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In situ observations of interplanetary (IP) coronal mass ejections (ICMEs) and IP shocks are important to study as they are the main components of the solar activity. Hundreds of IP shocks have been detected by various space missions at different times and heliocentric distances. Some of these are followed by an ICME while not for others. In this study, we carry out a statistical analysis of the distributions of plasma and magnetic parameters of the IP shocks. We classify the shocks according to the heliocentric distance, namely from 0.29 to 0.99 au (Helios-1/2); near 1 au (Wind, ACE and STEREO-A/B); and from 1.35 to 5.4 au (Ulysses). We also differentiate the IP shocks into two populations, those with a detected ICME and those without it. We find, as expected, that there are no significant difference in the results from spacecraft positioned at 1 au. Moreover, the distributions of shock parameters, as well as the shock normal have no significant variations with the heliocentric distance. Additionally, we investigate how the number of shocks associated to stream interaction regions (SIRs) increases with distance in proportion of ICME/shocks. From 1 to 5 au, SIRs/ shock occurrence increases slight from 21% to 33%, in contrast ICME/shocks occurrence decreases from 47% to 17%. We find also no indication of an asymmetry induced by the Parker spiral.

Los grados dias calor (GDC) son un indicador del crecimiento de un cultivo, que puede ser usado para inferir la duracion del ciclo del tomate bajo invernadero. Inferir duracion del ciclo de cultivo basado en temperatura supone la posibilidad de programar fechas de siembra, gestion de los recursos y establecer mejores practicas agricolas. El objetivo de este trabajo consistio en simular el comportamiento termico de un invernadero usando Dinamica de Fluidos Computacional (CFD), bajo condiciones ambientales de Navolato, Sinaloa, y Texcoco, Estado de Mexico, para estimar la duracion del ciclo de tomate en funcion de los GDC con fines agronomicos. La prediccion de temperaturas al interior del invernadero se realizo mediante un modelo numerico basado en CFD. Los resultados de las simulaciones fueron utilizados para cuantificar GDC y estimar la duracion del ciclo del tomate con base en su requerimiento de temperatura. Se estimaron en Navolato, Sinaloa, 5 772.01, 6 128.34 y 6 411.93 GDC anuales en la entrada, centro y salida del invernadero, respectivamente. El incremento en la acumulacion anual de GDC favorece los ciclos cortos y, en consecuencia, aumenta el numero de ciclos por ano (mas de dos ciclos de tomate). En Texcoco, Estado de Mexico, se estimaron 2 447.94, 2 803.5 y 3 076.09 GDC anuales, en la entrada, centro y salida del invernadero, respectivamente, lo que limita cultivar de manera natural solo un ciclo. No obstante, si se favorecen las temperaturas del ultimo tercio del invernadero, se estima se puedan cultivar dos ciclos.

Los grados días calor (GDC) son un indicador del crecimiento de un cultivo, que puede ser usado para inferir la duración del ciclo del tomate bajo invernadero. Inferir duración del ciclo de cultivo basado en temperatura supone la posibilidad de programar fechas de siembra, gestión de los recursos y establecer mejores prácticas agrícolas. El objetivo de este trabajo consistió en simular el comportamiento térmico de un invernadero usando Dinámica de Fluidos Computacional (CFD), bajo condiciones ambientales de Navolato, Sinaloa, y Texcoco, Estado de México, para estimar la duración del ciclo de tomate en función de los GDC con fines agronómicos. La predicción de temperaturas al interior del invernadero se realizó mediante un modelo numérico basado en CFD. Los resultados de las simulaciones fueron utilizados para cuantificar GDC y estimar la duración del ciclo del tomate con base en su requerimiento de temperatura. Se estimaron en Navolato, Sinaloa, 5 772.01, 6 128.34 y 6 411.93 GDC anuales en la entrada, centro y salida del invernadero, respectivamente. El incremento en la acumulación anual de GDC favorece los ciclos cortos y, en consecuencia, aumenta el número de ciclos por año (más de dos ciclos de tomate). En Texcoco, Estado de México, se estimaron 2 447.94, 2 803.5 y 3 076.09 GDC anuales, en la entrada, centro y salida del invernadero, respectivamente, lo que limita cultivar de manera natural sólo un ciclo. No obstante, si se favorecen las temperaturas del último tercio del invernadero, se estima se puedan cultivar dos ciclos.

