Divya Oberoi - Academia.edu (original) (raw)
Papers by Divya Oberoi
The Astrophysical Journal
In this work, we study a class of recently discovered meter-wave solar transients referred to as ... more In this work, we study a class of recently discovered meter-wave solar transients referred to as Weak Impulsive Narrowband Quiet Sun Emission (WINQSEs). Their strength is a few percent of the quiet Sun background and is characterized by their very impulsive, narrowband, and ubiquitous presence in quiet Sun regions. Mondal et al. (2020) hypothesized that these emissions might be the radio counterparts of nanoflares, and their potential significance warrants detailed studies. Here we present an analysis of data from an extremely quiet time and with improved methodology over the previous work. As before, we detect numerous WINQSEs, which we have used for their further characterization. Their key properties, namely, their impulsive nature and ubiquitous presence in the quiet Sun, are observed in these data as well. Interestingly, we also find some of the observed properties to differ significantly from the earlier work. With this demonstration of routine detection of WINQSEs, we hope to...
<p>The perplexing mystery of what maintains the solar coronal temperature at about a millio... more <p>The perplexing mystery of what maintains the solar coronal temperature at about a million K, while the visible disc of the Sun is only at 5800 K, has been a long standing problem in solar physics. A recent study by Mondal et al. (2020, ApJ, 895, L39)  has provided the first evidence for the presence of numerous ubiquitous impulsive emissions at low radio frequencies from the quiet sun regions, which could hold the key to solving this mystery. These Weak Impulsive Narrowband Quiet Sun Emissions (WINQSEs) occur at rates of about five hundred events per minute, and their strength is only a few percent of the background steady emission. Based on earlier work with events of larger flux densities and theoretical considerations, WINQSEs are expected to be compact in the image plane. To characterise the spatial structure of WINQSEs, we have developed a pipeline based on an unsupervised machine learning approach. We first identify the boundaries of the radio sun using edge detection techniques, and detect peaks within the solar boundary. Density-Based Spatial Clustering of Application with Noise (DBSCAN), an unsupervised machine learning algorithm, is used to classify the peaks as isolated or clustered. It is also used to find the optimal hyper-parameters for peak-fitting. The peaks are then fit with Gaussian models, and statistical and heuristic filtering criteria are used to obtain robust fits for a subset of these WINQSEs . We find that the vast majority of WINQSEs can be described by well behaved compact Gaussians. By its very design, this approach is focused on morphological characterisation of these weak features and is better suited for identifying them than earlier attempts. We present here our first results of the observed distributions of intensities, sizes and axial ratios of the Gaussian models for WINQSEs arrived at from analysis of multiple independent datasets.</p>
Monthly Notices of the Royal Astronomical Society, 2012
Antenna layout is an important design consideration for radio interferometers because it determin... more Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed-even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution.
2022 3rd URSI Atlantic and Asia Pacific Radio Science Meeting (AT-AP-RASC)
Magnetic field couples the solar interior to the solar atmosphere, known as corona. Coronal magne... more Magnetic field couples the solar interior to the solar atmosphere, known as corona. Coronal magnetic field is one of the crucial parameters which determines the coronal structures and regulates the space weather phenomena like flares, coronal mass ejections, energetic particle events and solar winds (Alissandrakis & Gary, 2021; Vourlidas et al., 2020). Measuring the magnetic field at middle and higher coronal heights are extremely difficult problem and to date there is no single measurement technique available to measure the higher coronal magnetic fields routinely. polarization measurements of the low-frequency radio emissions are an ideal tool to probe the coronal magnetic fields at higher coronal heights (> 1R). Till date most of the low-frequency polarization observations of the Sun were limited to bright solar radio bursts. Here we developed a novel algorithm for performing precise polarization calibration of the solar observations done with Murchison Widefield Array, a future Square Kilometer Array (SKA) precursor. We have brought down the instrumental polarization < 1%. We anticipate this method will allow us to detect very low level polarised emissions from coronal thermal emissions, which will become a tool for routine measurements of global coronal magnetic field at higher coronal heights. This method can be easily adopted for future SKA and open a window of new discoveries using high fidelity spectro-polarimetric snapshot imaging of the Sun at low radio frequencies.
