Moisture origin, transport pathways, and driving processes of intense wintertime moisture transport into the Arctic

Abstract. A substantial portion of the moisture transport into the Arctic occurs in episodic, high-amplitude events with strong impacts on the Arctic's climate system components such as sea ice. This study focuses on the origin of such moist-air intrusions during winter and examines the moisture sources, moisture transport pathways, and their linkage to the driving large-scale circulation patterns. For that purpose, 597 moist-air intrusions, defined as daily events of intense (exceeding the 90th anomaly percentile) zonal mean moisture transport into the polar cap (≥70∘ N), are identified. Kinematic backward trajectories combined with a Lagrangian moisture source diagnostic are then used to pinpoint the moisture sources and characterize the airstreams accomplishing the transport. The moisture source analyses show that the bulk of the moisture transported into the polar cap during these moist-air intrusions originates in the eastern North Atlantic with an uptake maximum poleward of 50∘ N. Trajectories further reveal an inverse relationship between moisture uptake latitude and the level at which moisture is injected into the polar cap, consistent with ascent of poleward-flowing air in a baroclinic atmosphere. Focusing on intrusions in the North Atlantic (424 intrusions), we find that lower tropospheric moisture transport is predominantly accomplished by two types of airstreams: (i) cold, polar air warmed and moistened by surface fluxes and (ii) air subsiding from the mid-troposphere into the boundary layer. Both airstreams contribute about 36 % each to the total transport. The former accounts for most of the moisture transport during intrusions associated with an anomalously high frequency of cyclones east of Greenland (218 intrusions), whereas the latter is more important in the presence of atmospheric blocking over Scandinavia and the Ural Mountains (145 events). Long-range moisture transport, accounting for 17 % of the total transport, dominates during intrusions with weak forcing by baroclinic weather systems (64 intrusions). Finally, mid-tropospheric moisture transport is invariably associated with (diabatically) ascending air and moisture origin in the central and western North Atlantic, including the Gulf Stream front, accounting for roughly 10 % of the total transport. In summary, our study shows that moist-air intrusions into the polar atmosphere result from a combination of airstreams with predominantly high-latitude or high-altitude origin, whose relative importance is determined by the underlying driving weather systems (i.e., cyclones and blocks).

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Moisture origin, transport pathways, and driving processes of intense wintertime moisture transport into the Arctic

10.5194/wcd-2021-57 ◽

2021 ◽

Author(s):

Lukas Papritz ◽

David Hauswirth ◽

Katharina Hartmuth

Keyword(s):

North Atlantic ◽

Moisture Transport ◽

Large Scale ◽

The Arctic ◽

Polar Cap ◽

Transport Pathways ◽

Moisture Sources ◽

The North ◽

Total Transport ◽

Air Streams

Abstract. Poleward moisture transport occurs in episodic, high-amplitude events with strong impacts on the Arctic and its climate system components such as sea ice. This study focuses on the origin of such events and examines the moisture sources, moisture transport pathways, and their linkage to the large-scale circulation. For that purpose, 597 events of intense zonal mean poleward moisture transport at 70° N (exceeding the 90th anomaly percentile) are identified and kinematic backward trajectories from 70° N are computed to pinpoint the moisture sources and characterize the air-streams accomplishing the transport. The bulk of the moisture transported into the polar cap during these events originates in the eastern North Atlantic with an uptake maximum poleward of 50° N. This asymmetry between ocean basins is a direct consequence of the fact that most of the moisture transport into the polar cap occurs in this sector. As a result of the fairly high-latitude origin of the moisture, the median time moisture spends in the atmosphere prior to reaching 70° N amounts to about 2.5 days. Trajectories further reveal an inverse relationship between moisture uptake latitude and the level at which moisture is injected into the polar cap, consistent with ascent of poleward flowing air in a baroclinic atmosphere. Focusing on events for which 75 % of the zonal mean moisture transport takes place in the North Atlantic east of Greenland (424 events) reveals that lower tropospheric moisture transport results predominantly from two types of air-streams: (i) cold, polar air advected from the Canadian Arctic over the North Atlantic and around Greenland, whereby the air is warmed and moistened by surface fluxes, and (ii) air subsiding from the mid-troposphere into the boundary layer. Both air-streams contribute about 36 % each to the total transport. The former dominates the moisture transport during events associated with an anomalously high frequency of cyclones east of Greenland (218 events), whereas the latter is more important in the presence of atmospheric blocking over Scandinavia and the Ural (145 events). A substantial portion of the moisture sources associated with both types of air-streams are located between Iceland, the British Isles, and Norway. Long-range moisture transport, accounting for 17 % of the total transport, is the dominant type of air-stream during events with weak forcing by baroclinic weather systems (64 events). Finally, mid-tropospheric moisture transport is invariably associated with (diabatically) ascending air and moisture origin in the central and western North Atlantic, including the Gulf Stream front, accounting for roughly 10 % of the total transport. In summary, our study reveals that moisture injections into the polar atmosphere are not primarily caused by the poleward transport of warm and humid air from low latitudes – a conclusion that applies in particular to cases where the transport is driven by baroclinic weather systems such as extratropical cyclones. Instead, it results from a combination of air-streams with pre-dominantly high-latitude or high-altitude origin and their interplay with large-scale weather systems (e.g., cyclones, blocks).

