scholarly journals Dynamics, Variability, and Change in Seasonal Precipitation Reconstructions for North America

2020 ◽  
Vol 33 (8) ◽  
pp. 3173-3195 ◽  
Author(s):  
David W. Stahle ◽  
Edward R. Cook ◽  
Dorian J. Burnette ◽  
Max C. A. Torbenson ◽  
Ian M. Howard ◽  
...  
Keyword(s):  
United States ◽  
North America ◽  
Spatial Patterns ◽  
North American ◽  
Arctic Oscillation ◽  
Warm Season ◽  
The United States ◽  
The Arctic ◽  
Seasonal Precipitation ◽  
The Arctic Oscillation

AbstractCool- and warm-season precipitation totals have been reconstructed on a gridded basis for North America using 439 tree-ring chronologies correlated with December–April totals and 547 different chronologies correlated with May–July totals. These discrete seasonal chronologies are not significantly correlated with the alternate season; the December–April reconstructions are skillful over most of the southern and western United States and north-central Mexico, and the May–July estimates have skill over most of the United States, southwestern Canada, and northeastern Mexico. Both the strong continent-wide El Niño–Southern Oscillation (ENSO) signal embedded in the cool-season reconstructions and the Arctic Oscillation signal registered by the warm-season estimates faithfully reproduce the sign, intensity, and spatial patterns of these ocean–atmospheric influences on North American precipitation as recorded with instrumental data. The reconstructions are included in the North American Seasonal Precipitation Atlas (NASPA) and provide insight into decadal droughts and pluvials. They indicate that the sixteenth-century megadrought, the most severe and sustained North American drought of the past 500 years, was the combined result of three distinct seasonal droughts, each bearing unique spatial patterns potentially associated with seasonal forcing from ENSO, the Arctic Oscillation, and the Atlantic multidecadal oscillation. Significant 200–500-yr-long trends toward increased precipitation have been detected in the cool- and warm-season reconstructions for eastern North America. These seasonal precipitation changes appear to be part of the positive moisture trend measured in other paleoclimate proxies for the eastern area that began as a result of natural forcing before the industrial revolution and may have recently been enhanced by anthropogenic climate change.

A Remarkable Array: Species Diversity in the United States

2000 ◽  
Author(s):  
Bruce A. Stein ◽  
Larry E. Morse
Keyword(s):  
United States ◽  
North America ◽  
Sea Level ◽  
Eastern China ◽  
The United States ◽  
The Other ◽  
Death Valley ◽  
The Arctic ◽  
Blue Ridge Mountains ◽  
Little Tennessee River

The Carolina hemlock (Tsuga caroliniana) survives in just a few rocky streambeds along the lower slopes of the Blue Ridge Mountains. Other species of hemlock abound across the United States, but none bear a close resemblance to this particular tree. The closest relatives of the Carolina hemlock, in fact, survive in only one other forest on Earth, some 7,000 miles away in Hubei province of eastern China. The forests of eastern Asia and eastern North America are so similar that if you were suddenly transported from one to the other, you would be hard-pressed to tell them apart. In the swift mountain streams rushing past these seemingly displaced hemlocks live a number of small, colorful fish known as darters. Darters are found only in North America and have evolved into a prolific variety of fishes. Up to 175 species inhabit U.S. waters, including the famous snail darter (Percina tanasi), which brought endangered species issues to the fore when it held up construction of the Tellico Dam on the Little Tennessee River. How is it that these two organisms, hemlock and darter, one with its closest relatives on the other side of the globe and the other found nowhere else in the world, came to be living side by side? Just how many plants and animals share the piece of Earth that we know as the United States of America? Why these and not others? These are central questions for understanding the diversity of the nation’s living resources. The United States encompasses an enormous piece of geography. With more than 3.5 million square miles of land and 12,000 miles of coastline, it is the fourth largest country on Earth, surpassed only by Russia, Canada, and China. The nation spans nearly a third of the globe, extending more than 120 degrees of longitude from eastern Maine to the tip of the Aleutian chain, and 50 degrees in latitude from Point Barrow above the Arctic Circle to the southern tip of Hawaii below the tropic of Cancer. This expanse of terrain includes an exceptional variety of topographic features, from Death Valley at 282 feet below sea level to Mt. McKinley at 20,320 feet above sea level.

