Horizontal Ionospheric Electron Density Gradients Observed by FORMOSAT-3/COSMIC TIP: Spatial Distributions and Effects on VLF Wave Propagation at Mid-Latitudes

We investigate the spatial variability of electron densities in the nightside ionosphere and its effects on very-low frequency (VLF) wave propagation using a suite of instruments from the FORMOSAT-3/Constellation Observing System for Meteorology Ionosphere and Climate (COSMIC) spacecraft.We use observations from the Tiny Ionospheric Photometer (TIP) instruments to infer the horizontal electron density gradients along each satellite track. We demonstrate that the OI 1356 _ radiance measured by the TIP instruments tracks the horizontal electron density structure well with high spatial resolution and unprecedented sensitivity. Accurate measurements of the horizontal electron density gradients are important for improving retrieved electron density profiles from GPS occultation and other tomographic remote sensing techniques. The processes underlying the variability in the large-scale, nightside electron density gradients are the main drivers of ionospheric weather. TIP observations reveal significant variability in both the small and large scale structure of the nightside ionosphere. The relative intensities, relative widths, and latitudinal separation of the northern and southern ionization crests of the Appleton anomalies show a high degree of longitudinal variation.We demonstrate how the TIP observations can be used to measure the horizontal gradient of the refractive index of whistler-mode VLF waves propagating in a cold, collisionless plasma. These measurements are critical for understanding how gradients in electron density associated with ionospheric structure such as depletions and the Appleton anomalies affect VLF wave propagation through the equatorial and mid-latitude ionosphere

CIRCE: Coordinated Ionospheric Reconstruction Cubesat Experiment

The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) is a collaborative space mission between the UK Defence Science and Technology Laboratory (Dstl), and the US Naval Research Laboratory (NRL) in developing small satellite ionospheric physics capability. CIRCE will characterise space weather effects on a regional scale in the ionosphere/thermosphere system. Properly characterising the dynamic ionosphere is important for a wide range of both civil and defence applications such as GPS, communications, and sensing technology. Consisting of two near-identical 6U (2x3U) CubeSat buses, the CIRCE nanosatellites will fly in a lead-follow tandem configuration in co-planar near-polar orbits at 500km altitude. Provided by Blue Canyon Technologies (BCT), the two buses will use differential drag to achieve and maintain an in-track separation of between 250 and 500km, allowing short time-scale dynamics to be observed in-situ. These nanosatellites each carry a complement of 5 individual scientific instruments, contributed from academic, industrial, and government partners across the UK and US. Scheduled to launch in 2021 via the US Department of Defence Space Test Program, the two CIRCE satellites will provide observations to enable a greater understanding of the driving processes of geophysical phenomena in the ionosphere/thermosphere system, distributed across a wide range of latitudes, and altitudes, as the mission progresses

Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome

Tomographic Reconstruction of the Low-Latitude Nighttime Electron Density Using FORMOSAT-3/COMSIC Radio Occultation and UV Photometer Data

The Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) is a constellation of six microsatellites that was launched into low-Earth orbit on 14 April 2006. Each FORMOSAT-3/COSMIC satellite contains a GPS Occultation Experiment (GOX) GPS receiver and a Tiny Ionospheric Photometer (TIP), which measure the ionosphere. In previous papers of Dymond and Thomas (2001) and Dymond et al. (2000), an algorithm for tomographically inverting GPS occultation and UV radiometer measurements has been presented. We apply this algorithm to the inversion of recently acquired FORMOSAT-3/COSMIC data and present the results

