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By exploiting data from the STEREO/heliospheric imagers (HI) we extend a well‐established technique developed for coronal analysis by producing time‐elongation plots that reveal the nature of solar transient activity over a far more extensive region of the heliosphere than previously possible from coronagraph images. Despite the simplicity of these plots, their power in demonstrating how the plethora of ascending coronal features observed near the Sun evolve as they move antisunward is obvious. The time‐elongation profile of a transient tracked by HI can, moreover, be used to establish its angle out of the plane‐of‐the‐sky; an illustration of such analysis reveals coronal mass ejection material that can be clearly observed propagating out to distances beyond 1AU. This work confirms the value of the time‐elongation format in identifying/characterising transient activity in the inner heliosphere, whilst also validating the ability of HI to continuously monitor solar ejecta out to and beyond 1AU.

We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments on board NASA’s twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while following papers will present analyses of CME propagation through the entire HI fields of view. More specifically, in this paper we present distributions of the basic observational parameters – namely occurrence frequency, central position angle (PA) and PA span – derived from nearly 2000 detections of CMEs in the heliosphere by HI-1 on STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24 to the maximum of Cycle 24; STEREO-A analysis includes a further 158 CME detections from the descending phase of Cycle 24, by which time communication with STEREO-B had been lost. We compare heliospheric CME characteristics with properties of CMEs observed at coronal altitudes, and with sunspot number. As expected, heliospheric CME rates correlate with sunspot number, and are not inconsistent with coronal rates once instrumental factors/differences in cataloguing philosophy are considered. As well as being more abundant, heliospheric CMEs, like their coronal counterparts, tend to be wider during solar maximum. Our results confirm previous coronagraph analyses suggesting that CME launch sites do not simply migrate to higher latitudes with increasing solar activity. At solar minimum, CMEs tend to be launched from equatorial latitudes, while at maximum, CMEs appear to be launched over a much wider latitude range; this has implications for understanding the CME/solar source association. Our analysis provides some supporting evidence for the systematic dragging of CMEs to lower latitude as they propagate outwards.

The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalog listing the properties of 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ± 31 km s − 1 . Such a low mean value corresponds to the terminal speed of the slow solar wind rather than the speed of stream interfaces, which is typically intermediate between the slow and fast solar wind speeds ( ∼ 400 km s − 1 ). Using our fitting technique, we predicted the arrival time of each corotating density structure at different probes in the inner heliosphere. We find that our derived speeds are systematically lower by ∼ 100 km s − 1 than those measured in situ at the predicted impact times. Moreover, for cases when a stream interaction region is clearly detected in situ at the estimated impact time, we find that our derived speeds are lower than the speed of the stream interface measured in situ by an average of 55 km s − 1 at ST-A and 84 km s − 1 at STEREO-B (ST-B). We show that the speeds of the corotating density structures derived using our fitting technique track well the long-term variation of the radial speed of the slow solar wind during solar minimum years (2007 – 2008). Furthermore, we demonstrate that these features originate near the coronal neutral line that eventually becomes the heliospheric current sheet.

Soil organic carbon (SOC) is the largest terrestrial carbon (C) sink on Earth; this pool plays a critical role in ecosystem processes and climate change. Given the cost and time required to measure SOC, and particularly changes in SOC, many signatory nations to the United Nations Framework Convention on Climate Change report estimates of SOC stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specific models. In the United States, SOC in forests is monitored by the national forest inventory (NFI) conducted by the Forest Inventory and Analysis (FIA) program within the U.S. Department of Agriculture, Forest Service. The FIA program has been consistently measuring soil attributes as part of the NFI since 2001 and has amassed an extensive inventory of SOC in forest land in the conterminous United States and southeast and southcentral coastal Alaska. That said, the FIA program has been using country-specific predictions of SOC based, in part, upon a model using SOC estimates from the State Soil Geographic (STATSGO) database compiled by the Natural Resources Conservation Service. Estimates obtained from the STATSGO database are averages over large map units and are not expected to provide accurate estimates for specific locations, e.g., NFI plots. To improve the accuracy of SOC estimates in U.S. forests, NFI SOC observations were used for the first time to predict SOC density to a depth of 100 cm for all forested NFI plots. Incorporating soil-forming factors along with observations of SOC into a new estimation framework resulted in a 75% (48 ± 0.78 Mg/ha) increase in SOC densities nationally. This substantially increases the contribution of the SOC pool, from approximately 44% (17 Pg) of the total forest ecosystem C stocks to 56% (28 Pg), in the forest C budget of the United States.