scholarly journals The North American Lightning Detection Network (NALDN)—Analysis of Flash Data: 2001–09

2011 ◽  
Vol 139 (5) ◽  
pp. 1305-1322 ◽  
Author(s):  
Richard E. Orville ◽  
Gary R. Huffines ◽  
William R. Burrows ◽  
Kenneth L. Cummins
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
The United States ◽  
The North ◽  
Lightning Detection ◽  
Geographical Regions ◽  
Positive Peak ◽  
The U.S ◽  
Cg Lightning

Cloud-to-ground (CG) lightning data have been analyzed for the years 2001–09 for North America, which includes Alaska, Canada, and the lower 48 U.S. states. Flashes recorded within the North American Lightning Detection Network (NALDN) are examined. No corrections for detection efficiency variability are made over the 9 yr of the dataset or over the large geographical area comprising North America. There were network changes in the NALDN during the 9 yr, but these changes have not been corrected for nor have the recorded data been altered in any way with the exception that all positive lightning reports with peak currents less than 15 kA have been deleted. Thus, the reader should be aware that secular changes are not just climatological in nature. All data were analyzed with a spatial resolution of 20 km. The analyses presented in this work provide a synoptic view of the interannual variability of lightning observations in North America, including the impacts of physical changes in the network during the 9 yr of study. These data complement and extend previous analyses that evaluate the U.S. NLDN during periods of upgrade. The total (negative and positive) flashes for ground flash density, the percentage of positive lightning, and the positive flash density have been analyzed. Furthermore, the negative and positive first stroke peak currents and the flash multiplicity have been examined. The highest flash densities in Canada are along the U.S.–Canadian border (1–2 flashes per square kilometer) and in the United States along the Gulf of Mexico coast from Texas through Florida (exceeding 14 flashes per square kilometer in Florida). The Gulf Stream is “outlined” by higher flash densities off the east coast of the United States. Maximum annual positive flash densities in Canada range primarily from 0.01 to 0.3 flashes per square kilometer, and in the United States to over 0.5 flashes per square kilometer in the Midwest and in the states of Louisiana and Mississippi. The annual percentage of positive lightning to ground varies from less than 2% over Florida to values exceeding 25% off the West Coast, Alaska, and the Yukon. A localized maximum in the percentage of positive lightning in the NALDN occurs in Manitoba and western Ontario, just north of North Dakota and Minnesota. When averaged over North America, first stroke negative median peak currents range from 19.8 kA in 2001 to 16.0 kA in 2009 and for all years, average 16.1 kA. First stroke positive median peak currents range from a high of 29.0 kA in 2008 and 2009 to a low of 23.3 kA in 2003 with a median of 25.7 kA for all years. There is a relatively sharp transition from low to high median negative peak currents along the Gulf and Atlantic coasts of the United States. No sharp transitions are observed for the median positive peak currents. Relatively lower positive peak currents occur throughout the southeastern United States. The highest values of mean negative multiplicity exceed 3.0 strokes per flash in the NALDN with some variation over the 9 yr. Lower values of mean negative multiplicity occur in the western United States. Positive flash mean multiplicity is slightly higher than 1.1, with the highest values of 1.7 observed in the southwestern states. As has been noted in prior research, CG lightning has significant variations from storm to storm as well as between geographical regions and/or seasons and, consequently, a single distribution for any lightning parameter, such as multiplicity or peak current, may not be sufficient to represent or describe the parameter.

