Arctic Lower-Tropospheric Warm and Cold Extremes: Horizontal and Vertical Transport, Diabatic Processes, and Linkage to Synoptic Circulation Features

2020 ◽  
Vol 33 (3) ◽  
pp. 993-1016 ◽  
Author(s):  
Lukas Papritz
Keyword(s):  
North Atlantic ◽  
Temperature Anomaly ◽  
Storm Track ◽  
High Arctic ◽  
The Arctic ◽  
Air Masses ◽  
The North ◽  
Diabatic Processes ◽  
Synoptic Circulation ◽  
Cold Extremes

AbstractThe thermodynamic processes and synoptic circulation features driving lower-tropospheric temperature extremes in the high Arctic (>80°N) are investigated. Based on 10-day kinematic backward trajectories from the 5% most intense potential temperature anomalies, the contributions of horizontal and vertical transport, subsidence-induced warming, and diabatic processes to the generation of the Arctic temperature anomaly are quantified. Cold extremes are mainly the result of sustained radiative cooling due to a sheltering of the Arctic from meridional airmass exchanges. This is linked to a strengthening of the tropospheric polar vortex, a reduced frequency of high-latitude blocking, and in winter also a southward shift of the North Atlantic storm track. The temperature anomaly of 60% of wintertime extremely warm air masses (90% in summer) is due to transport from a potentially warmer region. Subsidence from the Arctic midtroposphere in blocking anticyclones is the most important warming process with the largest contribution in summer (70% of extremely warm air masses). In both seasons, poleward transport of already warm air masses contributes around 20% and is favored by a poleward shift of the North Atlantic storm track. Finally, about 40% of the air masses in winter are of an Arctic origin and experience diabatic heating by surface heat fluxes in marine cold air outbreaks. Our study emphasizes the importance of processes in the Arctic and the relevance of anomalous blocking—in winter in the Barents, Kara, and Laptev Seas and in summer in the high Arctic—for the formation of warm extremes.

Dynamic and thermodynamic drivers of Arctic lower tropospheric warm extremes

2020 ◽  
Author(s):  
Lukas Papritz
Keyword(s):  
Storm Track ◽  
Lower Troposphere ◽  
High Arctic ◽  
Heat Fluxes ◽  
The Arctic ◽  
Sensible Heat ◽  
Humid Air ◽  
Secondary Importance ◽  
Air Masses ◽  
Diabatic Processes

<p align="justify">Recent decades have revealed dramatic changes in the high Arctic (> 80°N) related to natural variability and anthropogenic climate change. In particular, episodes of extremely warm temperatures in the lower troposphere and their role for sea ice melting have gained considerable attention. While it has been recognized that injections of warm and humid air masses contribute to wintertime warm anomalies, summertime warm anomalies have also been linked to blocking anticyclones within the high Arctic. Yet, the relative importance of the various thermodynamic and atmospheric dynamical processes that can contribute to the formation of extreme warm anomalies in the high Arctic is poorly understood.</p><p align="justify">In this work, we present a systematic analysis of the processes leading to the formation of winter- and summertime lower tropospheric warm extremes in the high Arctic by means of kinematic backward trajectories based on the ERA-Interim reanalysis. The trajectories enable us to quantify the relative contributions of poleward transport from (potentially) warmer regions, adiabatic warming due to subsidence, and diabatic heating associated with surface sensible heat fluxes and latent heat release. Furthermore, we relate these processes to atmospheric dynamical flow features such as atmospheric blocking and extratropical cyclones.</p><p align="justify">Our analyses reveal that subsidence in blocking anticyclones over the Barents and Kara Seas and diabatic warming by surface sensible heat fluxes are the dominant mechanisms leading to wintertime warm extremes (contributing about 40% each), whereas the transport from southerly latitudes – predominantly accomplished by the injection of warm and humid air masses associated with an intensified and westward displaced storm track in the Nordic Seas - is of secondary importance (20%). Summertime warm anomalies, in contrast, are essentially the result of subsidence in blocking anticyclones (70%) that are located within the high Arctic. Thus, our findings point towards a rich, seasonally varying spectrum of dynamical and thermodynamic processes contributing to Arctic warm extremes that result from a complex interplay between transport induced by dynamical weather systems and diabatic processes. Furthermore, they emphasize the importance of processes within the Arctic for the formation of warm extremes.</p><p align="justify">Papritz, L., 2019: Arctic lower tropospheric warm and cold extremes: horizontal and vertical transport, diabatic processes, and linkage to synoptic circulation features, <em>J. Climate</em>, doi: 10.1175/JCLI-D-19-0638.1</p>

scholarly journals Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

2010 ◽  
Vol 10 (21) ◽  
pp. 10223-10236 ◽  
Author(s):  
J. B. Gilman ◽  
J. F. Burkhart ◽  
B. M. Lerner ◽  
E. J. Williams ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Transport Model ◽  
Arctic Basin ◽  
The Arctic ◽  
Arctic Boundary Layer ◽  
Air Masses ◽  
The North ◽  
The North Atlantic

