Collision frequency of electrons in the F region

1970 ◽  
Vol 48 (6) ◽  
pp. 653-658 ◽  
Author(s):  
C. S. G. K. Setty ◽  
A. R. Jain ◽  
M. K. Vyawahare
Keyword(s):  
Collision Frequency ◽  
Extraordinary Wave ◽  
Early Morning ◽  
Radio Waves ◽  
Height Range ◽  
F Region ◽  
Geographical Latitude ◽  
Late Evening ◽  
Wave Modes

The collision frequency of electrons in the F region of the ionosphere has been measured at Delhi (geographical latitude 28°38′ N, geographical longitude 77°13′ E) using a method similar to that suggested by Appleton. The amplitude and group path of short radio waves vertically incident on the F region of the ionosphere have been measured simultaneously at a suitable frequency (for both the ordinary and extraordinary wave modes) in early morning and late evening hours, corresponding to times of appearance and disappearance of the echo, respectively. Simultaneous changes in amplitude and group path are related to deduce the collision frequency. Some selected records taken near the time of sunrise have been analyzed and the values of collision frequency are found to be (4.2 ± 0.5) × 103 and (3.5 ± 0.5) × 103 s−1 for the ordinary and extraordinary waves, respectively, in the true-height range of 270–310 km.

D -region electron distributions in middle latitudes deduced from the reflexion of long radio waves

1966 ◽  
Vol 291 (1426) ◽  
pp. 413-437 ◽  
Keyword(s):  
Electron Concentration ◽  
Electron Distribution ◽  
Collision Frequency ◽  
Structural Features ◽  
Height Distribution ◽  
Radio Waves ◽  
Height Range ◽  
Small Peak ◽  
Wide Range ◽  
Full Wave Analysis

A method of full-wave analysis is used to compute the theoretical values of reflexion and conversion coefficients of long and very long radio waves incident on a horizontally stratified ionosphere having a postulated height distribution of electron concentration and collision frequency. With reasonable values of collision frequency (§4 and figure 1), the electron distribution is then progressively changed until the computed values of the reflexion parameters agree with experimental measurements over a range of frequencies from 16 to 100 kc/s at both steep and oblique incidence. Height distributions of electrons which would explain the results of experiments made at different times of the day, the year, the solar cycle, and during an eclipse, are presented in figures 2 to 7. It is shown that these distributions are consistent with a wide range of experimental results on other frequencies. Important structural features in the electron distribution are noticed: by day (figure 2) there is a small peak of electron concentration near 64 km, a sharp gradient near 74 km, and a shallow gradient in the height range 75 to 88 km which joins the bottomside of the E -layer; at night (figure 7) electron concentrations below 80 km are very small, and there is a sharp gradient near 90 km. The electron concentrations above and below 70 km depend in different ways on the intensity of solar radiation.

scholarly journals Usage of regularization techniques for effective electron collision frequency determination from oblique ionospheric sounding

1996 ◽  
Vol 14 (8) ◽  
pp. 811-815 ◽  
Author(s):  
P. F. Denisenko ◽  
N. V. Nastasyina ◽  
V. I. Vodolazkin
Keyword(s):  
Measurement Errors ◽  
Computer Modelling ◽  
Collision Frequency ◽  
Electron Collision ◽  
Radio Waves ◽  
Absorption Data ◽  
Effective Electron ◽  
F Region ◽  
Electron Collision Frequency ◽  
Regularization Techniques

Abstract. Computer modelling is used to investigate the possibility of determining ionospheric parameters from slightly oblique ionospheric soundings, using absorption data for decametric radio waves of different polarization. It is shown that with mean square measurement errors of 0.5 dB, and using regularization algorithms to solve the inverse problems, electron collision frequency profiles can be obtained for the night F-region with errors of less than 30%. Both temperatures of electrons and neutrals are also determined to within 10%.

