Arctic Amplification Weakens the Variability of Daily Temperatures over Northern Mid-to-High Latitudes

2020 ◽  
pp. 1-44
Author(s):  
Aiguo Dai ◽  
Jiechun Deng
Keyword(s):  
Sea Ice ◽  
Coupled Model ◽  
Meridional Wind ◽  
Cold Season ◽  
Temperature Variability ◽  
Tropospheric Temperature ◽  
High Latitudes ◽  
Arctic Amplification ◽  
Thermal Advection ◽  
Northern Latitudes

AbstractArctic amplification (AA) reduces meridional temperature gradients (dT/dy) over the northern mid-high latitudes, which may weaken westerly winds. It is suggested that this may lead to wavier and more extreme weather in midlatitudes. However, temperature variability is shown to decrease over northern mid-high latitudes under increasing greenhouse gases due to reduced dT/dy. Here, through analyses of coupled model simulations and ERA5 reanalysis, it is shown that consistent with previous studies cold-season surface and lower-mid tropospheric temperature (T) variability decreases over northern mid-high latitudes even in simulations with suppressed AA and sea-ice loss under increasing CO2; however, AA and sea-ice loss further reduce the T variability greatly, leading to a narrower probability distribution and weaker cold or warm extreme events relative to future mean climate. Increased CO2 strengthens meridional wind (v) with a wavenumer-4 pattern but weakens meridional thermal advection (-v dT/dy) over most northern mid-high latitudes, and AA weakens the climatological v and (-v dT/dy). The weakened thermal advection and its decreased variance are the primary cause of the T variability decrease, which is enlarged by a positive feedback between the variability of T and (-v dT/dy). AA not only reduces dT/dy, but also its variance, which further decreases T variability through (-v dT/dy). While the mean snow and ice cover decreases, its variability increases over many northern latitudes, and these changes do not weaken the T variability. Thus, AA’s influence on midlatitude temperature variability comes mainly from its impact on thermal advection, rather than on winds as previously thought.

scholarly journals Footprint of greenhouse forcing in daily temperature variability

2021 ◽  
Vol 118 (32) ◽  
pp. e2103294118
Author(s):  
Maximilian Kotz ◽  
Leonie Wenz ◽  
Anders Levermann
Keyword(s):  
High Frequency ◽  
Climate Models ◽  
Coupled Model ◽  
Climatic Conditions ◽  
Temperature Variability ◽  
Daily Temperature ◽  
Global Changes ◽  
High Latitudes ◽  
Protection Measures ◽  
Daily Variability

Changes in mean climatic conditions will affect natural and societal systems profoundly under continued anthropogenic global warming. Changes in the high-frequency variability of temperature exert additional pressures, yet the effect of greenhouse forcing thereon has not been fully assessed or identified in observational data. Here, we show that the intramonthly variability of daily surface temperature changes with distinct global patterns as greenhouse gas concentrations rise. In both reanalyses of historical observations and state-of-the-art projections, variability increases at low to mid latitudes and decreases at northern mid to high latitudes with enhanced greenhouse forcing. These latitudinally polarized daily variability changes are identified from internal climate variability using a recently developed signal-to-noise-maximizing pattern-filtering technique. Analysis of a multimodel ensemble from the Coupled Model Intercomparison Project Phase 6 shows that these changes are attributable to enhanced greenhouse forcing. By the end of the century under a business-as-usual emissions scenario, daily temperature variability would continue to increase by up to a further 100% at low latitudes and decrease by 40% at northern high latitudes. Alternative scenarios demonstrate that these changes would be limited by mitigation of greenhouse gases. Moreover, global changes in daily variability exhibit strong covariation with warming across climate models, suggesting that the equilibrium climate sensitivity will also play a role in determining the extent of future variability changes. This global response of the high-frequency climate system to enhanced greenhouse forcing is likely to have strong and unequal effects on societies, economies, and ecosystems if mitigation and protection measures are not taken.

scholarly journals An inter-hemispheric seasonal comparison of polar amplification using radiative forcing of a quadrupling CO<sub>2</sub> experiment

2020 ◽  
Vol 38 (5) ◽  
pp. 1123-1138
Author(s):  
Fernanda Casagrande ◽  
Ronald Buss de Souza ◽  
Paulo Nobre ◽  
Andre Lanfer Marquez
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
Radiative Forcing ◽  
Climate Models ◽  
Cold Season ◽  
Coupled Processes ◽  
The Arctic ◽  
Polar Regions ◽  
High Latitudes ◽  
Polar Amplification

