We'll always have an open seminar every Thursday from 10:00 AM - finish
This week's agenda* (July 17th, 2025):
Masa's progress report
Maeda's paper review
*presenters may be changed without notice due to unforeseen circumstances
Please feel free to come and visit us* at :
W1-A-617-1, West 1 Building, 6th Floor, Ito Campus, Kyushu University (Opposite of Huixin-sensei's office)
*Please contact us beforehand if you wish to visit
News / Recent Events
Prof. Liu's feature in Kyushu University Science Salon (2025/06/25)
Recently, Prof. Liu was featured in Kyushu University Science Salon, explaining the importance of space weather in the modern world. Be sure to check out the full interview below!
Continued coverage of our recent discovery of Es intensification caused by Geomagnetic Storm (2025/06/25)
Recent work from Prof. Liu and our Assistant Prof. Qiu has made a groundbreaking discovery regarding the enhancement of sporadic E (Es) layers during major geomagnetic storms. Their research revealed that Es layers, which can adversely affect shortwave communications, become significantly enhanced during geomagnetic disturbances.
Published online in Geophysical Research Letters on April 23, 2025, this study demonstrates the importance of space weather information for the safe operation of aviation control and maritime communication systems that use shortwave radio waves, as Es layer enhancements can disrupt normal communications. Summary of the work can be found here.
Not only featured in the Kyushu University press release, our work has also gained some attention on the web, with coverage from space.com and eurekalert.org, exposing our lab's research to the general public.
Visit of Dr. Yosuke Yamazaki (2025/01/30)
Dr. Yosuke Yamazaki (GFZ, Germany) who is on a short term visit until late February, gave us a talk on his recent work on Sq (solar quiet). If you have any questions about his work, or just wanted to know what it feels like to be a scientist (FYI, he's also a Kyushu University alumni), feel free to visit Dr. Yamazaki while he's here!
Visit of Dr. Jia Yue (2025/01/20-2025/01/23)
On the week of January 20th, we got a brief visit from Dr. Jia Yue (NASA Goddard Flight Center, US) on an outreach mission by presenting to us his grueling work on the overall coupling of thermosphere and ionosphere. Later after presenting his work, some of us went jogging with him and Huixin-sensei to the beach for bottomless oysters!
Ph.D. from Max-Planck-Institute for Aeronomy in Germany in 2001. Research Associate at the National Center for Atmospheric Research, US; Alexander von Humboldt fellow at the German Research Center for Geosciences, Germany; JSPS fellow in Hokkaido University, JSPS RPD fellow in Kyoto University before taking up Professor position at Kyushu University in 2011. She is the Vice President of Kyushu Uinviersity since 2023, responsible for international collaboration on research and education.
Research keywords
Space weather, vertical coupling process through out the atmosphere-ionosphere-magnetosphere-sun system, thermosphere, ionosphere, satellite drag, magnetic storms, EISCAT radar, planetary atmosphere
The area between about 80-1000 km above the Earth surface is called the upper atmosphere, including the ionosphere and thermosphere. This is the region where International Space Station, satellites, and rockets fly, hence is the gateway to space. Distrubances of the ionosphere and thermosphere can have severe societal impact on radio communications, gobal positioning system, satellite orbit control and lifetime, space debris, and so on. This is why ionosphere/thermosphere research is the core part of "space weather" research. Space weather involves processes along the Sun-Earth chain, which can be roughly divided into "downward coupling processes driven by the Sun", "upward coupling processes driven by the meteorological weather", "plasma-neutral coupling". We study these coupling processes using ground, satellite observations, along with numerical simulations using whole atmosphere models.
Here is a short animation explaining the tug-of-war between the solar forcing from above and the terrestrial forcing from below using the example of increasing CO2 on space weather impact prented in Liu et al. 2021.
Upper Atmosphere Responses to IPCC's Worst Scenario of CO2 Increase in the 21st Century
Han Ma1,2, Huixin Liu, Hanli Liu3, Libo Liu4 (2025) (link to paper)
1Key Laboratory of Planetary Science and Frontier Technology, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
2Heilongjiang Mohe Observatory of Geophysics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
3High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO, USA
4College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
(Figure 2) The latitude‐height distribution of parameters in 2008 (the top panels) and their responses to tripled CO2 emission (the bottom panels) in June. These normalized data are a series of zonal mean value at fixed altitude and latitude. (a1, a2): atmospheric temperature (T) and its response (∆T); (b1, b2): neutral mass density (ρ) and its response (∆ρ); (c1, c2): electron density (Ne) and its response (∆Ne). The symbol “∆” represents the difference of normalized data: Y (2088)‐Y (2008).
