Binod Adhikari | Instituto Nacional de Pesquisas Espaciais (original) (raw)

Papers by Binod Adhikari

Mid-term report about recent activities and future works of the Join Study Group 1: Coupling proc... more Mid-term report about recent activities and future works of the Join Study Group 1: Coupling processes between magnetosphere, thermosphere, and ionosphere. This group is implemented at the International Association of Geodesy (IAG) Inter-Commission Committee on Theory (ICCT); joint with IAG Global Geodetic Observing System (GGOS), Focus Area on Geodetic Space Weather Research (FA-GSWR), and IAG Commission 4, and IAG subCommission 4.3.

Russian Journal of Earth Sciences, 2019

We have analyzed the trend of solar, interplanetary, and geomagnetic (SIG) parameters during sola... more We have analyzed the trend of solar, interplanetary, and geomagnetic (SIG) parameters during solar cycles 22, 23, and 24. The sunspot numbers (), solar flux index (10.7) and Lyman Alpha () indicate periodic trend during each solar cycle. In solar cycle 24 sunspot numbers (), 10.7 , and show periodic nature, but their peak is low. However, polar cap index (PCI) has maximum value in the latest solar cycle. We found a positive correlation between PCI and polar cap voltage (PCV). This means, during this period, there is a big difference between the maximum and minimum electronic convection potential in the ionosphere. In the solar cycle 24, Sun polar fields had low magnitude compared to cycle 22 and 23. This low solar polar field corresponds to the highest difference between electronic convection potentials. The same low solar polar field also corresponds to low values in , 10.7 , and. Through continuous wavelet transform (CWT), we found that solar flux, sunspot number, Lyman Alpha all have highest spectral variability from 0 to 100 months. Sunspot number, Lyman Alpha, 10.7 all have a continuous spectral energy of medium and low magnitude. We suggest that these unique condition of SIG parameters have originated from solar activity.

Earth and Space Science, 2018

Polar cap potential (PCV) is an important parameter used for determining what kind of interaction... more Polar cap potential (PCV) is an important parameter used for determining what kind of interaction takes place between solar wind and magnetosphere. Highly energetic particles from Sun driven by solar wind constantly bombard with Earth's magnetosphere-ionosphere system that results into a phenomenon like auroras, and major geomagnetic disturbances. Solar wind electron deposition determines the magnitude of field-aligned current (FAC) and ultimately leads to PCV variation. Several studies found that increase in magnitude of IMF-B z causes an electric field of cross magnetosphere to increase, and it leads to increase in magnitude of ionospheric cross-polar cap potential (PCV). Moreover, PCV was found to be a linear function of V sw. In this research, we aim to study how field-aligned current (FAC), for example, region 1 current and PCV, is related during different forms of geomagnetic disturbances. In all events, FAC and PCV are found to have corresponding fluctuations-especially at times of significant variation of IMF-B z (negative B z interval) following the linearity of equation suggested by Moon in Moon (2012, https://doi.org/10.5140/ JASS.2012.29.3.259). We found one-to-one correspondence between FAC and PCV. We did CWT analysis and found that FAC and PCV have more or less same spectral behaviors for each event considered. The crosscorrelation analysis shows a high and positive correlation between FAC and PCV at 0-min time lag for all geomagnetic activity. The CWT analysis clearly supports the result of cross correlation between FAC and PCV. We found that FAC and V sw , FAC-B, and FAC and AE are also positively correlated with high-correlation coefficient at lag 0 min for all geomagnetic storm. However, FAC-B z , FAC-B y , and FAC-SYM (H) have varying correlation in different events. For a particular storm and substorm, the parameters B z and B y may not necessarily be varied with FAC in regular sequence but IMF (B) always show positive correlation with FAC for all geomagnetic activity. This paper presents a clear relation between FAC and PCV. This result will help to identify some of the outstanding issues in determining the causal mechanism of PCV variation, a crucial thing to understanding the coupling between the solar wind and M-I system. ADHIKARI ET AL.

