The Winchcombe fireball—That lucky survivor

On February 28, 2021, a fireball dropped ∼0.6 kg of recovered CM2 carbonaceous chondrite meteorites in South-West England near the town of Winchcombe. We reconstruct the fireball's atmospheric trajectory, light curve, fragmentation behavior, and pre-atmospheric orbit from optical records contributed by five networks. The progenitor meteoroid was three orders of magnitude less massive (∼13 kg) than any previously observed carbonaceous fall. The Winchcombe meteorite survived entry because it was exposed to a very low peak atmospheric dynamic pressure (∼0.6 MPa) due to a fortuitous combination of entry parameters, notably low velocity (13.9 km s⁻¹). A near-catastrophic fragmentation at ∼0.07 MPa points to the body's fragility. Low entry speeds which cause low peak dynamic pressures are likely necessary conditions for a small carbonaceous meteoroid to survive atmospheric entry, strongly constraining the radiant direction to the general antapex direction. Orbital integrations show that the meteoroid was injected into the near-Earth region ∼0.08 Myr ago and it never had a perihelion distance smaller than ∼0.7 AU, while other CM2 meteorites with known orbits approached the Sun closer (∼0.5 AU) and were heated to at least 100 K higher temperatures.     

Quantitative integration of 3D and 4D seismic impedance into reservoir simulation model updating in the Norne Field

The ultimate goal of reservoir simulation in reservoir surveillance technology is to estimate long-term production forecasting and to plan development and management of petroleum fields. However, maintaining reliable reservoir models which honour available static and dynamic data, involve inherent risks due to the uncertainties in space and time of the distribution of hydrocarbons inside reservoirs. Recent applications have shown that these uncertainties can be reduced by quantitative integration of seismic data into the reservoir modelling workflows to identify which areas and reservoir attributes of the model should be updated. This work aims using seismic data to reduce ambiguity in calibrating reservoir flow simulation model with an uncertain petro-elastic model, proposing a circular workflow of inverted seismic impedance (3D and 4D) and engineering studies, with emphasis on the interface between static and dynamic models. The main contribution is to develop an updating procedure for adjusting reservoir simulation response before using it in the production forecasting and enhance the interpretive capability of reservoir properties. Accordingly, the workflow evaluates consistency of reservoir simulation model and inverted seismic impedance, assisted by production history data, to close the loop between reservoir engineering and seismic domains. The methodology is evaluated in a complex, faulted, sandstone reservoir, the Norne benchmark field, where a significant reservoir behaviour understanding (about the static and dynamic reservoir properties) is obtained towards the quantitative integration of seismic impedance data. This leads to diagnosis of the reservoir flow simulation reliability and generation of an updated simulation model consistent with observed seismic and well production history data, as well as a calibrated petro-elastic model. Furthermore, as Norne Field is a benchmark case, this study can be considered to enrich the discussions over deterministic or probabilistic history matching studies.     

Intermediary LEO propagation including higher order zonal harmonics

Two new intermediary orbits of the artificial satellite problem are proposed. The analytical solutions include higher order effects of the geopotential, and are obtained by means of a torsion transformation applied to the quasi-Keplerian system resulting after the elimination of the parallax simplification, for the first intermediary, and after the elimination of the parallax and perigee simplifications, for the second one. The new intermediaries perform notably well for low Earth orbits propagation, are free from special functions, and result advantageous, both in accuracy and efficiency, when compared to the standard Cowell integration of the \(J_2\) problem, thus providing appealing alternatives for onboard, short-term, orbit propagation under limited computational resources.     

A New Solar Imaging System for Observing High-Speed Eruptions: <Emphasis Type="Italic">Solar Dynamics Doppler Imager</Emphasis> (SDDI)

A new solar imaging system was installed at Hida Observatory to observe the dynamics of flares and filament eruptions. The system (Solar Dynamics Doppler Imager; SDDI) takes full-disk solar images with a field of view of \(2520~\mbox{arcsec} \times 2520~\mbox{arcsec}\) at multiple wavelengths around the \(\mathrm{H}\alpha\) line at 6562 Å. Regular operation was started in May 2016, in which images at 73 wavelength positions spanning from \(\mathrm{H}\alpha -9~\mathring{\mathrm{A}}\) to \(\mathrm{H}\alpha +9~\mathring{\mathrm{A}}\) are obtained every 15 seconds. The large dynamic range of the line-of-sight velocity measurements (\({\pm}\,400~\mbox{km}\,\mbox{s}^{-1}\)) allows us to determine the real motions of erupting filaments in 3D space. It is expected that SDDI provides unprecedented datasets to study the relation between the kinematics of filament eruptions and coronal mass ejections (CME), and to contribute to the real-time prediction of the occurrence of CMEs that cause a significant impact on the space environment of the Earth.     

Downscaling ability of one-way nested regional climate models: the Big-Brother Experiment

A methodology is developed for testing the downscaling ability of nested regional climate models (RCMs). The proposed methodology, nick-named the Big-Brother Experiment (BBE), is based on a "perfect-prognosis" approach and hence does not suffer from model errors nor from limitations in observed climatologies. The BBE consists in first establishing a reference climate by performing a large-domain high-resolution RCM simulation: this simulation is called the Big Brother. This reference simulation is then degraded by filtering short scales that are unresolved in today's global objective analyses (OA) and/or global climate models (GCMs) when integrated for climate projections. This filtered reference is then used to drive the same nested RCM (called the Little Brother), integrated at the same high-resolution as the Big Brother, but over a smaller domain that is embedded in the Big-Brother domain. The climate statistics of the Little Brother are then compared with those of the Big Brother over the Little-Brother domain. Differences can thus be attributed unambiguously to errors associated with the nesting and downscaling technique, and not to model errors nor to observation limitations. The results of the BBE applied to a one-winter-month simulation over eastern North America at 45-km grid-spacing resolution show that the one-way nesting strategy has skill in downscaling large-scale information to the regional scales. The time mean and variability of fine-scale features in a number of fields, such as sea level pressure, 975-hPa temperature and precipitation are successfully reproduced, particularly over regions where small-scale surface forcings are strong. Over other regions such as the ocean and away from the surface, the small-scale reproducibility is more difficult to achieve.     