This study uses a sophisticated climate model (CESM2/WACCM-X) to predict how Earth's upper atmosphere (100–500 km altitude) will respond to a worst-case CO₂ increase scenario by 2090, where concentrations nearly triple from ~350 ppm to ~1,000 ppm. The simulations reveal three primary effects:
First, thermospheric temperature, neutral density, and electron density decrease overall due to CO₂'s cooling effect, with electron density showing a transition from increase to decrease above ~220 km altitude. Second, the north-south (meridional) wind circulation accelerates by 5–10 m/s, especially during June, indicating a faster global wind pattern. Third, atmospheric tides—24-hour cycles weaken above 200 km but strengthen below it, while 12-hour cycles weaken throughout the thermosphere. These dynamical changes align with predictions from another model (GAIA), confirming that CO₂-induced cooling accelerates upper-atmospheric circulation. The findings help anticipate impacts on satellites, navigation systems, and space weather.
Impact of Increasing Greenhouse Gases on the Ionosphere and Thermosphere Response to a May 2024‐Like Geomagnetic Superstorm
Nicholas M. Pedatella1,2, Huixin Liu, Hanli Liu1, Adam Herrington3, Joseph McInerney1 (2025) (link to paper)
1High Altitude Observatory, NSF National Center for Atmospheric Research, Boulder, CO, USA
2COSMIC Program Office, University Center for Atmospheric Research, Boulder, CO, USA
3Climate and Global Dynamics Laboratory, NSF National Center for Atmospheric Research, Boulder, CO, USA
(Figure 4) Storm‐time change in total electron content (ΔTEC) in (a) 2016, (b) 2040, (c) 2061, and (d) 2084. The ΔTEC is calculated as the difference between the TEC on May 11 and the average TEC on May 8–9. Difference in the magnitude of the storm‐time change from the 2016 baseline in (e) 2040, (f) 2061, and (g) 2084. (h–n) Same as (a–g) except the results are for the relative storm‐time change in TEC.
Using the Community Earth System Model with thermosphere-ionosphere extension (CESM WACCM-X), this study investigates how increasing greenhouse gas concentrations affect the ionosphere and thermosphere's response to geomagnetic storms. The May 2024 geomagnetic superstorm is simulated under four different CO2 scenarios, ranging from present-day levels (403 ppmv) to nearly doubled concentrations (918 ppmv) projected for 2084. The results show that higher CO2 concentrations significantly weaken the absolute response of both the ionosphere and thermosphere to geomagnetic storms. Specifically, the thermosphere neutral density response decreases by 20-25% and the ionospheric response weakens by up to 50% as CO2 levels increase from current to future projected levels. However, when expressed as relative changes compared to background conditions, the storm responses actually strengthen with higher CO2 concentrations, primarily because the background neutral densities become much smaller in a high-CO2 atmosphere. The weakening absolute response occurs due to reduced Joule heating at higher altitudes, which is the primary energy source driving storm-time changes in the upper atmosphere. This study provides the first comprehensive assessment of how climate change may alter space weather impacts on Earth's upper atmosphere.
Sporadic-E layer responses to super geomagnetic storm 10-12 May 2024
Lihui Qiu, Huixin Liu (2025) (link to paper)
(Figure 1) Geographical distribution of the (a) daily averaged Es layer intensity derived from S4 data, (b) daily averaged Es layer intensity derived from S4 data on 11 May, (c) Es layer perturbation on 11 May. (d-f) is the same as Figure a-c, but for SNR data. The magnetic equator is indicated as a red dashed curve.
Using 37 ground-based ionosondes distributed globally and space-based COSMIC-2 radio occultation observations, this study investigates the responses of Es layers to the May 2024 super geomagnetic storm. The results show that Es layers were significantly enhanced during the recovery phase of geomagnetic storm. In addition, the enhanced Es layers mainly occurred over Southeast Asia, Australia, the South Pacific and the East Pacific. The temporal evolution of foEs disturbances over the Asian-Australian sector clearly shows the “wave propagation” characteristics from high to low latitudes, indicating that the enhancements of the Es layers are most likely caused by the disturbed neutral winds in the E region. This study presents observational evidence for the downward impacts of the geomagnetic storm on the E-region ionosphere.
