scholarly journals Madden–Julian Oscillation–Induced Suppression of Northeast Pacific Convection Increases U.S. Tornadogenesis

2020 ◽  
Vol 33 (11) ◽  
pp. 4927-4939 ◽  
Author(s):  
Dongmin Kim ◽  
Sang-Ki Lee ◽  
Hosmay Lopez
Keyword(s):  
United States ◽  
Large Scale ◽  
Diabatic Heating ◽  
Convective Available Potential Energy ◽  
The United States ◽  
Madden Julian Oscillation ◽  
Atmospheric Conditions ◽  
Low Level ◽  
Northeast Pacific ◽  
The Impact

AbstractThis study investigates the impact of the Madden–Julian oscillation (MJO) on U.S. tornadogenesis using atmospheric reanalysis and model experiments. Our analysis shows that the impact of MJO on U.S. tornadogenesis is most significant in May–July and during MJO phases 3–4 and 5–6 (P3456). These MJO phases are characterized by anomalous ascending motion over the Maritime Continent (MC) and anomalous subsidence over the northeast Pacific (EP), generating anomalous diabatic heating and cooling, respectively. These in turn generate large-scale atmospheric conditions conducive to tornadogenesis in the United States, enhancing the North American low-level jet (NALLJ) and thus increasing the influx of warm and moist air from the Gulf of Mexico to the United States and increasing the low-level wind shear and convective available potential energy along its path. Conversely, during MJO phases 1–2 and 7–8, the opposite patterns of atmospheric anomalies appear over the United States producing unfavorable environments for U.S. tornadogenesis. We further investigate the underlying mechanism for MJO-induced atmospheric circulations conducive to U.S. tornadogenesis using a linear baroclinic model (LBM). The LBM is forced by diabatic heating over the MC and cooling over the EP, which characterizes the P3456 MJO phase. The model experiment reproduces an anomalous ridge over the southern United States and associated anomalous low-level anticyclone that enhances the NALLJ and increases tornadic environmental parameters. Additional sensitivity experiments prescribing the diabatic heating over the MC and diabatic cooling over the EP independently demonstrate that diabatic cooling over the EP is the main driver for producing regional atmospheric conditions favorable for U.S. tornadogenesis.

scholarly journals Climatology of Severe Local Storm Environments and Synoptic-Scale Features over North America in ERA5 Reanalysis and CAM6 Simulation

2020 ◽  
Vol 33 (19) ◽  
pp. 8339-8365 ◽  
Author(s):  
Funing Li ◽  
Daniel R. Chavas ◽  
Kevin A. Reed ◽  
Daniel T. Dawson II
Keyword(s):  
United States ◽  
North America ◽  
Great Plains ◽  
Large Scale ◽  
Extreme Values ◽  
Convective Available Potential Energy ◽  
The United States ◽  
Synoptic Scale ◽  
Low Level ◽  
High Bias

AbstractSevere local storm (SLS) activity is known to occur within specific thermodynamic and kinematic environments. These environments are commonly associated with key synoptic-scale features—including southerly Great Plains low-level jets, drylines, elevated mixed layers, and extratropical cyclones—that link the large-scale climate to SLS environments. This work analyzes spatiotemporal distributions of both extreme values of SLS environmental parameters and synoptic-scale features in the ERA5 reanalysis and in the Community Atmosphere Model, version 6 (CAM6), historical simulation during 1980–2014 over North America. Compared to radiosondes, ERA5 successfully reproduces SLS environments, with strong spatiotemporal correlations and low biases, especially over the Great Plains. Both ERA5 and CAM6 reproduce the climatology of SLS environments over the central United States as well as its strong seasonal and diurnal cycles. ERA5 and CAM6 also reproduce the climatological occurrence of the synoptic-scale features, with the distribution pattern similar to that of SLS environments. Compared to ERA5, CAM6 exhibits a high bias in convective available potential energy over the eastern United States primarily due to a high bias in surface moisture and, to a lesser extent, storm-relative helicity due to enhanced low-level winds. Composite analysis indicates consistent synoptic anomaly patterns favorable for significant SLS environments over much of the eastern half of the United States in both ERA5 and CAM6, though the pattern differs for the southeastern United States. Overall, our results indicate that both ERA5 and CAM6 are capable of reproducing SLS environments as well as the synoptic-scale features and transient events that generate them.

