scholarly journals Dipole Pattern of Meridional Atmospheric Internal Energy Transport Across the Arctic Gate

2021 ◽  
Author(s):  
Mikhail M. Latonin ◽  
Leonid P. Bobylev ◽  
Igor L. Bashmachnikov ◽  
Richard Davy
Keyword(s):  
Heat Transport ◽  
Internal Energy ◽  
Latent Heat ◽  
Energy Transport ◽  
Regional Analysis ◽  
Empirical Orthogonal Functions ◽  
Western Hemisphere ◽  
The Arctic ◽  
Eastern Hemisphere ◽  
Dipole Pattern

Abstract High-latitude atmospheric meridional energy transport plays a fundamental role in the Arctic climate system. However, despite numerous studies, there are no established clear regional features of the atmospheric energy transport components from a large-scale perspective. This study aims at investigating the internal energy and its instantaneous sensible and latent heat transports in the troposphere through the Arctic gate at 70°N using the high-resolution climate reanalysis ERA5. We have done a regional analysis of the time series of heat fluxes across the zonal section and found by decomposing them into the empirical orthogonal functions that they have opposing features for the Eastern and Western Hemispheres. In particular, the sensible heat transport dominates in the Western Hemisphere, whereas the latent heat transport dominates in the Eastern Hemisphere. Moreover, we detected the existence of an anti-phase dipole pattern for each of these components in the entire troposphere, which is robust because it was retained during both the climate cooling in 1950–1978 and warming in 1979–2019. The hemispheric net fluxes indicate that the Arctic gains internal energy mostly due to the latent heat transport.

The effect of latent heat transport by waves on Greenland Surface Mass Balance

2020 ◽  
Author(s):  
Tuomas Ilkka Henrikki Heiskanen ◽  
Rune Grand Graversen
Keyword(s):  
Mass Balance ◽  
Heat Transport ◽  
Latent Heat ◽  
Energy Transport ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Circulation Patterns

<p>The Arctic region shows some of the world's most significant signs of climate change. The atmospheric energy transport plays an important role for the Arctic climate; the atmospheric transport contributes an amount of energy into the Arctic that is comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static energy transport and the synoptic scale component of the latent heat transport. </p><p>A large concern for humanity is that the climate change in polar regions will lead to significant melting of the ice sheets and glaciers. In fact the discharge water from the Greenland ice sheet has recently increased to the extent that this ice sheet is one of the major contributorsto sea-level rise. Here we test the hypothesis that the recent rapid increase in melt of the Greenland ice sheet is linked to a shift of planetary-scale waves transporting warm and humid air over the ice sheet.</p><p>The effect of the atmospheric energy transport is investigated by correlating the divergence of energy over the Greenland ice sheet with the surface mass balance of this ice sheet. The divergence of latent heat transport is found to correlate positively with the surface mass balance along the edges of the ice sheet, and negatively in the interior. This indicates that a convergence of latent at the edges of the ice sheet lead to a increased mass discharge from the ice sheet, whilst in the interior converging latent heat indicates an accumulation of mass to the ice sheet. </p><p>To investigate the effect of transport by planetary and synoptic scale waves on the Greenland ice sheet surface mass balance the mass flux component of the transport divergence is decomposed into wavenumbers through the application of a Fourier series. The divergences of transport contributions of each wavenumber are then correlated with the surface mass balance of the Greenland ice sheet. The correlations between the surface-mass balance and divergence of transport contributions by different wavenumbers reveals the relative impact of atmospheric circulation systems, such as Rossby waves and cyclones, on the Greenland ice sheet mass balance. Further, identifying shifts in the circulation patterns over Greenland by applying self organizing maps, or similar methods, and investigations of how these circulation patterns affect the energy transport over Greenland by atmospheric waves of different scales are also pursued.<br> <br>  </p>

scholarly journals Influence of the Arctic Circumpolar Vortex on the Mass Balance of Canadian High Arctic Glaciers

2007 ◽  
Vol 20 (18) ◽  
pp. 4586-4598 ◽  
Author(s):  
Alex S. Gardner ◽  
Martin Sharp
Keyword(s):  
Mass Balance ◽  
Regime Shift ◽  
High Arctic ◽  
Western Hemisphere ◽  
The Arctic ◽  
Glacier Mass Balance ◽  
Canadian High Arctic ◽  
Circumpolar Vortex ◽  
Eastern Hemisphere ◽  
Air Temperatures

