Radio Echo Research Articles

Deciphering Optimal Radar Ensemble for Advancing Sleep Posture Prediction through Multiview Convolutional Neural Network (MVCNN) Approach Using Spatial Radio Echo Map (SREM).

Assessing sleep posture, a critical component in sleep tests, is crucial for understanding an individual's sleep quality and identifying potential sleep disorders. However, monitoring sleep posture has traditionally posed significant challenges due to factors such as low light conditions and obstructions like blankets. The use of radar technolsogy could be a potential solution. The objective of this study is to identify the optimal quantity and placement of radar sensors to achieve accurate sleep posture estimation. We invited 70 participants to assume nine different sleep postures under blankets of varying thicknesses. This was conducted in a setting equipped with a baseline of eight radars-three positioned at the headboard and five along the side. We proposed a novel technique for generating radar maps, Spatial Radio Echo Map (SREM), designed specifically for data fusion across multiple radars. Sleep posture estimation was conducted using a Multiview Convolutional Neural Network (MVCNN), which serves as the overarching framework for the comparative evaluation of various deep feature extractors, including ResNet-50, EfficientNet-50, DenseNet-121, PHResNet-50, Attention-50, and Swin Transformer. Among these, DenseNet-121 achieved the highest accuracy, scoring 0.534 and 0.804 for nine-class coarse- and four-class fine-grained classification, respectively. This led to further analysis on the optimal ensemble of radars. For the radars positioned at the head, a single left-located radar proved both essential and sufficient, achieving an accuracy of 0.809. When only one central head radar was used, omitting the central side radar and retaining only the three upper-body radars resulted in accuracies of 0.779 and 0.753, respectively. This study established the foundation for determining the optimal sensor configuration in this application, while also exploring the trade-offs between accuracy and the use of fewer sensors.

Convective Phenomenes in the Context of Meso-β-scale Convective Structures

This review article presents the results of radar studies of convective phenomena in Moldavia and the North Caucasus using Eulerian (ECS) and Lagrangian (LCS) coordinate systems. Application of the Lagrangian approach allowed us to exclude the influence of the tropospheric displacement and to obtain integral grid patterns of thunderstorm-hail processes. These structures are especially well manifested at small wind shears (up to 1 m/sec/km). At large shears, the mesh structures are transformed predominantly into linear structures. The methodology for obtaining integral pictures of radio echoes of thunderstorm processes is described. Intersections of linear elements, which we call faces, occur at nodes. The latter plays a particularly important role in the dynamics and kinematics of convective storms. The latter play a particularly important role in the dynamics and kinematics of convective storms. The development of storms occurs along the facets and at the nodes of meso-β-scale convective structures (MMCS), which explains the mechanisms of splitting and merging of storms: in the first case the facets diverge, in the second case they converge. The relations of motion vectors for different types of storms are obtained. It is shown that the direction of the radio echo canopy coincides with the storm motion trajectory; the evolution vector (propagation) for the most powerful storms deviates from the storm displacement direction by 80°–135°. The structure of the updated band within which the Flanking Line is formed for supercells and multicells is studied. Mnemonic rules have been derived that allow one to infer from instantaneous patterns of anvil orientation and the mutual location of storms whether they are converging or diverging, and to identify left- or right-moving storms. A hypothesis on the internal structure of the cold front of the 2nd kind is stated. The main conclusion of the work is that the evolution of storms is determined by the configuration of meso-β-scale convective structures. This explains various convective phenomena from unified positions. The results are applicable in works on modification of convective cloudiness, for ultra-short-term forecasts of dangerous phenomena, storm warnings of the population, rescue services, etc.

Editorial for the Special Issue “Review of Application Areas of GPR”

Ground-penetrating radar (GPR) started as a radio echo sounding technology during the second half of the last century, but it is now a well-established and widely adopted technology for producing high-resolution images of subsurface [...]