In the United States (U.S.), the maintenance of forest cover is a legal mandate for federally managed forest lands. More broadly, reforestation following harvesting, recent or historic disturbances can enhance numerous carbon (C)-based ecosystem services and functions. These include production of woody biomass for forest products, and mitigation of atmospheric CO2 pollution and climate change by sequestering C into ecosystem pools where it can be stored for long timescales. Nonetheless, a range of assessments and analyses indicate that reforestation in the U.S. lags behind its potential, with the continuation of ecosystem services and functions at risk if reforestation is not increased. In this context, there is need for multiple independent analyses that quantify the role of reforestation in C sequestration, from ecosystems up to regional and national levels. Here, we describe the methods and report the findings of a large-scale data synthesis aimed at four objectives: (1) estimate C storage in major ecosystem pools in forest and other land cover types; (2) quantify sources of variation in ecosystem C pools; (3) compare the impacts of reforestation and afforestation on C pools; (4) assess whether these results hold or diverge across ecoregions. The results of our synthesis support four overarching inferences regarding reforestation and other land use impacts on C sequestration. First, in the bigger picture, soils are the dominant C pool in all ecosystems and land cover types in the U.S., and soil C pool sizes vary less by land cover than by other factors, such as spatial variation or soil wetness. Second, where historically cultivated lands are being reforested, topsoils are sequestering significant amounts of C, with the majority of reforested lands yet to reach their capacity relative to the potential indicated by natural forest soils. Third, the establishment of woody vegetation delivers immediate to multi-decadal C sequestration benefits in aboveground woody biomass and coarse woody debris pools, with two- to three-fold C sequestration benefits in biomass during the first several decades following planting. Fourth, opportunities to enhance C sequestration through reforestation vary among the ecoregions, according to current levels of planting, typical forest growth rates, and past land uses (especially cultivation). Altogether, our results suggest that an immediate, but phased and spatially targeted approach to reforestation can enhance C sequestration in forest biomass and soils in the U.S. for decades to centuries to come.

Agroforestry plantings and other trees intentionally established in rural and urban areas are emerging as innovative management options for addressing resource issues and achieving landscape-level goals. An understanding of the ecosystem services contributed by these and future plantings would provide critical information to policy and program developers, and a comprehensive inventory would contribute to estimating the cumulative effects of these plantings. Trees used in these practices are not explicitly inventoried by the primary national forest resource inventory of the United States: the Forest Inventory and Analysis (FIA) program of the USDA Forest Service. The FIA program currently limits its inventories to trees in forests meeting specific size and density criteria, but the draft FIA Strategic Plan suggests the addition of an “other treed land inventory” (excluding urban forests). In this study, we use FIA data to estimate the agroforestry and other tree resources of the Midwest and document some obstacles to effective inventories of agroforestry practices. We compare our estimates of forestland area in the Midwest to those derived from MODIS (MODerate Resolution Imaging Spectroradiometer) Vegetative Continuous Fields (VCF). The differences between these two estimates, particularly in sparsely forested states, support the idea that the expansion of the FIA program to an all-tree inventory would fill an important gap. We propose minor modifications to the inventory that would lead to an improved assessment of agroforestry and other tree resources and practices.

Recent observations with the Heliospheric Imagers (HIs) onboard the twin NASA Solar Terrestrial Relations Observatory (STEREO) spacecraft have provided unprecedented observations of a large number of coronal mass ejections (CMEs) in the inner heliosphere. In this article we discuss the generation of the HIGeoCAT CME catalogue and perform a statistical analysis of its events. The catalogue was generated as part of the EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) project ( www.helcats-fp7.eu/ ). It is created by generating time/elongation maps for CMEs using observations from the inner (HI-1) and outer (HI-2) cameras along a position angle close to the CME apex. Next, we apply single-spacecraft geometric-fitting techniques to determine the kinematic properties of these CMEs, including their speeds, propagation directions, and launch times. The catalogue contains a total of 1455 events (801 from STEREO-A and 654 from STEREO-B) from April 2007 to the end of August 2017. We perform a statistical analysis of the properties of CMEs in HIGeoCAT and compare the results with those from the Large Angle Spectrometric Coronagraph (LASCO) CDAW catalogues (Yashiro et al. J. Geophys. Res. Space Phys. 109 , A07105, 2004 ) and the COR-2 catalogue of Vourlidas et al. ( Astrophys. J. 838 , 141, 2004 ) during the same period. We find that the distributions of both speeds and latitudes for the HIGeoCAT CMEs correlate with the sunspot number over the solar cycle. We also find that the HI-derived CME speed distributions are generally consistent with coronagraph catalogues over the solar cycle, albeit with greater absolute speeds due to the differing methods with which each is derived.

