scholarly journals Cloud-to-Ground Lightning Flash Density and Thunderstorm Day Distributions over the Contiguous United States Derived from NLDN Measurements: 1993–2018

2019 ◽  
Vol 148 (1) ◽  
pp. 313-332 ◽  
Author(s):  
Thomas L. Koehler
Keyword(s):  
United States ◽  
The United States ◽  
Horizontal Resolution ◽  
Precipitation Anomaly ◽  
Lightning Flash ◽  
Southern Rocky Mountains ◽  
Weather Observations ◽  
Cloud To Ground Lightning ◽  
The Mean ◽  
Southern Florida

Abstract This study employs cloud-to-ground (CG) lightning flash data from the U.S. National Lightning Detection Network (NLDN) to examine temporal and spatial distributions of lightning flash and thunderstorm day (TD) occurrences over the contiguous United States from 1993 to 2018. TD distributions are estimated from NLDN CG flashes using 4 thunder audibility approximations: 5 and 10 nautical mile (n mi; 1 n mi = 1.852 km) audibility ranges, and minima of 1 and 2 flashes within the audibility range. The 26-yr period examined is longer than previous studies using NLDN data, and the TD results can be compared directly to climatologies derived from surface weather observations dating back to the late 1890s. Results based on the abundant NLDN data avoid limitations introduced by the coarse horizontal resolution of surface observations inherent in pre-NLDN TD climatologies. Annual mean flash density and annual and monthly mean TD distributions are derived from almost 568 million NLDN CG flashes. A mean annual maximum of more than 16 flashes km−2 is found near Tampa, Florida. The mean annual TD maximum of 113 days (from at least 2 flashes within 10 n mi) occurs in southern Florida. Regions exceeding 70 TDs are found from eastern Texas eastward into Florida, and over the southern Rocky Mountains. Large positive deviations from the mean number of TDs extend from Texas northwestward into Colorado during 2003–07, followed by large negative deviations over the same region during 2008–12. Both deviation patterns are similar to expected summertime precipitation anomaly patterns over the United States during El Niño and La Niña years, respectively.

scholarly journals Diurnal Variations of NLDN-Reported Cloud-to-Ground Lightning in the United States

2014 ◽  
Vol 142 (3) ◽  
pp. 1037-1052 ◽  
Author(s):  
Ronald L. Holle
Keyword(s):  
United States ◽  
The United States ◽  
Maximum Activity ◽  
Lightning Flash ◽  
Diurnal Changes ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
Local Mean ◽  
Composite Maps ◽  
Mean Time

Abstract National maps of cloud-to-ground lightning flash density (in flashes per square kilometer per year) for one or more years have been produced since the National Lightning Detection Network (NLDN) was first deployed across the contiguous United States in 1989. However, no single publication includes maps of cloud-to-ground flash density across the domain and adjacent areas during the entire diurnal cycle. Cloud-to-ground lightning has strong and variable diurnal changes across the United States that should be taken into account for outdoor lightning-vulnerable activities, particularly those involving human safety. For this study, NLDN cloud-to-ground flash data were compiled in 20 km by 20 km grid squares from 2005 to 2012 for the lower 48 states. A unique feature of this study is that maps were prepared to coincide with local time, not time zones. NLDN flashes were assigned to 2-h time periods in 5° longitude bands. Composite maps of the 2-h periods with the most lightning in each grid square were also prepared. The afternoon from 1200 to 1800 local mean time provides two-thirds of the day’s lightning. However, lightning activity starts before noon over western mountains and onshore along the Atlantic and Gulf of Mexico coasts. These areas are where recurring lightning-vulnerable recreation and workplace activities should expect the threat at these times, rather than view them as an anomaly. An additional result of the study is the midday beginning of lightning over the higher terrain of the western states, then the maximum activity moves steadily eastward. These storms pose a threat to late-afternoon and evening recreation. In some Midwest and plains locations, lightning is most frequent after midnight.

scholarly journals The Daily Cloud-to-Ground Lightning Flash Density in the Contiguous United States and Finland

2011 ◽  
Vol 139 (5) ◽  
pp. 1323-1337 ◽  
Author(s):  
Antti Mäkelä ◽  
Pekka Rossi ◽  
David M. Schultz
Keyword(s):  
United States ◽  
Detection Efficiency ◽  
Quantitative Measure ◽  
The United States ◽  
Lightning Flash ◽  
Upper Midwest ◽  
Lightning Detection ◽  
Operational Forecasting ◽  
Central United States ◽  
Cloud To Ground Lightning

