Winter season variability in North American Prairie SWE distribution and atmospheric circulation

AbstractThe interannual variability of wintertime North American surface temperature extremes and its generation and maintenance are analyzed in this study. The leading mode of the temperature extreme anomalies, revealed by empirical orthogonal function (EOF) analyses of December–February mean temperature extreme indices over North America, is characterized by an anomalous center of action over western-central Canada. In association with the leading mode of temperature extreme variability, the large-scale atmospheric circulation features an anomalous Pacific–North American (PNA)-like pattern from the preceding fall to winter, which has important implications for seasonal prediction of North American temperature extremes. A positive PNA pattern leads to more warm and fewer cold extremes over western-central Canada. The anomalous circulation over the PNA sector drives thermal advection that contributes to temperature anomalies over North America, as well as a Pacific decadal oscillation (PDO)-like sea surface temperature (SST) anomaly pattern in the midlatitude North Pacific. The PNA-like circulation anomaly tends to be supported by SST warming in the tropical central-eastern Pacific and a positive synoptic-scale eddy vorticity forcing feedback on the large-scale circulation over the PNA sector. The leading extreme mode–associated atmospheric circulation patterns obtained from the observational and reanalysis data, together with the anomalous SST and synoptic eddy activities, are reasonably well simulated in most CMIP5 models and in the multimodel mean. For most models considered, the simulated patterns of atmospheric circulation, SST, and synoptic eddy activities have lower spatial variances than the corresponding observational and reanalysis patterns over the PNA sector, especially over the North Pacific.

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How might the North American ice sheet influence the northwestern Eurasian climate?

Climate of the Past ◽

10.5194/cp-11-1467-2015 ◽

2015 ◽

Vol 11 (10) ◽

pp. 1467-1490 ◽

Cited By ~ 8

Author(s):

P. Beghin ◽

S. Charbit ◽

C. Dumas ◽

M. Kageyama ◽

C. Ritz

Keyword(s):

Atmospheric Circulation ◽

North American ◽

Gradual Increase ◽

Ice Sheets ◽

Ice Sheet ◽

Total Precipitation ◽

Surface Mass ◽

The North ◽

Albedo Effect ◽

Eurasian Region

Abstract. It is now widely acknowledged that past Northern Hemisphere ice sheets covering Canada and northern Europe at the Last Glacial Maximum (LGM) exerted a strong influence on climate by causing changes in atmospheric and oceanic circulations. In turn, these changes may have impacted the development of the ice sheets themselves through a combination of different feedback mechanisms. The present study is designed to investigate the potential impact of the North American ice sheet on the surface mass balance (SMB) of the Eurasian ice sheet driven by simulated changes in the past glacial atmospheric circulation. Using the LMDZ5 atmospheric circulation model, we carried out 12 experiments under constant LGM conditions for insolation, greenhouse gases and ocean. In these experiments, the Eurasian ice sheet is removed. The 12 experiments differ in the North American ice-sheet topography, ranging from a white and flat (present-day topography) ice sheet to a full-size LGM ice sheet. This experimental design allows the albedo and the topographic impacts of the North American ice sheet onto the climate to be disentangled. The results are compared to our baseline experiment where both the North American and the Eurasian ice sheets have been removed. In summer, the sole albedo effect of the American ice sheet modifies the pattern of planetary waves with respect to the no-ice-sheet case, resulting in a cooling of the northwestern Eurasian region. By contrast, the atmospheric circulation changes induced by the topography of the North American ice sheet lead to a strong decrease of this cooling. In winter, the Scandinavian and the Barents–Kara regions respond differently to the American ice-sheet albedo effect: in response to atmospheric circulation changes, Scandinavia becomes warmer and total precipitation is more abundant, whereas the Barents–Kara area becomes cooler with a decrease of convective processes, causing a decrease of total precipitation. The gradual increase of the altitude of the American ice sheet leads to less total precipitation and snowfall and to colder temperatures over both the Scandinavian and the Barents and Kara sea sectors. We then compute the resulting annual surface mass balance over the Fennoscandian region from the simulated temperature and precipitation fields used to force an ice-sheet model. It clearly appears that the SMB is dominated by the ablation signal. In response to the summer cooling induced by the American ice-sheet albedo, high positive SMB values are obtained over the Eurasian region, leading thus to the growth of an ice sheet. On the contrary, the gradual increase of the American ice-sheet altitude induces more ablation over the Eurasian sector, hence limiting the growth of Fennoscandia. To test the robustness of our results with respect to the Eurasian ice sheet state, we carried out two additional LMDZ experiments with new boundary conditions involving both the American (flat or full LGM) and high Eurasian ice sheets. The most striking result is that the Eurasian ice sheet is maintained under full-LGM North American ice-sheet conditions, but loses ~ 10 % of its mass compared to the case in which the North American ice sheet is flat. These new findings qualitatively confirm the conclusions from our first series of experiments and suggest that the development of the Eurasian ice sheet may have been slowed down by the growth of the American ice sheet, offering thereby a new understanding of the evolution of Northern Hemisphere ice sheets throughout glacial–interglacial cycles.

