scholarly journals How Asian aerosols impact regional surface temperatures across the globe

2020 ◽  
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Effects ◽  
Energy Transport ◽  
Temperature Response ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Temperature Responses ◽  
Global Surface

Abstract. South and East Asian anthropogenic aerosols mostly reside in an air mass extending from the Indian Ocean to the North Pacific. Yet the surface temperature effects of Asian aerosols spread across the whole globe. Here, we remove Asian anthropogenic aerosols from two independent climate models (ECHAM6.1 and NorESM1) using the same representation of aerosols via MACv2-SP (a simple plume implementation of the 2nd version of the Max Planck Institute Aerosol Climatology). We then robustly decompose the global distribution of surface temperature responses into contributions from atmospheric energy flux changes. We find that the horizontal atmospheric energy transport strongly moderates the surface temperature response over the regions where Asian aerosols reside. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the temperature effects efficiently across the Northern hemisphere, and to a lesser extent also over the Southern hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26 ± 0.04 °C (0.22 ± 0.03 for ECHAM6.1 and 0.30 ± 0.03 °C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01 ± 0.01 for ECHAM6.1 and 0.05 ± 0.01 °C for NorESM1) and shortwave cloud (0.03 ± 0.03 for ECHAM6.1 and 0.07 ± 0.02 °C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the Northern hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and weakest during the Arctic summer. We estimate that under a strong Asian aerosol mitigation policy tied with strong climate mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years' worth of current day global warming during the next few decades.

scholarly journals How Asian aerosols impact regional surface temperatures across the globe

2021 ◽  
Vol 21 (8) ◽  
pp. 5865-5881
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Temperature Effects ◽  
Energy Transport ◽  
Temperature Response ◽  
The Arctic ◽  
Anthropogenic Aerosols ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Temperature Responses ◽  
Global Surface

Abstract. South and East Asian anthropogenic aerosols mostly reside in an air mass extending from the Indian Ocean to the North Pacific. Yet the surface temperature effects of Asian aerosols spread across the whole globe. Here, we remove Asian anthropogenic aerosols from two independent climate models (ECHAM6.1 and NorESM1) using the same representation of aerosols via MACv2-SP (a simple plume implementation of the second version of the Max Planck Institute Aerosol Climatology). We then robustly decompose the global distribution of surface temperature responses into contributions from atmospheric energy flux changes. We find that the horizontal atmospheric energy transport strongly moderates the surface temperature response over the regions where Asian aerosols reside. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the temperature effects efficiently across the Northern Hemisphere and to a lesser extent also over the Southern Hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26±0.04 ∘C (0.22±0.03 for ECHAM6.1 and 0.30±0.03 ∘C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01±0.01 for ECHAM6.1 and 0.05±0.01 ∘C for NorESM1) and shortwave cloud (0.03±0.03 for ECHAM6.1 and 0.07±0.02 ∘C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the northern-hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and weakest during the Arctic summer. We estimate that under a strong Asian aerosol mitigation policy tied with strong climate mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years' worth of current-day global warming during the next few decades.

Decomposing local and remote surface temperature impacts of Asian aerosols

2021 ◽  
Author(s):  
Joonas Merikanto ◽  
Kalle Nordling ◽  
Petri Räisänen ◽  
Jouni Räisänen ◽  
Declan O'Donnell ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Energy Transport ◽  
East Asian ◽  
Temperature Response ◽  
Longwave Radiation ◽  
Shortwave Radiation ◽  
Anthropogenic Aerosols ◽  
Anthropogenic Aerosol ◽  
Clear Sky ◽  
Temperature Responses

