scholarly journals Prolonged Dry Episodes over the Conterminous United States: New Tendencies Emerging during the Last 40 Years

2008 ◽  
Vol 21 (9) ◽  
pp. 1850-1862 ◽  
Author(s):  
Pavel Ya Groisman ◽  
Richard W. Knight
Keyword(s):  
United States ◽  
Average Duration ◽  
Warm Season ◽  
Vegetation Period ◽  
Total Precipitation ◽  
Eastern United States ◽  
The Past ◽  
The Mean ◽  
Rain Events ◽  
Precipitation Events

Abstract A disproportionate increase in precipitation coming from intense rain events, in the situation of general warming (thus, an extension of the vegetation period with intensive transpiration), and an insignificant change in total precipitation could lead to an increase in the frequency of a potentially serious type of extreme events: prolonged periods without precipitation (even when the mean seasonal rainfall totals increase). This paper investigates whether this development is already occurring during the past several decades over the conterminous United States, for the same period when changes in frequency of intense precipitation events are being observed. Lengthy strings of “dry” days without sizeable (>1.0 mm) precipitation were assessed only during the warm season (defined as a period when mean daily temperature is above the 5°C threshold) when water is intensively used for transpiration and prolonged periods without sizable rainfall represent a hazard for terrestrial ecosystem’s health and agriculture. During the past four decades, the mean duration of prolonged dry episodes (1 month or longer in the eastern United States and 2 months or longer in the southwestern United States) has significantly increased. As a consequence the return period of 1-month-long dry episodes over the eastern United States has reduced more than twofold from 15 to 6–7 yr. The longer average duration of dry episodes has occurred during a relatively wet period across the country but is not observed over the northwestern United States.

scholarly journals Changes in Intense Precipitation over the Central United States

2012 ◽  
Vol 13 (1) ◽  
pp. 47-66 ◽  
Author(s):  
Pavel Ya. Groisman ◽  
Richard W. Knight ◽  
Thomas R. Karl
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Heavy Precipitation ◽  
The Past ◽  
Extreme Precipitation Events ◽  
Intense Precipitation ◽  
Central United States ◽  
Extreme Rain ◽  
Rain Events ◽  
Precipitation Events

Abstract In examining intense precipitation over the central United States, the authors consider only days with precipitation when the daily total is above 12.7 mm and focus only on these days and multiday events constructed from such consecutive precipitation days. Analyses show that over the central United States, a statistically significant redistribution in the spectra of intense precipitation days/events during the past decades has occurred. Moderately heavy precipitation events (within a 12.7–25.4 mm day−1 range) became less frequent compared to days and events with precipitation totals above 25.4 mm. During the past 31 yr (compared to the 1948–78 period), significant increases occurred in the frequency of “very heavy” (the daily rain events above 76.2 mm) and extreme precipitation events (defined as daily and multiday rain events with totals above 154.9 mm or 6 in.), with up to 40% increases in the frequency of days and multiday extreme rain events. Tropical cyclones associated with extreme precipitation do not significantly contribute to the changes reported in this study. With time, the internal precipitation structure (e.g., mean and maximum hourly precipitation rates within each preselected range of daily or multiday event totals) did not noticeably change. Several possible causes of observed changes in intense precipitation over the central United States are discussed and/or tested.

scholarly journals Recent Changes in United States Extreme 3-Day Precipitation Using the R-CAT Scale

2020 ◽  
Vol 21 (6) ◽  
pp. 1207-1221 ◽  
Author(s):  
Maryam A. Lamjiri ◽  
F. Martin Ralph ◽  
Michael D. Dettinger
Keyword(s):  
United States ◽  
East Coast ◽  
The United States ◽  
Western United States ◽  
Eastern United States ◽  
Atmospheric Rivers ◽  
The Past ◽  
Extreme Precipitation Events ◽  
Precipitation Total ◽  
Precipitation Events

AbstractExtraordinary precipitation events have impacted the United States recently, including Hurricanes Harvey (2017) and Florence (2018), with 3-day precipitation totals larger than any others reported in the United States during the past 70 years. The rainfall category (R-CAT) scaling method is used here to document extreme precipitation events and test for trends nationally. The R-CAT scale uses thresholds of 3-day precipitation total in 100-mm increments (starting with 200 mm) that do not vary temporally or geographically, allowing for simple, intuitive comparisons of extremes over space and time. The paper that introduced the scale only required levels 1–4 to represent historical extremes, finding that R-CATs 3–4 strike the conterminous United States about as frequently as EF 4–5 tornadoes or category 3–5 hurricanes. Remarkably, Florence and Harvey require extending the scale to R-CAT 7 and 9, respectively. Trend analyses of annual maximum 3-day totals (1950–2019) here identify significant increases in the eastern United States, along with declines in Northern California and Oregon. Consistent with these results, R-CAT storms have been more frequent in the eastern, and less frequent in western, United States during the past decade compared to 1950–2008. Tropical storms dominate R-CAT events along the southeastern coast and East Coast with surprising contributions from atmospheric rivers, while atmospheric rivers completely dominate along the West Coast.

