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

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

<p>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.</p><p>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. 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.</p><p>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 °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 °C dec <sup>-1</sup> (95% confidence interval [0.4, 1.0] °C dec <sup>-1</sup> ) 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 <sup>-1</sup> over the period. This increase is consistent with future predicted Arctic precipitation change.</p>

scholarly journals 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

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.

scholarly journals 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

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.

scholarly journals Long-term variations of the seasonal snow cover in Nordland, Norway: the influence of the North Atlantic Oscillation

2013 ◽  
Vol 54 (62) ◽  
pp. 25-34 ◽  
Author(s):  
Wilfred H. Theakstone
Keyword(s):  
North Atlantic Oscillation ◽  
Snow Cover ◽  
20Th Century ◽  
North Atlantic ◽  
Temporal Trends ◽  
The Arctic ◽  
Simple Task ◽  
Seasonal Snow ◽  
Synoptic Conditions ◽  
Seasonal Snow Cover

AbstractTemporal and spatial variations of the seasonal snow cover at 40 sites in Nordland county, Norway, since the last decade of the 19th century are examined. Nordland lies across the Arctic Circle. Annual maximum snow depths there have varied, reflecting the interaction of synoptic conditions, temperature and terrain. North/south and coastal/inland differences are evident, but common temporal trends are identified. Maximum snow depths are strongly related to the winter North Atlantic Oscillation index. Early in the 20th century, the index was positive and the associated stormy conditions resulted in a deep, prolonged snow cover. As the index declined in the 1920s, snow depths decreased sharply. Through much of the second half of the 20th century they increased as the index tended to become more positive. The start and duration of the period of continuous snow cover is influenced by the autumn NAO index. A decrease of duration around 1990 was particularly evident at low-lying stations and those in northern Nordland. The NAO has varied considerably over the past 120 years. Because of its influence, forecasting future trends of snow depth and snow-cover duration is not a simple task.

scholarly journals The Summer North Atlantic Oscillation Influence on the Eastern Mediterranean

2011 ◽  
Vol 24 (21) ◽  
pp. 5584-5596 ◽  
Author(s):  
Themis Chronis ◽  
Dionysios E. Raitsos ◽  
Dimitris Kassis ◽  
Athanassios Sarantopoulos
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Eastern Mediterranean ◽  
Reanalysis Data ◽  
The Arctic ◽  
Anatolian Plateau ◽  
Physical Mechanisms ◽  
Pressure Fields ◽  
Satellite Retrievals ◽  
Meteorological Observations

Abstract This study highlights an important and previously overlooked summer North Atlantic Oscillation (NAO) influence over the eastern Mediterranean. The featured analysis is based on a synergistic use of reanalysis data, satellite retrievals, and coastal and buoy meteorological observations. The physical mechanisms at play reveal a strong summer NAO involvement on the pressure fields over northern Europe and the Anatolian plateau. Especially during August, the summer NAO modulates the Anatolian low, together with the air temperature, meridional atmospheric circulation, and cloudiness over the eastern Mediterranean. Including the dominant action centers over Greenland and the Arctic, the identified modulations rank among the strongest summer NAO-related signals over the entire Northern Hemisphere.

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

2022 ◽  
Vol 3 (1) ◽  
pp. 1-20
Author(s):  
Lukas Papritz ◽  
David Hauswirth ◽  
Katharina Hartmuth
Keyword(s):  
North Atlantic ◽  
Moisture Transport ◽  
Surface Fluxes ◽  
The Arctic ◽  
Moist Air ◽  
Polar Cap ◽  
Transport Pathways ◽  
Moisture Source ◽  
Moisture Sources ◽  
Total Transport

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).

scholarly journals Cooling down the world oceans and the earth by enhancing the North Atlantic Ocean current

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Julian David Hunt ◽  
Andreas Nascimento ◽  
Fabio A. Diuana ◽  
Natália de Assis Brasil Weber ◽  
Gabriel Malta Castro ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Arctic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
The Arctic ◽  
Ocean Current ◽  
The North ◽  
The Arctic Ocean ◽  
Albedo Effect ◽  
Arctic Atmosphere

AbstractThe world is going through intensive changes due to global warming. It is well known that the reduction in ice cover in the Arctic Ocean further contributes to increasing the atmospheric Arctic temperature due to the reduction of the albedo effect and increase in heat absorbed by the ocean’s surface. The Arctic ice cover also works like an insulation sheet, keeping the heat in the ocean from dissipating into the cold Arctic atmosphere. Increasing the salinity of the Arctic Ocean surface would allow the warmer and less salty North Atlantic Ocean current to flow on the surface of the Arctic Ocean considerably increasing the temperature of the Arctic atmosphere and release the ocean heat trapped under the ice. This paper argues that if the North Atlantic Ocean current could maintain the Arctic Ocean ice-free during the winter, the longwave radiation heat loss into space would be larger than the increase in heat absorption due to the albedo effect. This paper presents details of the fundamentals of the Arctic Ocean circulation and presents three possible approaches for increasing the salinity of the surface water of the Arctic Ocean. It then discusses that increasing the salinity of the Arctic Ocean would warm the atmosphere of the Arctic region, but cool down the oceans and possibly the Earth. However, it might take thousands of years for the effects of cooling the oceans to cool the global average atmospheric temperature.