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Lagrangian detection of moisture sources for an arid region in Northeast Greenland: relations to the North-Atlantic Oscillation and temporal trends from 1979 to 2017

10.5194/egusphere-egu2020-11507 ◽

2020 ◽

Author(s):

Lilian Schuster ◽

Fabien Maussion ◽

Lukas Langhamer ◽

Gina E. Moseley

Keyword(s):

North Atlantic Oscillation ◽

North Atlantic ◽

Arid Region ◽

North Atlantic Ocean ◽

Temporal Trends ◽

Reanalysis Data ◽

The Arctic ◽

Study Region ◽

Moisture Source ◽

Moisture Sources

Northeast Greenland is predicted to be one of the most sensitive terrestrial areas of the Arctic to anthropogenic climate change, resulting in an increase in temperature that is much greater than the global average. Associated with this temperature rise, precipitation is also expected to increase as a result of increased evaporation from an ice-free Arctic Ocean. In recent years, numerous palaeoclimate projects have begun working in the region with the aim of improving our understanding of how this highly-sensitive region responds to a warmer world. However, a lack of meteorological stations within the area makes it difficult to place the palaeoclimate records in the context of modern climate.This study aims to improve our understanding of precipitation and moisture source dynamics over a small arid region located at 80 &#176;N in Northeast Greenland. This region hosts many speleothem-containing caves that are being studied in the framework of the Greenland Caves Project (greenlandcavesproject.org). The origin of water vapour for precipitation over the study site is detected by a Lagrangian moisture source diagnostic, which is applied to reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA-Interim) from 1979 to 2017.While precipitation amounts are relatively constant during the year, the regional moisture sources display a strong seasonality. The most dominant winter moisture sources are the ice-free North Atlantic ocean above 45 &#176;N, while in summer the patterns shift towards more local and North Eurasian continental sources. During positive North-Atlantic Oscillation (NAO) phases evaporation and moisture transport from the Norwegian Sea is stronger, resulting in larger and more variable precipitation amounts. Although the annual mean temperature in the study region has increased by 0.7 &#176;C dec -1 (95% confidence interval [0.4, 1.0] &#176;C dec -1 ) according to ERA-Interim data, we do not detect any change in the amount of precipitation with the exception of autumn where precipitation increases by 8.2 [0.8, 15.5] mm dec&#160;-1 over the period. This increase is consistent with future predicted Arctic precipitation change.

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Sources and transport pathways of precipitating waters in cold-season deep North Atlantic cyclones

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-21-0105.1 ◽

2021 ◽

Author(s):

Lukas Papritz ◽

Franziska Aemisegger ◽

Heini Wernli

Keyword(s):