BIBECHANA

The comparative study of aerosol optical properties at different tourist places of Nepal has been... more The comparative study of aerosol optical properties at different tourist places of Nepal has been performed. Langtang BC, Lumbini, Pokhara, Kathmandu-bode, EVK2-CNR, Jomsom and Kyanjin_Gompa were the places chosen for observation. We have analyzed the monthly and seasonal variation of aerosol optical properties for a different year of the above-mentioned places. AOD was found to be maximum in spring due to vegetation fire and land clearing for crop cultivation and, then in winter due to biomass burning, heating needs, pollution from bricks kilns, factories, and vehicles that contribute to winter haze. It consequently decreases in summer and was found to be minimum in autumn as summer constituent both dry and wet days and autumn starts with the ending of monsoon. But it was quite different in the case of Pokhara where it was minimum in summer than in autumn as Pokhara is the only city where maximum rainfall occurs in summer. We have also studied the relation between AOD and the corre...

The present study analyses the variations in the ionospheric total electron content (TEC) prior t... more The present study analyses the variations in the ionospheric total electron content (TEC) prior to and during the 2015 Gorkha Earthquake in Nepal (Mw = 7.8) on 25 April 2015, utilising data from the widely distributed Global Positioning System (GPS) network. This study aimed to determine the association between ionospheric TEC anomalies and the occurrence of earthquakes. The finding shows that anomalous TEC changes occurred several days to a few hours prior to the major impending events. The results reveal that deviations in vertical total electron content (VTEC) at distant locations from the epicentre are less than those observed at the epicentre, implying that variation in ionospheric VTEC is nearly inversely proportional to the distance of GPS stations from the epicentre. In view of the solar-terrestrial environment, the pre-earthquake ionospheric anomalies could be associated with the 2015 Gorkha Earthquake. The VTEC anomaly was identified when it crosses the upper bound (UB) or...

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

This paper study variability of three ionospheric parameters foF2, h′F and hmF2 to investigate th... more This paper study variability of three ionospheric parameters foF2, h′F and hmF2 to investigate the middle latitude ionospheric effect at Boulder, Colorado, USA (40°N, l105.0° W) during super substorms (SSSs) of 24 August 2005, and 7 September 2017 and 8 September 2017 respectively. Continuous wavelet transform (cwt) implemented to identify the low and high frequency and longer and shorter duration present in the signal. The result shows decrease in foF2 during SSSs of 24 August 2005 and 8 September 2017 and increase in foF2 during 7 September 2017. The highest fluctuation in h′F is noticed during SSS of 24 August 2005. The cwt shows that the coupling between solar wind and magnetosphere occurs between ~ 16 to 32 minutes for SSS of 24 August 2005 and between 27.9 to 64 minutes during super substorm of 7 and 8 September 2017 for all the ionospheric parameters respectively. This study leads to understand the impact of SSSs on communication signals due to energy injected in ionosphere d...

Total Electron Content (TEC) and electron density are the basic parameters, which determine the m... more Total Electron Content (TEC) and electron density are the basic parameters, which determine the major properties of the Ionosphere. Detail study of the ionospheric TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (24°W-14°W, 25°S-10°S); (53°W46°W, 04°N-14°N); (161°E-165°E, 42°S-34°S), and (135°W120°W, 39°S-35°S) using the COSMIC satellite data. In order to find the background conditions of the ionosphere, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma velocity (Vsw), AE, Dst and Kp indices, have also been correlated with the TEC and electron density. The results illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes as well. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar act...

We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different natu... more We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different nature and strength, using ground-based CR measurements from the World Neutron Monitoring Stations Network. We took account of interplanetary triggers and the geo-effectiveness while choosing the events. Forbush Decrease (FD) was observed when the magnetic fields entangled in and around CME exerts a shielding effect on galactic cosmic radiation, causing a sudden reduction of count rate in the neutron monitors. The results revealed that the FD plunged between -4% and -20% in the chosen events. The FD examined was abnormal and a multi-stage decrement in FD was observed during the event period. The reduction in Cosmic ray intensity was found to be inversely proportional to the cut - off rigidity at the specified neutron monitoring stations. Furthermore, we have also used the Discrete Wavelet Transform (DWT) technique to detect singularity on Forbush decrease at the stations described. The first...

On 26 th December 2019, during morning hours, an annular solar eclipse having a magnitude of 0.96... more On 26 th December 2019, during morning hours, an annular solar eclipse having a magnitude of 0.96 with a 118 km wide antumbra occurred and lasted for 3 minutes and 40 seconds at the point of maximum eclipse. The partial eclipse was visible in most of Asia, parts of North/East Africa, and North/West Australia. In the context of Nepal, only the partial eclipse was visible from ~ 8:34 LT (02:51 UT) and ended at ~ 11:40 LT (05:55 UT). It was 2 hours 47 mins and 54 secs long with the maximum visible eclipse time at ~ 10:01 LT (04:16 UT). Our study is based on Global Navigation Satellite System (GNSS) measurements from a widely distributed Global Positioning System (GPS) network over different places of Nepal on the day of the eclipse, a day before, and a day after the eclipse. We investigated the ionospheric behavior through the changes in Total Electron Content (TEC) during the partial eclipse by using the data archived at the five different GPS stations of Nepal. The result reveals tha...

