Interplanetary Disturbances Research Articles

Long-term variations of solar magnetic fields derived from geomagnetic data

Sunspots are dark spots on the solar surface associated with strong magnetic fields. The number, area, and brightness of sunspots are supposed to reflect the intensity of the solar magnetic fields and are often used as proxies for their long-term variations. However, the correlations between the sunspot parameters and solar magnetic fields are not constant, and the causes and the time profiles of the variations in these correlations are not quite clear. Therefore, the sunspot data alone cannot be used as proxy for deriving the variations of the sunspot magnetic fields for periods when no instrumental measurements are available. But the Earth is a sort of a probe reacting to interplanetary disturbances which are manifestation of the solar magnetic fields, so records of the geomagnetic activity can be used as diagnostic tools for reconstructing past solar magnetic fields evolution. In the present study we combine sunspot and geomagnetic data to estimate the long-term variations of sunspot magnetic fields.

Effect of Interplanetary Disturbances and Geomagnetic Activities on Relativistic Electrons at Geosynchronous Orbit

AbstractUsing hourly averaged data of > 2 MeV electron fluxes measured with GOES 7/9/10/11 satellites during 1988–2010, this paper investigates statistically conditions of solar wind and geomagnetic activities during relativistic electrons flux (Fe) enhancements, and describes the dependence of relativistic electrons at geosynchronous orbit (GEO) on local time, magnetic storms. The results are as follows: (1) The local time dependence of GEO relativistic electrons is influenced by solar wind and geomagnetic activities. The noon/midnight electron flux ratio grows with increasing solar wind velocity (Vsw). On conditions of the Dst index above −50 nT, relativistic electrons show regular variation with local time, while during storms with Dst< −50 nT, the maximum electrons flux may not be measured at local noon. During the declining phase of a solar cycle relativistic electron fluxes approaching maximum, Vsw, the Kp index and the cube root of solar wind density (N) show better correlations with electron fluxes after 39∼57 h, 57∼80 h and 12∼24 h, respectively. (2) Before about two years of solar minimum and near the equinoxes, occurrence frequencies of intense relativistic electron flux enhancement events, in which the daily maximum relativistic electron flux Femax ≥ 104 pfu increased, while weaker events with 104 > Femax ≥ 103 pfu exhibited no such solar cycle and seasonal dependences. For most intense events, relativistic electron fluxes begin to increase during main phases of magnetic storms, while for weaker events, relativistic electron fluxes tend to increase during recovery phases. (3) The solar wind density shows as a good indicator of subsequent relativistic electron activities. For most electron flux enhancement events, relativistic electron flux decreased to its minimum after 0∼1 days of the maximum solar wind density, Nmax, while approaching the maximum after 0∼2 days of the minimum solar wind density, Nmin. (4) Above 90% of relativistic electron events occurred on conditions of high‐speed solar wind and geomagnetic disturbances, which are as follows: Vswmax > 516 km/s, Dstmin < −31 nT, Nmin < 2.8 cm−3, Nmax > 14.1 cm−3, Bzmin < −2.9 nT, AEmax > 698 nT. (5) For all magnetic storms, occurrence probability of daily maximum electron flux above 103 pfu after Dstmin, is about 53%, the percent of intense, weak events being 36%, 64%, respectively, which is hardly affected by intensities of storms. During storms, solar wind velocity, density, and the AE index are important indicators for subsequent relativistic electron activities.

