Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Impact of the Polar Vortex on Sub‐Seasonal O/N 2 Variability in the Lower Thermosphere Using GOLD and WACCM‐X
Abstract We provide observational evidence that the stability of the stratospheric Polar vortex (PV) is a significant driver of sub‐seasonal variability in the thermosphere during geomagnetically quiet times when the PV is anomalously strong or weak. We find strong positive correlations between the Northern Annular Mode (NAM) index and subseasonal (10–90 days) Global Observations of the Limb and Disk (GOLD) O/N2perturbations at low to mid‐northern latitudes, with a largest value of +0.55 at ∼30.0°N when anomalously strong or weak (NAM >2.5 or < −2.1) vortex times are considered. Strong agreement for O/N2variability and O/N2‐NAM correlations is found between GOLD observations and the Whole Atmosphere Community Climate Model with thermosphere‐ionosphere eXtension (WACCM‐X) simulations, which is then used to delineate the global distribution of O/N2‐NAM correlations. We find negative correlations between subseasonal variability in WACCM‐X O/N2and NAM at high northern and southern latitudes (as large as −0.54 at ∼60.0°S during anomalous vortex times). These correlations suggest that PV driven upwelling at low latitudes is accompanied by corresponding downwelling at high latitudes in the lower thermosphere (∼80–120 km), which is confirmed using calculations of residual mean meridional circulation from WACCM‐X.  more » « less
Award ID(s):
1753214 2149695
PAR ID:
10527632
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
AGU
Date Published:
Journal Name:
Journal of Geophysical Research: Space Physics
Volume:
129
Issue:
6
ISSN:
2169-9380
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, Frontiers in Astronomy and Space Sciences)
    We quantify the short-term (<30 day) variability of column O/N 2 measured by GOLD from January 2019 to August 2022 for various geomagnetic activity conditions. We find enhanced variabilities at high latitudes during active (Kp ≥ 3.0) times and weak but statistically significant variabilities at low latitudes. For active times, the largest absolute variability of O/N 2 ratio is 0.14 and the largest relative variability is 20.6% at ∼60.0°N in Fall, which are about twice those of quiet times. The variability at higher latitudes can be larger than that of lower latitudes by a factor of 5–8. We further quantify contributions of magnetospheric forcing to O/N 2 variability in the Ionosphere-Thermosphere region by correlating O/N 2 perturbations with Dst. During geomagnetic active times, positive correlations as large as +0.66 and negative correlations as large as −0.65 are found at high and low latitudes, respectively, indicative of storm-induced O and N 2 upwelling at high latitudes and down welling at low latitudes. During quiet times, correlations between O/N 2 perturbations and Dst become insignificant at all latitudes, implying a more substantial contribution from below. O/N 2 variabilities maximize in Fall and decrease towards Summer, while correlations maximize in Spring/Summer and decrease in Winter/Spring, which may be related to seasonal variations of geomagnetic activity and mean circulation. 
    more » « less
  2. ; ; ; ; (, Geophysical Research Letters)
    Abstract This study presents a full‐period imaging of the thermospheric composition response to the 14 October 2023 annular solar eclipse, combining GOLD (Global‐scale Observations of the Limb and Disk) far‐ultraviolet observations with solar‐irradiance‐driven WACCM‐X (Whole Atmosphere Community Climate Model with thermosphere–ionosphere extension) modeling. GOLD detected up to 80K cooling and >30% airglow reductions in the umbra, with ΣO/N2increasing ∼20%. WACCM‐X reproduced overall trends but overestimated the ΣO/N2increase by ∼5%, underestimated the cooling by ∼60K, and showed slower recovery. The discrepancies between the WACCM‐X simulations and the GOLD observations are further corroborated by supplementary TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) observations. The model‐data comparison reveals that eclipse‐induced thermospheric changes arise from coupled photochemical, dynamical, and radiative processes, providing new insight into the atmospheric response to abrupt solar forcing and refining theoretical models. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Journal of Geophysical Research: Space Physics)
    Abstract The geomagnetic storm on February 3, 2022 caused the loss of 38 Starlink satellites of Space‐X. The Global‐scale Observations of the Limb and Disk (GOLD) observations and Multi‐Scale Atmosphere Geospace Environment (MAGE) model simulations are utilized to investigate the thermospheric composition responses to the Space‐X storm. The percentage difference of the GOLD observed thermospheric O and N2column density ratio (∑O/N2) between the storm time (February 3, Day‐of‐Year [DOY] 34) and quiet time (DOY 32) shows a depletion region in the local noon sector mid‐high latitudes in the southern hemisphere, which corresponds to the east side of GOLD field‐of‐view (FOV). This is different from the classic theory of thermospheric composition disturbance during geomagnetic storms, under which the ∑O/N2depletion is usually generated at local midnight and high latitudes, and thus, appear on the west side of GOLD FOV. MAGE simulations reproduce the observations qualitatively and indicate that the ∑O/N2depletion is formed due to strong upwelling in the local morning caused by strong Joule heating. Interestingly, enhanced equatorward winds appear near local midnight, but also in the local morning sector, which transports ∑O/N2depletion equatorward. The depletion corotates toward the local afternoon and is observed in the GOLD FOV. The equatorward winds in the local morning are due to the ion‐neutral coupling under the conditions of a dominant positive interplanetary magnetic field east‐west component (By) during the storm. 