North Atlantic ◽

Gulf Stream ◽

Water Cycle ◽

Storm Track ◽

Cold Season ◽

Surface Fluxes ◽

Extratropical Cyclones ◽

Transport Pathways ◽

The North ◽

Cyclone Tracking

AbstractExtratropical cyclones are responsible for a large share of precipitation at mid-latitudes and they profoundly impact the characteristics of the water cycle. In this study, we use the ERA5 reanalysis and a cyclone tracking scheme combined with a Lagrangian diagnostic to identify the sources of moisture precipitating close to the center of 676 deep North Atlantic cyclones in winters 1979 to 2018. Moisture uptakes occur pre-dominantly in originally cold and dry air heated over the North Atlantic, in particular, over the warm waters of the Gulf Stream, whereas more remote sources from land or the subtropics are less important. Analysing the dynamical environment of moisture uptakes, we find that moisture precipitating during the cyclone intensification phase originates in the pre-cyclone environment in the cold sectors of preceding cyclones and the cyclone-anticyclone interaction zone. These moisture sources are linked to the cyclone’s ascent regions via the so-called feeder airstream, a north-easterly cyclone-relative flow that arises due to the cyclone propagation exceeding the advection by the low-level background flow. During the decay phase more and more of the moisture originates in the cyclone’s own cold sector. Consequently, the residence time of precipitating waters in cyclones is short (median of ≈ 2 days) and transport distances are typically less than the distance travelled by the cyclone itself. These findings emphasize the importance of pre-conditioning by surface fluxes in the pre-cyclone environment for the formation of precipitation in cyclones, and suggest an important role for the hand-over of moisture from one cyclone to the next within a storm track.

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The role of moisture transport for precipitation in the inter-annual and inter-daily fluctuations of the Arctic sea ice extension

Earth System Dynamics ◽

10.5194/esd-10-121-2019 ◽

2019 ◽

Vol 10 (1) ◽

pp. 121-133 ◽

Cited By ~ 3

Author(s):

Luis Gimeno-Sotelo ◽

Raquel Nieto ◽

Marta Vázquez ◽

Luis Gimeno

Keyword(s):

Sea Ice ◽

Moisture Transport ◽

Arctic Region ◽

Arctic Sea Ice ◽

The Arctic ◽

Ice Melting ◽

Sea Ice Extent ◽

Moisture Sources ◽

Arctic Sea

Abstract. By considering the moisture transport for precipitation (MTP) for a target region to be the moisture that arrives in this region from its major moisture sources and which then results in precipitation in that region, we explore (i) whether the MTP from the main moisture sources for the Arctic region is linked with inter-annual fluctuations in the extent of Arctic sea ice superimposed on its decline and (ii) the role of extreme MTP events in the inter-daily change in the Arctic sea ice extent (SIE) when extreme MTP simultaneously arrives from the four main moisture regions that supply it. The results suggest (1) that ice melting at the scale of inter-annual fluctuations against the trend is favoured by an increase in moisture transport in summer, autumn, and winter and a decrease in spring and, (2) on a daily basis, extreme humidity transport increases the formation of ice in winter and decreases it in spring, summer, and autumn; in these three seasons extreme humidity transport therefore contributes to Arctic sea ice melting. These patterns differ sharply from that linked to the decline on a long-range scale, especially in summer when the opposite trend applies, as ice melt is favoured by a decrease in moisture transport for this season at this scale.

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Heat transport pathways into the Arctic and their connections to surface air temperatures

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-3927-2019 ◽

2019 ◽

Vol 19 (6) ◽

pp. 3927-3937 ◽

Cited By ~ 7

Author(s):

Daniel Mewes ◽

Christoph Jacobi

Keyword(s):

North Atlantic ◽

North Pacific ◽

Large Scale ◽

The Arctic ◽

Positive Temperature ◽

Transport Pathways ◽

Temperature Anomalies ◽

The North ◽

The North Atlantic ◽

The North Pacific

Abstract. Arctic amplification causes the meridional temperature gradient between middle and high latitudes to decrease. Through this decrease the large-scale circulation in the midlatitudes may change and therefore the meridional transport of heat and moisture increases. This in turn may increase Arctic warming even further. To investigate patterns of Arctic temperature, horizontal transports and their changes in time, we analysed ERA-Interim daily winter data of vertically integrated horizontal moist static energy transport using self-organizing maps (SOMs). Three general transport pathways have been identified: the North Atlantic pathway with transport mainly over the northern Atlantic, the North Pacific pathway with transport from the Pacific region, and the Siberian pathway with transport towards the Arctic over the eastern Siberian region. Transports that originate from the North Pacific are connected to negative temperature anomalies over the central Arctic. These North Pacific pathways have been becoming less frequent during the last decades. Patterns with origin of transport in Siberia are found to have no trend and show cold temperature anomalies north of Svalbard. It was found that transport patterns that favour transport through the North Atlantic into the central Arctic are connected to positive temperature anomalies over large regions of the Arctic. These temperature anomalies resemble the warm Arctic–cold continents pattern. Further, it could be shown that transport through the North Atlantic has been becoming more frequent during the last decades.

