Sentence examples for occurrence of spread from inspiring English sources

In Fig. 2, the occurrence of spread F (19 30 22 00 LT) is shown by a red solid rectangle.

Occurrence of Spread F is more or less a daily phenomenon in the equatorial and low latitudinal stations during high to moderate sunspot number years.

There seems to exist general consensus on the geomagnetic declination-, longitude- and solar- control of seasonal occurrence of spread F, whereas solar flux seems to produce superimposed effects, including the solar activity cycle in its occurrence features.

Jayachandran et al. (1993) used HF Doppler radar and ionosonde measurements to determine the height and its variation of the evening equatorial F layer, the vertical plasma drift velocity in the evening equatorial region, and the occurrence of spread F. The observations showed that, for the onset of ESF, the F layer should attain a threshold height.

Another important feature of the equatorial ionosphere is the occurrence of spread echoes in the F-region on the ionograms following the rise of the F-layer after sunset, known as the Equatorial Spread-F (ESF), and first reported by Booker and Wells (1938).

The probability of occurrence of spread-F can be modeled and predicted using neural networks (NNs).

The main objective of this paper is to present a new computational tool, based on fuzzy relation, designed to automatically identify the occurrence of Spread-F in ionograms.

Fig. 5 Dst variation and occurrence of spread-F during a multiple geomagnetic storm with first main phase on 17 April 2002.

Liu and Shen (2017) found that the disturbance of electric fields could also contribute to the occurrence of spread-Fs, especially at low-latitude stations.

The post-sunset enhancements in the vertical drift of the equatorial F-layer are also reduced significantly from their quiet day patterns and the subsequent occurrence of Spread-F and scintillations is inhibited.

This paper presents a feasibility study into the development of a NN based model for the prediction of the probability of occurrence of spread-F over selected equatorial stations within the Brazilian sector.