    more » « less
  4. ; ; (, Journal of Geophysical Research: Space Physics)
    Abstract The Quasi‐Biennial Oscillation (QBO) is a dominant mode of stratospheric variability and is known to modulate the variability of the ionosphere‐thermosphere (IT) system. However, the extent of its influence on the ionosphere‐thermosphere system remains uncertain due to weak signals and confounding with similar periodicities in solar flux. In this study, we investigated QBO signatures in ionosonde derived peak electron density (NmF2), GNSS total electron content (TEC), and thermospheric composition (O/N2) from the Global Ultraviolet Imager on NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite. Local empirical models are used to isolate the stratospheric QBO signature in NmF2 and TEC. Multi‐channel singular spectrum analysis is used to reveal seasonal modulation of theO/N2response to QBO. We found that the amplitude of non‐solar origin QBO in NmF2, TEC, andO/N2reaches up to 4% and exhibits an out‐of‐phase relation with stratospheric QBO phase at 30 hPa (QBO30). The TEC QBO signal shows strong regional variability, peaking over Europe. TheO/N2QBO signal shows clear seasonality with maximum correlation with QBO30 around the equinoxes. The NmF2 response to stratospheric QBO is enhanced at most stations during the September equinox. The QBO signal inO/N2at different latitudes shows maximum correlation with the stratospheric QBO at different pressure levels. Overall, the global reduction in NmF2, TEC, andO/N2during the eastward QBO phase, along with their seasonal structure, is consistent with enhanced mixing driven by migrating diurnal tide. However, the regional structure in the TEC response implies additional mechanisms with varying spatial influence and vertical extent. 
    more » « less
  5. ; ; ; ; ; (, Journal of Geophysical Research: Space Physics)
    Abstract This study examines how the breakdown of the stratospheric polar vortex influences lunar semidiurnal (M2) tides in F‐region electron density using Global Ionospheric Specification (GIS) data from the Constellation Observing System for Meteorology, Ionosphere, and Climate‐2 (COSMIC‐2). During the 2020–2021 Sudden Stratospheric Warming (SSW) event—marked by an exceptionally disrupted polar vortex—we observe up to a 16% enhancement in the M2 lunar tide at low latitudes (equatorial ionization anomaly) around 300 km altitude relative to the mean state. The response of M2 in vertical plasma drifts measured by the ion velocity meter on board the Ionospheric Connection Explorer satellite shows similar variability. Whole‐atmosphere model simulations using the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (SD‐WACCM‐X) reproduce consistent M2 tidal signatures in E‐region zonal winds, F‐region vertical drifts, and electron density. To quantify the relative contributions of electrodynamics and neutral winds, we analyzed the ion continuity equation using the National Center for Atmospheric Research Thermosphere–Ionosphere–Electrodynamics General Circulation Model with SD‐WACCM‐X as the lower boundary. Results show M2 tides impact F‐region electron densities primarily through vertical plasma drifts, which increase by ∼114% during the SSW, while transport by neutral winds rises by ∼43%. These findings confirm that vertical drifts dominate lunar tide transport, with neutral winds providing a secondary contribution. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email