Springtime atmospheric energy transport and the control of Arctic summer sea-ice extent

2013 ◽  
Vol 3 (8) ◽  
pp. 744-748 ◽  
Author(s):  
Marie-Luise Kapsch ◽  
Rune Grand Graversen ◽  
Michael Tjernström
Keyword(s):  
Sea Ice ◽  
Energy Transport ◽  
Sea Ice Extent ◽  
Atmospheric Energy ◽  
Atmospheric Energy Transport ◽  
Arctic Summer

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 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 Well Do the CMIP5 Models Simulate the Antarctic Atmospheric Energy Budget?

2015 ◽  
Vol 28 (20) ◽  
pp. 7933-7942 ◽  
Author(s):  
Michael Previdi ◽  
Karen L. Smith ◽  
Lorenzo M. Polvani
Keyword(s):  
Sea Ice ◽  
Energy Budget ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Cmip5 Models ◽  
Secondary Importance ◽  
Sea Ice Extent ◽  
Atmospheric Energy ◽  
The Antarctic

Abstract The authors evaluate 23 coupled atmosphere–ocean general circulation models from phase 5 of CMIP (CMIP5) in terms of their ability to simulate the observed climatological mean energy budget of the Antarctic atmosphere. While the models are shown to capture the gross features of the energy budget well [e.g., the observed two-way balance between the top-of-atmosphere (TOA) net radiation and horizontal convergence of atmospheric energy transport], the simulated TOA absorbed shortwave (SW) radiation is too large during austral summer. In the multimodel mean, this excessive absorption reaches approximately 10 W m−2, with even larger biases (up to 25–30 W m−2) in individual models. Previous studies have identified similar climate model biases in the TOA net SW radiation at Southern Hemisphere midlatitudes and have attributed these biases to errors in the simulated cloud cover. Over the Antarctic, though, model cloud errors are of secondary importance, and biases in the simulated TOA net SW flux are instead driven mainly by biases in the clear-sky SW reflection. The latter are likely related in part to the models’ underestimation of the observed annual minimum in Antarctic sea ice extent, thus underscoring the importance of sea ice in the Antarctic energy budget. Finally, substantial differences in the climatological surface energy fluxes between existing observational datasets preclude any meaningful assessment of model skill in simulating these fluxes.

scholarly journals Using Atmospheric Energy Transport to Quantitatively Constrain South Pacific Convergence Zone Shifts during ENSO

2019 ◽  
Vol 32 (6) ◽  
pp. 1839-1855 ◽  
Author(s):  
Benjamin R. Lintner ◽  
William R. Boos
Keyword(s):  
Energy Source ◽  
Energy Transport ◽  
El Nino ◽  
South Pacific ◽  
Radiative Flux ◽  
South Pacific Convergence Zone ◽  
Convergence Zone ◽  
Atmospheric Energy ◽  
Enso Events ◽  
Atmospheric Energy Transport

AbstractThe South Pacific convergence zone (SPCZ) exhibits well-known spatial displacements in response to anomalous sea surface temperatures (SSTs) associated with the El Niño–Southern Oscillation (ENSO). Although dynamic and thermodynamic changes during ENSO events are consistent with observed SPCZ shifts, explanations for these displacements have been largely qualitative. This study applies a theoretical framework based on generalizing arguments about the relationship between the zonal-mean intertropical convergence zone (ITCZ) and atmospheric energy transport (AET) to 2D, permitting quantification of SPCZ displacements during ENSO. Using either resolved atmospheric energy fluxes or estimates of column-integrated moist energy sources, this framework predicts well the observed SPCZ shifts during ENSO, at least when anomalous ENSO-region SSTs are relatively small. In large-amplitude ENSO events, such as the 1997/98 El Niño, the framework breaks down because of the large change in SPCZ precipitation intensity. The AET framework permits decomposition of the ENSO forcing into various components, such as column radiative heating versus surface turbulent fluxes, and local versus remote contributions. Column energy source anomalies in the equatorial central and eastern Pacific dominate the SPCZ shift. Furthermore, although the radiative flux anomaly is larger than the surface turbulent flux anomaly in the SPCZ region, the radiative flux anomaly, which can be viewed as a feedback on the ENSO forcing, accounts for slightly less than half of SPCZ precipitation anomalies during ENSO. This study also introduces an idealized analytical model used to illustrate AET anomalies during ENSO and to obtain a scaling for the SPCZ response to an anomalous equatorial energy source.

