scholarly journals Tropopause-Penetrating Convection from Three-Dimensional Gridded NEXRAD Data

2016 ◽  
Vol 55 (2) ◽  
pp. 465-478 ◽  
Author(s):  
David L. Solomon ◽  
Kenneth P. Bowman ◽  
Cameron R. Homeyer
Keyword(s):  
United States ◽  
Three Dimensional ◽  
Warm Season ◽  
The United States ◽  
Lapse Rate ◽  
High Plains ◽  
Annual Cycles ◽  
Weather Radars ◽  
The North ◽  
The Stability

AbstractA new method that combines radar reflectivities from individual Next Generation Weather Radars (NEXRAD) into a three-dimensional composite with high horizontal and vertical resolution is used to estimate storm-top altitudes for the continental United States east of the Rocky Mountains. Echo-top altitudes are compared with the altitude of the lapse-rate tropopause calculated from the ERA-Interim reanalysis and radiosondes. To sample the diurnal and annual cycles, tropopause-penetrating convection is analyzed at 3-h intervals throughout 2004. Overshooting convection is most common in the north-central part of the United States (the high plains). There is a pronounced seasonal cycle; the majority of overshooting systems occur during the warm season (March–August). There is also a strong diurnal cycle, with maximum overshooting occurring near 0000 UTC. The overshooting volume decreases rapidly with height above the tropopause. Radiosonde observations are used to evaluate the quality of the reanalysis tropopause altitudes and the dependence of overshooting depth on environmental characteristics. The radar–radiosonde comparison reveals that overshooting is deeper in double-tropopause environments and increases as the stability of the lower stratosphere decreases.

scholarly journals A Radar-Based Climatology of Mesoscale Convective Systems in the United States

2019 ◽  
Vol 32 (5) ◽  
pp. 1591-1606 ◽  
Author(s):  
Alex M. Haberlie ◽  
Walker S. Ashley
Keyword(s):  
United States ◽  
Agricultural Land ◽  
Gulf Coast ◽  
Warm Season ◽  
The United States ◽  
Corn Belt ◽  
High Plains ◽  
Convective System ◽  
Aquifer Recharge ◽  
Mesoscale Convective

Abstract This research applies an automated mesoscale convective system (MCS) segmentation, classification, and tracking approach to composite radar reflectivity mosaic images that cover the contiguous United States (CONUS) and span a relatively long study period of 22 years (1996–2017). These data afford a novel assessment of the seasonal and interannual variability of MCSs. Additionally, hourly precipitation data from 16 of those years (2002–17) are used to systematically examine rainfall associated with radar-derived MCS events. The attributes and occurrence of MCSs that pass over portions of the CONUS east of the Continental Divide (ECONUS), as well as five author-defined subregions—North Plains, High Plains, Corn Belt, Northeast, and Mid-South—are also examined. The results illustrate two preferred regions for MCS activity in the ECONUS: 1) the Mid-South and Gulf Coast and 2) the Central Plains and Midwest. MCS occurrence and MCS rainfall display a marked seasonal cycle, with most of the regions experiencing these events primarily during the warm season (May–August). Additionally, MCS rainfall was responsible for over 50% of annual and seasonal rainfall for many locations in the ECONUS. Of particular importance, the majority of warm-season rainfall for regions with high agricultural land use (Corn Belt) and important aquifer recharge properties (High Plains) is attributable to MCSs. These results reaffirm that MCSs are a significant aspect of the ECONUS hydroclimate.

The sources of North Korean conduct: Is Pyongyang really going non-nuclear?

2020 ◽  
Vol 75 (2) ◽  
pp. 237-247
Author(s):  
Mun Suk Ahn
Keyword(s):  
United States ◽  
Economic Development ◽  
North Korea ◽  
The United States ◽  
Military Power ◽  
The North ◽  
The Stability

The Kim Jong Un regime recently shifted from an emphasis on military power to an ‘economy first’ policy. The shift was driven by a pragmatic calculation, on the part of the North Korean leader, recognizing that the stability of the regime depends on economic development. Kim hopes that a shift from nuclear confrontation to diplomacy will result in the lifting of Western sanctions. It is important that the United States interprets Kim’s intentions correctly, and tries to strike a deal with North Korea.

scholarly journals The Association of the Elevated Mixed Layer with Significant Severe Weather Events in the Northeastern United States*