Situational Breakdowns

2019 ◽  
Author(s):  
Anne Nassauer
Keyword(s):  
United States ◽  
Large Scale ◽  
Contextual Factors ◽  
The United States ◽  
Social Outcomes ◽  
Dynamic Processes ◽  
Collective Decisions ◽  
Different Types ◽  
The Impact

This book provides an account of how and why routine interactions break down and how such situational breakdowns lead to protest violence and other types of surprising social outcomes. It takes a close-up look at the dynamic processes of how situations unfold and compares their role to that of motivations, strategies, and other contextual factors. The book discusses factors that can draw us into violent situations and describes how and why we make uncommon individual and collective decisions. Covering different types of surprise outcomes from protest marches and uprisings turning violent to robbers failing to rob a store at gunpoint, it shows how unfolding situations can override our motivations and strategies and how emotions and culture, as well as rational thinking, still play a part in these events. The first chapters study protest violence in Germany and the United States from 1960 until 2010, taking a detailed look at what happens between the start of a protest and the eruption of violence or its peaceful conclusion. They compare the impact of such dynamics to the role of police strategies and culture, protesters’ claims and violent motivations, the black bloc and agents provocateurs. The analysis shows how violence is triggered, what determines its intensity, and which measures can avoid its outbreak. The book explores whether we find similar situational patterns leading to surprising outcomes in other types of small- and large-scale events: uprisings turning violent, such as Ferguson in 2014 and Baltimore in 2015, and failed armed store robberies.

scholarly journals Impact of the first COVID-19 shelter-in-place order in the United States on emergency department utilization, Marin County, California

2020 ◽  
Author(s):  
Brett R. Bayles ◽  
Michaela F George ◽  
Haylea Hannah ◽  
Patti Culross ◽  
Rochelle R. Ereman ◽  
...  
Keyword(s):  
United States ◽  
San Francisco ◽  
Large Scale ◽  
Temporal Dynamics ◽  
The United States ◽  
Emergency Department Utilization ◽  
Marin County ◽  
Before And After ◽  
Ed Visits ◽  
The Impact

Background: The first shelter-in-place (SIP) order in the United States was issued across six counties in the San Francisco Bay Area to reduce the impact of COVID-19 on critical care resources. We sought to assess the impact of this large-scale intervention on emergency departments (ED) in Marin County, California. Methods: We conducted a retrospective descriptive and trend analysis of all ED visits in Marin County, California from January 1, 2018 to May 4, 2020 to quantify the temporal dynamics of ED utilization before and after the March 17, 2020 SIP order. Results: The average number of ED visits per day decreased by 52.3% following the SIP order compared to corresponding time periods in 2018 and 2019. Both respiratory and non-respiratory visits declined, but this negative trend was most pronounced for non-respiratory admissions. Conclusions: The first SIP order to be issued in the United States in response to COVID-19 was associated with a significant reduction in ED utilization in Marin County.

Assessing the Impact of Remittances on Schooling: the Mexican Experience

2005 ◽  
Vol 5 (1) ◽  
pp. 1850033 ◽  
Author(s):  
Fernando Borraz
Keyword(s):  
United States ◽  
Human Capital ◽  
Census Data ◽  
The United States ◽  
Level Of Education ◽  
Low Level ◽  
Child Human Capital ◽  
The Impact

This paper analyzes the impact of remittances on child human capital in Mexico. During the 90’s and in particular after the “tequila crisis” Mexican workers increased the remittances that were sent to their homes from the United States. I will analyze the effect of such increasing source of income on child human capital decisions. Contrary to Hanson and Woodruff (2003) the results obtained from Census data indicate a positive and small effect of remittances on schooling only for children living in cities with fewer than 2,500 inhabitants and with mothers with a very low level of education. However its magnitude is not substantial.

scholarly journals Role of Soil Moisture Feedback in the Development of Extreme Summer Drought and Flood in the United States

2016 ◽  
Vol 17 (8) ◽  
pp. 2191-2207 ◽  
Author(s):  
Roop Saini ◽  
Guiling Wang ◽  
Jeremy S. Pal
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Large Scale ◽  
Climate Model ◽  
The United States ◽  
Summer Drought ◽  
Large Set ◽  
Drought And Flood ◽  
The Impact ◽  
Soil Moisture Feedback