Taxonomic studies on the genus Atrichum in North America

1969 ◽  
Vol 47 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Robert R. Ireland
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
Distinct Species ◽  
The United States ◽  
Morphological Characters ◽  
Taxonomic Study ◽  
Chromosome Counts ◽  
The Status ◽  
Taxonomic Studies

A taxonomic study was made of several North American taxa in the genus Atrichum. The primary emphasis was on the Canadian taxa and a key to the six species (A. altecristatum, A. angustatum, A. crispum, A. oerstedianum, A. selwynii, A. undulatum) and one variety (A. undulatum var. gracilisetum) of the country is presented. Atrichum oerstedianum, which has been confused with A. undulatum, is added to the moss flora of the United States and Canada. The distribution of A. crispum is clarified and a detailed study of the species revealed new morphological characters that are useful to distinguish it. A variety of A. undulatum, the var. altecristatum, is raised to the rank of a species and morphological and distributional data are given to support the status of A. selwynii as a distinct species. The first chromosome counts are reported for A. selwynii (n = 7) and A. altecristatum (n = 14). Detailed descriptions are provided for A. altecristatum, A. crispum, A. oerstedianum, and A. selwynii.

scholarly journals The enigma of the apparent disappearance of Eurasian highly pathogenic H5 clade 2.3.4.4 influenza A viruses in North American waterfowl

2016 ◽  
Vol 113 (32) ◽  
pp. 9033-9038 ◽  
Author(s):  
Scott Krauss ◽  
David E. Stallknecht ◽  
Richard D. Slemons ◽  
Andrew S. Bowman ◽  
Rebecca L. Poulson ◽  
...  
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
Influenza A ◽  
Wild Bird ◽  
Animal Health ◽  
The United States ◽  
Influenza Viruses ◽  
Influenza A Viruses ◽  
Highly Pathogenic

One of the major unresolved questions in influenza A virus (IAV) ecology is exemplified by the apparent disappearance of highly pathogenic (HP) H5N1, H5N2, and H5N8 (H5Nx) viruses containing the Eurasian hemagglutinin 2.3.4.4 clade from wild bird populations in North America. The introduction of Eurasian lineage HP H5 clade 2.3.4.4 H5N8 IAV and subsequent reassortment with low-pathogenic H?N2 and H?N1 North American wild bird-origin IAVs in late 2014 resulted in widespread HP H5Nx IAV infections and outbreaks in poultry and wild birds across two-thirds of North America starting in November 2014 and continuing through June 2015. Although the stamping out strategies adopted by the poultry industry and animal health authorities in Canada and the United States—which included culling, quarantining, increased biosecurity, and abstention from vaccine use—were successful in eradicating the HP H5Nx viruses from poultry, these activities do not explain the apparent disappearance of these viruses from migratory waterfowl. Here we examine current and historical aquatic bird IAV surveillance and outbreaks of HP H5Nx in poultry in the United States and Canada, providing additional evidence of unresolved mechanisms that restrict the emergence and perpetuation of HP avian influenza viruses in these natural reservoirs.

scholarly journals Common Ancestry of Borrelia burgdorferiSensu Lato Strains from North America and Europe

1999 ◽  
Vol 37 (9) ◽  
pp. 3010-3012 ◽  
Author(s):  
D. Postic ◽  
N. Marti Ras ◽  
R. S. Lane ◽  
P.-F. Humair ◽  
M. M. Wittenbrink ◽  
...  
Keyword(s):  
United States ◽  
North America ◽  
Borrelia Burgdorferi ◽  
North American ◽  
Phylogenetic Analyses ◽  
The United States ◽  
Whole Genome ◽  
Common Ancestry ◽  
Limited Region

Ten atypical European Borrelia burgdorferi sensu lato (Borrelia spp.) strains were genetically characterized, and the diversity was compared to that encountered among relatedBorrelia spp. from North America. Phylogenetic analyses of a limited region of the genome and of the whole genome extend existing knowledge about borrelial diversity reported earlier in Europe and the United States. Our results accord with the evidence that North American and European strains may have a common ancestry.