Abstract. The numerical climate simulations from the Brazilian Earth System Model (BESM) are used here to investigate the response of the polar regions to a forced increase in CO2 (Abrupt-4×CO2) and compared with Coupled Model Intercomparison Project phase 5 (CMIP5) and 6 (CMIP6) simulations. The main objective here is to investigate the seasonality of the surface and vertical warming as well as the coupled processes underlying the polar amplification, such as changes in sea ice cover. Polar regions are described as the most climatically sensitive areas of the globe, with an enhanced warming occurring during the cold seasons. The asymmetry between the two poles is related to the thermal inertia and the coupled ocean–atmosphere processes involved. While at the northern high latitudes the amplified warming signal is associated with a positive snow– and sea ice–albedo feedback, for southern high latitudes the warming is related to a combination of ozone depletion and changes in the wind pattern. The numerical experiments conducted here demonstrated very clear evidence of seasonality in the polar amplification response as well as linkage with sea ice changes. In winter, for the northern high latitudes (southern high latitudes), the range of simulated polar warming varied from 10 to 39 K (−0.5 to 13 K). In summer, for northern high latitudes (southern high latitudes), the simulated warming varies from 0 to 23 K (0.5 to 14 K). The vertical profiles of air temperature indicated stronger warming at the surface, particularly for the Arctic region, suggesting that the albedo–sea ice feedback overlaps with the warming caused by meridional transport of heat in the atmosphere. The latitude of the maximum warming was inversely correlated with changes in the sea ice within the model's control run. Three climate models were identified as having high polar amplification for the Arctic cold season (DJF): IPSL-CM6A-LR (CMIP6), HadGEM2-ES (CMIP5) and CanESM5 (CMIP6). For the Antarctic, in the cold season (JJA), the climate models identified as having high polar amplification were IPSL-CM6A-LR (CMIP6), CanESM5(CMIP6) and FGOALS-s2 (CMIP5). The large decrease in sea ice concentration is more evident in models with great polar amplification and for the same range of latitude (75–90∘ N). Also, we found, for models with enhanced warming, expressive changes in the sea ice annual amplitude with outstanding ice-free conditions from May to December (EC-Earth3-Veg) and June to December (HadGEM2-ES). We suggest that the large bias found among models can be related to the differences in each model to represent the feedback process and also as a consequence of each distinct sea ice initial condition. The polar amplification phenomenon has been observed previously and is expected to become stronger in the coming decades. The consequences for the atmospheric and ocean circulation are still subject to intense debate in the scientific community.

scholarly journals The emergence of surface-based Arctic amplification

2009 ◽  
Vol 3 (1) ◽  
pp. 11-19 ◽  
Author(s):  
M. C. Serreze ◽  
A. P. Barrett ◽  
J. C. Stroeve ◽  
D. N. Kindig ◽  
M. M. Holland
Keyword(s):  
Sea Ice ◽  
21St Century ◽  
Lower Troposphere ◽  
Cold Season ◽  
The Arctic ◽  
Arctic Amplification ◽  
Sea Ice Extent ◽  
Air Temperatures ◽  
The Arctic Ocean ◽  
Heat Transfers

Abstract. Rises in surface and lower troposphere air temperatures through the 21st century are projected to be especially pronounced over the Arctic Ocean during the cold season. This Arctic amplification is largely driven by loss of the sea ice cover, allowing for strong heat transfers from the ocean to the atmosphere. Consistent with observed reductions in sea ice extent, fields from both the NCEP/NCAR and JRA-25 reanalyses point to emergence of surface-based Arctic amplification in the last decade.

scholarly journals Emergent Constraints in Climate Projections: A Case Study of Changes in High-Latitude Temperature Variability

2017 ◽  
Vol 30 (10) ◽  
pp. 3655-3670 ◽  
Author(s):  
Aleksandra Borodina ◽  
Erich M. Fischer ◽  
Reto Knutti
Keyword(s):  
Sea Ice ◽  
Coupled Model ◽  
Temperature Variability ◽  
Climate Projections ◽  
Underlying Assumption ◽  
Aggregate Information ◽  
Emergent Constraints ◽  
Realistic Representation ◽  
Ice Retreat ◽  
Sea Ice Retreat