Astronomy & Astrophysics
Type II solar radio bursts are caused by magnetohydrodynamic (MHD) shocks driven by solar eruptiv... more Type II solar radio bursts are caused by magnetohydrodynamic (MHD) shocks driven by solar eruptive events such as coronal mass ejections (CMEs). Often, both fundamental and harmonic bands of type II bursts are split into sub-bands, which are generally believed to be coming from upstream and downstream regions of the shock; however, this explanation remains unconfirmed. Here, we present combined results from imaging analyses of type II radio burst band splitting and other fine structures observed by the Murchison Widefield Array (MWA) and extreme ultraviolet observations from Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) on 28 September 2014. The MWA provides imaging-spectroscopy in the range 80−300 MHz with a time resolution of 0.5 s and frequency resolution of 40 kHz. Our analysis shows that the burst was caused by a piston-driven shock with a driver speed of ∼112 km s−1 and shock speed of ∼580 km s−1. We provide rare evidence that band splitting is caused by ...
Experiments were performed with prototype antenna tiles for the Mileura Widefield Array–Low Frequ... more Experiments were performed with prototype antenna tiles for the Mileura Widefield Array–Low Frequency Demonstrator (MWA–LFD) to better understand the widefield, wideband properties of their design and to characterize the radio frequency interference (RFI) between 80 and 300 MHz at the site in Western Australia. Observations acquired during the six month deployment confirmed the predicted sensitivity of the antennas, sky-noise dominated system temperatures, and phase-coherent interferometric measurements. The radio spectrum is remarkably free of strong terrestrial signals, with the exception of two narrow frequency bands allocated to satellite downlinks and rare bursts due to ground-based transmissions being scattered from aircraft and meteor trails. Results indicate the potential of the MWA–LFD to make significant achievements in its three key science objectives: epoch of reionziation science, heliospheric science, and radio transient detection.
Journal of Astrophysics and Astronomy
To deliver the full science potential of the square kilometer array (SKA) telescope, several SKA ... more To deliver the full science potential of the square kilometer array (SKA) telescope, several SKA regional centres (SRCs) will be required to be constructed in different SKA member countries around the world. These SRCs will provide high performance compute and storage, for the generation, of advanced science data products from the basic data streams generated by the SKA science data handling and processing system, critically necessary to the success of the key science projects to be carried out by the SKA user community. They will also provide support to astronomers to enable them to carry out analysis on very large SKA datasets. Construction of such large data centre is a technical challenge for all SKA member nations. In such a situation, each country plans to construct a smaller SRC over the next few years (2022 onwards), known as a proto-SRC. In India, we propose to construct a proto-SRC, which will be used for the analysis of data from SKA pathfinders and precursors with strong Indian involvement, such as uGMRT, Meerkat and MWA. We describe our thinking on some aspects of the the storage, compute and network of the proto-SRC and how it will be used for data analysis as well as for carrying out various simulations related to SKA key science projects led by Indian astronomers. We also present our thoughts on how the proto-SRC plans to evaluate emerging hardware and software technologies and to also begin software development in areas of relevance to SKA data processing and analysis, such as algorithm implementation, pipeline development and data visualisation software.
The Astrophysical Journal
Coronal magnetic fields are well known to be one of the crucial parameters defining coronal physi... more Coronal magnetic fields are well known to be one of the crucial parameters defining coronal physics and space weather. However, measuring the global coronal magnetic fields remains challenging. The polarization properties of coronal radio emissions are sensitive to coronal magnetic fields. While they can prove to be useful probes of coronal and heliospheric magnetic fields, their usage has been limited by technical and algorithmic challenges. We present a robust algorithm for precise polarization calibration and imaging of low-radio frequency solar observations and demonstrate it on data from the Murchison Widefield Array, a Square Kilometre Array (SKA) precursor. This algorithm is based on the Measurement Equation framework, which forms the basis of all modern radio interferometric calibration and imaging. It delivers high-dynamic-range and high-fidelity full-Stokes solar radio images with instrumental polarization leakages <1%, on par with general astronomical radio imaging, an...