Coronal mass ejections in July 2005 and an unusual heliospheric event

Using the events in July 2005 as an example, the causes and peculiarities of Forbush effects produced by solar sources remote from the central zone are discussed. The event in question differs from other effects observed at the periphery of interplanetary disturbances by strong variations in cosmic rays on the background of weak disturbances in the solar wind and magnetic field of the Earth. The cloud of magnetized plasma ejected from the Sun was large and fast, but it passed to the west from the Sun-Earth line. According to performed estimates, the mass of the ejected substance was close to the upper boundary of mass for coronal mass ejections (CMEs). Anomalous parameters and high modulation capability of the formed solar wind disturbance are explained, in particular, by the fact that it combined several CMEs and that the last fast disturbance was prepared by a series of impulsive events in the active region of the Sun. Usually, such a great mass is ejected directly after the main energy release in strong solar flares. In the given case, a powerful MHD disturbance occurred approximately half an hour after a maximum of hard X-ray burst under the conditions when gas pressure in the flare loops became close to magnetic pressure, which was just a premise of the largescale ejection.

Study on Relationship between Power Grid GIC (Geomagnetically Induced Currents) and Interplanetary Disturbances

Geomagnetically induced currents (GIC) are very harmful to the power system and caused by the changes of geomagnetic field. The changing magnetic fields originate from the interplanetary space. Therefore, recognizing the relationship between GIC and interplanetary disturbances is significant for the prediction of GIC. In this paper, we collected 35 GIC events during 1999-2005 and the corresponding interplanetary data observed by ACE satellite to analyze the correlations of various interplanetary parameters with GIC. The results show that there is positive correlation between GIC amplitudes and interplanetary parameters. As a single factor, solar wind dynamic pressure (Pk) correlates best with GIC, while interplanetary electric field (Ey) and interplanetary magnetic field (|B|) also correlate well with GIC. In addition, we investigated the relationships between interplanetary parameters and GIC amplitudes for different intensities (GIC>10A, GIC>20A). Comprehensive analysis shows that Pk and Ey are the most closely parameters related to GIC.

Kinematics of Interacting ICMEs and Related Forbush Decrease: Case Study

We study heliospheric propagation and some space weather aspects of three Earth-directed interplanetary coronal mass ejections (ICMEs), successively launched from the active region AR 11158 in the period 13 – 15 February 2011. From the analysis of the ICME kinematics, morphological evolution, and in situ observations, we infer that the three ICMEs interacted on their way to Earth, arriving together at 1 AU as a single interplanetary disturbance. Detailed analysis of the in situ data reveals complex internal structure of the disturbance, where signatures of the three initially independent ICMEs could be recognized. The analysis also reveals compression and heating of the middle ICME, as well as ongoing magnetic reconnection between the leading and the middle ICME. We present evidence showing that the propagation of these two, initially slower ICMEs, was boosted by the fastest, third ICME. Finally, we employ the ground-based cosmic ray observations, to show that this complex disturbance produced a single cosmic ray event, i.e., a simple Forbush decrease (FD). The results presented provide a better understanding of the ICME interactions and reveal effects that should be taken into account in forecasting of the arrival of such compound structures.

Interplanetary Disturbances Affecting Space Weather

AbstractThe Sun somehow accelerates the solar wind, an incessant stream of plasma originating in coronal holes and some, as yet unidentified, regions. Occasionally, coronal, and possibly sub-photospheric structures, conspire to energize a spectacular eruption from the Sun which we call a coronal mass ejection (CME). These can leave the Sun at very high speeds and travel through the interplanetary medium, resulting in a large-scale disturbance of the ambient background plasma. These interplanetary CMEs (ICMEs) can drive shocks which in turn accelerate particles, but also have a distinct intrinsic magnetic structure which is capable of disturbing the Earth's magnetic field and causing significant geomagnetic effects. They also affect other planets, so they can and do contribute to space weather throughout the heliosphere. This paper presents a historical review of early space weather studies, a modern-day example, and discusses space weather throughout the heliosphere.

