Atmospheric Heating Research Articles

Improved Representations of Longwave Surface Emissivity to Reduce Surface and Atmospheric Heating Biases in Earth System Models

AbstractMany Earth system models (ESMs) approximate surface emissivity as a broadband constant. This approximation reduces the computational burden, yet omits the spectral structure of emissivity and atmospheric absorption. Neglecting spectral variation in surface emission introduces biases in longwave (LW) atmospheric fluxes and heating. Biases are strongest over surfaces with strongly varying emissivity and minimal atmospheric opacity. We examine these biases over water, ice, and snow surfaces. We partition spectral emissivity into the 16 spectral bands utilized by a single‐column atmospheric radiative transfer model (RRTMG_LW) commonly used in ESMs. We quantify flux and heating biases introduced by broadband assumptions relative to the spectrally resolved case for standard atmospheric profiles over each surface type. Current assumptions tend to overestimate upwelling surface fluxes; for example, the greybody assumption overestimates flux by 1.6 W/m2 (0.52%) at the bottom of a mid‐latitude winter atmosphere over ice, and by 2.33 (1.0%) at the top of atmosphere. The blackbody assumption tends to artificially cool Earth's surface, stabilizing the lower troposphere. Interestingly, the optimal broadband emissivity can deviate from the Planck‐weighted mean by up to 3% depending on surface type and atmospheric profile. We investigate bias sensitivity to surface temperature, cloud water path, and atmospheric water vapor. Bias is most sensitive to water vapor content, and least sensitive to cloud water path. Lastly, we show that a modified greybody method with updated broadband values can reduce total surface flux bias up to 1.69 , comparable to a five‐band approach and at a fraction of the computational cost.

Spectroscopically Resolved Partial Phase Curve of the Rapid Heating and Cooling of the Highly Eccentric Hot Jupiter HAT-P-2b with WFC3

Abstract The extreme environments of transiting close-in exoplanets in highly eccentric orbits are ideal for testing exoclimate physics. Spectroscopically resolved phase curves not only allow for the characterization of their thermal response to irradiation changes but also unveil phase-dependent atmospheric chemistry and dynamics. We observed a partial phase curve of the highly eccentric close-in giant planet HAT-P-2b (e = 0.51, M = 9M Jup) with the Wide Field Camera 3 aboard the Hubble Space Telescope. Using these data, we updated the planet's orbital parameters and radius and retrieved high-frequency pulsations consistent with the planet-induced pulsations reported in Spitzer data. We found that the peak in planetary flux occurred at 6.7 ± 0.6 hr after periastron, with heating and cooling timescales of 9 . 0 − 2.1 + 3.5 hr and 3 . 6 − 0.6 + 0.7 hr, respectively. We compare the light curve to various 1D and 3D forward models, varying the planet's chemical composition. The strong contrast in flux increase and decrease timescales before and after periapse indicates an opacity term that emerges during the planet's heating phase, potentially due to more H− than expected from chemical equilibrium models. The phase-resolved spectra are largely featureless, which we interpret as indicative of an inhomogeneous dayside. However, we identified an anomalously high flux in the spectroscopic bin coinciding with the hydrogen Paβ line, and that is likely connected to the planet's orbit. We interpret this as due to shock heating of the upper atmosphere given the short timescale involved, or evidence for other star−planet interactions.

Drought in a warmer, CO2-rich climate restricts grassland water use and soil water mixing.

Soil water sustains terrestrial life, yet its fate is uncertain under a changing climate. We conducted a deuterium labeling experiment to determine whether elevated atmospheric carbon dioxide (CO2), warming, and drought impact soil water storage and transport in a temperate grassland. Elevated CO2 created a wetter rootzone compared with ambient conditions, whereas warming decreased soil moisture. Soil water remained well mixed in all global change treatments except for summer drought combined with warming and elevated CO2. These combined treatments caused the grassland to conserve water and restricted soil water flow to large, rapidly draining pores without mixing with small, slowly draining pores. Our results suggest that drought in a warmer, more CO2-rich climate can severely alter grassland ecohydrology by constraining postdrought soil water flow and grassland water use.