43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019
43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021
We present the first spectroscopic images of solar radio transients from the prototype for the Mu... more We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array (MWA), observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9-201.6 MHz. Though our observing period is characterized as a period of 'low' to 'medium' activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early
Journal of Geophysical Research: Planets, 2021
Radiometric observations of Venus have revealed a monotonic decrease of brightness temperature (T... more Radiometric observations of Venus have revealed a monotonic decrease of brightness temperature (Tb) in the decimeter wavelength regime. Such a decrease has also been independently reported by the observations using interferometric radio‐telescopes, like the Very Large Array (VLA) in the USA and the Giant Metrewave Radio Telescope (GMRT) in India. In this work, we have carried out microwave radiative transfer (RT) simulations of thermal emission from the Venusian surface at decimeter wavelengths to examine the role of subsurface properties of Venusian regolith in the continuous reduction of Tb at the microwave‐radiowave spectral domain. These simulations are compared against spectral microwave measurements by GMRT over a wide decimeter wavelength regime ranging from ∼23–128 cm. Good agreements are obtained for simulations that consider a two‐layer Venusian surface (a low‐loss medium overlaid over a reflecting/lossy medium) a situation that would arise if the subsurface layer has high dielectric properties due to the presence of semiconducting mineral assemblages such as pyrites, ferroelectric minerals, magnetite–hematite, magnetite–pyrite or magnetite–hematite–pyrite equilibrium assemblages. The thickness of the top layer, the possibilities of the formation of such layers and their geological and chemical evolutions are also discussed.
Resonance, 2021
The figure in the paper shows the measurements made using the 32 element interferometer. These el... more The figure in the paper shows the measurements made using the 32 element interferometer. These elements were parabolic dishes, each about 1.68 m in diameter. This leads to a beam size of about 25 • at the wavelength of 60 cm. They were placed in an equispaced manner along the East-West (E-W) direction, spanning a distance of about 21 m (700 ft). The details of the system, designed to provide high-resolution observations of the Sun albeit it only along one direction (E-W), originally worked at a wavelength of 21 cm are described in Christiansen and Warburton (1955, AuJPh, 6, 190). Combining the signal from these elements, gave rise to what is referred to as a fan-shaped beam along the E-W direction-an equispaced series of high-resolution beams (8.25 arcmin in the present case) separated by angular distances of about 5 •. The envelope of this family of beams is defined by the beam (directivity pattern) of individual elements of the interferometer. The separation between the adjacent beams was designed to be much larger than the angular size of the Sun, so the Sun would be seen only in one of the beams at any time.
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019
Introduction: Venus is like Earth in its size, mass and bulk density. Yet, the distinctions are m... more Introduction: Venus is like Earth in its size, mass and bulk density. Yet, the distinctions are much more pronounced, as the surface is extremely dry with a temperature of ∼750 K and pressure of ∼90 bar. The CO2 dominated atmosphere and the globally covered H2SO4 clouds make the study of its lower atmosphere and surface thermo-physical properties extremely difficult. While the satellite-based remote sensing of its lower atmosphere has been limited to single polarization, the lander-based in-situ measurements were limited to localized regions and were severely affected by the planetary conditions. The Earth-based radio telescopes using interferometry have the potential for multi-frequency and dual-polarization (H and V) observations which can be used to study the thermo-physical properties of the surface and the lower atmosphere with reasonable spatial resolutions. Scientific Problem: More than 100 observations were carried out on Venus over a wide frequency range between mm-cm wavel...
