Region 1 Research Articles

Magnetosphere–Ionosphere Conjugate Harang Discontinuity and Sub-Auroral Polarization Streams (SAPS) Phenomena Observed by Multipoint Satellites

It is well understood that near midnight, the Harang Discontinuity separates the auroral duskside eastward electrojet (EEJ) and dawnside westward electrojet (WEJ) and associated plasma flows driven by enhanced magnetospheric convections via Magnetosphere–Ionosphere (M–I) coupling. There are conflicting reports regarding the significance of Region1 (R1) and R2 currents and the enhancement of Sub-Auroral Polarization Streams (SAPS) in the Harang region. We investigate the M–I conjugate Harang and SAPS phenomena using multipoint satellite observations. Results show the inner-magnetosphere (1) Harang region at midnight (between the plasmapause and the closed/open field-line boundary) with (2) a strong SAPS electric field (EX ≈ 30 mV/m; in magnitude) in a fast-time voltage generator (VGFT) near the plasmapause and the topside ionosphere (3) Harang Discontinuity (where R1 and R2 currents flow along) with (4) an enhanced SAPS flow (~1800 m/s) in the underlying VGFT system (requiring no R2 currents). From these (1–4) findings we conclude (i) the significance of both R1 and R2 currents in the observed M–I conjugate Harang phenomenon’s development, (ii) the different development of the reversing EEJ–WEJ compared to the regular auroral EEJ and WEJ in the topside ionosphere R1–R2 system, and (iii) the R2 currents’ absence in the enhanced SAPS flow newly formed in the VGFT system.

The HSV-1 pUL37 protein promotes cell invasion by regulating the kinesin-1 motor

Neurotropic alphaherpesviruses, including herpes simplex virus type 1 (HSV-1), recruit microtubule motor proteins to invade cells. The incoming viral particle traffics to nuclei in a two-step process. First, the particle uses the dynein-dynactin motor to sustain transport to the centrosome. In neurons, this step is responsible for long-distance retrograde axonal transport and is an important component of the neuroinvasive property shared by these viruses. Second, a kinesin-dependent mechanism redirects the particle from the centrosome to the nucleus. We have reported that the kinesin motor used during the second step of invasion is assimilated into nascent virions during the previous round of infection. Here, we report that the HSV-1 pUL37 tegument protein suppresses the assimilated kinesin-1 motor during retrograde axonal transport. Region 2 (R2) of pUL37 was required for suppression and functioned independently of the autoinhibitory mechanism native to kinesin-1. Furthermore, the motor domain and proximal coiled coil of kinesin-1 were sufficient for HSV-1 assimilation, pUL37 suppression, and nuclear trafficking. pUL37 localized to the centrosome, the site of assimilated kinesin-1 activation during infection, when expressed in cells in the absence of other viral proteins; however, pUL37 did not suppress kinesin-1 in this context. These results indicate that the pUL37 tegument protein spatially and temporally regulates kinesin-1 via the amino-terminal motor region in the context of the incoming viral particle.

Phenotypic characterization for milk traits in crossbred cattle population from the state of Norte de Santander