The Mexican Array Radio Telescope (MEXART) is a transit instrument mainly dedicated to performing Interplanetary Scintillation (IPS) observations with a central operating frequency of 139.65 MHz. T...

Vapor pressure deficit (VPD) can be used as an indicator to schedule greenhouse irrigation. VPD can be estimated as a function of relative humidity (RH) and temperature (T). The objective of this work was to analyze spatial variation in VPD as an indicator of water stress influenced by concentration of water vapor and intensity of near infrared (NIR). The study was carried out in an empty three-span sawtooth greenhouse with natural ventilation under the local climate in Montecillo, Mexico, these findings established a base value to analyze greenhouse field conditions prior to the influence from a crop. The experimental phase consisted of recording data (3 February 2019–24 February 2019) on temperature, humidity, solar radiation, and wind speed, which were used for developing a model in computational fluid dynamics (CFD). Then, this model was used to estimate VPD, considering changes in mass fraction of water vapor and the intensity of NIR. Scenarios with 50, 70, and 90% external RH were evaluated. It was found that without a crop, temperature was not affected by the variation in the mass fraction of water vapor and the intensity of NIR in the simulated scenarios, each of which generated a thermal gradient within the range of 4 °C. When considering the scenario of 90% external RH, we found the best VPD range along the greenhouse (2–3 kPa) that would be a favorable field condition for crops. Differences between VPD with and without a crop can be used to estimate the water quantity needs for crop growth based on the climate variables examined in this study, where higher VPD values require more water for irrigation.

Possible ionospheric effects of the Morelian meteoroid that passed and exploded over Mexico on 19 February 2020 (18 February 2020 local time) were estimated. The meteoroid trajectory, velocity and time of occurrence were calculated based on outdoor camera records. Modeling was used to estimate the meteoroid initial diameter, density, mass, velocity, energy and their change during its flight in the atmosphere. The ensemble of ionospheric scintillation indices calculated from the high-rate GNSS data and the filtered slant Total Electron Content data were used to reveal the presence of ionospheric disturbances generated by shock waves excited by the meteoroid flight and explosion. The first ionospheric responses to phenomena accompanying the meteoroid were detected (2.5–3.5) min after the explosion. The disturbances were attenuated quickly with distance from their source and were rarely recorded by GNSS receivers located more than 600 km from the meteoroid explosion site. The ionospheric disturbances of intermediate-scale, small-scale, shock-acoustic-wave-scale and sometimes medium-scale were revealed. The detected disturbances corresponded to the range of acoustic-gravity waves. An asymmetry of the disturbance manifestation in different directions was observed. The obtained results are in accordance with results of the observation of other meteoroids. Although the object was smaller and of less energy than other known meteoroids, it is an interesting case because, to the best of our knowledge, it isthe first known to us low-latitude meteoroid with the detected ionospheric effects.

We analyze Type II radio emissions observed by the Radio and Plasma Waves instrument onboard Wind to determine the emission region in shock fronts, using the blast wave reconstruction technique. Our results suggest that the processes of emission of a Type II radio burst occur not only in the upstream region of the shock, i.e. the region that precedes the collision, but also that there must be an emission of the material that has been compressed, as well as of the material that is in the compression region within the structure of the shock itself.

In Mexico, there are regions where the temperature drops below the minimum threshold for tomato cultivation (10 °C), requiring the implementation of auxiliary equipment to heat greenhouse air. The objective of this work was to estimate the energy consumption necessary to maintain climate requirements of a greenhouse located in Texcoco, State of Mexico, by using a model of energy balance implemented on Computational Fluid Dynamics (CFD) simulations. The temperature prediction relied on a numerical model based on CFD, proposing a benchmarking on the position and direction of the heater to estimate its effect on the thermal distribution. Results indicated that heater operation on January 2019, a power of 85.56 kW was needed to keep the greenhouse at 12 °C. Also, simulations indicated that electric heater used was not enough to get a homogeneous temperature inside the greenhouse. To achieve well-distributed thermal conditions, it was necessary to consider both the direction and position of heaters. Consequently, airflow direction became more important than height of the heater in order to homogenize the greenhouse area, given that the thermal gradient was reduced due to reverse heat flows.

