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Geomagnetic storm events have a strong influence on the ionosphere–thermosphere (I-T) coupling system. Analyzing the regional response process of the I-T system and its differences across the northern and southern hemispheres is an important but challenging task. In this study, we used a combination of multiple observations and a model simulation to examine the north–south hemispheric difference in the I-T coupling system in the American and Asian sectors during the geomagnetic superstorm that occurred in May 2024. Observations of the total electron content (TEC) showed that the Asian sector had negative storms in the northern hemisphere and positive storms in the southern hemisphere, a process that exacerbated the hemispheric differences in the TEC. However, both hemispheres of the American sector showed negative storms. The thermospheric composition changes also differed between the two sectors, and their variation could partially explain the hemispheric differences caused by positive and negative storms. Moreover, the influence of the thermospheric density change was less than that of the thermospheric composition. Finally, the dynamic effect of the thermospheric wind and the plasma transport processes strongly modulated the north–south differences in the TEC at nighttime in the American and Asian sectors, respectively, during this superstorm.

We proposed, for the first time, that the angle between the horizontal projection of the magnetic field line and the sunrise line (AMFS) is a crucial factor that controls predawn heating. Through quantitative analysis, we determined that both the AMFS and the length of the magnetic field line (LMF) significantly affect predawn heating. We found that an increased AMFS intensifies predawn heating, while an increased LMF counteracts it. Our research indicates that the optimal conditions for peak predawn heating occur at an AMFS of approximately 30 degrees and an LMF of about 4000 km, where the effect surpasses 400 K. Additionally, we observed that the effects of both the AMFS and the LMF on predawn heating exhibit a saturation effect. This study provides a clearer understanding of the factors driving predawn ionospheric heating, with implications for topside ionosphere research.

Abstract In this study, we utilize ICON observations from 2019 to 2022 to analyze the variability of vertical plasma drift and its relationship with the neutral winds. The results reveal that there are 19% of downward plasma drifts at 13–17 LT, which changes with seasons and longitudes. The downward plasma drift occurs less frequently compared to the contemporaneous counter electrojet during solstices. We identify the relationship between vertical plasma drifts and north foot magnetic zonal and meridional wind profiles at 90–300 km altitudes. As the vertical plasma drifts become small or downward, the zonal winds display diverse variations at the altitudes; that is, the disturbances are eastward at 95–120 km altitudes, westward at 120–160 km altitudes, and eastward above 180 km altitudes, while the meridional winds present weak changes in all altitudes. Additionally, we discuss the possible roles of the E‐ and F‐region dynamos on the vertical plasma drifts.

Abstract Vinyldiazo compounds are one of the most important synthons in the construction of a cyclic ring. Most photochemical transformations of vinyldiazo compounds are mainly focusing on utilization of their C═C bond site, while reactions taking place at terminal nitrogen atom are largely unexplored. Herein, a photocatalytic cascade radical cyclization of LBRs with vinyldiazo reagents through sequential B─N/C─N bond formation is described. The reaction starts with the addition of LBRs (Lewis base–boryl radicals) at diazo site, followed by intramolecular radical cyclization to access a wide range of important boron‐handled pyrazoles in good to excellent yields. Control experiments, together with detailed mechanism studies well explain the observed reactivity. Further studies demonstrate the utility of this approach for applications in pharmaceutical and agrochemical research.

Planetary magnetic fields can affect ionospheric plasma transport and coupling with the solar wind. In contrast to the terrestrial global magnetic field, there are only weaker and sporadic crustal magnetic fields on Mars. Many studies have indicated that Martian crustal fields can still modulate the topside ionosphere and its coupling with the solar wind. Nevertheless, it is unclear whether the crustal fields can affect the ionospheric main peak, which does not directly interact with the solar wind and is dominated by photochemical processes. In this study, the crustal field effect was identified from ionospheric measurements over unevenly distributed crustal fields. Both the intensity and configuration of the crustal fields were found to be capable of affecting the ionospheric main peak. The ionospheric peak electron density tends to decrease in the strong horizontal crustal field region. The results suggest that the crustal fields may affect the ionospheric main peak through modulating solar wind energetic particle precipitation; strong horizontal magnetic fields can partially prevent energetic particle precipitation and thus weaken impact ionization.

It has been found that the total electron content (TEC) and the ionospheric electric fields indicated by the geomagnetic data showed inconsistent changes with each other at the mid- and low latitudes in both the American and the Asian–Australian sectors during geomagnetic quiet time (GQT) from 30 November to 8 December 2019 (Kpmax = 1.7). Meanwhile, the effects of thermospheric compositions are still indistinct. In this work, we analyze the mid/low-latitude ionospheric variations during this period, utilizing multi-instrument observations. The vertical drift velocities from the Ionospheric Connection Explorer (ICON) show significant variations and are in line with the changes in TEC at low latitudes in both of the two sectors. The zonal electric fields are supposed to play the main role in the TEC changes. This is also confirmed by the ionospheric F2 layer parameters data from the ionosonde stations at Sanya in the Asian–Australian sectors. The correlation between the variations in the geomagnetic H component (ΔH) and ionospheric F-layer electric fields can be affected by solar activity levels. The geomagnetic data ΔH sometimes may not indicate the magnitude of the electric fields in the F-region ionosphere under geomagnetic quiet conditions. The column density ratio of atomic oxygen (O) to molecular nitrogen (N2) (∑O/N2) from the Global Scale Observations of the Limb and Disk (GOLD) showed a strong enhancement at mid-latitudes in the American sector on 30 November. It is speculated that the neutral compositions should make a minor contribution to the changes in TEC during this event, compared with the electric fields.

