Wenbin Wang

The Long-term Trend of Thermospheric Compositions from Whole Atmospheric Simulation and Satellite Observation

whawkins — Tue, 11 Nov 2025 20:32:51 +0000

The Long-term Trend of Thermospheric Compositions from Whole Atmospheric Simulation and Satellite Observation whawkins Tue, 11/11/2025 - 13:32

Author:

whawkins

Nov 11, 2025

JGR space physics: This study examines the long-term trend of column-integrated atomic oxygen to molecular nitrogen ratio, O/N2, in the upper atmosphere and investigates the cause of this long-term trend in O/N2. We first validate the feasibility of using a physics-based model for a long-term climate reanalysis by applying a model-data comparison between 2002 and 2018. O/N2 simulated by NSF NCAR's Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) and measured by Global Ultraviolet Imager (GUVI) aboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) mission is used to determine the long-term trend of O/N2 from 2002 to 2018 and validate the model result. The model and data show good agreement after removing the impact of solar irradiance and geomagnetic activity using a least-squares fitting method, revealing a decreasing trend of O/N2 of about -0.54% per decade relative to the O/N2 in 2018 in the model and about -0.45% per decade in data along the satellite orbit during the period between 2002 and 2018. A decreasing trend of global O/N2 of about -0.70% per decade is found in the model between 1960 and 2018. After that, four WACCM-X long-term simulations are performed from 1960 to 2018 to identify the cause of the decreasing trend of O/N2. The results show that this decreasing trend is mainly caused by the increase in greenhouse gas concentrations.

O/N2 measured by TIMED/GUVI and simulated by WACCM-X Case4 and their linear trends. (a) Black and grey lines are the O/N2 data derived from TIMED/GUVI and simulated by WACCM-X, respectively. (b) Dark and light green lines are the fitting curves of the black and grey lines in (a) using the least-squares fitting method with an equation that includes the annual, semi-annual, F10.7 index, and Ap index variations. (c) The blue line is the residual term of TIMED/GUVI O/N2 by subtracting the dark green line from the black line, while the cyan line is the residual term of WACCM-X O/N2 by subtracting the light green line from the grey line. (d) Red and magenta lines are the fitting results of blue and cyan lines using the least-squares fitting method with a linear equation, respectively.

Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves

whawkins — Wed, 13 Aug 2025 20:10:55 +0000

Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves whawkins Wed, 08/13/2025 - 14:10

Author:

whawkins

Aug 13, 2025

(a) 5-200 s bandpassed $S_{A//}$ mapped to the ionospheric altitude and averaged over the four-hour interval. (b) 5-200s bandpassed $S_{A//}$ in the 7 MLT plane. (c) 4.5-5.5 mHz root-integrated power (RIP) of radial electric field $E_r$ in the equatorial plane. (d) 4.5-5.5 mHz RIP of azimuthal magnetic field $B_\phi$ in the meridional plane of 7 MLT. (e-f) Field-aligned keograms of $E_{mrd}$ and $B_\phi$ along the green field line with the largest $S_{A//}$. The green curve in (b) and (d) is a magnetic field line in the 7 MLT plane connecting to the green cross in (a) which marks the location with the peak $S_{A//}$. This field line crosses the equatorial plane at the green cross in (c).

Geophysical Research Letter: Scientists have long been interested in how energy from the Sun is transferred into Earth’s space environment. The Earth's magnetosphere is an important intermediate environment between the solar wind and the upper atmosphere. Consisting of plasma and magnetic field, the magnetosphere is full of intrinsic plasma waves that are capable of energy transport, particularly a group in the frequency range of a few to a few tens Millihertz that are especially efficient in connecting the magnetosphere and the ionosphere. However, due to the global presence and propagation features of those waves, it has been very challenging with measurements from a limited number of locations to understand the efficiency of the wave based energy transfer mechanism. This study uses a first-principles computational model that can resolve the fundamental physics related to the low frequency plasma waves, to carry out idealized numerical experiments to investigate the electromagnetic energy flow in response to undulating solar wind. The theoretical study provides new understanding of the significance of the electromagnetic energy flow and its dependence on different parameters.

