A5040470180- Ionosphere and magnetosphere dynamics
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Earthquake Detection and Analysis
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Oceanographic and Atmospheric Processes
- Geophysics and Sensor Technology
- Impact of Light on Environment and Health
- GNSS positioning and interference
- Power Systems and Renewable Energy
- Atmospheric aerosols and clouds
- Plasma Diagnostics and Applications
- Climate variability and models
- Smart Grid Energy Management
- Ocean Waves and Remote Sensing
- Optical and Acousto-Optic Technologies
- Spectroscopy and Laser Applications
- Atmospheric chemistry and aerosols
- Magnetic confinement fusion research
- Radio Wave Propagation Studies
- Radiation Effects in Electronics
- Precipitation Measurement and Analysis
Laboratory for Atmospheric and Space Physics
2019-2025
University of Colorado Boulder
2019-2025
Vels University
2024
Physical Research Laboratory
2016-2020
Indian Institute of Technology Gandhinagar
2016-2018
Ravenshaw University
2011
Abstract Using NASA's Global‐scale Observations of the Limb and Disk (GOLD) imager, we report nightside ionospheric changes during G5 super geomagnetic storm 10 11 May 2024. Specifically, southern crest Equatorial Ionization Anomaly (EIA) was observed to merge with aurora near tip South America. During storm, EIA seen moving poleward as fast 450 m/s. Furthermore, extended mid‐latitudes reaching tips Africa The shift equatorial structure equatorward motion means there no mid‐latitude...
Abstract This study uses multiple ground and satellite‐based measurements to investigate the extreme ionospheric response Mother's Day storm on May 10–11, 2024. Prompt penetration electric field caused a significant enhancement in vertical drift ( 95 m/s) equatorial electrojet strength 275 nT) over Jicamarca. These eastward perturbations, along with large meridional wind, significantly altered F‐region plasma fountain at different local times. The afternoon ionization anomaly (EIA) not only...
Abstract The NASA Global‐scale Observations of the Limb and Disk (GOLD) mission has flown an ultraviolet‐imaging spectrograph on SES‐14, a communications satellite in geostationary orbit at 47.5°W longitude. That instrument observes Earth's far ultraviolet (FUV) airglow ~134–162 nm using two identical channels. observations performed include limb scans, stellar occultations, images sunlit nightside disk from 6:10 to 00:40 universal time each day. Initial analyses reveal interesting...
Following the 2022 Tonga Volcano eruption, dramatic suppression and deformation of equatorial ionization anomaly (EIA) crests occurred in American sector ∼14,000 km away from epicenter. The EIA variations associated ionosphere-thermosphere disturbances were investigated using Global Navigation Satellite System total electron content data, Global-scale Observations Limb Disk ultraviolet images, Ionospheric Connection Explorer wind ionosonde observations. main results are as follows: (a)...
Abstract The nighttime ionospheric response to a geomagnetic storm that occurred on 23–29 September 2020 is investigated over the South American, Atlantic, and West African longitude sectors using NASA's Global‐scale Observations of Limb Disk measurements. On 27 solar wind conditions were favorable for prompt penetration electric fields influence equatorial ionosphere extended longitudes. ionization anomaly (EIA) crests shifted 8°–10° poleward compared quiet time monthly mean across...
Abstract The geomagnetic storm on February 3, 2022 caused the loss of 38 Starlink satellites Space‐X. Global‐scale Observations Limb and Disk (GOLD) observations Multi‐Scale Atmosphere Geospace Environment (MAGE) model simulations are utilized to investigate thermospheric composition responses Space‐X storm. percentage difference GOLD observed O N 2 column density ratio (∑O/N ) between time (February Day‐of‐Year [DOY] 34) quiet (DOY 32) shows a depletion region in local noon sector mid‐high...
Abstract The National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb Disk (GOLD) satellite takes far‐ultraviolet images Earth from geostationary orbit. GOLD observes complete structure equatorial plasma bubbles (EPBs). Since there are repeated observations same regions Earth, zonal drift velocities EPBs derived using data. observed within 60–25°W longitudes on 27–29 November 2018 considered in present analysis. obtained 27 116 ± 4, 118 6, 105 9 m/s at North...
Abstract The Global‐scale Observations of the Limb and Disk (GOLD) is a National Aeronautics Space Administration mission opportunity designed to study how Earth's ionosphere‐thermosphere system responds geomagnetic storms, solar radiation, upward propagating atmospheric tides waves. GOLD employs two identical ultraviolet spectrographs that make observations thermosphere ionosphere from commercial communications satellite owned operated by Société Européenne des Satellites (SES) located in...
Abstract Each day the Global‐scale Observations of Limb and Disk imager observes equatorial ionization anomaly (EIA) near sunset from ∼10°E to ∼80°W geographic longitude. Most images cover ∼45° longitude (∼3 hr), most longitudes are observed multiple times. Monthly averages EIA crests' latitude (EIA lats) versus during March, September, December 2020 have been analyzed. The lats reflect combined influence winds, solar radiation, fields (electric magnetic) in region. Winter solstice differs...
Abstract A coronal mass ejection erupted from the Sun on 21 April 2023 and created a G4 geomagnetic storm 23 April. NASA's global‐scale observations of limb disk (GOLD) imager observed bright equatorial ionization anomaly (EIA) crests at ∼25° Mlat, ∼11° poleward their average locations, computed by averaging EIA during previous quiet days (18–22 April) between ∼15°W 5°W Glon. Reversed C ‐shape plasma bubbles (EPBs) were reaching ∼±36° Mlat (∼40°N ∼30°S Glat) with apex altitudes ∼4,000 km...