Bistatic Radar Tomography of Shear Margins: Simulated Temperature and Basal Material Inversions

A significant portion of the sea level contributions of Antarctica and Greenland comes from ice streams, but the physical processes controlling ice stream width are poorly understood, especially when topographic controls are absent. Recent modeling studies have indicated that ice stream width may be controlled by elevated temperatures inside ice stream shear margins. While radio echo sounders can provide measurements of englacial water storage and subglacial conditions, existing radar-sounding techniques cannot measure temperature profiles at the scale required to test this hypothesis. We propose using a wide-angle radar survey and tomographic inversion to resolve temperature profiles, gradients, and anomalies at the scale required to study the thermophysical controls on shear margins. Recent work produced a bistatic radar system capable of obtaining the long offsets required for well-constrained inversions; however, shear-margin-specific temperature inversion techniques have not been developed for this system. In this article, we develop Newton’s method and alternating direction method of multipliers’ inversions for estimating temperature distribution and basal material across ice stream shear margins. We evaluate the performance of these inversion techniques on simulated bistatic radar-sounding data. Our results suggest that bistatic radar tomography experiments should be able to produce temperature maps on 50 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times50$ </tex-math></inline-formula> m grids with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.83~^{\circ} \text{C}~\pm ~0.084~^{\circ} \text{C}$ </tex-math></inline-formula> mean temperature error, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.58~^{\circ} \text{C}~\pm ~0.20~^{\circ} \text{C}$ </tex-math></inline-formula> maximum temperature error, and an error in relative basal permittivity of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.63~\pm ~0.08$ </tex-math></inline-formula> for a 4-km transect.

An overview of GPR subsurface exploration of planets and moons

Geophysical techniques were first tested beyond Earth during the Apollo program. Of those examined, radio-wave propagation methods appeared to be the most suitable for the moon and other solar system bodies. This was due to the electromagnetic characteristics of planetary subsurfaces and the possibility to remotely perform measurements on board spacecrafts and rovers. After the first successful experiment on the moon, more than 20 years passed before ground-penetrating radar (GPR) was included in the payload of a planetary mission. Technological advancements in GPR design and successful results of radio echo sounding measurements for the detection of basal water below terrestrial ice sheets paved the way for the application of similar techniques to search for liquid water in the Martian subsurface. Since deployment of the first two subsurface radar sounders above Mars, the number of proposed planetary missions relying on GPR for surveying the subsurface of planets, moons, and other objects has grown progressively. Six orbiting radar sounders and five GPRs mounted on rovers/landers have been employed so far to explore the moon, Mars, and comet 67P/GC. Some of these are in full operation and some are just starting to operate. Planned missions to the icy moons of Jupiter will also depend heavily on radar sounders to detect evidence of an internal ocean on Europa and to understand the habitability conditions on Europa, Ganymede, and Callisto. Finally, planetary missions to Earth's twin, the planet Venus, could take advantage of GPR to understand the cause of its drastic change in climatic conditions and the geologic phenomena that contributed to changing a watery and hospitable surface into a hot and asphyxiating inhabitable planet.

Basal melt of the southern Filchner Ice Shelf, Antarctica

Abstract. Basal melt of ice shelves is a key factor governing discharge of ice from the Antarctic Ice Sheet as a result of its effects on buttressing. Here, we use radio echo sounding to determine the spatial variability of the basal melt rate of the southern Filchner Ice Shelf, Antarctica, along the inflow of Support Force Glacier. We find moderate melt rates with a maximum of 1.13 m a−1 about 50 km downstream of the grounding line. The variability of the melt rates over distances of a few kilometres is low (all but one &lt; 0.15 m a−1 at &lt; 2 km distance), indicating that measurements on coarse observational grids are able to yield a representative melt rate distribution. A comparison with remote-sensing-based melt rates revealed that, for the study area, large differences were due to inaccuracies in the estimation of vertical strain rates from remote sensing velocity fields. These inaccuracies can be overcome by using modern velocity fields.