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Lagrangian detection of precipitation moisture sources for an arid region in northeast Greenland: relations to the North Atlantic Oscillation, sea ice cover, and temporal trends from 1979 to 2017

Weather and Climate Dynamics ◽

10.5194/wcd-2-1-2021 ◽

2021 ◽

Vol 2 (1) ◽

pp. 1-17

Author(s):

Lilian Schuster ◽

Fabien Maussion ◽

Lukas Langhamer ◽

Gina E. Moseley

Keyword(s):

Sea Ice ◽

North Atlantic Oscillation ◽

North Atlantic ◽

Arid Region ◽

Study Region ◽

Moisture Source ◽

Moisture Sources ◽

The North ◽

The North Atlantic ◽

The North Atlantic Oscillation

Abstract. Temperature in northeast Greenland is expected to rise at a faster rate than the global average as a consequence of anthropogenic climate change. Associated with this temperature rise, precipitation is also expected to increase as a result of increased evaporation from a warmer and ice-free Arctic Ocean. In recent years, numerous palaeoclimate projects have begun working in the region with the aim of improving our understanding of how this highly sensitive region responds to a warmer world. However, a lack of meteorological stations within the area makes it difficult to place the palaeoclimate records in the context of present-day climate. This study aims to improve our understanding of precipitation and moisture source dynamics over a small arid region located at 80∘ N in northeast Greenland. The origin of water vapour for precipitation over the study region is detected by a Lagrangian moisture source diagnostic, which is applied to reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA-Interim) from 1979 to 2017. While precipitation amounts are relatively constant during the year, the regional moisture sources display a strong seasonality. The most dominant winter moisture sources are the North Atlantic above 45∘ N and the ice-free Atlantic sector of the Arctic Ocean, while in summer the patterns shift towards local and north Eurasian continental sources. During the positive phases of the North Atlantic Oscillation (NAO), evaporation and moisture transport from the Norwegian Sea are stronger, resulting in larger and more variable precipitation amounts. Testing the hypothesis that retreating sea ice will lead to an increase in moisture supply remains challenging based on our data. However, we found that moisture sources are increasing in the case of retreating sea ice for some regions, in particular in October to December. Although the annual mean surface temperature in the study region has increased by 0.7 ∘C per decade (95 % confidence interval [0.4, 1.0] ∘C per decade) according to ERA-Interim data, we do not detect any change in the amount of precipitation with the exception of autumn where precipitation increases by 8.2 [0.8, 15.5] mm per decade over the period. This increase is consistent with future predicted Arctic precipitation change. Moisture source trends for other months and regions were non-existent or small.

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Lagrangian detection of precipitation moisture sources for an arid region in northeast Greenland: relations to the North Atlantic Oscillation, sea ice cover and temporal trends from 1979 to 2017

10.5194/wcd-2020-42 ◽

2020 ◽

Author(s):

Lilian Schuster ◽

Fabien Maussion ◽

Lukas Langhamer ◽

Gina E. Moseley

Keyword(s):