<p>We investigate how a regionally confined radiative forcing of South and East Asian aerosols translate into local and remote surface temperature responses across the globe. To do so, we carry out equilibrium climate simulations with and without modern day South and East Asian anthropogenic aerosols in two climate models with independent development histories (ECHAM6.1 and NorESM1).  We run the models with the same anthropogenic aerosol representations via MACv2-SP (a simple plume implementation of the 2<sup>nd</sup> version of the Max Planck Institute Aerosol Climatology). This leads to a near identical change in instantaneous direct and indirect aerosol forcing due to removal of Asian aerosols in the two models. We then robustly decompose and compare the energetic pathways that give rise to the global and regional surface temperature effects in the models by a novel temperature response decomposition method, which translated the changes in atmospheric and surface energy fluxes into surface temperature responses by using a concept of planetary emissivity.  </p><p>We find that the removal of South and East Asian anthropogenic aerosols leads to strong local warming  response from increased clear-sky shortwave radiation over the region, combined with opposing warming and cooling responses due to changes in cloud longwave and shortwave radiation. However, the local warming response is strongly modulated by the changes in horizontal atmospheric energy transport. Atmospheric energy transport and changes in clear-sky longwave radiation redistribute the surface temperature responses efficiently across the Northern hemisphere, and to a lesser extent also over the Southern hemisphere. The model-mean global surface temperature response to Asian anthropogenic aerosol removal is 0.26±0.04 °C (0.22±0.03 for ECHAM6.1 and 0.30±0.03 °C for NorESM1) of warming. Model-to-model differences in global surface temperature response mainly arise from differences in longwave cloud (0.01±0.01 for ECHAM6.1 and 0.05±0.01 °C for NorESM1) and shortwave cloud (0.03±0.03 for ECHAM6.1 and 0.07±0.02 °C for NorESM1) responses. The differences in cloud responses between the models also dominate the differences in regional temperature responses. In both models, the Northern hemispheric surface warming amplifies towards the Arctic, where the total temperature response is highly seasonal and modulated by seasonal changes in oceanic heat exchange and clear-sky longwave radiation.</p><p>We estimate that under a strong Asian aerosol mitigation policy tied with strong greenhouse gas mitigation (Shared Socioeconomic Pathway 1-1.9) the Asian aerosol reductions can add around 8 years’ worth of current day global warming during the next few decades.</p>

Arctic climate response to extreme events in synoptic and planetary scale atmospheric energy transport

2020 ◽  
Author(s):  
Johanne H. Rydsaa ◽  
Rune G. Graversen ◽  
Patrick Stoll
Keyword(s):  
Energy Transport ◽  
Winter Season ◽  
Arctic Climate ◽  
The Arctic ◽  
Synoptic Scale ◽  
Near Surface ◽  
Latent Energy ◽  
Atmospheric Energy ◽  
Planetary Scale ◽  
Atmospheric Energy Transport

<p>Atmospheric energy transport into the Arctic (>70° N) has been shown to greatly alter the Arctic temperatures and the development of the Arctic weather and climate. Recent research suggests that latent energy transport into the Arctic by large, planetary-scale atmospheric systems cause a stronger and more long-lasting impact on near surface temperatures, than energy transported by smaller, synoptic scale systems. This implies that Rossby waves impact Arctic climate more than synoptic cyclones. Therefore, shifts in circulation patterns driving atmospheric energy transport into the Arctic on different scales have a potential to change Arctic climate.</p><p>Here, we show that the annual mean impact of latent energy transport on Arctic temperatures is dominated by the winter season transport. Furthermore, by examining the ERA5 dataset for the years 1979-2018, we find that over the past four decades, there has been a shift in the mean winter season latent energy transport, from smaller, synoptic scale systems (-0.03 PW/decade), towards larger, planetary scale systems (+0.05 PW/decade) which as mentioned, have a larger climatic impact. As a consequence, this shift is estimated to have increased the Arctic temperatures. We find that the trends are driven by an increase in the extreme transport events (here we examine the upper 97.5<sup>th</sup> percentile). The upper extremes have increased more than the average on the planetary scale, and decreased more on the synoptic scale. The decrease in extreme synoptic scale transport at 70° N has been confirmed in other analyses of high vorticity weather systems. By examining the extreme transport events on seasonal scales, we reveal differences in the temporal distribution of planetary vs. synoptic scale extreme events, and identify areas of the Arctic that receive the strongest impact with respect to increases in near-surface temperatures.</p>

Relative Contributions of Atmospheric Energy Transport and Sea Ice Loss to the Recent Warm Arctic Winter