Geomagnetic response to solar and interplanetary disturbances

The space weather discipline involves different physical scenarios, which are characterised by very different physical conditions, ranging from the Sun to the terrestrial magnetosphere and ionosphere. Thanks to the great modelling effort made during the last years, a few Sun-to-ionosphere/thermosphere physics-based numerical codes have been developed. However, the success of the prediction is still far from achieving the desirable results and much more progress is needed. Some aspects involved in this progress concern both the technical progress (developing and validating tools to forecast, selecting the optimal parameters as inputs for the tools, improving accuracy in prediction with short lead time, etc.) and the scientific development, i.e., deeper understanding of the energy transfer process from the solar wind to the coupled magnetosphere-ionosphere-thermosphere system. The purpose of this paper is to collect the most relevant results related to these topics obtained during the COST Action ES0803. In an end-to-end forecasting scheme that uses an artificial neural network, we show that the forecasting results improve when gathering certain parameters, such as X-ray solar flares, Type II and/or Type IV radio emission and solar energetic particles enhancements as inputs for the algorithm. Regarding the solar wind-magnetosphere-ionosphere interaction topic, the geomagnetic responses at high and low latitudes are considered separately. At low latitudes, we present new insights into temporal evolution of the ring current, as seen by Burton’s equation, in both main and recovery phases of the storm. At high latitudes, the PCC index appears as an achievement in modelling the coupling between the upper atmosphere and the solar wind, with a great potential for forecasting purposes. We also address the important role of small-scale field-aligned currents in Joule heating of the ionosphere even under non-disturbed conditions. Our scientific results in the framework of the COST Action ES0803 cover the topics from the short-term solar-activity evolution, i.e., space weather, to the long-term evolution of relevant solar/heliospheric/magnetospheric parameters, i.e., space climate. On the timescales of the Hale and Gleissberg cycles (22- and 88-year cycle respectively) we can highlight that the trend of solar, heliospheric and geomagnetic parameters shows the solar origin of the widely discussed increase in geomagnetic activity in the last century.

Study of large geomagnetic storms (GMSs) and their association with different solar source activities observed during solar cycle 23

Geomagnetic storms (GMSs) are stimulated by higher solar wind flow speed (VSW) and by a southward-directed interplanetary magnetic field (IMF Bz). Two kinds of flows dominate the large scale structure of solar wind: corotating flows and transient disturbances. Corotating flows are associated with spatial variability in coronal expansion and solar rotation, whereas transient disturbances are associated with episodic ejections of material into interplanetary space from coronal regions. The high speed streams originated from coronal interaction regions (CIRs) and transient disturbances are mostly caused by fast coronal mass ejections (CMEs). CMEs are the crucial link between solar activity and transient interplanetary disturbances and are responsible for major GMSs. CMEs eject magnetic flux into interplanetary space that produces abrupt increase in the northward component of Earth's magnetic field. There are two types of geomagnetic field variations termed as long-time variation and storm-time variations. The long-term variations are very useful to solar cyclical study of geomagnetic field variation as well as change in polarity of the Sun, climate change, plants growth rate and geological change of Earth's pole. The storm time variations also known as geomagnetic storm deals the various characteristics of GMSs and their connection with solar source activities and interplanetary magnetic fields. These variations are directly affect us and shows adverse effect in satellites, communication system and power losses. In the present study, we have analysed large geomagnetic storms (GMSs) associated with storm time index (D st ) decrease of more than 100 nT observed during solar cycle 23

Directional sensitivity of MuSTAnG muon telescope

We investigate directional sensitivity of MuSTAnG muon telescope by deriving the distribution of secondary muons, which create the counting rate of telescope, by asymptotic directions of primary protons. This distribution, defined as “directivity function”, allows us to clarify protons appearing from which direction essentially contribute to counting rate of detector. Directivity function has different behavior for the muons falling on the telescope at different zenith and polar angles. Vertical, West, and East fluxes exhibit strong maximums near the asymptotic longitude about 61°, whereas North and South fluxes have larger spread distributions. About 65% of muons, which create the Vertical counting rate of MuSTAnG, are produced by the primary protons, coming in the interval of asymptotic longitudes about (50°, 80°). Using directivity function will allow one to more correctly determine the location of interplanetary disturbances. Analogous analysis, made for other muon detectors, will clarify their directional sensitivities, improving by this the forecasting capability of network of ground-based muon detectors.