Post-Processing Synchronized Bistatic Radar for Long Offset Glacier Sounding

Radar tomography of glaciers promises to improve imaging and estimates of subsurface ice-sheet structures and properties, including temperature distributions, basal materials, ice fabric, and englacial water content. However, bistatic radar data with long (i.e., larger than the ice thickness) walk-away surveys are required to constrain high-fidelity tomographic inversions. These long-offset data have proven difficult to collect due to the hardware complexity of existing synchronization techniques. Therefore, we remove the hardware complexity required for real-time synchronization by synchronizing in postprocessing. Our technique transforms an Autonomous phase-sensitive Radio Echo Sounder (ApRES) system and a software-defined radio receiver into a coherent bistatic radar capable of recovering basal echoes at long offsets. We validated our system at Whillans Ice Stream, West Antarctica, with a walk-away survey up to 1300 m (797 m thick) and at Store Glacier, Greenland, up to 1450 m (1028 m thick). At both field sites, we measured the basal echo at angles beyond the point of total internal reflection (TIR), whose previous literature had set as a hard physical limit. We support our experimental results with high-frequency structure simulation, which shows that ground-based radar systems capture evanescent waves and are not hindered by TIR. Our analysis and experiments demonstrate a system capable of executing wide-angle bistatic radar surveys for improved geometric and radiometric resolution of inversions for englacial and subglacial properties.

Validation for Ice Flow Velocity Variations of Shirase Glacier Derived From PALSAR-2 Offset Tracking

We have shown that the flow velocity of Shirase Glacier can be estimated by applying the offset tracking method to the amplitude images derived from the phased array type L-band synthetic aperture radar type-2 (PALSAR-2) onboard the Advanced Land Observing Satellite-2. Although the offset tracking is widely used, the method is sometimes not applicable effectively and the reason is not always clear. Here, we consider a possibility of ionospheric contamination and show the validation results of the estimated flow velocity applied the offset tracking method to the PALSAR-2 data, based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> measurement of the flow velocity from the GNSS receiver on the autonomous phase-sensitive radio echo sounder simultaneously with the PALSAR-2 observation. As a result, the ionospheric contamination can yield a spurious error of ±0.2 km a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . After statistically removing the erroneous pairs, the RMSE was 0.049 km a <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> derived from the flow velocity error between the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> measurement results and estimated from satellite, and the estimated flow velocity obtained using PALSAR-2 data is proved to be in good agreement with the ground truth. Obtained spatial and temporal variations reveal signature of glacier dynamics, which prove the efficacy of the offset tracking method. The obtained ice-flow velocity increases rapidly from the upstream region to the coast, but its velocity is roughly constant over a region, 10-km long about the grounding line (GL), then gradually tends to increase again downstream from the GL. This trend has continued largely unchanged over24 years since 1996.

On the influence of glaciogenic seeding on the radar characteristics of hail clouds

40 hail and hail-hazardous clouds of various strengths were considered, which were seeded with the help of a glaciogenic agents in order to prevent and interrupt hail. An unseeded control cloud was matched for each seeded cloud. For this, the parameter dV35 was used – the volume of the radio echo of the cloud with a reflectivity of more than 35 dBZ above the level of zero isotherm. A cloud was considered to be a control cloud if at the time of the beginning of seeding and 10 minutes before that dV35 differs by no more than 15% from the same value of the seeded cloud. To assess the possible impact of seeding, the radar characteristics of pairs of seeded and control clouds were analyzed. It was found that in the seeded clouds the average, maximum and minimum values of the maximum reflectivity, the height of the upper boundary, the vertically integrated water content, the intensity of precipitation and dV35 are higher, and the height of the maximum reflectivity is slightly lower than the similar values of the control clouds.

AN AUTOMATIC EXTRACTION METHOD FOR ANTARCTIC SUBGLACIAL LAKE BASED ON RADIO ECHO SOUNDING DATA

Abstract. Detection of subglacial lakes and interpretation their hydrological connectivity is of great importance to understanding the mass balance of Antarctic ice sheet. Over the past five decades, a large number of Radio Echo Sounding (RES) data has been collected in Antarctica. However, the identification of subglacial lakes based on RES data mainly relies on visual interpretation due to the lack of quantitative indicators for subglacial lakes distinguishing. To solve this problem, an automatic subglacial lakes detection method based on the reflective characteristics of B-scan echogram is proposed in this paper. Firstly, the echo strength of the original radar echogram is corrected for the dielectric attenuation and geometric spreading in the ice. Secondly, the original radar echogram is binarized to preserve the bright subglacial lake region, and the thickness of bright pixels is measured along the direction of A-scan. Thirdly, the thickness, the variance of the thickness in the neighbourhood and the corrected echo strength are used to obtain the response value for the subglacial lake. Finally, a threshold for the response value is determined to detect subglacial lakes. It is found that the proposed method can determine the location of the subglacial lake in Antarctica's Gamburtsev Province (AGAP) region with high accuracy.