The Astrophysical Journal
In this work, we study a class of recently discovered meter-wave solar transients referred to as ... more In this work, we study a class of recently discovered meter-wave solar transients referred to as Weak Impulsive Narrowband Quiet Sun Emission (WINQSEs). Their strength is a few percent of the quiet Sun background and is characterized by their very impulsive, narrowband, and ubiquitous presence in quiet Sun regions. Mondal et al. (2020) hypothesized that these emissions might be the radio counterparts of nanoflares, and their potential significance warrants detailed studies. Here we present an analysis of data from an extremely quiet time and with improved methodology over the previous work. As before, we detect numerous WINQSEs, which we have used for their further characterization. Their key properties, namely, their impulsive nature and ubiquitous presence in the quiet Sun, are observed in these data as well. Interestingly, we also find some of the observed properties to differ significantly from the earlier work. With this demonstration of routine detection of WINQSEs, we hope to...
<p>The perplexing mystery of what maintains the solar coronal temperature at about a millio... more <p>The perplexing mystery of what maintains the solar coronal temperature at about a million K, while the visible disc of the Sun is only at 5800 K, has been a long standing problem in solar physics. A recent study by Mondal et al. (2020, ApJ, 895, L39)  has provided the first evidence for the presence of numerous ubiquitous impulsive emissions at low radio frequencies from the quiet sun regions, which could hold the key to solving this mystery. These Weak Impulsive Narrowband Quiet Sun Emissions (WINQSEs) occur at rates of about five hundred events per minute, and their strength is only a few percent of the background steady emission. Based on earlier work with events of larger flux densities and theoretical considerations, WINQSEs are expected to be compact in the image plane. To characterise the spatial structure of WINQSEs, we have developed a pipeline based on an unsupervised machine learning approach. We first identify the boundaries of the radio sun using edge detection techniques, and detect peaks within the solar boundary. Density-Based Spatial Clustering of Application with Noise (DBSCAN), an unsupervised machine learning algorithm, is used to classify the peaks as isolated or clustered. It is also used to find the optimal hyper-parameters for peak-fitting. The peaks are then fit with Gaussian models, and statistical and heuristic filtering criteria are used to obtain robust fits for a subset of these WINQSEs . We find that the vast majority of WINQSEs can be described by well behaved compact Gaussians. By its very design, this approach is focused on morphological characterisation of these weak features and is better suited for identifying them than earlier attempts. We present here our first results of the observed distributions of intensities, sizes and axial ratios of the Gaussian models for WINQSEs arrived at from analysis of multiple independent datasets.</p>
Monthly Notices of the Royal Astronomical Society, 2012
Antenna layout is an important design consideration for radio interferometers because it determin... more Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed-even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution.
2022 3rd URSI Atlantic and Asia Pacific Radio Science Meeting (AT-AP-RASC)
Magnetic field couples the solar interior to the solar atmosphere, known as corona. Coronal magne... more Magnetic field couples the solar interior to the solar atmosphere, known as corona. Coronal magnetic field is one of the crucial parameters which determines the coronal structures and regulates the space weather phenomena like flares, coronal mass ejections, energetic particle events and solar winds (Alissandrakis & Gary, 2021; Vourlidas et al., 2020). Measuring the magnetic field at middle and higher coronal heights are extremely difficult problem and to date there is no single measurement technique available to measure the higher coronal magnetic fields routinely. polarization measurements of the low-frequency radio emissions are an ideal tool to probe the coronal magnetic fields at higher coronal heights (> 1R). Till date most of the low-frequency polarization observations of the Sun were limited to bright solar radio bursts. Here we developed a novel algorithm for performing precise polarization calibration of the solar observations done with Murchison Widefield Array, a future Square Kilometer Array (SKA) precursor. We have brought down the instrumental polarization < 1%. We anticipate this method will allow us to detect very low level polarised emissions from coronal thermal emissions, which will become a tool for routine measurements of global coronal magnetic field at higher coronal heights. This method can be easily adopted for future SKA and open a window of new discoveries using high fidelity spectro-polarimetric snapshot imaging of the Sun at low radio frequencies.