Sea Ice ◽

North Atlantic Oscillation ◽

North Atlantic ◽

Arid Region ◽

Study Region ◽

Moisture Source ◽

Moisture Sources ◽

The North ◽

The North Atlantic ◽

The North Atlantic Oscillation

Abstract. Temperature in northeast Greenland is expected to rise at a faster rate than the global average as consequence of anthropogenic climate change. Associated with this temperature rise, precipitation is also expected to increase as a result of increased evaporation from a warmer and ice-free Arctic Ocean. In recent years, numerous palaeoclimate projects have begun working in the region with the aim of improving our understanding of how this highly-sensitive region responds to a warmer world. However, a lack of meteorological stations within the area makes it difficult to place the palaeoclimate records in the context of present-day climate. This study aims to improve our understanding of precipitation and moisture source dynamics over a small arid region located at 80° N in northeast Greenland. The origin of water vapour for precipitation over the study region is detected by a Lagrangian moisture source diagnostic, which is applied to reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA-Interim) from 1979 to 2017. While precipitation amounts are relatively constant during the year, the regional moisture sources display a strong seasonality. The most dominant winter moisture sources are the North Atlantic above 45° N and the ice-free Atlantic sector of the Arctic Ocean, while in summer the patterns shift towards local and north Eurasian continental sources. During the positive phases of the North Atlantic Oscillation (NAO), evaporation and moisture transport from the Norwegian Sea is stronger, resulting in larger and more variable precipitation amounts. Testing the hypothesis that retreating sea ice will lead to increase in moisture supply remains challenging based on our data. However, we found that moisture sources are increasing in case of retreating sea ice for some regions, in particular in October to December. Although the annual mean surface temperature in the study region has increased by 0.7 °C dec-1 (95 % confidence interval [0.4, 1.0] °C dec-1) according to ERA-Interim data, we do not detect any change in the amount of precipitation with the exception of autumn where precipitation increases by 8.2 [0.8, 15.5] mm dec-1 over the period. This increase is consistent with future predicted Arctic precipitation change. Moisture source trends for other months and regions were non-existent or small.

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Local and External Moisture Sources for the Arctic Warming over the Barents–Kara Seas

Journal of Climate ◽

10.1175/jcli-d-17-0203.1 ◽

2018 ◽

Vol 31 (5) ◽

pp. 1963-1982 ◽

Cited By ~ 18

Author(s):

Linhao Zhong ◽

Lijuan Hua ◽

Dehai Luo

Keyword(s):

Sea Ice ◽

North Atlantic ◽

High Latitude ◽

Wave Train ◽

Recent Decade ◽

Arctic Sea Ice ◽

The Arctic ◽

Arctic Warming ◽

Moisture Sources ◽

Local Moisture

Water vapor is critical to Arctic sea ice loss and surface air warming, particularly in winter. Whether the local process or poleward transport from lower latitudes can explain the Arctic warming is still a controversial issue. In this work, a hydrological tool, a dynamical recycling model (DRM) based on time-backward Lagrangian moisture tracking, is applied to quantitatively evaluate the relative contributions of local evaporation and external sources to Barents–Kara Seas (BKS) moisture in winter during 1979–2015. On average, the local and external moistures explain 35.4% and 57.3% of BKS moisture, respectively. The BKS, Norwegian Sea, and midlatitude North Atlantic are the three major sources and show significant increasing trends of moisture contribution. The local moisture contribution correlates weakly to downward infrared radiation (IR) but significantly to sea ice variation, which suggests that the recent-decade increase of local moisture contribution is only a manifestation of sea ice melting. In contrast, the external moisture contribution significantly correlates to both downward IR and sea ice variation, thus suggesting that meridional moisture transport mainly explains the recent BKS warming. The moisture contributions due to different sources are governed by distinct circulation patterns. The negative Arctic Oscillation–like pattern suppresses external moisture but favors local evaporation. In the case of dominant external moisture, a well-organized wave train spanning from across the midlatitude Atlantic to mid–high-latitude Eurasia has the mid–high-latitude components similar to a positive-phase North Atlantic Oscillation with a Ural blocking to the east. Moreover, the meridional shift of the wave train pathway and the spatial scale of the wave train anomalies determine the transport passage and strength of the major external moisture sources.

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Forty-year climatology and variability of atmospheric rivers in the Arctic using MERRA-2 reanalysis from 1980 to 2020

10.5194/egusphere-egu21-14554 ◽

2021 ◽

Author(s):

Carolina Viceto ◽

Irina Gorodetskaya ◽

Annette Rinke ◽

Alfredo Rocha ◽

Susanne Crewell

Keyword(s):