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>

scholarly journals Bridging perspectives from remote Sensing and Inuit communities on changing Sea-ice cover in the Baffin Bay region

2006 ◽  
Vol 44 ◽  
pp. 433-438 ◽  
Author(s):  
Walter N. Meier ◽  
Julienne Stroeve ◽  
Shari Gearheard
Keyword(s):  
Remote Sensing ◽  
Sea Ice ◽  
Local Level ◽  
Indigenous Communities ◽  
Passive Microwave ◽  
Regional Variability ◽  
Sea Ice Extent ◽  
Baffin Bay ◽  
Inuit Knowledge ◽  
Arctic Summer

AbstractPassive microwave imagery indicates a decreasing trend in Arctic Summer Sea-ice extent Since 1979. The Summers of 2002–05 have exhibited particularly reduced extent and have reinforced the downward trend. Even the winter periods have now Shown decreasing trends. At the local level, Arctic residents are also noticing changes in Sea ice. In particular, indigenous elders and hunters report changes Such as earlier break-up, later freeze-up and thinner ice. The changing conditions have profound implications for Arctic-wide climate, but there is also regional variability in the extent trends. These can have important ramifications for wildlife and indigenous communities in the affected regions. Here we bring together observations from remote Sensing with observations and knowledge of Inuit who live in the Baffin Bay region. Weaving the complementary perspectives of Science and Inuit knowledge, we investigate the processes driving changes in Baffin Bay Sea-ice extent and discuss the present and potential future effects of changing Sea ice on local activities.

scholarly journals Tropical Pacific–Driven Decadel Energy Transport Variability

2005 ◽  
Vol 18 (12) ◽  
pp. 2037-2051 ◽  
Author(s):  
Wilco Hazeleger ◽  
Camiel Severijns ◽  
Richard Seager ◽  
Franco Molteni
Keyword(s):  
Heat Transport ◽  
Energy Transport ◽  
Decadal Variability ◽  
Tropical Pacific ◽  
Ocean Heat Transport ◽  
Atmospheric Energy ◽  
The Mean ◽  
Atmospheric Energy Transport ◽  
Hadley Cells ◽  
The Tropical Pacific

Abstract The atmospheric energy transport variability associated with decadal sea surface temperature variability in the tropical Pacific is studied using an atmospheric primitive equation model coupled to a slab mixed layer. The decadal variability is prescribed as an anomalous surface heat flux that represents the reduced ocean heat transport in the tropical Pacific when it is anomalously warm. The atmospheric energy transport increases and compensates for the reduced ocean heat transport. Increased transport by the mean meridional overturning (i.e., the strengthening of the Hadley cells) causes increased poleward energy transport. The subtropical jets increase in strength and shift equatorward, and in the midlatitudes the transients are affected. NCEP–NCAR reanalysis data show that the warming of the tropical Pacific in the 1980s compared to the early 1970s seems to have caused very similar changes in atmospheric energy transport indicating that these atmospheric transport variations were driven from the tropical Pacific. To study the implication of these changes for the coupled climate system an ocean model is driven with winds obtained from the atmosphere model. The poleward ocean heat transport increased when simulated wind anomalies associated with decadal tropical Pacific variability were used, showing a negative feedback between decadal variations in the mean meridional circulation in the atmosphere and in the Pacific Ocean. The Hadley cells and subtropical cells act to stabilize each other on the decadal time scale.

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.

scholarly journals The Effect of Downwelling Longwave and Shortwave Radiation on Arctic Summer Sea Ice

2016 ◽  
Vol 29 (3) ◽  
pp. 1143-1159 ◽  
Author(s):  
Marie-Luise Kapsch ◽  
Rune Grand Graversen ◽  
Michael Tjernström ◽  
Richard Bintanja
Keyword(s):  
Sea Ice ◽  
Early Summer ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Atmospheric Conditions ◽  
Sea Ice Extent ◽  
Climate Fluctuations ◽  
Ice Melt ◽  
Different Seasons ◽  
Arctic Summer

Abstract The Arctic summer sea ice has diminished fast in recent decades. A strong year-to-year variability on top of this trend indicates that sea ice is sensitive to short-term climate fluctuations. Previous studies show that anomalous atmospheric conditions over the Arctic during spring and summer affect ice melt and the September sea ice extent (SIE). These conditions are characterized by clouds, humidity, and heat anomalies that all affect downwelling shortwave (SWD) and longwave (LWD) radiation to the surface. In general, positive LWD anomalies are associated with cloudy and humid conditions, whereas positive anomalies of SWD appear under clear-sky conditions. Here the effect of realistic anomalies of LWD and SWD on summer sea ice is investigated by performing experiments with the Community Earth System Model. The SWD and LWD anomalies are studied separately and in combination for different seasons. It is found that positive LWD anomalies in spring and early summer have significant impact on the September SIE, whereas winter anomalies show only little effect. Positive anomalies in spring and early summer initiate an earlier melt onset, hereby triggering several feedback mechanisms that amplify melt during the succeeding months. Realistic positive SWD anomalies appear only important if they occur after the melt has started and the albedo is significantly reduced relative to winter conditions. Simulations where both positive LWD and negative SWD anomalies are implemented simultaneously, mimicking cloudy conditions, reveal that clouds during spring have a significant impact on summer sea ice while summer clouds have almost no effect.

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