Current Status and Future of Regional Seismic Network Monitoring in the Central and Eastern United States

2019 ◽  
Vol 91 (2A) ◽  
pp. 660-676 ◽  
Author(s):  
John E. Ebel ◽  
Martin C. Chapman ◽  
Won-Young Kim ◽  
Mitchell Withers
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Source Parameters ◽  
Seismic Wave Propagation ◽  
Seismic Network ◽  
Current Status ◽  
Future Research ◽  
Eastern United States ◽  
The Past ◽  
Earthquake Source Parameters

Abstract The central and eastern United States (CEUS) is an area of generally low-to-moderate seismic hazard with a number of large cities with high seismic risk, a history of occasional damaging earthquakes, and seismic activity induced by wastewater disposal. Seismic monitoring in the CEUS, which began at the beginning 1900s, has undergone many changes through time. Over the past two decades, broadband digital seismic stations connected by internet communications have become widespread. Modern data processing systems to automatically locate earthquakes and assign event magnitudes in near-real time have become the norm, and, since the inception of the Advanced National Seismic System in 2000, more than 10,000 earthquakes have been located and cataloged. Continuously recorded digital seismic data at 100 samples per second are allowing new avenues of research into earthquake source parameters, ground-motion excitation, and seismic wave propagation. Unfortunately, over the past two decades the number of regional seismic network (RSN) centers has diminished due to consolidations and terminations, as funding has tightened. Nevertheless, the public in different parts of the CEUS still looks to local experts for information when earthquakes take place or when they have questions about earthquakes and seismic hazard. The current RSNs must evolve to encompass the need for local seismic information centers and to serve the needs of present and future research into the causes and effects of CEUS earthquakes.

scholarly journals Evaluation of the U.S. Mothbean Collection for Seed Yield Potential in Virginia and Nutritional Composition of Freshly Harvested Seed

2016 ◽  
Vol 26 (6) ◽  
pp. 820-824
Author(s):  
Harbans L. Bhardwaj ◽  
Anwar A. Hamama
Keyword(s):  
United States ◽  
Nutritional Composition ◽  
Yield Potential ◽  
Eastern United States ◽  
Tepary Bean ◽  
Legume Crop ◽  
Iron And Zinc ◽  
The Mean ◽  
Calcium Iron ◽  
Seed Yields

Even though mothbean (Vigna aconitifolia), a drought- and heat-tolerant crop, may have potential in the eastern United States, information about its production in this region is not available. To characterize potential seed yields and preliminary nutritional quality, 54 accessions were grown near Petersburg, VA, during 2011, 2012, and 2013. The seed yields varied from 48 to 413 lb/acre. The mean concentrations of protein, calcium, iron, and zinc in mature mothbean seed were 21.9%, 0.17%, 64.8 ppm, and 37.5 ppm, respectively. These values compared well with those in mungbean (Vigna radiata) and tepary bean (Phaseolus acutifolius). The results demonstrated that mothbean has considerable potential as an alternative, new food legume crop in Virginia and eastern United States.

scholarly journals A Dynamical and Statistical Characterization of U.S. Extreme Precipitation Events and Their Associated Large-Scale Meteorological Patterns

2017 ◽  
Vol 30 (4) ◽  
pp. 1307-1326 ◽  
Author(s):  
Siyu Zhao ◽  
Yi Deng ◽  
Robert X. Black
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Warm Season ◽  
Base Function ◽  
Regional Patterns ◽  
Statistical Characterization ◽  
Climate System Model ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract Regional patterns of extreme precipitation events occurring over the continental United States are identified via hierarchical cluster analysis of observed daily precipitation for the period 1950–2005. Six canonical extreme precipitation patterns (EPPs) are isolated for the boreal warm season and five for the cool season. The large-scale meteorological pattern (LMP) inducing each EPP is identified and used to create a “base function” for evaluating a climate model’s potential for accurately representing the different patterns of precipitation extremes. A parallel analysis of the Community Climate System Model, version 4 (CCSM4), reveals that the CCSM4 successfully captures the main U.S. EPPs for both the warm and cool seasons, albeit with varying degrees of accuracy. The model’s skill in simulating each EPP tends to be positively correlated with its capability in representing the associated LMP. Model bias in the occurrence frequency of a governing LMP is directly related to the frequency bias in the corresponding EPP. In addition, however, discrepancies are found between the CCSM4’s representation of LMPs and EPPs over regions such as the western United States and Midwest, where topographic precipitation influences and organized convection are prominent, respectively. In these cases, the model representation of finer-scale physical processes appears to be at least equally important compared to the LMPs in driving the occurrence of extreme precipitation.

