Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020

Uluma Edward; Chali Idosa Uga; Athwart Davis Odhiambo; Binod Adhikari; Sujan Prasad Gautam; Ndinya Boniface; Omondi George; Ashutosh Giri; Dessalegn Teferi; Negasa Belay; Ashok Silwal

doi:doi:10.11648/j.ijass.20241201.11

Research Article |

| Peer-Reviewed

Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020

Uluma Edward^*

, Chali Idosa Uga

, Athwart Davis Odhiambo

, Binod Adhikari

, Sujan Prasad Gautam

, Ndinya Boniface

, Omondi George

, Ashutosh Giri

, Dessalegn Teferi

, Negasa Belay

, Ashok Silwal

Published in International Journal of Astrophysics and Space Science (Volume 12, Issue 1)

Received: 2 May 2024 Accepted: 22 May 2024 Published: 15 July 2024

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Abstract

During sand and dust storm (SDS) events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere which plays a very important role in the atmosphere-ionosphere coupling. The Godzilla SDS began on 5^th June 2020 in Algeria following a decrease in pressure and spread to other areas across the Sahara between 6^th and 28^th June 2020. Using SDS data from Copernicus Sentinel-5P satellite mission and Vertical Total Electron Content (VTEC) data from four GNSS receiver stations: IFR1 (Ifrane Seismic), MELI (Melilla), TETN (Tetouan) and OUCA (Ouca) over Morocco, we investigate the possible ionospheric TEC variability over the four GNSS receiver stations during the Godzilla SDS event which was tracked using the Sentinel-5P Satellite mission. Solar wind parameters: Horizontal component of Interplanetary Magnetic Field (IMF-Bz), interplanetary Electric Field (IEF-Ey) and solar wind speed (V) and geomagnetic indices: Disturbance Storm Time (Dst) and Planetary K (Kp) indices were examined and showed very minimal geomagnetic influence during the period. We observed major ionospheric disturbances over the four Global Navigation Satellite System (GNSS) receiver stations on 16^th, 17^th, 18^th, 21^st, 22^nd, 23^rd 25^th and 26^th June 2020: the period with the Sentinel-5P Aerosol Index (SAI) of more than 4 as recorded by the Sentinel-5P Satellite engine. The daily VTEC values over the four GNSS receiver stations recorded continuous electron density perturbations during these days. Apart from the ionospheric TEC perturbations, significant enhancements and decreases in daily maximum VTEC values over the four GNSS receiver stations were also noted. These were attributed to the changes in the atmospheric electric fields generated by the SDS event. The VTEC plots for each day exhibited similar trends, hence exhibited the same ionospheric dynamics. VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12^th, 14^th, 17^th, 20^th and 25^th June 2020. Nighttime VTEC enhancements were also noted and majorly occurred between 20:00 and 21:00 UT on 9^th, 13^th, 15^th, 17^th, 19^th, 20^th and 21^st June 2020. This was attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. In conclusion, the Godzilla SDS of June 2020 led to the electron density perturbations over Morocco.

Published in	International Journal of Astrophysics and Space Science (Volume 12, Issue 1)
DOI	10.11648/j.ijass.20241201.11
Page(s)	1-16
Creative Commons	This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.
Copyright	Copyright © The Author(s), 2024. Published by Science Publishing Group

Keywords

Godzilla Sand and Dust Storm, Atmospheric Electric Fields, Aerosols, Vertical Total Electron Content

1. Introduction

A sand and dust storm (SDS) is a meteorological phenomenon that commonly occurs in arid and semi-arid regions. It occurs when loose sand and dust are blown over long distances from one region to another

[1]

. Between 5^th and 28^th June 2020, the Earth experienced a very thick and dense dust plume travelling over 5000 miles along the African Saharan desert towards the United States (USA) and the Caribbean and having a greater wind velocity compared to others that have ever occurred

[2]

. The dust storm was nicknamed ‘Godzilla’ due its intense impact and gravity

[3, 4]

. According to National Oceanic and Atmospheric Administration (NOAA), the Godzilla SDS is approximated to be between 60% to 70% larger than the dust storms experienced in the past

[5]

. The uprising of the Godzilla SDS took place on 5^th June 2020 in Algeria following a decrease in pressure

[4]

and spread to other areas across the Sahara between 6^th and 28^th June 2020. The background cause of this particular event still remains unclear with some hypothesis pointing at extra Earth warming which degenerated into extreme convectional currents or it being a meteorological anomaly

[6]

Download: Download full-size image

Figure 1. Model diagram of the Global Electric Circuit (GEC)

[13, 14]

The ionosphere varies with latitude, longitude, altitude, season, universal time and geomagnetic activity

[7-9]

. This ionospheric variability arises from time delays, atmosphere-ionosphere couplings and other magnetospheric, interplanetary and mesospheric processes and variations in electric fields and neutral composition

[10]

. During SDS events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere with an electric field of between 10Kv/m and 100Kv/m being observed in the terrestrial atmosphere

[11]

. This electrification process plays a very important role in the atmosphere-ionosphere coupling during the period

[12]

. Sand and dust particles flowing in the atmosphere during SDS usually modify the electric properties of the lower atmosphere, leading to creation of low conducting layers (caused by the ion-aerosol attachment) which increases column resistance for the vertical current flowing between the upper conducting layer (ionosphere) and the ground within the Global Electric Circuit (GEC) model indicated in Figure 1.

In the model diagram of the GEC, Ԑ; R_i; R_S; R_T and R_BL represent atmospheric electric fields, internal resistance of the atmospheric electric fields, resistance of the stratosphere, the resistance of the troposphere and the resistance of the atmospheric boundary layer respectively. The average potential difference at the ionosphere is about 250 kV while the average electric field gradient on the Earth’s surface is about 100V/m, with the potential difference between the ionosphere and the Earth’s surface ranging between 150 and 500 kV

[13]

. The electrical conductivity of the atmosphere provides information on the ionization processes that controls the electrical state of the atmosphere and on the major charged particle species, free electrons, positive and negative ions that are present in the medium according to the GEC

[11]

. The upper atmosphere has a higher conductivity than the lower atmosphere as a result of ionization from highly varying and energetic background source of energetic particles that bombard the Earth continuously (galactic cosmic rays)

[18]

. Conductivity of the upper atmosphere arises from presence of free electrons and ions which can readily move under impressed forces and thus act as efficient charge carriers. The electrons and ions respond differently to the impressed forces such that ion and electron currents are necessarily not the same

[15]

. In cases where the positive and negative particles move in the opposite directions, the electrons and ions are added together but in cases where the ions and electrons move exactly together, the two currents usually cancel out, hence no net current. However, in any of the two cases, the plasma as a whole is in motion, in what is known as plasma drift

[15]

. Hoppel, W. A. et al, have shown that the atmospheric boundary layer is about 75% of the total resistance of the atmospheric column between the lower ionosphere and the Earth’s surface

[16]

. Hence, the presence of aerosols in the atmosphere during SDS events increases the resistance of the atmospheric boundary layer

[17]

, leading to an increase in potential drop on the boundary layer. This results in the growth of the ionosphere potential relative to the Earth’s surface. Positive electron density anomalies are then formed in the ionosphere above the affected regions