Penetrating electric field with/without disturbed electric fields During the 7-8 July 2022 geomagnetic storm simulated by MAGE and observed by ICON MIGHTI

whawkins — Wed, 09 Apr 2025 21:17:49 +0000

Penetrating electric field with/without disturbed electric fields During the 7-8 July 2022 geomagnetic storm simulated by MAGE and observed by ICON MIGHTI whawkins Wed, 04/09/2025 - 15:17

Author:

whawkins

Apr 9, 2025

7 July, MAGE simulation and ICON observation of zonal thermospheric winds and ion drifts. ICON MIGHTI observed zonal wind and MAGE simulations along the MIGHTI sampling points (right) are plotted. Data from each orbit are plotted according to the longitude. The starting time for each orbit is provided. The midnight is marked by blue triangles. MIGHTI data gaps are due to SAA (South Atlantic Anomaly) or day-night transitions (see Englert et al., 2023). The IMF Bz southward turning occurred after 12 UT, which is highlighted by a dashed oval. The nightside zonal wind start to see reaction in the next orbit. Not much change is seen on the dayside. The ExB meridional ion drifts (vertical upward at the magnetic equator) for each orbit are plotted on the right.

JGR Space Physics: Using a numerical model where the coupled physical processes of the magnetosphere, ionosphere, and thermosphere are represented, we simulated the nighttime ionospheric disturbances caused by electric fields that enter this system from the magnetosphere and electric fields generated internally by changes in the thermospheric winds. The former is quick to reach the low latitudes, and the latter is delayed by the slower response of the neutral winds. The coupled model and NASA satellite observation showed good agreement. The results show good capability and lend themselves to the future effort to forecasting space weather at low latitudes.

The Formation Mechanism of Merged EIA During a Storm on 4 November 2021

whawkins — Wed, 05 Feb 2025 16:29:40 +0000

The Formation Mechanism of Merged EIA During a Storm on 4 November 2021 whawkins Wed, 02/05/2025 - 09:29

Author:

whawkins

Feb 5, 2025

Nmax observed by GOLD (a, b) and NmF2 simulated by WACCM-X (c, d) at 20:10 UT on November 03-04, 2021. The red dotted lines represent the magnetic equator. The black dotted lines represent the 0° longitude. The temporal variations of NmF2 at the 0° longitude (40°S - 40°N latitude) from 9:00 UT and 24:00 UT, simulated by WACCM-X, for November 3rd (e) and 4th (f); The corresponding temporal variations of the peak distance of the South and North EIA crests in (e) and (f), for November 3rd (g) and 4th (h).

JGR-Space Physics: In this study, we conduct an in-depth analysis of Whole Atmosphere Community Climate Model-eXtended (WACCM-X) simulations to examine physical mechanisms of the formation and evolution of an equatorial ionization anomaly (EIA) merging phenomenon during a storm on November 4th, 2021. A quantitative analysis reveals that the rapid decay of the EIA crests at their poleward sides at altitudes of ~200-250 km plays a crucial role in the EIA merging during that day. This rapid decay is due to the fast recombination at low altitudes (~200-250 km) as the plasma are transported downward by the westward disturbance dynamo electric field (DDEF) and poleward neutral winds during the storm. The results suggested EIA-merging is not merely northern and southern EIA crests moving together, but it involves a crucial rapid decay of the EIA crests at their poleward sides that descended to low altitudes (rapid recombination, ~200-250 km), driven by regional electric fields and neutral winds. This study plays a crucial role in our understanding of the evolution and formation of the merged EIA on November 4th, 2021 during the storm.

SubAuroral Red Arcs Generated by Inner Magnetospheric Heat Flux and by SubAuroral Polarization Streams

whawkins — Fri, 06 Sep 2024 19:51:29 +0000

SubAuroral Red Arcs Generated by Inner Magnetospheric Heat Flux and by SubAuroral Polarization Streams whawkins Fri, 09/06/2024 - 13:51

Author:

whawkins

Sep 6, 2024

Heat flux/SAPS impacts on SAR arcs. (a-c) 6300 A column emission rates in the baseline TIEGCM run, CIMI heat flux driven TIEGCM run, and their difference in the northern hemisphere. (d-f) Same format for the southern hemisphere. (g-l) Same format for the comparison between with and without SAPS.