Crossbred cattle are used in dual-purpose systems to obtain meat and milk, becoming one of Colombia's systems with the greatest presence. However, studies characterizing productive variables in crossbred individuals are scarce, making it pertinent to conduct analyses evaluating their potential. The objective of this study was to phenotypically characterize a population of crossbred cattle from the state of Norte de Santander (Colombia) in terms of milk traits. Up to a maximum of 4 controls per female was obtained, and information on milk yield (MY), fat percentage (FP), protein percentage (PP), and somatic cell count (SCC) of first parity crossbred females was evaluated. The information was filtered and analyzed with the R program. The mean, standard deviation, and general variation coefficient were calculated for each trait and the means and deviations by non-genetic categorical factors. For the numeric factors, graphs of trends related to the response variables were made. Multiple correspondence analysis was performed, and the standardized residual values were estimated to recognize associations between levels of non-genetic factors and each trait. Mean values for controls were: 3.06±1.40 kg/day (MY), 3.21±0.40% (PP), 3.32±0.77% (FP), and 357±256x103 cells/ml (SCC). The non-genetic factors that showed the most significance were the pasture type, the control season, and the region. Thus, MY from 1.00 to 2.00 kg is associated with the levels of region 1 (R1) and summer 1 (S1), MY from 2.10 to 3.99 kg with region 2 (R2), group 1 (G1) and winter 1 (W1), MY from 4.00 to 8.30 kg with R1, group 3 (G3) and W1, PP from 2.45 to 2.99% there was association with G1, PP from 3.00 to 3.40% with group 2 (G2), PP from 3.41 to 6.04% with G3, FP of 1.94 to 3.00% is associated with R1, G3, S1, and S2, FP of 3.01 to 4.00% with R2, G1 and W1, FP from 4 to 4.82 % with region 3 (R3), G2, and S1, SCC from 8.00 to 100x103 cells/ml is associated with R1, R3, and S1, SCC of 101 to 499x103 cells/ml with R2, G1, and W1. Finally, SCC of 500 to 888x103 cells/ml is associated with R2 and W1. A variation of medium to high magnitude of the traits evaluated within the population was evidenced, revealing that no standards that allow unifying the management of animals within herds, which can affect the efficiency of dual-purpose systems.

On the Relationship Between Regions of Large‐Scale Field‐Aligned Currents and Regions of Plateau in Plasma Pressure Observed in the Equatorial Plane of the Earth's Magnetosphere

AbstractSince the discovery of the large‐scale field‐aligned currents it is widely acknowledged that gaps exist between the Region 1 (R1) and Region 2 (R2) currents in which the current values are relatively small as compared to neighboring regions. Assuming that the field‐aligned currents are generated by plasma pressure gradients, we analyzed data collected by the THEMIS satellites between 2007 and 2011 to identify regions with very low plasma pressure gradients (pressure plateaus), which could be responsible for the appearance of these gaps. It was found that the pressure profiles with low radial gradients are typically located between 8 and 10 Radii around the Earth. Projections of pressure plateau regions onto ionospheric altitudes, for both individual events and on a statistical basis, coincide with the locations of gaps between Iijima and Potemra field‐aligned currents. The role played by identified pressure plateaus in shaping the pattern of large‐scale field‐aligned currents is discussed.

Energetic Electron Flux Dropouts Measured by ELFIN in the Ionospheric Projection of the Plasma Sheet

AbstractLow‐altitude observations of magnetospheric particles provide a unique opportunity for remote probing of the magnetospheric and plasma states during active times. We present the first statistical analysis of a specific pattern in such observations, energetic electron flux dropouts in the low‐altitude projection of the plasma sheet. Using 3.5 years of data from the ELFIN CubeSats we report the occurrence distribution of 145 energetic electron flux dropout events and identify characteristics, including their prevalence in the dusk and premidnight sectors, their association with substorms and enhanced auroral activities, and their correlation with the region‐1 (R1) field‐aligned current region. We also investigate three representative dropout events which benefit from satellite conjunctions between ELFIN, GOES, and THEMIS, to better understand the magnetospheric drivers and magnetic field conditions that lead to such dropouts as viewed by ELFIN. One class of dropouts may be associated with magnetic field mapping distortions due to local enhancements and thinning of cross‐tail current sheets and amplification of R1 field‐aligned currents. The other class may be associated with the increase in perpendicular anisotropy of magnetospheric electrons due to magnetic field dipolarizations near premidnight. These plasma sheet flux dropouts at ELFIN provide a valuable tool for refining magnetospheric models, thereby improving the accuracy of field‐line mapping during substorms.

