Cosmic ray intensity increases during high solar activity period for the solar cycles 22 and 23

2018 ◽  
Vol 93 (2) ◽  
pp. 139-145 ◽  
Author(s):  
Sham Singh ◽  
A. P. Mishra
Keyword(s):  
Solar Activity ◽  
Cosmic Ray ◽  
Activity Period ◽  
High Solar Activity ◽  
Solar Cycles ◽  
Cosmic Ray Intensity ◽  
Solar Activity Period

scholarly journals Comparison of IRI-2016 model with IGS VTEC maps during low and high solar activity period

2019 ◽  
Vol 12 ◽  
pp. 555-561 ◽  
Author(s):  
Chuang Shi ◽  
Tao Zhang ◽  
Cheng Wang ◽  
Zhipeng Wang ◽  
Lei Fan
Keyword(s):  
Solar Activity ◽  
Activity Period ◽  
High Solar Activity ◽  
Solar Activity Period

scholarly journals Evaluating the Performance of IRI-2016 Using GPS-TEC Measurements over the Equatorial Region

Atmosphere ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1243
Author(s):  
Nouf Abd Elmunim ◽  
Mardina Abdullah ◽  
Siti Aminah Bahari
Keyword(s):  
Solar Activity ◽  
Early Morning ◽  
Equatorial Region ◽  
Activity Period ◽  
High Solar Activity ◽  
Electron Content ◽  
Dual Frequency ◽  
Iri Model ◽  
Total Electron ◽  
Solar Activity Period

Total electron content (TEC) is an important parameter in the ionosphere that is extensively used to study the variability of the ionosphere as it significantly affects radio wave propagations, causing delays on GPS signals. Therefore, evaluating the performance of ionospheric models is crucial to reveal the variety of ionospheric behaviour in different solar activity periods during geomagnetically quiet and disturbed periods for further improvements of the IRI model performance over the equatorial region. This research aimed to investigate the variations of ionospheric VTEC and observe the improvement in the performance of the IRI-2016 (IRI-2001, IRI01-corr, and NeQuick). The IRI-2016 was evaluated with the IRI-2012 using NeQuick, IRI-2001, and IRI01-corr topside electron density options. The data were obtained using a dual-frequency GPS receiver installed at the Universiti Utara Malaysia Kedah (UUMK) (geographic coordinates 4.62° N–103.21° E, geomagnetic coordinates 5.64° N–174.98° E), Mukhtafibillah (MUKH) (geographic coordinates 6.46° N–100.50° E, geomagnetic coordinates 3.32° S–172.99° E), and Tanjung Pengerang (TGPG) (geographic coordinates 1.36° N–104.10°E, geomagnetic coordinates 8.43° S–176.53° E) stations, during ascending to high solar activity at the geomagnetically quiet and disturbed periods in October 2011, March 2012, and March 2013. The maximum hourly ionospheric VTEC was observed during the post-noon time, while the minimum was during the early morning time. The ionospheric VTEC modelled by IRI-2016 had a slight improvement from the IRI-2012. However, the differences were observed during the post-noon and night-time, while the modelled VTEC from both IRI models were almost similar during the early morning time. Regarding the daily quiet and disturbed period’s prediction capability of the IRI-2016 and IRI-2012, IRI-2016 gave better agreement with the measured VTEC. The overall results showed that the model’s prediction performance during the high solar activity period in 2013 was better than the one during the ascending solar activity period. The results of the comparison between IRI-2016 and IRI-2012 in high solar activity exhibited that during quiet periods, all the IRI models showed better agreement with the measured VTEC compared to the disturbed periods.

Thermospheric temperature during a high solar activity period

Eos ◽  
1990 ◽  
Vol 71 (39) ◽  
pp. 1100 ◽  
Author(s):  
J. S. Kim ◽  
G. S. N. Murty ◽  
J. W. Kim ◽  
Y. Kim
Keyword(s):  
Solar Activity ◽  
Activity Period ◽  
High Solar Activity ◽  
Solar Activity Period

scholarly journals Electrodynamic influence on the diurnal behaviour of neutral daytime airglow emissions

2016 ◽  
Vol 34 (11) ◽  
pp. 1019-1030 ◽  
Author(s):  
Deepak K. Karan ◽  
Duggirala Pallamraju ◽  
Kedar A. Phadke ◽  
Tatiparti Vijayalakshmi ◽  
Tarun K. Pant ◽  
...  
Keyword(s):  
Solar Activity ◽  
Electric Field ◽  
Activity Period ◽  
High Solar Activity ◽  
Intensity Measurements ◽  
Airglow Emissions ◽  
Asymmetric Behaviour ◽  
Radio Measurements ◽  
Solar Activity Period ◽  
Diurnal Behaviour