Generation Of Quasi-periodic Dayside Medium Scale Traveling Ionospheric Disturbances (MSTIDs) By Intermittent Lobe Reconnection
Yating Xiong1 , Huixin Liu, Run Shi1 , Zanyang Xing2 , Sheng Lu2 , Qiang Zhang1 , Zhiwei Wang1 , Desheng Han1 (2025) (link to paper)
1State Key Laboratory of Marine Geology, School of Ocean and Earth Science, Tongji University, Shanghai, China
2Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, China
(Figure) (a-b) Polar projections of the fields of view (FOVs) of Hankasalmi radar and EISCAT Svalbard radar at 09:00 and 13:00 UT on 14 December 2012. The blue fan-shaped area represents the FOV of Hankasalmi radar beam 7. The green straight line shows the FOV of the EISCAT Svalbard radar Longyearbyen 32M, and the red five-pointed star marks the position of the EISCAT Svalbard radar. (c) Variations of the interplanetary magnetic field components BX(blue), BY (red), and BZ (black) between 08:00 and 13:00 UT. (d, e) The range-time plot of velocity and power (negative away, poleward from radar) observed by beam 7 of Hankasalmi radar in channel A on the same day.
The Medium-Scale Traveling Ionospheric Disturbances (MSTIDs) can be excited by many sources. Among those magnetic reconnections has been proposed as a potential driver for dayside MSTIDs, but direct evidence has been limited. Using ground-based radar data from the Super Dual Auroral Radar Network on December 14, 2012, we observed quasi-periodic multiple MSTIDs propagating from auroral latitudes to mid latitudes near magnetic local noon, which showed one-to-one correspondences to intermittent lobe reconnections with periodicities of about 20–30 minutes. Simultaneous EISCAT Svalbard incoherent scatter radar data revealed enhanced electric field and Joule heating within the cusp region following each lobe reconnection. These multi-instrument observations strongly suggest lobe reconnection as a possible driver for the dayside MSTID.
Modelling of three-dimensional structure and dynamics of the large-scale sporadic E layers over East Asia
Lihui Qiu, Huixin Liu (2025) (link to paper)
(Figure 1) An example of the 2-D slices of Fe+ density derived from the Es layer model, i.e., (a) horizontal slices, (c) longitudinal slices, and (d) latitudinal slices. (b) Same as Figure 3a, but at an altitude range of 100-125 km in order to show more details.
Using the Fe+ layer as a proxy for Es layer, in this study, we investigated the structural and dynamic characteristics of the large-scale Es layers extending thousands of kilometers over East Asia by using a 3-D Es layer numerical model driven by neutral winds from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension model (WACCM-X). The simulation results show that the Es layer is a tilted blanket rather than a narrow flat band. In addition, the Es layers mainly occur in the 3-D spatial position of the convergent vertical wind shear. The apparent horizontal velocity (~300-400 m/s) of Es structure is mostly westward and northward, which is different from the ion drift velocity (~100 m/s). This indicates that Es structure can develop rapidly over a large area simultaneously rather than drifting from one location to the next. COSMIC targets the locations of Es layers with all intensities that including much smaller intensity at a given time from a global perspective. The migration speed of hotspot of Es layer occurrence recorded by COSMIC satellites matches the apparent velocity. The GNSS receivers track the dense ion clusters (foEs > 14 MHz) to measure the drift direction and speed of extremely strong Es layer, which matches the ion drift velocity.
Wave Spectral Changes in the Thermosphere and Ionosphere Related to the PEDE 2018 Dust Event on Mars Observed by MAVEN NGIMS
Noritsugu Nagata, Huixin Liu, Hiromu Nakagawa* (2025) (link to paper)
*Graduate School of Science, Tohoku University, Sendai, Japan
(Figure 5) The occurrence rate of apparent wavelengths for each species obtained during two periods : the low-dust period (upper) and the global dust period (lower), where altitudes between 165 and 205 km, X-bin is on a log scale
In 2018, Mars experienced a Planet Encircling Dust Event (PEDE-2018), which had significant impacts on the atmosphere. In this study, we examined changes in wave signatures (amplitudes and apparent wavelengths) associated with PEDE-2018. In-situ density measurements from the NGIMS (Neutral and Ion Gass Mass Spectrometer) instrument on MAVEN spacecraft allowed us to analyze densities of both neutrals and ions, providing insights into ion-neutral coupling in the upper atmosphere. As shown in Figure 5, we found that the rates of larger wavelengths enhanced during PEDE-2018 for both neutrals and ions (wavelengths are apparent along MAVEN trajectory, with a much larger horizontal than vertical scale). Moreover, high correlations among the wavelengths of various species (Figure 6, not shown here) were derived under both low-dust and PEDE-2018 conditions, may implying ion-neutral coupling and common dominant wave sources.
Feel free to contact us if you're interested in joining our lab (or just wish for a casual visit).
We'll definitely give you a tour!
Prof. Huixin Liu
liu.huixin.295[at]m.kyushu-u.ac.jp
Website administrator (Oki)
rifqi.farhan.naufal.821[at]s.kyushu-u.ac.jp