2017 ◽  
Vol 30 (18) ◽  
pp. 7441-7450 ◽  
Author(s):  
Hye-Mi Kim ◽  
Baek-Min Kim
Keyword(s):  
Sea Ice ◽  
Energy Transport ◽  
Open Water ◽  
The Arctic ◽  
Arctic Warming ◽  
Atmospheric Energy ◽  
Downward Longwave Radiation ◽  
Ice Retreat ◽  
Atmospheric Energy Transport ◽  
Heat And Moisture

Abstract The relative contributions of atmospheric energy transport (via heat and moisture advection) and sea ice decline to recent Arctic warming were investigated using high-resolution reanalysis data up to 2017. During the Arctic winter, a variation of downward longwave radiation (DLR) is fundamental in modulating Arctic surface temperature. In the warm Arctic winter, DLR and precipitable water (PW) are increasing over the entire Arctic; however, the major drivers for such increases differ regionally. In areas such as the northern Greenland Sea, increasing DLR and PW are caused mainly by convergence of atmospheric energy transport from lower latitudes. In regions of maximum sea ice retreat (e.g., northern Barents–Kara Seas), continued sea ice melting from previous seasons drive the DLR and PW increases, consistent with the positive ice–insulation feedback. Distinct local feedbacks between open water and ice-retreat regions were further compared. In open water regions, a reduced ocean–atmosphere temperature gradient caused by atmospheric warming suppresses surface turbulent heat flux (THF) release from the ocean to the atmosphere; thus, surface warming cannot accelerate. Conversely, in ice-retreat regions, sea ice reduction allows the relatively warm ocean to interact with the colder atmosphere via surface THF release. This increases temperature and humidity in the lower troposphere consistent with the positive ice–insulation feedback. The implication of this study is that Arctic warming will slow as the open water fraction increases. Therefore, given sustained greenhouse warming, the roles of atmospheric heat and moisture transport from lower latitudes are likely to become increasingly critical in the future Arctic climate.

scholarly journals Understanding the surface temperature response and its uncertainty to CO<sub>2</sub>, CH<sub>4</sub>, black carbon, and sulfate

2021 ◽  
Vol 21 (19) ◽  
pp. 14941-14958
Author(s):  
Kalle Nordling ◽  
Hannele Korhonen ◽  
Jouni Räisänen ◽  
Antti-Ilari Partanen ◽  
Bjørn H. Samset ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Black Carbon ◽  
Surface Albedo ◽  
Climate Models ◽  
Temperature Response ◽  
Regional Model ◽  
Climate Forcing ◽  
Clear Sky ◽  
Temperature Responses ◽  
Global Surface

Abstract. Understanding the regional surface temperature responses to different anthropogenic climate forcing agents, such as greenhouse gases and aerosols, is crucial for understanding past and future regional climate changes. In modern climate models, the regional temperature responses vary greatly for all major forcing agents, but the causes of this variability are poorly understood. Here, we analyze how changes in atmospheric and oceanic energy fluxes due to perturbations in different anthropogenic climate forcing agents lead to changes in global and regional surface temperatures. We use climate model data on idealized perturbations in four major anthropogenic climate forcing agents (CO2, CH4, sulfate, and black carbon aerosols) from Precipitation Driver Response Model Intercomparison Project (PDRMIP) climate experiments for six climate models (CanESM2, HadGEM2-ES, NCAR-CESM1-CAM4, NorESM1, MIROC-SPRINTARS, GISS-E2). Particularly, we decompose the regional energy budget contributions to the surface temperature responses due to changes in longwave and shortwave fluxes under clear-sky and cloudy conditions, surface albedo changes, and oceanic and atmospheric energy transport. We also analyze the regional model-to-model temperature response spread due to each of these components. The global surface temperature response stems from changes in longwave emissivity for greenhouse gases (CO2 and CH4) and mainly from changes in shortwave clear-sky fluxes for aerosols (sulfate and black carbon). The global surface temperature response normalized by effective radiative forcing is nearly the same for all forcing agents (0.63, 0.54, 0.57, 0.61 K W−1 m2). While the main physical processes driving global temperature responses vary between forcing agents, for all forcing agents the model-to-model spread in temperature responses is dominated by differences in modeled changes in longwave clear-sky emissivity. Furthermore, in polar regions for all forcing agents the differences in surface albedo change is a key contributor to temperature responses and its spread. For black carbon, the modeled differences in temperature response due to shortwave clear-sky radiation are also important in the Arctic. Regional model-to-model differences due to changes in shortwave and longwave cloud radiative effect strongly modulate each other. For aerosols, clouds play a major role in the model spread of regional surface temperature responses. In regions with strong aerosol forcing, the model-to-model differences arise from shortwave clear-sky responses and are strongly modulated by combined temperature responses to oceanic and atmospheric heat transport in the models.