[13, 14, 17-19]

Pulinets, S. et al, studied the atmosphere-ionosphere coupling induced by dust storms using Differential Global Ionospheric Maps (GIM) Total Electron Content (TEC) mapping procedure to show specific features of ionospheric reaction. Their results revealed positive ionospheric phenomena over the area of air pollution and over the magnetically conjugated area in low latitude and equatorial regions. They concluded that the phenomena posed double error for precise point positioning (PPP) due to sharp TEC gradients on the borders of the formed positive irregularities of electron concentration

[14]

. Tramutoli, V. et al, analyzed two Saharan dust events of May 2008 which were detected by Robust Satellite Techniques (RST) using Spinning Enhanced Visible and Infrared Imager (SEVIRI) optical data. The DETEMER and GPS-TEC showed some ionospheric perturbations over the Mediterranean basin. Generally, their study confirmed the perturbing effects of dust and volcanic events on tropospheric and ionospheric parameters

[20]

. The atmosphere-ionosphere interactions due to SDS events are unique and quite complex as they depend on the structure of the storm and various atmospheric factors. Thus further studies needs to be done to fully understand the dynamics behind it.

Examining changes in TEC during SDS events play a critical role in unraveling possible intricate relationship between these natural occurrences and the ionosphere. Although this is an open scientific problem (an on-going research) how SDS event triggers ionospheric TEC; the possible mechanism proposed are that during these storms, various elements such as sand and dust aerosols infiltrate the atmosphere, impacting electron distribution, while charged particles alter the ionosphere's electrical properties. Furthermore, the atmospheric disturbances generated by these storms influence electron density and subsequently affect TEC measurements. In this paper, we investigate and present results on the possible ionospheric TEC variability brought about by the atmospheric-ionospheric interaction during the Godzilla SDS of June 2020 over Morocco using GPS-TEC data from four Global Navigation Satellite Systems (GNSS) receiver stations: IFR1 (Ifrane Seismic), OUCA (Ouca), MELI (Melilla) and TETN (Tetouan), all situated in Morocco. We focus our study on TEC measurement using Global Positioning Satellite (GPS) receivers as it is a reliable and cost-effective method of probing the thermosphere-ionosphere system

[21]

2. Data Acquisition and Methodology

2.1. Geomagnetic Indices and Solar Wind Parameters Data

In this study we considered the period between 1^st and 30^th June 2020 which was the period in which the Godzilla SDS occurred over the Sahara. The geomagnetic indices data that show the level of the geomagnetic activity between 1^stand 30^th June 2020 were obtained using Kp index: www.kugi.kyoto-ua.ac.jp/kp and Dst index: wdc.kugi.kyoto.u.ac.jp/dst/index.html. The daily values of solar wind parameters such as interplanetary magnetic field (IMF-Bz), interplanetary electric field (IEF-Ey) and solar wind speed (V) were obtained from: https://omniweb.gsfc.nasa.gov/form/dx1.html.

2.2. IGS Data

In this study, the GPS-TEC data over four stations whose Geomagnetic coordinates are: IFR1 (33.51393°N, 354.8748°E); MELI (35.28119°N, 357.048°E); OUCA (31.20659°N, 352.13349°E) and TETN (35.56165°N, 354.63699°E) in Morocco was accessed from the University of NAVSTAR Consortium dual frequency devices (http://unavco.org/data/gps-gnss/data-access methods/dai1/dai1.html). GPS-TEC data in the IGS receivers is saved in the zipped Receiver Independent Exchange (RINEX) Format and then adapted to GPS observable files with the use of appropriate software

[22]

. These GPS measurements are either code pseudoranges (P) or carrier phases (ϕ). The receiver receives the code time delay and carrier phase difference by cross-correlating the f₁ and f₂ modulated carrier signals, which are normally considered to travel along the same path through the ionosphere

[23]

. It is acceptable to obtain estimates of GPS-derived ionospheric TEC using dual frequency GPS measurements

[24, 25]

. GPS receiver data are critical for estimating the electron density along a ray path between a GPS satellite and a ground receiver

[26, 27]

. Dual-frequency GPS receivers may offer integral information on the ionosphere and plasmasphere by computing the differential of the code and carrier phase measurements, in addition to removing ionospheric inaccuracies in TEC estimates

[28, 29]

. As a result, the GPS-TEC computed by the dual-frequency receivers is offered as an input to an ionosphere assimilation model

[30]

. For the present study, GPS data collected in dual-frequency receivers was used, and GPS-TEC data was obtained using the pseudo-range and carrier phase measurements. The TEC calculated from the pseudo-range measurement (slant TEC) is given by the following Equation 1:

(1)

Similarly, the TEC from carrier phase measurement may be calculated as follows using Equation 2:

(2)

where f₁ and f₂ are GPS satellite frequencies determined from the fundamental frequency, f_o=10.23MHz as: (f₁=154, f_o=1,575.42MHz), (f₂=120, f_o=1,227.60 MHz), and the differential code and phase measurements are (P₂ – P₁) and (ϕ₁ – ϕ₂), respectively

[31]

. The vertical total electron content (VTEC) is obtained using the relations in electrons per metre square using Equation 3:

(3)

where the zenith angle

is given by Equation 4:

(4)

VTEC is therefore given by equation 5:

(5)

Where α is the satellite’s elevation angle, R_E is the Earth’s mean radius, and h is the height of the ionospheric layer, which is considered to be 400 km.

To reduce multipath effects, the data selected was for elevation angles of 30° and above

[32]

Information for the four GNSS receiver stations: MELI, IFR1, OUCA and TETN is given in Table 1:

Table 1. Information of the geographical and geomagnetic locations of the stations over Morocco.

Station ID	Station Name	Geographic Latitude	Geographic Longitude	Geomagnetic Latitude	Geomagnetic Longitude	Local Time
MELI	Melilla	35.28°N	-2.95°E	26.67°N	73.64°E	UT-1
IFR1	Ifrane Seismic	33.52°N	-5.13°E	24.23°N	71.59°E	UT-1
OUCA	Ouca	31.206°N	-7.87°E	21.09°N	69.02°E	UT-1
TETN	Tetouan	35.56°N	-5.36°E	27.35°N	71.78°E	UT-1

The average daily data of VTEC for all PRNs for IFR1, MELI, OUCA and TETN for all the days between 1^st and 28^th June 2020 were obtained by averaging the VTEC values for all identical pseudo-random numbers (PRNs) within a 24 hour period

[33]

and used to plot VTEC against Universal Time (UT) for each day and station. The VTEC against UT plots for each day were analyzed.