Polar mesospheric ozone loss initiates downward coupling of solar signal in the Northern Hemisphere

Solar driven energetic particle precipitation (EPP) is an important factor in polar atmospheric ozone balance and has been linked to ground-level regional climate variability. However, the linking mechanism has remained ambiguous. The observed and simulated ground-level changes start well before the processes from the main candidate, the so-called EPP-indirect effect, would start. Here we show that initial reduction of polar mesospheric ozone and the resulting change in atmospheric heating rapidly couples to dynamics, transferring the signal downwards, shifting the tropospheric jet polewards. This pathway is not constrained to the polar vortex. Rather, a subtropical route initiated by a changing wind shear plays a key role. Our results show that the signal propagates downwards in timescales consistent with observed tropospheric level climatic changes linked to EPP. This pathway, from mesospheric ozone to regional climate, is independent of the EPP-indirect effect, and solves the long-standing mechanism problem for EPP effects on climate.

Standardized Methods to Assess the Impacts of Thermal Stress on Coral Reef Marine Life.

The Earth's oceans have absorbed more than 90% of the excess, climate change-induced atmospheric heat. The resulting rise in oceanic temperatures affects all species and can lead to the collapse of marine ecosystems, including coral reefs. Here, we review the range of methods used to measure thermal stress impacts on reef-building corals, highlighting current standardization practices and necessary refinements to fast-track discoveries and improve interstudy comparisons. We also present technological developments that will undoubtedly enhance our ability to record and analyze standardized data. Although we use corals as an example, the methods described are widely employed in marine sciences, and our recommendations therefore apply to all species and ecosystems. Enhancing collaborative data collection efforts, implementing field-wide standardized protocols, and ensuring data availability through dedicated, openly accessible databases will enable large-scale analysis and monitoring of ecosystem changes, improving our predictive capacities and informing active intervention to mitigate climate change effects on marine life.

Pervasive glacier retreats across Svalbard from 1985 to 2023.

A major uncertainty in predicting the behaviour of marine-terminating glaciers is ice dynamics driven by non-linear calving front retreat, which is poorly understood and modelled. Using 124919 calving front positions for 149 marine-terminating glaciers in Svalbard from 1985 to 2023, generated with deep learning, we identify pervasive calving front retreats for non-surging glaciers over the past 38 years. We observe widespread seasonal cycles in calving front position for over half of the glaciers. At the seasonal timescale, peak retreat rates exhibit a several-month phaselag, with changes on the west coast occurring before those on the east coast, coincident with regional ocean warming. This spatial variability in seasonal patterns is linked to different timings of warm ocean water inflow from the West Spitsbergen Current, demonstrating the dominant role of ice-ocean interaction in seasonal front changes. The interannual variability of calving front retreat shows a strong sensitivity to both atmospheric and oceanic warming, with immediate responses to large air and ocean temperature anomalies in 2016 and 2019, likely driven by atmospheric blocking that can influence extreme temperature variability. With more frequent blocking occurring and continued regional warming, future calving front retreats will likely intensify, leading to more significant glacier mass loss.

Ecophysiological responses to heat waves in the marine intertidal zone.

One notable consequence of climate change is an increase in the frequency, scale and severity of heat waves. Heat waves in terrestrial habitats (atmospheric heat waves, AHW) and marine habitats (marine heat waves, MHW) have received considerable attention as environmental forces that impact organisms, populations and whole ecosystems. Only one ecosystem, the intertidal zone, experiences both MHWs and AHWs. In this Review, we outline the range of responses that intertidal zone organisms exhibit in response to heat waves. We begin by examining the drivers of thermal maxima in intertidal zone ecosystems. We develop a simple model of intertidal zone daily maximum temperatures based on publicly available tide and solar radiation models, and compare it with logged, under-rock temperature data at an intertidal site. We then summarize experimental and ecological studies of how intertidal zone ecosystems and organisms respond to heat waves across dimensions of biotic response. Additional attention is paid to the impacts of extreme heat on cellular physiology, including oxidative stress responses to thermally induced mitochondrial overdrive and dysfunction. We examine the energetic consequences of these mechanisms and how they shift organismal traits, including growth, reproduction and immune function. We conclude by considering important future directions for improving studies of the impacts of heat waves on intertidal zone organisms.

