Steering of westerly storms over western North America at the Last Glacial Maximum

Oster, Jessica L.; Ibarra, Daniel E.; Winnick, Matthew J.; Maher, Kate

doi:10.1038/ngeo2365

Cited by 202 publications

(232 citation statements)

References 27 publications

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“…Compared with that of MIS 4, the MIS 2 Laurentide and Cordilleran ice sheets were much more extensive, spanning North America from west to east, and a large anticyclone developed above it in a midcontinental location (2). Combined with a strong north Pacific high-pressure system and a southward-displaced Aleutian Low, these features steered the jet stream south and away from the WR (2).…”

Section: Atmospheric Circulation During and After The Last Glacial Mamentioning

confidence: 99%

“…Developing this approach and applying it to midcontinent North America allow us to examine a nearly continuous record of the hydroclimates of the most recent glacial cycles in central North America, a region where records of such duration are otherwise unavailable. These data are then compared with other continental records and atmospheric circulation simulations (2,(5)(6)(7)(8)(9) to provide deeper insight into the spatial and temporal variabilities in North American paleoclimate.…”

mentioning

confidence: 99%

“…paleoclimate | carbon oxygen uranium isotopes | U-series dating | pedogenic carbonate | Marine Isotope Stage 4 D uring the last two glacial-interglacial cycles, North America experienced some of its most variable and dramatic changes in climate during recent Earth history. These climates were not only temporally dynamic but also, spatially nonuniform (1,2) in ways that are not yet completely clear. In part, this lack of clarity is because the most informative records-those that are long, continuous, and dated with millennial or better resolution-have been derived primarily from speleothems and/or lake sediments that are absent or rare in large regions of the continent.…”

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confidence: 99%

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Pedothem carbonates reveal anomalous North American atmospheric circulation 70,000–55,000 years ago

Oerter

Sharp

Oster

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Our understanding of climatic conditions, and therefore forcing factors, in North America during the past two glacial cycles is limited in part by the scarcity of long, well-dated, continuous paleoclimate records. Here, we present the first, to our knowledge, continuous, millennial-resolution paleoclimate proxy record derived from millimeter-thick pedogenic carbonate clast coatings (pedothems), which are widely distributed in semiarid to arid regions worldwide. Our new multiisotope pedothem record from the Wind River Basin in Wyoming confirms a previously hypothesized period of increased transport of Gulf of Mexico moisture northward into the continental interior from 70,000 to 55,000 years ago based on oxygen and carbon isotopes determined by ion microprobe and uranium isotopes and U-Th dating by laser ablation inductively coupled plasma mass spectrometry. This pronounced meridional moisture transport, which contrasts with the dominant zonal transport of Pacific moisture into the North American interior by westerly winds before and after 70,000–55,000 years ago, may have resulted from a persistent anticyclone developed above the North American ice sheet during Marine Isotope Stage 4. We conclude that pedothems, when analyzed using microanalytical techniques, can provide high-resolution paleoclimate records that may open new avenues into understanding past terrestrial climates in regions where paleoclimate records are not otherwise available. When pedothem paleoclimate records are combined with existing records they will add complimentary soil-based perspectives on paleoclimate conditions.

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Section: Atmospheric Circulation During and After The Last Glacial Mamentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Pedothem carbonates reveal anomalous North American atmospheric circulation 70,000–55,000 years ago

Oerter

Sharp

Oster

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Isotope-enabled GCMs have been used to simulate the geographic distribution of oxygen isotope values in precipitation (Carlson et al, 2008a;LeGrande et al, 2006;Pausata et al, 2011;Risi et al, 2010;Ullman et al, 2014;Werner et al, 2011;Yoshimura et al, 2008). Paleohydrologic records and modeling studies of North America from the LGM show that westerly storm tracks were shifted southward and intensified during the LGM (Oster et al, 2015, and references therein), and d 18 O records also indicate that precipitation was up to 7‰ more negative during glacial intervals . Variation in Greenland d 18 O values has also been attributed to southward shifts in storm tracks and moisture sources (Seierstad et al, 2014).…”

