INVESTIGATION OF THE DRIFTS OF THE EFFECTIVE POINT OF RADIO REFLECTION ALONG A METEOR TRAIN

1958 ◽  
Vol 36 (12) ◽  
pp. 1601-1623 ◽  
Author(s):  
M. Srirama Rao ◽  
R. L. Armstrong
Keyword(s):  
Atmospheric Turbulence ◽  
Doppler Radar ◽  
Theoretical Interpretation ◽  
Field Station ◽  
Radio Reflection ◽  
Vertical Scale ◽  
Meteoric Body ◽  
Diffusion Rates ◽  
Different Levels ◽  
Meteor Train

The concept of the effective point of radio reflection from a meteor train has been given on the basis of atmospheric turbulence, on a vertical scale of the order of 100 m to 6 km, in the M region. Some experimental evidence has been provided to support the postulate of its drifting along the train, using meteoric body doppler radar records, taken on 30.02 Mc/s at South Gloucester, during the Geminid shower periods of 1948–50. The velocities (Vs) of the above drifts in the case of 90 observations have been calculated, using the ranges of the observed meteors as obtained from the range–time records taken simultaneously on pulsed radar on 32.7 Mc/s at the Metcalfe Road field station (7.5 km distant). It is found that these velocities tend to have higher values in the case of shorter echo durations and vice versa. Theoretical interpretation of the observed results has been attempted. Reasonable assumptions of the ionization distribution along a meteor train and of diffusion rates at different levels in the M region have been made to derive the echo durations from different portions of a meteor train. Variation of these echo durations with position on the train has been taken into account to calculate the theoretical curves of vertical components of Vs vs. total echo durations, in the case of a Geminid shower. The effect of turbulence on echo durations has been taken into account to explain the observed results successfully.

ANALYSIS OF METEORIC BODY DOPPLER RADAR RECORDS TAKEN DURING A GEMINID SHOWER PERIOD

1958 ◽  
Vol 36 (7) ◽  
pp. 840-854 ◽  
Author(s):  
M. Srirama Rao
Keyword(s):  
Doppler Radar ◽  
The Body ◽  
Upper Atmosphere ◽  
Prevailing Wind ◽  
Linear Variation ◽  
Minute Period ◽  
Meteoric Body ◽  
Periodic Fluctuations ◽  
Meteor Train

The determination of the prevailing wind in the 80–100 km region of the upper atmosphere by a new method, involving the simultaneous use of a CW doppler radar at 30.02 Mc/sec and three-station pulsed radars at about the same frequencies, is presented in this paper. This method involves the determination of the exact location of each observed meteor train and the component of the velocity of its horizontal drift in the direction of the azimuth from Ottawa. A 40-minute period during the Geminid shower on the night of Dec. 10/11, 1948, has been selected for this investigation. Theory for the analysis of the body doppler records is briefly outlined. The prevailing wind speed obtained from the body doppler frequencies (fd) is 54 m/sec. The observed linear variation in the average fd with time, in the case of each meteor, has been explained as caused by the effective point of reflection drifting along its train towards the maximum echo duration level. Periodic fluctuations of fd of the order of 1–3 c.p.s., on the average, have also been observed. The above two phenomena can be explained from a postulate of atmospheric turbulence on a scale of about 1 km or above.

scholarly journals Angiosperms, Los Tuxtlas Biosphere Reserve, Veracruz, Mexico

Check List ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 787 ◽  
Author(s):  
Víctor Arroyo-Rodríguez ◽  
Jacob C. Dunn ◽  
Julieta Benítez-Malvido ◽  
Salvador Mandujano
Keyword(s):  
Introduced Species ◽  
Plant Diversity ◽  
Biosphere Reserve ◽  
Los Tuxtlas ◽  
Check List ◽  
Forest Reserve ◽  
Field Station ◽  
Breast Height ◽  
Mexican Government ◽  
Different Levels

The Los Tuxtlas Reserve has been heavily deforested and fragmented since the 1970’s. Although the flora of Los Tuxtlas has been described previously, most floristic lists come from the large forest reserve of the Los Tuxtlas field station. Here we present a check list of Angiosperms recorded in 45 rainforest fragments (< 1 to 266 ha) located in three landscapes with different levels of deforestation. We sampled all trees, shrubs, lianas, palms and herbs with diameter at breast height (dbh) Ā 2.5 cm within ten 50 m x 2 m plots per fragment. We recorded 9,435 plants belonging to 73 families and 372 species. Fabaceae, Rubiaceae, and Moraceae were best represented. Eight species are classified as Endangered by the Mexican government, and five are human-introduced species. We conclude that the conservation and restoration of all the remaining rainforest fragments are necessary to effectively preserve the plant diversity of this region.

scholarly journals A spectral model for turbulence and microphysics dynamics in an ice cloud

1996 ◽  
Vol 3 (1) ◽  
pp. 23-28 ◽  
Author(s):  
A. J. Palmer
Keyword(s):  
Doppler Radar ◽  
Spectral Model ◽  
Velocity Measurements ◽  
Ice Clouds ◽  
One Dimensional ◽  
Mixing Ratios ◽  
Ice Cloud ◽  
Microphysical Properties ◽  
Vertical Scale ◽  
Direct Measurements

Abstract. A one-dimensional, nine-mode spectral model for temperature, velocity, and the mixing ratios of suspended and precipitating ice-particle components is shown to be consistent with ice-cloud observations. The observations include Doppler radar time-series measurements of a single winter ice cloud and direct measurements of mean particle size vs. icewater content for a set of ice clouds. Fitting of the model to the Doppler vertical-velocity measurements allows a prediction to be made of the vertical scale and turbulent Prandtl number active in the ice-cloud vertical motions. The model is then used to explore the question of how turbulence and gravity-wave motions affect the microphysical properties of an ice cloud. The model predicts interesting dynamical effects on the mixing ratios due to these motions, but no significant effects on the time-averaged microphysical quantities.

