerlies at\u000025∘ S.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"229 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116438667","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Origin of low-tropospheric potential vorticity in Mediterranean cyclones","authors":"Alexander Scherrmann, H. Wernli, E. Flaounas","doi":"10.5194/wcd-4-157-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-157-2023","url":null,"abstract":"Abstract. Mediterranean cyclones are extratropical cyclones, typically of smaller size and weaker intensity than other cyclones that develop over the main open ocean storm tracks. Nevertheless, Mediterranean cyclones can attain high intensities, even comparable to the ones of tropical cyclones, and thus cause large socioeconomic impacts in the densely populated coasts of the region. After cyclogenesis takes place, a large variety of processes are involved in the cyclone’s development, contributing with positive and negative potential vorticity (PV) changes to the lower-tropospheric PV anomalies in the cyclone center. Although the diabatic processes that produce these PV anomalies in Mediterranean cyclones are known, it is still an open question whether they occur locally within the cyclone itself or remotely in the environment (e.g., near high orography) with a subsequent transport of high-PV air into the cyclone center. This study introduces a Lagrangian method to determine the origin of the lower-tropospheric PV anomaly, which is applied climatologically to ERA5 reanalysis and to 12 monthly simulations, performed with the integrated forecasting system (IFS) model. We define and quantify so-called “cyclonic” and “environmental” PV and find that the main part of the lower-tropospheric PV anomaly (60 %) is produced within the cyclone, shortly prior (−12 h) to the cyclones' mature stage. Nevertheless, in 19.5 % of the cyclones the environmental PV production near the mountains surrounding the Mediterranean Basin plays a significant role in forming the low-tropospheric PV anomaly and therefore in determining the intensity of these cyclones. The analysis of PV tendencies from the IFS simulations reveals that the major PV production inside the cyclone is typically due to convection and microphysics, whereas convection and turbulent momentum tendencies cause most of the positive PV changes in the environment.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114282159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Warm conveyor belts in present-day and future climate simulations – Part 1: Climatology and impacts","authors":"H. Joos, M. Sprenger, Hanin Binder, U. Beyerle, H. Wernli","doi":"10.5194/wcd-4-133-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-133-2023","url":null,"abstract":"Abstract. This study investigates how warm conveyor belts (WCBs) will change in a future climate. WCBs are strongly ascending airstreams in extratropical cyclones that are responsible for most of their precipitation. In conjunction with the cloud formation, latent heat is released, which has an impact on the potential vorticity distribution and therefore on the atmospheric circulation in the middle and upper troposphere. Because of these and other impacts of WCBs, it is of great importance to investigate changes in their frequencies, regions of occurrence, and physical characteristics in a warmer climate. To this aim, future climate simulations (Representative Concentration Pathway 8.5 – RCP8.5 – scenario; 2091–2100) are performed with the Community Earth System Model version 1 (CESM1) and compared to present-day climate (1991–1999). Trajectories are calculated based on 6-hourly 3D wind fields, and WCBs are identified as trajectories that ascend at least 600 hPa in 2 d. WCBs are represented reasonably well in terms of location and occurrence frequency compared to WCBs in the ERA-Interim reanalyses. In a future climate, WCB inflow regions in the North Pacific are systematically shifted northward in winter, which is in agreement with the northward shift of the storm track in this region. In the North Atlantic, increased frequencies are discernible in the southwest and there is a decrease to the south of Iceland. Finally, in the Southern Hemisphere, WCB frequencies increase in the South Atlantic in both seasons and to the east of South Africa and the Indian Ocean in June–July–August (JJA). These changes are partly consistent with corresponding changes in the occurrence frequencies of extratropical cyclones, i.e. the driving weather systems of WCBs. Changes are also found in the WCB characteristics, which have implications for WCB impacts in a future climate. The increase in inflow moisture in the different regions and seasons – ∼23 %–33 % (∼14 %–20 %) in winter (summer) – leads to (i) an increase in WCB-related precipitation – ∼13 %–23 % (∼7 %–28 %) in winter (summer) – especially in the upper percentiles and thus a possible increase in extreme precipitation related to WCBs, (ii) a strong increase in diabatic heating – ∼20 %–27 % (∼17 %–33 %) in winter (summer) – in the mid-troposphere, and (iii) a higher outflow level – ∼10 K (∼10–16 K) in winter (summer) – which favours WCBs more strongly interacting with the upper-level Rossby waveguide. In summary, by investigating a distinct weather system, the WCB, and how it changes in its occurrence frequency and characteristics in a future climate, this study provides new insights into the dynamics and impacts of climate change in the extratropical storm track regions.