Article Info The Standard Big Bang Cosmology gives the most accepted concept about the beginning ... more Article Info The Standard Big Bang Cosmology gives the most accepted concept about the beginning and evolution of the Universe. However, it has problems: the flatness problem, the horizon problem and the monopole problem. The predictions of the Standard Big Bang Cosmology do not match the observations of modern cosmologists. Nonetheless, the admirers of the Standard Big Bang Cosmology continued to find out ways for solving those problems and such attempts lead to our knowledge of Inflationary Cosmology. The theory of inflation, which was first proposed by Alan Guth in 1981, soon became a “need” of modern cosmology and various modified models of inflationary Universe were proposed. In this paper, the author gives a brief insight of the Standard Big Bang Cosmology, introduces inflationary cosmology with its brief background, reviews some concepts associated with cosmic inflation, explains how inflation can be classified into various types, describes few of the popular types in brief a...

The Geostationary Operational Environmental Satellites (GOES) have been monitoring the Earth'... more The Geostationary Operational Environmental Satellites (GOES) have been monitoring the Earth's radiation environment and is providing the electron flux data (of energy >0.8 MeV, >2 MeV, and >4 MeV) by means of a connected sensor subsystem. Relativistic electron flux is one of the components of the radiation belt which not only affects the electrical system in satellites but also has an impact on Earth’s upper atmospheric climatic variation. We have carried out a study to determine the relation of sunspot number (R), solar flux (F10.7), and solar wind parameters i.e., solar wind velocity (Vsw), plasma density Nsw), the southern component of the interplanetary magnetic field (IMF-Bz), Plasma temperature (Tsw) with relativistic electron flux of energy >0.8 MeV, >2 MeV, and >4 MeV in outer radiation belt using the data of 24 years (1996-2020) covering solar cycle 23 and 24. Time series analysis, Cross-correlation and wavelet analysis techniques have been used in th...

Abstract. In this study, we analyse the climatology of ionosphere over Nepal based on GPS-derived... more Abstract. In this study, we analyse the climatology of ionosphere over Nepal based on GPS-derived vertical total electron content (VTEC) observed from four stations as defined in Table 1: KKN4 (27.80∘ N, 85.27∘ E), GRHI (27.95∘ N, 82.49∘ E), JMSM (28.80∘ N, 83.74∘ E) and DLPA (28.98∘ N, 82.81∘ E) during the years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations in VTEC during all times of solar cycle 24. The results clearly reveal the presence of equinoctial asymmetry in TEC, which is more pronounced in maximum phases of solar cycle in the year 2014 at KKN4 station, followed by descending, ascending and minimum phases. Diurnal variations in VTEC showed the short-lived day minimum which occurs between 05:00 to 06:00 LT (local time) at all the stations considered, with diurnal peaks between 12:00 and 15:00 LT. The maximum value of TEC is observed more often during the spring equinox than the autumn equinox, with a few asymmetries. S...

viXra, 2017

The Universe has a flat geometry and its density is very close to critical density. However, the ... more The Universe has a flat geometry and its density is very close to critical density. However, the observed amount of matter accounts for only 5% of the critical density. The rest of the 95% is completely unknown to us which exists in the form of Dark Energy (68%) and Dark Matter (27%). We present an overview of how the very idea of the existence of Dark Matter emerged and some compelling evidences for the existence of such matter. Moreover, we also provide an insight on how scientific ideas have evolved from a static Universe to an expanding Universe and then to an accelerating Universe. In addition, we explain fundamental concepts related to Dark Energy and discuss briefly on the evidences of Dark Energy. We also discuss some alternative solutions to the problems of Dark Matter and Dark Energy provided by different scientists.