Abstract Variability in July mean surface air temperatures from 1963 to 2003 accounted for 62% of the variance in the regional annual glacier mass balance signal for the Canadian High Arctic. A regime shift to more negative regional glacier mass balance occurred between 1986 and 1987, and is linked to a coincident shift from lower to higher mean July air temperatures. Both the interannual changes and the regime shifts in regional glacier mass balance and July air temperatures are related to variations in the position and strength of the July circumpolar vortex. In years when the July vortex is “strong” and its center is located in the Western Hemisphere, positive mass balance anomalies prevail. In contrast, highly negative mass balance anomalies occur when the July circumpolar vortex is either weak or strong without elongation over the Canadian High Arctic, and its center is located in the Eastern Hemisphere. The occurrence of westerly positioned July vortices has decreased by 40% since 1987. The associated shift to a dominantly easterly positioned July vortex was associated with an increased frequency of tropospheric ridging over the Canadian High Arctic, higher surface air temperatures, and more negative regional glacier mass balance.

scholarly journals Dynamical and chemical processes contributing to ozone loss in exceptional Arctic stratosphere winter-spring of 2020

2021 ◽  
Author(s):  
Sergei P. Smyshlyaev ◽  
Pavel N. Vargin ◽  
Alexander N. Lukyanov ◽  
Natalia D. Tsvetkova ◽  
Maxim A. Motsakov
Keyword(s):  
Polar Vortex ◽  
Reanalysis Data ◽  
Chemical Processes ◽  
Western Hemisphere ◽  
The Arctic ◽  
Spring Season ◽  
Dynamical Processes ◽  
Stratospheric Polar Vortex ◽  
Ozone Loss ◽  
Eastern Hemisphere

Abstract. The features of dynamical processes and changes in the ozone layer in the Arctic stratosphere during the winter-spring season 2019–2020 are analyzed using ozonesondes, reanalysis data and numerical experiments with a chemistry-transport model (CTM). Using the trajectory model of the Central Aerological Observatory (TRACAO) and the ERA5 reanalysis ozone mixing ratio data, a comparative analysis of the evolution of stratospheric ozone averaged along the trajectories in the winter-spring seasons of 2010–2011, 2015–2016, and 2019–2020 was carried out, which demonstrated that the largest ozone loss at altitudes of 18–20 km within stratospheric polar vortex in the Arctic in winter-spring 2019–2020 exceeded the corresponding values of the other two winter-spring seasons 2010–2011 and 2015–2016 with the largest decrease in ozone content in recent year. The total decrease in the column ozone inside the stratospheric polar vortex, calculated using the vertical ozone profiles obtained based on the ozonesondes data, in the 2019–2020 winter-spring season was more than 150 Dobson Units, which repeated the record depletion for the 2010–2011 winter-spring season. At the same time, the maximum ozone loss in winter 2019–2020 was observed at lower levels than in 2010–2011, which is consistent with the results of trajectory analysis and the results of other authors. The results of numerical calculations with the CTM with dynamical parameters specified from the MERRA-2 reanalysis data, carried out according to several scenarios of accounting for the chemical destruction of ozone, indicated that both dynamical and chemical processes make contributions to ozone loss inside the polar vortex. In this case, dynamical processes predominate in the western hemisphere, while in the eastern hemisphere chemical processes make an almost equal contribution with dynamical factors, and the chemical depletion of ozone is determined not only by heterogeneous processes on the surface of the polar stratospheric clouds, but by the gas-phase destruction in nitrogen catalytic cycles as well.

A multimodel investigation of atmospheric mechanisms for driving Arctic amplification in warmer climates

2021 ◽  
pp. 1-55
Author(s):  
Deepashree Dutta ◽  
Steven C. Sherwood ◽  
Katrin J. Meissner ◽  
Alex Sen Gupta ◽  
Daniel J. Lunt ◽  
...  
Keyword(s):  
Heat Transport ◽  
General Circulation ◽  
Energy Transport ◽  
Longwave Radiation ◽  
General Circulation Models ◽  
The Arctic ◽  
Arctic Warming ◽  
Surface Warming ◽  
Poleward Heat Transport ◽  
Warm Climates