Abstract This study tackles the contribution of soil moisture feedback to the development of extreme summer precipitation anomalies over the conterminous United States using a regional climate model. The model performs well in reproducing both the mean climate and extremes associated with drought and flood. A large set of experiments using the model are conducted that involve swapped initial soil moisture between flood and drought years using the 1988 and 2012 droughts and 1993 flood as examples. The starting time of these experiments includes 1 May (late spring) and 1 June (early summer). For all three years, the impact of 1 May soil moisture swapping is much weaker than the 1 June soil moisture swapping. In 1988 and 2012, replacing the 1 June soil moisture with that from 1993 reduces both the spatial extent and the severity of the simulated summer drought and heat. The impact is especially strong in 2012. In 1993, however, replacing the 1 June soil moisture with that from 1988 has little impact on precipitation. The contribution of soil moisture feedback to summer extremes is larger in 2012 than in 1988 and 1993. This may be because of the presence of strong anomalies in large-scale forcing in 1988 and 1993 that prohibit or favor precipitation, and the lack of such in 2012. This study demonstrates how the contribution of land–atmosphere feedback to the development of seasonal climate anomalies may vary from year to year and highlights its importance in the 2012 drought.

scholarly journals Cultures of light: Electric light in the United States, 1890s-1950s

2021 ◽  
Author(s):  
◽  
Margaret Maile Petty
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Large Scale ◽  
Cultural Beliefs ◽  
The United States ◽  
Light Industry ◽  
Electric Light ◽  
American Society ◽  
The Individual ◽  
The Impact

<p>Cultures of Light is set within a period that stretches from the late nineteenth to the mid-twentieth century in the United States, an era in which nearly every aspect of American life was impacted to a lesser or greater degree by the introduction, distribution and integration of electric power and light. By no means attempting to comprehensively examine the impact and effects of this expansive transformation, this thesis has a narrow but meaningful target, defined by key intersections of electric lighting and American culture. Primarily concerned with the investigation of culturally bound ideas and practices as mediated through electric light and its applications, my thesis is focused on particular instances of this interplay. These include its role in supporting nationalizing narratives and agendas through large-scale demonstrations at world’s fairs and exhibitions, in the search for and expression of modernism and its variations in the United States. Similarly electricity and electric light throughout the better part of the twentieth century was scaled to the level of the individual through a number of mechanisms and narratives. Most prominently the electric light industry employed gendered discourses, practices and beliefs in their efforts to grow the market, calling upon the assistance of a host of cultural influencers, from movie stars to architects to interior designers, instigating a renegotiation of established approaches to the design of architecture and the visual environment. Connecting common themes and persistent concerns across these seemingly disparate subject areas through the examination of cultural beliefs, practices, rituals and traditions, Cultures of Light seeks to illustrate the deep and lasting significance of electric light within American society in the twentieth century.</p>

scholarly journals An Analogue Approach to Identify Heavy Precipitation Events: Evaluation and Application to CMIP5 Climate Models in the United States

2014 ◽  
Vol 27 (15) ◽  
pp. 5941-5963 ◽  
Author(s):  
Xiang Gao ◽  
C. Adam Schlosser ◽  
Pingping Xie ◽  
Erwan Monier ◽  
Dara Entekhabi
Keyword(s):  
United States ◽  
Large Scale ◽  
Heavy Precipitation ◽  
The United States ◽  
Cmip5 Models ◽  
Atmospheric Conditions ◽  
South Central ◽  
Simulated Precipitation ◽  
Analogue Method ◽  
Precipitation Events

Abstract An analogue method is presented to detect the occurrence of heavy precipitation events without relying on modeled precipitation. The approach is based on using composites to identify distinct large-scale atmospheric conditions associated with widespread heavy precipitation events across local scales. These composites, exemplified in the south-central, midwestern, and western United States, are derived through the analysis of 27-yr (1979–2005) Climate Prediction Center (CPC) gridded station data and the NASA Modern-Era Retrospective Analysis for Research and Applications (MERRA). Circulation features and moisture plumes associated with heavy precipitation events are examined. The analogues are evaluated against the relevant daily meteorological fields from the MERRA reanalysis and achieve a success rate of around 80% in detecting observed heavy events within one or two days. The method also captures the observed interannual variations of seasonal heavy events with higher correlation and smaller RMSE than MERRA precipitation. When applied to the same 27-yr twentieth-century climate model simulations from Phase 5 of the Coupled Model Intercomparison Project (CMIP5), the analogue method produces a more consistent and less uncertain number of seasonal heavy precipitation events with observation as opposed to using model-simulated precipitation. The analogue method also performs better than model-based precipitation in characterizing the statistics (minimum, lower and upper quartile, median, and maximum) of year-to-year seasonal heavy precipitation days. These results indicate the capability of CMIP5 models to realistically simulate large-scale atmospheric conditions associated with widespread local-scale heavy precipitation events with a credible frequency. Overall, the presented analyses highlight the improved diagnoses of the analogue method against an evaluation that considers modeled precipitation alone to assess heavy precipitation frequency.

