scholarly journals A Simple Model for the Anomalous Counterclockwise Turning of the Surface Wind with Time over the Great Plains of the United States

2018 ◽  
Vol 75 (9) ◽  
pp. 2971-2981
Author(s):  
Richard Rotunno ◽  
Glen S. Romine ◽  
Howard B. Bluestein
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Surface Layer ◽  
Simple Model ◽  
Analytical Model ◽  
Great Plains ◽  
Surface Wind ◽  
Forecast Model ◽  
The United States ◽  
Layer Effect

AbstractA recent study found that surface hodographs over the Great Plains of the United States turn in a counterclockwise direction with time. This observed turning is opposite of the clockwise turning observed (and expected, based on theory) at higher altitudes. Using a mesoscale forecast model, the same study shows that it has the same hodograph behavior as found in the observations. The study further shows that the reason for this anomalous counterclockwise turning is the decoupling of the surface layer from the boundary layer after sunset and its recoupling after sunrise. The present paper presents a simple model for this behavior by extending a recent analytical model for the diurnal oscillation to include the surface-layer effect. In addition, selected solution features are analyzed in terms of several of the nondimensional input parameters.

scholarly journals On the Anomalous Counterclockwise Turning of the Surface Wind with Time in the Plains of the United States

2018 ◽  
Vol 146 (2) ◽  
pp. 467-484 ◽  
Author(s):  
Howard B. Bluestein ◽  
Glen S. Romine ◽  
Richard Rotunno ◽  
Dylan W. Reif ◽  
Christopher C. Weiss
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Great Plains ◽  
Surface Wind ◽  
Vertical Mixing ◽  
The United States ◽  
Time Of Day ◽  
Boundary Layer Transition ◽  
Vertical Shear ◽  
Layer Transition

Vertical shear in the boundary layer affects the mode of convective storms that can exist if they are triggered. In western portions of the southern Great Plains of the United States, vertical shear, in the absence of any transient features, changes diurnally in a systematic way, thus leading to a preferred time of day for the more intense modes of convection when the shear, particularly at low levels, is greatest. In this study, yearly and seasonally averaged wind observations for each time of day are used to document the diurnal variations in wind at the surface and in the boundary layer, with synoptic and mesoscale features effectively filtered out. Data from surface mesonets in Oklahoma and Texas, Doppler wind profilers, instrumented tower data, and seasonally averaged wind data for each time of day from convection-allowing numerical model forecasts are used. It is shown through analysis of observations and model data that the perturbation wind above anemometer level turns in a clockwise manner with time, in a manner consistent with prior studies, yet the perturbation wind at anemometer level turns in an anomalous, counterclockwise manner with time. Evidence is presented based on diagnosis of the model forecasts that the dynamics during the early evening boundary layer transition are, in large part, responsible for the behavior of the hodographs at that time: as vertical mixing in the boundary layer diminishes, the drag on the wind at anemometer level persists, leading to rapid deceleration of the meridional component of the wind. This deceleration acts to turn the wind to the left rather than to the right, as would be expected from the Coriolis force alone.

scholarly journals Central and Eastern U.S. Surface Pressure Variations Derived from the USArray Network

2015 ◽  
Vol 143 (4) ◽  
pp. 1472-1493 ◽  
Author(s):  
Alexander A. Jacques ◽  
John D. Horel ◽  
Erik T. Crosman ◽  
Frank L. Vernon
Keyword(s):  
United States ◽  
Great Plains ◽  
Surface Pressure ◽  
Surface Wind ◽  
Pressure Sensors ◽  
Storm Track ◽  
The United States ◽  
Large Magnitude ◽  
Wide Range ◽  
Pressure Perturbations