Geophysical Research Letters: The Earth's topside atmosphere is subject to energy inputs from the magnetosphere and solar wind. In addition to the Joule heating generated by high latitude plasma convection and energy flux carried by precipitating magnetospheric particles, magnetospheric energy can be also deposited in the ionosphere-thermosphere via heat flux, i.e., energy flows carried by low-energy thermal electrons. When hot ions in the ring current collide with the cold plasma in the plasmasphere, heat conduction occurs and the resultant heat flux is transported along geomagnetic field lines to the footprint ionosphere. The additional heating raises the electron temperature in the subauroral ionosphere and modifies the ionosphere-thermosphere states. This study uses first-principles inner magnetosphere model and ionosphere-thermosphere model to illustrate the thermodynamic coupling effects between the topside ionosphere and the magnetosphere, and compare the relative significance between the heat flux and plasma convection due to electrodynamic coupling. The numerical experiments show that the heat flux primarily increases electron temperature while subauroral plasma flow heats up both plasma and neutrals. Despite different physical mechanisms, the heat flux and subauroral plasma convection make comparable contributions to red line emission rates in the subauroral region.

HIWIND Balloon and Antarctica Jang Bogo FPI High Latitude Conjugate Thermospheric Wind Observations and Simulations

whawkins — Fri, 21 Jun 2024 18:59:58 +0000

HIWIND Balloon and Antarctica Jang Bogo FPI High Latitude Conjugate Thermospheric Wind Observations and Simulations whawkins Fri, 06/21/2024 - 12:59

Author:

whawkins

Jun 21, 2024

JGR Space Physics: Using balloon instrument in the northern hemisphere and ground based instrument in the southern hemisphere, we study the conjugacy of the thermospheric winds of high latitudes. We found that the more summer hemispheric heating alters the thermospheric winds and resulted in a double-hump feature on the dayside meridional winds. We also used model with cusp heating to simulate the winds and were able to reproduce the double-hump feature.

Thermospheric wind observations from HIWIND (northern summer) and JBS (southern winter) along with the TIEGCM simulations at the respective locations. The JBS data were shifted by 7 hours so that the local time of the JBS is approximately equal to that of HIWIND. The meridional winds from JBS were reversed so that the poleward meridional winds from JBS is positive for easy comparison with HIWIND data. The prominent double hump feature in northern hemisphere meridional winds (HIWIND, upper penal) is a result of the high energy input in the summer hemisphere.
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MAGE Model Simulation of the Pre-reversal Enhancement and Comparison with ICON and Jicamarca ISR Observations

whawkins — Fri, 21 Jun 2024 18:52:03 +0000

MAGE Model Simulation of the Pre-reversal Enhancement and Comparison with ICON and Jicamarca ISR Observations whawkins Fri, 06/21/2024 - 12:52

Author:

whawkins

Jun 21, 2024

JGR Space Physics: Using the latest coupled geospace model MAGE (Multiscale Atmosphere-Geospace Environment) and observations from Jicamarca ISR and ICON IVM instrument, we examine the pre-reversal enhancement during geomagnetic quiet time period. The MAGE shows comparable PRE to both the Jicamarca ISR and ICON observations. There appears to be a discrepancy between the Jicamarca ISR and ICON IVM with the later showed PRE about two times larger (~ 40 m/s). This is the first time that MAGE is used to simulate the PRE. The results show that the MAGE can simulate the PRE well and are mostly consistent with observations.

MAGE simulations of the equatorial vertical ion drifts (black vectors along the magnetic equator) at 23:49 UT. The MAGE simulated ExB meridional ion drift (IVM definition) sampled along the ICON satellite track (black line above the satellite track shown as the dashed line) and the IVM observed ExB meridional drift (lime or magenta vector) from 23:15 to 23:55 UT. The magenta vectors are values near 2349 UT. The PRE is visible in the simulated equatorial vertical ion drift and in both the MAGE simulated and ICON observed ExB meridional ion drifts along the satellite tracks . The background shows the nmf2 from the MAGE simulation.

Investigation of the physical mechanism of the formation and evolution of equatorial plasma bubbles during a moderate storm on September 17, 2021

whawkins — Wed, 06 Dec 2023 16:34:59 +0000

Investigation of the physical mechanism of the formation and evolution of equatorial plasma bubbles during a moderate storm on September 17, 2021 whawkins Wed, 12/06/2023 - 09:34

Author:

whawkins

Dec 6, 2023

GOLD Namx on September 16-17, 2021. Left panels show the observations on the night of September 16th, while right panels show the observations on the night of September 17th. The red dotted lines represent the magnetic dip equator.

