scholarly journals The Heated Condensation Framework. Part II: Climatological Behavior of Convective Initiation and Land–Atmosphere Coupling over the Conterminous United States

2015 ◽  
Vol 16 (5) ◽  
pp. 1946-1961 ◽  
Author(s):  
Ahmed B. Tawfik ◽  
Paul A. Dirmeyer ◽  
Joseph A. Santanello
Keyword(s):  
United States ◽  
Great Plains ◽  
Potential Temperature ◽  
The United States ◽  
Convective Initiation ◽  
Positive Feedbacks ◽  
Southern Great Plains ◽  
The North ◽  
Wrong Reason ◽  
Energy Advantage

Abstract This is Part II of a two-part study introducing the heated condensation framework (HCF), which quantifies the potential convective state of the atmosphere in terms of land–atmosphere interactions. Part I introduced the full suite of HCF variables and applied them to case studies with observations and models over a single location in the southern Great Plains. It was shown in Part I that the HCF was capable of identifying locally initiated convection and quantifying energetically favorable pathways for initiation. Here, the HCF is applied to the entire conterminous United States and the climatology of convective initiation (CI) in relation to local land–atmosphere coupling (LoCo) is explored for 34 summers (June–August) using the North American Regional Reanalysis (NARR) and observations. NARR is found to be capable of capturing the convective threshold (buoyant mixing potential temperature θBM) and energy advantage transition (energy advantage potential temperature θadv) for most of the United States. However, there are compensating biases in the components of moisture qmix and temperature q*, resulting in low θBM biases for the wrong reason. The HCF has been used to show that local CI occurred over the Rocky Mountains and the southern Great Plains 35%–65% of the time. Finally, the LoCo process chain has been recast in light of the HCF. Both positive and negative soil moisture–convective feedbacks are possible, with negative feedbacks producing a stronger response in CI likelihood under weak convective inhibition. Positive feedbacks are present but weaker.

scholarly journals Primary Atmospheric Drivers of Pluvial Years in the United States Great Plains

2018 ◽  
Vol 19 (4) ◽  
pp. 643-658 ◽  
Author(s):  
Paul X. Flanagan ◽  
Jeffrey B. Basara ◽  
Jason C. Furtado ◽  
Xiangming Xiao
Keyword(s):  
United States ◽  
Great Plains ◽  
Heavy Precipitation ◽  
The United States ◽  
Precipitation Variability ◽  
Northern Great Plains ◽  
Southern Great Plains ◽  
The Public ◽  
Moisture Fluxes ◽  
Precipitation Events

Abstract Precipitation variability has increased in recent decades across the Great Plains (GP) of the United States. Drought and its associated drivers have been studied in the GP region; however, periods of excessive precipitation (pluvials) at seasonal to interannual scales have received less attention. This study narrows this knowledge gap with the overall goal of understanding GP precipitation variability during pluvial periods. Through composites of relevant atmospheric variables from the ECMWF twentieth-century reanalysis (ERA-20C), key differences between southern Great Plains (SGP) and northern Great Plains (NGP) pluvial periods are highlighted. The SGP pluvial pattern shows an area of negative height anomalies over the southwestern United States with wind anomalies consistent with frequent synoptic wave passages along a southward-shifted North Pacific jet. The NGP pattern during pluvial periods, by contrast, depicts anomalously low heights in the northwestern United States and an anomalously extended Pacific jet. Analysis of daily heavy precipitation events reveals the key drivers for these pluvial events, namely, an east–west height gradient and associated stronger poleward moisture fluxes. Therefore, the results show that pluvial years over the GP are likely driven by synoptic-scale processes rather than by anomalous seasonal precipitation driven by longer time-scale features. Overall, the results present a possible pathway to predicting the occurrence of pluvial years over the GP and understanding the causes of GP precipitation variability, potentially mitigating the threats of water scarcity and excesses for the public and agricultural sectors.

scholarly journals Cold Climate Winegrape Cultivar Sensitivity to Sulfur in the Northern Great Plains Region of the United States