Influence of the Polar Electrojet on Field‐Aligned Current Estimates From Single Satellite Magnetic Field Measurements

AbstractThe high‐resolution magnetic field measurements from European Space Agency's (ESA’s) Swarm satellite constellation provide a good opportunity for revisiting the mean properties of ionospheric currents. Among the Swarm Level‐2 data products, provided by European Space Agency, are field‐aligned current (FAC) estimates based on single‐spacecraft (single‐SC) and dual‐spacecraft (dual‐SC) solutions. For the more reliable dual‐SC approach only magnetic signatures from currents flowing through the integration loop are considered, while in the case of single‐SC FAC estimates the magnetic effects of all remote current systems contribute to the results. A direct comparison between the two FAC products at auroral latitudes reveals that the single‐SC estimates systematically overestimate the current density of region 2 (R2) FACs by about 15%, while underestimates the region 1 (R1) FACs by about 10%. The differences between the two FAC products appear closely related to the location and direction of the horizontal polar electrojet (PEJ) at auroral latitudes. A direct comparison of these two current systems suggests an influence of the PEJ induced magnetic field on the solutions from single‐SC FACs. Our preferred explanation is the effect of a partial diversion of the anti‐sunward flowing electrojet current into the polar cap region. The current deflection angle increases toward the pole. The B‐field of such a current flow geometry can explain the single‐SC differences. It is consistent with the general picture of the high‐latitude Hall current vortices. As a side aspect, we found that the mean PEJ intensities are almost identical in both hemispheres, but the latitudes of the current peaks differ between the two hemispheres in the morning/afternoon sectors by about 1°. The reason for this difference is not clear.

The Relationship Between Vertical Facial Type and Maxillary Anterior Alveolar Angle in Adults Using Cone-Beam Computed Tomography.

BackgroundCone-beam computed tomography (CBCT) imaging provides detailed and thorough information about the dentofacial complex. However, not all aspects have been yet explored among different types of malocclusion. The maxillary anterior alveolus is one of the components of the maxillary bone which affects the upper lip position and the esthetics of the smile. The inclination of this alveolus may vary between the different vertical growth patterns of patients who may seek orthodontic treatment. The objective of this study was to investigate possible differences in maxillary anterior alveolar angle (MAAA) among orthodontically untreated adults with different vertical facial types in a Syrian sample.MethodsCBCT images of 84 orthodontically untreated adult patients were included. Three groups of vertical facial type (n=28 for each group; 14 males, 14 females) were created using disproportionate multi-stratified random sampling. CBCT-derived lateral cephalograms were used to categorize the patients into three groups. Measurements were made at three regions (region 1 (R1), region 2 (R2), and region 3 (R3)), located in the maxillary anterior alveolar bone using OnDemand3D™ software (Cypermed Inc., Seoul, South Korea).ResultsNo significant differences in the mean MAAA were detected between females and males for the three measured regions in all groups. Analysis of variance showed significant inter-group differences in the MAAA (p<0.05) for all measured regions. The hyperdivergent facial type group had the greatest MAAA mean value of 68.72° (± 6.01), 67.30° (± 4.15), and 68.01° (± 5.12) at R1 in the female, male, and the entire sample of both sexes respectively. Whereas the hypodivergent facial type group had the least mean MAAA values of 58.47° (± 5.34) at R3, 59.83° (± 6.23) at R2, and 59.23° (± 5.75) at R3 in the female, male, and the entire sample of both sexes respectively.ConclusionsThe maxillary anterior alveolar bone was more buccally inclined in the hypodivergent facial type. The MAA bone inclination did not differ between females and males in the same vertical facial type group.