Abstract. The influence of halogen oxidation on the variabilities of ozone (O3) and volatile organic compounds (VOCs) within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N) was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI), multi-year ice (MYI), and total ICE (FYI+MYI). O3 anti-correlated with the modeled total ICE tracer (r = −0.86) indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

scholarly journals The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength

2004 ◽  
Vol 4 (5) ◽  
pp. 6127-6148 ◽  
Author(s):  
K. Walter ◽  
H.-F. Graf
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Polar Vortex ◽  
The State ◽  
Storm Tracks ◽  
The Arctic ◽  
Ample Evidence ◽  
Vortex Strength ◽  
The North ◽  
The North Atlantic

Abstract. There is ample evidence that the state of the northern polar stratospheric vortex in boreal winter influences tropospheric variability. Therefore, the main teleconnection patterns over the North Atlantic are defined separately for winter episodes in which the zonal mean wind at 50 hPa and 65° N is above or below the critical Rossby velocity for zonal planetary wave one. It turns out that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the "polar vortex is strong", there exists "one" meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the "polar vortex is weak", there exist "two" such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results show that it is essential to include the state of the upper dynamic boundary conditions (the polar vortex strength) in any study of the variability over the North Atlantic. Climate forecast based solely on the forecast of a "classic NAO" and further statistical downscaling may lead to the wrong conclusions if the state of the polar vortex is not considered as well.

scholarly journals The influence of Arctic air masses on climatic conditions of the snow accumulation period in the center of the European territory of Russia

2021 ◽  
pp. 16-25
Author(s):  
Julia Nikolaevna Chizhova
Keyword(s):  
North Atlantic ◽  
Arctic Oscillation ◽  
Winter Precipitation ◽  
Climatic Conditions ◽  
The Arctic ◽  
Air Masses ◽  
The North ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation ◽  
The Relationship

The subject of this article is exmination of the influence of the Arctic air flow on the climatic conditions of the winter period in the center of the European territory of Russia (Moscow). In recent years, the question of the relationship between regional climatic conditions and such global circulation patterns as the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AK) has become increasingly important. Based on the data of long-term observations of temperature and precipitation, the relationship with the AK and NAO was considered. For the winter months of the period 2014-2018, the back trajectories of the movement of air masses were computed for each date of precipitation to identify the sources of precipitation. The amount of winter precipitation that forms the snow cover of Moscow has no connection with either the North Atlantic Oscillation or the Arctic Oscillation. The Moscow region is located at the intersection of the zones of influence of positive and negative phases of both cyclonic patterns (AK and NAO), which determine the weather in the Northern Hemisphere. For the winter months, a correlation between the surface air temperature and NAO (r = 0.72) and AK (r = 0.66) was established. Winter precipitation in the center of the European territory of Russiais mainly associated with the unloading of Atlantic air masses. Arctic air masses relatively rarely invade Moscow region and bring little precipitation (their contribution does not exceed 12% of the total winter precipitation).

scholarly journals The North Atlantic variability structure, storm tracks, and precipitation depending on the polar vortex strength

2005 ◽  
Vol 5 (1) ◽  
pp. 239-248 ◽  
Author(s):  
K. Walter ◽  
H.-F. Graf
Keyword(s):  
North Atlantic ◽  
Storm Track ◽  
Polar Vortex ◽  
The State ◽  
Storm Tracks ◽  
The Arctic ◽  
Boreal Winter ◽  
Vortex Strength ◽  
The North ◽  
The North Atlantic

