The Mexican Space Weather Service (SCiESMEX in Spanish) and
National Space Weather Laboratory (LANCE in Spanish) were organized in 2014
and in 2016, respectively,
to provide
space weather monitoring and alerts, as well as scientific research in
Mexico. In this work, we present the results of the first joint observations
of two events (22 June and 29 September 2015) with our local network of
instruments and their related products. This network includes the MEXART
radio telescope (solar flare and radio burst), the Compact Astronomical
Low-frequency, Low-cost Instrument for Spectroscopy in Transportable
Observatories (CALLISTO) at the MEXART station (solar radio burst), the Mexico
City Cosmic Ray Observatory (cosmic ray fluxes), GPS receiver networks
(ionospheric disturbances), and the Teoloyucan Geomagnetic Observatory (geomagnetic field). The observations show that we detected significant space
weather effects over the Mexican territory: geomagnetic and ionospheric
disturbances (22 June 2015), variations in cosmic ray fluxes, and also radio
communications' interferences (29 September 2015). The effects of these
perturbations were registered, for the first time, using space weather
products by SCiESMEX: total electron content (TEC) maps, regional geomagnetic index
Space weather (SW) phenomena influence the performance and
reliability of different modern technological systems; see for instance
There are some studies of particular SW events that affected the geomagnetic
field and ionosphere in Mexico, for example
The southern half of Mexican territory is located between the northern tropic
and the Equator. The Sun's incident ray path, at maximum elevation, remains
throughout the year between 35 and 81
Since 2014, Mexico has begun a strategy for SW awareness. In 2014, the
Mexican Space Weather Service (SCiESMEX) was created;
in 2016, the National Space Weather Laboratory (LANCE) and the
Repository of Space Weather Data (RICE) were established
The aim of this work is to estimate the impact of SW phenomena over Mexico.
We based our results on multilateral observations performed by the SCiESMEX
instrumental network. In this work, we addressed two events registered over
Mexico by SCiESMEX in 2015: on 22 June, and on 25–29 September. The first
event was mainly related to a M6.5 solar flare and a geomagnetic storm
that caused ionospheric perturbations. The second event was related to a
solar radio burst. The paper is organized as follows:
Sect.
This section describes the ground-based facilities for SW observations in Mexico.
The Mexican Array Radio Telescope (MEXART) is a transit instrument dedicated to
interplanetary scintillation (IPS) observations from compact radio sources
The telescope allows us to remotely infer some characteristics of solar wind streams crossing along the line of sight of the extragalactic radio sources detected by the instrument. This includes the tracking of large-scale interplanetary perturbations. The solar wind speeds and interplanetary density fluctuations along the lines of sights are computed with the use of the methods developed by SCiESMEX. When the line of sight of a radio source passes across the solar wind electronic density inhomogeneities, the radio signals are scattered, and a diffraction pattern is produced.
To infer some solar wind characteristics (velocity and density fluctuations)
from the IPS data, we apply a power spectra analysis to record the transit of
the radio source. We employ a theoretical model to obtain a power spectrum of
the IPS fluctuations. This IPS theoretical spectrum incorporates different
physical parameters, including solar wind speed. We fit the theoretical model
to the observed power spectra, obtaining the solar wind speed that best
matches the observation. The solar wind speed location is assumed at the
nearest point of the Sun to the line of sight. The solar wind density
fluctuations are estimated from the area under the curve of the observed IPS
spectrum; this area is equivalent to the scintillation index Reports can be found on the official web page of SCiESMEX
(
Solar radio bursts are spontaneous emissions of electromagnetic waves at low
frequencies in the outer solar atmosphere produced by shock waves close to
the corona or in the interplanetary medium
In 2015, a CALLISTO (Compact Astronomical Low-frequency, Low-cost Instrument for Spectroscopy in Transportable
Observatories) station was installed in the facilities of the MEXART
radio telescope (CALLISTO-MEXART station). This station forms part of the
e-CALLISTO network. Up to now, about 100 solar radio events have been
detected, and their radio noise spectrum at the site has been categorized
The product related to CALLISTO is the dynamic radio spectrograph; see
the example in Sect.