Newly Formed Dawnside, Duskside, and Nightside Subauroral Flows Developed During Magnetically Active Times

AbstractWe study the newly formed (with an upper limit of ∼101 min) subauroral flows in the topside ionosphere. These include the dawnside subauroral flows observed at ∼5–6 magnetic local time (MLT), the duskside sub‐auroral polarization streams (SAPS) at ∼15 MLT, and the nightside sub‐auroral ion drifts (SAID) at ∼19–20 MLT. We employ the same types of observations for investigating the various underlying magnetospheric processes related to the development of the newly formed subauroral flows. These processes include (a) the stretching of magnetic field lines (leading to plasma density dropouts) due to the unfolding magnetotail reconnection, (b) the dawnside and nightside diversions of the magnetotail‐reconnection—related earthward plasma flows, (c) the ongoing particle injections, and (d) the trapping of ring current protons at subauroral and auroral latitudes. Based on these processes (a–d), we found strong similarities in the development of the newly formed dawnside and duskside/nightside subauroral flows investigated. At the dawnside plasmapause in the inner magnetosphere equatorial plane, the outward and duskward electric (E) field components provide observational evidence that the newly formed dawnside rapid narrow subauroral flows were SAID developing in the dawn sector. Evidence shows that the newly formed dawnside broad subauroral flow channel was associated with upward Region 2 (R2) field‐aligned currents (FACs) and equatorward subauroral polarization E field, and thus, was the dawnside equivalent of the duskside SAPS associated with downward R2 FACs and poleward subauroral polarization E field. Further evidence includes the inner magnetosphere observations of the hot zone both on the dusk/nightside and on the dawnside.

Projections of the characteristics and probability of spatially concurrent hydrological drought in a cascade reservoirs area under CMIP6

Improving the understanding of the future hydrological drought variability in cascade reservoirs area is indispensable for water resource management, especially in the context of changing climate. This study aims to investigate the hydrological drought variations in the upper Yellow River Basin (UYRB) during 2021–2100 employing the latest Coupled Model Intercomparison Project Phase 6 (CMIP6) datasets. The study area is divided into three sub-regions based on the location of the two large reservoirs, i.e., Region 1 (R1) and Region 2 (R2) have reservoirs while Region 3 (R3) has none. The meteorological data from 10 CMIP6 models are downscaled by utilizing the bias-corrected spatial disaggregation (BCSD) method and then used to force the improved abcd hydrological model for future monthly runoff simulations. The changes in severity, duration, and frequency of drought events in three sub-regions under two future climate scenarios (SSP2-4.5 and SSP5-8.5) relative to the historical period are identified. Then, the copula function is applied to explore the changes in probabilities of spatially concurrent drought for different cases in the future. The most likely combination of drought intensity for R1 and R2 corresponding to 10-years conditional return periods is estimated to demonstrate changes in drought risks across the reservoir areas. Results show that the drought frequency of R2 and R3 is expected to increase in spring and summer, and the drought events are projected to have a shorter duration and lower severity overall under two scenarios. Additionally, the spring probabilities of concurrent drought for different cases are expected to increase in the near future (increase by 1.9%–19.3%), but only increase in R2&R3 case in the far future. It is noted that although the drought probabilities will decrease in winter, R1 and R2 are expected to experience more severe drought when drought occurs in R3. The findings are helpful to improve the understanding of future hydrological drought risk in the UYRB and provide guidelines for making adaptation strategies to climate change.

Statistical Analysis of Bifurcating Region 2 Field-Aligned Currents Using AMPERE

We present a statistical analysis of the occurrence of bifurcations of the Region 2 (R2) Field-Aligned Current (FAC) region, observed by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). Previously, these have been shown to occur as the polar cap contracts after substorm onset, the beginning of the growth phase. During this phase both the Region 1 (R1) and R2 currents move equatorwards as the polar cap expands. Following onset, the R1 FAC region contracts polewards but the R2 FAC continues to expand equatorwards before eventually fading. At the same time, a new R2 FAC develops equatorwards of the R1 FAC. We have proposed that the bifurcated FACs formed during substorms are associated with plasma injections from the magnetotail into the inner magnetosphere, and that they might be the FAC signature associated with Sub-Auroral Polarization Streams (SAPS). We investigate the seasonal dependence of the occurrence of bifurcations from 2010 to 2016, determining whether they occur predominantly at dawn or dusk. Region 2 Bifurcations (R2Bs) are observed most frequently in the summer hemisphere and at dusk, and we discuss the possible influence of ionospheric conductance. We also discuss a newly discovered UT dependence of the R2B occurrences between 2011 and 2014. This dependence is characterized by broad peaks in occurrence near 09 and 21 UT in both hemispheres. Reasons for such a preference in occurrence are explored.