Abstract. Motivated by the strong evidence that the state of the northern hemisphere vortex in boreal winter influences tropospheric variability, teleconnection patterns over the North Atlantic are defined separately for winter episodes where the zonal wind at 50hPa and 65° N is above or below the critical velocity for vertical propagation of zonal planetary wave 1. We argue that the teleconnection structure in the middle and upper troposphere differs considerably between the two regimes of the polar vortex, while this is not the case at sea level. If the polar vortex is strong, there exists one meridional dipole structure of geopotential height in the upper and middle troposphere, which is situated in the central North Atlantic. If the polar vortex is weak, there exist two such dipoles, one over the western and one over the eastern North Atlantic. Storm tracks (and precipitation related with these) are determined by mid and upper tropospheric conditions and we find significant differences of these parameters between the stratospheric regimes. For the strong polar vortex regime, in case of a negative upper tropospheric "NAO" index we find a blocking height situation over the Northeast Atlantic and the strongest storm track of all. It is reaching far north into the Arctic Ocean and has a secondary maximum over the Denmark Strait. Such storm track is not found in composites based on a classic NAO defined by surface pressure differences between the Icelandic Low and the Azores High. Our results suggest that it is important to include the state of the polar vortex strength in any study of the variability over the North Atlantic.

scholarly journals Black carbon in the marine boundary layer over the North Atlantic and seas of the Russian arctic in june-september 2017

2019 ◽  
Vol 59 (5) ◽  
pp. 771-776
Author(s):  
V. P. Shevchenko ◽  
V. M. Kopeikin ◽  
A. N. Novigatsky ◽  
G. V. Malafeev
Keyword(s):  
Boundary Layer ◽  
Black Carbon ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
The Arctic ◽  
Air Masses ◽  
South Eastern ◽  
The North ◽  
The North Atlantic ◽  
Eastern Baltic

The paper presents the results of a study of the concentrations of black carbon in the marine boundary layer over the Baltic and North Seas, the North Atlantic, the Norwegian, the Barents, the Kara and the Laptev seas from June 30 to September 29, 2017 in the 68th and 69th voyages of research vessel "Akademik Mstislav Keldysh". Black carbon has a significant impact on climate change and the degree of pollution of the Arctic. Black carbon is formed as a result of incomplete combustion of fossil fuels (primarily coal, oil) and biomass or biofuel. It consists of submicron particles and their aggregates and can be transported a great distance from the source. Samples were taken by pumping air for 46 hours through quartz filters Hahnemule at an altitude of 10 m above sea level in a headwind to prevent smoke of the vessel from entering the filters. Subsequently, the black carbon content was determined in the laboratory by the aetalometric method. The backward trajectories of the air mass transfer and the black carbon particles transported by them to the sampling points were calculated using the HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) model at http://www.arl.noaa.gov/ready.html. The conducted studies show low values of black carbon concentrations (50 ng/m3) along the expedition route when air masses came from the background areas of the North Atlantic and the Arctic. High concentrations of black carbon (100200 ng/m3 and higher) are characteristic for areas with active navigation (the South-Eastern Baltic, the North Sea) and near ports (eg Reykjavik), as well as for incoming air masses from the industrialized regions of Europe to South-Eastern Baltic and from areas of oil and gas fields where associated gas is flared (the North, the Norwegian and the Kara seas).

scholarly journals Atmospheric mercury speciation dynamics at the high-altitude Pic du Midi Observatory, southern France

2016 ◽  
Author(s):  
X. W. Fu ◽  
N. Marusczak ◽  
L. -E. Heimbürger ◽  
B. Sauvage ◽  
F. Gheusi ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Arctic Region ◽  
The Arctic ◽  
Free Troposphere ◽  
Air Masses ◽  
Upper Troposphere ◽  
The North

Abstract. Continuous measurements of atmospheric gaseous elemental mercury (GEM), particulate bound mercury (PBM) and gaseous oxidized mercury (GOM) at the high-altitude Pic du Midi Observatory (PDM, 2877 m a.s.l) in southern France were made from Nov 2011 to Nov 2012. The mean GEM, PBM and GOM concentrations were 1.86 ng m−3, 14 pg m−3 and 27 pg m−3, respectively and we observed 44 high PBM (up to 98 pg m−3) and 61 high GOM (up to 295 pg m−3) events. The high PBM events occurred mainly in cold seasons (winter and spring) whereas high GOM events were mainly observed in the warm seasons (summer and autumn). In cold seasons the maximum air mass residence times (ARTs) associated with high PBM events were observed in the upper troposphere over North America. The ratios of high PBM ARTs to total ARTs over North America, Europe, the Arctic region and Atlantic Ocean were all elevated in the cold season compared to the warm season, indicating that the middle and upper free troposphere of the Northern Hemisphere may be more enriched in PBM in cold seasons. PBM concentrations and PBM/GOM ratios during the high PBM events were significantly anti-correlated with atmospheric aerosol concentrations, air temperature and solar radiation, suggesting in situ formation of PBM in the middle and upper troposphere. We identified two distinct types of high GOM events with the GOM concentrations positively and negatively correlated with atmospheric ozone concentrations, respectively. High GOM events positively correlated with ozone were mainly related to air masses from the upper troposphere over the Arctic region and middle troposphere over the temperate North Atlantic Ocean, whereas high GOM events anti-correlated with ozone were mainly related to air masses from the lower free troposphere over the subtropical North Atlantic Ocean. The ARTs analysis demonstrates that the lower and middle free troposphere over the North Atlantic Ocean was the largest source region of atmospheric GOM at PDM Observatory. The ratios of high GOM ARTs to total ARTs over the subtropical North Atlantic Ocean in summer were significantly higher than that over the temperate and sub-arctic North Atlantic Ocean as well as that over the North Atlantic Ocean in other seasons, indicating abundant in situ oxidation of GEM to GOM in the lower free troposphere over the subtropical North Atlantic Ocean in summer.