Studies on the ionization produced by metallic salts in flames I. The determination of the collision frequency of electrons in coal-gas/air flames

1950 ◽  
Vol 201 (1067) ◽  
pp. 480-488 ◽  
Keyword(s):  
Conversion Factor ◽  
Collision Frequency ◽  
Metal Salt ◽  
Alkali Metal Salt ◽  
Electron Content ◽  
Radio Waves ◽  
Coal Gas ◽  
Flame Ionization ◽  
Metallic Salts

As an introduction to the study of reactions contingent on ionization in flames, an experimental measurement has been made of the collision frequency of electrons with molecules in coal-gas/air flames, containing added alkali metal salt. This quantity is an important parameter in the expression relating the electron content of a flame with the attenuation of centimetric radio waves by it. This attenuation has been chosen as a convenient method of investigating flame ionization. The form of the results obtained agree well with the predictions of theory, a uniform difference of about 20 % between measured collision frequency and that calculated on a very simple gas kinetic hypothesis being obtained. A suitable conversion factor has been evolved for proceeding from attenuation of 3 cm. waves to electron concentration/cm. 3 .

scholarly journals Protein Supplementation and Grazing Behavior for Cows on Differing Late-Season Rangeland Grazing Systems

Animals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3219
Author(s):  
James E. Sprinkle ◽  
Joseph K. Sagers ◽  
John B. Hall ◽  
Melinda J. Ellison ◽  
Joel V. Yelich ◽  
...  
Keyword(s):  
Early Morning ◽  
Protein Supplementation ◽  
Grazing Behavior ◽  
Late Season ◽  
Bite Rate ◽  
Measured Time ◽  
Late Evening ◽  
Grazing Systems ◽  
Time Periods ◽  
Walking Time

The objective was to determine if low- or high-residual feed intake (LRFI or HRFI, n = 24 for each) Hereford × Angus cows on continuously or rotationally grazed rangeland altered their grazing behavior when provided a protein supplement in late autumn. Treatments included continuously grazed, control (CCON, n = 12); continuously grazed, supplemented (CTRT, n = 12); rotationally grazed, control (RCON, n = 12); and rotationally grazed, supplemented pastures (RTRT, n = 12). Cows in each treatment had grazing time (GT), resting time (RT), and walking time (WLK) measured for 2 years with accelerometers. Bite rate (BR) was also measured. Time distributions of GT and RT differed by year (p < 0.05), being influenced by colder temperatures in 2016. Cattle in 2016 spent more time grazing during early morning and late evening (p < 0.05) and rested more during the day (p < 0.05). In 2017, cattle in the CCON treatment walked more (p < 0.05) during early morning time periods than did the CTRT cattle, indicative of search grazing. All supplemented cattle had greater BR (p < 0.05) than control cattle in 2017. Cattle with increased nutritional demands alter grazing behavior in a compensatory fashion when grazing late-season rangelands.

scholarly journals HF-Induced Modifications of the Electron Density Profile in the Earth’s Ionosphere Using the Pump Frequencies near the Fourth Electron Gyroharmonic

2021 ◽  
Vol 13 (23) ◽  
pp. 4895
Author(s):  
Alexey V. Shindin ◽  
Evgeny N. Sergeev ◽  
Savely M. Grach ◽  
Gennady M. Milikh ◽  
Paul Bernhardt ◽  
...  
Keyword(s):  
Density Profile ◽  
Ionospheric Plasma ◽  
Pump Wave ◽  
Electromagnetic Emission ◽  
Electron Density Profile ◽  
Radio Waves ◽  
F Region ◽  
Plasma Density Profile ◽  
Hybrid Region ◽  
Hf Heating

We discuss results on plasma density profile modifications in the F-region ionosphere that are caused by HF heating with the frequency f0 in the range [(−150 kHz)–(+75 kHz)] around the fourth electron gyroharmonic 4fc. The experiments were conducted at the HAARP facility in June 2014. A multi-frequency Doppler sounder (MDS), which measures the phase and amplitude of reflected sounding radio waves, complemented by the observations of the stimulated electromagnetic emission (SEE) were used for the diagnostics of the plasma perturbations. We detected noticeable plasma expulsion from the reflection region of the pumping wave and from the upper hybrid region, where the expulsion from the latter was strongly suppressed for f0 ≈ 4fc. The plasma expulsion from the upper hybrid region was accompanied by the sounding wave’s anomalous absorption (AA) slower development for f0 ≈ 4fc. Furthermore, slower development and weaker expulsion were detected for the height region between the pump wave reflection and upper hybrid altitudes. The combined MDS and SEE allowed for establishing an interconnection between different manifestations of the HF-induced ionospheric turbulence and determining the altitude of the most effective pump wave energy input to ionospheric plasma by using the dependence on the offset between f0 and 4fc.

scholarly journals Life near a city: activity pattern of Golden Jackal Canis aureus Linnaeus, 1758 (Mammalia: Carnivora: Canidae) in a habitat adjoining Bhubaneswar, India