Abstract Large-magnitude pressure signatures associated with a wide range of atmospheric phenomena (e.g., mesoscale gravity waves, convective complexes, tropical disturbances, and synoptic storm systems) are examined using a unique set of surface pressure sensors deployed as part of the National Science Foundation EarthScope USArray Transportable Array. As part of the USArray project, approximately 400 seismic stations were deployed in a pseudogrid fashion across a portion of the United States for 1–2 yr, then retrieved and redeployed farther east. Surface pressure observations at a sampling frequency of 1 Hz were examined during the period 1 January 2010–28 February 2014 when the seismic array was transitioning from the central to eastern continental United States. Surface pressure time series at over 900 locations were bandpass filtered to examine pressure perturbations on three temporal scales: meso- (10 min–4 h), subsynoptic (4–30 h), and synoptic (30 h–5 days) scales. Case studies of strong pressure perturbations are analyzed using web tools developed to visualize and track tens of thousands of such events with respect to archived radar imagery and surface wind observations. Seasonal assessments of the bandpass-filtered variance and frequency of large-magnitude events are conducted to identify prominent areas of activity. Large-magnitude mesoscale pressure perturbations occurred most frequently during spring in the southern Great Plains and shifted northward during summer. Synoptic-scale pressure perturbations are strongest during winter in the northern states with maxima located near the East Coast associated with frequent synoptic development along the coastal storm track.

scholarly journals Effects of Implementing MODIS Land Cover and Albedo in MM5 at Two Contrasting U.S. Regions

2006 ◽  
Vol 7 (5) ◽  
pp. 1043-1060 ◽  
Author(s):  
Ismail Yucel
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Land Cover ◽  
Planetary Boundary Layer ◽  
Land Surface ◽  
Surface Wind ◽  
The United States ◽  
Error Reduction ◽  
Near Surface ◽  
Temperature And Humidity

Abstract This study implements a new land-cover classification and surface albedo from the Moderate Resolution Imaging Spectroradiometer (MODIS) in the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) and investigates its effects on regional near-surface atmospheric state variables as well as the planetary boundary layer evolution for two dissimilar U.S. regions. Surface parameter datasets are determined by translating the 17-category MODIS classes into the U.S. Geological Survey (USGS) and Simple Biosphere (SiB) categories available for use in MM5. Changes in land-cover specification or associated parameters affected surface wind, temperature, and humidity fields, which, in turn, resulted in perceivable alterations in the evolving structure of the planetary boundary layer. Inclusion of the MODIS albedo into the simulations enhanced these impacts further. Area-averaged comparisons with ground measurements showed remarkable improvements in near-surface temperature and humidity at both study areas when MM5 is initialized with MODIS land-cover and albedo data. Influence of both MODIS surface datasets is more significant at a semiarid location in the southwest of the United States than it is in a humid location in the mid-Atlantic region. Intense summertime surface heating at the semiarid location creates favorable conditions for strong land surface forcing. For example, when the simulations include MODIS land cover and MODIS albedo, respective error reduction rates were 6% and 11% in temperature and 2% and 2.5% in humidity in the southwest of the United States. Error reduction rates in near-surface atmospheric fields are considered important in the design of mesoscale weather simulations.

Evidence of enhanced precipitation due to irrigation over the Great Plains of the United States

2010 ◽  
Vol 115 (D15) ◽  
Author(s):  
Anthony DeAngelis ◽  
Francina Dominguez ◽  
Ying Fan ◽  
Alan Robock ◽  
M. Deniz Kustu ◽  
...  
Keyword(s):  
United States ◽  
Great Plains ◽  
The United States

scholarly journals Spatial Disparities of COVID-19 Cases and Fatalities in United States Counties

2021 ◽  
Vol 18 (16) ◽  
pp. 8259
Author(s):  
Sarah L. Jackson ◽  
Sahar Derakhshan ◽  
Leah Blackwood ◽  
Logan Lee ◽  
Qian Huang ◽  
...  
Keyword(s):  
United States ◽  
Great Plains ◽  
Explanatory Power ◽  
Temporal Trends ◽  
The United States ◽  
First Year ◽  
Significant Case ◽  
Urban Rural ◽  
Spatial And Temporal Trends ◽  
Mitigation Policies