Doppler Radar Measurements of Spatial Turbulence Intensity in the Atmospheric Boundary Layer

2019 ◽  
Vol 58 (7) ◽  
pp. 1535-1555 ◽  
Author(s):  
James B. Duncan ◽  
Brian D. Hirth ◽  
John L. Schroeder
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Atmospheric Turbulence ◽  
Turbulence Intensity ◽  
Large Scale ◽  
Doppler Radar ◽  
Atmospheric Stability ◽  
Temporal Analysis ◽  
Spatiotemporal Variability ◽  
Complex Flow

AbstractRemote sensing instruments that scan have the ability to provide high-resolution spatial measurements of atmospheric boundary layer winds across a region. However, the time required to collect the volume of measurements used to produce this spatial representation of atmospheric winds typically limits the extraction of atmospheric turbulence information using traditional temporal analysis techniques. To overcome this constraint, a spatial turbulence intensity (STI) metric was developed to quantify atmospheric turbulence intensity (TI) through analysis of spatial wind field variability. The methods used to determine STI can be applied throughout the measurement domain to transform the spatially distributed velocity fields to analogous measurement maps of STI. This method enables a comprehensive spatial characterization of atmospheric TI. STI efficacy was examined across a range of wind speeds and atmospheric stability regimes using both single- and dual-Doppler measurements. STI demonstrated the ability to capture rapid fluctuations in TI and was able to discern large-scale TI trends consistent with the early evening transition. The ability to spatially depict atmospheric TI could benefit a variety of research disciplines such as the wind energy industry, where an understanding of wind plant complex flow spatiotemporal variability is limited.

The influence of sea breeze on mold spore dispersion

2021 ◽  
Vol 42 (3) ◽  
pp. 222-227
Author(s):  
Leonard Bielory ◽  
Louis Bowers ◽  
Rivka Marcus ◽  
Rich Dunk
Keyword(s):  
New Jersey ◽  
Doppler Radar ◽  
Meteorological Data ◽  
Sea Breeze ◽  
Airway Disease ◽  
Allergic Airway Disease ◽  
Field Station ◽  
Rutgers University ◽  
Significant Difference ◽  
Mold Spore

Background: Many allergists consider the ocean breeze to be free of allergens and recommend visits to the coast for relief; however, the coast may perpetuate an allergenic environment. Objective: This study investigated the sea breeze's impact on spore dispersion between coastal and inland sites, and the potential implications of sea breeze on human health and coastal resources. Methods: Spore sampling occurred during 2006 by using pollen samplers. Samplers were located at the Rutgers University Institute of Marine and Coastal Sciences Marine Field Station and the Rutgers University Pinelands Field Station. Statistical analysis was performed on the spore data to compare concentrations from the various locations. The effect of sea breeze circulation on particulate matter was analyzed from meteorological data collected in 2006. Sea breeze data were collected from simulations, Doppler radar, and meteorological towers at varying heights. Results: There was no significant difference between the total spore concentration at the New Jersey coast and the New Jersey Pinelands canopy. Conclusion: Sea breeze has been shown to favor aerobiologic transfers from coastal seawater to land, but the immediate environment (floor) still remains a primary determinant of affecting an individual's allergic airway disease. Results of some studies have shown that coastal environments may favor the onset allergic airway, but in our study this seemed to be equivalent to the floor (or immediate locale) of an individual affected with allergy. However, the sea breeze effect seemed to have the ability to impact allergic airway disease (AAD) populations not only living along the coasts but of those living up to 130 km inland and potentially those living in the Philadelphia metropolitan area.

Dependence of Intergranular Fracture on Boundary Topography and Cohesion

1973 ◽  
Vol 31 ◽  
pp. 150-151
Author(s):  
J. E. Doherty ◽  
A. F. Giamei ◽  
B. H. Kear ◽  
C. W. Steinke
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Nickel Base Superalloy ◽  
Boundary Shear ◽  
Room Temperature Ductility ◽  
Solid Solution Matrix ◽  
Nickel Base ◽  
Solution Matrix ◽  
Different Levels ◽  
Base Superalloy

Recently we have been investigating a class of nickel-base superalloys which possess substantial room temperature ductility. This improvement in ductility is directly related to improvements in grain boundary strength due to increased boundary cohesion through control of detrimental impurities and improved boundary shear strength by controlled grain boundary micros true tures.For these investigations an experimental nickel-base superalloy was doped with different levels of sulphur impurity. The micros tructure after a heat treatment of 1360°C for 2 hr, 1200°C for 16 hr consists of coherent precipitates of γ’ Ni3(Al,X) in a nickel solid solution matrix.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Sign in / Sign up

Export Citation Format

Share Document