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 stream interaction regions (SIRs) are generated in the interplanetary medium when a fast solar wind stream overtakes a slower one. If these large-scale phenomena interact with the Earth's magnetosphere, they can give rise to geomagnetic storms (GSs). Their geoeffectivity is measured using magnetic indices at different latitudes. In this study we analyzed the geoeffectiveness of 20 GSs that were generated by SIRs during the period of 2007 to 2008, and observed by the ACE, WIND and STEREO-A/B spacecraft. We compared the geomagnetic response to the SIRs-magnetosphere interaction employing different geomagnetic indices at low, middle and high latitudes. The geoefectiveness was 50%, 55%, and 90% using the criteria of the aa, Kp, and SYM-H indices, respectively. We found that in most cases the maximum intensity of each index was in the weak to moderate range. According to the SYM-H index, a 10%, 60%, and 10% of the forward shocks were followed by quiet, weak, and moderate GSs, respectively. The 10% and 20%, however, were followed by minor and moderate GSs, respectively, according to the Kp index. We analyzed the geoeffective region within the SIRs with respect to the relative position of the stream interface (SI). For 75% of GSs, their maximum intensity occurred during the disturbed fast solar wind (after the passing of the SI), which would be related to the efficiency of a SIR. The time difference Δt between the passing of the SI and the maximum intensity in each index was less than 36 hours.

Tesis (Doctor en Ciencias y Tecnología del Agua) -- Instituto Mexicano de Tecnología del Agua. Coordinación de Desarrollo Profesional e Institucional. Subcoordinación de Posgrado. La evaluación del impacto de las variables climáticas en un invernadero ayuda a determinar ciclos de cultivos y también al uso estratégico de insumos. Técnicas experimentales, numéricas y analíticas se han desarrollado para el estudio del ambiente en un invernadero con el propósito de predecir calidad y cantidad de producción agrícola. Este trabajo de investigación analiza y aporta información sobre la función que tiene el clima diurno y nocturno, en conjunto con un análisis espacial en un invernadero. En particular, la temperatura como variable prioritaria del clima es utilizada para definir gradientes térmicos del invernadero, y a partir de allí estimar la duración del ciclo de producción de tomate en función de grados días calor. También, esta investigación evaluó el efecto que tienen los calefactores eléctricos sobre la homogeneización de temperatura en periodos críticos de baja temperatura para producción de tomate. Adicionalmente, se han estudiado las consecuencias de condiciones de operación de un invernadero en la concentración de vapor de agua e intensidad del infrarrojo cercano.

The Mexican Radio Telescope (MEXART) is a regular aperture array consisting of 4096 full wavelength dipoles whose primary scientific objective is to carry out interplanetary scintillation observations of solar wind disturbances, located in the state of Michoacan in Mexico. The current system uses a Butler Matrix to generate 16 fixed beams, however calibration of the instrument is a problematic issue, resulting in a loss in sensitivity which is impeding the telescope from reaching its potential. In order to improve the performance of the telescope the RF system is going to be converted to a digital one. Signals from the receiving elements, after undergoing conditioning, are transported to a digital backend consisting of FPGA-based digital boards which perform digitisation, channelization and packetization of the channelized data. The beams are then generated on a GPU implementation of a frequency domain beamforming running on a compute server. The antenna signals will routinely be calibrated using transits of strong calibrator sources. This paper presents the design and implementation of the new digital backend, which is planned on being deployed in summer 2019.

Legislative modifications of the General Civil Protection Law in Mexico in 2014 included specific references to space hazards and space weather phenomena. The legislation is consistent with United Nations promotion of international engagement and cooperation on space weather awareness, studies and monitoring. These internal and external conditions motivated the creation of a space weather service in Mexico. The Mexican Space Weather Service (SCiESMEX in Spanish) (www.sciesmex.unam.mx) was initiated in October 2014 and is operated by the Institute of Geophysics at the Universidad Nacional Autonoma de Mexico (UNAM). SCiESMEX became a Regional Warning Center of the International Space Environment Services (ISES) in June 2015. We present the characteristics of the service, some products and the initial actions for developing a space weather strategy in Mexico. The service operates a computing infrastructure including a web application, data repository and a high-performance computing server to run numerical models. SCiESMEX uses data of the ground-based instrumental network of the National Space Weather Laboratory (LANCE), covering solar radio burst emissions, solar wind and interplanetary disturbances (by interplanetary scintillation observations), geomagnetic measurements, and analysis of the total electron content (TEC) of the ionosphere (by employing data from local networks of GPS receiver stations).

