A5030435856- Solar and Space Plasma Dynamics
- Planetary Science and Exploration
- Astro and Planetary Science
- Atmospheric Ozone and Climate
- Calibration and Measurement Techniques
- Ionosphere and magnetosphere dynamics
- Solar Radiation and Photovoltaics
- Space Science and Extraterrestrial Life
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Atmospheric and Environmental Gas Dynamics
- solar cell performance optimization
- Spaceflight effects on biology
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Space exploration and regulation
- Spacecraft Design and Technology
- Photocathodes and Microchannel Plates
- Scientific Research and Discoveries
- Photovoltaic System Optimization Techniques
- Oil, Gas, and Environmental Issues
- Shoulder Injury and Treatment
- Laser-induced spectroscopy and plasma
- Spacecraft and Cryogenic Technologies
- Space Satellite Systems and Control
University of Colorado Boulder
2015-2024
Laboratory for Atmospheric and Space Physics
2015-2024
Goddard Space Flight Center
2023-2024
University of California, Berkeley
2023
Virginia Tech
2023
University of Iowa
2019-2020
Science and Engineering Research Board
2018
Government of India
2018
Indian Institute of Science Education and Research Kolkata
2018
Indian Centre for Space Physics
2018
The Solar EUV Experiment (SEE) is one of four scientific instruments on the NASA Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) spacecraft, which has been simultaneously observing Sun and Earth's upper atmosphere since January 2002. SEE instrument measures irradiance highly variable, solar extreme ultraviolet (EUV) radiation, major energy sources for atmosphere. primary data product spectral irradiances from 0.1 to 194 nm in 1 intervals that are fundamental TIMED mission's...
The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to Earth's upper atmosphere, strongly impacting geospace environment, affecting satellite operations, communications, and navigation. Extreme Variability Experiment (EVE) onboard NASA Solar Dynamics Observatory (SDO) will measure EUV irradiance from 0.1 105 nm with unprecedented spectral resolution (0.1 nm), temporal cadence (ten seconds), accuracy (20%). EVE includes several instruments: Multiple Grating...
Abstract We report on the in‐flight performance of Solar Wind Ion Analyzer (SWIA) and observations Mars‐solar wind interaction made during Mars Atmosphere Volatile EvolutioN (MAVEN) prime mission a portion its extended mission, covering 0.85 Martian years. describe data products returned by SWIA discuss proper handling measurements with different mechanical attenuator states telemetry modes, effects penetrating scattered backgrounds, limited phase space coverage, multi‐ion populations...
Coupling between the lower and upper atmosphere, combined with loss of gas from atmosphere to space, likely contributed thin, cold, dry modern Mars. To help understand ongoing ion Mars Atmosphere Volatile Evolution (MAVEN) spacecraft made comprehensive measurements ionosphere, interactions Sun solar wind during an interplanetary coronal mass ejection impact in March 2015. Responses include changes bow shock magnetosheath, formation widespread diffuse aurora, enhancement pick-up ions....
The Earth's thermosphere and ionosphere constitute a dynamic system that varies daily in response to energy inputs from above below. This can exhibit significant within an hour changes those inputs, as plasma fluid processes compete control its temperature, composition, structure. Within this system, short wavelength solar radiation charged particles the magnetosphere deposit energy, waves propagating lower atmosphere dissipate. Understanding global-scale of thermosphere-ionosphere (T-I)...
The IHY2007 Whole Heliosphere Interval (WHI) for solar Carrington Rotation 2068 (20 March to 16 April 2008) has been very successful in obtaining a wide variety of solar, heliospheric, and planetary observations during times cycle minimum conditions. One these efforts is the generation irradiance reference spectra (SIRS) from 0.1 nm 2400 using combination satellite sounding rocket observations. These include daily TIMED Solar Extreme ultraviolet Experiment (SEE) Radiation Climate (SORCE)...
The extraordinary solar storms between 18 October 2003 and 5 November include over 140 flares, primarily from two different large sunspot groups. There were 11 X‐class flares during this period, including an X17 flare on 28 X28 4 2003. is the largest since GOES began its X‐ray measurements in 1976. (full‐disk) irradiance these was observed by instruments aboard NASA Solar Radiation Climate Experiment (SORCE) spacecraft Thermosphere, Ionosphere, Mesosphere, Energetics, Dynamics (TIMED)...
The Flare Irradiance Spectral Model (FISM) is an empirical model developed for space weather applications that estimates the solar irradiance at wavelengths from 0.1 to 190 nm 1 resolution with a time cadence of 60 s. This high enough temporal variations due flares, where few accurate measurements these exist, as well cycle and rotation variations. FISM modeling daily component variations, including rotation, was topic first paper (Chamberlin et al., 2007). flare includes both impulsive...
The solar photon output from the Sun was once thought to be constant but is now known vary considerably over timescales seconds during flares years due cycle. This especially true in wavelengths shorter than 208 nm (Al ionization edge), where measurements and models of irradiance at these short are needed. time‐variant drives physical changes Earth's atmosphere that can affect many things including GPS accuracy satellite drag rates. Flare Irradiance Spectral Model (FISM) an empirical model...