GIỐNG ỐC CẠN DIORYX BENSON, 1859 (GASTROPODA: ALYCAEIDAE): DẪN LIỆU TẠI VIỆT NAM VÀ DANH SÁCH LOÀI CẬP NHẬT TRÊN THẾ GIỚI

The land area of Vietnam is composed of a large variety of undisturbed habitats, such as high mountainous areas, forests over limestone, limestone karsts, and especially the Truong Son mountain range. Therefore, Vietnam is expected to have a high species diversity, especially for the terrestrial snails. Species of Dioryx have been recognised as occurring from the southeastern Himalayan region to Taiwan (China) in the east, and down to the northern part of the Malay Peninsula. This genus is characterised by shell small to medium, globose; protoconch smooth, not spirally striated; Region 1 (R1) usually very finely reticulated due to fine radial ribs and fine spiral striation, or smooth; R2 short to long, usually without ribs. The Vietnamese members of the genus Dioryx are reviewed, and a checklist of all Dioryx species is provided. Eight species are recognised from Vietnam, in which, seven species were recorded from the Northern and North Central, and one species (Dioryx cochinensis) from the Southern.

#63: Antibodies to Peptides Representing Plasmodium falciparum Circumsporozoite Protein Reflect Acquisition of Naturally Acquired Immunity in Malian Adults and Children

Abstract Background An effective vaccine against Plasmodium falciparum, the most common and deadly cause of malaria, is a global priority. Circumsporozoite protein (CSP) is a major P. falciparum vaccine target. Previously recognized CSP epitopes include the immunodominant NANP repeat region, the conserved junction between Region 1 (R1) and the NANP repeats, and the polymorphic Th2R and Th3R in the C-terminus. RTS,S, the most advanced vaccine to date, contains 19 NANP repeats and the C-terminus from the 3D7 parasite clone. CSP-specific monoclonal antibodies to the R1-NANP junctional region showed potent neutralizing activity in vitro and in vivo and are therefore under development for immunoprophylaxis. However, little is known about naturally acquired humoral immunity to precise and diverse epitopes along the CSP sequence, especially in the R1-NANP junctional region. Our goal was to use novel high-throughput tools to examine immunity to diverse CSP epitopes. Methods We probed sera from 10 adults and 10 children from Bandiagara, Mali, a region with intense, seasonal malaria transmission, on a diversity-reflecting peptide microarray. This microarray included 73 CSP variants from reference genomes and field-derived genomic data represented as 16 amino acid (aa) peptides with 12 aa overlap. We used a sliding window-based average smoothing procedure to determine log2 transformed signal intensities (SI) at each aa position. SI and serorecognition, defined as SI &amp;gt;2.5 standard deviations above the mean SI of malaria-naïve controls, were compared. We used the Wilcoxon rank-sum test for comparisons between adults and children and the Wilcoxon signed-rank test for matched comparisons of children over the malaria season, with the Benjamini-Hochberg procedure to control the false discovery rate. Results Adult sera recognized more variants than children at 313 of the 401 positions along CSP, including areas of the R1-NANP junctional region, the NANP repeat region, and the C-terminal Th2R and Th3R epitopes. Adults had higher SI than children to variants in known epitopes, including the R1-NANP junctional region and NANP, but not to a large portion of the 3D7 sequence of Th2R. Across the malaria season, children did not recognize significantly more variants at any one position. However, children had higher SI mid-season when compared with pre-season at a few small epitopes in the R1-NANP junctional region and Th2R. No significant differences existed between SI at any position when comparing post- to mid- or pre-season. Conclusions We identified precise CSP epitopes where serologic responses differed between adults and children and in children over a malaria season in Bandiagara. Adults showed responses to more variants and higher antibody responses at the R1-NANP junctional region and the NANP repeat region, but not to the 3D7 variant sequence in the Th2R epitope, which is included in RTS,S. Children acquired some short-lived immunity to the R1-NANP junctional region and a Th2R epitope during the season but not the NANP repeat region. Our limitations included a small sample size. Next steps include differentiation of immunodominant from protective responses in a larger study with longitudinal infection surveillance data.