scholarly journals Isolating the Temperature Feedback Loop and Its Effects on Surface Temperature

2016 ◽  
Vol 73 (8) ◽  
pp. 3287-3303 ◽  
Author(s):  
Sergio A. Sejas ◽  
Ming Cai
Keyword(s):  
Surface Temperature ◽  
Feedback Loop ◽  
Temperature Response ◽  
Feedback Loops ◽  
The Arctic ◽  
Response Analysis ◽  
Surface Warming ◽  
Temperature Feedback ◽  
The Tropics ◽  
Temperature Responses

Abstract Climate feedback processes are known to substantially amplify the surface warming response to an increase of greenhouse gases. When the forcing and feedbacks modify the temperature response they trigger temperature feedback loops that amplify the direct temperature changes due to the forcing and nontemperature feedbacks through the thermal–radiative coupling between the atmosphere and surface. This study introduces a new feedback-response analysis method that can isolate and quantify the effects of the temperature feedback loops of individual processes on surface temperature from their corresponding direct surface temperature responses. The authors analyze a 1% yr−1 increase of CO2 simulation of the NCAR CCSM4 at the time of CO2 doubling to illustrate the new method. The Planck sensitivity parameter, which indicates colder regions experience stronger surface temperature responses given the same change in surface energy flux, is the inherent factor that leads to polar warming amplification (PWA). This effect explains the PWA in the Antarctic, while the direct temperature response to the albedo and cloud feedbacks further explains the greater PWA of the Arctic. Temperature feedback loops, particularly the one associated with the albedo feedback, further amplify the Arctic surface warming relative to the tropics. In the tropics, temperature feedback loops associated with the CO2 forcing and water vapor feedback cause most of the surface warming. Overall, the temperature feedback is responsible for most of the surface warming globally, accounting for nearly 76% of the global-mean surface warming. This is 3 times larger than the next largest warming contribution, indicating that the temperature feedback loop is the preeminent contributor to the surface warming.

scholarly journals Seasonal Dependence of the Effect of Arctic Greening on Tropical Precipitation

2015 ◽  
Vol 28 (15) ◽  
pp. 6086-6095 ◽  
Author(s):  
Sarah M. Kang ◽  
Baek-Min Kim ◽  
Dargan M. W. Frierson ◽  
Su-Jong Jeong ◽  
Jeongbin Seo ◽  
...  
Keyword(s):  
Energy Transport ◽  
Longwave Radiation ◽  
The Arctic ◽  
Boreal Winter ◽  
Net Energy ◽  
Atmospheric Energy ◽  
Arctic Vegetation ◽  
Tropical Precipitation ◽  
Atmospheric Energy Transport ◽  
Seasonal Dependence

Abstract This paper examines the seasonal dependence of the effect of Arctic greening on tropical precipitation. In CAM3/CLM3 coupled to a mixed layer ocean, shrub and grasslands poleward of 60°N are replaced with boreal forests. With darker Arctic vegetation, the absorption of solar energy increases, but primarily in boreal spring and summer since little insolation reaches the Arctic in boreal winter. The net energy input into the northern extratropics is partly balanced by southward atmospheric energy transport across the equator by an anomalous Hadley circulation, resulting in a northward shift of the tropical precipitation. In contrast, in boreal fall, the slight increase in insolation over the Arctic is more than offset by increased outgoing longwave radiation and reduced surface turbulent fluxes in midlatitudes, from the warmer atmosphere. As a result, the Northern Hemisphere atmosphere loses energy, which is compensated by a northward cross-equatorial atmospheric energy transport, leading to a southward shift of the tropical precipitation in boreal fall. Thus, although Arctic vegetation is changed throughout the year, its effect on tropical precipitation exhibits substantial seasonal variations.