scholarly journals Multiple Treatment Meta-Analysis of Products Evaluated for Control of Fire Blight in the Eastern United States

2011 ◽  
Vol 101 (5) ◽  
pp. 512-522 ◽  
Author(s):  
H. K. Ngugi ◽  
B. L. Lehman ◽  
L. V. Madden
Keyword(s):  
United States ◽  
Biological Control ◽  
Disease Control ◽  
Plant Defense ◽  
Fire Blight ◽  
Pantoea Agglomerans ◽  
Effect Sizes ◽  
Eastern United States ◽  
The Mean ◽  
Prohexadione Calcium

The aim of this analysis was to estimate the effect sizes and consistency of products evaluated for fire blight control in the eastern United States over the last decade. Because only 3% of the 69 studies published from 2000 to 2008 explicitly presented a measure of within-study variability, a method for estimating the least significant difference (LSD) and, hence the sampling variance, for studies with at least two significant mean separations in the presented mean multiple comparisons was developed. Lin's concordance analysis indicated that the estimated LSD was an accurate predictor of the actual LSD based on 35 studies in a calibration evaluation (ρc = 0.997). Separate multi-treatment random-effects meta-analyses were performed for three control categories: antibiotics, biological control, and plant defense-activating products and mean log response ratios relative to the nontreated controls ([Formula: see text]) were computed for each treatment and then back-transformed to obtain the mean percent disease control. None of the products evaluated performed as well as streptomycin, the standard product for fire blight control, for which the mean disease control was 68.6%. As a group, experimental antibiotics provided the best fire blight control with mean effect sizes ranging from 59.7 to 61.7%. Among the biological controls, the best control was noted for treatments combining the antibiotic streptomycin with a product based on Pantoea agglomerans (55.0% mean disease reduction) or Bacillus subtilis (53.9%). Mean disease control was 31.9, 25.7, and 22.6%, respectively, for products based on B. subtilis, Pantoea agglomerans, and Pseudomonas fluorescens without an antibiotic, suggesting that the higher efficacy of the combination treatments was due to the antibiotic. Among the plant defense-activating products, prohexadione calcium had the highest and most consistent effect size (50.7% control), while other products provided modest mean disease control of between 6.1 and 25.8%. Percent control values were significantly moderated by study location and cultivar used in the study, and were smaller, but more variable, when products were tested under high disease intensity compared with low disease intensity. Results indicate that wide-scale use of biological control and plant defense-activating products in the eastern United States is likely to remain low.

Introduction and recent range expansion in the moss Ptychomitrium serratum (Ptychomitriaceae) in the Southern and Eastern United StatesThis paper is one of a selection of papers published as part of the special Schofield Gedenkschrift.

Botany ◽  
2010 ◽  
Vol 88 (4) ◽  
pp. 336-344 ◽  
Author(s):  
Norton G. Miller ◽  
Sean C. Robinson
Keyword(s):  
United States ◽  
New York ◽  
South Carolina ◽  
New Mexico ◽  
New York State ◽  
Eastern United States ◽  
East Texas ◽  
The Past ◽  
Primary Means ◽  
Selection Of

The moss Ptychomitrium serratum (C. Müll. Hal. ex Schimp.) Besch., is native to Mexico and parts of western Texas and southern New Mexico, and it is a rare adventive in the area from East Texas and Louisiana to Missouri, Tennessee, South Carolina, and northward to locations near the coast in New York State and Massachusetts. In the adventive part of this calcicole’s range, all collections are from the past 50 years. Concrete, mortar, and rarely asphalt shingle are its only known substrata in this region, which contrasts sharply with its common occurrence on limestone in the native portion of its range. These observations indicate recent, perhaps on-going, immigration into the eastern United States and dispersal from established populations in this region. This monoicous moss commonly produces spores, which are its primary means of spread. Given the low density occurrences in the adventive portion of the range of P. serratum, dispersal may be generally northeastward from Mexico – Texas – New Mexico, following northeastward storm tracks in the southern and eastern United States. The apparently recent spread of this moss does not show obvious reliance on any direct human activity.