Made available in DSpace on 2019-10-04T12:34:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-12-01 CONACyT Posgrado en Ciencias de la Tierra, UNAM Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) CONACYT CONACYT-AEM DGAPA-PAPIIT Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) DGAPA-PAPIIT project NSF National Science Foundation NASA-ROSES UNAM-PAPIIT The present work is the first of a two-part weather study of the ionospheric Total Electron Content (TEC), based on data collected by four ground-based Global Navigation Satellite System networks that cover the whole Latin America from the Patagonia to the north of Mexico. From the best of our knowledge, the maps presented here are the first TEC maps obtained using ground-based data that covers the entire Latin America region, which represent an advance to the space weather monitoring and forecasting of the ionosphere. This work provides a qualitative and quantitative daytime analysis of the ionospheric TEC variation, which encompasses: (a) the response of TEC to the solar flux at midday; (b) the seasonal variation of TEC in different latitudinal ranges; and (c) the North-South asymmetry of TEC over Latin America. The response to the solar flux is based on day-to-day TEC variations during two periods of different solar activity conditions: 2011 (ascending phase) and 2014 (maximum). The approximations of meridional wind component derived from Horizontal Wind Model-14 model and h(m)F(2) obtained from International Reference Ionosphere model were used. Equinoctial asymmetries with an opposite configuration in high and moderate solar activity were identified in the TEC variation. For 2011, it was related to the solar flux change. However, in 2014, according to the h(m)F(2) variation, the influence of neutral wind becomes dominant. Among the results, we highlight an absence of winter anomaly in the Northern Hemisphere in 2014 and a stronger annual anomaly for latitudes under -20 degrees. Univ Autonoma Nuevo Leon, Fac Ciencias Fis Matemat, LANCE, Monterrey, Mexico Inst Nacl Pesquisas Espaciais, Sao Jose Dos Campos, Brazil Univ Nacl Autonoma Mexico, Inst Geofis, Unidad Michoacan, LANCE, Morelia, Michoacan, Mexico Inst Fed Educ Ciencia & Tecnol Sao Paulo, Jacarei, Brazil MIT, Haystack Observ, Westford, MA 01886 USA Univ Nacl Autonoma Mexico, Unidad Morelia, Escuela Nacl Estudios Super, Morelia, Michoacan, Mexico Univ Nacl Autonoma Mexico, Inst Geofis, Unidad Michoacan, CONACyT, Morelia, Michoacan, Mexico Univ Estadual Paulista, Dept Cartog, Presidente Prudente, Brazil Univ Estadual Paulista, Dept Cartog, Presidente Prudente, Brazil CNPq: 303643/2017-0 CONACYT: LN 293598 CONACYT: PN 2015-173 CONACYT: 220981 CONACYT: 253760 CONACYT: 256012 CONACYT: 2017-01-5955 CONACYT: 253691 CONACYT-AEM: 2017-01-292684 DGAPA-PAPIIT: IN106916 DGAPA-PAPIIT: IN104213 DGAPA-PAPIIT: IN109315-3 DGAPA-PAPIIT: IN104818-3 FAPESP: 2014/11198-9 CAPES: 1622967 DGAPA-PAPIIT project: IN101718 NSF: AGS-1242204 National Science Foundation: EAR-1338091 NASA-ROSES: NNX12AQ08G UNAM-PAPIIT: IA107116 UNAM-PAPIIT: IN118119

With the advent of the Navigation Satellites the Total Electron Content (TEC) has become one of the main parameters of the ionosphere. This is the result of a continuous TEC monitoring and rather dense network of GPS receivers. For Mexican region having no ionosondes the use of TEC for ionospheric conditions studies and monitoring has a special value. To study the behaviour of TEC and for its applied aspects two types of source-files are used worldwide: IONEX (global maps) and RINEX (local data) depending on the task solved. Magnetometer and satellite data from CHAMP and DMSP were involved in the analysis. First, benefits and limitations of TEC derived from both types of files are discussed in regard to the estimation of the ionosphere state in the Mexican region. Second, using both methods the specific features of diurnal, seasonal and annual patterns in TEC behaviour over Mexico were revealed, among which are the shift of the diurnal maximum to 14 LT, dependence on solar activity, high probability of night-time enhancements, presence of annual and winter anomalies. Third, it was revealed that the positive short-lived TEC enhancements are characteristic for Mexican region. They may occur even under quiet conditions. The answer is given what part of the ionosphere is responsible for TEC change during these positive disturbances. The results for Mexico were compared to the neighboring regions and South-East zone.