This paper examines the spatial and temporal trends in county-level COVID-19 cases and fatalities in the United States during the first year of the pandemic (January 2020–January 2021). Statistical and geospatial analyses highlight greater impacts in the Great Plains, Southwestern and Southern regions based on cases and fatalities per 100,000 population. Significant case and fatality spatial clusters were most prevalent between November 2020 and January 2021. Distinct urban–rural differences in COVID-19 experiences uncovered higher rural cases and fatalities per 100,000 population and fewer government mitigation actions enacted in rural counties. High levels of social vulnerability and the absence of mitigation policies were significantly associated with higher fatalities, while existing community resilience had more influential spatial explanatory power. Using differences in percentage unemployment changes between 2019 and 2020 as a proxy for pre-emergent recovery revealed urban counties were hit harder in the early months of the pandemic, corresponding with imposed government mitigation policies. This longitudinal, place-based study confirms some early urban–rural patterns initially observed in the pandemic, as well as the disparate COVID-19 experiences among socially vulnerable populations. The results are critical in identifying geographic disparities in COVID-19 exposures and outcomes and providing the evidentiary basis for targeting pandemic recovery.

scholarly journals Physiologic Specialization of Puccinia triticina on Wheat in the United States in 2013

Plant Disease ◽  
2015 ◽  
Vol 99 (9) ◽  
pp. 1261-1267 ◽  
Author(s):  
J. A. Kolmer ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Winter Wheat ◽  
Leaf Rust ◽  
Great Plains ◽  
Puccinia Triticina ◽  
The United States ◽  
Northern Great Plains ◽  
Ohio River ◽  
Ohio Valley ◽  
Red Winter Wheat

Collections of Puccinia triticina were obtained from rust-infected leaves provided by cooperators throughout the United States and from wheat fields and breeding plots by USDA-ARS personnel and cooperators in the Great Plains, Ohio River Valley, and southeastern states in order to determine the virulence of the wheat leaf rust population in 2013. Single uredinial isolates (490 total) were derived from the collections and tested for virulence phenotype on 20 lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes. In 2013, 79 virulence phenotypes were described in the United States. Virulence phenotypes MBTNB, TNBGJ, and MCTNB were the three most common phenotypes. Phenotypes MBTNB and MCTNB are both virulent to Lr11, and MCTNB is virulent to Lr26. MBTNB and MCTNB were most common in the soft red winter wheat region of the southeastern states and Ohio Valley. Phenotype TNBGJ is virulent to Lr39/41 and was widely distributed throughout the hard red winter wheat region of the Great Plains. Isolates with virulence to Lr11, Lr18, and Lr26 were common in the southeastern states and Ohio Valley region. Isolates with virulence to Lr21, Lr24, and Lr39/41 were frequent in the hard red wheat region of the southern and northern Great Plains.

scholarly journals Physiologic Specialization of Puccinia triticina on Wheat in the United States in 2005

Plant Disease ◽  
2007 ◽  
Vol 91 (8) ◽  
pp. 979-984 ◽  
Author(s):  
J. A. Kolmer ◽  
D. L. Long ◽  
M. E. Hughes
Keyword(s):  
United States ◽  
Leaf Rust ◽  
Great Plains ◽  
Durable Resistance ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
The United States ◽  
Ohio River ◽  
Virulence Phenotype ◽  
Common Phenotype

Collections of Puccinia triticina were obtained from rust-infected wheat leaves by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio River Valley, southeast, California, and Washington State, in order to determine the virulence of the wheat leaf rust population in 2005. Single uredinial isolates (797 in total) were derived from the collections and tested for virulence phenotype on lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes Lr1, Lr2a, Lr2c, Lr3a, Lr9, Lr16, Lr24, Lr26, Lr3ka, Lr11, Lr17a, Lr30, LrB, Lr10, Lr14a, Lr18, Lr21, Lr28, and winter wheat lines with genes Lr41 and Lr42. In the United States in 2005, 72 virulence phenotypes of P. triticina were found. Virulence phenotype TDBGH, selected by virulence to resistance gene Lr24, was the most common phenotype in the United States, and was found throughout the Great Plains region. Virulence phenotype MCDSB with virulence to Lr17a and Lr26 was the second most common phenotype and was found widely in the wheat growing regions of the United States. Virulence phenotype MFPSC, which has virulence to Lr17a, Lr24, and Lr26, was the third most common phenotype, and was found in the Ohio Valley region, the Great Plains, and California. The highly diverse population of P. triticina in the United States will continue to present a challenge for the development of wheat cultivars with effective durable resistance to leaf rust.

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