Xuguang Cai

ORCID: 0000-0003-4632-1697
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About
Contact & Profiles
Research Areas
  • Ionosphere and magnetosphere dynamics
  • Solar and Space Plasma Dynamics
  • Earthquake Detection and Analysis
  • Atmospheric Ozone and Climate
  • Geomagnetism and Paleomagnetism Studies
  • Geophysics and Gravity Measurements
  • GNSS positioning and interference
  • Astro and Planetary Science
  • Oceanographic and Atmospheric Processes
  • Meteorological Phenomena and Simulations
  • Tropical and Extratropical Cyclones Research
  • Ocean Waves and Remote Sensing
  • Atomic and Molecular Physics
  • Adsorption, diffusion, and thermodynamic properties of materials
  • earthquake and tectonic studies
  • Climate variability and models
  • NMR spectroscopy and applications
  • Environmental Impact and Sustainability
  • Atmospheric aerosols and clouds
  • Mass Spectrometry Techniques and Applications
  • Asphalt Pavement Performance Evaluation
  • Fire Detection and Safety Systems
  • Seismic Waves and Analysis
  • Spacecraft Design and Technology
  • Forest ecology and management

Laboratory for Atmospheric and Space Physics
2019-2025

University of Colorado Boulder
2022-2025

University of Colorado System
2022-2025

Computational Physics (United States)
2024

High Altitude Observatory
2020-2023

NSF National Center for Atmospheric Research
2020-2023

University Corporation for Atmospheric Research
2020

Utah State University
2014-2019

Abstract After days of intense solar activity, active region AR3664 launched seven CMEs toward Earth producing an extreme G5 geomagnetic storm commencing at 17:05 UT on 10 May 2024. The impacted power grids, disrupted precision navigational systems used by farming equipment, and generated aurora seen around the globe. produced remarkable effects composition, temperature, dynamics in Earth's thermosphere that were observed NASA's Global‐scale Observations Limb Disk (GOLD) mission are reported...

10.1029/2024gl110506 article EN cc-by-nc-nd Geophysical Research Letters 2024-08-16

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...

10.1029/2020ja027823 article EN Journal of Geophysical Research Space Physics 2020-05-23

Abstract We conduct observational and modeling studies of thermospheric composition responses to weak geomagnetic activity (nongeomagnetic storms). found that the O N 2 column density ratio (∑O/N ) in part Northern Hemisphere measured by Global‐scale Observations Limb Disk (GOLD) exhibited large long‐lived depletions during May June 2019. The reached 30% quiet time values, extended equatorward 10°N lasted more than 10 hr. Furthermore, numerical simulation results are similar these...

10.1029/2020gl088838 article EN publisher-specific-oa Geophysical Research Letters 2020-09-14

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)...

10.1029/2022ja030527 article EN cc-by-nc Journal of Geophysical Research Space Physics 2022-05-28

Abstract The National Aeronautics and Space Administration Global‐scale Observations of the Limb Disk (GOLD) mission observed a unique structure thermospheric column density ratio O to N 2 (∑O/N ) during geomagnetic storm on day year (DOY) 130 (May 10) DOY 132 in 2019. percentage difference ∑O/N between time (DOY 131) quiet 128) had relatively enhanced region sandwiched by two depleted regions over North America Atlantic Ocean Northern Hemisphere. This is called neutral tongue here. Center...

10.1029/2020ja028817 article EN Journal of Geophysical Research Space Physics 2021-04-25

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...

10.1029/2022ja031002 article EN cc-by-nc-nd Journal of Geophysical Research Space Physics 2023-03-01

Abstract We conducted observational and modeling studies of thermospheric composition ionospheric total electron content (TEC) variations during two geomagnetically quiet periods (maximum Kp = 1.7) at solar minimum. Daytime O N 2 column density ratio (∑O/N ) observed by Global‐scale Observations the Limb Disk TEC from a network ground‐based Global Navigation Satellites System receivers both exhibited large (∼30% reference values) long‐lived (5–11 h) day‐to‐day in roughly same mid‐latitude...

10.1029/2021gl093300 article EN Geophysical Research Letters 2021-05-21

We examine characteristics of the seasonal variation thermospheric composition using column number density ratio ∑

10.1029/2022ja030496 article EN Journal of Geophysical Research Space Physics 2022-06-01

Abstract Salient depletions (30%–40% of the reference values) were observed in vertical total electron content (VTEC) from Global Navigation Satellite System (GNSS) network and topside ionosphere density Swarm satellites measurements over Western Atlantic Northeast American regions during a weak geomagnetic activity event (maximum Kp = 2.3) between Day‐of‐Year (DOY) 155 156 2019. These coincided with thermospheric Oxygen (O) to Nitrogen (N 2 ) column ratio (∑O/N by Global‐scale Observations...