Section: Lis Melting Historymentioning

confidence: 99%

“…Oxygen isotope variations within an ice sheet are controlled by temperature, latitude, and altitude (Bowen and Wilkinson, 2002;Oerlemans, 1982), so the geochemical heterogeneity of the ice within an ice sheet preserves a record of physical parameters that affect Rayleigh fractionation, including ice-sheet elevation. During inception and growth of the LIS, southward deflection of westerly storm tracks over North America (Oster et al, 2015) may have had an effect on the isotopic value of precipitation over the LIS. The distribution of d 18 O values within an ice sheet is also dependent on ice flow subsequent to precipitation.…”

Section: Introductionmentioning

confidence: 99%

Oxygen isotope geochemistry of Laurentide ice-sheet meltwater across Termination I

Vetter

Spero

Eggins

et al. 2017

Quaternary Science Reviews

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a b s t r a c tWe present a new method that quantifies the oxygen isotope geochemistry of Laurentide ice-sheet (LIS) meltwater across the last deglaciation, and reconstruct decadal-scale variations in the d 18 O of LIS meltwater entering the Gulf of Mexico between~18 and 11 ka. We employ a technique that combines laser ablation ICP-MS (LA-ICP-MS) and oxygen isotope analyses on individual shells of the planktic values of Mississippi River discharge from discrete core intervals range from À22‰ to À38‰ VSMOW. These values suggest a dynamic melting history of different parts of the LIS, with potential contributions to Mississippi River outflow from both the low-elevation, southern margin of the LIS and high-elevation, high-latitude domes in the LIS interior that were transported to the ablation zone. Prior to~15.5 ka, the d 18 O water value of the Mississippi River was similar to that of regional precipitation or low-latitude LIS meltwater, but the Ba concentration in the Mississippi basin was affected by changes in weathering within the watershed, complicating Ba-salinity relationships in the Gulf of Mexico. After 13 ka, our data suggest Mississippi River outflow did not influence surface salinity above our Gulf of Mexico Orca Basin core site. Rather, we hypothesize that open ocean conditions prevailed as sea level rose and the paleoshoreline at the southern edge of North America retreated northward.

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Regional atmospheric circulation over Europe during the Last Glacial Maximum and its links to precipitation

et al. 2016

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The Last Glacial Maximum (LGM) exhibits different large‐scale atmospheric conditions compared to present‐day climate due to altered boundary conditions. The regional atmospheric circulation and associated precipitation patterns over Europe are characterized for the first time with a weather typing approach (circulation weather types, CWT) for LGM paleoclimate simulations. The CWT approach is applied to four representative regions across Europe. While the CWTs over Western Europe are prevailing westerly for both present‐day and LGM conditions, considerable differences are identified elsewhere: Southern Europe experienced more frequent westerly and cyclonic CWTs under LGM conditions, while Central and Eastern Europe was predominantly affected by southerly and easterly flow patterns. Under LGM conditions, rainfall is enhanced over Western Europe but is reduced over most of Central and Eastern Europe. These differences are explained by changing CWT frequencies and evaporation patterns over the North Atlantic Ocean. The regional differences of the CWTs and precipitation patterns are linked to the North Atlantic storm track, which was stronger over Europe in all considered models during the LGM, explaining the overall increase of the cyclonic CWT. Enhanced evaporation over the North Atlantic leads to higher moisture availability over the ocean. Despite the overall cooling during the LGM, this explains the enhanced precipitation over southwestern Europe, particularly Iberia. This study links large‐scale atmospheric dynamics to the regional circulation and associated precipitation patterns and provides an improved regional assessment of the European climate under LGM conditions.

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Steering of westerly storms over western North America at the Last Glacial Maximum

Cited by 202 publications

References 27 publications

Pedothem carbonates reveal anomalous North American atmospheric circulation 70,000–55,000 years ago

Pedothem carbonates reveal anomalous North American atmospheric circulation 70,000–55,000 years ago

Oxygen isotope geochemistry of Laurentide ice-sheet meltwater across Termination I

Regional atmospheric circulation over Europe during the Last Glacial Maximum and its links to precipitation

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