Decadal Relationship between European Blocking and the North Atlantic Oscillation during 1978–2011. Part II: A Theoretical Model Study

2015 ◽  
Vol 72 (3) ◽  
pp. 1174-1199 ◽  
Author(s):  
Dehai Luo ◽  
Yao Yao ◽  
Aiguo Dai
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Zonal Wind ◽  
Storm Track ◽  
Reanalysis Data ◽  
Western Atlantic ◽  
Atlantic Sector ◽  
Frequency Distributions ◽  
Peak Structure ◽  
The Mean

Abstract In Part I of this study, it is revealed that decadal variations of European blocking, in its intensity, duration, and position, during 1978–2011 are modulated by decadal changes in the frequency of North Atlantic Oscillation (NAO) events associated with background Atlantic conditions. In Part II, reanalysis data are analyzed to first show that a T-bone-type structure of the climatological-mean blocking frequency in the Euro-Atlantic sector roughly results from a combination of the blocking frequency distributions along the southeast–northwest (SE–NW) direction associated with negative-phase NAO (NAO−) events and along the southwest–northeast (SW–NE) direction associated with positive-phase NAO (NAO+) events. A nonlinear multiscale interaction (NMI) model is then used to examine the physical processes behind the blocking frequency distributions. This model shows that the combination of eastward- and westward-displaced blocking frequency patterns along the SW–NE and SE–NW directions associated with NAO+ and NAO− events leads to a T-bone-type frequency distribution, as seen in reanalysis data. Moreover, it is found that the westward migration of intense, long-lived blocking anomalies over Europe following NAO+ events is favored (suppressed) when the Atlantic mean zonal wind is relatively weak (strong). This result is held for the strong (weak) western Atlantic storm track. This helps explain the findings in Part I. In particular, long-lived blocking events with double peaks can form over Europe because of reintensification during the NAO+ decay phase, when the mean zonal wind weakens. But the double-peak structure disappears and becomes a strong single-peak structure as the mean zonal wind strengthens.

Tracking Moisture Sources of Precipitation over Central Asia: A Study Based on the Water-Source-Tagging Method

2020 ◽  
Vol 33 (23) ◽  
pp. 10339-10355
Author(s):  
Jie Jiang ◽  
Tianjun Zhou ◽  
Hailong Wang ◽  
Yun Qian ◽  
David Noone ◽  
...  
Keyword(s):  
Central Asia ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Northern Europe ◽  
Moisture Sources ◽  
The North ◽  
Westerly Jet ◽  
Drying Trend ◽  
The North Atlantic ◽  
Subtropical Westerly Jet

AbstractCentral Asia is a semiarid to arid region that is sensitive to hydrological changes. We use the Community Atmosphere Model, version 5 (CAM5), equipped with a water-tagging capability, to investigate the major moisture sources for climatological precipitation and its long-term trends over central Asia. Europe, the North Atlantic Ocean, and local evaporation, which explain 33.2% ± 1.5%, 23.0% ± 2.5%, and 19.4% ± 2.2% of the precipitation, respectively, are identified as the most dominant moisture sources for northern central Asia (NCA). For precipitation over southern central Asia (SCA), Europe, the North Atlantic, and local evaporation contribute 25.4% ± 2.7%, 18.0% ± 1.7%, and 14.7% ± 1.9%, respectively. In addition, the contributions of South Asia (8.6% ± 1.7%) and the Indian Ocean (9.5% ± 2.0%) are also substantial for SCA. Modulated by the seasonal meridional shift in the subtropical westerly jet, moisture originating from the low and midlatitudes is important in winter, spring, and autumn, whereas northern Europe contributes more to summer precipitation. We also explain the observed drying trends over southeastern central Asia in spring and over NCA in summer during 1956–2005. The drying trend over southeastern central Asia in spring is mainly due to the decrease in local evaporation and weakened moisture fluxes from the Arabian Peninsula and Arabian Sea associated with the warming of the western Pacific Ocean. The drying trend over NCA in summer can be attributed to a decrease in local evaporation and reduced moisture from northern Europe that is due to the southward shift of the subtropical westerly jet.

The North Atlantic Oscillation and the Arctic Oscillation favour harmful algal blooms in SW Europe

Harmful Algae ◽  
2014 ◽  
Vol 39 ◽  
pp. 121-126 ◽  
Author(s):  
José C. Báez ◽  
Raimundo Real ◽  
Victoria López-Rodas ◽  
Eduardo Costas ◽  
A. Enrique Salvo ◽  
...  
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Arctic Oscillation ◽  
The Arctic ◽  
The North ◽  
The North Atlantic ◽  
The Arctic Oscillation ◽  
The North Atlantic Oscillation
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