3. Results

3.1. Movement of the June 2020 Godzilla SDS over the Sahara

The movement of the Godzilla SDS over the Sahara was tracked using the Copernicus Sentinel-5P satellite mission which was launched by the European Space Agency (ESA) on 13^th October 2017. This satellite tracked the movement of the Godzilla SDS from 1st June to 30th June 2020 across the Sahara desert using the Google Earth Engine (GEE), which is a cloud-based platform that stores a variety of satellite images used to detect changes in landscape

[34]

and the Sentinel-5P Aerosol Index (SAI), which qualitatively shows elevated aerosol layers in atmosphere

[35]

. Between 1^st and 3^rd June 2020, the Godzilla SDS was observed in Niger, Mali and Chad as in Figure 2(a), 2(b) and 2(c). Between 4th and 6th June 2020, the dust plume was seen to expand horizontally covering a wider range towards Mauritania as in Figure 2(d), 2(e) and 2(f). By 7th to 9th June 2020, the Godzilla SDS had extended to Western Sahara, Niger, Mauritania, Chad

[36, 37]

as in Figure 2(g), 2(h), and 3(a). Between 10th and 12th June 2020, the dust plume extended to eastern countries such as Libya and Sudan as in Figure 3(b), 3(c) and 3(d). Between 15th and 18th June 2020, the Western part of Africa such as Mauritania, Mali, Morocco and Western Sahara felt the greatest impact of the Godzilla SDS

[6]

as in Figure 3(g), 3(h), 4(a) and 4(b). By 20th June 2020, the first traces of dust had reached the Caribbean

[38]

as in Figure 4(d) and 4(e).

Download: Download full-size image

Figure 2. The Copernicus Sentinel-5P satellite images of Godzilla SDS over the Sahara for (a 01.06.2020 (b) 02.06.2020 (c) 03.06.2020 (d) 04.06.2020 (e) 05.06.2020 (f) 06.06.2020 (g) 07.06.2020 and (h) 07.06.2020 (Modified Copernicus Sentinel data, 2020, processed by ESA).

From 21^st June to 26^th June 2020, large SDS traces moved to the upper parts of the Sahara as in Figures 4(e), 4(f), 4(g), 4(h), 5(a) and 5(b). Between 28th and 30th June 2020, there was a decrease in the dust plume crossing over into the Atlantic Ocean.

In Figures 2, 3, 4 and 5, the cream colour on the SAI indicates absence of aerosol in the atmosphere while red colour shows presence of aerosols in high concentrations during the Godzilla sand and dust storm of June 2020 as tracked by the Copernicus Sentinel-5P satellite.

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Figure 3. The Copernicus Sentinel-5P satellite images of Godzilla SDS over the Sahara for (a) 09.06.2020 (b) 10.06.2020 (c) 11.06.2020 (d) 12.06.2020 (e) 13.06.2020 (f) 14.06.2020 (g) 15.06.2020 and (h) 16.06.2020 (Modified Copernicus Sentinel data, 2020, processed by ESA).

A close analysis of the Copernicus Sentinel-5P satellite images from 1^st June to 26^th June 2020 shows a noticeable change in the aerosol concentrations over the Sahara during the period. The greatest influence of the Godzilla SDS over Morocco was felt between 16^th and 26^thJune 2020 as depicted by Figures 3(h), 4(a), 4(b), 4(c), 4(d), 4(e), 4(f), 4(g), 5(a) and 5(b).

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Figure 4. The Copernicus Sentinel-5P satellite images of Godzilla SDS over the Sahara for (a) 17.06.2020 (b) 18.06.2020 (c) 19.06.2020 (d) 20.06.2020 (e) 21.06.2020 (f) 22.06.2020 (g) 23.06.2020 and (h) 24.06.202 (Modified Copernicus Sentinel data, 2020, processed by ESA).

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Figure 5. The Copernicus Sentinel-5P satellite images of Godzilla SDS over the Sahara for (a) 25.06.2020 and (b) 26.06.202 (Modified Copernicus Sentinel data, 2020, processed by ESA).

3.2. Variation of Solar Wind Parameters Between 1^stand 30^th June 2020

Figure 6 depicts the changes in IMF-Bz, IEF-Ey, V, K_p and Dst indices between 1^st and 30^th June 2020.

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Figure 6. Variations of Solar wind parameters: IMF-Bz, IEF-Ey and V speed and the geomagnetic indices: K_p and Dst index, between 1^st and 30^th June 2020.

From Figure 6 it is noted that the least value of the southward turning of the IMF-Bz was -6 nT with corresponding rise of IEF-Ey of 4 mV/m on 1^st June, 7^th June, 19^th June and 26^th June 2020. The solar wind speed rose to maximum of about 470 km/s on 7^th and 10^th June 2020. The highest kp index value of about 3.7 was attained on 7^th June 2020. The lowest Dst value of -25 nT was attained on 1^st June 2020. The solar wind parameters in Figure 6 show a minimum solar wind speed of 270 km/s on 16^th June 2020 and maximum solar wind of 360 km/s on 20^th June 2020. Generally, between 1^st and 30^th June 2020, IMF-Bz ranged between -6 and 5nT while IE-Ey ranged between -3 and 3 mV/m. The V ranged between 300 and 470km/s. The Kp index values ranged between 0 and 3.7 while the Dst index ranged between -30 and 20 nT. In summary, the values of the solar wind parameters and geomagnetic indices between 1^st and 30^th June 2020 in Figure 6 indicate that the geomagnetic field influence on the ionosphere was very minimal during the study period.

3.3. Variations of VTEC Against Universal Time (UT) During the Godzilla SDS of June 2020 over IFR1, MELI, OUCA and TETN

The ionospheric variability over IFR1, MELI, OUCA and TETN in Morocco was examined using VTEC against UT plots for the period between 1^st and 28^th June 2020.

3.3.1. Variations of VTEC Against UT Between 1^st and 4^th June over IFR1, MELI, OUCA and TETN

Figure 7(a), 7(b), 7(c) and 7(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 1^st, 2^nd, 3^rd and 4^th June 2020 respectively. There was a noticeable reduction in daily maximum VTEC values over all the four GNSS receiver stations between 1^st and 4^th June 2020. IFR1 had a daily maximum VTEC value of 14 TECU on 1^st June, which reduced to 13 TECU on 2^nd and 3^rd June 2020 and to 12 TECU on 4^th June 2020. MELI had a daily maximum VTEC value of 17 TECU on 1^st June, which reduced to 16 TECU on 2^nd June, 15 TECU on 3^rd June and 12 TECU on 4^th June 2020. OUCA had a daily maximum VTEC value of 19 TECU on 1^st June, which reduced to 17 TECU on 2^nd and 3^rd June and 14 TECU on 4^th June 2020. TETN had a daily maximum VTEC value of 17 TEC on 1^st and 2^nd June, which reduced to 14 TECU on 3^rd June and 13 TECU on 4^th June 2020. TEC depletions of depth between 3 – 4 TECU were also observed between 12:00 UT and 18:00 UT over IFR1 and OUCA on 2^nd June and over IFR1, MELI, OUCA and TETN on 4^th June 2020.

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Figure 7. Plot of VTEC against UT for the period (a) 01.06.2020 (b) 02.06.2020 (c) 03.06.2020 and (d) 04.06.2020 over IFR1, MELI, OUCA and TETN GNSS receiver stations.

3.3.2. Variations of VTEC Against UT Between 5^th and 8^th June 2020 over IFR1, MELI, OUCA and TETN

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Figure 8. Plot of VTEC against UT for period (a) 05.06.20200 (b) 06.06.2020 (c) 07.06.2020 and 08.06.2020 over IFR1, MELI, OUCA and TETN.

