Modelling and observations of photospheric magnetic helicity

Mounting observational evidence of the emergence of twisted magnetic flux tubes through the photosphere have now been published. Such flux tubes, formed by the solar dynamo and transported through the convection zone, eventually reach the solar atmosphere. Their accumulation in the solar corona leads to flares and coronal mass ejections. Since reconnections occur during the evolution of the flux tubes, the concepts of twist and magnetic stress become inappropriate. Magnetic helicity, as a well preserved quantity, in particular in plasma with high magnetic Reynolds number, is a more suitable physical quantity to use, even if reconnection is involved.     

Are small-scale field-aligned currents and magnetosheath-like particle precipitation signatures of the same low-altitude cusp?

We examined some 75 observations from the low-altitude Earth orbiting DMSP, Ørsted and CHAMP satellites which were taken in the region of the nominal cusp. Our objective was to determine whether the actually observed cusp locations as inferred from magnetosheath-like particle precipitation (“particle cusp”) and intense small-scale magnetic field variations (“current cusp”), respectively, were identical and were consistent with the statistically expected latitude of the cusp derived from a huge number of charged particle spectrograms (“statistical cusp”).     

A high-performance ground-based prototype of horn-type sequential vegetable production facility for life support system in space

Vegetable cultivation plays a crucial role in dietary supplements and psychosocial benefits of the crew during manned space flight. Here we developed a ground-based prototype of horn-type sequential vegetable production facility, named Horn-type Producer (HTP), which was capable of simulating the microgravity effect and the continuous cultivation of leaf–vegetables on root modules. The growth chamber of the facility had a volume of 0.12 m³, characterized by a three-stage space expansion with plant growth. The planting surface of 0.154 m² was comprised of six ring-shaped root modules with a fibrous ion-exchange resin substrate. Root modules were fastened to a central porous tube supplying water, and moved forward with plant growth. The total illuminated crop area of 0.567 m² was provided by a combination of red and white light emitting diodes on the internal surfaces. In tests with a 24-h photoperiod, the productivity of the HTP at 0.3 kW for lettuce achieved 254.3 g eatable biomass per week. Long-term operation of the HTP did not alter vegetable nutrition composition to any great extent. Furthermore, the efficiency of the HTP, based on the Q-criterion, was 7 × 10⁻⁴ g² m⁻³ J⁻¹. These results show that the HTP exhibited high productivity, stable quality, and good efficiency in the process of planting lettuce, indicative of an interesting design for space vegetable production.     

Sunspot numbers,interplanetary magnetic field,and cosmic ray intensity at earth: Nexus for the twentieth century

The pivotal role played by the interplanetary magnetic field (B) in modulating galactic cosmic ray (GCR) intensity in the heliosphere is described. We show that the inverse correlation observed by Forbush (1958) between GCRs and sunspot numbers (SSNs) is reflected in high correlation between SSNs and B (cc = 0.94). The SSN data are available since 1700 and the derived B data since 1835. The paleo-cosmic ray data are available for several millennia in the form of ¹⁰Be radionuclide sequestered in polar ice. The data of the ion chambers (ICs) at the Cheltenham–Fredericksburg–Yakutsk (CFY) sites are combined to create a data string for 1937–1988. In turn, these data are used to extend the measurements of the low energy GCR ions (>0.1 GeV) at balloon altitudes at high latitudes in Russia to 1937. These data are then correlated to B and the fit parameters are used to extend the low energy ion data to 1900, creating the instrumental era GCR time series for the twentieth century. The derived GCR time series is compared to ¹⁰Be measured at two sites in Greenland, namely Dye 3 and NGRIP for 1900–2000 to check the internal consistency of datasets for the long-term trend. We find that the annual mean rate (%) for 1965 at NGRIP is an outlier. We replace it with the mean of 1964 and 1965 rates and construct a new re-normalized time series at NGIP, improving the agreement with the derived instrumental era GCR time series for the twentieth century as well. This should encourage its use by heliophysics community for varied applications.     

A statistical study of C IV regions in 20 Oe-stars

In this paper, using the Gauss-Rotation model (GR model), we analyse the UV C IV resonance lines in the spectra of 20 Oe-stars of different spectral subtypes, in order to detect the structure of C IV region. We study the presence and behavior of absorption clouds and analyse their characteristics. From this analysis we can calculate the values of a group of physical parameters, such as the apparent rotational and radial velocities, the random velocities of the thermal motions of the ions, the Full Width at Half Maximum (FWHM), the optical depth, as well as the absorbed energy and the column density of the independent regions of matter, which produce the main and the satellite clouds of the studied spectral lines. Finally, we present the relations between these physical parameters and the spectral subtypes of the studied stars and we give our results about the structure of the C IV region in their atmosphere.     

Mapping lunar surface chemistry: New prospects with the Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS)

Surface chemistry of airless bodies in the solar system can be derived from remote X-ray spectral measurements from an orbiting spacecraft. X-rays from planetary surfaces are excited primarily by solar X-rays. Several experiments in the past have used this technique of X-ray fluorescence for deriving abundances of the major rock forming elements. The Chandrayaan-2 orbiter carries an X-ray fluorescence experiment named CLASS that is designed based on results from its predecessor C1XS flown on Chandrayaan-1. We discuss the new aspects of lunar science that can be potentially achieved with CLASS.     