Muslims and Sexual Diversity in North America

2021 ◽  
Author(s):  
David Rayside
Keyword(s):  
United States ◽  
North America ◽  
North American ◽  
Religious Affiliation ◽  
Great Majority ◽  
The United States ◽  
Urban Environments ◽  
Sexual Diversity ◽  
Positive Attitudes ◽  
Muslim Communities

In many respects, the sizeable Muslim populations in the United States and Canada have integrated well into the social and political mainstream. Most of them are first-generation immigrants, and face Islamophobic prejudice based on race as well as religious affiliation. Still, they are a comparatively well-educated population, and identify strongly with the countries they now call home. Exploring the response of these communities to sexual diversity, and to growing claims for recognition by queer Muslims themselves, goes to the heart of questions about the place of this growing community in North American settings. This inevitably raises questions about gender relations within those communities, in part because discrimination against Muslims is often justified with reference to their adherence to what are thought to be unchanging patriarchal values. Doubts about social and cultural integration are easily intensified by the racialized “otherness” of Muslim populations in the West generally, and these two North American countries in particular. The Pew Research Center in the United States and the Environics Institute in Canada have conducted surveys of the Muslim populations in their countries, permitting a comparison of attitudes in those communities with those in the general population, and in some cases also providing a view of cross-country differences. What this polling reveals is that Muslims are on balance more politically progressive than non-Muslim populations, and are strongly averse to supporting conservative parties. However, it also reveals relatively negative views of homosexuality, and this is echoed in the public statements, or silence, of the largest Muslim advocacy groups. The strength of such views owes much to the fact that the majority of North American Muslims have emigrated from regions of the world where such opinions are deeply embedded in social and cultural life. Traditionalist views of gender and sexuality are also reinforced by high levels of religiosity, which in other faith currents is also associated with what might be called traditionalist views of family. In the case of Muslims, their religious leadership in Muslim communities remains almost unanimous in its condemnation of homosexuality as an example of “Western” permissiveness. Mosque life, too, retains important elements of gender inequity. There are, however, important indications of change, induced in part by the urban environments where the great majority of Muslims live, and the increasing willingness of queer Muslims to assert their presence within their ethno-religious communities as well as in lesbian, gay, bisexual, transgender, and queer (LGBTQ) networks. Younger Muslims are more inclined than their elders to hold inclusive attitudes, particularly if they have been educated in North America. In the United States, too, the latest of the Pew surveys has shown an important overall shift toward more LGBTQ-positive attitudes. This is in part a result of Muslims’ recognition that exclusionary attitudes on issues related to sexuality are often held by those who are also harbor Islamophobic views, and that policies designed to protect one community are also necessary to protect them.

Introduction

2020 ◽  
pp. 1-22
Author(s):  
Frank Towers
Keyword(s):  
United States ◽  
Nineteenth Century ◽  
North America ◽  
North American ◽  
The United States ◽  
Political Order ◽  
Nation State ◽  
History Of ◽  
Key Terms ◽  
The U.S

Today’s political map of North America took its basic shape in a continental crisis in the 1860s, marked by Canadian Confederation (1867), the end of the U.S. Civil War (1865), the restoration of the Mexican Republic (1867), and numerous wars and treaty regimes conducted between these states and indigenous peoples through the 1870s. This volume explores the tumultuous history of North American state-making in the mid-nineteenth century from a continental perspective that seeks to look across and beyond the traditional nation-centered approach. This introduction orients readers by first exploring the meaning of key terms—in particular sovereignty and its historical attachment to the concept of the nation state—and then previewing how contributors interrogate different themes of the mid-century struggles that remade the continent’s political order. Those themes fall into three main categories: the character of the states made and remade in the mid-1800s; the question of sovereignty for indigenous polities that confronted the European-settler descended governments of Canada, Mexico, and the United States; and the interaction between capitalist expansion and North American politics, and the concomitant implications of state making for sovereignty’s more diffuse meaning at the level of individual and group autonomy.

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