Abstract Martian topography modulated non-migrating tides play important roles in the upper atmosphere and thus in the ionosphere through their coupling, especially in their longitude variations. In this study, the neutral scale height (H n ) and ionospheric peak electron density (N m M 2 ) and height (h m M 2 ) retrieved from the MGS radio occultation measurements were used to investigate the coupling between the Martian thermosphere and ionosphere under the forcing of topography modulated tides by investigating their concurrent longitude variations. A segment of the measurements with fixed local time was selected to analyze the relationships between the longitude variations of the parameters in detail. Longitude variations of the thermosphere and ionosphere are significant though topographic fluctuations are not very prominent at high northern latitudes. Longitude fluctuations of H n and N m M 2 are nearly in anti-phase and percentage fluctuation amplitudes of H n are nearly twice as large as those of N m M 2 , which indicate the non-migrating tide forced coupling between the ionosphere and thermosphere conforms to the Chapman theory, and suggests longitude variation of N m M 2 can be used as a quantitative indicator for that of the thermal structure in the lower thermosphere. Longitude variation phases of H n and h m M 2 are also discrepant. That is due to tide vertical propagation since H n and h m M 2 depend on the atmospheric thermal structures at different height levels. The thermosphere and ionosphere show longitude variations due to the topography; however, they are dominated by inconsistent longitude components. This implies discrepant exciting and propagating efficiencies of various topography modulated tides. Graphical Abstract

Abstract Previous studies suggested that sudden stratospheric warmings (SSW) change the global atmosphere from troposphere to thermosphere/ionosphere. We report the low‐latitude O+ and H+ composition at 840‐km altitude during the 2009 SSW, with the DMSP satellite morning measurements. Our results indicate that the stratospheric variation around 30‐km altitude modulates the ion exchange between the ionosphere and protonosphere via the vertical and field‐aligned plasma drifts due to the enhanced lunar semidiurnal tides. The upward disturbance drift uplifts the ionospheric O+ into the protonosphere, and most O+ is changed to H+ via chemical coupling, while the O+/H+ transition height does not change under combined effects of the southward and upward disturbance drifts on 24–29 January. The disturbance drift turns downward, lowers the O+/H+ transition height, depletes the O+ density in the protonosphere, and the H+ at higher altitudes moves downward to supply the H+ at 840 km from 30 January to 5 February.

The most significant and fundamental feature of the ionospheric variations is the diurnal pattern of the ionosphere, which has very interesting and complicated phenomenon. In this brief review, we will introduce some works related with the ionospheric diurnal variations. Our topics includes the sunrise ionosphere with a focus on the enhancement of equatorial electric field around sunrise hours, the phenomenon of the daytime double peaks or noontime bite-out, and the nighttime enhancements in electron density, especially the summer mid-latitude nighttime anomalies represented by the Weddell Sea anomaly. We further discuss some points which are still under debate and remain elusive.

Storage of high-value agricultural products is essential to increase their added value. Exploring growers’ storage strategies for high-value agricultural products is helpful in developing the agricultural industry. In this paper, we analyzed the factors affecting growers’ storage decisions using Probit and Tobit models based on field data from 1026 grape growers in China. We conclude that the in-season price has a negative effect on growers’ storage decisions. Expected price, market risk perception and grape quality have a positive effect on storage decisions. Borrowing behavior has a positive effect on the storage decisions of large-scale growers. In addition, the higher the expected price and the greater the market risk perception, the more growers prefer long-term storage; and the better the quality of the grapes, the more growers tend to store grapes in the short term.

This study reports unexpected strong longitudinal structures from Global Navigation Satellite System (GNSS) derived total electron content (TEC) observations in the low-latitude ionosphere over Asia. The observations during 2019–2020 show diverse patterns in the zonal difference of regional TEC, even under geomagnetically quiet conditions. The TEC in the northern hemisphere occasionally exhibits drastic zonal gradients. The intense regional gradients in TEC span a longitudinal extent of about 20°. The higher values may appear on the east or the west side. Strong zonal gradients may appear in all seasons, regardless of geomagnetically quiet or active conditions. The 15 December 2019 and 16 March 2020 cases depict an intense zonal differences cluster in the narrow latitudinal band of 16°N to 28°N, spanning a regional scale smaller than the normal longitudinal structures. In contrast, the Global Ionospheric Maps (GIMs) with a longitudinal resolution of 5° show a much flatter zonal picture. Such intense and regional-scale zonal structures in the low-latitude ionosphere call for a high zonal resolution of GIMs in terms of better geographically distributed observations. Notably, no counterpart regional structures are found at the conjugated points in the southern hemisphere during the two cases. Although the physical drivers are not certain, the appearance only in the northern hemisphere possibly excludes the dominant contribution to forming the regional structures from the equatorial electric field.