10.1029/2022ja030908 article EN Journal of Geophysical Research Space Physics 2023-01-01

Abstract During the storm on 3 and 4 November 2021, Global‐scale Observations of Limb Disk (GOLD) mission observed well separated equatorial ionization anomaly (EIA) crests post sunset November, but merged EIA November. We used Whole Atmosphere Community Climate Model‐eXtended to simulate structures during two nights. The simulations show which are qualitatively consistent with GOLD observations. Numerical Ionospheric Connection Explorer neutral wind observations illustrate that formation...

10.1029/2023gl103603 article EN cc-by-nc-nd Geophysical Research Letters 2023-06-30

Abstract This work investigates mid‐ and low‐latitude ionospheric disturbances over the American sector during a moderate but geo‐effective geomagnetic storm on 13–14 March 2022 ( π ‐Day storm), using ground‐based Global Navigation Satellite System total electron content data, ionosonde observations, space‐borne measurements from Global‐scale Observations of Limb Disk (GOLD), Swarm, Defense Meteorological Program (DMSP), Ionospheric Connection Explorer (ICON) satellites. Our results show...

10.1029/2023ja031375 article EN cc-by-nc Journal of Geophysical Research Space Physics 2023-07-25

Abstract This paper investigates the midlatitude ionospheric disturbances over American/Atlantic longitude sector during an intense geomagnetic storm on 23 April 2023. The study utilized a combination of ground‐based observations (Global Navigation Satellite System total electron content and ionosonde) along with measurements from multiple satellite missions (GOLD, Swarm, Defense Meteorological Program, TIMED/GUVI) to analyze storm‐time electrodynamics neutral dynamics. We found that main...

10.1029/2023sw003704 article EN cc-by Space Weather 2024-03-01

Abstract In this study, we conduct an in‐depth analysis of Whole Atmosphere Community Climate Model‐eXtended simulations to examine physical mechanisms the formation and evolution equatorial ionization anomaly (EIA) merging phenomenon during a storm on 4 November 2021. A quantitative reveals that rapid decay EIA crests at their poleward sides altitudes ∼200–250 km plays crucial role in day. This is due fast recombination low (∼200–250 km) as plasma are transported downward by westward...

10.1029/2024ja032896 article EN Journal of Geophysical Research Space Physics 2025-01-01

Abstract Recent studies have suggested that the major reservoir for sporadic sodium layer (Na s ) above 95 km in altitude is likely ion + within E ( lower region. However, theoretical and laboratory works demonstrated metal ion's neutralization process quite difficult 100 km, while intensive neutral layers are consistently observed region between 125 km. In this paper, multiyear observations of a Na lidar an ionosonde at Utah State University (41.7°N, 111.8°W) nearby Bear Lake Observatory...

10.1002/2014ja019942 article EN Journal of Geophysical Research Space Physics 2014-07-01

Abstract The impacts of gravity wave (GW) on the thermal and dynamic characteristics within mesosphere/lower thermosphere, especially atmospheric instabilities, are still not fully understood. In this paper, we conduct a comprehensive detailed investigation one GW breaking event during collaborative campaign between Utah State University Na lidar Advanced Mesospheric Temperature Mapper (AMTM) 9 September 2012. AMTM provides direct evidence as well horizontal parameters GWs involved, while...

10.1002/2014ja020131 article EN Journal of Geophysical Research Space Physics 2014-08-01

Abstract The National Aeronautics and Space Administration (NASA) Global‐scale Observations of the Limb Disk (GOLD) has been imaging thermosphere ionosphere since October 2018. It provides continuous measurements over a large area from its geostationary orbit. unambiguous two‐dimensional (2‐D) maps OI 135.6 nm radiance retrieved GOLD after sunset are compared with total electron content (TEC) measured by GPS receivers in American sector. observed is an indicator peak density F2 region, while...

10.1029/2019ja027767 article EN Journal of Geophysical Research Space Physics 2020-08-24

Abstract The Global‐scale observation of limb and disk mission observed an extra electron density (Ne) peak after sunset at approximately 30°S near 40°W on 4 November 2019, which is poleward immediately next to the southern equatorial ionization anomaly (EIA) crest. This Ne different from previously reported mid‐latitude peaks that occur all local times. Whole Atmosphere Community Climate Model‐eXtended captures this phenomenon. Model diagnostic analysis reveals decrease hmF2 between 15°...