AbstractWhen simulating past warm climates, such as the early Cretaceous and Paleogene periods, general circulation models (GCMs) underestimate the magnitude of warming in the Arctic. Additionally, model intercomparisons show a large spread in the magnitude of Arctic warming for these warmer-than-modern climates. Several mechanisms have been proposed to explain these disagreements, including the unrealistic representation of polar clouds or underestimated poleward heat transport in the models. This study provides an intercomparison of Arctic cloud and atmospheric heat transport (AHT) responses to strong imposed polar-amplified surface ocean warming across four atmosphere-only GCMs. All models simulate an increase in high clouds throughout the year; the resulting reduction in longwave radiation loss to space acts to support the imposed Arctic warming. The response of low and mid-level clouds varies considerably across the models, with models responding differently to surface warming and sea ice removal. The AHT is consistently weaker in the imposed warming experiments due to a large reduction in dry static energy transport that offsets a smaller increase in latent heat transport, thereby opposing the imposed surface warming. Our idealised polar amplification experiments require very large increases in implied ocean heat transport (OHT) to maintain steady state. Increased CO2 or tropical temperatures that likely characterised past warm climates, reduces the need for such large OHT increases.

scholarly journals Synthesis and evaluation of historical meridional heat transport from midlatitudes towards the Arctic

2020 ◽  
Vol 11 (1) ◽  
pp. 77-96
Author(s):  
Yang Liu ◽  
Jisk Attema ◽  
Ben Moat ◽  
Wilco Hazeleger
Keyword(s):  
Climate Variability ◽  
Heat Transport ◽  
Climate Models ◽  
Energy Transport ◽  
Reanalysis Data ◽  
Arctic Climate ◽  
The Arctic ◽  
Global Ocean ◽  
Data Sets ◽  
Sea Ice Concentration

Abstract. Meridional energy transport (MET), both in the atmosphere (AMET) and ocean (OMET), has significant impact on the climate in the Arctic. In this study, we quantify AMET and OMET at subpolar latitudes from six reanalysis data sets. We investigate the differences between the data sets and we check the coherence between MET and the Arctic climate variability at interannual timescales. The results indicate that, although the mean transport in all data sets agrees well, the spatial distributions and temporal variations of AMET and OMET differ substantially among the reanalysis data sets. For the ocean, only after 2007, the low-frequency signals in all reanalysis products agree well. A further comparison with observed heat transport at 26.5∘ N and the subpolar Atlantic, and a high-resolution ocean model hindcast confirms that the OMET estimated from the reanalysis data sets are consistent with the observations. For the atmosphere, the differences between ERA-Interim and the Japanese 55-year Reanalysis (JRA-55) are small, while the Modern-Era Retrospective analysis for Research and Applications version 2 (MERRA-2) differs from them. An extended analysis of linkages between Arctic climate variability and AMET shows that atmospheric reanalyses differ substantially from each other. Among the chosen atmospheric products, ERA-Interim and JRA-55 results are most consistent with those from coupled climate models. For the ocean, the Ocean Reanalysis System 4 (ORAS4) and Simple Ocean Data Assimilation version 3 (SODA3) agree well on the relation between OMET and sea ice concentration (SIC), while the GLobal Ocean reanalyses and Simulations version 3 (GLORYS2V3) deviates from those data sets. The regressions of multiple fields in the Arctic on both AMET and OMET suggest that the Arctic climate is sensitive to changes of meridional energy transport at subpolar latitudes in winter. Given the good agreement on the diagnostics among assessed reanalysis products, our study suggests that the reanalysis products are useful for the evaluation of energy transport. However, assessments of products with the AMET and OMET estimated from reanalysis data sets beyond interannual timescales should be conducted with great care and the robustness of results should be evaluated through intercomparison, especially when studying variability and interactions between the Arctic and midlatitudes.