Total Electron Content (TEC) and electron density are the basic parameters, which determine the m... more Total Electron Content (TEC) and electron density are the basic parameters, which determine the major properties of the Ionosphere. Detail study of the ionospheric TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (24{\deg}W-14{\deg}W, 25{\deg}S-10{\deg}S); (53{\deg}W- 46{\deg}W, 04{\deg}N-14{\deg}N); (161{\deg}E-165{\deg}E, 42{\deg}S-34{\deg}S), and (135{\deg}W- 120{\deg}W, 39{\deg}S-35{\deg}S) using the COSMIC satellite data. In order to find the background conditions of the ionosphere, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma velocity (Vsw), AE, Dst and Kp indices, have also been correlated with the TEC and electron density. The results illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes as well. This study illustrates that the values of TEC and the vertical electron d...

105 Wavelet and cross correlation analysis on some climatology parameters of Nepal Babu Ram Tiwar... more 105 Wavelet and cross correlation analysis on some climatology parameters of Nepal Babu Ram Tiwari1*, Jiyao Xu1, Binod Adhikari2, Narayan P. Chapagain3 1State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China100190 2Department of Physics, St. Xavier’s College, Maitighar , Kathmandu, Nepal 3Department of Physics, Amrit Campus, Tribhuvan University, Kathmandu, Nepal Email: tiwari.baburam@gmail.com

The outbreak of the COVID-19 pandemic and the subsequent global economic shutdown provided an opp... more The outbreak of the COVID-19 pandemic and the subsequent global economic shutdown provided an opportunity to conduct a real-time experiment assessing the influence of global emission reductions in the Aerosol Optical Depth (AOD) level, an indicator of air pollution over Nepal. Nepal's government imposed a lockdown on the country for approximately three months (from 24 March onwards) in 2020. The purpose of this study is to examine the temporal fluctuation in Aerosol Optical Depth (AOD) caused by the COVID-19 shutdown by comparing its value during the same time period of the past year over two sites: Pokhara and Kyanjin Gompa. We comparatively analyzed the variation of diurnal mean and monthly average AOD of two selected sites, from the month of January to May 2020 and January to May 2018. By examining the time-series graph of daily average AOD prior to and during the lockdown period, our study showed an apparent fluctuation in AOD throughout the studied areas. The major findings...

Russian Journal of Earth Sciences

Mid-term report about recent activities and future works of the Join Study Group 1: Coupling proc... more Mid-term report about recent activities and future works of the Join Study Group 1: Coupling processes between magnetosphere, thermosphere, and ionosphere. This group is implemented at the International Association of Geodesy (IAG) Inter-Commission Committee on Theory (ICCT); joint with IAG Global Geodetic Observing System (GGOS), Focus Area on Geodetic Space Weather Research (FA-GSWR), and IAG Commission 4, and IAG subCommission 4.3.

Russian Journal of Earth Sciences, 2019

We have analyzed the trend of solar, interplanetary, and geomagnetic (SIG) parameters during sola... more We have analyzed the trend of solar, interplanetary, and geomagnetic (SIG) parameters during solar cycles 22, 23, and 24. The sunspot numbers (), solar flux index (10.7) and Lyman Alpha () indicate periodic trend during each solar cycle. In solar cycle 24 sunspot numbers (), 10.7 , and show periodic nature, but their peak is low. However, polar cap index (PCI) has maximum value in the latest solar cycle. We found a positive correlation between PCI and polar cap voltage (PCV). This means, during this period, there is a big difference between the maximum and minimum electronic convection potential in the ionosphere. In the solar cycle 24, Sun polar fields had low magnitude compared to cycle 22 and 23. This low solar polar field corresponds to the highest difference between electronic convection potentials. The same low solar polar field also corresponds to low values in , 10.7 , and. Through continuous wavelet transform (CWT), we found that solar flux, sunspot number, Lyman Alpha all have highest spectral variability from 0 to 100 months. Sunspot number, Lyman Alpha, 10.7 all have a continuous spectral energy of medium and low magnitude. We suggest that these unique condition of SIG parameters have originated from solar activity.