2017 ◽  
Vol 27 (2) ◽  
pp. 235-239
Author(s):  
Nagehan D. Köycü ◽  
John E. Stenger ◽  
Harlene M. Hatterman-Valenti
Keyword(s):  
United States ◽  
Great Plains ◽  
The United States ◽  
Organic Production ◽  
Cold Climate ◽  
Future Research ◽  
Northern Great Plains ◽  
Research Station ◽  
Injury Incidence ◽  
The North

Elemental sulfur is commonly applied for powdery mildew (Erysiphe necator) protection on winegrape (Vitis sp.). The product may be used in a diversified, integrated disease management system to help prevent fungicide resistance to products with other modes of action. Additionally, sulfur may be used as a control option in organic systems. Applications of sulfur have been known to cause phytotoxic injury to susceptible winegrape cultivars, particularly those stemming from fox grape (Vitis labrusca) parentage. To improve recommendations to producers in the northern Great Plains region of the United States, a comparison of injury incidence and severity, as well as effects on yield characteristics was undertaken for 13 regional cultivars exposed to three sulfur rates (0, 2.4, and 4.8 lb/acre a.i.) at a North Dakota State University Research Station near Absaraka, ND. Overall, four cultivars (Bluebell, Baltica, Sabrevois, and King of the North) of the 13 cultivars tested showed phytotoxic symptoms. Injury severity and incidence of these cultivars differed between years and across rates. ‘Bluebell’ showed consistent and severe sulfur injury symptoms. Injury to the other three susceptible cultivars tended to vary by the given environment, with King of the North generally showing the lowest injury response. Injury symptoms were not found to be associated with the overall yield or cluster weight. Results suggest that alternative spray programs that exclude sulfur-based fungicides should be recommended for ‘Bluebell’, ‘Baltica’, ‘Sabrevois’, and ‘King of the North’, whereas sulfur-based fungicides may be applied to ‘Alpenglow’, ‘ES 12-6-18’, ‘Frontenac’, ‘Frontenac Gris’, ‘La Crescent’, ‘Marquette’, ‘Somerset Seedless’, ‘St. Croix’, and ‘Valiant’. Observations on fruit ripening in 2014 suggest that future research is needed to determine if a reduction of fruit quality may occur in some seasons with repeated sulfur applications or with successive annual sulfur applications for susceptible cultivars if used in an organic production system.

CRUSTAL ELECTRICAL CONDUCTIVITY ANOMALIES IN THE GREAT PLAINS PROVINCE OF THE UNITED STATES

Geophysics ◽  
1971 ◽  
Vol 36 (2) ◽  
pp. 382-395 ◽  
Author(s):  
H. Porath ◽  
A. Dziewonski
Keyword(s):  
United States ◽  
Electrical Conductivity ◽  
Great Plains ◽  
Gulf Coast ◽  
Small Variation ◽  
The United States ◽  
Northern Great Plains ◽  
The North ◽  
Induced Currents ◽  
Magnetometer Arrays

Magnetic disturbance fields were recorded during the spring and fall of 1969 with two magnetometer arrays in the Great Plains province of the United States. The purpose of these studies was to map magnetic variation anomalies arising from inhomogeneities of crustal electrical conductivity; we wished to find regions where plane layered models yield apparent resistivity curves that are adequate approximations to curves determined from magnetotelluric measurements. Variation anomalies were found to be related to lateral changes in electrical conductivity of the upper crust, changes associated with sedimentary features. In southeast Oklahoma, induced currents are concentrated in the conductivity sediments of the deep Anadarko basin. These currents give rise to attenuated vertical variation fields to the west and south of the basin and to enhanced vertical fields to the north and northeast. Reversed vertical fields are observed for stations in north central Texas, close to the Ouachita tectonic belt which separates Paleozoic sediments in West Texas from younger sediments in the Gulf Coast plains. This distribution of fields indicates concentration of induced currents in the highly conductive coastal plains sediments. A small variation anomaly is associated with the region of the midcontinent gravity high in the northern Great Plains. The anomaly is probably caused by currents in the sedimentary troughs on the steep flanks of the Precambrian basalts, which give rise to the gravity anomaly.