Evaluation of Historical and Future Cool Season Precipitation over the Eastern United States and Western Atlantic Storm Track Using CMIP5 Models

2015 ◽  
Vol 28 (2) ◽  
pp. 451-467 ◽  
Author(s):  
Kelly Lombardo ◽  
Brian A. Colle ◽  
Zhenhai Zhang
Keyword(s):  
United States ◽  
Global Climate Model ◽  
Storm Track ◽  
Cmip5 Models ◽  
Eastern United States ◽  
Cool Season ◽  
Western Atlantic ◽  
Extreme Precipitation Events ◽  
Projected Changes ◽  
Precipitation Events

Abstract This study analyzed the contribution of cyclones to projected changes in cool season (1 November–31 March) precipitation over the eastern United States and western North Atlantic Ocean. First, global climate model simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5) were compared to Global Precipitation Climatology Project (GPCP) and Climate Prediction Center (CPC) precipitation analyses for the period 1979–2004. The CMIP5 ensemble mean realistically reproduced the historical distribution of regional precipitation with no discernable effect because of model spatial resolution. Subsequently, the projected changes in precipitation on cyclone and noncyclone days under the representative concentration pathway 8.5 (RCP8.5) scenario were quantified. While precipitation on both types of days was projected to increase, the increase on noncyclone days (23%) was greater than the increase on cyclone days (12%). The increase in precipitation on cyclone days occurred despite a decrease in the number of cyclone days. This increase can be attributed primarily to a shift toward more frequent extreme precipitation events coupled with a decline in light precipitation events.

scholarly journals Climatology and Environmental Characteristics of Extreme Precipitation Events in the Southeastern United States

2015 ◽  
Vol 143 (3) ◽  
pp. 718-741 ◽  
Author(s):  
Benjamin J. Moore ◽  
Kelly M. Mahoney ◽  
Ellen M. Sukovich ◽  
Robert Cifelli ◽  
Thomas M. Hamill
Keyword(s):  
United States ◽  
Extreme Precipitation ◽  
Southeastern United States ◽  
Warm Season ◽  
Stage Iv ◽  
Flow Patterns ◽  
Water Vapor Transport ◽  
Cool Season ◽  
Extreme Precipitation Events ◽  
Precipitation Events

Abstract This paper documents the characteristics of extreme precipitation events (EPEs) in the southeastern United States (SEUS) during 2002–11. The EPEs are identified by applying an object-based method to 24-h precipitation analyses from the NCEP stage-IV dataset. It is found that EPEs affected the SEUS in all months and occurred most frequently in the western portion of the SEUS during the cool season and in the eastern portion during the warm season. The EPEs associated with tropical cyclones, although less common, tended to be larger in size, more intense, and longer lived than “nontropical” EPEs. Nontropical EPEs in the warm season, relative to those in the cool season, tended to be smaller in size and typically involved more moist, conditionally unstable conditions but weaker dynamical influences. Synoptic-scale composites are constructed for nontropical EPEs stratified by the magnitude of vertically integrated water vapor transport (IVT) to examine distinct scenarios for the occurrence of EPEs. The composite results indicate that “strong IVT” EPEs occur within high-amplitude flow patterns involving strong transport of moist, conditionally unstable air within the warm sector of a cyclone, whereas “weak IVT” EPEs occur within low-amplitude flow patterns featuring weak transport but very moist and conditionally unstable conditions. Finally, verification of deterministic precipitation forecasts from a reforecast dataset based on the NCEP Global Ensemble Forecast System reveals that weak-IVT EPEs were characteristically associated with lower forecast skill than strong-IVT EPEs. Based on these results, it is suggested that further research should be conducted to investigate the forecast challenges associated with EPEs in the SEUS.

Climatic variability in the eastern United States over the past millennium from Chesapeake Bay sediments

Geology ◽  
2000 ◽  
Vol 28 (1) ◽  
pp. 3-6 ◽  
Author(s):  
T. Cronin ◽  
D. Willard ◽  
A. Karlsen ◽  
S. Ishman ◽  
S. Verardo ◽  
...  
Keyword(s):  
United States ◽  
Chesapeake Bay ◽  
Climatic Variability ◽  
Eastern United States ◽  
The Past ◽  
Past Millennium
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