Astronomy & Astrophysics
Type II solar radio bursts are caused by magnetohydrodynamic (MHD) shocks driven by solar eruptiv... more Type II solar radio bursts are caused by magnetohydrodynamic (MHD) shocks driven by solar eruptive events such as coronal mass ejections (CMEs). Often, both fundamental and harmonic bands of type II bursts are split into sub-bands, which are generally believed to be coming from upstream and downstream regions of the shock; however, this explanation remains unconfirmed. Here, we present combined results from imaging analyses of type II radio burst band splitting and other fine structures observed by the Murchison Widefield Array (MWA) and extreme ultraviolet observations from Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) on 28 September 2014. The MWA provides imaging-spectroscopy in the range 80−300 MHz with a time resolution of 0.5 s and frequency resolution of 40 kHz. Our analysis shows that the burst was caused by a piston-driven shock with a driver speed of ∼112 km s−1 and shock speed of ∼580 km s−1. We provide rare evidence that band splitting is caused by ...
Experiments were performed with prototype antenna tiles for the Mileura Widefield Array–Low Frequ... more Experiments were performed with prototype antenna tiles for the Mileura Widefield Array–Low Frequency Demonstrator (MWA–LFD) to better understand the widefield, wideband properties of their design and to characterize the radio frequency interference (RFI) between 80 and 300 MHz at the site in Western Australia. Observations acquired during the six month deployment confirmed the predicted sensitivity of the antennas, sky-noise dominated system temperatures, and phase-coherent interferometric measurements. The radio spectrum is remarkably free of strong terrestrial signals, with the exception of two narrow frequency bands allocated to satellite downlinks and rare bursts due to ground-based transmissions being scattered from aircraft and meteor trails. Results indicate the potential of the MWA–LFD to make significant achievements in its three key science objectives: epoch of reionziation science, heliospheric science, and radio transient detection.
Journal of Astrophysics and Astronomy
To deliver the full science potential of the square kilometer array (SKA) telescope, several SKA ... more To deliver the full science potential of the square kilometer array (SKA) telescope, several SKA regional centres (SRCs) will be required to be constructed in different SKA member countries around the world. These SRCs will provide high performance compute and storage, for the generation, of advanced science data products from the basic data streams generated by the SKA science data handling and processing system, critically necessary to the success of the key science projects to be carried out by the SKA user community. They will also provide support to astronomers to enable them to carry out analysis on very large SKA datasets. Construction of such large data centre is a technical challenge for all SKA member nations. In such a situation, each country plans to construct a smaller SRC over the next few years (2022 onwards), known as a proto-SRC. In India, we propose to construct a proto-SRC, which will be used for the analysis of data from SKA pathfinders and precursors with strong Indian involvement, such as uGMRT, Meerkat and MWA. We describe our thinking on some aspects of the the storage, compute and network of the proto-SRC and how it will be used for data analysis as well as for carrying out various simulations related to SKA key science projects led by Indian astronomers. We also present our thoughts on how the proto-SRC plans to evaluate emerging hardware and software technologies and to also begin software development in areas of relevance to SKA data processing and analysis, such as algorithm implementation, pipeline development and data visualisation software.
The Astrophysical Journal
Coronal magnetic fields are well known to be one of the crucial parameters defining coronal physi... more Coronal magnetic fields are well known to be one of the crucial parameters defining coronal physics and space weather. However, measuring the global coronal magnetic fields remains challenging. The polarization properties of coronal radio emissions are sensitive to coronal magnetic fields. While they can prove to be useful probes of coronal and heliospheric magnetic fields, their usage has been limited by technical and algorithmic challenges. We present a robust algorithm for precise polarization calibration and imaging of low-radio frequency solar observations and demonstrate it on data from the Murchison Widefield Array, a Square Kilometre Array (SKA) precursor. This algorithm is based on the Measurement Equation framework, which forms the basis of all modern radio interferometric calibration and imaging. It delivers high-dynamic-range and high-fidelity full-Stokes solar radio images with instrumental polarization leakages <1%, on par with general astronomical radio imaging, an...