Multispacecraft observations of the terrestrial bow shock and magnetopause during extreme solar wind disturbances

Abstract. Three events are discussed from the declining phase of the last solar cycle when the magnetopause and/or the bow shock were observed unusually close to the Earth due to major interplanetary disturbances. The observed extreme locations of the discontinuities are compared with the predictions of three magnetopause and four bow shock models which describe them in considerably different ways using statistical methods based on observations. A new 2-D magnetopause model is introduced (based on Verigin et al., 2009) which takes into account the pressure of the compressed magnetosheath field raised by the interplanetary magnetic field (IMF) component transverse to the solar wind flow. The observed magnetopause crossings could be predicted with a reasonable accuracy (0.1–0.2 RE) by one of the presented models at least. For geosynchronous magnetopause crossings observed by the GOES satellites, (1) the new model provided the best predictions when the IMF was extremely large having a large negative Bz component, and (2) the predictions of the model of Shue et al. (1998) agreed best with the observations when the solar wind dynamic pressure was extremely large. The magnetopause crossings close to the cusp observed by the Cluster spacecraft were best predicted by the 3-D model of Lin et al. (2010). The applied empirical bow shock models and the 3-D semi-empiric bow shock model combined with magnetohydrodynamic (MHD) solution proved to be insufficient for predicting the observed unusual bow shock locations during large interplanetary disturbances. The results of a global 3-D MHD model were in good agreement with the Cluster observations on 17 January 2005, but they did not predict the bow shock crossings on 31 October 2003.

VARIATIONS OF THE MUON FLUX AT SEA LEVEL ASSOCIATED WITH INTERPLANETARY ICMEs AND COROTATING INTERACTION REGIONS

We present the results of an ongoing survey on the association between the muon flux variation at ground level (3 m above sea level) registered by the Tupi telescopes (Niteri-Brazil, 229S, 432W, 3 m) and the Earth-directed transient disturbances in the interplanetary medium propagating from the Sun (such as coronal mass ejections (CME), and corotating interaction regions (CIRs)). Their location inside the South Atlantic Anomaly region enables the muon telescopes to achieve a low rigidity of response to primary and secondary charged particles. The present study is primarily based on experimental events obtained by the Tupi telescopes in the period from 2010 August to 2011 December. This time period corresponds to the rising phase of solar cycle 24. The Tupi events are studied in correlation with data obtained by space-borne detectors (SOHO, ACE, GOES). Identification of interplanetary structures and associated solar activity was based on the nomenclature and definitions given by the satellite observations, including an incomplete list of possible interplanetary shocks observed by the CELIAS/MTOF Proton Monitor on the Solar and Heliospheric Observatory (SOHO) spacecraft. Among 29 experimental events reported in the present analysis, there are 15 possibly associated with the CMEs and sheaths, and 3 events with the CIRs (forward or reverse shocks); the origin of the remaining 11 events has not been determined by the satellite detectors. We compare the observed time (delayed or anticipated) of the muon excess (positive or negative) signal on Earth (the Tupi telescopes) with the trigger time of the interplanetary disturbances registered by the satellites located at Lagrange point L1 (SOHO and ACE). The temporal correlation of the observed ground-based events with solar transient events detected by spacecraft suggests a real physical connection between them. We found that the majority of observed events detected by the Tupi experiment were delayed in relation to the satellite triggers. This result agrees with theoretical expectations. Our experimental data indicate that the Tupi experiment is able to add new information and can be complementary to other techniques designed to interpret the origin of some interplanetary disturbances observed by satellites.