The power spectra of intensity fluctuations in interplanetary scintillation (IPS) observations can be used to estimate solar-wind speeds in the inner heliosphere. We obtain and then compare IPS spectra from both wavelet and Fourier analyses for 12 time series of the radio source 3C48; these observations were carried out at Japan’s Solar-Terrestrial Environment Laboratory (STEL) facility, at 327 MHz. We show that wavelet and Fourier analyses yield very similar power spectra. Thus, when fitting a model to spectra to determine solar-wind speeds, both yield comparable results. Although spectra from wavelet and Fourier closely match each other for solar-wind speed purposes, those from the wavelet analysis are slightly cleaner, which is reflected in an apparent level of intensity fluctuations that is enhanced, being ≈ 13 % higher. This is potentially useful for records that show a low signal-to-noise ratio.

Interplanetary scintillation (IPS) is used to probe solar wind speeds in the inner heliosphere by applying either of two generalized data-analysis techniques: model fitting to power spectra (MFPS) from a single station, or cross-correlation functions (CCF) produced by cross-correlating two simultaneous IPS time series from separate stations. The MEXican Array Radio Telescope (MEXART), observing at 140 MHz, is starting to use an MFPS technique. Here we report the first successful solar wind speed determinations with IPS observations by MEXART. Three stations of the Solar-Terrestrial Environment Laboratory (STEL), observing at 327 MHz, use a CCF, and an MFPS technique is also used at one of these sites. We here analyze data from MEXART and from one antenna of STEL to obtain solar wind speeds using an MFPS technique from a single station. The IPS observations were carried out with radio source 3C48 during Solar Cycle 24. The MFPS method we describe here is tested by comparing its obtained speeds with those from the STEL CCF technique. We find that the speeds from the two techniques generally agree within the estimated errors.

The interplanetary scintillation (IPS) technique is a remote-sensing method for monitoring solar-wind perturbations. The Mexican Array Radio Telescope (MEXART) is a single-station instrument operating at 140 MHz, fully dedicated to performing solar-wind studies employing the IPS technique. We report MEXART solar-wind measurements (scintillation indices and solar-wind velocities) using data obtained during the 2013 and 2014 campaigns. These solar-wind measurements were calculated employing a new methodology based on the wavelet transform (WT) function. We report the variation of the scintillation indices versus the heliocentric distance for two IPS sources (3C48 and 3C147). We found different average conditions of the solar-wind density fluctuations in 2013 and 2014. We used the fittings of the radial dependence of the scintillation index to calculate g-indices. Based on the g-index value, we identified 17 events that could be associated with strong compression regions in the solar wind. We present the first ICME identifications in our data. We associated 14 IPS events with preceding CME counterparts by employing white-light observations from the Large Angle and Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. We found that most of the IPS events, detected during the solar maximum of Cycle 24 were associated with complex CME events. For the IPS events associated with single CME counterparts, we found a deceleration tendency of the CMEs as they propagate in the interplanetary medium. These results show that the instrument detects solar-wind disturbances, and the WT methodology provides solar-wind information with good accuracy. The MEXART observations will complement solar-wind IPS studies using other frequencies, and the tracking of solar-wind disturbances by other stations located at different longitudes.

Interplanetary scintillation (IPS) observations are useful to remotely sense the inner heliosphere. We present a new technique to analyze IPS observations using a wavelet transform (WT) function. This technique allows us to derive, in a straightforward way, a simple method to obtain the scintillation index (m). We tested this WT technique to analyze IPS observations obtained by the Solar-Terrestrial Environment Laboratory (STEL) radio telescope. The analysis of the m index of the radio source 3C48 detected by STEL over the year 2012 shows the expected decrease with solar elongation reported in previous studies. The WT technique has a great potential for future solar wind studies using IPS observations from contemporary radio telescopes.