Abstract Climate projections from phase 5 of the Coupled Model Intercomparison Project (CMIP5) ensemble show a decrease in interannual surface temperature variability over high latitudes with a large intermodel spread, in particular over the areas of sea ice retreat. Here relationships are found between the models’ present-day performance in sea ice–related metrics and future changes in temperature variability. These relations, so-called emergent constraints, can produce ensembles of models calibrated with present-day observations with a narrower spread across their members than across the full ensemble. The underlying assumption is that models in better agreement with observations or reanalyses in a carefully selected metric probably have a more realistic representation of local processes, and therefore are more reliable for projections. Thus, the reliability of this method depends on the availability of high-quality observations or reanalyses. This work represents a step toward formalization of the emergent constraints framework, as so far there is no consensus on how the constraints should be best implemented. The authors quantify the reduction in spread from emerging constraints for various metrics and their combinations, different emission scenarios, and seasons. Some of the general features of emerging constraints are discussed, and how to effectively aggregate information across metrics and seasons to achieve the largest reduction in model spread. It is demonstrated, based on the case of temperature variability, that a robust constraint can be obtained by combining relevant metrics across all seasons. Such a constraint results in a strongly reduced spread across model projections, which is consistent with a process understanding of variability changes due to sea ice retreat.

scholarly journals Changes of Variability in Response to Increasing Greenhouse Gases. Part I: Temperature

2007 ◽  
Vol 20 (21) ◽  
pp. 5455-5467 ◽  
Author(s):  
R. J. Stouffer ◽  
R. T. Wetherald
Keyword(s):  
Sea Ice ◽  
Surface Temperature ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Annual Data ◽  
Tropospheric Temperature ◽  
High Latitudes ◽  
Near Surface ◽  
Temperature Variance ◽  
General Reduction

Abstract This study documents the temperature variance change in two different versions of a coupled ocean–atmosphere general circulation model forced with estimates of future increases of greenhouse gas (GHG) and aerosol concentrations. The variance changes are examined using an ensemble of 8 transient integrations for the older model version and 10 transient integrations for the newer one. Monthly and annual data are used to compute the mean and variance changes. Emphasis is placed upon computing and analyzing the variance changes for the middle of the twenty-first century and compared with those found in a control integration. The large-scale variance of lower-tropospheric temperature (including surface air temperature) generally decreases in high latitudes particularly during fall due to a delayed onset of sea ice as the climate warms. Sea ice acts to insolate the atmosphere from the much larger heat capacity of the ocean. Therefore, the near-surface temperature variance tends to be larger over the sea ice–covered regions, than the nearby ice-free regions. The near-surface temperature variance also decreases during the winter and spring due to a general reduction in the extent of sea ice during winter and spring. Changes in storminess were also examined and were found to have relatively little effect upon the reduction of temperature variance. Generally small changes of surface air temperature variance occurred in low and midlatitudes over both land and oceanic areas year-round. An exception to this was a general reduction of variance in the equatorial Pacific Ocean for the newer model. Small increases in the surface air temperature variance occur in mid- to high latitudes during the summer months, suggesting the possibility of more frequent and longer-lasting heat waves in response to increasing GHGs.

Arctic amplification as a rapid response to increased CO2

2021 ◽  
Author(s):  
Tyler Janoski ◽  
Michael Previdi ◽  
Gabriel Chiodo ◽  
Karen Smith ◽  
Lorenzo Polvani
Keyword(s):  
Sea Ice ◽  
General Circulation ◽  
Coupled Model ◽  
General Circulation Models ◽  
Forced Response ◽  
Arctic Sea Ice ◽  
Lapse Rate ◽  
The Arctic ◽  
Cmip5 Models ◽  
Arctic Amplification

&lt;p&gt;Arctic amplification (AA), or enhanced surface warming of the Arctic, is ubiquitous in observations, and in model simulations subjected to increased greenhouse gas (GHG) forcing. Despite its importance, the mechanisms driving AA are not entirely understood. Here, we show that in CMIP5 (Coupled Model Intercomparison Project 5) general circulation models (GCMs), AA develops within a few months following an instantaneous quadrupling of atmospheric CO&lt;sub&gt;2&lt;/sub&gt;. We find that this rapid AA response can be attributed to the lapse rate feedback, which acts to disproportionately warm the Arctic, even before any significant changes in Arctic sea ice occur. Only on longer timescales (beyond the first few months) does the decrease in sea ice become an important contributor to AA via the albedo feedback and increased ocean-to-atmosphere heat flux. An important limitation of our CMIP5 analysis is that internal climate variability is large on the short time scales considered. To overcome this limitation &amp;#8211; and thus better isolate the GHG-forced response &amp;#8211; we produced a large ensemble (100 members) of instantaneous CO&lt;sub&gt;2&lt;/sub&gt;-quadrupling simulations using a single GCM, the NCAR Community Earth System Model (CESM1). In our new CESM1 ensemble we find the same rapid AA response seen in the CMIP5 models, confirming that AA ultimately owes its existence to fast atmospheric processes.&lt;/p&gt;