The Mexico City Cosmic Ray Observatory is equipped with two instruments: a
muon telescope and a neutron monitor (NM). The muon telescope detects the
hard component (negative and positive muons) produced by the decay of charged
pions, which are produced by interactions of the primary cosmic rays with the
atmospheric nucleus. It is composed of eight plates of a plastic scintillator;
four plates are located above the NM and four under it. The muons crossing
through the scintillators lose energy by ionization and produce fluorescent
radiation that travels to a photomultiplier
The cosmic ray observatory can detect flux variations caused by solar
activity, for example, when a coronal mass ejection (CME) strikes the Earth
and produces a sudden reduction in galactic cosmic ray flux intensity. This
kind of event is known as a Forbush decrease (FD)
The Teoloyucan Geomagnetic Observatory (TEO) is located near Mexico City
(at latitude 19.746
Since 2017, SCiESMEX, in collaboration with the Magnetic Service, has
estimated the local geomagnetic field changes with the
The quiet baseline is calculated by statistically removing the systematic
diurnal and monthly variations of
There are different GPS receiver networks operating in Mexico
The near-real-time TEC maps over Mexico are one of the products developed by
SCiESMEX. The results of TEC estimation by different methods and the
ionospheric
In 2015, the National Council of Science and Technology created a network of repositories for science and technology in Mexico. SCiESMEX manages the repository of the SW data. RICE provides the capabilities for massive and high-speed storage and processing of data from the networks of local and international SW instruments. The data in RICE can be processed in quasi-real time. The results are published on the official SCiESMEX web page both in weekly SW reports and as quasi-real-time SW values. This allows us to perform the continuous quasi-real-time monitoring of SW conditions and to analyze previous events.
Two solar transits detected by MEXART at 139.65 MHz. Electromagnetic flux measurements on 22 June 2015, during the occurrence of a solar flare (blue curve) and regular quiet solar transit (green curve).
On 19 June 2015 at 05:00 UTC, a filament eruption was detected in the
solar southeast quadrant of the solar disk. On 21 June 2015, between 01:00 and 03:00 UTC,
two solar flares erupted from the active region 2371 (M2 and M2.6), and a
halo CME, associated with these flares, was also detected. On the same day,
at 09:44 and 18:20 UTC, two other flares were released from the solar
atmosphere, with M3 and M1 categories, respectively
Scaled X-ray flux from the solar flare on 22 June 2015 by GOES satellite data (green curve) and a radio flux as detected by MEXART (blue curve) at 139.65 MHz.
On 22 June 2015, two CME arrivals were detected by the ACE spacecraft at
04:51 UTC (associated with the first filament eruption) and 17:59 UTC
(associated with the double-peaked M2 flare from the active region 2371 on
21 June). Shortly afterward, in the same active region, an M6 X-ray solar
flare with a full halo CME was detected at 17:59 UTC. This last CME arrived
at Earth 2 days later on 24 June at 12:58 UTC
Variations of parameters during 20–25 June 2015: H component of the
magnetic field by a local magnetometer in Mexico
The Sun, as the strongest radio source in the sky, is detected daily by the
MEXART. These solar transit radio observations allow us to statistically
characterize the flux and width of the Sun at 139.65 MHz and its variations
within the solar cycle. It is possible to record solar activity or a flare
during the recording of the solar transit, as occurred on 22 June 2015. During
the M6.5-class flare, the Sun was near the local zenith around 22
Forbush decrease detected by the Mexico City Cosmic Ray Observatory, generated by the M-class solar flares on 21 to 22 June.
During this event, the CALLISTO-MEXART station was still under initial configurations and did not detect the event.
Figure
Ionospheric and geomagnetic parameters during 20–25 June 2015:
observed (TEC
Figure
Regional TEC maps constructed for two time moments during the
disturbance (panels
Figure
The geomagnetic storm between 22 and 23 June 2015 discussed here caused
ionospheric disturbances over Mexico. First, let us consider the data from a
single GPS receiver. Figure
Type III solar radio burst detected by CALLISTO-MEXART on 29 September 2015.