2010 ◽  
Vol 25 (4) ◽  
pp. 1082-1102 ◽  
Author(s):  
Peter C. Banacos ◽  
Michael L. Ekster
Keyword(s):  
United States ◽  
Mixed Layer ◽  
Trajectory Analysis ◽  
Source Region ◽  
Warm Season ◽  
The United States ◽  
Severe Weather ◽  
Lapse Rate ◽  
Northeastern United States ◽  
Weather Events

Abstract The occurrence of rare but significant severe weather events associated with elevated mixed-layer (EML) air in the northeastern United States is investigated herein. A total of 447 convective event days with one or more significant severe weather report [where significant is defined as hail 2 in. (5.1 cm) in diameter or greater, a convective gust of 65 kt (33 m s−1) or greater, and/or a tornado of F2 or greater intensity] were identified from 1970 through 2006 during the warm season (1 May–30 September). Of these, 34 event days (7.6%) were associated with identifiable EML air in regional rawinsondes preceding the event. Taken with two other noteworthy events in 1953 and 1969, a total of 36 significant severe weather events associated with EML air were studied via composite and trajectory analysis. Though a small percentage of the total, these 36 events compose a noteworthy list of historically significant derechos and tornadic events to affect the northeastern United States. It is demonstrated that plumes of EML air emanating from the Intermountain West in subsiding, anticyclonically curved flows can reinforce the capping inversion and maintain the integrity of the EML across the central United States over a few days. The EML plume can ultimately become entrained into a moderately fast westerly to northwesterly midtropospheric flow allowing for the plume’s advection into the northeastern United States. Resultant thermodynamic conditions in the convective storm environment are similar to those more typically observed closer to the EML source region in the Great Plains of the United States. In addition to composite and trajectory analysis, two case studies are employed to demonstrate salient and evolutionary aspects of the EML in such events. A lapse rate tendency equation is explored to put EML advection in context with other processes affecting lapse rate.

scholarly journals On the Relationship between Spring NAO and Snowmelt in the Upper Southwestern United States

2017 ◽  
Vol 30 (14) ◽  
pp. 5141-5149 ◽  
Author(s):  
Boksoon Myoung ◽  
Seung Hee Kim ◽  
Jinwon Kim ◽  
Menas C. Kafatos
Keyword(s):  
United States ◽  
Southern Oscillation ◽  
Warm Season ◽  
Weather Conditions ◽  
Underlying Mechanism ◽  
The United States ◽  
The North ◽  
The North Atlantic Oscillation ◽  
The Relationship ◽  
Spring Snowmelt

This study examines the relationship between the North Atlantic Oscillation (NAO) and snowmelt in spring in the upper southwestern states of the United States (UP_SW) including California, Nevada, Utah, and Colorado, using SNOTEL datasets for 34 yr (1980–2014). Statistically significant negative correlations are found between NAO averages in the snowmelt period and timings of snowmelt (i.e., positive NAO phases in spring enhance snowmelt, and vice versa). It is also found that correlations between El Niño–Southern Oscillation and snowmelt are negligible in the region. The NAO–snowmelt relationship is most pronounced below the 2800-m level; above this level, the relationship becomes weaker. The underlying mechanism for this link is that a positioning of upper-tropospheric anticyclonic (cyclonic) circulations over the western United States that are associated with development of the positive (negative) NAO phases tends to bring warmer and drier (colder and wetter) spring weather conditions to the region. The temperature variations related with the NAO phases also strongly modulate the snowfall–rainfall partitioning. The relationship between the NAO and spring snowmelt can serve as key information for the warm season water resources management in the UP_SW.

The Making of a University Professor, USA—1936–84

PMLA ◽  
1994 ◽  
Vol 109 (5) ◽  
pp. 935-940
Author(s):  
Germaine Brée
Keyword(s):  
United States ◽  
American Academy ◽  
North American ◽  
The United States ◽  
The North ◽  
University Professor ◽  
The Stability

Thinking back on my life in the precincts of the North American academy, I am struck by the variety it offered within a constant and recognizable ambience that I think of as distinctly American. I have lived and worked in the United States for half a century and feel grateful for both the unforeseen paths it opened for me and the stability it provided.

scholarly journals GOES Climatology and Analysis of Thunderstorms with Enhanced 3.9-μm Reflectivity