Agrometeorological Research and Applications Needed to Prepare Agriculture and Forestry to 21st Century Climate Change

The adaptation of agriculture and forestry to the climate of the twenty-first century supposes that research projects will be conducted cooperatively between meteorologists, agronomists, soil scientists, hydrologists, and modellers. To prepare for it, it is appropriate first of all to study the variations in the climate of the past using extensive, homogenised series of meteorological or phenological data. General circulation models constitute the basic tool in order to predict future changes in climate. They will be improved, and the regionalisation techniques used for downscaling climate predictions will also be made more efficient. Crop simulation models using input data from the general circulation models applied at the regional level ought to be the favoured tools to allow the extrapolation of the major trends on yield, consumption of water, fertilisers, pesticides, the environment and rural development. For this, they have to be validated according to the available agronomical data, particularly the available phenological series on cultivated crops. In addition, climate change would have impact on crop diseases and parasites, as well as on weeds. Very few studies have been carried out in this field. It is also necessary to quantify in a more accurate way the stocks and fluxes of carbon in large forest ecosystems, simulate their future, and assess the vulnerability of the various forest species to a change in climate. This is all the more important in that some propagate species choices must be made in the course of the next ten years in plantations which will experience changed climate. More broadly speaking, we shall have not only to try hard to research new agricultural and forestry practices which will reduce greenhouse gas emissions or promote the storage of carbon, but it will also be indispensable to prepare the adaptation of numerous rural communities for the climate change (with special reference to least developed countries in tropical areas, where malnutrition is a common threat). This can be accomplished with a series of new environmental management practices suited to the new climatic order.     

Recent changes in estuarine benthic and suprabenthic communities resulting from the development of harbour infrastructure

Using a Before/During/After sampling protocol, the effects of the Le Havre harbour extension, which was started at the end of 2001, on the macrobenthic and suprabenthic communities in the eastern Bay of Seine (English Channel) were examined. As the construction phase has not yet been completed, the results presented here reflect only the data collected before and during the operations (September 2000 and 2002 for benthos sampling and March 2001, September 2001, October 2002 and March 2003 for suprabenthos sampling). Although bio-sedimentary changes did occur at the mouth of the Seine river, an analysis of benthic assemblages reveals that the dredging and construction operations do not seem to have influenced assemblage structure or the spatial distribution of organisms. Comparisons of the suprabenthic assemblages at each sampling date indicate that seasonal dynamics was mainly responsible for determining species distribution. We conclude that, 1 year into the harbour management plan, the observed changes in benthic and suprabenthic assemblage abundance do not exceed the range of spatial variability that exists naturally in the Seine estuary. Despite this compensatory actions designed to protect the aquatic habitats and to preserve a sustainable and healthy ecosystem have been added to the infrastructure development plan.     

Research on the HIP 18856 binary system

The results of a study on the binary HIP 18856 and construction of its orbit are presented.New observational data were obtained at the BTA of SAO RAS in 2007-2019.Earlier,Cvetkovic et al.constructed the orbit for this system.However,it is based on six measurements,which cover a small part of the orbit.The positional parameters of the ESA astrometric satellite Hipparcos published speckle interferometric data(Mason et al.,Balega et al.,Horch et al.)and new ones were used in this study.Based on the new orbital parameters,the mass sum was calculated and the physical parameters of the components were found.The obtained orbital and fundamental parameters were compared with the data from the study by Cvetkovic et al..The comparison shows that the new orbital solution is better than the old one,since it fits new observational data accurately.Also based on a qualitative evaluation performed by Worley&Heintz,the new orbit was classified as"reliable",which means data cover more than half of the orbit with sufficient quantities of residuals of measurements.     

Scapolite stoichiometry

Over the range Ca/(Ca + Na) from zero to 0.75, scapolites vary linearly between Na₄Al₃Si₉O₂₄Cl and NaCa₃Al₅Si₇O₂₄CO₃, by means of a coupled replacement of Na₃Si₂Cl by Ca₃Al₂CO₃. Ca includes minor Sr, Na includes K, and CO₃ may include substantial SO₄. From Ca/(Ca + Na) = 0.75 to 1.00, variation is between NaCa₃Al₅Si₇O₂₄CO₃ and Ca₄Al₆Si₆O₂₄CO₃, by means of a coupled replacement of NaSi by CaAl, as in plagioclase. Anion substitution is complete at the 0.75 point. Recalculation of scapolite analyses on the basis of Al + Si atoms = 12.0, as suggested by computed unit cell contents, offers a reasonable basis for normalization of atomic proportions. On this basis, Ca + Sr + Na + K + Fe atoms total very close to 4.0. New limits on the minor element content of scapolite are proposed. In view of the inflection at 0.75, subdivision of the scapolites at Ca/(Ca + Na) ratios of 0.25, 0.5, and 0.75 seems more logical than the 0.2, 0.5, and 0.8 limits used hitherto for marialite, dipyre, mizzonite, and meionite.