Formation of initial projection data in reflection tomography in the implementation of technical vision

The known principles of active monostatic radar are based on the effect of radio wave scattering on objects located on the path of the probing signal, and the subsequent registration of a part of the wave reflected in the direction of the emitter. However, within the framework of this study, it is of interest to register objects that do not return a reflected radio echo towards the emitter. When fixing the position of an object, it is assumed that there is a possible absence of an echo signal characteristic of classical active radar with a passive response. The absence of a characteristic echo signal does not exclude its return as a result of repeated reflection inside the scene, including along other routes and from other objects. Purpose – within the framework of the implementation of technical vision in the course of tomographic observation of a complex radar scene that solves the problems of multidimensional reconstruction, a stochastic model based on the principles of tomography describing the subject area of a complex radar scene is developed. In the indicated relevance of the development of methods for radar detection of hidden objects inaccessible for registration by classical methods, a variant of using tomographic observation of a complex radar scene is proposed. In connection with the admitted lowangle and the emerging problems of an unambiguous deterministic definition, a description of the subject area of the scene from a stochastic position is proposed. In the proposed tomographic method, in conditions of limited initial data, when a deterministic approach to the reconstruction of the radar scene is not possible, an acceptable solution is sought in the stochastic description. At a given value by sampling the space, determined by the hexagonal lattice cell, the scene reconstruction is carried out by selecting and analyzing the echo signal trajectories from the possible set of proposed ones. The decision on the choice of one or another proposed trajectory and its transfer to the category of a possible solution is carried out on the basis of a preliminary calculation of the characteristics of the stochastic description.

Design and application of the multi‐transmitting and multi‐receiving ionospheric detection network

To observe a large area of ionosphere with relatively dense observing points, we design and implement an experimental multi-transmitting and multi-receiving ionospheric detection network in China. Two transmitters located in Wuhan and Mile and two receivers located in Kaiyuan and Luxi are used to form the ionospheric detection network. The radio echoes of the network are reflected at the mid-point ionosphere between the transmitter and receiver. The radio systems in the network work simultaneously and the echoes from the two transmitters can be recorded in one ionogram of a receiver. With the inversion technique, the oblique-incidence ionogram is converted to a vertical-incidence ionogram, and then the ionospheric parameters, such as the critical frequency and peak height of F2-layer (foF2 and hmF2), as well as the electron density profile, can be obtained. The foF2 variation recorded by the oblique-incidence ionograms is compared with the same data of the vertical-incidence ionosondes in Qujing and Chongqing. There is a little deviation between the observation results of the two kinds of the ionospheric detection systems. The preliminary experimental results show that the ionospheric oblique-incidence detection network composed of several independent high-frequency transmitters and receivers is an effective and low-cost solution for large-area ionospheric observation.

Radio Echo in the Turbulent Corona and Simulations of Solar Drift-pair Radio Bursts

Abstract Drift-pair bursts are an unusual type of solar low-frequency radio emission, which appear in the dynamic spectra as two parallel drifting bright stripes separated in time. Recent imaging spectroscopy observations allowed for the quantitative characterization of the drifting pairs in terms of source size, position, and evolution. Here, the drift-pair parameters are qualitatively analyzed and compared with the newly developed Monte Carlo ray-tracing technique simulating radio-wave propagation in the inhomogeneous anisotropic turbulent solar corona. The results suggest that drift-pair bursts can be formed due to a combination of refraction and scattering processes, with the trailing component being the result of turbulent reflection (turbulent radio echo). The formation of drift-pair bursts requires an anisotropic scattering with the level of plasma density fluctuations comparable to that in type III bursts, but with a stronger anisotropy at the inner turbulence scale. The anisotropic radio-wave scattering model can quantitatively reproduce the key properties of drift-pair bursts: the apparent source size and its increase with time at a given frequency, the parallel motion of the source centroid positions, and the delay between the burst components. The trailing component is found to be virtually cospatial and following the main component. The simulations suggest that drift-pair bursts are likely to be observed closer to the disk center and below 100 MHz due to the effects of free–free absorption and scattering. The exciter of drift pairs is consistent with propagating packets of whistlers, allowing for a fascinating way to diagnose the plasma turbulence and the radio emission mechanism.

