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Abstract Full-disk measurements of the solar magnetic field by the Helioseismic and Magnetic Imager (HMI) are often used for magnetic field extrapolations, but its limited spatial and spectral resolution can lead to significant errors. We compare HMI data with observations of NOAA 12104 by the Hinode Spectropolarimeter (SP) to derive a scaling curve for the magnetic field strength,B. The SP data in the Feilines at 630 nm were inverted with the SIR code. We find that the Milne–Eddington inversion of HMI underestimatesBand the line-of-sight flux, Φ, in all granulation surroundings by an average factor of 4.5 in plage and 9.2 in the quiet Sun in comparison to the SP. The deviation is inversely proportional to the magnetic fill factor,f, in the SP results. We derived a correction curve to match the HMIBwith the effective fluxBfin the SP data that scaled HMIBup by 1.3 on average. A comparison of non-force-free field extrapolations over a larger field of view without and with the correction revealed minor changes in connectivity and a proportional scaling of electric currents and Lorentz force (∝B∼ 1.3) and free energy (∝B² ∼ 2). Magnetic field extrapolations of HMI vector data with large areas of plage and quiet Sun will underestimate the photospheric magnetic field strength by a factor of 5–10 and the coronal magnetic flux by at least a factor of 2. An HMI inversion including a fill factor would mitigate the problem. 

Lithologic correlation of the Middle Devonian Traverse Group in the Michigan Basin is challenging due to a paucity of outcrops and the difficulty in correlating shallow water marine facies across the basin.This study correlates strata in the State Chester Welch #18 core (SCW-18) to outcrop exposures at the type sections of the Thunder Bay Formation and neighboring units using litho- and chemostratigraphy. Lithologically, the texture, grain sizes, and fossil assemblages found in the SCW-18 core match the outcrop samples and type section description of the Thunder Bay Formation. Both successions are gray calcareous shale and limestone with abundant fossils and stylolites. δ13C isotopes reveal a shift to more negative isotopic values through time for both bulk-rock and drilled micrite powders from the SCW-18 core, but a trend toward more positive values with relative stratigraphic position for the outcrop sample. This suggests that Thunder Bay strata in the core and outcrop are not chronostratigraphically equivalent even though they appear similar lithologically. The core data also revealed two groupings based on relationships between δ18O vs δ13C values that correspond to differences in lithology. The lower samples in the core that are situated in shaley limestone illustrate a linear trend than the upper portion which was more crystalline and isotopic values noisier. This variation might suggest differences in diagenetic processes affecting the subsurface Thunder Bay Formation as δ18O values in carbonates are often altered to some extent. This study improves our lithologic and isotope geochemistry understanding of the Thunder Bay Formation in the subsurface. Future work will incorporate elemental data from the core and outcrop to better understand diagenetic processes. 

Abstract Understanding the mechanisms underlying the heating of the solar atmosphere is a fundamental problem in solar physics. The lower atmosphere of the Sun (i.e., photosphere and chromosphere) is composed of weakly ionized plasma. This results in anisotropic dissipation of electric currents by Coulomb and Cowling resistivities. Joule heating due to dissipation of currents perpendicular to the magnetic field by Cowling resistivity has been demonstrated to be the main mechanism for the heating of a sunspot umbral light bridge located in NOAA AR 12002 on 2014 March 13. Here, we focus on the same target region and demonstrate the importance of further constraining our Joule heating model using observational data in addition to magnetic field, namely plasma temperature calculated from the inversion of spectroscopic data obtained from the Interferometric BI-dimensional Spectrometer instrument of the ground-based Dunn Solar Telescope. As a parameter in our analysis, temperature is demonstrated to have the highest sensitivity after magnetic field. We show that the heating of the light bridge is a highly dynamic event that necessitates utilization of 3D spatially resolved observational data for temperature rather than a 1D temperature stratification based on theoretical/semiempirical solar atmosphere models. Our improved data-constrained analysis using spatially resolved temperatures shows that the entire light bridge is heated by the proposed mechanism, and yields heating rate values that are consistent with our previous study. 

Recent calls for increased inclusion in & access to authentic course-based research have been building on the momentum of support for Course-Based Undergraduate Research Experiences (CUREs). However, these courses can be very challenging to implement at scale or with low resources. To equitably provide these critical science process skills to the largest possible cohort of students, we have developed a new student research project within our first-year biology lab. Our student team research project is integrated throughout the semester, building authentic science process skills from start to finish. Students start from a research idea, develop a multi-site experimental design, do hands-on data collection at home, analyze quantitative data, and present their findings in a conference-style format. We have also embedded structured time for building collaborative skills. This novel change to our lab curriculum runs online, hybrid or face-to-face; it has no lab budget costs; and it has been well-received in multiple offerings of our course of ~200-600 students. It also has allowed us to improve our assessments: we evaluate writing (graphical abstracts) and/or oral presentation skills. Further, our lab exam can now be more cognitively challenging because our new curriculum better prepares students to analyze, evaluate, and synthesize. This article demonstrates that we can reduce barriers to doing authentic research, at scale in introductory courses; and we include here all materials needed to adapt this project to your own context. 

Context. The inverse Evershed flow (IEF) is a mass motion towards sunspots at chromospheric heights. Aims. We combined high-resolution observations of NOAA 12418 from the Dunn Solar Telescope and vector magnetic field measurements from the Helioseismic and Magnetic Imager (HMI) to determine the driver of the IEF. Methods. We derived chromospheric line-of-sight (LOS) velocities from spectra of H α and Ca  II IR. The HMI data were used in a non-force-free magnetic field extrapolation to track closed field lines near the sunspot in the active region. We determined their length and height, located their inner and outer foot points, and derived flow velocities along them. Results. The magnetic field lines related to the IEF reach on average a height of 3 megameter (Mm) over a length of 13 Mm. The inner (outer) foot points are located at 1.2 (1.9) sunspot radii. The average field strength difference Δ B between inner and outer foot points is +400 G. The temperature difference Δ T is anti-correlated with Δ B with an average value of −100 K. The pressure difference Δ p is dominated by Δ B and is primarily positive with a driving force towards the inner foot points of 1.7 kPa on average. The velocities predicted from Δ p reproduce the LOS velocities of 2–10 km s −1 with a square-root dependence. Conclusions. We find that the IEF is driven along magnetic field lines connecting network elements with the outer penumbra by a gas pressure difference that results from a difference in field strength as predicted by the classical siphon flow scenario.