Forbush effects with a sudden and gradual onset

For a comprehensive study of the Forbush effects and their relation to solar and geomagnetic activity, a database of transient phenomena in cosmic rays and the interplanetary medium has been created, which is continuously updated with data on new events. Based on these data, we study the dependence of the Forbush effects on various internal and external parameters, as well as select different groups of events. In this paper, we consider recurrent (caused by high-speed solar wind streams from coronal holes) and sporadic (associated with coronal mass ejections) events. We investigate groups of events with a sudden and gradual onset. We show that the resulting dependencies of the Forbush effects (on the parameters of interplanetary disturbances, geomagnetic activity indices, etc.) are substantially different for the above-mentioned groups. Most likely, these differences are caused by different sources of solar wind disturbances.

Near 13.5-day periodicity in Muon Detector data during late 2001 and early 2002

In this study we perform a continuous Morlet wavelet transform method in time series of secondary cosmic rays and 1AU interplanetary medium parameters for the interval from October 2001 to October 2002. The near 13.5-day periodicity was obtained during late 2001, and it was remarkable for muon data. Even though some works have pointed out that the main activations of the 13.5day recurrence in near-Earth solar wind are related, e.g., with the heliosheet crossings or to the occurrence at 1AU of two high speed streams approximately 180° apart in solar longitude per solar rotation, we aim to show that the period of about half the solar rotation during the end months of 2001 present in muon time series was apparently due to the occurrence of non-recurrent interplanetary disturbances. The interconnections among successive Forbush decreases, recovery phases and gradual muon depressions (associated with corotating interaction regions) seem to play an important role in such 13.5-day periodicity.

Forecasting of low‐latitude storm‐time ionospheric foF2 using support vector machine

An empirical model for predicting low‐latitude storm‐time ionospheric foF2 is developed using the support vector machine technique. Considering that the ionospheric disturbances are mainly caused by interplanetary disturbances, the solar wind data are introduced as model input, as well as the ionospheric observations of Haikou (HK, with geographic coordinates of 110.3°E and 20.0°N, and geomagnetic latitudes of 8.6°N) and Chongqing (CQ, 106.5°E, 29.6°N, and geomagnetic latitudes of 18.1°N) in China. Data from 45 storms are selected as training samples to construct the model, and other 26 storms are used to validate and evaluate the model. The results indicate that the model proposed here can capture the low‐latitude ionospheric disturbances most of the time. Compared with another empirical model, STORM, which has been included in International Reference Ionosphere (IRI) as storm time corrections, our model shows remarkable improvement at least for the given events.

Precursor Effects in Different Cases of Forbush Decreases

Over the last few years, the pre-decreases or pre-increases of the cosmic-ray intensity observed before a Forbush decrease, called the precursor effect and registered by the worldwide neutron monitor network, have been investigated for different cases of intense events. The Forbush decreases presented in this particular study were chosen from a list of events that occurred in the time period 1967 – 2006 and were characterized by an enhanced first harmonic of cosmic-ray anisotropy prior to the interplanetary disturbance arrival. The asymptotic longitudinal cosmic-ray distribution diagrams for the events under consideration were studied using the “Ring of Stations” method, and data on solar flares, solar-wind speed, geomagnetic indices, and interplanetary magnetic field were analyzed in detail. The results revealed that the use of this method allowed the selection of a large number of events with well-defined precursors, which could be separated into at least three categories, according to duration and longitudinal zone. Finally, this analysis showed that the first harmonic of cosmic-ray anisotropy could serve as an adequate tool in the search for precursors and could also be evidence for them.

Erratum to: “Dependence of Forbush-Decrease Magnitudes on Parameters of Solar Eruptions”

By data of the 23rd solar cycle, it is shown that close statistical relations exist between quantitative parameters of dimmings and arcades caused by solar coronal mass ejections (CMEs), on the one hand, and magnitudes of non-recurrent Forbush-decreases of the galactic cosmic ray flux, as well as the propagation time of disturbances from the Sun to the Earth, on the other hand. Parameters of dimmings and arcades, in particular their summarized magnetic flux of the prolonged field at the photospheric level, were calculated by data of the EUV SOHO/EIT telescope in the 195 A Received results mean that the scale, characteristics, and propagation time of interplanetary disturbances to the Earth are determined to a large degree by measurable parameters of solar eruptions and may be estimated in advance by observations of dimmings and arcades in the EUV range.