Coronal mass ejections (CMEs) are large-scale eruptive events in the solar corona. Once they are expelled into the interplanetary (IP) medium, they propagate outwards and “evolve” interacting with the solar wind. Fast CMEs associated with IP shocks are a critical subject for space weather investigations. We present an analytic model to study the heliocentric evolution of fast CME/shock events and their association with type II radio-burst emissions. The propagation model assumes an early stage where the CME acts as a piston driving a shock wave; beyond this point the CME decelerates, tending to match the ambient solar wind speed and its shock decays. We use the shock speed evolution to reproduce type II radio-burst emissions. We analyse four fast CME halo events that were associated with kilometric type II radio bursts, and in-situ measurements of IP shock and CME signatures. The results show good agreement with the dynamic spectra of the type II frequency drifts and the in-situ measurements. This suggests that, in general, IP shocks associated with fast CMEs evolve as blast waves approaching 1 AU, implying that the CMEs do not drive their shocks any further at this heliocentric range.

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 report the results of a multi-instrument, multi-technique, coordinated study of the solar eruptive event of 13 May 2005. We discuss the resultant Earth-directed (halo) coronal mass ejection (CME), and the effects on the terrestrial space environment and upper Earth atmosphere. The interplanetary CME (ICME) impacted the Earth’s magnetosphere and caused the most-intense geomagnetic storm of 2005 with a Disturbed Storm Time (Dst) index reaching −263 nT at its peak. The terrestrial environment responded to the storm on a global scale. We have combined observations and measurements from coronal and interplanetary remote-sensing instruments, interplanetary and near-Earth in-situ measurements, remote-sensing observations and in-situ measurements of the terrestrial magnetosphere and ionosphere, along with coronal and heliospheric modelling. These analyses are used to trace the origin, development, propagation, terrestrial impact, and subsequent consequences of this event to obtain the most comprehensive view of a geo-effective solar eruption to date. This particular event is also part of a NASA-sponsored Living With a Star (LWS) study and an on-going US NSF-sponsored Solar, Heliospheric, and INterplanetary Environment (SHINE) community investigation.

Fast CME/shocks propagating in the interplanetary medium can generate kilometric Type II (km-TII) radio emissions at the local plasma frequency and/or its harmonic, so these radio emissions provide a means of remotely tracking CME/shocks. We apply a new analysis technique, using the frequency drift of km-TII spectrum obtained by the Thermal Noise Receiver (TNR) of the WIND/WAVES experiment, to infer, at some adequate intervals, the propagation speed of six CME/shocks. We combine these results with previously reported speeds from coronagraph white light and interplanetary scintillation observations, and in-situ measurements, to study the temporal speed evolution of the six events. The speed values obtained by the km-TII analysis are in a reasonable agreement with the speed measurements obtained by other techniques at different heliocentric distance ranges. The combination of all the speed measurements show a gradual deceleration of the CME/shocks as they propagate to 1 AU. This new technique can be useful in studying the evolution of fast CME/shocks when adequate intervals of km-TII emissions are available.

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.

We present a physical methodology to reconstruct the trajectory of interplanetary shocks using type II radio emission data. This technique calculates the shock trajectory assuming that the disturbance propagates as a blast wave in the interplanetary medium. We applied this Blast Wave Reconstruction (BWR) technique to analyze eight fast Earth-directed ICMEs/shocks associated with type II emissions. The technique deduces a shock trajectory that reproduces the type II frequency drifts, and calculates shock onset speed, shock transit time and shock speed at 1 AU. There were good agreements comparing the BWR results with the type II spectra, with data from coronagraph images, in situ measurements, and interplanetary scintillation (IPS) observations. Perturbations on the type II data affect the accuracy of the BWR technique. This methodology could be applied to track interplanetary shocks causing TII emissions in real-time, to predict the shock arrival time and shock speed at 1 AU., Comment: Submitted to Solar Physics. In revision

We present a study which focuses on the speed evolution of a coronal mass ejection (CME)/shock associated with a type II radio burst observed on January 25, 2007. The type II burst feature had a multi-spacecraft coverage, being detected by the Wind/WAVES and the STEREO/WAVES radio instruments in the frequency range of 14 MHz to 90 kHz. The CME associated with the type II radio burst was observed by the SOHO/LASCO and the STEREO/SECCHI coronographs. Ground-based radio observations of the metric type II burst counterpart were obtained by the Bruny Island Radio Spectrometer (BIRS) in the frequency range of 40 MHz to 25 MHz. We analyzed the combined white-light and radio observations to infer the speed evolution of the CME/shock event. The CME/shock speed from the different data sets shows a significant deceleration near to the Sun followed by a slow and gradual deceleration in the interplanetary medium, which is consistent with the expected evolution of fast CME/shocks. Multi-spacecraft and combined white-li...