We present an analysis of coronal mass ejections (CMEs) observed by the Heliospheric Imagers (HIs) onboard NASA’s Solar Terrestrial Relations Observatory (STEREO) spacecraft. Between August 2008 and April 2014 we identify 273 CMEs that are observed simultaneously, by the HIs on both spacecraft. For each CME, we track the observed leading edge, as a function of time, from both vantage points, and apply the Stereoscopic Self-Similar Expansion (SSSE) technique to infer their propagation throughout the inner heliosphere. The technique is unable to accurately locate CMEs when their observed leading edge passes between the spacecraft; however, we are able to successfully apply the technique to 151, most of which occur once the spacecraft-separation angle exceeds 180 ∘ , during solar maximum. We find that using a small half-width to fit the CME can result in inferred acceleration to unphysically high velocities and that using a larger half-width can fail to accurately locate the CMEs close to the Sun because the method does not account for CME over-expansion in this region. Observed velocities from SSSE are found to agree well with single-spacecraft (SSEF) analysis techniques applied to the same events. CME propagation directions derived from SSSE and SSEF analysis agree poorly because of known limitations present in the latter.

The objective of this experiment was to determine the association of glucocorticoids and markers for immune status in finishing beef steers and heifers with DMI, growth, and efficiency. Steers (n = 127) and heifers (n = 109) were individually fed a finishing ration for 84 d with BW measured every 21 d. Blood samples were collected via jugular venipuncture for metabolite (glucose and lactate) and cortisol analysis and rectal grab samples of feces were collected for corticosterone analysis on d 83 of the experiment. Plasma cortisol was not correlated to DMI (r = -0.08, P > 0.05) or fractional DMI (g DMI/kg BW; r = -0.03; P > 0.05), but was negatively correlated with ADG (r = -0.17, P < 0.01) and G:F (r = -0.20; P < 0.01) and positively correlated to residual feed intake (RFI; r = 0.14, P < 0.05). Fecal corticosterone was positively correlated to fractional DMI (r = 0.15, P < 0.05) and RFI (r = 0.23, P < 0.01) and negatively correlated to G:F (r = -0.18; P < 0.01). Using a mixed model analysis, none of the metabolites or hormones were associated with DMI (P > 0.05), but fecal corticosterone was positively associated with BW-adjusted DMI in heifers only (P = 0.04). Plasma lactate (P < 0.01) was and plasma cortisol (P < 0.10) tended to be negatively associated with ADG. Plasma cortisol (P < 0.05) and fecal corticosterone tended (P < 0.10) to be negatively associated with G:F. Fecal corticosterone was positively associated with RFI in heifers (P < 0.04). In a mixed model analysis, total leukocyte count was positively associated with ADG (P < 0.04) and tended to be positively associated with G:F (P < 0.06). Amongst leukocyte subtypes, neutrophil count was positively associated with ADG in steers (P < 0.02) and monocytes were positively associated with ADG in heifers (P < 0.03). Lymphocyte counts (LY) in steers were negatively associated with DMI (P = 0.03) and fractional DMI (P < 0.03). In heifers, LY tended to be positively associated with DMI (P < 0.09) and BW-adjusted DMI (P < 0.06). Lymphocyte count was also positively associated with ADG (P < 0.01) and G:F (P = 0.05) in heifers. The association of production traits with immune status seems to be different between steers and heifers. There was a stronger relationship of cortisol than fecal corticosterone to feed efficiency measures, suggesting that an cortisol concentrations could be a better marker for feed efficiency traits than fecal corticosterone concentrations.

A universal influenza virus vaccine that does not require frequent updates and/or annual immunizations will offer significant advantages over current seasonal flu vaccines. The highly conserved influenza virus A M2 membrane protein has been previously suggested as a potential antigen target for such a vaccine. Here, we report systematic evaluation of M2 peptide conjugate vaccines (synthetic peptides of M2 extracellular domain conjugated to keyhole limpet hemocyanin (KLH) or Neisseria meningitidis outer membrane protein complex (OMPC)) in mice, ferrets, and rhesus monkeys. The conjugate vaccines were highly immunogenic in all species tested and were able to confer both protection against lethal challenge of either H1N1 or H3N1 virus in mice and reduce viral shedding in the lower respiratory tracts of mice and ferrets. The protection against lethal challenge in mice could also be achieved by passive transfer of monkey sera containing high M2 antibody titers. In addition, we showed that M2 antisera were cross reactive with M2 peptides derived from a wide range of human influenza A strains, but they failed to react with M2 peptides of the pathogenic H5N1 virus (A/Hong Kong/97). The data presented here will permit better understanding of the potential of an M2-based vaccine approach.