scholarly journals Arctic Snowfall from CloudSat Observations and Reanalyses

2020 ◽  
Vol 33 (6) ◽  
pp. 2093-2109 ◽  
Author(s):  
L. Edel ◽  
C. Claud ◽  
C. Genthon ◽  
C. Palerme ◽  
N. Wood ◽  
...  
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Hydrological Cycle ◽  
Storm Track ◽  
The Arctic ◽  
Alaska Range ◽  
Weather Forecasts ◽  
Geographical Patterns ◽  
The North

AbstractWhile snowfall makes a major contribution to the hydrological cycle in the Arctic, state-of-the-art climatologies still significantly disagree. We present a satellite-based characterization of snowfall in the Arctic using CloudSat observations, and compare it with various other climatologies. First, we examine the frequency and phase of precipitation as well as the snowfall rates from CloudSat over 2007–10. Frequency of solid precipitation is higher than 70% over the Arctic Ocean and 95% over Greenland, while mixed precipitation occurs mainly over North Atlantic (50%) and liquid precipitation over land south of 70°N (40%). Intense mean snowfall rates are located over Greenland, the Barents Sea, and the Alaska range (>500 mm yr−1), and maxima are located over the southeast coast of Greenland (up to 2000 mm yr−1). Then we compare snowfall rates with the European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis (ERA-Interim, herein ERA-I) and Arctic System Reanalysis (ASR). Similar general geographical patterns are observed in all datasets, such as the high snowfall rates along the North Atlantic storm track. Yet, there are significant mean snowfall rate differences over the Arctic between 58° and 82°N between ERA-I (153 mm yr−1), ASR version 1 (206 mm yr−1), ASR version 2 (174 mm yr−1), and CloudSat (183 mm yr−1). Snowfall rates and differences are larger over Greenland. Phase attribution is likely to be a significant source of snowfall rate differences, especially regarding ERA-I underestimation. In spite of its nadir-viewing limitations, CloudSat is an essential source of information to characterize snowfall in the Arctic.

scholarly journals Atmospheric mercury speciation dynamics at the high-altitude Pic du Midi Observatory, southern France

2016 ◽  
Vol 16 (9) ◽  
pp. 5623-5639 ◽  
Author(s):  
Xuewu Fu ◽  
Nicolas Marusczak ◽  
Lars-Eric Heimbürger ◽  
Bastien Sauvage ◽  
François Gheusi ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Arctic Region ◽  
The Arctic ◽  
Free Troposphere ◽  
Air Masses ◽  
Upper Troposphere ◽  
The North

Abstract. Continuous measurements of atmospheric gaseous elemental mercury (GEM), particulate bound mercury (PBM) and gaseous oxidized mercury (GOM) at the high-altitude Pic du Midi Observatory (PDM Observatory, 2877 m a.s.l.) in southern France were made from November 2011 to November 2012. The mean GEM, PBM and GOM concentrations were 1.86 ng m−3, 14 pg m−3 and 27 pg m−3, respectively and we observed 44 high PBM (peak PBM values of 33–98 pg m−3) and 61 high GOM (peak GOM values of 91–295 pg m−3) events. The high PBM events occurred mainly in cold seasons (winter and spring) whereas high GOM events were mainly observed in the warm seasons (summer and autumn). In cold seasons the maximum air mass residence times (ARTs) associated with high PBM events were observed in the upper troposphere over North America. The ratios of high PBM ARTs to total ARTs over North America, Europe, the Arctic region and Atlantic Ocean were all elevated in the cold season compared to the warm season, indicating that the middle and upper free troposphere of the Northern Hemisphere may be more enriched in PBM in cold seasons. PBM concentrations and PBM ∕ GOM ratios during the high PBM events were significantly anti-correlated with atmospheric aerosol concentrations, air temperature and solar radiation, suggesting in situ formation of PBM in the middle and upper troposphere. We identified two distinct types of high GOM events with the GOM concentrations positively and negatively correlated with atmospheric ozone concentrations, respectively. High GOM events positively correlated with ozone were mainly related to air masses from the upper troposphere over the Arctic region and middle troposphere over the temperate North Atlantic Ocean, whereas high GOM events anti-correlated with ozone were mainly related to air masses from the lower free troposphere over the subtropical North Atlantic Ocean. The ARTs analysis demonstrates that the lower and middle free troposphere over the North Atlantic Ocean was the largest source region of atmospheric GOM at the PDM Observatory. The ratios of high GOM ARTs to total ARTs over the subtropical North Atlantic Ocean in summer were significantly higher than those over the temperate and sub-arctic North Atlantic Ocean as well as that over the North Atlantic Ocean in other seasons, indicating abundant in situ oxidation of GEM to GOM in the lower free troposphere over the subtropical North Atlantic Ocean in summer.