New solar extreme-ultraviolet (EUV) irradiance observations from the NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment provide full coverage in range 0.1 to 106 nm and continuously at a cadence of 10 s for spectra resolution even faster, 0.25 s, six bands. These can be decomposed into four distinct characteristics during flares. First, emissions that dominate flare's impulsive phase are transition region emissions, such as He ii 30.4 nm. Second, hot coronal above 5 MK gradual...
Abstract Solar extreme ultraviolet (EUV) radiation is a primary energy input to the Mars atmosphere, causing ionization and driving photochemical processes above approximately 100 km. Because solar EUV varies with wavelength time, measurements must be spectrally resolved accurately quantify its impact on atmosphere. The Atmosphere Volatile EvolutioN (MAVEN) Monitor (EUVM) measures irradiance incident atmosphere in three bands. These bands drive spectral variability model called Flare...
Abstract Mars dayside thermospheric temperature and scale height trends were examined using measurements from the Neutral Gas Ion Mass Spectrometer (NGIMS) Imaging Ultraviolet Spectrograph (IUVS) on Atmosphere Volatile EvolutioN (MAVEN) spacecraft. Average heights (over 150–180 km for solar zenith angles ≤75°) several different sampling periods obtained each instrument. NGIMS IUVS found to be in good agreement, with both showing decreasing after perihelion reaching a low value near aphelion...
Abstract We present the results of an initial effort to statistically map fluxes planetary ions on a closed surface around Mars. Choosing spherical shell ~1000 km above planet, we both outgoing and incoming ion (with energies >25 eV) over 4 month period. The show net escape behind Mars strong escaping from northern hemisphere with respect solar wind convection electric field. Planetary also travel toward return are particularly in southern field hemisphere. obtain lower bound estimate for...
Abstract Photochemical escape of atomic oxygen is thought to be one the dominant channels for Martian atmospheric loss today and played a potentially major role in climate evolution. Mars Atmosphere Volatile Evolution Mission (MAVEN) first mission capable measuring, situ, relevant quantities necessary calculate photochemical fluxes. We utilize 18 months data from three MAVEN instruments: Langmuir Probe Waves, Neutral Gas Ion Mass Spectrometer, SupraThermal And Thermal Composition. From these...
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...
Abstract We report a comprehensive study of Mars dayglow observations focusing on upper atmospheric structure and seasonal variability. analyzed 744 vertical brightness profiles comprised ∼109,300 spectra obtained with the Imaging Ultraviolet Spectrograph (IUVS) aboard Atmosphere Volatile EvolutioN (MAVEN) satellite. The emission show features similar to previous UV measurements at Mars. find significant drop in thermospheric scale height temperature between L S = 218° 337–352°, attributed...
The Mars Atmosphere and Volatile Evolution (MAVEN) mission, during the second of its Deep Dip campaigns, made comprehensive measurements martian thermosphere ionosphere composition, structure, variability at altitudes down to ~130 kilometers in subsolar region. This altitude range contains diffusively separated upper atmosphere just above well-mixed atmosphere, layer peak extreme ultraviolet heating primary reservoir for atmospheric escape. In situ reveal previously unmeasured populations...
Abstract The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft has been continuously observing the variability of solar soft X‐rays EUV irradiance, monitoring upstream wind interplanetary magnetic field conditions measuring fluxes energetic ions electrons since its arrival to Mars. In this paper, we provide a comprehensive overview space weather events observed during first ∼1.9 years science mission, which includes description heliospheric sources activity. To illustrate variety...
Abstract We study the Mars Atmosphere and Volatile Evolution spacecraft observations of Martian planetary ion escape during two time periods: 11 November 2014 to 19 March 2015 4 June 24 October 2015, with focus on understanding seasonal variability in response solar extreme ultraviolet (EUV) flux. organize >6 eV O + data by upstream electric field direction estimate rates through plume tail. To investigate dependence EUV flux, we constrain wind dynamic pressure interplanetary magnetic...
Abstract The Flare Irradiance Spectral Model (FISM) is an important tool for estimating solar variability a myriad of space weather research studies and applications, FISM Version 2 (FISM2) recently was released. FISM2 empirical model the ultraviolet irradiance created to fill spectral temporal gaps in satellite observations. estimates variations due cycle, rotations, flares. major improvement provided by that it based on multiple new, more accurate instruments have now captured almost full...
[1] New models of solar extreme ultraviolet (EUV) irradiance variability are constructed in 1 nm bins from 0 to 120 using multiple regression the Mg II and F10.7 activity indices with observations made during descending phase cycle 23. The have been used reconstruct EUV spectra daily since 1950, annually 1610, forecast estimate future levels 24. A two-component model developed by scaling observed rotational modulation two underestimates changes that Solar Experiment (SEE) reports at...