[1] We investigate the characteristics of 9 interplanetary shocks associated with stream interaction regions observed by both STEREO-A and STEREO-B spacecraft during the years 2007–2008. Interplanetary shocks modify the plasma both upstream and downstream of the front shock. As they propagate, interplanetary shocks encounter solar wind with different characteristics (density, velocity) and different orientations of ambient magnetic field relative to the shock normal. Thus, it is interesting to compare dual observations of stream interaction shocks at the locations of the two spacecraft to determine the role of these parameters in controlling both the structure at the shock but also in the regions upstream and downstream from the shock. The range of shock normal angle (ΘBn) values observed by spacecraft covered the range from ∼20° to ∼81°. The largest difference in ΘBn for the same shock observed at two different longitudinal locations was ∼39°. The shock magnetosonic Mach numbers covered the range of ∼1.1 to ∼2.2, having a largest change for the same shock of ∼0.9. The jump in the field magnitude, i.e., the ratio of downstream magnetic field intensity to upstream magnetic field intensity (Bd/Bu), ranged from ∼1.1 to ∼2.25. The largest difference in the jump in field magnitude for the same shock at two different locations was ∼0.72. These variations with longitude of shock properties observed with the STEREO dual mission show the non-homogeneous character of the plasma in the heliosphere, and they need to be taken into account to understand in detail how these shocks modify the solar wind, and affect the acceleration processes of energetic particles in the solar wind.

[1] We present a study on the spectral properties of interplanetary type II radio bursts observed by the Radio and Plasma Wave (WAVES) experiment on board the Wind spacecraft. We investigated the relative bandwidth of the type II radio bursts observed by WAVES from 1997 up to 2003. We obtained three sets of events, based on the frequency domain of occurrence: 109 events in the low-frequency domain (30 KHz to 1000 kHz, detected by the RAD1 receiver), 216 events in the high-frequency domain (1-14 MHz, observed by the RAD2 receiver), and 73 events that spanned both domains (RAD1 and RAD2). Statistical results show that the average bandwidth-to-frequency ratio (BFR) was 0.28 ± 0.15, 0.26 ± 0.16, and 0.32 ± 0.15 for RAD1, RAD2, and RAD1 + RAD2, respectively. We compared our results with those obtained for ISEE-3 type II bursts and found a difference in the average BFR, which seems to be due to a selection effect. The BFR of the WAVES type II bursts is similar to that of metric type II bursts reported in published works. This suggests that the BFR is a universal characteristic, irrespective of the spectral domain. Finally, we also studied the BFR evolution with heliocentric distance using white-light observation of the associated coronal mass ejections. We found that the BFR remains roughly constant in the SOHO/LASCO field of view (i.e., from 2.1 to 32 solar radii), while the bandwidth itself decreases.

The Mexican Array Radio Telescope (MEXART) consists of a 64×64 (4096) full-wavelength dipole antenna array, operating at 140 MHz, with a bandwidth of 2 MHz, occupying about 9660 square meters (69 m × 140 m) (http://www.mexart.unam.mx). This is a dedicated radio array for Interplanetary Scintillation (IPS) observations located at latitude 19°48′N, longitude 101°41′W. We characterize the performance of the system. We report the first IPS observations with the instrument, employing a Butler Matrix (BM) of 16×16 ports, fed by 16 east – west lines of 64 dipoles (1/4 of the total array). The BM displays a radiation pattern of 16 beams at different declinations (from −48, to +88 degrees). We present a list of 19 strong IPS radio sources (having at least 3σ in power gain) detected by the instrument. We report the power spectral analysis procedure of the intensity fluctuations. The operation of MEXART will allow us a better coverage of solar wind disturbances, complementing the data provided by the other, previously built, instruments.