Figure 8(a), 8(b), 8(c) and 8(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 5^th, 6^th, 7^th and 8^th June 2020 respectively. Daily maximum VTEC values over all the four GNSS receiver stations were seen to rise between 5^th and 7^th June and drop on 8^th June 2020. IFR1 had a daily maximum VTEC value of 11 TECU on 5^th June, which rose to 13 TECU on 6^th, 15 TECU on 7^th June 2020 and dropped to 11 TECU on 8^th June 2020. MELI had a daily maximum VTEC value of 13 TECU on 5^th June, which increased to 15 TECU on 6^th June, 16 TECU on 7^th and reduced to 12 TECU on 8^th June 2020. OUCA had a daily maximum VTEC value of 15 TECU on 5^th June, which increased to 17 TECU on 6^th June, 19 TECU on 7^th June and dropped to 16 TECU on 8^th June 2020. TETN had a daily maximum VTEC value of 13 TECU on 5^th June, which increased to 16 TECU on 6^th June, 17 TECU on 7^th June and dropped to 12 TECU on 8^th June 2020. Multiple TEC depletions of depths between 3 – 4 TECU were also observed over IFR1, OUCA, MELI and TETN on 5^th, 6^th and 7^th June 2020.

3.3.3. Variations of VTEC Against UT Between 9^th and 12^th June 2020 over IFR1, MELI, OUCA and TETN

Figure 9(a), 9(b), 9(c) and 9(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 9^th, 10^th, 11^th and 12^thJune 2020 respectively. Daily maximum VTEC values over all the four GNSS receiver stations were seen to vary within a range of 13 to 16 TECU between 8^th and 12^th June 2020. IFR1 had a daily maximum VTEC value of 13 TECU on 9^th, 10^th and 12 June and 14 TECU on 11^th June 2020. MELI had a daily maximum VTEC value of 14 TECU on 9^th and 11^th June 2020 and 14 TECU on 10^th and 12^th June 2020. OUCA had a daily maximum VTEC value of 15 TECU on 9^th June, 16 TECU on 10^th June, 17 TECU on 11^th June and 18 TECU on 12^th June 2020. TETN had a daily maximum VTEC value of 13 TECU on 9^th June, 16 TECU on 10^th and 11^th June 2020 and 13 TECU on 12^th June 2020. TEC depletions of depths of 5 TECU were observed over TETN on 9^th, 10^th, 11^th and 12^th June 2020.

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Figure 9. Plot of VTEC against UT for period (a) 09.06.2020 (b) 10.06.2020 (c) 11.06.2020 and (d) 12.06.2020 over IFR1, MELI, OUCA and TETN.

3.3.4. Variations of VTEC Against UT Between 13^th and 16^th June 2020 over IFR1, MELI, OUCA and TETN

Figure 10(a), 10(b), 10(c) and 10(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 13^th, 14^th, 15^th and 16^thJune 2020 respectively. Daily maximum VTEC values over IFR1 were seen to vary within a range of 12 to 15 TECU between 13^th and 16^th June 2020. IFR1 had a daily maximum VTEC value varying between 10 and 15 TECU between 13^th and 16^th June 2020. MELI had a daily maximum VTEC value ranging between 10 TECU and 15 TECU between 13^th and 16^th June 2020. OUCA had a daily maximum VTEC value of between 13 TECU and 13 TECU between 13^th and 16^th June 2020. TETN had a daily maximum VTEC value of between 14 TECU and 16 TECU between 13^th and 16^th June 2020. TEC depletions of depths of 5 TECU were observed over TETN on 9^th, 10^th, 11^th and 12^th June 2020. It was however noted from Figure 10(a), 10(b) and 10(c) that the ionosphere over all the four GNSS stations was very disturbed between 12:00 UT and 20:00 UT on 13^th, 14^th, and 15^th. Figure 10(d) shows the ionosphere over all the four GNSS stations disturbed the whole day on 16^th June 2020.

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Figure 10. Plot of VTEC against UT for period (a) 13.06.2020 (b) 14.06.2020, (c) 15.06.2020 and (d) 16.06.2020 over IFR1, MELI, OUCA and TETN.

3.3.5. Variations of VTEC Against UT Between 17^th and 20^th June 2020 over IFR1, MELI, OUCA and TETN

Figure 11(a), 11(b), 11(c) and 11(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 17^th, 18^th, 19^th and 20^thJune 2020 respectively. Daily maximum VTEC values over the four GNSS stations appeared to fluctuate from day to day and station to station. IFR1 had a daily maximum VTEC value of 16 TECU on 17^th June, 15 TECU on 18^th June, 14 TECU on 19^th June and 15 TECU on 20^th June 2020. MELI had a daily maximum VTEC value of 16 TECU on 17^th and 18^th June, 15 TECU on 19^th June and 18 TECU on 20^th June 2020. OUCA had a daily maximum VTEC value of 18 TECU on 17^th June, 20 TECU on 18^th June, 16 TECU on 19^th and 20^th June 2020. MELI had a daily maximum VTEC value of 18 TECU on 17^th and 18^th June 2020, 16 TECU on 19^th June and 20^th June 2020. Multiple TEC depletions of depth between 3 to 6 TECU were also observed over IFR1, MELI, OUCA and MELI on 17^thto 20^th June 2020. The ionosphere over the four GNSS receiver stations also showed disturbances in all the days as indicated in Figures 11(a), 11(b), 11(c) and 11(d).

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Figure 11. Plot of VTEC against UT for period (a) 17.06.2020 (b) 18.06.2020 (c) 19.06.2020 and (d) 20.06.2020 over IFR1, MELI, OUCA and TETN.

3.3.6. Variations of VTEC Against UT Between 21^st and 24^th June 2020 over IFR1, MELI, OUCA and TETN

Figure 12(a), 12(b), 12(c) and 12(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 21^st, 22^nd, 23^rd and 24^th June 2020 respectively. Daily maximum VTEC values over the four GNSS receiver stations varied between 13 TECU and 16 TECU. IFR1 had a daily maximum VTEC value of 13 TECU on 21^st and 24^th June, 14 TECU on 22^nd June and 12 TECU on 23^rd June 2020. MELI had a daily maximum VTEC value of 13 TECU on 21^st and 23^rd June, 15 TECU on 22^nd June and 14 TECU on 24^th June 2020. OUCA had daily maximum VTEC values of 15 TECU on 21^st and 24^th June 2020, 16 TECU on 22^nd and 23^rd June 2020. MELI had a daily maximum VTEC value of 14 TECU on 21^st, 22^nd and 24^th June 2020 and 13 TECU on 23^rd June 22020. TEC depletions of depths 2 to 3 TECU were also observed. The ionosphere was also observed to be disturbed indicated by Figure 12(a), 12(b), 12(c) and 12(d).

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Figure 12. Plot of VTEC against UT for period (a) 21.06.2020 (b) 22.06.2020 (c) 23.06.2020 and (d) 24.06.2020 over IFR1, MELI, OUCA and TETN.

3.3.7. Variations of VTEC Against UT Between 25^th and 28^th June 2020 over IFR1, MELI, OUCA and TETN

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Figure 13. Plot of VTEC against UT for period (a) 25.06.2020 (b) 26.06.2020 (c) 27.06.2020 and (d) 28.06.2020 over IFR1, MELI, OUCA and TETN.