Early main-phase electrodynamics of the ring current inferred from DMSP

This paper exploits capabilities implicit in DMSP plasma and field data through which users may infer local IGRF magnetic fields (B→0), as well as components of magnetic perturbations (δB→⊥) and plasma drift (V→⊥) vectors perpendicular toB→0. We use relations between V→⊥ andδB→⊥, associated with Region 2 (R-2) field-aligned currents (FACs), consistent with Faraday's law, to determine Alfvénic reflection coefficients (α). Early main-phase measurements from three DMSP satellites, F16, F17 and F18 during the 17 March 2015 storm confirm the predicted V→⊥ andδB→⊥relationships. Data also show that high-latitude limits of R-2 FACs lie close to the equatorward boundaries of precipitating auroral electrons. Measurable fluxes of down-coming, ring-current ions are restricted to the vicinity of this auroral boundary. It thus remains an open question as to what particle population is responsible for carrying the downward FACs (j||) and Poynting fluxes (S||), inferred fromδB→⊥measurements acquired over the full latitudinal ranges of storm-time R-2.

Substorm Current Wedge: Energy Conversion and Current Diversion

AbstractUsing a magnetohydrodynamic simulation of magnetotail reconnection, flow bursts, and dipolarization, we further investigate the current diversion and energy flow and conversion associated with the substorm current wedge (SCW) or smaller‐scale wedgelets. Current diversion into both Region 1 (R1) and Region 2 (R2) sense systems is found to happen inside (that is, closer to the center of the flow burst) and equatorward of the R1 and R2 type field‐aligned currents. In contrast to earlier investigations the current diversion takes place in dipolarized fields extending all the way toward the equatorial plane. An additional FAC system with the signature of Region 0 (R0) (same sense as R2) is found at higher latitudes in taillike fields. The diversion into this system takes place in layers equatorward of the R0 currents but outside the equatorial plane. Whereas the diversion into R1 and R2 systems is pressure gradient dominated, the diversion into the R0 system is inertia dominated and may persist only during flow burst activity. While azimuthally diverging flows near the dipole contribute to the buildup of R1 and R2 systems, converging flows at larger distance contribute to the buildup of R0 and R1 systems. In contrast to the current diversion regions inside the current wedge, generator regions are found on the outside of the wedge, similar to earlier results. Within the tail domain covered, these regions are overpowered by load regions, such that additional generator regions must be expected closer to Earth, not covered by the present simulation.

Spatial and Temporal Evolution of Different‐Scale Ionospheric Irregularities in Central and East Siberia During the 27–28 May 2017 Geomagnetic Storm

AbstractWe present a multi‐instrumental study of ionospheric irregularities of different scales (from tens of centimeters to few kilometers) observed over the Central and East Siberia, Russia, during a moderate‐to‐strong geomagnetic storm on 27–28 May 2017. From high‐frequency (HF) and ultrahigh‐frequency (UHF) radar data, we observed an intense auroral backscatter developed right after the initial phase of the geomagnetic storm. Additionally, we examined variations of Global Positioning System (GPS)‐based ROT (rate of TEC changes, where TEC is total electron content) for available GPS receivers in the region. Ionosondes, HF, and UHF radar data exhibited a presence of intense multi‐scale ionospheric irregularities. We revealed a correlation between different‐scale Auroral/Farley‐Buneman ionospheric irregularities of the E layer during the geomagnetic storm. The combined analysis showed that an area of intense irregularities is well connected and located slightly equatorward to field‐aligned currents (FACs) and auroral oval at different stages of the geomagnetic storm. An increase and equatorward displacement of Region 1 (R1)/Region 2 (R2) FACs leads to appearance and equatorward expansion of ionospheric irregularities. During downward (upward) R1 FAC and upward (downward) R2 FAC, the eastward and upward (westward and downward) E × B drift of ionospheric irregularities occurred. Simultaneous disappearance of UHF/HF auroral backscatter and GPS ROT decrease occurred during a prolonged near noon reversal of R1 and R2 FAC directions that accompanied by R1/R2 FAC degradation and disappearance of high‐energy auroral precipitation.