A method is developed to quantify thunderstorm intensity according to cloud-to-ground lightning flashes (hereafter ground flashes) determined by a lightning-location sensor network. The method is based on the ground flash density ND per thunderstorm day (ground flashes per square kilometer per thunderstorm day) calculated on 20 km × 20 km fixed squares. Because the square size roughly corresponds to the area covered by a typical thunderstorm, the flash density for one square defines a unit thunderstorm for the purposes of this study. This method is tested with ground flash data obtained from two nationwide lightning-location systems: the National Lightning Detection Network (NLDN) in the contiguous United States and the portion of the Nordic Lightning Information System (NORDLIS) in Finland. The distribution of daily ground flash density ND is computed for all of Finland and four 800 000 km2 regions in the United States (identified as western, central, eastern, and Florida). Although Finland and all four U.S. regions have median values of ND of 0.01–0.03 flashes per square kilometer per thunderstorm day—indicating that most thunderstorms produce relatively few ground flashes regardless of geographical region—the most intense 1% of the storms (as measured by the 99th percentiles of the ND distributions within each region) show much larger differences among regions. For example, the most intense 1% of the ND distributions is 1.3 flashes per square kilometer per thunderstorm day in the central U.S. region, but only 0.2 flashes per square kilometer per thunderstorm day in Finland. The spatial distribution of the most intense 1% of the ND distributions illustrates that the most intense thunderstorm days occur in the central United States and upper Midwest, which differs from the maxima of the average annual flash density NA and the number of thunderstorm days TD, both of which occur in Florida and along the coast of the Gulf of Mexico. This method for using ND to quantify thunderstorm intensity is applicable to any region as long as the detection efficiency of the lightning-location network is high enough or known. This method can also be employed in operational forecasting to provide a quantitative measure of the lightning intensity of thunderstorms relative to climatology.

scholarly journals Seasonal, Monthly, and Weekly Distributions of NLDN and GLD360 Cloud-to-Ground Lightning

2016 ◽  
Vol 144 (8) ◽  
pp. 2855-2870 ◽  
Author(s):  
Ronald L. Holle ◽  
Kenneth L. Cummins ◽  
William A. Brooks
Keyword(s):  
United States ◽  
New England ◽  
The United States ◽  
Lightning Flash ◽  
Time Space ◽  
Lightning Detection ◽  
Cloud To Ground Lightning ◽  
Annual Total ◽  
The Caribbean ◽  
Using Data

Abstract Annual maps of cloud-to-ground lightning flash density have been produced since the deployment of the National Lightning Detection Network (NLDN). However, a comprehensive national summary of seasonal, monthly, and weekly lightning across the contiguous United States has not been developed. Cloud-to-ground lightning is not uniformly distributed in time, space, or frequency. Knowledge of these variations is useful for understanding meteorological processes responsible for lightning occurrence, planning outdoor events, anticipating impacts of lightning on power reliability, and relating to severe weather. To address this gap in documentation of lightning occurrence, the variability on seasonal, monthly, and weekly scales is first addressed with NLDN flash data from 2005 to 2014 for the 48 states and adjacent regions. Flash density and the percentage of each season’s portion of the annual total are compiled. In spring, thunderstorms occur most often over southeastern states. Lightning spreads north and west until by June, most areas have lightning. New England, the northern Rockies, most of Canada, and the Florida Peninsula have a small percentage of lightning outside of summer. Arizona and portions of adjacent states have the highest incidence in July and August. Flash densities reduce in September in most regions. This seasonal, monthly, and weekly overview complements a recent study of diurnal variations of flashes to document when and where lightning occurs over the United States. NLDN seasonal maps indicate a summer lightning dominance in the northern and western United States that extends into Canada using data compiled from GLD360 network observations. GLD360 also extends NLDN seasonal maps and percentages into Mexico, the Caribbean, and offshore regions.

scholarly journals Longer Residence in the United States is Associated With More Physical Function Limitations in African Immigrant Older Adults

2020 ◽  
pp. 073346482097760
Author(s):  
Manka Nkimbeng ◽  
Yvonne Commodore-Mensah ◽  
Jacqueline L. Angel ◽  
Karen Bandeen-Roche ◽  
Roland J. Thorpe ◽  
...  
Keyword(s):  
United States ◽  
Older Adults ◽  
Confidence Interval ◽  
Physical Function ◽  
Racial Discrimination ◽  
African Immigrants ◽  
The United States ◽  
African Immigrant ◽  
High Discrimination ◽  
The Mean