Figure 13(a), 13(b), 13(c) and 13(d) shows VTEC against UT plots over IFR1, MELI, OUCA and TETN on 25^th, 26^th, 27^th and 28^th June 2020 respectively. Large TEC depletions of depths 5 to 6 TECU were observed over the four GNSS receiver stations on 24^th June 2020. However, smaller TEC depletions of depth 2- 3 TECU were also observed over IFR1 on 26^th and 28^th June and OUCA on 27^th June 2020.

4. Discussions

4.1. Daily Ionospheric TEC Variability over IFR1, MELI, OUCA and TETN During the Godzilla SDS Event of June 2020

We have investigated the possible relation between ionospheric TEC perturbations and the Godzilla SDS event of June 2020 over Morocco. In Figures 2, 3, 4 and 5, the aerosol concentrations levels over OUCA, IFR1, TETN and MELI resulting from the Godzilla SDS kept varying between 1^st June and 28^th June 2020. Between 1^st and 4^th June there were very low aerosol concentrations over the four GNSS receiver stations. Between 5^th and 13^thJune, the aerosol concentrations over OUCA were seen to increase steadily but MELI, IFR1 and TETN still experienced low aerosol concentrations. From 14^th to 18^th June 2020, OUCA experienced increased aerosol concentrations. On 19^th June 2020, MELI and OUCA experienced high aerosol concentrations. Between 20^th and 22^nd June 2020, OUCA continued to experience higher aerosol concentration levels. Between 23^rd and 26^th June 2020, all the four GNSS receiver stations experienced increased aerosol concentrations. These changes in the aerosol levels over the four GNSS receiver stations could directly be linked to the variability of VTEC against UT between 1^st and 28^th June as indicated by Figures 7, 8, 9, 10, 11, 12 and 13. It is noted that between 1^st and 11^th June 2020, there were very minimal ionospheric TEC perturbations as depicted by the VTEC plots in Figures 7, 8 and 9. Between 12^th and 18^th June 2020, visible ionospheric TEC perturbations were noted over all the GNSS receiver stations and corresponded to increased aerosol concentrations in the atmosphere. Between 19^th and 26^th June 2020, there were increased ionospheric TEC perturbations over all the four GNSS receiver stations. It should be noted that all the four GNSS receiver stations exhibited these ionospheric TEC disturbances. This is because during SDS events, sand and dust particles are blown up above the ground and once they are suspended, they are advected thousands of kilometers from their point of origin and hence the generated electric fields propagate horizontally over considerable distances ending up affecting electron density thousands of kilometers away

[39]

. Since June 2020 is a geomagnetically quiet period as depicted by the solar wind parameters and geomagnetic indices in Figure 6

[40]

, the observed variability of the ionosphere above the four GNSS receiver stations in Morocco can only be attributed to two possible ionization sources. One of the sources is the presence of the Extreme Ultra Violet (EUV) radiation from the Sun, which varies over a 24 hour period between daytime and nighttime and over a 11 year period within solar cycle. The diurnal variation of VTEC with time over IFR1, MELI, OUCA and TETN for most days shows characteristics typical to low latitude ionosphere where VTEC is low during pre-dawn, then increases gradually reaching maximum in the afternoon and then gradually decreasing after sunset

[41, 42]

. The other possible source of ionospheric TEC variability during the SDS event is the atmospheric electrification resulting from the fast moving sand and dust particles in the atmosphere. Atmospheric transport, suspension and interaction of individual sand and dust particles rapidly bring up a substantial amount of electrification

[11]

. Extensive flow-based modeling has shown that rotating dust systems (dust devils) can produce very large electric fields in excess of 10kV/m within few seconds

[11, 43, 44]

. The dust electrification process during sand and dust storm events is due to contact and triboelectric charging between blowing sand and dust particles. Duf, N. f & Lacks, D. J. suggested that during collisions, the smaller sand and dust particles acquire negative charge with respect to larger particles. The larger particles usually stay close to the surface while charged smaller particles are brought into suspension and transported into the atmosphere by local turbulence. This gravitational charge separation is always consistent with increase in atmospheric electric fields

[45]

. The charge separation maintains current flow between the lower atmosphere and the ionosphere through a Global Electric Circuit (GEC) model

[11]

. The ionosphere responds to the generated atmospheric electric field by modifying the ionospheric conductivity. Electrical conductivity which is the ratio between current density (i in A/m) and electric field (E in V/m) is given by equation 6

[15]

Electrical conductivity,

(6)

Where v is the velocity of the relevant particles, N is their concentration and e is the charge on each.

The horizontal layering of the ionosphere has the greatest effect on vertical currents. This affects the rate at which ions and electrons recombine, hence producing both positive phases (exhibited as increases in electron concentration) and negative phases (exhibited as decreases in electron concentration) in the ionosphere

[15, 46]

as observed in the VTEC plots in Figures 7, 8, 9, 10, 11, 12 and 13.

By tracking the movement of the Godzilla SDS as indicated in Figures 2, 3, 4 and 5, it was noted that the intensity of the storm over Morocco was higher between 16^th and 26^th June 2020. The dust plume was therefore considered to have been so much electrically active during this period. This corresponded with increased ionospheric TEC disturbances recorded on 16^th, 17^th, 18^th, 20^th, 21^st, 22^nd, 23^rd, 24^th and 25^th June 2020. These results conform with results from earlier studies done by

[14, 20]

on possible relations between sand and dust storm and ionospheric TEC perturbations.

4.2. Variations of Daily Maximum VTEC Values During the Godzilla SDS of June 2020 over IFR1, MELI, TETN and OUCA

The variations of daily maximum VTEC values for each day from 1^st to 28^th June 2020 and for each station were plotted in a scatter plot as in Figure 14. Across all the four GNSS receiver stations, continuous increases and decreases of daily maximum VTEC values were observed from 1^st to 28^th June 2020. Since this behavior is occurring during days having low aerosol concentrations and those having high aerosol concentrations in the atmosphere, this might not be directly linked to the effect of the Godzilla SDS event. However, we might link it to the extra Earth warming which degenerated into extreme convectional currents, which was a precursor for the Godzilla SDS

[6]

and was propagated further during the SDS event due to change in atmospheric composition brought about by the change in global circulation pattern of the charge structures. The global circulation pattern majorly depends on the variation in particle charge with particle size and the effect of gravitational charge separation

[11]

. The VTEC plots for each day over all the for receiver stations exhibited similar trends. This shows that they exhibited almost similar ionospheric dynamics.

Download: Download full-size image

Figure 14. Scatter plots showing variability of daily maximum VTEC values over (a) IFR1, (b) MELI, (c) OUCA and (d) TETN between 1^st and 28^th June 2020.

4.3. VTEC Depletions and Nighttime VTEC Enhancements During the Godzilla SDS of June 2020 over IFR1, MELI, OUCA and TETN

In this study, VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12^th, 14^th, 17^th, 20^th and 25^th June 2020. Successive TEC depletions were also noted over the four GNSS receiver stations on 16^th and 23^rdJune 2020. However, some days had VTEC depletions and enhancements occurring at around 20:00 UT. These enhancements occurred after the Pre-reversal enhancement (PRE) and thus regarded as nighttime VTEC enhancements. Their occurrences were summarized in Table 2 as shown.