Earth and Space Science, 2018

Polar cap potential (PCV) is an important parameter used for determining what kind of interaction... more Polar cap potential (PCV) is an important parameter used for determining what kind of interaction takes place between solar wind and magnetosphere. Highly energetic particles from Sun driven by solar wind constantly bombard with Earth's magnetosphere-ionosphere system that results into a phenomenon like auroras, and major geomagnetic disturbances. Solar wind electron deposition determines the magnitude of field-aligned current (FAC) and ultimately leads to PCV variation. Several studies found that increase in magnitude of IMF-B z causes an electric field of cross magnetosphere to increase, and it leads to increase in magnitude of ionospheric cross-polar cap potential (PCV). Moreover, PCV was found to be a linear function of V sw. In this research, we aim to study how field-aligned current (FAC), for example, region 1 current and PCV, is related during different forms of geomagnetic disturbances. In all events, FAC and PCV are found to have corresponding fluctuations-especially at times of significant variation of IMF-B z (negative B z interval) following the linearity of equation suggested by Moon in Moon (2012, https://doi.org/10.5140/ JASS.2012.29.3.259). We found one-to-one correspondence between FAC and PCV. We did CWT analysis and found that FAC and PCV have more or less same spectral behaviors for each event considered. The crosscorrelation analysis shows a high and positive correlation between FAC and PCV at 0-min time lag for all geomagnetic activity. The CWT analysis clearly supports the result of cross correlation between FAC and PCV. We found that FAC and V sw , FAC-B, and FAC and AE are also positively correlated with high-correlation coefficient at lag 0 min for all geomagnetic storm. However, FAC-B z , FAC-B y , and FAC-SYM (H) have varying correlation in different events. For a particular storm and substorm, the parameters B z and B y may not necessarily be varied with FAC in regular sequence but IMF (B) always show positive correlation with FAC for all geomagnetic activity. This paper presents a clear relation between FAC and PCV. This result will help to identify some of the outstanding issues in determining the causal mechanism of PCV variation, a crucial thing to understanding the coupling between the solar wind and M-I system. ADHIKARI ET AL.

BIBECHANA

The comparative study of aerosol optical properties at different tourist places of Nepal has been... more The comparative study of aerosol optical properties at different tourist places of Nepal has been performed. Langtang BC, Lumbini, Pokhara, Kathmandu-bode, EVK2-CNR, Jomsom and Kyanjin_Gompa were the places chosen for observation. We have analyzed the monthly and seasonal variation of aerosol optical properties for a different year of the above-mentioned places. AOD was found to be maximum in spring due to vegetation fire and land clearing for crop cultivation and, then in winter due to biomass burning, heating needs, pollution from bricks kilns, factories, and vehicles that contribute to winter haze. It consequently decreases in summer and was found to be minimum in autumn as summer constituent both dry and wet days and autumn starts with the ending of monsoon. But it was quite different in the case of Pokhara where it was minimum in summer than in autumn as Pokhara is the only city where maximum rainfall occurs in summer. We have also studied the relation between AOD and the corre...

The present study analyses the variations in the ionospheric total electron content (TEC) prior t... more The present study analyses the variations in the ionospheric total electron content (TEC) prior to and during the 2015 Gorkha Earthquake in Nepal (Mw = 7.8) on 25 April 2015, utilising data from the widely distributed Global Positioning System (GPS) network. This study aimed to determine the association between ionospheric TEC anomalies and the occurrence of earthquakes. The finding shows that anomalous TEC changes occurred several days to a few hours prior to the major impending events. The results reveal that deviations in vertical total electron content (VTEC) at distant locations from the epicentre are less than those observed at the epicentre, implying that variation in ionospheric VTEC is nearly inversely proportional to the distance of GPS stations from the epicentre. In view of the solar-terrestrial environment, the pre-earthquake ionospheric anomalies could be associated with the 2015 Gorkha Earthquake. The VTEC anomaly was identified when it crosses the upper bound (UB) or...

IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

This paper study variability of three ionospheric parameters foF2, h′F and hmF2 to investigate th... more This paper study variability of three ionospheric parameters foF2, h′F and hmF2 to investigate the middle latitude ionospheric effect at Boulder, Colorado, USA (40°N, l105.0° W) during super substorms (SSSs) of 24 August 2005, and 7 September 2017 and 8 September 2017 respectively. Continuous wavelet transform (cwt) implemented to identify the low and high frequency and longer and shorter duration present in the signal. The result shows decrease in foF2 during SSSs of 24 August 2005 and 8 September 2017 and increase in foF2 during 7 September 2017. The highest fluctuation in h′F is noticed during SSS of 24 August 2005. The cwt shows that the coupling between solar wind and magnetosphere occurs between ~ 16 to 32 minutes for SSS of 24 August 2005 and between 27.9 to 64 minutes during super substorm of 7 and 8 September 2017 for all the ionospheric parameters respectively. This study leads to understand the impact of SSSs on communication signals due to energy injected in ionosphere d...