Abstract. The diurnal variations in daytime airglow emission intensity measurements at three wavelengths OI 777.4 nm, OI 630.0 nm, and OI 557.7 nm made from a low-latitude location, Hyderabad (17.5° N, 78.4° E; 8.9° N MLAT) in India have been investigated. The intensity patterns showed both symmetric and asymmetric behaviour in their respective diurnal emission variability with respect to local noon. The asymmetric diurnal behaviour is not expected considering the photochemical nature of the production mechanisms. The reason for this observed asymmetric diurnal behaviour has been found to be predominantly the temporal variation in the equatorial electrodynamics. The plasma that is transported across latitudes due to the action of varying electric field strengths over the magnetic equator in the daytime contributes to the asymmetric diurnal behaviour in the neutral daytime airglow emissions. Independent magnetic and radio measurements support this finding. It is also noted that this asymmetric diurnal behaviour in the neutral emission intensities has a solar cycle dependence with a greater number of days during high solar activity period showing asymmetric diurnal behaviour compared to those during a low solar activity epoch. These intensity variations over a long timescale demonstrate that the daytime neutral optical emissions are extremely sensitive to the changes in the eastward electric field over low and equatorial latitudes.

HIGH-ALTITUDE COSMIC RAY MEASUREMENTS AT FORT CHURCHILL

1960 ◽  
Vol 38 (5) ◽  
pp. 638-641 ◽  
Author(s):  
I. B. McDiarmid ◽  
D. C. Rose
Keyword(s):  
Solar Activity ◽  
High Altitude ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Cosmic Ray ◽  
Geiger Counter ◽  
Low Energy ◽  
High Solar Activity ◽  
Energy Radiation ◽  
Cosmic Ray Intensity

Measurements with rocket-borne Geiger counters have been carried out at altitudes up to 250 km at Fort Churchill, Manitoba. The total primary cosmic ray intensity at a time near a solar maximum has been determined and compared with other measurements taken at times of high solar activity and also with other Geiger counter measurements obtained near a solar minimum. A low-energy radiation was observed whose intensity increased with altitude up to about 25% of the primary intensity at 250 km.

scholarly journals Further tests of the IRI and DGR model ionospheres

1994 ◽  
Vol 37 (2) ◽  
Author(s):  
K. J. Kecic ◽  
P. A. Bradley ◽  
L. R. Cander ◽  
M. I. Dick ◽  
B. Zolesi
Keyword(s):  
Solar Activity ◽  
Activity Period ◽  
High Solar Activity ◽  
Small Data ◽  
Data Set ◽  
Ionospheric Models ◽  
Small Data Set ◽  
Solar Activity Period

The present study discusses and compares the IRI and DGR ionospheric models using N(h) profiles obtained during a high solar activity period at South Uist ionosonde station. After inversion, N(h) profiles obtained from ionograms at South Uist have been compared with those derived from the IRI-90 and DGR ionospheric models. A small data set has been selected such that both geomagnetically quiet and disturbed conditions are represented. The importance of further comparisons with additional sets of N(h) profiles under different solar-geophysical conditions and at more stations has been recognized.

THE VARIATION OF SEA LEVEL COSMIC RAY INTENSITY BETWEEN 1954 AND 1957

1958 ◽  
Vol 36 (7) ◽  
pp. 824-839 ◽  
Author(s):  
A. G. Fenton ◽  
D. C. Rose ◽  
K. B. Fenton
Keyword(s):  
Solar Activity ◽  
Sea Level ◽  
Geomagnetic Latitude ◽  
Cosmic Ray ◽  
High Solar Activity ◽  
General Level ◽  
Intensity Level ◽  
Cosmic Ray Intensity ◽  
Primary Cosmic Radiation ◽  
The One

Results from neutron monitors and meson telescopes at Ottawa (geomagnetic latitude 57° N.) and Resolute (geomagnetic latitude 83° N.) are presented for the years 1954–57, a period of increasing solar activity. The results indicate that the sea level meson intensity at these latitudes decreased by 5–6% between April 1954 and December 1957. During the same period the intensity of the nucleonic component at these stations decreased by over 22%. Investigation of the relative response of the two types of recorder to transient decreases during this period indicates that the long term change in the intensity level cannot be explained completely as an accumulation of shorter transient decreases, which become more frequent at times of high solar activity. It is concluded that the transient decreases are superimposed upon the longer term changes, each being produced by a separate modulation process but ultimately controlled by the general level of solar activity. Significant differences are found in the shape of transient decreases observed at the Canadian stations, both between different components at the one station and the same component at different stations. These may be interpreted as due to a varying energy dependence from one transient decrease to another, and to anisotropy in the primary cosmic radiation at these times.

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