Space Weather: We investigate in detail the occurrence and evolution of ionospheric equatorial plasma bubbles (EPBs) during a moderate storm on September 17th, 2021, using Global-scale Observation of the Limb and Disk (GOLD) observations and Whole Atmosphere Community Climate Model-eXtended (WACCM-X) simulations. GOLD observations show that there were no EPBs on September 16th before the storm but EPBs occurred after the storm commencement on September 17th. The EPBs extended to ~ 30° magnetic latitude. A diagnostic analysis of WACCM-X simulations reveals that the rapid enhancement of prompt penetration electric fields (PPEFs) after the sudden storm commencement is the main reason that triggered the occurrence of the EPBs. Further quantitative analysis shows that vertical plasma drifts, which are enhanced by the PPEF, played a dominant role in strengthening the Rayleigh-Taylor instability, leading to the occurrence of the EPBs and the large latitudinal extension of the EPBs to ~ 30° magnetic latitude during the night of September 17th.

Investigation of the GOLD Observed Merged Nighttime EIA with WACCM-X Simulations during the Storm of November 3–4, 2021

whawkins — Tue, 27 Jun 2023 20:31:42 +0000

Investigation of the GOLD Observed Merged Nighttime EIA with WACCM-X Simulations during the Storm of November 3–4, 2021 whawkins Tue, 06/27/2023 - 14:31

Author:

whawkins

Jun 27, 2023

Geophysical Research Letters: During the storm on November 3 to 4, 2021, the Global-scale Observations of the Limb and Disk (GOLD) mission observed well separated EIA crests post sunset on Nov 3, but merged EIA on Nov 4. We used the Whole Atmosphere Community Climate Model (WACCM-X) to simulate the EIA structures during the two nights. The simulations show two separated post sunset EIA crests on November 3rd but merged post sunset EIA crests on November 4th, which are qualitatively consistent with the GOLD observations. Numerical simulations and Ionospheric Connection Explorer (ICON) neutral wind observations illustrate that the formation of merged EIA crests was due to several hours of downward E × B drifts before and after sunset. Further diagnostic analysis revealed that it was mainly driven by westward electric fields caused by the disturbance dynamo electric field during the recovery phase of the storm.

Nmax observed by GOLD and NmF2 simulated by WACCM-X at 20:10 UT on November 03-04, 2021. The red dotted lines represent the magnetic equator.

Eos Editor's Highlight Features HAO Research

whawkins — Wed, 14 Jun 2023 19:06:23 +0000

Eos Editor's Highlight Features HAO Research whawkins Wed, 06/14/2023 - 13:06

Author:

whawkins

Jun 14, 2023

The research article “Atmospheric and Ionospheric Responses to Hunga-Tonga Volcano Eruption Simulated by WACCM-X”, was selected for featuring as an Editor’s Highlight on Eos.org. Fewer than 2 per cent of papers are selected to be featured in this way.

**Their research article was just published on Eos.org.

Model Output Link Correction:
The Globus connection point for the WACCM-X Hunga-Tonga simulation output, provided in the Data Availability Statement of this GRL paper (https://doi.org/10.1029/2023GL103682) is incorrect. The correct link is: Log in to use Globus Web App.
The QR code is: (See attached png file).

QR code

In addition, see HAO's "Latest Research Highlights".

The upper panels show the exponential growth of the wave amplitude and the vertical structure of the wave in zonal and meridional directions. Distinct wave modes are seen in the vertical wind responses in the mesosphere, lower thermosphere, and upper thermosphere 1.5 hours after the eruption (lower panels).

Wenbin Wang

The Long-term Trend of Thermospheric Compositions from Whole Atmospheric Simulation and Satellite Observation

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Efficiency of Electromagnetic Energy Transfer from Solar Wind to Ionosphere through Magnetospheric Ultra-Low Frequency Waves

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Penetrating electric field with/without disturbed electric fields During the 7-8 July 2022 geomagnetic storm simulated by MAGE and observed by ICON MIGHTI

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The Formation Mechanism of Merged EIA During a Storm on 4 November 2021

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SubAuroral Red Arcs Generated by Inner Magnetospheric Heat Flux and by SubAuroral Polarization Streams

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HIWIND Balloon and Antarctica Jang Bogo FPI High Latitude Conjugate Thermospheric Wind Observations and Simulations

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MAGE Model Simulation of the Pre-reversal Enhancement and Comparison with ICON and Jicamarca ISR Observations

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Investigation of the physical mechanism of the formation and evolution of equatorial plasma bubbles during a moderate storm on September 17, 2021

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Investigation of the GOLD Observed Merged Nighttime EIA with WACCM-X Simulations during the Storm of November 3–4, 2021

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Eos Editor's Highlight Features HAO Research

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