Total Electron Content (TEC) and electron density are the basic parameters, which determine the m... more Total Electron Content (TEC) and electron density are the basic parameters, which determine the major properties of the Ionosphere. Detail study of the ionospheric TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (24°W-14°W, 25°S-10°S); (53°W46°W, 04°N-14°N); (161°E-165°E, 42°S-34°S), and (135°W120°W, 39°S-35°S) using the COSMIC satellite data. In order to find the background conditions of the ionosphere, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma velocity (Vsw), AE, Dst and Kp indices, have also been correlated with the TEC and electron density. The results illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes as well. This study illustrates that the values of TEC and the vertical electron density profile are influenced by the solar wind parameters associated with solar act...

We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different natu... more We analyzed the behavior of Cosmic Ray (CR) intensity during geomagnetic events of different nature and strength, using ground-based CR measurements from the World Neutron Monitoring Stations Network. We took account of interplanetary triggers and the geo-effectiveness while choosing the events. Forbush Decrease (FD) was observed when the magnetic fields entangled in and around CME exerts a shielding effect on galactic cosmic radiation, causing a sudden reduction of count rate in the neutron monitors. The results revealed that the FD plunged between -4% and -20% in the chosen events. The FD examined was abnormal and a multi-stage decrement in FD was observed during the event period. The reduction in Cosmic ray intensity was found to be inversely proportional to the cut - off rigidity at the specified neutron monitoring stations. Furthermore, we have also used the Discrete Wavelet Transform (DWT) technique to detect singularity on Forbush decrease at the stations described. The first...

On 26 th December 2019, during morning hours, an annular solar eclipse having a magnitude of 0.96... more On 26 th December 2019, during morning hours, an annular solar eclipse having a magnitude of 0.96 with a 118 km wide antumbra occurred and lasted for 3 minutes and 40 seconds at the point of maximum eclipse. The partial eclipse was visible in most of Asia, parts of North/East Africa, and North/West Australia. In the context of Nepal, only the partial eclipse was visible from ~ 8:34 LT (02:51 UT) and ended at ~ 11:40 LT (05:55 UT). It was 2 hours 47 mins and 54 secs long with the maximum visible eclipse time at ~ 10:01 LT (04:16 UT). Our study is based on Global Navigation Satellite System (GNSS) measurements from a widely distributed Global Positioning System (GPS) network over different places of Nepal on the day of the eclipse, a day before, and a day after the eclipse. We investigated the ionospheric behavior through the changes in Total Electron Content (TEC) during the partial eclipse by using the data archived at the five different GPS stations of Nepal. The result reveals tha...

Article Info The Standard Big Bang Cosmology gives the most accepted concept about the beginning ... more Article Info The Standard Big Bang Cosmology gives the most accepted concept about the beginning and evolution of the Universe. However, it has problems: the flatness problem, the horizon problem and the monopole problem. The predictions of the Standard Big Bang Cosmology do not match the observations of modern cosmologists. Nonetheless, the admirers of the Standard Big Bang Cosmology continued to find out ways for solving those problems and such attempts lead to our knowledge of Inflationary Cosmology. The theory of inflation, which was first proposed by Alan Guth in 1981, soon became a “need” of modern cosmology and various modified models of inflationary Universe were proposed. In this paper, the author gives a brief insight of the Standard Big Bang Cosmology, introduces inflationary cosmology with its brief background, reviews some concepts associated with cosmic inflation, explains how inflation can be classified into various types, describes few of the popular types in brief a...

The Geostationary Operational Environmental Satellites (GOES) have been monitoring the Earth'... more The Geostationary Operational Environmental Satellites (GOES) have been monitoring the Earth's radiation environment and is providing the electron flux data (of energy >0.8 MeV, >2 MeV, and >4 MeV) by means of a connected sensor subsystem. Relativistic electron flux is one of the components of the radiation belt which not only affects the electrical system in satellites but also has an impact on Earth’s upper atmospheric climatic variation. We have carried out a study to determine the relation of sunspot number (R), solar flux (F10.7), and solar wind parameters i.e., solar wind velocity (Vsw), plasma density Nsw), the southern component of the interplanetary magnetic field (IMF-Bz), Plasma temperature (Tsw) with relativistic electron flux of energy >0.8 MeV, >2 MeV, and >4 MeV in outer radiation belt using the data of 24 years (1996-2020) covering solar cycle 23 and 24. Time series analysis, Cross-correlation and wavelet analysis techniques have been used in th...