Table 2. Nighttime peak of VTEC for IFR1, MELI, OUCA and TETN between 1^st and 28^th June 2020.

DATE	GNSS Receiver Station	Occurrence Time
9^th June 2020	IFR1, OUCA, MELI, TETN	20:00 UT
13^th June 2020	IFR1, OUCA, MELI, TETN	21:00 UT
15^th June 2020	IFR1, OUCA, MELI, TETN	20:00 UT
17^th June 2020	IFR1, OUCA, MELI, TETN	20:00 UT
19^th June 2020	IFR1, OUCA, MELI, TETN	20:00 UT
20^th June 2020	IFR1, OUCA, MELI, TETN	20:00 UT
21^stJune 2020	IFR1, OUCA, MELI, TETN	20:00 UT

In Table 2, it is clearly noted that nighttime VTEC enhancements majorly occurred between 20:00 and 21:00 UT on 9^th, 13^th, 15^th, 17^th, 19^th, 20^th and 21^st June 2020 over all the four GNSS receiver stations. It is also noted that this is the period when the intensity of the Godzilla SDS began increasing over Morocco and hence there seemed to be a relationship between the SDS event and the occurrence of nighttime VTEC enhancements. Although previous studies on VTEC have observed increases in nighttime VTEC enhancements, there is still no agreement on their origin

[47]

. However, some studies suggest that the nighttime VTEC enhancements might be associated with the westward directed electric field

[47, 48]

. In fair weather environment, the ionosphere and protonosphere are strongly coupled through the charge exchange reactions between protons and atomic oxygen ions. That is, as the F-region builds up after sunrise, plasma moves up to higher latitudes where protons are created and flow up along the field lines to populate the protonosphere. Proton population flows back to the lower levels in the evening, where it charge-exchanges back to oxygen ions, thus helping maintain the F-regions at night

[15]

. Modeling studies by Jackson, T. L. et al (a); Kok, J. F. & Renno, N. O. and Jackson, T. L. et al, (b) have shown that in the sand and dust environment, the electron avalanche processes which include dust and electron absorption or losses and the active conversion to electron dissociative attachment could develop after sunset leading to electron excitation and new chemical products

[49-51]

. Polarization charges arising from the conductivity gradients at the terminator enhances eastward electric field after sunset for more than an hour

[52]

. Farrel, W. M. et al noted that the electron avalanche represents a substantial modification of the atmospheric conductivity

[53]

. This modification might also be the cause of the occurrence of nighttime VTEC enhancements since the penetration of electrons and ions from the upper atmosphere into the ionosphere contributes to extraordinary production of electrons and ions in the ionosphere.

Although the study has revealed day to day ionospheric TEC variability during the Godzilla SDS event, questions about the physical mechanism responsible for some observed variability remains unanswered. For example, it still remains unclear how much of the observed variability is due to inherent variations in the atmosphere-ionosphere interactions and how much can be attributed to mesospheric processes.

5. Conclusion

In this paper, we have considered an interesting SDS event and used TEC measurement to bring out possible ionospheric TEC variability resulting from atmospheric-ionospheric interaction during the SDS storm event. Our results have shown increased electron density perturbations over the four GNSS receiver stations between 16^th and 28^th June 2020. The daily maximum VTEC values over the four GNSS receiver stations also showed an interesting trend of significant enhancement and decrease in the whole study period. The VTEC plots for each day over all the four GNSS receiver stations exhibited similar trends, hence exhibited similar ionospheric dynamics. VTEC depletion of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12^th, 14^th, 17^th, 20^th and 25^th June 2020. Nighttime VTEC enhancements were also noted to majorly occur between 20:00 and 21:00 UT on 9^th, 13^th, 15^th, 17^th, 19^th, 20^th and 21^st June 2020. This might be attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. Electron avalanche has been known to represent a substantial modification of the atmospheric conductivity. Thus, energetic particles like electrons and ions from the upper atmosphere can penetrate the ionosphere and contribute to extraordinary production of electrons and ions in the ionosphere influencing electron density.

Abbreviations

ESA	European Space Agency
GEC	Global Electric Circuit
GEE	Google Earth Engine
GIM	Global Ionospheric Maps
GNSS	Global Navigation Satellite System
GPS	Global Positioning System
IEF	Interplanetary Electric Field
IMF	Interplanetary Magnetic Field
Kv	Kilo-Volt
Kv/m	Kilo-Volt Per Metre
MHz	Mega-Hertz
NOAA	National Oceanic and Atmospheric Administration
PPP	Precise Point Positioning
RINEX	Receiver Independent Exchange
RST	Robust Satellite Technology
SAI	Sentinel-5P Aerosol Index
SEVIRI	Spinning Enhanced Visible & Infrared Imager
SDS	Sand and Dust Storm
STEC	Slant Total Electron Content
TEC	Total Electron Content
TECU	Total Electron Content Unit
UT	Universal Time
USA	United States of America

Acknowledgments

The authors thank the University of NAVSTAR Consortium: http://unavco.org/data/gps-gnssdata/ for the GNSS data; Kyoto: wdc.kugi.kyoto.u.ac.jp/dst/index.html and Kyoto: www.kugi.kyoto-ua.ac.jp/kp for the geomagnetic activity data; https://omniweb.gsfc.nasa.gov/form/dx1.html for the daily values of solar wind parameters and the European Space Agency for the Copernicus Sentinel-5P satellite images of June 2020 Godzilla SDS over the Sahara. They also thank Prof Gopi Seemala of the Indian Institute of Geomagnetism for the GPS-TEC analysis software.

Author Contributions

Uluma Edward: Conceptualization, Data curation, methodology, data analysis, software, resources, writing and editing original document and revision of the final manuscript.

Chali Idosa Uga: Conceptualization, Data curation, methodology, data analysis, software, writing and editing original document and revision of the final manuscript.

Athwart Davis Odhiambo: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Binod Adhikari: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Sujan Prasad Gautam: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Ndinya Boniface: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Omondi George: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Ashutosh Giri: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Dessalegn Teferi: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Negasa Belay: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Ashok Silwal: Reviewing and Editing the original draft, software, methodology, data analysis and revision of the final manuscript.

Funding

This work did not receive any funding.

Data Availability Statement

Data can be made available on request.

Conflicts of Interest

The authors declare no conflicts of interest.