The effect of a shift in the atmospheric energy transport scales on the Greenland ice sheet surface mass balance

2021 ◽  
Author(s):  
Tuomas Ilkka Henrikki Heiskanen
Keyword(s):  
Mass Balance ◽  
Heat Transport ◽  
Latent Heat ◽  
Energy Transport ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Synoptic Scale ◽  
The South ◽  
Surface Mass

<p> Climate change in the Arctic is likely to lead to a significant melting of ice sheets and glaciers. This will be an important driving<br>  mechanism for future sea-level rise. During the last decades the Greenland ice sheet has lost mass at an unprecedented rate. <br>  This has lead to the Greenland ice sheet to be an important contributor to sea-level rise. Here we test the hypothesis that a <br>  change in the atmospheric circulation over Greenland contributes to the exceptionally negative surface mass balance observed over the<br>  last decades. </p><p>  The atmospheric transport contributes an amount of energy into the Arctic that is <br>  comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that <br>  the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static <br>  energy transport and the synoptic scale component of the latent heat transport. </p><p>  The south west ablation zone of the Greenland ice-sheet is one of the main contributors to mass loss of the ice-sheet. Comparing <br>  the ablation in this area with patterns of the divergence of latent heat transport shows that similar decadal-scale trends are found <br>  in the surface mass balance and divergence of latent heat transport data. <br>  During the last decades the divergence of latent heat has shifted from <br>  synoptic scale to planetary scale, implying an increased convergence of latent heat transport by synoptic scale waves to the south<br>  west coast of Greenland. </p><p>  Through linear regressions we find that the shift from planetary scale transport convergence to synoptic scale convergence describes<br>  approximately 25 % of the surface mass balance anomaly, since year 2000, in the south west region of Greenland. The total amount <br>  of energy transported into this region has not changed dramatically. Hence this indicates the importance of the systems transporting <br>  the energy or conditions under which the transport by the different wave types take place. <br>  Transport by synoptic scale waves seems to be an important contributor to the surface mass loss of the Greenland ice<br>  sheet. A possible explanation for this is that synoptic scale transport into the ablation zone is associated with warmer conditions<br>  than the planetary component over the same region. Hence providing favorable conditions for ice melting, and possibly a larger <br>  fraction of liquid precipitation. However, why this is so is still a subject we study. <br>  Further we try to identify how different melt driving mechanisms are <br>  associated with both planetary and synoptic scale divergence of energy transport, and which of these lead to the differing effects on<br>  the surface mass balance of the Greenland ice sheet.</p>

scholarly journals Numerical Modeling of Ozone Loss in the Exceptional Arctic Stratosphere Winter–Spring of 2020

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1470
Author(s):  
Sergey P. Smyshlyaev ◽  
Pavel N. Vargin ◽  
Maksim A. Motsakov
Keyword(s):  
Numerical Experiments ◽  
Reanalysis Data ◽  
Wave Activity ◽  
Western Hemisphere ◽  
The Arctic ◽  
Polar Stratospheric Clouds ◽  
Stratospheric Polar Vortex ◽  
Eastern Hemisphere ◽  
Stratospheric Clouds ◽  
Catalytic Cycles

Dynamical processes and changes in the ozone layer in the Arctic stratosphere during the winter of 2019–2020 were analyzed using numerical experiments with a chemistry-transport model (CTM) and reanalysis data. The results of numerical calculations using CTM with Dynamic parameters specified from the Modern Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis data, carried out according to several scenarios of accounting for the chemical destruction of ozone, demonstrated that both Dynamic and chemical processes contribute significantly to ozone changes over the selected World Ozone and Ultraviolet Radiation Data Centre network stations, both in the Eastern and in the Western hemispheres. Based on numerical experiments with the CTM, the specific Dynamic conditions of winter–spring 2019–2020 described a decrease in ozone up to 100 Dobson Units (DU) in the Eastern Hemisphere and over 150 DU in the Western Hemisphere. In this case, the photochemical destruction of ozone in both the Western and Eastern Hemispheres at a maximum was about 50 DU with peaks in April in the Eastern Hemisphere and in March and April in the Western Hemisphere. Heterogeneous activation of halogen gases on the surface of polar stratospheric clouds, on the one hand, led to a sharp increase in the destruction of ozone in chlorine and bromine catalytic cycles, and, on the other hand, decreased its destruction in nitrogen catalytic cycles. Analysis of wave activity using 3D Plumb fluxes showed that the enhancement of upward wave activity propagation in the middle of March over the Gulf of Alaska was observed during the development stage of the minor sudden stratospheric warming (SSW) event that led to displacement of the stratospheric polar vortex to the north of Canada and decrease of polar stratospheric clouds’ volume.