One of the products that SCiESMEX offers to its users is the regional TEC
maps, which illustrate TEC distribution over Mexico. Such maps are a useful
instrument for the qualitative estimation of the ionosphere state; see for instance
Type III solar radio burst registered by e-CALLISTO station on
29 September 2015.
The results for 14:00 LT on the day of the maximum positive TEC
disturbance on 22 June 2015 are compared to the results for the same hour on
the quiet geomagnetic day of 3 June 2015 (Fig. For more
details, we have prepared a video of a 38-day period from 24 May 2015 to
30 June 2015 at 24 FPS at
As TEC is an integral parameter that characterizes electron content in the cross unit section from the ground to a GPS satellite, it does not permit precise conclusions to be made about the variations in different ionospheric layers (their peak density and height). The ionospheric sounding data are usually used for that. There are no ionosonde measurements in Mexico at the moment. Installation is a part of our future work. To sum up, the geomagnetic storm that started on 22 June 2015 provoked the ionospheric disturbance over Mexico, which was characterized by the positive phase and then the negative phase. These phases of ionospheric disturbance correlated with the phases of geomagnetic disturbance. The structure of the ionosphere was significantly changed during the geomagnetic storm, which could lead to negative consequences for different technological systems.
Light curve of the type III solar radio burst detected on 29 September 2015 with a signal-to-noise ratio of 32.
The second event that we address in this study is related to the solar radio
burst. It was detected by the CALLISTO-MEXART station and the MEXART radio
telescope at 19:22 UTC on 2 September 2015. This solar radio burst was
associated with a weak M1.1 solar flare that started at 19:20 UTC, peaked
at 19:24, and ended at 19:27 UTC. The closest CME related to this event was
recorded by LASCO at 20:00:04 UTC. According to SWPC/NOAA this particular
CME did not hit the Earth
The solar radio event registered by CALLISTO-MEXART
(Fig.
29 September 2015 records by MEXART (blue curve) and CALLISTO-MEXART (green curve) at approximately 140 MHz. The flux was scaled in order to compare the response of both instruments.
Both instruments, the MEXART radio telescope and the CALLISTO-MEXART, have a common band: approximately 140 MHz. Consequently, both instruments can detect the same events.
We rescaled (
The records show several disturbances in radio communications between 50 and 75 MHz and radio noise between 110 and 170 MHz for around 2 min at the site of observation. This is the first spectrum that shows a radio blackout over Mexico related to SW. This radio blackout could probably affect the frequencies lower than 50 MHz. The local time of the radio burst was about 11:20, close to noon locally. The ionosonde measurements could provide us with information if the HF band (3–30 MHz) was affected by the event. As mentioned above, SCiESMEX currently has no ionosonde measurements in Mexico. The installation of the ionosondes for oblique ionospheric sounding is planned for our future work.
We presented the results of the first joint observations of SW phenomena in Mexico. We addressed two SW events that occurred on 22 June and 29 September 2015. Features of the behavior of SW parameters were obtained with the use of different local instruments installed in Mexico. The main results are the following.
A solar flare was detected by the MEXART radio telescope on 22 June 2015, in
agreement with GOES satellite data. This example proves the possibility of
using MEXART for solar flare detection if the flares occur during the local
daylight hours. For the first time we presented a solar radio event (29 September 2015)
detected by the MEXART radio telescope that is confirmed by the CALLISTO-MEXART
station. The measurements by CALLISTO-MEXART were in accord with other CALLISTO
observations. This proves that both ground-based local instruments (MEXART
and CALLISTO-MEXART) can be used for the monitoring of solar radio bursts
which occur during local daylight hours in Mexico. The advantage of the
MEXART instrument is better sensitivity for such events. Note also that we
report, for the first time, a radio blackout over Mexico related to SW
phenomena. Local cosmic ray data indicate SW phenomena in Mexico. This is due to the
fact that the irregularities in the interplanetary magnetic field, associated
with large-scale solar wind disturbances, deflect the cosmic ray flux
measured in the center of Mexico. For example, a Forbush decrease was
recorded, associated with the passing of the CME detected during the event in
June 2015. Local geomagnetic field variations from 21 to 25 June 2015 caused an intense
ionospheric disturbance over Mexico. Local magnetometer data were in accord
with the variations of the Dst index. The regional
Some lessons can be learned from this first study in order to enhance the SW monitoring and the development of a comprehensive ground-based multi-instrument data set in Mexico. We must increase the number of magnetometers, located at different sites, to have local measurements at different regions in real time. The installation of more CALLISTO stations in Mexico will allow us to understand the effects of radio communications' disruption with more accuracy. For the case of TEC maps computed over Mexican territory, the next step is to improve the spatial resolution of TEC maps by increasing the number of GPS stations available and by bettering our TEC calibration methods. One of the future steps for improving the computations of TEC maps is to implement a homogeneous distribution of GPS stations throughout the ground territory. More detailed analysis could be done with ionospheric sounding data from ionosondes. Thus, ionosonde data are needed to complement both radio blackout studies and ionospheric radio propagation conditions over Mexico. The incorporation of a network of magnetometers and ionosondes in Mexico in the next year will significantly improve the coverage and quality of our space weather data.