Ohmic heating in the upper atmosphere of hot exoplanets. The influence of a time-varying magnetic field

Exoplanets on close-in orbits are subject to intense X-ray and ultraviolet (XUV) irradiation from their star. Their atmosphere heats up, sometimes to the point where it will thermally escape from the gravitational potential of the planet. Nonetheless, XUV is not the only source of heating in such atmospheres. Indeed, close-in exoplanets are embedded in a medium (the stellar wind) with strong magnetic fields that can significantly vary along the orbit. Variations in this magnetic field can induce currents in the upper atmosphere, which dissipate and locally heat it up through Ohmic heating. The aim of this work is to quantify Ohmic heating in the upper atmosphere of hot exoplanets, due to an external time-varying magnetic field, and to compare it to the XUV heating. Ohmic heating depends strongly on the conductivity properties of the upper atmosphere. We developed a 1D formalism to assess the level and the localization of Ohmic heating depending on the conductivity profile. The formalism is applied to the specific cases of Trappist-1 b and π Men c. Ohmic heating can reach values up to 10^-3 erg s^-1 cm^-3 in the upper atmospheres of hot exoplanets. It is expected to be stronger the closer the planet and the lower its central star mass, as these conditions maximize the strength of the ambient magnetic field around the planet. The location of maximal heating depends on the conductivity profile (but does not necessarily occurs at the peak of conductivity) and, in particular, on the existence and strength of a steady planetary field. Such extra heating can play a role in the thermal budget of the escaping atmosphere when the planetary atmospheric magnetic fields is between 0.01 G and 1G. We confirm that Ohmic heating can play an important role in setting the thermal budget of the upper atmosphere of hot exoplanets and can even surpass the XUV heating in the most favorable cases. When it is strong, a corollary is that the upper atmosphere screens efficiently time-varying external magnetic fields, preventing them from penetrating deeper in the atmosphere or even within the planet itself. We find that both Trappist-1b and π Men c are likely being subjected to intense Ohmic heating.

Development and Evaluation of a New Correlated K‐Distribution Scheme for BCC_RAD Radiative Transfer Model

AbstractWith the significant increase in the abundance of greenhouse gases in the atmosphere over recent decades, more of the weak gaseous absorption bands are required to be incorporated in the gas optics model to improve the computational accuracy of radiation, and thus the warming effect of gases. Based on the latest HITRAN2020 spectroscopic data, a new 36‐band correlated k‐distribution (CKD) scheme is developed with high spectral band resolution for radiative transfer model. By considering errors of both radiative fluxes and atmospheric heating rates, optimizations are made to select the overlapping method and the number of k‐distribution quadrature points in each band. The new CKD model exhibits a remarkable improvement in heating rates and radiative fluxes relative to the previous 17‐band model when performing the identical radiative transfer calculations under 50 atmospheric profiles. The heating rate root‐mean‐square errors (RMSEs) of the 36‐band model are 0.101 and 0.075 K d−1 below 4 hPa for longwave and shortwave, respectively, when validated against the line‐by‐line benchmarks. The longwave irradiance RMSE is 0.47 W m−2 at the top of atmosphere, and the shortwave RMSE is 2.15 W m−2 at the surface. Furthermore, the cases simulating radiative forcing induced by varying gas concentrations demonstrate the ability of the 36‐band model to study the warming effect of greenhouse gases.

Global Warming Has Accelerated: Are the United Nations and the Public Well-Informed?