10.1029/2022ja030755 article EN Journal of Geophysical Research Space Physics 2022-09-22

Abstract The Global‐scale Observation of Limb and Disk (GOLD) mission observed distinct post‐sunset, hemispherically asymmetric evolution the equatorial ionization anomaly between 40° 50°W on 19 November 2018, with southern crest shifting poleward but northern remaining in same latitude region. Whole Atmosphere Community Climate Model‐eXtended captured this phenomenon. Diagnostic analysis revealed that was due to hemispheric asymmetry plasma transport by E × B drifts neutral winds. In...

10.1029/2022ja030706 article EN publisher-specific-oa Journal of Geophysical Research Space Physics 2022-10-21

Abstract We report a new ionosphere phenomenon: Equatorial ionization anomaly (EIA) discontinuity (EIAD), based on OI 135.6 nm radiance observations from the Global Observations of Limb and Disk (GOLD), ground‐based total electron content maps in‐situ ion density data Constellation Observing System for Meteorology, Ionosphere, Climate‐2. The EIAD occurs when EIA crest has local minimum, at fixed UT, with in longitude region being weaker than that east west sides. In GOLD field‐of‐view,...

10.1029/2023gl102994 article EN cc-by-nc-nd Geophysical Research Letters 2023-05-19

Abstract In this paper, we report our findings on the correlation between neutral temperature (around mesopause) and thermospheric column density O/N 2 ratio, along with their response to geomagnetic storms above midlatitude of North America. A temperature/wind Doppler Na lidar, operating at Fort Collins, CO (41°N, 105°W), later Logan, UT (42°N 112°W), observed significant increases (temperature anomaly) 95 km (as much as 55 K 105 altitude) during four coronal mass ejection‐induced (April...

10.1002/2015gl064860 article EN Geophysical Research Letters 2015-09-11

Abstract Gravity wave packets excited by a source of finite duration and size possess broad frequency number spectrum thus span range temporal spatial scales. Observing at single location relatively close to the source, components with higher larger vertical wavelength dominate earlier times altitudes, while lower components, shorter wavelength, during latter part propagation. Utilizing observations from Na lidar Utah State University nearby Mesospheric Temperature Mapper Bear Lake...

10.1002/2015jd023685 article EN Journal of Geophysical Research Atmospheres 2015-12-02

Abstract TIMED/GUVI limb measurements and first‐principles simulations from the Thermosphere Ionosphere Electrodynamics Global Circulation Model (TIEGCM) are used to investigate thermospheric atomic oxygen (O) molecular nitrogen (N 2 ) responses in middle thermosphere on a constant pressure surface (∼160 km) November 20 21, 2003 superstorm. The consistency between GUVI observations TIEGCM simulated composition changes allows us utilize outputs storm‐time behaviors of O N systematically....

10.1029/2021ja029449 article EN publisher-specific-oa Journal of Geophysical Research Space Physics 2021-09-21

Abstract Themospheric conditions during a minor geomagnetic event of 3 and 4 February 2022 has been investigated using disk temperature ( T ) observations from Global‐scale Observations the Limb Disk (GOLD) mission model simulations. GOLD observed that increases by more than 60 K storm when compared with pre‐storm quiet days. A comparison effective temperatures eff , i.e., weighted average based on airglow emission layer) Mass Spectrometer Incoherent Scatter radar version 2 (MSIS2)...

10.1029/2022sw003349 article EN cc-by Space Weather 2023-04-01

Abstract An interhemispheric asymmetry of thermospheric Oxygen (O) to Nitrogen (N 2 ) column density ratio (∑O/N variations was observed by the Global‐scale Observations Limb and Disk (GOLD) during 3–5 November 2021 geomagnetic storm. ∑O/N depletion is more equatorward in local morning than afternoon northern hemisphere (NH), while southern (SH). The Thermosphere Ionosphere Electrodynamics General Circulation Model simulations reproduced asymmetry. impacts interplanetary magnetic field (IMF)...

10.1029/2023ja031429 article EN publisher-specific-oa Journal of Geophysical Research Space Physics 2023-09-24

Abstract A negative ionospheric storm occurred over the North American sector on 4 November 2021. By integration of hemispheric power (HP), Ionospheric Connection Explorer (ICON), Global‐scale Observations Limb and Disk global navigation satellite system total electron content (TEC) observations, a complete observation chain is obtained for first time. At 07:11 UT, prominent energy was input into high latitudes. From 11:51 to 15:49 strong southwestward neutral wind observed by ICON south...

10.1029/2024ja033091 article EN Journal of Geophysical Research Space Physics 2024-09-01
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