Industry and Government Space Weather Experts Meet

The fifth annual NOAA Space Weather Prediction Center (SWPC)-Commercial Space Weather Interest Group (CSWIG) Summit was held on 28 April 2011 in Boulder, Colo., in association with the 2011 Space Weather Workshop. Interest was high, in the United States and internationally, in potential space weather impacts on many aspects of everyday life because of the increased vulnerability of technological systems and the possibility that a major space weather event may occur as the twenty-fourth solar cycle begins to progress toward solar maximum. Industry and government space weather experts participated in the summit. Devrie Intriligator (Carmel Research Center, Inc.) and W. Kent Tobiska (Space Environment Technologies (SET)) served as cochairs. Tom Bogdan, Director of SWPC, summarized SWPC’s current fiscal situation and future plans. SWPC has been successful in educating members of the executive branch and other government officials about space weather. President Obama’s proposed fiscal year (FY) 2012 budget includes Department of Defense and NOAA funding for the Deep Space Climate Observatory (DSCOVR), the replacement for the Advanced Composition Explorer (ACE) spacecraft, which warns of approaching interplanetary disturbances from the Sun. It is crucial for Congress to appropriate this funding if DSCOVR is to be launched on schedule in 2014. The Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC-2) mission is also in the proposed FY 2012 budget. Starting in early fall 2011, SWPC is planning to have two forecasters on duty 24 hours a day, 7 days a week. SWPC’s top operational priorities include an improved WangSheeleyArge (WSA) model of the Sun/solar wind interface and a Ground Induced Current regional model. A high priority is improved forecasting of the interplanetary magnetic field characteristics of a coronal mass ejection that hits Earth. David Bouwer (SET) summarized SWPC’s External Space Weather Data Store (E-SWDS) and other data/model sources. E-SWDS is the most reliable data source with the fewest changes/interruptions in service, format, and parameters. CSWIG looks forward to when E-SWDS also will include improved model outputs (e.g., ENLIL, WSA, etc.). Intriligator summarized concerns on the quality and quantity of future data including those from ACE and National Polar-Orbiting Operational Environmental Satellite System (NPOESS) replacements, the Geostationary Operational Environmental Satellite (GOES), etc. Space weather research, operations, and forecasts are data limited, and longterm monitoring of solar, interplanetary, and near-Earth regions is crucial. NOAA is tasked with this monitoring. Stable funding of long-term spacecraft lines (e.g., GOES) is needed. Michael Bonadonna (Office of the Federal Coordinator for Meteorology (OFCM)) updated the group on the National Space Weather Program (NSWP) and OFCM activities. One of the near-term priorities of OFCM is to improve its ability to work with the commercial sector. At present, there is no mechanism for the commercial sector to participate in the NSWP Council or other high-level NSWP activities. The Office of Science and Technology Policy has requested that NSWP assess U.S. space weather capabilities now and 10 years in the future. Tobiska discussed CSWIG participation in software test beds and Small Business Innovative Research opportunities as ways of leveraging funding. He also discussed moving toward space weather common practices and a quality assurance program including standards as developed by the American Institute of Aeronautics and Astronautics (http://spacewx.com, see the “Standards” link under “Resources”). Geoff Crowley (Atmospheric and Space Technology Research Associates) reported on the American Commercial Space Weather Association (ACSWA), the space weather association that was unanimously formed last year at the SWPCCSWIG Summit. The ACSWA executive committee (Crowley, Intriligator, Robert Schunk, and Tobiska) had earlier drafted the mission statement for ACSWA and established a Web site (http://sw01.spaceweather.usu.edu/ACSWA/ landing.html), which was unveiled at the summit meeting. Bonadonna and Bogdan enthusiastically supported ACSWA. Genene Fisher