2021 ◽  
Vol 13 (9) ◽  
pp. 19363-19366
Author(s):  
Subrat Debata
Keyword(s):  
Activity Pattern ◽  
Prey Species ◽  
Early Morning ◽  
Golden Jackal ◽  
Eastern India ◽  
Present Study Area ◽  
Late Evening ◽  
Reduced Activity ◽  
Second Peak ◽  
Intense Heat

Activity pattern of the Golden Jackal was studied by camera trapping survey in an urban influenced protected habitat in Odisha, eastern India from January to April 2019. A total of 552 independent photos of Golden Jackals were obtained from 771 trap nights. Although Golden Jackals were active throughout the day, they showed two major peaks in activity; the first peak during late evening after sunset, and the second peak during early morning until sunrise. The reduced activity of Golden Jackal during day time in the present study area might be due to less movement of prey species, intense heat, and heavy human traffic.

Leaf Movements in Sicklepod (Cassia obtusifolia) in Relation to Herbicide Response

Weed Science ◽  
1980 ◽  
Vol 28 (5) ◽  
pp. 551-556 ◽  
Author(s):  
Gary W. Kraatz ◽  
Robert N. Andersen
Keyword(s):  
Leaf Area ◽  
Cloud Cover ◽  
Leaf Surface ◽  
Early Morning ◽  
Rhythmic Movements ◽  
Cassia Obtusifolia ◽  
Leaf Movements ◽  
Late Evening ◽  
Highly Correlated ◽  
Over The Top

Sicklepod (Cassia obtusifoliaL.) leaves and leaflets changed their orientation throughout 24-h periods. These endogenously controlled rhythmic movements resulted in dramatic changes in the percent projected leaf area (PPLA), the leaf area observed from directly above and expressed as a percentage of the total actual leaf area. The PPLA of sicklepod varied more than seven-fold throughout a 24-h period, being greatest during the day and least at night. Control of sicklepod with linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] applied postemergence at intervals throughout 24-h periods was greater from daytime applications than from late evening, night, and early morning applications. Percent control was highly correlated with PPLA, suggesting that rhythmic leaf movements and the resulting change in PPLA could be an important factor in determining the efficacy of postemergence herbicide applications on sicklepod by altering the area of the leaf surface most likely to intercept and retain herbicide spray from an over-the-top application. In addition to endogenously controlled leaf movements, we observed leaf movements caused by simulated cloud cover (80% shading). Shading increased the PPLA of sicklepod, suggesting that more leaf surface might be exposed to an over-the-top spray during cloudy periods than during sunny periods.

Diurnal gross photosynthetic patterns and potential seasonal CO2 assimilation in Cladonia stellaris and Cladonia rangiferina

1983 ◽  
Vol 61 (3) ◽  
pp. 642-655 ◽  
Author(s):  
Thomas J. Moser ◽  
Thomas H. Nash III ◽  
Steven O. Link
Keyword(s):  
Photosynthetic Activity ◽  
Growing Season ◽  
Early Morning ◽  
Co2 Assimilation ◽  
Atmospheric Moisture ◽  
Growing Seasons ◽  
Late Evening ◽  
Summer Rain ◽  
Cladonia Rangiferina

The daily, in situ gross photosynthetic patterns of Cladonia stellaris (Opiz.) Pouz. & Vězda. and Cladonia rangiferina (L.) Wigg. were monitored during portions of the 1977, 1978, and 1979 growing seasons at Anaktuvuk Pass, Alaska. Photosynthetic activity in both species closely paralleled atmospheric moisture status, where peak photosynthetic rates were attained during or following sporadic summer rain. In addition, thallus absorption of moisture during extended periods of high atmospheric water vapor content gave rise to short periods of minimal photosynthetic activity. During late evening and early morning hours moistened thalli exhibited minimal or no photosynthetic activity, coinciding with consistent attenuation in solar radiation during these periods. Photosynthetic activity was not homogeneous throughout the thallus. The greatest activity occurred in the apical regions and decreased progressively into the basal regions. The apical 10-mm regions of C. stellaris and C. rangiferina thalli accounted for approximately 50% of their photosynthetic capabilities. The potential gross CO2 assimilation of the apical 10-mm regions over 72 days of the 1978 growing season was estimated at approximately 35 g CO2∙m−2 and 16 g CO2∙m−2 for C. stellaris and C. rangiferina, respectively.

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