THE POST-GLACIAL COLONIZATION OF THE NORTH ATLANTIC ISLANDS

1988 ◽  
Vol 120 (S144) ◽  
pp. 55-92 ◽  
Author(s):  
J.A. Downes
Keyword(s):  
North America ◽  
North Atlantic ◽  
North American ◽  
High Arctic ◽  
The Arctic ◽  
Land Bridge ◽  
The North ◽  
The North Atlantic ◽  
North Greenland ◽  
Arctic Fauna

AbstractThe paper discusses the nature and origins of the present-day insect faunas of Greenland, Iceland, and the Faeroes in relation to those of North America and Europe. The markedly warm-adapted faunas of the Early Tertiary were modified or eliminated as the climate cooled from the Oligocene onward to the Pleistocene glaciations. The Wisconsinan glaciation peaked about 20 000 years ago, and then gave way rapidly to the arctic and cool temperate climates of the present, and the North Atlantic islands thus became habitable again but separated by wide expanses of northern seas. At most only a few strongly arctic-adapted species could have persisted through the Pleistocene and no land bridges from the continents have existed since the Early Miocene, 20 million years ago.Southern Greenland, Iceland, and the Faeroes have been colonized across sea passages from the adjacent continents, mainly by air but partly by sea, during the postglacial period (ca. 10 000 years). The faunas are all young, with no endemic species among about 2000 in all; the faunas are not arctic but distinctly subarctic, mainly of the High and Low Boreal life zones, and derived from these life zones of North America or Europe. The naturally established faunas are small or very small, less than 14% of the corresponding continental faunas, and are obviously disharmonic, with some groups absent across the North Atlantic, e.g. Culicidae, Tabanidae, Tachinidae, Papilionoidea, aculeate Hymenoptera (except Bombus sp.). This indicates a severe "sweepstakes" route. The lack of Tachinidae is noteworthy because their hosts are plentiful, and indicates dispersal by air, with adult Tachinidae, unlike adult Lepidoptera, unable to make the journey; dispersal by a land bridge would offer parasites and hosts an equal opportunity. Aerial transport is indicated also by the high proportion of migrant species (of Lepidoptera) in the island faunas, and the arrival in Surtsey (a new volcanic island) of almost 25% of the Icelandic fauna in 12 years. The Surtsey observations suggest that the Icelandic fauna is preadapted to aerial dispersal, by selection during its journey from Europe.The fauna of southern Greenland is derived partly from boreal America and partly from boreal Europe. The North American moiety becomes vestigial in Iceland and the Faeroes and does not reach Europe. Iceland and the Faeroes have been populated from northwestern Europe, especially Britain and Scandinavia. A few species extend to southern Greenland and thence, or even directly, reach North America, and have thus completed a post-glacial traverse of the North Atlantic.The fauna of North Greenland differs fundamentally from all the above. It is a high arctic fauna, nearly identical with the high arctic fauna in Canada, and thus complete, not disharmonie, though very small by virtue of its high arctic nature. It has encountered no "sweepstakes" dispersal. North Greenland is separated from High Arctic Canada only by a narrow channel which permits winter dispersal by wind across unbroken sea ice. Biologically, North Greenland is part of the North American High Arctic, and although certain species (e.g. mosquitoes and butterflies) may extend somewhat into southern Greenland, it has not contributed to the basic faunas of the North Atlantic islands.Among other problems, the extreme variability in wing pattern of many Lepidoptera in Iceland, the Faeroes, and Shetland is also commented on.

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