MHD structure of interplanetary disturbances observed near the earth during the solar-terrestrial storm of November 7–13, 2004

This paper considers the MHD structure and configuration of near-Earth interplanetary disturbances during the heliospheric extrastorm of November 2004, taking into account the effect of the IMF sector structure and using the measurements of near-Earth satellites. During three successive disturbance intervals, the Earth entered, remained and left a relative narrow positive sector with flare-active region 10696, which generated a series of shocks and an active transequatorial filament. It has been indicated that the MHD structure and configuration of near-Earth disturbances substantially and specifically (for each position) depend on the IMF sector structure and interactions between shocks and sector boundaries, filaments, and magnetic clouds in these three different positions. Specifically, this manifested itself in multiple crossings of sector boundaries and considerable deformations of magnetic clouds. It has been indicated that the models of circular clouds are applied with limitations under the considered conditions.

Enhanced diurnal variation and Forbush decreases recorded with Lead-Free Gulmarg Neutron Monitor during the solar active period of late October 1989

The cosmic ray variations consequent upon the interplanetary disturbances during the solar active period of late October 1989 have been investigated by using the data recorded with the Lead-Free Gulmarg Neutron Monitor (LFGNM). Apart from recording total neutron count, it is also set to record neutron bunches with occurrence rates of 1–9 in short time intervals of 50 ms duration. Whereas the Forbush decrease (FD) profile observed in the total hourly count rate of this monitor compares well with the conventional neutron monitors, the neutron bunch-1 data reveals clear and large amplitude diurnal variation that persisted for about 10 consecutive days with average phase close to ∼ 1700 h direction. The power spectrum analysis of the neutron bunch-1 data by maximum entropy method (MEM) further revealed presence of semi- and tri-diurnal components also. The most intriguing result on anisotropic variation observed with LFGNM in a distinct mode of recording bunch-1 neutrons is unique thus far, though consistent with the strong unidirectional diurnal anisotropy observations made by conventional neutron monitors during the said period. We report the observations and the results in this work.

Forward modelling to determine the observational signatures of white-light imaging and interplanetary scintillation for the propagation of an interplanetary shock in the ecliptic plane

Recent coordinated observations of interplanetary scintillation (IPS) from the EISCAT, MERLIN, and STELab, and stereoscopic white-light imaging from the two heliospheric imagers (HIs) onboard the twin STEREO spacecraft are significant to continuously track the propagation and evolution of solar eruptions throughout interplanetary space. In order to obtain a better understanding of the observational signatures in these two remote-sensing techniques, the magnetohydrodynamics of the macro-scale interplanetary disturbance and the radio-wave scattering of the micro-scale electron-density fluctuation are coupled and investigated using a newly constructed multi-scale numerical model. This model is then applied to a case of an interplanetary shock propagation within the ecliptic plane. The shock could be nearly invisible to an HI, once entering the Thomson-scattering sphere of the HI. The asymmetry in the optical images between the western and eastern HIs suggests the shock propagation off the Sun–Earth line. Meanwhile, an IPS signal, strongly dependent on the local electron density, is insensitive to the density cavity far downstream of the shock front. When this cavity (or the shock nose) is cut through by an IPS ray-path, a single speed component at the flank (or the nose) of the shock can be recorded; when an IPS ray-path penetrates the sheath between the shock nose and this cavity, two speed components at the sheath and flank can be detected. Moreover, once a shock front touches an IPS ray-path, the derived position and speed at the irregularity source of this IPS signal, together with an assumption of a radial and constant propagation of the shock, can be used to estimate the later appearance of the shock front in the elongation of the HI field of view. The results of synthetic measurements from forward modelling are helpful in inferring the in-situ properties of coronal mass ejection from real observational data via an inverse approach.