‘An Old Hullo Out of the Dark’: Radio Echoes between Samuel Beckett and Harold Pinter

Radio provided Samuel Beckett and Harold Pinter with new ways of experimenting with voice, silence, and absence. As they maximised radio’s potential to explore the ephemerality of language and non-linear narratives, the works they created were concerned with the medium itself. On radio, Beckett’s silences and Pinter’s pauses create a heightened sense of uncertainty and ambiguity. Their medium-conscious works also provided them with a platform through which they could experiment with their shared frustration with the inaccuracies of language. The article explores Pinter’s interest in Beckett’s work by drawing on Pinter’s letters to Richard Seaver, Patrick Magee, and Mick Goldstein from the Harold Pinter Archive. It then shows how Pinter’s own work is intermedial in its experimentation with new technologies such as radio. By pointing to examples within Pinter’s Landscape (1968) that speak to moments in Beckett’s Embers (1959), the parallels between these writers in their use of radio are identified. Finally, the article suggests that Pinter’s work is not merely derivative of Beckett’s but demonstrates how the radio drama of both writers is underwritten by an intermedial creative process.

Bed topography and subglacial landforms in the onset region of the Northeast Greenland Ice Stream

AbstractThe Northeast Greenland Ice Stream (NEGIS) is an important dynamic component for the total mass balance of the Greenland ice sheet, as it reaches up to the central divide and drains 12% of the ice sheet. The geometric boundary conditions and in particular the nature of the subglacial bed of the NEGIS are essential to understand its ice flow dynamics. We present a record of more than 8000 km of radar survey lines of multi-channel, ultra-wideband radio echo sounding data covering an area of 24 000 km2, centered on the drill site for the East Greenland Ice-core Project (EGRIP), in the upper part of the NEGIS catchment. Our data yield a new detailed model of ice-thickness distribution and basal topography in the region. The enhanced resolution of our bed topography model shows features which we interpret to be caused by erosional activity, potentially over several glacial–interglacial cycles. Off-nadir reflections from the ice–bed interface in the center of the ice stream indicate a streamlined bed with elongated subglacial landforms. Our new bed topography model will help to improve the basal boundary conditions of NEGIS prescribed for ice flow models and thus foster an improved understanding of the ice-dynamic setting.

Multiangle, Frequency, and Polarization Radar Measurement of Ice Sheets

Radio echo sounding of polar ice sheets provides important information on the ice bed topography and internal layers. These data have been used by scientists to create 3-D maps of polar ice sheets for climate modeling as well as to reconstruct the climate history that dates back to hundreds of thousands of years. In this article, we present the design and development of three surface-based multichannel radars in the VHF and UHF bands. We provide results from radar data multifrequency and polarization radar data collected over the Greenland ice sheet. All the three radars shared the same digital waveform generator and digitizer, and were installed in and operated on a tracked vehicle. The radars are operated with three different antenna arrays designed for operation over 170–230, 180–340, and 600–900 MHz. The results we obtained sounded more than 2.7 km thick ice with radars operating at frequencies as high as 850 MHz with more than 40 dB signal-to-noise ratio.

Some features of the day-to-day MLT wind variability in winter 2017–2018 as seen with a European/Siberian meteor radar network