Global temperature leaped more than 0.4°C (0.7°F) during the past two years, the 12-month average peaking in August 2024 at +1.6°C relative to the temperature at the beginning of last century (the 1880-1920 average). This temperature jump was spurred by one of the periodic tropical El Niño warming events, but many Earth scientists were baffled by the magnitude of the global warming, which was twice as large as expected for the weak 2023-2024 El Niño. We find that most of the other half of the warming was caused by a restriction on aerosol emissions by ships, which was imposed in 2020 by the International Maritime Organization to combat the effect of aerosol pollutants on human health. Aerosols are small particles that serve as cloud formation nuclei. Their most important effect is to increase the extent and brightness of clouds, which reflect sunlight and have a cooling effect on Earth. When aerosols – and thus clouds – are reduced, Earth is darker and absorbs more sunlight, thus enhancing global warming. Ships are the main aerosol source in the North Pacific and North Atlantic Oceans. We quantify the aerosol effect from the geographical distribution of sunlight reflected by Earth as measured by satellites, with the largest expected and observed effects in the North Pacific and North Atlantic Oceans. We find that aerosol cooling, and thus climate sensitivity, are understated in the best estimate of the United Nations Intergovernmental Panel on Climate Change (IPCC). Global warming caused by reduced ship aerosols will not go away as tropical climate moves into its cool La Niña phase. Therefore, we expect that global temperature will not fall much below +1.5°C level, instead oscillating near or above that level for the next few years, which will help confirm our interpretation of the sudden global warming. High sea surface temperatures and increasing ocean hotspots will continue, with harmful effects on coral reefs and other ocean life. The largest practical effect on humans today is increase of the frequency and severity of climate extremes. More powerful tropical storms, tornadoes, and thunderstorms, and thus more extreme floods, are driven by high sea surface temperature and a warmer atmosphere that holds more water vapor. Higher global temperature also increases the intensity of heat waves and – at the times and places of dry weather – high temperature increases drought intensity, including “flash droughts” that develop rapidly, even in regions with adequate average rainfall. Polar climate change has the greatest long-term effect on humanity, with impacts accelerated by the jump in global temperature. We find that polar ice melt and freshwater injection onto the North Atlantic Ocean exceed prior estimates and, because of accelerated global warming, the melt will increase. As a result, shutdown of the Atlantic Meridional Overturning Circulation (AMOC) is likely within the next 20-30 years, unless actions are taken to reduce global warming – in contradiction to conclusions of IPCC. If AMOC is allowed to shut down, it will lock in major problems including sea level rise of several meters – thus, we describe AMOC shutdown as the “point of no return.” We suggest that an alternative perspective – a complement to the IPCC approach – is needed to assess these issues and actions that are needed to avoid handing young people a dire situation that is out of their control. This alternative approach will make more use of ongoing observations to drive modeling and more use of paleoclimate to test modeling and test our understanding. As of today, the threats of AMOC shutdown and sea level rise are poorly understood, but better observations of polar ocean and ice changes in response to the present accelerated global warming have the potential to greatly improve our understanding.

Impacto da área total e distribuição espacial da infraestrutura verde na ilha de calor urbana de dossel na Região Metropolitana de São Paulo - Um estudo numérico

Abstract A rapid verticalization to accommodate the citizens of the Metropolitan Region of São Paulo is altering the balance of radiation and atmospheric heat, highlighting the need to understand the impact that green and built infrastructure have on the canopy urban heat island phenomenon. This meteorological phenomenon occurs mainly due to the difference in landscape between urban and rural areas. Hypothetical scenarios with different green profiles were simulated using the WRF model coupled with SLUCM, and their results were compared to the current scenario using numerical data in order to observe the impact of green infrastructure. Comparison using output data showed that the total area of green infrastructure has great potential in reducing the intensity of the canopy urban heat island. The scenario with the largest total area and highest dispersion of green infrastructure recorded average urban temperatures 1.2 °C to 1.9 °C lower than the current scenario. Understanding the behavior of green infrastructure and its benefits is important for the development of municipal public policies that are in line with sustainable goals, and explicitly the relevance of urban parks and squares for local thermal regulation.