scholarly journals The emergence of surface-based Arctic amplification

2008 ◽  
Vol 2 (4) ◽  
pp. 601-622 ◽  
Author(s):  
M. C. Serreze ◽  
A. P. Barrett ◽  
J. C. Stroeve ◽  
D. N. Kindig ◽  
M. M. Holland
Keyword(s):  
Sea Ice ◽  
21St Century ◽  
Lower Troposphere ◽  
Cold Season ◽  
The Arctic ◽  
Arctic Amplification ◽  
Sea Ice Extent ◽  
Air Temperatures ◽  
The Arctic Ocean ◽  
Heat Transfers

Abstract. Rises in surface and lower troposphere air temperatures through the 21st century are projected to be especially pronounced over the Arctic Ocean during the cold season. This Arctic amplification is largely driven by loss of the sea ice cover, allowing for strong heat transfers from the ocean to the atmosphere. Consistent with observed reductions in sea ice extent, fields from the NCEP/NCAR reanalysis suggest emergence of surface-based Arctic amplification in the last decade.

Mean climatic characteristics in high northern latitudes in an ocean-sea ice-atmosphere coupled model

2004 ◽  
Vol 21 (2) ◽  
pp. 236-244 ◽  
Author(s):  
Xiying Liu ◽  
Xuehong Zhang ◽  
Yongqiang Yu ◽  
Rucong Yu
Keyword(s):  
Sea Ice ◽  
Coupled Model ◽  
Northern Latitudes ◽  
Climatic Characteristics

scholarly journals Utilizing Earth Observations of Soil Freeze/Thaw Data and Atmospheric Concentrations to Estimate Cold Season Methane Emissions in the Northern High Latitudes

2021 ◽  
Vol 13 (24) ◽  
pp. 5059
Author(s):  
Maria Tenkanen ◽  
Aki Tsuruta ◽  
Kimmo Rautiainen ◽  
Vilma Kangasaho ◽  
Raymond Ellul ◽  
...  
Keyword(s):  
A Priori Estimates ◽  
A Priori ◽  
Cold Season ◽  
Methane Emissions ◽  
Anthropogenic Emissions ◽  
High Latitudes ◽  
Freeze Thaw ◽  
Northern Latitudes ◽  
Priori Estimates ◽  
Methane Fluxes

The northern wetland methane emission estimates have large uncertainties. Inversion models are a qualified method to estimate the methane fluxes and emissions in northern latitudes but when atmospheric observations are sparse, the models are only as good as their a priori estimates. Thus, improving a priori estimates is a competent way to reduce uncertainties and enhance emission estimates in the sparsely sampled regions. Here, we use a novel way to integrate remote sensing soil freeze/thaw (F/T) status from SMOS satellite to better capture the seasonality of methane emissions in the northern high latitude. The SMOS F/T data provide daily information of soil freezing state in the northern latitudes, and in this study, the data is used to define the cold season in the high latitudes and, thus, improve our knowledge of the seasonal cycle of biospheric methane fluxes. The SMOS F/T data is implemented to LPX-Bern DYPTOP model estimates and the modified fluxes are used as a biospheric a priori in the inversion model CarbonTracker Europe-CH4. The implementation of the SMOS F/T soil state is shown to be beneficial in improving the inversion model’s cold season biospheric flux estimates. Our results show that cold season biospheric CH4 emissions in northern high latitudes are approximately 0.60 Tg lower than previously estimated, which corresponds to 17% reduction in the cold season biospheric emissions. This reduction is partly compensated by increased anthropogenic emissions in the same area (0.23 Tg), and the results also indicates that the anthropogenic emissions could have even larger contribution in cold season than estimated here.

scholarly journals Salinity effects on cultured Neogloboquadrina pachyderma (sinistral) from high latitudes: new paleoenvironmental insights

2021 ◽  
Vol 41 (1) ◽  
Author(s):  
Jacqueline Bertlich ◽  
Nikolaus Gussone ◽  
Jasper Berndt ◽  
Heinrich F. Arlinghaus ◽  
Gerhard S. Dieckmann
Keyword(s):  
Sea Ice ◽  
Cold Water ◽  
Weddell Sea ◽  
Wall Thickening ◽  
High Latitudes ◽  
Neogloboquadrina Pachyderma ◽  
Antarctic Sea Ice ◽  
The Antarctic ◽  
Water Species ◽  
Cold Water Species

AbstractThis study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.

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