Callisto data are publicly and freely available at
The supplement related to this article is available online at:
EA and PV are the technicians in charge of the Callisto station and the MEXART radiotelescope. The processing and data analysis for Callisto MEXART station was developed by VDlL, and EHD. CM is the PI of the e-Callisto network and is taking care of data archiving, pre-processing, image-generation and quality control of CALLISTO data and CM are the people in charge of Callisto data analysis and processing. JAGE, EAR, and JMA are the people on charge of MEXART data analysis. MAS, MR, and ERH are the team focused in Ionosphere analysis. The Cosmic Ray data analysis were performed by XG and JFVG. Geomagnetic analysis and processing was developed by EH, GC, and PCR. The data adqusition in the RICE repository was developed by VDlL and EHD.
The authors declare that they have no conflict of interest.
This article is part of the special issue “Space weather
connections to near-Earth space and the atmosphere”. It is a result of the
6
Thanks are expressed to Catedras CONACyT (CONACyT Fellow) for supporting this work.
Victor De la Luz acknowledges CONACyT 254497 and CONACyT 268273 for Ciencia Basica and Repositorios Institucionales. Maria A. Sergeeva acknowledges the
funding by CONACyT-AEM 2017-01-292700. Julio C. Mejia-Ambriz acknowledges
CONACyT 256033. Pedro Corona-Romero acknowledges CONACyT 254812. SCiESMEX is
partially funded by CONACyT-AEM grant 2017-01-292684, CONACyT LN 293598,
CONACyT PN 2015-173, and DGAPA-PAPIIT IN106916. Ernesto Aguilar-Rodriguez
acknowledges the DGAPA-PAPIIT project (grant: IN101718) and the CONACyT
project (grant: 220981). Mario Rodriguez-Martinez acknowledges DGAPA-PAPIIT
IA 107116 and CONACyT INFR: 253691. The authors express their gratitude to
the NOAA Space Weather Prediction Center (SWPC), Boulder, Colorado, USA, for
providing the analysis software used at SWPC for the operational US-TEC
product to perform TEC calculations for this study. The calculations of the local TEC values are partly based on GPS data provided by the Mexican Servicio
Sismológico Nacional (SSN, 2018; Pérez-Campos et al., 2018), the Trans-boundary,
Land and Atmosphere Longterm Observational and Collaborative Network (TLALOCNet; Cabral-Cano et al., 2018), and SSN-TLALOCNet operated by the Servicio
de Geodesia Satelital (SGS) and SSN at the Instituto de Geofísica, Universidad Nacional Autónoma de México (UNAM) and UNAVCO Inc. We
gratefully acknowledge all the personnel from SSN, SGS, and UNAVCO Inc. for station maintenance, data acquisition, IT support,
and data distribution for these networks. TLALACNet, SSN-TLALOCNet, and related SGS operations are supported by the
National Science Foundation, grant number EAR-1338091, NASA-ROSES NNX12AQ08G,
Consejo Nacional de Ciencia y Tecnologia (CONACyT) projects 253760, 256012, and 2017-01-5955, UNAM Programa de Apoyo a Proyectos de
Investigación e Innovación Tecnológica (PAPIIT) projects IN104213, IN111509, IN109315-3, IN104813-3, and supplemental
support from UNAM Instituto de Geofísica and Centro de Ciencas de la Atmosfera. Thanks are expressed to the
Institute for Astronomy, ETH Zurich, and FHNW Windisch, Switzerland.
Whitham Reeve and Stan Nelson are thanked for providing the observations for the
stations of Alaska and Roswell, New Mexico, in the e-CALLISTO network. The authors
would like to thank Ana Caccavari for providing the magnetic field data from
Teoloyucan Geomagnetic Observatory. The authors also thank Ilya Zhivetiev
from the Institute of Cosmophysical Research and Radio Wave Propagation FEB
RAS and Yury Yasyukevich and Anna Mylnikova from the Institute of
Solar-Terrestrial Physics SB RAS for providing the TayAbsTEC software for
this study (