43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019
43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021
We present the first spectroscopic images of solar radio transients from the prototype for the Mu... more We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array (MWA), observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9-201.6 MHz. Though our observing period is characterized as a period of 'low' to 'medium' activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early
Journal of Geophysical Research: Planets, 2021
Radiometric observations of Venus have revealed a monotonic decrease of brightness temperature (T... more Radiometric observations of Venus have revealed a monotonic decrease of brightness temperature (Tb) in the decimeter wavelength regime. Such a decrease has also been independently reported by the observations using interferometric radio‐telescopes, like the Very Large Array (VLA) in the USA and the Giant Metrewave Radio Telescope (GMRT) in India. In this work, we have carried out microwave radiative transfer (RT) simulations of thermal emission from the Venusian surface at decimeter wavelengths to examine the role of subsurface properties of Venusian regolith in the continuous reduction of Tb at the microwave‐radiowave spectral domain. These simulations are compared against spectral microwave measurements by GMRT over a wide decimeter wavelength regime ranging from ∼23–128 cm. Good agreements are obtained for simulations that consider a two‐layer Venusian surface (a low‐loss medium overlaid over a reflecting/lossy medium) a situation that would arise if the subsurface layer has high dielectric properties due to the presence of semiconducting mineral assemblages such as pyrites, ferroelectric minerals, magnetite–hematite, magnetite–pyrite or magnetite–hematite–pyrite equilibrium assemblages. The thickness of the top layer, the possibilities of the formation of such layers and their geological and chemical evolutions are also discussed.
Resonance, 2021
The figure in the paper shows the measurements made using the 32 element interferometer. These el... more The figure in the paper shows the measurements made using the 32 element interferometer. These elements were parabolic dishes, each about 1.68 m in diameter. This leads to a beam size of about 25 • at the wavelength of 60 cm. They were placed in an equispaced manner along the East-West (E-W) direction, spanning a distance of about 21 m (700 ft). The details of the system, designed to provide high-resolution observations of the Sun albeit it only along one direction (E-W), originally worked at a wavelength of 21 cm are described in Christiansen and Warburton (1955, AuJPh, 6, 190). Combining the signal from these elements, gave rise to what is referred to as a fan-shaped beam along the E-W direction-an equispaced series of high-resolution beams (8.25 arcmin in the present case) separated by angular distances of about 5 •. The envelope of this family of beams is defined by the beam (directivity pattern) of individual elements of the interferometer. The separation between the adjacent beams was designed to be much larger than the angular size of the Sun, so the Sun would be seen only in one of the beams at any time.
2019 URSI Asia-Pacific Radio Science Conference (AP-RASC), 2019
Introduction: Venus is like Earth in its size, mass and bulk density. Yet, the distinctions are m... more Introduction: Venus is like Earth in its size, mass and bulk density. Yet, the distinctions are much more pronounced, as the surface is extremely dry with a temperature of ∼750 K and pressure of ∼90 bar. The CO2 dominated atmosphere and the globally covered H2SO4 clouds make the study of its lower atmosphere and surface thermo-physical properties extremely difficult. While the satellite-based remote sensing of its lower atmosphere has been limited to single polarization, the lander-based in-situ measurements were limited to localized regions and were severely affected by the planetary conditions. The Earth-based radio telescopes using interferometry have the potential for multi-frequency and dual-polarization (H and V) observations which can be used to study the thermo-physical properties of the surface and the lower atmosphere with reasonable spatial resolutions. Scientific Problem: More than 100 observations were carried out on Venus over a wide frequency range between mm-cm wavel...