High-temperature measurements of acetylene VUV absorption cross sections and application to warm exoplanet atmospheres

Context. Most observed exoplanets have high equilibrium temperatures (Teq > 500 K). Understanding the chemistry of their atmospheres and interpreting their observations requires the use of chemical kinetic models including photochemistry. The thermal dependence of the vacuum ultraviolet (VUV) absorption cross sections of molecules used in these models is poorly known at high temperatures, leading to uncertainties in the resulting abundance profiles. Aims. The aim of our work is to study experimentally the thermal dependence of VUV absorption cross sections of molecules of interest for exoplanet atmospheres and provide accurate data for use in atmospheric models. This study focuses on acetylene (C2H2). Methods. We measured absorption cross sections of C2H2 at seven temperatures ranging from 296 to 773 K recorded in the 115–230 nm spectral domain using VUV spectroscopy and synchrotron radiation. These data were used in our 1D thermo-photochemical model, to assess their impact on the predicted composition of a generic hot Jupiter-like exoplanet atmosphere. Results. The absolute absorption cross sections of C2H2 increase with temperature. This increase is relatively constant from 115 to 185 nm and rises sharply from 185 to 230 nm. The abundance profile of C2H2 calculated using the model shows a slight variation, with a maximum decrease of 40% near 5 × 10−5 bar, when using C2H2 absorption cross sections measured at 773 K compared to those at 296 K. This is explained by the absorption, higher in the atmosphere, of the actinic flux from 150 to 230 nm due to the increase in the C2H2 absorption in this spectral range. This change also impacts the abundance profiles of other by-products such as methane (CH4) and ethylene (C2H4). Conclusions. We present the first experimental measurements of the VUV absorption cross sections of C2H2 at high temperatures. Similar studies of other major species are needed to improve our understanding of exoplanet atmospheres.

Catchments Amplify Reservoir Thermal Response to Climate Warming

AbstractLentic waters integrate atmosphere and catchment processes, and thus ultimately capture climate signals. However, studies of climate warming effects on lentic waters usually do not sufficiently account for a change in heat flux from the catchment through altered inflow temperature and discharge under climate change. This is particularly relevant for reservoirs, which are highly impacted by catchment hydrology and may be affected by upstream reservoirs or pre‐dams. This study explicitly quantified how the catchment and pre‐dams modify the thermal response of Rappbode Reservoir, Germany's largest drinking water reservoir system, to climate change. We established a catchment‐lake modeling chain in the main reservoir and its two pre‐dams utilizing the lake model GOTM, the catchment model mHM, and the stream temperature model Air2stream, forced by an ensemble of climate projections under RCP2.6 and 8.5 warming scenarios. Results exhibited a warming of 0.27/0.15°C decade−1 for the surface/bottom temperatures of the main reservoir, with approximately 8%/24% of this warming attributed to the catchment warming, respectively. The catchment warming amplified the deep water warming more than at the surface, contrary to the atmospheric warming effect, and advanced stratification by about 1 week, while having a minor impact on stratification intensity. On the other hand, pre‐dams reduced the inflow temperature into the main reservoir in spring, and consequently lowered the hypolimnetic temperature and postponed stratification onset. This shielded the main reservoir from climate warming, although overall the contribution of pre‐dams was minimal. Altogether, our study highlights the importance of catchment alterations and seasonality when projecting reservoir warming, and provides insights into catchment‐reservoir coupling under climate change.

Climatic variability as a principal driver of primary production in the southernmost subalpine Rocky Mountain lake

ABSTRACT Mountain lakes are sensitive indicators of anthropogenically driven global change, with lake sediment records documenting increased primary production during the twentieth century. Atmospheric nutrient deposition and warming have been attributed to changes in other Western mountain lakes, however, the intensity of these drivers varies. We analyzed a sediment core representing a 270-year record from Santa Fe Lake, New Mexico, to constrain the southern margin of Rocky Mountain lakes and quantify patterns of change in lake biogeochemistry, production, and diatoms since 1750. Lake sediments were dated using 210Pb and analyzed for carbon (C), nitrogen (N), stable isotopes (δ13C, δ15N), diatoms, and phototrophic pigments. The abundance of cyanobacteria, purple sulfur-reducing bacteria, and diatom pigments were elevated during the stable conditions of the Little Ice Age; these phototrophic groups declined in the late 1800s and reached a minimum by 1950. From 1950 to 2020, sediments recorded an increased abundance of cryptophyte, diatom, and chlorophyte groups. The C and N (percentage dry mass) increased after 1950, whereas δ15N and δ13C values declined. Changes since the mid-twentieth century are contemporaneous with warming trends in the Southwest and modest deposition of atmospheric N. Our findings highlight the geographic variability of mountain lake responses to changing environmental conditions.