Acculturation and racial discrimination have been independently associated with physical function limitations in immigrant and United States (U.S.)-born populations. This study examined the relationships among acculturation, racial discrimination, and physical function limitations in N = 165 African immigrant older adults using multiple linear regression. The mean age was 62 years ( SD = 8 years), and 61% were female. Older adults who resided in the United States for 10 years or more had more physical function limitations compared with those who resided here for less than 10 years ( b = −2.62, 95% confidence interval [CI] = [–5.01, –0.23]). Compared to lower discrimination, those with high discrimination had more physical function limitations ( b = −2.51, 95% CI = [–4.91, –0.17]), but this was no longer significant after controlling for length of residence and acculturation strategy. Residing in the United States for more than 10 years is associated with poorer physical function. Longitudinal studies with large, diverse samples of African immigrants are needed to confirm these associations.

scholarly journals A Retrospective Analysis of Softball-Related Head and Facial Injuries Treated in United States Emergency Departments, 2013-2017

2019 ◽  
Vol 7 (2) ◽  
pp. 232596711982566 ◽  
Author(s):  
John S. Strickland ◽  
Marie Crandall ◽  
Grant R. Bevill
Keyword(s):  
United States ◽  
Head Injuries ◽  
The United States ◽  
Weighted Estimate ◽  
Body Parts ◽  
Facial Injuries ◽  
Closed Head Injuries ◽  
Closed Head ◽  
The Mean ◽  
Race Ethnicity

Background: Softball is a popular sport played through both competitive and recreational leagues. While head and facial injuries are a known problem occurring from games, little is known about the frequency or mechanisms by which they occur. Purpose: To analyze head/face injury diagnoses and to identify the mechanisms associated with such injuries. Study Design: Descriptive epidemiological study. Methods: A public database was used to query data related to head/facial injuries sustained in softball. Data including age, sex, race/ethnicity, injury diagnosis, affected body parts, disposition, incident location, and narrative descriptions were collected and analyzed. Results: A total of 3324 head and face injuries were documented in the database over the time span of 2013 to 2017, resulting in a nationwide weighted estimate of 121,802 head/face injuries occurring annually. The mean age of the players was 21.5 ± 14.4 years; 72.1% of injured players were female, while 27.9% were male. The most common injury diagnoses were closed head injuries (22.0%), contusions (18.7%), concussions (17.7%), lacerations (17.1%), and fractures (15.1%). The overwhelming majority of injuries involved being struck by a ball (74.3%), followed by colliding with another player (8.3%), colliding with the ground or a fixed object (5.0%), or being struck by a bat (2.8%). For those injuries caused by a struck-by-ball incident, most occurred from defensive play (83.7% were fielders struck by a hit or thrown ball) as opposed to offensive play (12.3% were players hit by a pitch or runners struck by a ball). Although helmet usage was poorly tracked in the database, female players (1.3%) were significantly more likely to have been wearing a helmet at the time of injury than were male players (0.2%) ( P = .002). Conclusion: The present study demonstrates that a large number of head and face injuries occur annually within the United States as a result of softball play. A variety of injuries were observed, with the majority involving defensive players being struck by the ball, which highlights the need for more focus on player safety by stronger adherence to protective headgear usage and player health monitoring.

scholarly journals The Distribution of Glaciers in the Rocky Mountains of the United States

1977 ◽  
Vol 18 (79) ◽  
pp. 325-328 ◽  
Author(s):  
W. L. Graf
Keyword(s):  
United States ◽  
Rocky Mountains ◽  
The United States ◽  
Aerial Photographs ◽  
Northern Rocky Mountains ◽  
Southern Rocky Mountains

AbstractEvidence from aerial photographs, maps, and field checks indicates that 319 glaciers lie in cirques of the Rocky Mountains, south of the United States-Canadian border. On a subcontinental scale, the distribution of glaciers is highly clustered, with larger and denser clusters located in the northern Rocky Mountains. Lesser concentrations of small glaciers occur in the southern Rocky Mountains. The total area of glaciers in the Rocky Mountains of the U.S.A. is 78.9 km2.

scholarly journals Stewart's Wilt Reactions of an International Collection of Zea mays Germ Plasm Inoculated with Erwinia stewartii

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 901-906 ◽  
Author(s):  
Jerald K. Pataky ◽  
Lindsey J. du Toit ◽  
Noah D. Freeman
Keyword(s):  
United States ◽  
Germ Plasm ◽  
Sweet Corn ◽  
The United States ◽  
River Valley ◽  
Ohio River ◽  
Ohio River Valley ◽  
The World ◽  
The Mean ◽  
Stewart's Wilt