scholarly journals On the Role of the Atmospheric Energy Transport in 2 × CO2–Induced Polar Amplification in CESM1

2019 ◽  
Vol 32 (13) ◽  
pp. 3941-3956 ◽  
Author(s):  
Rune G. Graversen ◽  
Peter L. Langen
Keyword(s):  
Global Warming ◽  
Southern Hemisphere ◽  
Energy Transport ◽  
The Arctic ◽  
Polar Regions ◽  
Antarctic Region ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
The Antarctic ◽  
Co2 Forcing

AbstractA doubling of the atmospheric CO2 content leads to global warming that is amplified in the polar regions. The CO2 forcing also leads to a change of the atmospheric energy transport. This transport change affects the local warming induced by the CO2 forcing. Using the Community Earth System Model (CESM), the direct response to the transport change is investigated. Divergences of the transport change associated with a CO2 doubling are implemented as a forcing in the 1 × CO2 preindustrial control climate. This forcing is zero in the global mean. In response to a CO2 increase in CESM, the northward atmospheric energy transport decreases at the Arctic boundary. However, the transport change still leads to a warming of the Arctic. This is due to a shift between dry static and latent transport components, so that although the dry static transport decreases, the latent transport increases at the Arctic boundary, which is consistent with other model studies. Because of a greenhouse effect associated with the latent transport, the cooling caused by a change of the dry static component is more than compensated for by the warming induced by the change of the latent transport. Similar results are found for the Antarctic region, but the transport change is larger in the Southern Hemisphere than in its northern counterpart. As a consequence, the Antarctic region warms to the extent that this warming leads to global warming that is likely enhanced by the surface albedo feedback associated with considerable ice retreat in the Southern Hemisphere.

scholarly journals Atmospheric energy transport to the Arctic 1979–2012

2015 ◽  
Vol 67 (1) ◽  
pp. 25482 ◽  
Author(s):  
Song-Miao Fan ◽  
Lucas M. Harris ◽  
Larry W. Horowitz
Keyword(s):  
Energy Transport ◽  
The Arctic ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport

Investigating tropical and midlatitude drivers of Arctic atmospheric energy transport

2020 ◽  
Author(s):  
Etienne Dunn-Sigouin ◽  
Camille Li ◽  
Paul Kushner
Keyword(s):  
Planetary Wave ◽  
Energy Transport ◽  
Warm Pool ◽  
Planetary Waves ◽  
The Arctic ◽  
Symmetric Model ◽  
Atmospheric Energy ◽  
Tropical Warm Pool ◽  
Wave Transport ◽  
Atmospheric Energy Transport

&lt;p&gt;Planetary waves with zonal wavenumbers k &amp;#8804; 3 dominate poleward atmospheric energy transport and its associated Arctic warming and moistening impacts in reanalysis data. Previous work suggests planetary waves generated by tropical warm pool Sea-Surface Temperatures (SSTs) and midlatitude synoptic waves (k &amp;#8805; 4) can drive Arctic energy transport. Here, we investigate tropical and midlatitude drivers of Arctic planetary wave transport using an idealised aquaplanet model. First, we show that the zonally-symmetric model qualitatively captures the main characteristics of observed planetary wave transport, as well as its impacts in the Arctic. Next, we show that an idealised tropical warm pool, driven by regional SST forcing, amplifies but is not the dominant source of Arctic planetary wave transport. Finally, lag-regressions using reanalysis and model data suggest midlatitude synoptic waves compensate rather than drive Arctic planetary wave transport. The results do not support the simple geometric effect of midlatitude synoptic waves aliasing onto Arctic planetary waves on a sphere, but rather point towards more complex scale interactions and local drivers of Arctic planetary wave transport.&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document