Mediterranean marine heatwaves intensify in the presence of concurrent atmospheric heatwaves

Under climate change, temperature extremes have become more frequent and intense in recent decades, both in the atmosphere and in the ocean with devastating impacts on ecosystems and succeeding socioeconomic consequences. This is particularly true in climate change hotspots such as the Mediterranean region, where spatiotemporal compounding of extreme phenomena is becoming the norm. In the framework of a new spatiotemporal approach to heatwave detection, which tracks the evolution of the phenomena throughout their life cycle, the concurrence of marine and atmospheric heatwaves is investigated in this study. Concurrency of both phenomena in time and space shows a relevant impact on the intensity of the marine heatwaves, while no relevant changes are observed in atmospheric heat waves. Therefore, we demonstrate that intensification in extreme temperature events is accompanied by the added local intensification effect of marine heatwaves when concurring with atmospheric heatwaves, especially in recent years.

Investigating the influence of vertical moisture integrated flux convergence on rainfall recovery in the Sahel region of West Africa

The West African Sahel, situated as a semiarid transition area between the Sahara Desert and the savannah subregion, has garnered considerable research interest in recent years due to its distinctive climate characteristics. Of particular focus in this study are the patterns of moisture flux convergence and summer monsoon rainfall in the Sahel, and their interconnected variability. This study aims to enhance our comprehension of the dynamics governing the variation of the West African Monsoon (WAM) through the Vertical Integrated Moisture Flux Convergence. (VIMFC). This study findings reveal a notable upward trend in rainfall within the Sahel region over the past thirty years, primarily attributed to the climate's response to atmospheric warming. Projections indicate that, with future warming, the frequency of rainy days and the occurrence of rainfall are expected to increase in the Sahel. While the dominant circulation systems exhibit no significant deviations, the lower-level wind patterns play a crucial role in transporting moisture from the Atlantic Ocean to the Sahel. Moreover, strengthening of wind patterns at higher altitudes correlates with wetter conditions in the Sahel in the latter decades.

Enhancing the Intrinsic Stability of Nonfullerene Acceptors through Dimerization via Ring‐locking Strategy†

Comprehensive SummaryThe power conversion efficiencies (PCEs) of non‐fullerene acceptor (NFA)‐based organic solar cells (OSCs) have undergone an exciting development in recent years, but the poor intrinsic stability of exocyclic ethylene bridges in NFAs poses a significant challenge to their commercialization. In this work, we propose a new pyran‐locking strategy that can stabilize the exocyclic ethylene bridge connecting the strong electron‐deficient 2‐(3‐oxo‐2,3‐dihydroinden‐1‐ylidene)malononitrile end group, based on which two dimerized NFAs (ITBIC‐F and TBTBIC‐F) with an A‐D‐π‐A‐π‐D‐A structure have been successfully synthesized with significantly improved chemical and photochemical stabilities in comparison with traditional NFAs without the ring‐locked structure. The ITBIC‐F and TBTBIC‐F ‐based OSCs not only achieve promising PCEs of 13.03% and 10.01%, respectively, but also show good device stability; the ITBIC‐F‐based unencapsulated devices can retain 75% and 62% of their initial PCEs, respectively, under continuous heat (85 °C) and light irradiation (LED, 100 mW·cm–2) in a nitrogen atmosphere.