scholarly journals A comparison of multiscale variations of decade-long cloud fractions from six different platforms over the Southern Great Plains in the United States

2014 ◽  
Vol 119 (6) ◽  
pp. 3438-3459 ◽  
Author(s):  
Wei Wu ◽  
Yangang Liu ◽  
Michael P. Jensen ◽  
Tami Toto ◽  
Michael J. Foster ◽  
...  
Keyword(s):  
United States ◽  
Great Plains ◽  
The United States ◽  
Southern Great Plains

scholarly journals Drought and Pluvial Dipole Events within the Great Plains of the United States

2015 ◽  
Vol 54 (9) ◽  
pp. 1886-1898 ◽  
Author(s):  
Jordan Christian ◽  
Katarina Christian ◽  
Jeffrey B. Basara
Keyword(s):  
United States ◽  
Standard Deviation ◽  
Great Plains ◽  
Spatial Scales ◽  
The United States ◽  
Northern Great Plains ◽  
High Plains ◽  
Southern Great Plains ◽  
One Year ◽  
The U.S

AbstractThe purpose of this study was to quantify dipole events (a drought year followed by a pluvial year) for various spatial scales including the nine Oklahoma climate divisions and the author-defined regions of the U.S. Southern Great Plains (SGP), High Plains (HP), and Northern Great Plains (NGP). Analyses revealed that, on average, over twice as many standard deviation (STDEV) dipoles existed in the latter half of the dataset (1955–2013) relative to the first half (1896–1954), suggesting that dramatic increases in precipitation from one year to the next within the Oklahoma climate divisions are increasing with time. For the larger regions within the Great Plains of the United States, the percent chance of a significant pluvial year following a significant drought year was approximately 25% of the time for the SGP and NGP and approximately 16% of the time for the HP. The STDEV dipole analyses further revealed that the frequency of dipoles was consistent between the first and second half of the dataset for the NGP and HP but was increasing with time in the SGP. The temporal periods of anomalous precipitation during relative pluvial years within the STDEV dipole events were unique for each region whereby October occurred most frequently (70%) within the SGP, September occurred most frequently (60%) within the HP, and May occurred most frequently (62%) within the NGP.

The Temporal Evolution of Convective Indices in Storm-Producing Environments

2008 ◽  
Vol 23 (5) ◽  
pp. 786-794 ◽  
Author(s):  
Timothy J. Wagner ◽  
Wayne F. Feltz ◽  
Steven A. Ackerman
Keyword(s):  
United States ◽  
Temporal Resolution ◽  
Great Plains ◽  
Wind Shear ◽  
Temporal Evolution ◽  
The United States ◽  
Severe Weather ◽  
Wind Profiler ◽  
Southern Great Plains ◽  
Tornadic Storms

Abstract Temporal changes in stability and shear associated with the development of thunderstorms are quantified using the enhanced temporal resolution of combined Atmospheric Emitted Radiance Interferometer (AERI) thermodynamic profile retrievals and National Oceanic and Atmospheric Administration (NOAA) 404-MHz wind profiler observations. From 1999 to 2003, AERI systems were collocated with NOAA wind profilers at five sites in the southern Great Plains of the United States, creating a near-continuous dataset of atmospheric soundings in both the prestorm and poststorm environments with a temporal resolution of up to 10 min between observations. Median values for several standard severe weather indices were calculated for tornadic storms and nontornadic supercells. It was found that instability generally increases throughout the preconvective period, reaching a peak roughly 1 h before a tornado forms or a nontornadic supercell forms large hail. Wind shear for both tornadic and nontornadic storms starts to increase roughly 3 h before storm time. However, indices are highly variable between time and space and may not be representative of the environment at large.

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