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127273646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cloud-radiative impact on the dynamics and predictability of an idealized extratropical cyclone","authors":"Behrooz Keshtgar, A. Voigt, C. Hoose, M. Riemer, B. Mayer","doi":"10.5194/wcd-4-115-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-115-2023","url":null,"abstract":"Abstract. Extratropical cyclones drive midlatitude weather, including extreme events, and determine midlatitude climate. Their dynamics and predictability are strongly shaped by cloud diabatic processes. While the cloud impact due to latent heating is much studied, little is known about the impact of cloud radiative heating (CRH) on the dynamics and predictability of extratropical cyclones. Here, we address this question by means of baroclinic life cycle simulations performed at a convection-permitting resolution of 2.5 km with the ICON model. The simulations use a newly implemented channel setup with periodic boundary conditions in the zonal direction. Moreover, the simulations apply a new modeling technique for which only CRH interacts with the cyclone, which circumvents changes in the mean state due to clear-sky radiative cooling that has complicated the interpretation of previous work. We find that CRH increases the kinetic energy of the cyclone system. The impact is most prominent at upper levels. To understand the CRH impact on the upper-tropospheric circulation, we diagnose the evolution of differences in potential vorticity between a simulation with and without CRH, and we quantify through which processes these differences grow over the course of the cyclone's life cycle. According to this diagnostic, CRH affects the cyclone mostly via the intensification of latent heating from cloud microphysical processes. Near the tropopause, direct diabatic modification of potential vorticity by intensified latent heat release precedes further changes in the tropopause by the upper-tropospheric divergent flow, which represents an indirect impact of latent heat release. Subsequently, differences in the tropopause structure amplify with the rotational flow during the highly nonlinear stage of the baroclinic wave. Our results show that although CRH is comparably small in magnitude, it can affect extratropical cyclones by changing cloud microphysical heating and subsequently the large-scale flow. The CRH impact follows a previously identified mechanism of multi-stage upscale error growth. At the same time, simulations in which CRH is disabled after certain days show that the CRH impact operates throughout the entire intensification phase of the cyclone. This means that CRH does not merely provide an arbitrary initial perturbation to the cyclone, from which differences grow in a generic way. Instead, our results suggest that uncertainties associated with the representation of CRH in numerical models have a more systematic impact and may more fundamentally influence model predictions of extratropical cyclones.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129379187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconciling conflicting evidence for the cause of the observed early 21st century Eurasian cooling","authors":"S. Outten, Camille Li, M. King, L. Suo, P. Y. F. Siew, H. Cheung, Richard Davy, E. Dunn‐Sigouin, T. Furevik, Shengping He, E. Madonna, S. Sobolowski, T. Spengler, T. Woollings","doi":"10.5194/wcd-4-95-2023","DOIUrl":"https://doi.org/10.5194/wcd-4-95-2023","url":null,"abstract":"Abstract. It is now well established that the Arctic is warming at a faster rate than the global average. This warming, which has been accompanied by a dramatic decline in sea ice, has been linked to cooling over the Eurasian subcontinent over recent decades, most dramatically during the period 1998–2012. This is a counter-intuitive impact under global warming given that land regions should warm more than ocean (and the global average). Some studies have proposed a causal teleconnection from Arctic sea-ice retreat to Eurasian wintertime cooling; other studies argue that Eurasian cooling is mainly driven by internal variability. Overall, there is an impression of strong disagreement between those holding the “ice-driven” versus “internal variability” viewpoints. Here, we offer an alternative framing showing that the sea ice and internal variability views can be compatible. Key to this is viewing Eurasian cooling through the lens of dynamics (linked primarily to internal variability with some potential contribution from sea ice; cools Eurasia) and thermodynamics (linked to sea-ice retreat; warms Eurasia). This approach, combined with recognition that there is uncertainty in the hypothesized mechanisms themselves, allows both viewpoints (and others) to co-exist and contribute to our understanding of Eurasian cooling. A simple autoregressive model shows that Eurasian cooling of this magnitude is consistent with internal variability, with some periods exhibiting stronger cooling than others, either by chance or by forced changes. Rather than posit a “yes-or-no” causal relationship between sea ice and Eurasian cooling, a more constructive way forward is to consider whether the cooling trend was more likely given the observed sea-ice loss, as well as other sources of low-frequency variability. Taken in this way both sea ice and internal variability are factors that affect the likelihood of strong regional cooling in the presence of ongoing global warming.\u0000","PeriodicalId":383272,"journal":{"name":"Weather and Climate Dynamics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123796791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}