(Table 1) Argon dating of ash layers from DSDP Hole 18-178

Ash layers from Deep Sea Drilling Project site 178 in the northeast Pacific Ocean have been dated by the 40Ar-39Ar stepwise heating technique to resolve published discrepancies concerning the length of time explosive volcanism has affected the eastern Aleutian arc and Alaskan Peninsula. The results of the investigation indicate that the record of ash-fall deposition at site 178 extends back at least 6.5 m.y. Assuming that 6.5 m.y. ago marks the onset of renewed calc-alkalic volcanism of the volcanic arc, proposed models of continuous and discontinuous motion between the Pacific and North American lithospheric plates can be evaluated. If appreciable time elapsed between the onset of subduction and the onset of arc volcanism, the 6.5-m.y. record of ash-fall deposition in the north-east Pacific is most compatible with models of continuous plate motion throughout late Cenozoic time

Observations of the Ionosphere Using the Tiny Ionospheric Photometer

The Tiny Ionospheric Photometer (TIP) on the Constellation Observing System for Meteorology, Ionosphere, and Climate (FORMOSAT-3/COSMIC) characterizes the nighttime ionosphere using 135.6-nm radiative recombination emission. TIP measures horizontal structure of the ionosphere with high precision and high spatial resolution. Latitudinal, longitudinal, and temporal distribution of the nighttime ionosphere is specified.We present a review of ionospheric observations made with TIP during the first five months of operation. Comparisons are made with other ionospheric sensors in order to validate the TIP observations and to demonstrate TIP resolution and sensitivity performance. Equatorial anomalies observed by TIP are compared with estimates of the E ___nB vertical drift during the post-sunset pre-reversal enhancement in the Peruvian sector. Low latitude irregularity structures observed by TIP are compared with measurements from ground-based sensors including: imaging photometers, ionosonde, and UHF scintillation receivers. Detailed measurements of low latitude density depletion depth and width are provided. Global ionospheric morphology observed by TIP is compared with similar observations by COSMIC radio occultation, and the GAIM model. The complexity of the underlying neutral winds is revealed by the TIP ionospheric morphology

Ionospheric Electron Density Concurrently Derived by TIP and GOX of FORMOSAT-3/COSMIC

The tiny ionospheric photometer (TIP) and GPS occultation experiment (GOX) onboard FORMOSAT-3/COSMIC (F3/C) are employed to measure the OI 135.6 nm intensities in the nadir direction and the total electron content (TEC) between the F3/C and GPS satellite in the ionosphere, respectively. Due to its very high sensitivity ~600 counts/Rayleigh and rather narrow nadir pointing 3.8___ncircular field-of-view, the TIP provides accurate characterization of ionospheric electron density gradients in the horizontal direction. Meanwhile, a technique of the low earth orbit (LEO) tomography is applied to analyze theGOX data obtaining the 3D distribution of ionosphere electron density. Here, we combine the two observations to carry out the LEO-TIP tomographic inversions, and demonstrate that the peak electron density (NmF2) retrieved from the TIP combined together with the peak altitude (hmF2) information from the LEO tomography profiles provides more realistic electron density

Coordinated Ionospheric Reconstruction CubeSat Experiment (CIRCE),

The UK’s Defence Science and Technology Laboratory (Dstl) is partnering with the US Naval Research Laboratory (NRL) on a joint mission to launch miniature sensors that will advance space weather measurement and modelling capabilities. The Coordinated Ionospheric Reconstruction Cubesat Experiment (CIRCE) comprises two 6U cube-satellites that will be launched into a near-polar low earth orbit (LEO), targeting 500 km altitude, in 2021. The UK contribution to CIRCE is the In situ and Remote Ionospheric Sensing (IRIS) suite, complementary to NRL sensors, and comprising three highly miniaturised payloads provided to Dstl by University College London (UCL), University of Bath, and University of Surrey/Surrey Satellite Technology Ltd (SSTL). One IRIS suite will be flown on each satellite, and incorporates an ion/neutral mass spectrometer, a tri-band global positioning system (GPS) receiver for ionospheric remote sensing, and a radiation environment monitor. From the US, NRL have provided two 1U Triple Tiny Ionospheric Photometers (Tri-TIPs) on each satellite (Nicholas et al., 201