The seesaw response of the Intertropical and South Pacific convergence zones to hemispherically asymmetric thermal forcing

2020 ◽  
Author(s):  
Bowen Zhao ◽  
Alexey Fedorov
Keyword(s):  
Heat Transport ◽  
Energy Transport ◽  
Convergence Zone ◽  
Ocean Heat Transport ◽  
Tropical Precipitation ◽  
Latitudinal Position ◽  
Dipole Pattern ◽  
Slab Ocean ◽  
Fully Coupled ◽  
The Tropical Pacific

<p>Arguments based on atmospheric energetics and aqua-planet model simulations link the latitudinal position of the Intertropical Convergence Zone (ITCZ) to atmospheric cross-equatorial energy transport –- a greater southward transport corresponds to a more northerly position of the ITCZ. This idea is often invoked to explain an interhemispheric dipole pattern of precipitation anomalies in paleoclimates. In contrast, here we demonstrate that in the tropical Pacific the response of the fully coupled ocean-atmosphere system to a hemispherically asymmetric thermal  forcing, modulating this energy transport, involves an interplay between the ITCZ and its counterpart in the South Pacific - the Southern Pacific Convergence Zone (SPCZ). This interplay leads to interhemispheric seesaw changes in tropical precipitation, such that the latitudinal position of each rain band remains largely fixed, but their intensities follow a robust inverse relationship. The seesaw behavior is also evident in the past and future coupled climate simulations of the Climate Model Intercomparison Project Phase 5 (CMIP5). We also show that the tropical Pacific precipitation response to thermal forcing is qualitatively different between the aqua-planet (without ocean heat transport), slab-ocean (with climatological ocean heat transport represented by a ``Q-flux'') and fully-coupled model configurations. Specifically, the induced changes in the ITCZ latitudinal position successively decrease, while the seesaw precipitation intensity response becomes more prominent, from the aqua-planet to the slab-ocean to the fully-coupled configuration. Thus, the ITCZ/SPCZ seesaw can explain the paleoclimate precipitation dipole pattern without invoking a too strong climate forcing and is relevant to future projections of tropical precipitation.</p>

Morphological types of spermatheca in Coreidae: bearing on intra-familial classification and tribal-groupings (Hemiptera: Heteroptera)

Zootaxa ◽  
2020 ◽  
Vol 4834 (4) ◽  
pp. 451-501
Author(s):  
DOMINIQUE PLUOT-SIGWALT ◽  
PIERRE MOULET
Keyword(s):  
Western Hemisphere ◽  
Type I ◽  
Type Ii ◽  
Type Iii ◽  
Spermathecal Duct ◽  
Eastern Hemisphere ◽  
Intermediate Part ◽  
Muscular Pump ◽  
Familial Classification

The morphology of the spermatheca is described in 109 species of 86 genera representing all four currently recognised subfamilies of Coreidae, covering the undivided Hydarinae, both tribes of Pseudophloeinae, all three tribes of Meropachyinae and 27 of the 32 tribes of Coreinae. Three types of spermatheca are recognised. Type I is bipartite, consisting only of a simple tube differentiated into distal seminal receptacle and proximal spermathecal duct and lacks the intermediate part present in most Pentatomomorpha, in which it serves as muscular pump. Type II is also bipartite but more elaborate in form with the receptacle generally distinctly wider than the duct. Type III is tripartite, with receptacle, duct and an often complex intermediate part. Four subtypes are recognised within type III. Type I is found only in Hydarinae and type II only in Pseudophloeinae. Type III is found in both Coreinae and Meropachyinae. Subtype IIIA (“Coreus-group”) unites many tribes from the Eastern Hemisphere and only one (Spartocerini) from the Western Hemisphere. Subtypes IIIB (“Nematopus-group”) and IIID (“Anisoscelis-group”) are confined to taxa from the Western Hemisphere and subtype IIIC (“Chariesterus-group”) is found in tribes from both hemispheres. The polarity of several characters of the intermediate part and some of the spermathecal duct is evaluated, suggesting autapomorphies or apomorphies potentially relevant to the classification of Coreidae at the sufamilial and tribal levels. Characters of the intermediate part strongly indicate that the separation of Meropachyinae and Coreinae as currently constituted cannot be substantiated. The tribes Anisoscelini, Colpurini, Daladerini and Hyselonotini are heterogeneous, each exhibiting two subtypes of spermatheca, and probably polyphyletic. Two tribes, Cloresmini and Colpurini, requiring further investigation remain unplaced. This study demonstrates the great importance of characters of the spermatheca, in particular its intermediate part, for research into the phylogeny and taxonomy of Pentatomomorpha. 

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