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Influence of native North American prairie grasses on predation of an insect herbivore of potato

Biological Control ◽

10.1016/j.biocontrol.2011.11.009 ◽

2012 ◽

Vol 61 (1) ◽

pp. 15-25 ◽

Cited By ~ 6

Author(s):

Ben P. Werling ◽

Jason Harmon ◽

Cory Straub ◽

Claudio Gratton

Keyword(s):

North American ◽

Insect Herbivore ◽

Native North American ◽

Prairie Grasses ◽

North American Prairie

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Relationship between Water Temperature of Polish Rivers and Large-Scale Atmospheric Circulation

Water ◽

10.3390/w11081690 ◽

2019 ◽

Vol 11 (8) ◽

pp. 1690 ◽

Cited By ~ 4

Author(s):

Renata Graf ◽

Dariusz Wrzesiński

Keyword(s):

Water Temperature ◽

Atmospheric Circulation ◽

Large Scale ◽

Statistical Significance ◽

Winter Season ◽

Circulation Type ◽

River Waters ◽

Positive And Negative Coefficients ◽

Circulation Types ◽

Temporal And Spatial Variability

The objective of the paper consisted in determining the effect of macroscale types of NAO, AO, EA, EAWR, SCAND, and AMO atmospheric circulation on changes in water temperature in Polish rivers. The study has made use of a broad body of hydrometeorological materials covering daily water temperature values for 96 water gauge stations located on 53 rivers and air temperature values for 43 meteorological stations. Percentage shares of positive and negative coefficients of correlation of annual, seasonal, and monthly circulation type indices with air and river water temperature were determined, demonstrating the character of teleconnection. Determinations were made of water temperature deviations in positive and negative phases of the analyzed indices from average values from the years 1971–2015, and their statistical significance ascertained. Research has shown that relations between the temperature of river waters in Poland and macroscale circulation types are not strong, however they are noticeable, sometimes even statistically significant, and both temporally and spatially diverse. NAO, AO, EA, and AMO indices are characterized by a generally positive correlation with temperature, whereas SCAND and EWAR indices are characterized by a negative correlation. Research showed a varying impact of types of atmospheric circulation, with their effectiveness increasing in the winter season. The strongest impact on temperature was observed for the positive and negative NAO and AO phases, when deviations of water temperature from average values are correspondingly higher (up to 1.0 °C) and lower (by a maximum of 1.5 °C), and also for the positive and negative SCAND phases, when water temperature are correspondingly lower (by a maximum of 0.8 °C) and higher (by 1.2 °C) than average values. The strongest impact on water temperature in summer, mainly in July, was observed for AMO. The results point to the complexity of processes determining the thermal regime of rivers and to the possibility of additional factors—both regional and local—exerting an influence on their temporal and spatial variability.

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Two types of North American droughts related to different atmospheric circulation patterns

Climate of the Past ◽

10.5194/cp-15-2053-2019 ◽

2019 ◽

Vol 15 (6) ◽

pp. 2053-2065 ◽

Cited By ~ 1

Author(s):

Angela-Maria Burgdorf ◽

Stefan Brönnimann ◽

Jörg Franke

Keyword(s):

Atmospheric Circulation ◽

Great Plains ◽

North Atlantic ◽

North American ◽

Wave Train ◽

Boreal Summer ◽

Drought Indices ◽

Dust Bowl ◽

Summer Drought ◽

The Pacific

Abstract. Proxy-based studies suggest that the southwestern USA is affected by two types of summer drought, often termed Dust Bowl-type droughts and 1950s-type droughts. The spatial drought patterns of the two types are distinct. It has been suggested that they are related to different circulation characteristics, but a lack of observation-based data has precluded further studies. In this paper, we analyze multi-annual summer droughts in North America back to 1600 in tree-ring-based drought reconstructions and in a global, monthly three-dimensional reconstruction of the atmosphere. Using cluster analysis of drought indices, we confirm the two main drought types and find a similar catalog of events as previous studies. These two main types of droughts are then analyzed with respect to 2 m temperatures (T2m), sea-level pressure (SLP), and 500 hPa geopotential height (GPH) in boreal summer. 1950s-type droughts are related to a stronger wave train over the Pacific–North American sector than Dust Bowl-type droughts, whereas the latter show the imprint of a poleward-shifted jet and establishment of a Great Plains ridge. The 500 hPa GPH patterns of the two types differ significantly not only over the contiguous United States and Canada but also over the extratropical North Atlantic and the Pacific. Dust Bowl-type droughts are associated with positive GPH anomalies, while 1950s-type droughts exhibit strong negative GPH anomalies. In comparison with 1950s-type droughts, the Dust Bowl-type droughts are characterized by higher sea-surface temperatures (SSTs) in the northern North Atlantic. Results suggest that atmospheric circulation and SST characteristics not only over the Pacific but also over the extratropical North Atlantic affect the spatial pattern of North American droughts.

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Mechanization and North American Prairie Farm Costs 1896–1930

The Journal of Economic History ◽

10.1017/s002205070002708x ◽

1982 ◽

Vol 42 (1) ◽

pp. 199-206 ◽

Cited By ~ 1

Author(s):

Trevor J. O. Dick

Keyword(s):

Twentieth Century ◽

Learning Process ◽

North American ◽

Cost Savings ◽

Entire Period ◽

Continuous Learning ◽

Yield Data ◽

Farm Machinery ◽

Ex Post ◽

North American Prairie

This paper attempts to document and account for cost savings on North American small-grain prairie farms in the early twentieth century. Costs of production are analyzed using the ex post price and yield data abundantly available. Cost conjectures are developed and compared with scattered farm data that itemize inputs and reveal some aspects of farming technique. Total costs per acre, despite year to year fluctuations, appear to have fallen gradually over the entire period consistent with a comprehensive and continuous learning process, rather than only suddenly in the late 1920s when there was a marked increase in the sales of gasoline-powered farm machinery.

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