Moisture Transport ◽

Barents Sea ◽

Arctic Region ◽

Gulf Of Alaska ◽

Water Vapor Transport ◽

The Arctic ◽

Research Centre ◽

Historical Period ◽

Transport Pathways ◽

Atmospheric Rivers

A significant increase in the atmospheric moisture content over the Arctic region has been recently documented, that might be caused by the enhanced poleward moisture flux which is expected to continuously increase in the future. This change can be attributed to different causes, in which increasing moisture transport intensity is included. In this study we focus on events with anomalous moisture transport confined to long, narrow and transient corridors, known as atmospheric rivers (ARs), which are expected to have a strong influence on Arctic mass and energy budget.This study is based on MERRA-2 reanalysis (Modern-Era Retrospective analysis for Research and Applications, Version 2) extending from an historical period until present (1980-2020). ARs are identified using the tracking algorithms by Gorodetskaya et al. (2020) and Guan et al. (2018). We explored the frequency of ARs focusing on annual, seasonal and monthly values. Spatial patterns were analysed for the Arctic latitudes, covering both Atlantic and Pacific moisture transport pathways, and showing the importance of the Siberian moisture pathway during summer. Furthermore, we include a more detailed analysis performed at different sites north of the Arctic circle. Specific attention is given to the ARs characteristics during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from September 2019 to October 2020, as compared to the forty-year climatology and variability of the ARs in the Arctic.Preliminary results show a higher frequency of ARs over the Norwegian and Barents Sea (Atlantic pathway), mainly during autumn and winter, although during May and June there is a high frequency of ARs over Western Siberia and Barents Sea. In contrast, the Canadian Artic has a lower frequency of ARs regardless the season, which is explained by a steep decrease of ARs frequency in the Gulf of Alaska and Bering Sea that block their progression to further north latitudes.&#160;References: Gorodetskaya, I. V., Silva, T., Schmith&#252;sen, H., and Hirasawa, N., 2020: Atmospheric River Signatures in Radiosonde Profiles and Reanalyses at the Dronning Maud Land Coast, East Antarctica. Adv. Atmos. Sci.,&#160;https://doi.org/10.1007/s00376-020-9221-8.Guan, B., Waliser, D. E. and Ralph, F. M., 2018: An Intercomparison between Reanalysis and Dropsonde Observations of the Total Water Vapor Transport in Individual Atmospheric Rivers. J. Hydrometeorol., 19, 321&#8211;337, https://doi.org/10.1175/JHM-D-17-0114.1.&#160;Acknowledgments: This work is supported by FCT PhD Grant SFRH/BD/129154/2017 and developed in collaboration with Transregional Collaborative Research Centre (AC)3, AWI and U. Cologne.

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A Regional Thermohaline Inverse Method for Estimating Circulation and Mixing in the Arctic and Subpolar North Atlantic

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-17-0198.1 ◽

2018 ◽

Vol 35 (12) ◽

pp. 2383-2403 ◽

Cited By ~ 3

Author(s):

Neill Mackay ◽

Chris Wilson ◽

Jan Zika ◽

N. Penny Holliday

Keyword(s):

North Atlantic ◽

Inverse Method ◽

Surface Fluxes ◽

Meridional Overturning Circulation ◽

The Arctic ◽

Surface Boundary ◽

The South ◽

Overturning Circulation ◽

Transformation Rates ◽

Meridional Overturning

AbstractA regional thermohaline inverse method (RTHIM) is presented that estimates velocities through the section bounding an enclosed domain and transformation rates resulting from interior mixing within the domain, given inputs of surface boundary fluxes of heat and salt and interior distributions of salinity and temperature. The method works by invoking a volumetric balance in thermohaline coordinates between the transformation resulting from mixing, surface fluxes, and advection, and constraining the mixing to be down tracer gradients. The method is validated using a 20-yr mean of outputs from the NEMO model in an Arctic and subpolar North Atlantic domain, bound to the south by a section with a mean latitude of 66°N. RTHIM solutions agree well with the NEMO model “truth” and are robust to a range of parameters; the meridional overturning circulation (MOC), heat, and freshwater transports calculated from an ensemble of RTHIM solutions are within 12%, 10%, and 19%, respectively, of the NEMO values. There is also bulk agreement between RTHIM solution transformation rates resulting from mixing and those diagnosed from NEMO. Localized differences in diagnosed mixing may be used to guide the development of mixing parameterizations in models such as NEMO, whose downgradient diffusive closures with prescribed diffusivity may be considered oversimplified and too restrictive.

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