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Edward, U., Uga, C. I., Odhiambo, A. D., Adhikari, B., Gautam, S. P., et al. (2024). Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. International Journal of Astrophysics and Space Science, 12(1), 1-16. https://doi.org/10.11648/j.ijass.20241201.11

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Edward, U.; Uga, C. I.; Odhiambo, A. D.; Adhikari, B.; Gautam, S. P., et al. Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. Int. J. Astrophys. Space Sci. 2024, 12(1), 1-16. doi: 10.11648/j.ijass.20241201.11

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Edward U, Uga CI, Odhiambo AD, Adhikari B, Gautam SP, et al. Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. Int J Astrophys Space Sci. 2024;12(1):1-16. doi: 10.11648/j.ijass.20241201.11

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@article{10.11648/j.ijass.20241201.11,
  author = {Uluma Edward and Chali Idosa Uga and Athwart Davis Odhiambo and Binod Adhikari and Sujan Prasad Gautam and Ndinya Boniface and Omondi George and Ashutosh Giri and Dessalegn Teferi and Negasa Belay and Ashok Silwal},
  title = {Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020
},
  journal = {International Journal of Astrophysics and Space Science},
  volume = {12},
  number = {1},
  pages = {1-16},
  doi = {10.11648/j.ijass.20241201.11},
  url = {https://doi.org/10.11648/j.ijass.20241201.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijass.20241201.11},
  abstract = {During sand and dust storm (SDS) events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere which plays a very important role in the atmosphere-ionosphere coupling. The Godzilla SDS began on 5th June 2020 in Algeria following a decrease in pressure and spread to other areas across the Sahara between 6th and 28th June 2020. Using SDS data from Copernicus Sentinel-5P satellite mission and Vertical Total Electron Content (VTEC) data from four GNSS receiver stations: IFR1 (Ifrane Seismic), MELI (Melilla), TETN (Tetouan) and OUCA (Ouca) over Morocco, we investigate the possible ionospheric TEC variability over the four GNSS receiver stations during the Godzilla SDS event which was tracked using the Sentinel-5P Satellite mission. Solar wind parameters: Horizontal component of Interplanetary Magnetic Field (IMF-Bz), interplanetary Electric Field (IEF-Ey) and solar wind speed (V) and geomagnetic indices: Disturbance Storm Time (Dst) and Planetary K (Kp) indices were examined and showed very minimal geomagnetic influence during the period. We observed major ionospheric disturbances over the four Global Navigation Satellite System (GNSS) receiver stations on 16th, 17th, 18th, 21st, 22nd, 23rd 25th and 26th June 2020: the period with the Sentinel-5P Aerosol Index (SAI) of more than 4 as recorded by the Sentinel-5P Satellite engine. The daily VTEC values over the four GNSS receiver stations recorded continuous electron density perturbations during these days. Apart from the ionospheric TEC perturbations, significant enhancements and decreases in daily maximum VTEC values over the four GNSS receiver stations were also noted. These were attributed to the changes in the atmospheric electric fields generated by the SDS event. The VTEC plots for each day exhibited similar trends, hence exhibited the same ionospheric dynamics. VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12th, 14th, 17th, 20th and 25th June 2020. Nighttime VTEC enhancements were also noted and majorly occurred between 20:00 and 21:00 UT on 9th, 13th, 15th, 17th, 19th, 20th and 21st June 2020. This was attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. In conclusion, the Godzilla SDS of June 2020 led to the electron density perturbations over Morocco.
},
 year = {2024}
}

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TY  - JOUR
T1  - Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020

AU  - Uluma Edward
AU  - Chali Idosa Uga
AU  - Athwart Davis Odhiambo
AU  - Binod Adhikari
AU  - Sujan Prasad Gautam
AU  - Ndinya Boniface
AU  - Omondi George
AU  - Ashutosh Giri
AU  - Dessalegn Teferi
AU  - Negasa Belay
AU  - Ashok Silwal
Y1  - 2024/07/15
PY  - 2024
N1  - https://doi.org/10.11648/j.ijass.20241201.11
DO  - 10.11648/j.ijass.20241201.11
T2  - International Journal of Astrophysics and Space Science
JF  - International Journal of Astrophysics and Space Science
JO  - International Journal of Astrophysics and Space Science
SP  - 1
EP  - 16
PB  - Science Publishing Group
SN  - 2376-7022
UR  - https://doi.org/10.11648/j.ijass.20241201.11
AB  - During sand and dust storm (SDS) events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere which plays a very important role in the atmosphere-ionosphere coupling. The Godzilla SDS began on 5th June 2020 in Algeria following a decrease in pressure and spread to other areas across the Sahara between 6th and 28th June 2020. Using SDS data from Copernicus Sentinel-5P satellite mission and Vertical Total Electron Content (VTEC) data from four GNSS receiver stations: IFR1 (Ifrane Seismic), MELI (Melilla), TETN (Tetouan) and OUCA (Ouca) over Morocco, we investigate the possible ionospheric TEC variability over the four GNSS receiver stations during the Godzilla SDS event which was tracked using the Sentinel-5P Satellite mission. Solar wind parameters: Horizontal component of Interplanetary Magnetic Field (IMF-Bz), interplanetary Electric Field (IEF-Ey) and solar wind speed (V) and geomagnetic indices: Disturbance Storm Time (Dst) and Planetary K (Kp) indices were examined and showed very minimal geomagnetic influence during the period. We observed major ionospheric disturbances over the four Global Navigation Satellite System (GNSS) receiver stations on 16th, 17th, 18th, 21st, 22nd, 23rd 25th and 26th June 2020: the period with the Sentinel-5P Aerosol Index (SAI) of more than 4 as recorded by the Sentinel-5P Satellite engine. The daily VTEC values over the four GNSS receiver stations recorded continuous electron density perturbations during these days. Apart from the ionospheric TEC perturbations, significant enhancements and decreases in daily maximum VTEC values over the four GNSS receiver stations were also noted. These were attributed to the changes in the atmospheric electric fields generated by the SDS event. The VTEC plots for each day exhibited similar trends, hence exhibited the same ionospheric dynamics. VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12th, 14th, 17th, 20th and 25th June 2020. Nighttime VTEC enhancements were also noted and majorly occurred between 20:00 and 21:00 UT on 9th, 13th, 15th, 17th, 19th, 20th and 21st June 2020. This was attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. In conclusion, the Godzilla SDS of June 2020 led to the electron density perturbations over Morocco.

VL  - 12
IS  - 1
ER  -

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Author Information

Uluma Edward

Department of Physics, Masinde Muliro University of Science & Technology, Kakamega, Kenya

Contact Email

http://orcid.org/0000-0003-4115-8042
Chali Idosa Uga

Department of Physics, Jimma University, Jimma, Oromia, Ethiopia; Department of Space Science, University of Alabama in Huntsville, Alabama, USA

http://orcid.org/0000-0002-4699-8342
Athwart Davis Odhiambo

Department of Physics, Masinde Muliro University of Science & Technology, Kakamega, Kenya

http://orcid.org/0000-0003-2855-3670
Binod Adhikari

Department of Physics, St. Xaviers’s College, Kathmandu, Nepal

http://orcid.org/0000-0002-2799-9112
Sujan Prasad Gautam

Department of Space Science, University of Alabama in Huntsville, Alabama, USA

http://orcid.org/0000-0001-7379-4268
Ndinya Boniface

Department of Physics, Masinde Muliro University of Science & Technology, Kakamega, Kenya

http://orcid.org/0000-0003-1970-7842
Omondi George

Department of Physics and Materials Science, Maseno University, Maseno, Kenya

http://orcid.org/0000-0002-5187-7895
Ashutosh Giri

Department of Physics, St. Xaviers’s College, Kathmandu, Nepal

http://orcid.org/0000-0001-8501-0950
Dessalegn Teferi

Department of Physics, Jimma University, Jimma, Oromia, Ethiopia

http://orcid.org/0000-0002-1413-4881
Negasa Belay

Department of Physics, Jimma University, Jimma, Oromia, Ethiopia

http://orcid.org/0000-0002-9232-3514
Ashok Silwal

Department of Space Science, University of Alabama in Huntsville, Alabama, USA

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APA Style

Edward, U., Uga, C. I., Odhiambo, A. D., Adhikari, B., Gautam, S. P., et al. (2024). Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. International Journal of Astrophysics and Space Science, 12(1), 1-16. https://doi.org/10.11648/j.ijass.20241201.11