The Influence of Family Environment on Children's Mental Health

The influence of the family environment on children's physical and mental development has been widely discussed, but the degree of children's mental health is still insufficient, and many children fail to achieve a good mental state. If the parents create a warm family atmosphere, create a safe and warm physical environment, and let the child grow up in a relaxed and pleasant family, then the child will become very confident and cheerful. In stark contrast, children who grow up in an oppressive home are more likely to be isolated and more afraid to speak up. The analysis of this paper shows that in the process of children's physical and mental development, the role of the family environment is huge. Family environment factors are the basis of children's health psychology, and establishing a harmonious and good family environment is an important condition for cultivating children's health psychology. Based on this, this paper puts forward the following suggestions. Parents should strengthen their learning, create a harmonious family atmosphere, attach importance to frustration education, and cultivate children's emotional expression ability.

Atmospheric rivers cause warm winters and extreme heat events.

Atmospheric rivers (ARs) are narrow regions of intense water vapour transport in the Earth's atmosphere. These transient phenomena carry water from the subtropics to the mid-latitudes and polar regions1,2, making up the majority of polewards moisture transport3-5 and exerting control on the precipitation and water resources in many regions6,7. In addition to transporting moisture, ARs also transport heat, but the impact of this transport on global near-surface air temperatures has not yet been characterized. Here we show that seasons with more frequent ARs also have warmer than average temperatures in many mid-latitude regions, and that AR events are associated with temperature anomalies of 5-10 °C above the climatological mean. This is due to anomalous horizontal transport and convergence of sensible heat and moisture in the lower atmosphere, which increases both downward sensible heat flux and downwelling long-wave radiation at the surface. On an hourly timescale, over 70% of extreme warm-temperature anomalies occur within ARs in large portions of the mid-latitudes, and ARs are associated with moist and compound heatwaves in many regions worldwide, suggesting that consideration of ARs may improve predictive capability for certain extreme heat events. Our results demonstrate that ARs significantly impact air temperatures on a wide array of timescales, and that they may play a wider role in global energy transport than previously recognized.

The Strengthened Linkage between ENSO and the Eurasian Pattern since the Late 1980s

Abstract The Eurasian (EU) teleconnection pattern is an important atmospheric intrinsic mode over the extratropical Northern Hemisphere, and it has strong influence on the weather and climate over Eurasia and remote regions. Investigating factors for the EU variability is crucial and has important implications for regional climate prediction. This study reveals a remarkable influence of El Niño–Southern Oscillation (ENSO) on the EU in early winter and particularly a notable enhancement of this influence since the late 1980s. The results indicate that ENSO can lead to the vertical motion and atmospheric heating anomalies over the tropical Indian Ocean, triggering an atmospheric wave train propagating along the subtropical westerly jet and inducing an EU-like pattern over Eurasia in early winter. The interdecadal enhancement of the ENSO impact on the EU after the late 1980s may be attributable to the warming of the background mean sea surface temperature (SST) in the tropical Indian Ocean. In particular, ENSO can lead to stronger atmospheric heating and circulation anomalies over the tropical Indian Ocean via a strong air–sea interaction due to a warmer background mean SST after the late 1980s. A warmer background mean SST in the tropical Indian Ocean accelerates the subtropical westerly jet due to the thermal-wind balance, which is more favorable for the propagation of the atmospheric wave train forced by the atmospheric heating anomalies in the tropical Indian Ocean. The observed mechanisms for the enhanced impact of ENSO on the EU are also validated by numerical experiments. Significance Statement The Eurasian (EU) teleconnection pattern is an important atmospheric internal variability with significant influences on the Eurasian climate. The present study finds a remarkable relationship between the EU and ENSO in early winter, and this connection is significantly enhanced in recent decades. Thus, ENSO may serve as an important precursor signal for predicting the EU. Observational analysis and numerical experiments show that the warmer tropical Indian Ocean (TIO) plays a key role in this enhanced relationship. The warmer TIO may enhance the local air–sea interaction and accelerate the subtropical jet. The ENSO-induced anomalous disturbance over the TIO becomes stronger and can more easily propagate along the subtropical jet, exerting a strong influence on the EU especially after the late 1980s.