Longitudinal variation of the equatorial ionosphere: Modeling and experimental results

We describe a new version of the Parameterized Regional Ionospheric Model (PARIM) which has been modified to include the longitudinal dependences. This model has been reconstructed using multidimensional Fourier series. To validate PARIM results, the South America maps of critical frequencies for the E (foE) and F (foF2) regions were compared with the values calculated by Sheffield Plasmasphere-Ionosphere Model (SUPIM) and IRI representations. PARIM presents very good results, the general characteristics of both regions, mainly the presence of the equatorial ionization anomaly, were well reproduced for equinoctial conditions of solar minimum and maximum. The values of foF2 and hmF2 recorded over Jicamarca (12°S; 77°W; dip lat. 1°N; mag. declination 0.3°) and sites of the conjugate point equatorial experiment (COPEX) campaign Boa Vista (2.8°N; 60.7°W; dip lat. 11.4°; mag. declination −13.1°), Cachimbo (9.5°S; 54.8°W; dip lat. −1.8°; mag. declination −15.5°), and Campo Grande (20.4°S; 54.6°W; dip lat. −11.1°; mag. declination −14.0°) have been used in this work. foF2 calculated by PARIM show good agreement with the observations, except during morning over Boa Vista and midnight-morning over Campo Grande. Some discrepancies were also found for the F-region peak height (hmF2) near the geomagnetic equator during times of F₃ layer occurrences. IRI has underestimated both foF2 and hmF2 over equatorial and low latitude sectors during evening-nighttimes, except for Jicamarca where foF2 values were overestimated.     

Sunspot activity and cosmic ray modulation at 1 a.u. for 1900–2013

The descent of sunspot cycle 23 to an unprecedented minimum of long duration in 2006–2009 led to a prolonged galactic cosmic ray (GCR) recovery to the highest level observed in the instrumental era for a variety of energetic charged particle species on Earth, over a wide range of rigidities. The remarkable GCR increase measured by several ground-based, balloon-borne, and detectors on a satellite is described and discussed. It is accompanied by a decrease in solar wind velocity and interplanetary magnetic field at 1 a.u., reaching the lowest values since measurements of the solar wind began in October 1963; the solar polar field strength (μT) measured at the Wilcox Solar Observatory (WSO) is also significantly reduced compared to prior cycles since the start of the program in 1976, the polar field in the northern hemisphere reversed in June 2012 and again in February 2014, that in the southern hemisphere reversed in July 2013. If updates of WSO data confirm the second reversal in northern solar hemisphere, it would pose a serious challenge to the Dynamo Theory. The long-term change in solar behavior may have begun in 1992, perhaps earlier. The physical underpinnings of these solar changes need to be understood and their effect on GCR modulation processes clarified. The study discusses the recent phenomena in the context of GCR modulation since 1900. These happenings affected our empirical predictions for the key parameters for the next two sunspot cycles (they may be progressively less active than sunspot cycle 24) but it enhanced support for our prediction that solar activity is descending into a Dalton-like grand minimum in the middle of the twentyfirst century, reducing the frequency of the coronal mass ejections; they determine the space weather affecting the quality of life on Earth, radiation dose for hardware and human activities in space as well as the frequency of large Forbush decreases at 1 a.u.     

Earth observation from space – The issue of environmental sustainability

Remote sensing scientists work under assumptions that should not be taken for granted and should, therefore, be challenged. These assumptions include the following:1. Space, especially Low Earth Orbit (LEO), will always be available to governmental and commercial space entities that launch Earth remote sensing missions.2. Space launches are benign with respect to environmental impacts.3. Minimization of Type 1 error, which provides increased confidence in the experimental outcome, is the best way to assess the significance of environmental change.4. Large-area remote sensing investigations, i.e. national, continental, global studies, are best done from space.5. National space missions should trump international, cooperative space missions to ensure national control and distribution of the data products.At best, all of these points are arguable, and in some cases, they're wrong. Development of observational space systems that are compatible with sustainability principles should be a primary concern when Earth remote sensing space systems are envisioned, designed, and launched. The discussion is based on the hypothesis that reducing the environmental impacts of the data acquisition step, which is at the very beginning of the information stream leading to decision and action, will enhance coherence in the information stream and strengthen the capacity of measurement processes to meet their stated functional goal, i.e. sustainable management of Earth resources. We suggest that unconventional points of view should be adopted and when appropriate, remedial measures considered that could help to reduce the environmental footprint of space remote sensing and of Earth observation and monitoring systems in general. This article discusses these five assumptions in the context of sustainable management of Earth's resources. Taking each assumption in turn, we find the following:(1) Space debris may limit access to Low Earth Orbit over the next decades.(2) Relatively speaking, given that they're rare event, space launches may be benign, but study is merited on upper stratospheric and exospheric layers given the chemical activity associated with rocket combustion by-products.(3) Minimization of Type II error should be considered in situations where minimization of Type I error greatly hampers or precludes our ability to correct the environmental condition being studied.(4) In certain situations, airborne collects may be less expensive and more environmentally benign, and comparative studies should be done to determine which path is wisest.(5) International cooperation and data sharing will reduce instrument and launch costs and mission redundancy. Given fiscal concerns of most of the major space agencies – e.g. NASA, ESA, CNES – it seems prudent to combine resources.