Abstract. In this study, we analyse the climatology of ionosphere over Nepal based on GPS-derived... more Abstract. In this study, we analyse the climatology of ionosphere over Nepal based on GPS-derived vertical total electron content (VTEC) observed from four stations as defined in Table 1: KKN4 (27.80∘ N, 85.27∘ E), GRHI (27.95∘ N, 82.49∘ E), JMSM (28.80∘ N, 83.74∘ E) and DLPA (28.98∘ N, 82.81∘ E) during the years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations in VTEC during all times of solar cycle 24. The results clearly reveal the presence of equinoctial asymmetry in TEC, which is more pronounced in maximum phases of solar cycle in the year 2014 at KKN4 station, followed by descending, ascending and minimum phases. Diurnal variations in VTEC showed the short-lived day minimum which occurs between 05:00 to 06:00 LT (local time) at all the stations considered, with diurnal peaks between 12:00 and 15:00 LT. The maximum value of TEC is observed more often during the spring equinox than the autumn equinox, with a few asymmetries. S...

viXra, 2017

The Universe has a flat geometry and its density is very close to critical density. However, the ... more The Universe has a flat geometry and its density is very close to critical density. However, the observed amount of matter accounts for only 5% of the critical density. The rest of the 95% is completely unknown to us which exists in the form of Dark Energy (68%) and Dark Matter (27%). We present an overview of how the very idea of the existence of Dark Matter emerged and some compelling evidences for the existence of such matter. Moreover, we also provide an insight on how scientific ideas have evolved from a static Universe to an expanding Universe and then to an accelerating Universe. In addition, we explain fundamental concepts related to Dark Energy and discuss briefly on the evidences of Dark Energy. We also discuss some alternative solutions to the problems of Dark Matter and Dark Energy provided by different scientists.

Total Electron Content (TEC) and electron density are the basic parameters, which determine the m... more Total Electron Content (TEC) and electron density are the basic parameters, which determine the major properties of the Ionosphere. Detail study of the ionospheric TEC and electron density variations has been carried out during geomagnetic storms, with longitude and latitude, for four different locations: (24{\deg}W-14{\deg}W, 25{\deg}S-10{\deg}S); (53{\deg}W- 46{\deg}W, 04{\deg}N-14{\deg}N); (161{\deg}E-165{\deg}E, 42{\deg}S-34{\deg}S), and (135{\deg}W- 120{\deg}W, 39{\deg}S-35{\deg}S) using the COSMIC satellite data. In order to find the background conditions of the ionosphere, the solar wind parameters such as north-south component of inter planetary magnetic field (Bz), plasma velocity (Vsw), AE, Dst and Kp indices, have also been correlated with the TEC and electron density. The results illustrates that the observed TEC and electron density profile significantly vary with longitudes and latitudes as well. This study illustrates that the values of TEC and the vertical electron d...

105 Wavelet and cross correlation analysis on some climatology parameters of Nepal Babu Ram Tiwar... more 105 Wavelet and cross correlation analysis on some climatology parameters of Nepal Babu Ram Tiwari1*, Jiyao Xu1, Binod Adhikari2, Narayan P. Chapagain3 1State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, China100190 2Department of Physics, St. Xavier’s College, Maitighar , Kathmandu, Nepal 3Department of Physics, Amrit Campus, Tribhuvan University, Kathmandu, Nepal Email: tiwari.baburam@gmail.com

The outbreak of the COVID-19 pandemic and the subsequent global economic shutdown provided an opp... more The outbreak of the COVID-19 pandemic and the subsequent global economic shutdown provided an opportunity to conduct a real-time experiment assessing the influence of global emission reductions in the Aerosol Optical Depth (AOD) level, an indicator of air pollution over Nepal. Nepal's government imposed a lockdown on the country for approximately three months (from 24 March onwards) in 2020. The purpose of this study is to examine the temporal fluctuation in Aerosol Optical Depth (AOD) caused by the COVID-19 shutdown by comparing its value during the same time period of the past year over two sites: Pokhara and Kyanjin Gompa. We comparatively analyzed the variation of diurnal mean and monthly average AOD of two selected sites, from the month of January to May 2020 and January to May 2018. By examining the time-series graph of daily average AOD prior to and during the lockdown period, our study showed an apparent fluctuation in AOD throughout the studied areas. The major findings...

Russian Journal of Earth Sciences