Maize accessions were evaluated in 1997, 1998, and 1999 to identify additional sources of Stewart's wilt resistance and to determine if reactions differed among accessions collected from various regions of the United States and throughout the world. The distributions of Stewart's wilt reactions rated from 1 (no appreciable spread of symptoms) to 9 (dead plants) were relatively similar among groups of accessions from all regions of the world except for those from the Mid-Atlantic/Ohio River Valley region of the United States, the southern United States, and the northeastern United States. The mean and median Stewart's wilt rating for 1,991 accessions evaluated in 1997 was 4. The mean Stewart's wilt rating for 245 accessions collected from the Mid-Atlantic/Ohio River Valley region was 3.1, which was significantly lower than that for accessions from all other regions. The mean rating for accessions from the southern United States was 3.7, which also was lower than mean ratings for accessions from all other regions. Ratings from trials in 1997 and 1998 were highly correlated (r = 0.87) for 292 accessions and 15 sweet corn hybrid checks evaluated in both years. Of 20 accessions rated below 2 in 1997 and 1998, seven were from Virginia, seven were from the Ohio River Valley or central Corn Belt of the United States, four were from the northern or western Corn Belt of the United States, and two were from Spain. Ratings for these accessions ranged from 1.7 to 3.1 in 1999. Ratings ranged from 2.6 to 3.7 for F1 hybrids of these accessions crossed with one of two susceptible sweet corn inbreds, CrseW30 or Crse16, which were rated 5.7 and 5.4, respectively. Based on the reactions of this collection of germ plasm, it appears that high levels of Stewart's wilt resistance are prevalent only among accessions collected from areas where the disease has been endemic for several years, whereas moderate levels of resistance can be found in accessions collected from nearly everywhere in the world.

scholarly journals A 5-yr 40-km-Resolution Global Climatology of Superrefraction for Ground-Based Weather Radars

2009 ◽  
Vol 48 (1) ◽  
pp. 89-110 ◽  
Author(s):  
Philippe Lopez
Keyword(s):  
United States ◽  
Electromagnetic Waves ◽  
Vertical Gradient ◽  
Radar Data ◽  
The United States ◽  
Horizontal Resolution ◽  
Trade Wind ◽  
Late Afternoon ◽  
The Balkans ◽  
Radar Images

Abstract The propagation of electromagnetic waves emitted from ground-based meteorological radars is determined by the stratification of the atmosphere. In extreme superrefractive situations characterized by strong temperature inversions or strong vertical gradients of moisture, the radar beam can be deflected toward the ground (ducting or trapping). This phenomenon often results in spurious returned echoes and misinterpretation of radar images such as erroneous precipitation detection. In this work, a 5-yr global climatology of the frequency of superrefractive and ducting conditions and of trapping-layer base height has been produced using refractivity computations from ECMWF temperature, moisture, and pressure analyses at a 40-km horizontal resolution. The aim of this climatology is to better document how frequent such events are, which is a prerequisite for fully benefiting from radar data information for the multiple purposes of model validation, precipitation analysis, and data assimilation. First, the main climatological features are summarized for the whole globe: high- and midlatitude oceans seldom experience superrefraction or ducting whereas tropical oceans are strongly affected, especially in regions where the trade wind inversion is intense and lying near the surface. Over land, seasonal averages of superrefraction (ducting) frequencies reach 80% (40%) over tropical moist areas year-round but remain below 40% (15%) in most other regions. A particular focus is then laid on Europe and the United States, where extensive precipitation radar networks already exist. Seasonal statistics exhibit a pronounced diurnal cycle of ducting occurrences, with averaged frequencies peaking at 60% in summer late afternoon over the eastern half of the United States, the Balkans, and the Po Valley but no ducts by midday. Similarly high ducting frequencies are found over the southwestern coast of the United States at night. A potentially strong reduction of ducting occurrences with increased radar height (especially in midlatitude summer late afternoon) is evidenced by initiating refractivity vertical gradient computations from either the lowest or the second lowest model level. However, installing radar on tall towers also brings other problems, such as a possible amplification of sidelobe clutter echoes.

MMPI-2 Scores of Puerto Rican, Mexican, and U.S. Latino College Students: A Research Note

2000 ◽  
Vol 87 (1) ◽  
pp. 266-268 ◽  
Author(s):  
Jose J. Cabiya ◽  
Denise A. Chavira ◽  
Francisco C. Gomez ◽  
Emilia Lucio ◽  
Jeanett Castellanos ◽  
...  
Keyword(s):  
United States ◽  
College Students ◽  
Puerto Rico ◽  
Standard Deviation ◽  
Puerto Rican ◽  
The United States ◽  
Clinical Scale ◽  
The Mean ◽  
The One ◽  
Scale Data

In this brief report, we present MMPI-2 basic validity and clinical scale data of Latino-descent persons from Puerto Rico ( n = 290), Mexico ( n = 1,920), and the United States ( n = 28). All were administered one of three Spanish translations of the MMPI-2. A review of the mean scores of these respective groups indicates similarities across all scales. Differences among these three groups, with the exception of the Mf scale (which is keyed to sex), were well within the one standard deviation band. More importantly, these findings are promising given the fact that three different translations of the MMPI-2 were applied.

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