Search

We present an analysis of ionospheric disturbances at a location in Mexico (dip latitude: 28 ° , geographic latitude: 19 ° N) using two different parameters: ionospheric scintillation (IONS) and Total Electron Content (TEC). This study employs observations during 2014–2015 of astronomical radio sources at 140 MHz obtained by the MEXican Array Radio Telescope (MEXART) and TEC values from Global Ionospheric Maps data. To identify the ionospheric disturbances two indices were used: the wavelet IONS index based on the wavelet transform function of MEXART data and the ionospheric W-index based on the deviation of TEC. A set of 55 wavelet IONS events and 63 W-index events were identified in this interval. We analyzed the association of theses events with solar flares that occurred around the solar zenith and/or geomagnetic storms. During this period, it was observed an incidence of daytime IONS at hours around the solar zenith. Some possible associations with solar flares were found. The preliminary results pointed out that, for this period, daytime scintillations could be linked to the occurrence of Es b -layers. In addition, most of the W-index events were possibly related to geomagnetic storms. We found that the majority of these geomagnetic storms were minor and moderate storms and were characterized by steeper falls of Dst. This first analysis revealed that wavelet methodology is useful in identifying and analyzing ionospheric disturbances. Also, MEXART observations provide a good tool for performing IONS studies at mid latitudes.

The tracking of large-scale interplanetary (IP) disturbances traveling from the Sun to the Earth is a key issue in space weather studies. The Mexican Array Radio Telescope (MEXART) applies the Interplanetary Scintillation (IPS) technique to detect these solar wind disturbances and it will participate in a global warning network of space weather forecasting. We describe the data storage and computational processes carried out to manage the instrument’s real time data. These procedures are important for the MEXART calibration, operation and the scientific data reduction.

We study the magnetic structure and charge state ratio of interplanetary coronal mass ejections (ICMEs) observed by ACE and Wind spacecraft. Measurements of abundances and charge state ratio of heavy ions (e.g. O 7+ /O 6+ ,C 6+ /C 5+ , and Mg 10+ /O 6+ ) in the plasma as well as magnetic field structure are important tracers for physical conditions and processes in the source regions of ICMEs. We used ion composition (from ACE), plasma (from Wind) and magnetic field (from Wind and ACE) data from 1998 to 2002. Using the low proton temperature criterion, a common plasma signature of ICMEs, we identified 154 events which include magnetic clouds, non-cloud ejecta and complex ICMEs. The latter one refers to compound events resulting from the overtaking of successive ICMEs which can include both magnetic clouds and non-cloud ejecta. We find that there is a close relationship between the increase in the charge state ionization factor and the magnetic structure of ICMEs. Events with magnetic cloud topology show higher QO7þ=O6þ and QMg10þ=O6þ charge state ratios than those with non-magnetic cloud structure. However, both magnetic cloud and non-cloud events show an increase in these ratios when compared with the ambient solar wind. In contrast, perhaps due to instrumental effects, the charge state ratio QC6þ=C5þ for all events does not show a real enhancement when compared with the ambient solar wind. The difference in ionization states between non-cloud ejecta and magnetic clouds is more pronounced in fast solar wind than when events are embedded in slow wind. 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.