Abstract This paper presents coordinated and fortuitous ground‐based spaceborne observations of equatorial plasma bubbles (EPBs) over the South American area on 24 October 2018, combining following measurements: Global‐scale Observations Limb Disk far ultraviolet emission images, Global Navigation Satellite System total electron content data, Swarm in situ density observations, ionosonde virtual height drift cloud brightness temperature data. The new from Disk/ultraviolet imaging...
Abstract This study develops a new Bubble Index to quantify the intensity of 2‐D postsunset equatorial plasma bubbles (EPBs) in American/Atlantic sector, using Global‐scale Observations Limb and Disk (GOLD) nighttime data. A climatology day‐to‐day variability analysis EPBs is conducted based on newly‐derived with following results: (a) show considerable seasonal solar activity dependence, stronger (weaker) around December (June) solstice high (low) years. (b) exhibit opposite geomagnetic...
Abstract The Global‐scale Observations of Limb and Disk (GOLD) mission has provided an unusual array upper atmosphere observations from a geostationary platform, including the behavior low latitude nighttime ionosphere. One features observed by GOLD is formation X‐pattern in Equatorial Ionization Anomaly when its crests collapse near magnetic equator. This paper discusses X‐patterns that were during first 5 years (2018–2023). catalog reveals occurrences are more frequent solar activity,...
Abstract The 2022 Tongan volcanic eruption released significant energy into the atmosphere. Tropospheric satellite images show that generated pressure waves traveled globally. Global Observation of Limb and Disk (GOLD) mission observed wave‐like thermospheric temperature perturbations (>100 K) from 12 to 16 UT. These perturbations' spatial curvatures arrival times are initially similar tropospheric wave‐fronts but differ significantly with eastward propagation. had a phase speed ∼300–400...
Abstract A unique phenomenon—A geomagnetically quiet time merging of Equatorial Ionization Anomaly (EIA) crests, leading to an X‐pattern (EIA‐X) around the magnetic equator—has been observed in night‐time ionospheric measurements by Global‐scale Observations Limb and Disk mission. The pattern is also reproduced model that assimilates slant Total Electron Content from Global Navigation Satellite System Constellation Observing for Meteorology, Ionosphere, Climate 2. free‐running whole...
Abstract First results on the three‐dimensional wave characteristics in daytime upper atmosphere have been derived using measurements of oxygen dayglow emissions at 557.7, 630.0, and 777.4 nm that originate around 130, 230, 300 km (peak F region). The horizontal scale sizes gravity waves (GWs), their time periods, phase propagation angle (counterclockwise from east), speeds are found to vary range 27–227 km, 32–70 min, 207°–253°, 6–76 ms −1 , respectively. Two‐dimensional not reported...
Abstract. The diurnal variations in daytime airglow emission intensity measurements at three wavelengths OI 777.4 nm, 630.0 and 557.7 nm made from a low-latitude location, Hyderabad (17.5° N, 78.4° E; 8.9° N MLAT) India have been investigated. patterns showed both symmetric asymmetric behaviour their respective variability with respect to local noon. is not expected considering the photochemical nature of production mechanisms. reason for this observed has found be predominantly temporal...
Abstract The equatorial upper atmospheric dynamic processes show both latitudinal and longitudinal variabilities. While the variability in latitudes can exist over small distances (approximately hundreds of kilometers), behavior has been shown to be existing mainly large spatial separations thousands kilometers). In present work we have used variations thermospheric optical dayglow emissions at OI 557.7, 630.0, 777.4 nm, as tracers neutral dynamics. These are obtained simultaneously from a...
Abstract The importance of neutral wave dynamics in the understanding upper atmospheric processes is well known. Conventionally, optical methods are used to derive information on by obtaining gravity (GW) characteristics. Optical measurement techniques use airglow emissions as tracers obtain such that correspond altitudes from where emanate. However, this paper, we describe a method using radio technique (digisonde) GW behavior. It involves monitoring variations heights isoelectron densities...
Abstract On 12 October 2020 and 26 December 2021, NASA's Global‐scale Observations of the Limb Disk (GOLD) mission observed differently shaped equatorial plasma bubbles (EPBs) simultaneously within ∼10° longitude, near subsatellite point over Atlantic, respectively which is unusual. 2020, three EPBs with differing curvatures were in a ∼12° longitude sector. The westside EPB was curved toward east, C‐shape. middle straight. eastside westward, reversed In second case, smaller range ∼6°...
Abstract Vertical drift (E × B) over the geomagnetic equator of Earth is one fundamental parameters that governs equatorial electrodynamics, which responsible for formation large‐scale phenomena in low and latitudes. We present a novel approach using ground‐based optical neutral oxygen dayglow emission intensity measurements to estimate daytime vertical drifts. The diurnal patterns intensities at OI 557.7, 630.0, 777.4 nm wavelengths obtained from low‐latitude location, Hyderabad (78.4 ° E,...
Noise characteristics of a Read Avalanche diode are analyzed by incorporating the tunneling mechanism electron into avalanche mechanism. Analytical expressions presented for mean square noise voltage and measure in MITATT (mixed transit time) mode operation. A wide band gap semiconductor (4H-SiC) based is considered to study effect on negative conductance. While exhibiting enough potential 4H-SiC be used as terahertz source power mode, our results record 35.18 dB at frequency 1.5 THz.