AMPERE polar cap boundaries

Abstract. The high-latitude atmosphere is a dynamic region with processes that respond to forcing from the Sun, magnetosphere, neutral atmosphere, and ionosphere. Historically, the dominance of magnetosphere–ionosphere interactions has motivated upper atmospheric studies to use magnetic coordinates when examining magnetosphere–ionosphere–thermosphere coupling processes. However, there are significant differences between the dominant interactions within the polar cap, auroral oval, and equatorward of the auroral oval. Organising data relative to these boundaries has been shown to improve climatological and statistical studies, but the process of doing so is complicated by the shifting nature of the auroral oval and the difficulty in measuring its poleward and equatorward boundaries. This study presents a new set of open–closed magnetic field line boundaries (OCBs) obtained from Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) magnetic perturbation data. AMPERE observations of field-aligned currents (FACs) are used to determine the location of the boundary between the Region 1 (R1) and Region 2 (R2) FAC systems. This current boundary is thought to typically lie a few degrees equatorward of the OCB, making it a good candidate for obtaining OCB locations. The AMPERE R1–R2 boundaries are compared to the Defense Meteorological Satellite Program Special Sensor J (DMSP SSJ) electron energy flux boundaries to test this hypothesis and determine the best estimate of the systematic offset between the R1–R2 boundary and the OCB as a function of magnetic local time. These calibrated boundaries, as well as OCBs obtained from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) observations, are validated using simultaneous observations of the convection reversal boundary measured by DMSP. The validation shows that the OCBs from IMAGE and AMPERE may be used together in statistical studies, providing the basis of a long-term data set that can be used to separate observations originating inside and outside of the polar cap.

Timber Use, Processing Capacity, and Capability within the USDA Forest Service, Rocky Mountain Region Timber-Processing Area

Abstract Over the past two decades, more than half a million acres of forested land has experienced extensive insect- and disease-caused tree mortality within the USDA Forest Service Rocky Mountain Region 2 (R2) of the National Forest System. To plan for timber harvest treatments needed to restore forest health, managers need information on forest product facility capacity and capability to profitably process timber of various size classes. To answer this need, the authors summarized timber harvest volumes by state and county group, identified facilities in the R2 area, quantified timber-processing capacities and size class capabilities, and analyzed the geographic variability of timber flows from county of harvest to mill. Results showed that nearly 285.5 million board feet Scribner of timber flowed from the study area to 101 processors throughout the R2 timber-processing area. Approximately 70 percent of annual milling capacity can profitably process trees ≧10 in. dbh, whereas just 8 percent can process timber &amp;lt;7 in. dbh. When planning forest-management activities, land managers should balance the need to remove small and/or dead trees with the local industry’s ability to profitably use that material.

Modes of (FACs) Variability and Their Hemispheric Asymmetry Revealed by Inverse and Assimilative Analysis of Iridium Magnetometer Data