We present results of wind measurements near the mesopause carried out with meteor radars (MRs) at Collm (51°N, 13°E), Obninsk (55°N, 37°E), Kazan (56°N, 49°E), Angarsk (52°N, 104°E) and Anadyr (65°N, 178°E) from October 1, 2017 till March 31, 2018. The Collm and Kazan MRs are SKiYMET radars with vertical transmission and radio echo height finding, while the other radars operate with horizontal transmission and without height finding. We paid particular attention to the meridional wind variability with periods of 4–6 days and 9–11 days. The waves with these periods are seen as spots of the wave activity in the wavelet spectra and include oscillations with different periods and different discrete zonal wavenumbers. These wave packets successively propagate as a group of waves from one site to another one in such a way that they are observed at one site and almost disappear at the previous one. The 4–6 wave group includes planetary-scale oscillations (individual spectral components) which have eastward phase velocities and mostly zonal wavenumbers 2 and 3, and the vertical wavelength exceeds 70 km at middle latitudes. The source of the oscillations is the polar jet instability. The wave group itself propagates westward, and the amplitudes of wind oscillations are approximately 5–6 m/s as obtained from the wind data averaged over the meteor zone. The 9–11 day wave set propagates westward as a group and mainly consists of spectral components which have westward phase velocity and zonal wavenumber 1. Amplitudes of these wind perturbations strongly vary from station to station and can reach, approximately, 8 m/s. The vertical wavenumber is 0.014 km−1 as taken from the Kazan and 0.05 km−1 according to the Collm data. We obtained a global view on the waves by using the AURA MLS geopotential data. We found a good correspondence between wave features obtained from the MR wind measurements and the MLS data. To our knowledge, such a wave propagation of planetary wave in the mesosphere/lower thermosphere (MLT) region has so far not obtained much attention.

Rocket investigation of electrical characteristics of the thunderstorm clouds

The description of the equipment used according to the program of rocket sensing of electrical characteristics inside thunderstorm clouds in the Caucasus, with which the profiles of the three components of the electric field intensity in the cloud were measured, taking into account the influence of electrification currents flowing on the rocket probe in the thundercloud and the electric charge accumulated on it, is given. The coordinates of the trajectory of the sounding of the thunder cloud were measured and tied to the synchronously recorded radio echo of this cloud. Much attention was paid to justifying the reliability of measurements when creating a rocket probe. The description of one experiment on rocket sounding of the thunderstorm cloud is given as an example.

Assessment of Occupational Hazards and Usage of Sea Safety Devices by Fishers of Kerala, India

ABSTRACTKerala, a maritime state on the west coast of peninsular India, constitutes approximately 10% of India’s total coastline and claims a 20% share in national marine fish production. The registered fishing fleet consists of about 29,969 motorized, 4248 mechanized, and 2515 non-motorized crafts. This study was done to assess occupational hazards faced by fishers as well as the usage of sea safety devices (SSDs) in Kerala. Information was collected from 180 mechanized, motorized, and traditional boat owners. The study revealed that capsizing, sinking, grounding, burning, collision, mishaps, man overboard, and injuries were common occupational hazards. SSDs used were life buoy, life jacket, first aid kit, emergency rations, fire extinguisher, fire bucket, global positioning system, magnetic compass, emergency position indicating radio beacon (EPIRB), sonar, echo sounder, oil lamp, signaling torch, and batteries. Fishers with mechanized boats had high knowledge and used most SSDs. Fishers with motorized boats had adequate knowledge but less SSD usage. Traditional and small-scale fishers did not use most SSDs. Non-parametric Kruskal–Wallis statistical test revealed a significant difference in regards to usage between mechanized, motorized, and traditional fishers, indicating there are gaps in usage of SSDs between the three groups of fishers. It is necessary to educate and motivate fishers with motorized and traditional boats to use SSDs.

&lt;italic&gt;In Situ&lt;/italic&gt; Demonstration of a Passive Radio Sounding Approach Using the Sun for Echo Detection

Ice sheet contributions to sea level rise present one of the greatest challenges that our society will face in the next century. However, models predicting sea level rise due to ice melt lack critical information regarding processes at the base of ice sheets. Although radio echo sounders are powerful tools that are currently used to constrain subglacial conditions, existing ice-penetrating radar systems are too resource-intensive in terms of cost, power, and logistics for multiyear deployment at a large scale. To address this, we present passive radio sounding as a low-resource approach for observing ice sheets across a range of spatial and temporal scales. While passive radar has been used for target tracking and military purposes, it has never been used for the sounding of ice sheets. Some recent work has proposed using passive radio sounding of Europa’s icy shell using Jupiter’s decametric radiation. We expand on this idea by evaluating and discussing challenges and opportunities for developing a passive radio sounder using the Sun as an illuminator of opportunity for echo detection. Here, our prototype instrument sits on the side of a cliff and measures the Sun’s direct and reflected path off the ocean surface. We then use an autocorrelation-based method to extract the amplitude and delay of the reflection. This serves as the first in situ demonstration of an autocorrelation-based passive sounder using a compact astronomical white noise signal.