On the basis of S4max data retrieved from COSMIC GPS radio occultation measurements, the long-term climatology of the intensity of E_s layers is investigated for the period from December 2006 to January 2014. Global maps of E_s intensity show the high-spatial-resolution geographical distribution and strong seasonal dependence of E_s layers. The maximum intensity of E_s occurs over the mid-latitudes, and its value in summer is 2–3 times larger than that in winter. A relatively strong E_s layer is observed at the North Pole and South Pole, with a distinct boundary dividing the mid-latitudes and high latitudes along the 60–80^∘ geomagnetic latitude band. The simulation results show that the convergence of vertical ion velocity could partially explain the seasonal dependence of E_s intensity. Furthermore, some disagreements between the distributions of the calculated divergence of vertical ion velocity and the observed E_s intensity indicate that other processes, such as the vertical motions of gravity waves, magnetic-field effects, meteoric mass influx into Earth's atmosphere, and the chemical processes of metallic ions, should also be considered as they may also play an important role in the spatial and seasonal variations in E_s layers.

The ionospheric sporadic E (Es) layer has a significant impact on the global positioning system (GPS)/global navigation satellite system (GNSS) signals. These influences on the GPS/GNSS signals can also be used to study the occurrence and characteristics of the Es layer on a global scale. In this paper, 5.8 million radio occultation (RO) profiles from the FORMOSAT-3/COSMIC satellite mission and ground-based observations of Es layers recorded by 25 ionospheric monitoring stations and held at the UK Solar System Data Centre at the Rutherford Appleton Laboratory and the Chinese Meridian Project were used to derive the hourly Es critical frequency ( f _o Es) data. The global distribution of f _o Es with a high spatial resolution shows a strong seasonal variation in f _o Es with a summer maximum exceeding 4.0 MHz and a winter minimum between 2.0 and 2.5 MHz. The GPS/GNSS RO technique is an important tool that can provide global estimates of Es layers, augmenting the limited coverage and low-frequency detection threshold of ground-based instruments. Attention should be paid to small f _o Es values from ionosondes near the instrumental detection limits corresponding to minimum frequencies in the range 1.28–1.60 MHz.

We present the proposed strategic study, ‘Integrated elements for Martian life signature exploration’, to support the sampling and identification of any potential biosignatures in compliance with the engineering constraints of the Tianwen-3 mission.

The intense plasma irregularities within the ionospheric sporadic E (E_s) layers at 90–130 km altitude have a significant impact on radio communications and navigation systems. As a result, the modeling of the E_s layer is very important for the accuracy, reliability, and further applications of modern real‐time global navigation satellite system precise point positioning. In this study, we have constructed an empirical model of the E_s layer using the multivariable nonlinear least‐squares‐fitting method, based on the S4max from Constellation Observing System for Meteorology, Ionosphere, and Climate satellite radio occultation measurements in the period 2006–2014. The model can describe the climatology of the intensity of E_s layers as a function of altitude, latitude, longitude, universal time, and day of year. To validate the model, the outputs of the model were compared with ionosonde data. The correlation coefficients of the hourly f_oEs and the daily maximum f_oEs between the ground‐based ionosonde observations and model outputs at Beijing are 0.52 and 0.68, respectively. The model can give a global climatology of the intensity of E_s layers and the seasonal variations of E_s layers, although the E_s layers during the summer are highly variable and difficult to accurately predict. The outputs of the model can be implemented in comprehensive models for a description of the climatology of E_s layers and provide relatively accurate information about the global variation of E_s layers.

Long-lived metallic ions in the Earth's atmosphere (ionosphere) have been investigated for many decades. Although the seasonal variation in ionospheric “sporadic E” layers was first observed in the 1960s, the mechanism driving the variation remains a long-standing mystery. Here, we report a study of ionospheric irregularities using scintillation data from COSMIC satellites and identify a large-scale horizontal transport of long-lived metallic ions, combining the simulations of the Whole Atmosphere Community Climate Model with the chemistry of metals and ground-based observations from two meridional chains of stations from 1975–2016. We find that the lower thermospheric meridional circulation influences the meridional transport and seasonal variations of metallic ions within sporadic E layers. The winter-to-summer meridional velocity of ions is estimated to vary between −1.08 and 7.45 m/s at altitudes of 107–118 km between 10–60^∘ N. Our results not only provide strong support for the lower thermospheric meridional circulation predicted by a whole atmosphere chemistry–climate model, but also emphasize the influences of this winter-to-summer circulation on the large-scale interhemispheric transport of composition in the thermosphere–ionosphere.