AbstractWe determine the primary modes of field‐aligned current (FAC) variability and their hemispheric asymmetry by nonlinear regression analysis of a multiyear global data set of Iridium constellation engineering‐grade magnetometer data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment program. The spatial and temporal FAC variability associated with three major categories of solar wind drivers, (1) slow flow, (2) high‐speed streams (HSS), (3) transient flow related to coronal mass ejections (CMEs), and (4) a combination of these, is characterized as empirical orthogonal functions (EOFs) and their time‐varying amplitude. For the combined solar wind category, the order of the modes of variability are strengthening/weakening of (1) EOF1—all FACs; (2) EOF2—Region 2 (R2) FACs; and (3) EOF3—dayside/nightside FACs. The first two EOFs are associated with solar wind coupling; EOF3 is associated with the ecliptic components of the interplanetary magnetic field (IMF). We also find hemispheric asymmetry in FACs. Northern Hemisphere EOFs show clearer spatial features and higher correlation coefficients with solar wind drivers. The Northern Hemisphere also shows higher correlation coefficients in all seasons except winter. We find transient flow EOFs to be better correlated with solar wind drivers such as IMF Bz and coupling functions, while HSS EOFs are better correlated with solar wind plasma parameters. CME‐related transient flow EOFs also show R2 FAC variabilities that are not found in other separate wind drivers. Application of the EOF analysis to the Iridium magnetometer data shows significant promise for greater understanding of geoeffectiveness of solar wind interactions with geospace.

Diagnosing the Role of Alfvén Waves in Global Field‐Aligned Current System Dynamics During Southward IMF: Swarm Observations

AbstractField‐aligned currents (FACs) are a primary signature of magnetosphere‐ionosphere coupling (MIC). However, establishing FACs requires the propagation of Alfvén waves. Large‐scale quasi‐static FACs are well‐organized into large‐scale Region 1 (R1) and Region 2 (R2) systems during intervals of southward interplanetary magnetic field (IMF); however, the scale‐dependent spatiotemporal variability and related electrodynamics are less well understood. Using the electric and magnetic field data from Swarms A and C, we examine the role of Alfvén waves in MIC at a range of scales during two auroral crossings during southward IMF on May 16, 2016. Interspacecraft techniques reveal large amplitude small‐scale (10s km) non‐stationary magnetic fields inconsistent with a quasi‐static formulation. Cross‐phase techniques reveal a frequency‐dependent E/B ratio and E‐B phase difference consistent with an Alfvén wave interpretation, validated using the Lysak (1991, https://doi.org/10.1029/90JA02154) ionospheric Alfvén resonator model constrained by inferred local Swarm plasma mass density. Local large amplitude E and B fields indicate the importance of Alfvénic energy transport at small scales. Evidence for Poynting flux concentration at the boundary between large‐scale upward and downward FACs is also presented. Our results suggest that cross‐scale FAC characteristics can be explained by a single Alfvén wave paradigm: quasi‐static large‐scale FACs representing the ω → 0 limit of a broader continuum of spatial scales associated with MIC. Future work should assess in more detail the energetic significance of small scales and the potential localization of large amplitude small‐scale disturbances at large scale FAC boundaries and assess related scale‐dependent MIC including Alfvénic ionospheric feedback.

Dependence of the Equatorial Electrojet on Auroral Activity and In Situ Solar Insulation

AbstractBy using 10 years of Challenging Minisatellite Payload satellite observations, we investigate the average conditions of the interplanetary magnetic field (IMF) prevailing during the westward counter equatorial electrojet (CEJ). Equally, we compared the average IMF conditions accompanying high‐latitude field‐aligned currents of the Region 1 (R1) and Region 2 (R2). It shows that both CEJ and high‐latitude field‐aligned currents events when R2 is greater than R1 tend to happen preferably during the northward turning of the IMF Bz and the substorm recovery phase. Sunlight has an important influence on the longitudinal distribution of the equatorial electrojet (EEJ), and the effect is opposite to the tidal electric field at region. The anticorrelation between cos (SZA) (solar zenith angle effect) average values during CEJ events and EEJ intensity is most prominent around June solstice. By using combined measurements from Challenging Minisatellite Payload and DMSP satellites, it is found that before the occurrence and in the initial phase of a subauroral polarization stream the EEJ gets enhanced, and after about 30 min it reduces in intensity. The CEJ occurrence rate more than doubles during subauroral polarization stream periods compared to normal conditions.