Comparison of ICON O+ density profiles with electron density profiles provided by COSMIC-2 and ground-based ionosondes

In October 2019, NASA-ICON was launched to observe the low-latitude ionosphere using in-situ and remote sensing instruments, from a LEO circular orbit at about 575 km altitude. The six satellites of the radio-occultation program COSMIC-2 were also successfully launched and currently provide up to 3000 electron density profiles on a daily basis since October 1, 2019. Besides, the network of ground-based ionosondes is constantly growing and allows retrieving very accurate measurements of the electron density profile up to the peak altitude. These three sources of scientific observation of the Earth ionosphere therefore provide a very complementary set of data. We compare O+ density profiles provided during nighttime by the ICON-FUV instrument and during daytime by the ICON-EUV instrument against electron density profiles measured by COSMIC-2 and ionosondes. Co-located and simultaneous observations are compared on statistical grounds, and the differences between the several methods are investigated. Particular attention is given to the most important variables, such as the altitude and the density of the F-peak, hmF2 and NmF2. The time interval considered in this study covers the whole ICON data availability period, which started on November 16, 2019. Manual screening and scaling of ionograms is performed to ensure reliable ionosonde data, while COSMIC-2 data are carefully selected using an automatic quality control algorithm. A particular attention has been brought to the geometry of the observation, because the line-of-sight integration of both airglow and radio-occultation measurements assimilates horizontal and vertical gradients. As a consequence, the local density profiles obtained by inversion of the ICON and COSMIC-2 observation cannot be exactly assimilated to vertical measurements, such as vertical incidence soundings from ionosondes. This slightly limits the reach of the interpretation of the comparison between data of different origin. However, using similar observing geometries, the comparison of ICON and COSMIC-2 data does nevertheless provide very reliable and valuable comparisons.Combining airglow, GNSS and ionosonde data to study ionospheric irregularities over low latitude

Daily Variability in the Terrestrial UV Airglow

New capability for observing conditions in the upper atmosphere comes with the implementation of global ultraviolet (UV) imaging from geosynchronous orbit. Observed by the NASA GOLD mission, the emissions of atomic oxygen (OI) and molecular nitrogen (N2) in the 133&ndash;168-nm range can be used to characterize the behavior of these major constituents of the thermosphere. Observations in the ultraviolet from the first 200 days of 2019 indicate that the oxygen emission at 135.6 nm varies much differently than the broader Lyman-Birge-Hopfield (LBH) emission of N2. This is determined from monitoring the average instrument response from two roughly 1000 km2 areas, well separated from one another, at the same time of each day. Variations in the GOLD response to UV emissions in the monitored regions are determined, both in absolute terms and relative to a running 7-day average of GOLD measurements. We find that variations in N2 emissions in the two separate regions are significantly correlated, while oxygen emissions, observed in the same fixed geographic regions at the same universal time each day, exhibit a much lower correlation, and exhibit no correlation with the N2 emissions in the same regions. This indicates that oxygen densities in the airglow-originating altitude range of 150&ndash;200 km vary independently from the variations in nitrogen, which are so well correlated across the dayside to suggest a direct connection to variation in solar extreme-UV flux. The relation of the atomic oxygen variations to solar and geomagnetic activity is also shown to be low, suggesting the existence of a regional source that modifies the production of atomic oxygen in the thermosphere.</p

A global analysis of Y-chromosomal haplotype diversity for 23 STR loci

In a worldwide collaborative effort, 19,630 Y-chromosomes were sampled from 129 different populations in 51 countries. These chromosomes were typed for 23 short-tandem repeat (STR) loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, DYS393, DYS385ab, DYS437, DYS438, DYS439, DYS448, DYS456, DYS458, DYS635, GATAH4, DYS481, DYS533, DYS549, DYS570, DYS576, and DYS643) and using the PowerPlex Y23 System (PPY23, Promega Corporation, Madison, WI). Locus-specific allelic spectra of these markers were determined and a consistently high level of allelic diversity was observed. A considerable number of null, duplicate and off-ladder alleles were revealed. Standard single-locus and haplotype-based parameters were calculated and compared between subsets of Y-STR markers established for forensic casework. The PPY23 marker set provides substantially stronger discriminatory power than other available kits but at the same time reveals the same general patterns of population structure as other marker sets. A strong correlation was observed between the number of Y-STRs included in a marker set and some of the forensic parameters under study. Interestingly a weak but consistent trend toward smaller genetic distances resulting from larger numbers of markers became apparent.Peer reviewe

Cretaceous cephalopods of the Tethyan Himalaya of southern Tibet

Volume: 23Start Page: 79End Page: 10

Die Kreideammoniten des Glaukonitkalkes (O. Alb - O. Cenoman) des Kolah-Qazi-Gebirges s\ufcd\uf6stlich von Esfahan (Zentraliran)

Volume: 12Start Page: 87End Page: 13

Das Helvetikum-Profil im Steinbruch "An der Schanz" bei Burgberg/Allg\ue4u Lithologie, Stratigraphie und Makrofauna

Volume: 10Start Page: 555End Page: 57

ICON FUV Imager

A novel design FUV spectrographic imager is currently under construction at UC Berkeley for the payload of the Ionospheric Connection Explorer (ICON). This instrument will image the limb-view atmosphere/ionosphere with a FOV of 24x18 degrees (vertical and horizontal) tilted down by 20⁰ and looking in a direction nominally perpendicular to the spacecraft velocity. From the spacecraft altitude (575 km) the view provides coverage from sub-limb up to ~500 km limb tangent height. There is a steering mirror assembly that allows steering the view ±30⁰ with respect to the nominal direction in order to observe the nightglow emissions along the local magnetic meridian. The instrument uses the spectrographic imager principle first used on the IMAGE spacecraft in which several full two-dimensional instantaneous images are formed in specific wavelength bands. One of the two bands on ICON contains the 135.6 nm atomic oxygen emission while the other band covers the N2 LBH emission region near 157 nm. When the imager is viewing the sunlit atmosphere the instrument provides the limb altitude profile of the atmospheric O/N2 ratio. On the night side the instrument observes the 135.6 nm emission that is produced by the recombination of O+ and therefore provides a good proxy for the nighttime ionospheric density. To minimize data downlink, 6 parallel vertical stripe segments will be transmitted to the ground from both channels every 12 seconds. In addition the nighttime 135.6 nm data will be integrated as two dimensional (spacecraft orbit latitude and longitude) maps. One map is projected on a sphere at 300 km altitude while the other map projects at a surface defined by the tangent height of observation from the ICON satellite. Both maps will be integrated with motion compensation to minimize blurring due to the satellite motion

Optical design and optical properties of a VUV spectrographic imager for ICON mission

peer reviewedIn the frame of the ICON (Ionospheric Connection Explorer) mission of NASA led by UC Berkeley, CSL and SSL Berkeley have designed in cooperation a new Far UV spectro-imager. The instrument is based on a Czerny-Turner spectrograph coupled with two back imagers. The whole field of view covers [± 12° vertical, ± 9° horizontal]. The instrument is surmounted by a rotating mirror to adjust the horizontal field of view pointing by ± 30°. To meet the scientific imaging and spectral requirements the instrument has been optimized. The optimization philosophy and related analysis are presented in the present paper. PSF, distortion map and spectral properties are described. A tolerance study and alignment cases were performed to prove the instrument can be built and aligned. Finally straylight and out of band properties are discussed