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ACS Style

Edward, U.; Uga, C. I.; Odhiambo, A. D.; Adhikari, B.; Gautam, S. P., et al. Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. Int. J. Astrophys. Space Sci. 2024, 12(1), 1-16. doi: 10.11648/j.ijass.20241201.11

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AMA Style

Edward U, Uga CI, Odhiambo AD, Adhikari B, Gautam SP, et al. Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020. Int J Astrophys Space Sci. 2024;12(1):1-16. doi: 10.11648/j.ijass.20241201.11

Copy | Download

@article{10.11648/j.ijass.20241201.11,
  author = {Uluma Edward and Chali Idosa Uga and Athwart Davis Odhiambo and Binod Adhikari and Sujan Prasad Gautam and Ndinya Boniface and Omondi George and Ashutosh Giri and Dessalegn Teferi and Negasa Belay and Ashok Silwal},
  title = {Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020
},
  journal = {International Journal of Astrophysics and Space Science},
  volume = {12},
  number = {1},
  pages = {1-16},
  doi = {10.11648/j.ijass.20241201.11},
  url = {https://doi.org/10.11648/j.ijass.20241201.11},
  eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijass.20241201.11},
  abstract = {During sand and dust storm (SDS) events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere which plays a very important role in the atmosphere-ionosphere coupling. The Godzilla SDS began on 5th June 2020 in Algeria following a decrease in pressure and spread to other areas across the Sahara between 6th and 28th June 2020. Using SDS data from Copernicus Sentinel-5P satellite mission and Vertical Total Electron Content (VTEC) data from four GNSS receiver stations: IFR1 (Ifrane Seismic), MELI (Melilla), TETN (Tetouan) and OUCA (Ouca) over Morocco, we investigate the possible ionospheric TEC variability over the four GNSS receiver stations during the Godzilla SDS event which was tracked using the Sentinel-5P Satellite mission. Solar wind parameters: Horizontal component of Interplanetary Magnetic Field (IMF-Bz), interplanetary Electric Field (IEF-Ey) and solar wind speed (V) and geomagnetic indices: Disturbance Storm Time (Dst) and Planetary K (Kp) indices were examined and showed very minimal geomagnetic influence during the period. We observed major ionospheric disturbances over the four Global Navigation Satellite System (GNSS) receiver stations on 16th, 17th, 18th, 21st, 22nd, 23rd 25th and 26th June 2020: the period with the Sentinel-5P Aerosol Index (SAI) of more than 4 as recorded by the Sentinel-5P Satellite engine. The daily VTEC values over the four GNSS receiver stations recorded continuous electron density perturbations during these days. Apart from the ionospheric TEC perturbations, significant enhancements and decreases in daily maximum VTEC values over the four GNSS receiver stations were also noted. These were attributed to the changes in the atmospheric electric fields generated by the SDS event. The VTEC plots for each day exhibited similar trends, hence exhibited the same ionospheric dynamics. VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12th, 14th, 17th, 20th and 25th June 2020. Nighttime VTEC enhancements were also noted and majorly occurred between 20:00 and 21:00 UT on 9th, 13th, 15th, 17th, 19th, 20th and 21st June 2020. This was attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. In conclusion, the Godzilla SDS of June 2020 led to the electron density perturbations over Morocco.
},
 year = {2024}
}

Copy | Download

TY  - JOUR
T1  - Variability of Ionospheric Total Electron Content Over Morocco During the Godzilla Sand and Dust Storm of June 2020

AU  - Uluma Edward
AU  - Chali Idosa Uga
AU  - Athwart Davis Odhiambo
AU  - Binod Adhikari
AU  - Sujan Prasad Gautam
AU  - Ndinya Boniface
AU  - Omondi George
AU  - Ashutosh Giri
AU  - Dessalegn Teferi
AU  - Negasa Belay
AU  - Ashok Silwal
Y1  - 2024/07/15
PY  - 2024
N1  - https://doi.org/10.11648/j.ijass.20241201.11
DO  - 10.11648/j.ijass.20241201.11
T2  - International Journal of Astrophysics and Space Science
JF  - International Journal of Astrophysics and Space Science
JO  - International Journal of Astrophysics and Space Science
SP  - 1
EP  - 16
PB  - Science Publishing Group
SN  - 2376-7022
UR  - https://doi.org/10.11648/j.ijass.20241201.11
AB  - During sand and dust storm (SDS) events, atmospheric suspension and transport of sand and dust brings a reasonable amount of electrification in the atmosphere which plays a very important role in the atmosphere-ionosphere coupling. The Godzilla SDS began on 5th June 2020 in Algeria following a decrease in pressure and spread to other areas across the Sahara between 6th and 28th June 2020. Using SDS data from Copernicus Sentinel-5P satellite mission and Vertical Total Electron Content (VTEC) data from four GNSS receiver stations: IFR1 (Ifrane Seismic), MELI (Melilla), TETN (Tetouan) and OUCA (Ouca) over Morocco, we investigate the possible ionospheric TEC variability over the four GNSS receiver stations during the Godzilla SDS event which was tracked using the Sentinel-5P Satellite mission. Solar wind parameters: Horizontal component of Interplanetary Magnetic Field (IMF-Bz), interplanetary Electric Field (IEF-Ey) and solar wind speed (V) and geomagnetic indices: Disturbance Storm Time (Dst) and Planetary K (Kp) indices were examined and showed very minimal geomagnetic influence during the period. We observed major ionospheric disturbances over the four Global Navigation Satellite System (GNSS) receiver stations on 16th, 17th, 18th, 21st, 22nd, 23rd 25th and 26th June 2020: the period with the Sentinel-5P Aerosol Index (SAI) of more than 4 as recorded by the Sentinel-5P Satellite engine. The daily VTEC values over the four GNSS receiver stations recorded continuous electron density perturbations during these days. Apart from the ionospheric TEC perturbations, significant enhancements and decreases in daily maximum VTEC values over the four GNSS receiver stations were also noted. These were attributed to the changes in the atmospheric electric fields generated by the SDS event. The VTEC plots for each day exhibited similar trends, hence exhibited the same ionospheric dynamics. VTEC depletions of depths 3 to 6 TECU over all the four GNSS receiver stations were noted on 12th, 14th, 17th, 20th and 25th June 2020. Nighttime VTEC enhancements were also noted and majorly occurred between 20:00 and 21:00 UT on 9th, 13th, 15th, 17th, 19th, 20th and 21st June 2020. This was attributed to the development of the electron avalanche processes including dust and electron absorption or losses and the active conversion to electron dissociative attachment leading to electron excitation. In conclusion, the Godzilla SDS of June 2020 led to the electron density perturbations over Morocco.

VL  - 12
IS  - 1
ER  -

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