The Martian ionosphere was actively detected by Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the Mars Express. The detected echo signal of the MARSIS at an epoch is presented as a function of frequency and time delay to form an ionogram. Some MARSIS ionograms have been processed to obtain the electron density profiles of the Martian topside ionosphere. Unfortunately, more than half of the records cannot be processed with current methods due to the lack of local plasma density information at spacecraft altitude. In this work, we employ a piece-wise exponent to describe the electron density profile of the Martian topside ionosphere. The piece-wise exponent used in our method can reasonably capture the altitude structure of the Martian topside ionosphere, which has been validated with the MGS and MAVEN data. In an altitude regime of lower than 200 km, the average absolute height error of the same electron density between MGS data and fitted profiles is 0.006 km, and the average relative error is 0.008%. In an altitude regime of higher than 200 km, the average absolute height error of the same electron density between MGS data and fitted profiles is 0.55 km, and the average relative error is −0.1%. Based on the altitude structure knowledge of the Martian topside ionosphere, we put forward a new method to invert electron density profiles from MARSIS ionograms with/without local plasma density information. Compared with the previous results, the average absolute difference in the peak height of the retrieved profile is 7.38 km, within the margin of the MARSIS height resolution of 13.8 km. The average relative difference is only 3%. The application of the new method can greatly improve the utilization rate of MARSIS ionogram records.

In this study, two ionospheric nighttime enhancement (INE) events at low latitudes are selected to investigate their spatial features through the observations from Global Navigation Satellite System (GNSS) receivers and ionosondes. For the first time, we present the detailed spatial pictures of premidnight and postmidnight INEs under geomagnetically quiet conditions. The two INE events have the maximum extents of about 11° × 34° and 17° × 25° (longitude × latitude), respectively. Dramatic latitudinal and longitudinal features are revealed in the two INEs. We perform a comparison between the products of Global Ionospheric Maps (GIMs) and total electron content (TEC) measurement from GNSS receivers. However, GIMs fail to capture the TEC distribution during INEs owing to their limited spatial and temporal resolution. Considering the extent of INEs from the observations, the spherical harmonic (SH) expansion adopted by the GIM models needs to upgrade the degree and order to 36. The pixel-based methods developed from two GIM models are required to reduce their grid size for higher spatial resolution. The recommended time interval is shorter than 30 min. Among seven GIMs, CODG and JPLG maps generally have the best performance in reproducing the latitudinal structure of the ionosphere.

Omega-3 polyunsaturated fatty acids (PUFA) found primarily in fish oil have been a popular supplement for cardiovascular health because they can substantially reduce circulating triglyceride levels in the bloodstream to prevent atherosclerosis. Beyond this established extracellular activity, here, we report a mode of action of PUFA, regulating intracellular triglyceride metabolism and lipid droplet (LD) dynamics. Real-time imaging of the subtle and highly dynamic changes of intracellular lipid metabolism was enabled by a fluorescence lifetime probe that addressed the limitations of intensity-based fluorescence quantifications. Surprisingly, we found that among omega-3 PUFA, only docosahexaenoic acid (DHA) promoted the lipolysis in LDs and reduced the overall fat content by approximately 50%, and consequently helped suppress macrophage differentiation into foam cells, one of the early steps responsible for atherosclerosis. Eicosapentaenoic acid, another omega-3 FA in fish oil, however, counteracted the beneficial effects of DHA on lipolysis promotion and cell foaming prevention. These in vitro findings warrant future validation in vivo. [ABSTRACT FROM AUTHOR]

The coupling between the ionosphere and plasmasphere is not known well during the quiet and storm times. The topside ionosphere ion composition reflects the exchange between the ionosphere and plasmasphere. We used the DMSP satellite observations to show the changes of the 840 km altitude H+ and O+ ions at ~3-6 LT in the mid- and low-latitudes on 20-31 August 2018 where a storm occurred on 25 August. The H+ was the main ion at 3-4 LT, and its concentration presented two peaks around 40°N/S magnetic latitudes on 20-24 August. The H+ concentration strongly lessened for more than five days around 40°N/S magnetic latitudes in the recovery phase of the storm on 26-30 August. Further, the enhancement and reduction of the H+ concentration persisted mainly in the Pacific and Asian sectors. The O+ density increased in Northern Hemisphere at 6:36 LT, and the H+ concentration showed the maximum around the magnetic equator during the quiet times, while the H+ concentration still mainly reduced around 40°N/S and stronger at 40°S in the recovery phase. The plasmaspheric total electron content showed a peak around the magnetic equator on 20-24 August, and the peak was weakened or disappeared on 26-30 August. The plasmasphere might be the principal sources for the mid-latitude H+ enhancement along the geomagnetic field lines during the quite times and the storm-time suppressed plasmasphere plasma density would weaken the supply of the H+ at 840 km altitude. [ABSTRACT FROM AUTHOR]