2006 ◽  
Vol 134 (9) ◽  
pp. 2342-2353 ◽  
Author(s):  
Daniel T. Lindsey ◽  
Donald W. Hillger ◽  
Louie Grasso ◽  
John A. Knaff ◽  
John F. Dostalek
Keyword(s):  
United States ◽  
Rocky Mountain ◽  
The United States ◽  
Vertical Shear ◽  
High Plains ◽  
Eastern United States ◽  
Ice Crystal ◽  
Reanalysis Dataset ◽  
The North ◽  
Ice Crystal Size

Abstract By combining observations from the Geostationary Operational Environmental Satellite (GOES) 3.9- and 10.7-μm channels, the reflected component of the 3.9-μm radiance can be isolated. In this paper, these 3.9-μm reflectivity measurements of thunderstorm tops are studied in terms of their climatological values and their utility in diagnosing cloud-top microphysical structure. These measurements provide information about internal thunderstorm processes, including updraft strength, and may be useful for severe weather nowcasting. Three years of summertime thunderstorm-top 3.9-μm reflectivity values are analyzed to produce maps of climatological means across the United States. Maxima occur in the high plains and Rocky Mountain regions, while lower values are observed over much of the eastern United States. A simple model is used to establish a relationship between 3.9-μm reflectivity and ice crystal size at cloud top. As the mean diameter of a cloud-top ice crystal distribution decreases, more solar radiation near 3.9 μm is reflected. Using the North American Regional Reanalysis dataset, the thermodynamic environment that favors thunderstorms with large 3.9-μm reflectivity values is identified. In the high plains and mountains, environments with relatively dry boundary layers, steep lapse rates, and large vertical shear values favor thunderstorms with enhanced 3.9-μm reflectivity. Thunderstorm processes that lead to small ice crystals at cloud top are discussed, and a possible relationship between updraft strength and 3.9-μm reflectivity is presented.

Mafias on the Move

2011 ◽  
Author(s):  
Federico Varese
Keyword(s):  
United States ◽  
New York ◽  
Organized Crime ◽  
The United States ◽  
The West ◽  
Market Expansion ◽  
The North ◽  
Economic Transformations ◽  
At Will

Organized crime is spreading like a global virus as mobs take advantage of open borders to establish local franchises at will. That at least is the fear, inspired by stories of Russian mobsters in New York, Chinese triads in London, and Italian mafias throughout the West. As this book explains, the truth is more complicated. The author has spent years researching mafia groups in Italy, Russia, the United States, and China, and argues that mafiosi often find themselves abroad against their will, rather than through a strategic plan to colonize new territories. Once there, they do not always succeed in establishing themselves. The book spells out the conditions that lead to their long-term success, namely sudden market expansion that is neither exploited by local rivals nor blocked by authorities. Ultimately the inability of the state to govern economic transformations gives mafias their opportunity. In a series of matched comparisons, the book charts the attempts of the Calabrese 'Ndrangheta to move to the north of Italy, and shows how the Sicilian mafia expanded to early twentieth-century New York, but failed around the same time to find a niche in Argentina. The book explains why the Russian mafia failed to penetrate Rome but succeeded in Hungary. A pioneering chapter on China examines the challenges that triads from Taiwan and Hong Kong find in branching out to the mainland. This book is both a compelling read and a sober assessment of the risks posed by globalization and immigration for the spread of mafias.

scholarly journals “The Future of Archaeology Is Antiracist”: Archaeology in the Time of Black Lives Matter

2021 ◽  
pp. 1-20
Author(s):  
Ayana Omilade Flewellen ◽  
Justin P. Dunnavant ◽  
Alicia Odewale ◽  
Alexandra Jones ◽  
Tsione Wolde-Michael ◽  
...  
Keyword(s):  
United States ◽  
North American ◽  
The United States ◽  
Heritage Preservation ◽  
Social Unrest ◽  
Black Lives Matter ◽  
The North ◽  
Road Map ◽  
The Social ◽  
The Future

This forum builds on the discussion stimulated during an online salon in which the authors participated on June 25, 2020, entitled “Archaeology in the Time of Black Lives Matter,” and which was cosponsored by the Society of Black Archaeologists (SBA), the North American Theoretical Archaeology Group (TAG), and the Columbia Center for Archaeology. The online salon reflected on the social unrest that gripped the United States in the spring of 2020, gauged the history and conditions leading up to it, and considered its rippling throughout the disciplines of archaeology and heritage preservation. Within the forum, the authors go beyond reporting the generative conversation that took place in June by presenting a road map for an antiracist archaeology in which antiblackness is dismantled.

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