Firm Size and Industrial Structure in the United States During the Nineteenth Century

1986 ◽  
Vol 46 (2) ◽  
pp. 463-475 ◽  
Author(s):  
Jeremy Atack
Keyword(s):  
United States ◽  
Nineteenth Century ◽  
Size Distribution ◽  
Firm Size ◽  
Large Scale ◽  
Industrial Structure ◽  
The United States ◽  
Clear Trend ◽  
Economic Concentration ◽  
The Impact

This paper investigates the impact of the emergence of large-scale enterprises on industrial structure in America in the mid-nineteenth century and concludes that their impact was ambiguous. In cottons and irons, average scale increased dramatically, but inequality in the size distribution of plants declined and economic concentration showed no clear trend. In other industries, changes in average scale were much smaller and inequality increased, but again there was no clear trend in concentration.

scholarly journals Strong Surface Fronts over Sloping Terrain and Coastal Plains

2008 ◽  
Vol 55 ◽  
pp. 35-86 ◽  
Author(s):  
Lance F. Bosart ◽  
Alicia C. Wasula ◽  
Walter H. Drag ◽  
Keith W. Meier
Keyword(s):  
New England ◽  
Large Scale ◽  
Diabatic Heating ◽  
The United States ◽  
Entrance Region ◽  
The Arctic ◽  
Upper Level ◽  
Sloping Terrain ◽  
Low Amplitude ◽  
The Impact

Abstract This paper begins with a review of basic surface frontogenesis concepts with an emphasis on fronts located over sloping terrain adjacent to mountain barriers and fronts located in large-scale baroclinic zones close to coastlines. The impact of cold-air damming and differential diabatic heating and cooling on frontogenesis is considered through two detailed case studies of intense surface fronts. The first case, from 17 to 18 April 2002, featured the westward passage of a cold (side-door) front across coastal eastern New England in which 15°–20°C temperature decreases were observed in less than one hour. The second case, from 28 February to 4 March 1972, featured a long-lived front that affected most of the United States from the Rockies to the Atlantic coast and was noteworthy for a 50°C temperature contrast between Kansas and southern Manitoba, Canada. In the April 2002 case most of New England was initially covered by an unusually warm, dry air mass. Dynamical anticyclogenesis over eastern Canada set the stage for a favorable pressure gradient to allow chilly marine air to approach coastal New England from the east. Diabatic cooling over the chilly (5°–8°C) waters of the Gulf of Maine allowed surface pressures to remain relatively high offshore while diabatic heating over the land (31°–33°C temperatures) enabled surface pressures to fall relative to over the ocean. The resulting higher pressures offshore resulted in an onshore cold push. Frontal intensity was likely enhanced prior to leaf out and grass green-up as virtually all of the available insolation went into sensible heating. The large-scale environment in the February–March 1972 case favored the accumulation of bitterly cold arctic air in Canada. Frontal formation occurred over northern Montana and North Dakota as the arctic air moved slowly southward in conjunction with surface pressure rises east of the Canadian Rockies. The arctic air accelerated southward subsequent to lee cyclogenesis–induced pressure falls ahead of an upstream trough that crossed the Rockies. The southward acceleration of the arctic air was also facilitated by dynamic anticyclogenesis in southern Canada beneath a poleward jet-entrance region. Frontal intensity varied diurnally in response to differential diabatic heating. Three types of cyclogenesis events were observed over the lifetime of the event: 1) low-amplitude frontal waves with no upper-level support, 2) low-amplitude frontal waves that formed in a jet-entrance region, and 3) cyclones that formed ahead of advancing upper-level troughs. All cyclones were either nondeveloping or weak developments despite extreme baroclinicity, likely the result of large atmospheric static stability in the arctic frontal zone and unfavorable alongfront stretching deformation. Significant frontal–mountain interactions were observed over the Rockies and the Appalachians.

Sign in / Sign up

Export Citation Format

Share Document