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- Creator:
- Brenner, Austin, M
- Description:
- Coupling between the solar wind and magnetosphere can be expressed in terms of energy transfer through the separating boundary known as the magnetopause. Geospace simulation is performed using the Space Weather Modeling Framework (SWMF) of a multi-ICME impact event on February 18-20, 2014 in order to study the energy transfer through the magnetopause during storm conditions. The magnetopause boundary is identified using a modified plasma $\beta$ and fully closed field line criteria to a downstream distance of $-20R_{e}$. Observations from Geotail, Themis, and Cluster are used as well as the Shue 1998 model to verify the simulation field data results and magnetopause boundary location. Once the boundary is identified, energy transfer is calculated in terms of total energy flux \textbf{K}, Poynting flux \textbf{S}, and hydrodynamic flux \textbf{H}. Surface motion effects are considered and the regional distribution of energy transfer on the magnetopause surface is explored in terms of dayside $\left(X>0\right)$, flank $\left(X<0\right)$, and tail cross section $\left(X=X_{min}\right)$ regions. It is found that total integrated energy flux over the boundary is nearly balanced between injection and escape, and flank contributions dominate the Poynting flux injection. Poynting flux dominates net energy input, while hydrodynamic flux dominates energy output. Surface fluctuations contribute significantly to net energy transfer and comparison with the Shue model reveals varying levels of cylindrical asymmetry in the magnetopause flank throughout the event. Finally existing energy coupling proxies such as the Akasofu $\epsilon$ parameter and Newell coupling function are compared with the energy transfer results.
- Keyword:
- Space plasma, Magnetosphere, MHD simulations, Magnetopause, Substorm, Energy transfer, and Poynting flux
- Citation to related publication:
- Brenner A, Pulkkinen TI, Al Shidi Q and Toth G (2021) Stormtime Energetics: Energy Transport Across the Magnetopause in a Global MHD Simulation. Front. Astron. Space Sci. 8:756732. doi: 10.3389/fspas.2021.756732
- Discipline:
- Science
-
- Creator:
- Brandt, Daniel, A. and Ridley, Aaron, J.
- Description:
- The research that produced this data focused on conducting a statistical comparison between horizontal winds modeled with GITM and those derived from the accelerometer aboard the GOCE satellite. The winds from GITM and GOCE were compared by constructing their respective probability densities under different levels of geomagnetic activity, and by distributing them as a function of geomagnetic activity, magnetic latitude, magnetic local time, day-of-the-year, and solar radio flux.
- Keyword:
- Thermosphere, GITM, GOCE, Neutral winds, and Thermospheric modeling
- Discipline:
- Science and Engineering
-
- Creator:
- Lehman, John T
- Description:
- The research was directed at the trophic dynamics, food web structure, and secondary production of lower food web members of the Great Lakes ecosystem. It documented species invasion of the upper Great Lakes by the Eurasian invertebrate predator Bythotrephes, commonly called the spiny water flea.
- Keyword:
- Invasive Species, Limnology, Trophic Dynamics, Zooplankton, Water Chemistry, Secondary Production, Lake Erie, Lake Huron, Lake Michigan, and Lake Superior
- Citation to related publication:
- Burgess, S., E.W. Jackson, L. Schwarzman, N. Gezon, and J.T. Lehman. 2015. Improved estimates of calanoid copepod biomass in the St. Lawrence Great Lakes. Journal of Great Lakes Research 41: 484-491., Doubek, J.P. and J.T. Lehman. 2014. Historical trophic position of Limnocalanus macrurus in Lake Michigan. Journal of Great Lakes Research 40: 1027-1032., Jackson, E.W., J.P. Doubek, J.S. Schaeffer, and J.T. Lehman. 2013. Historical and Recent Biomass and Food Web Relations of Limnocalanus in Lake Huron. Journal of Great Lakes Research 39: 404-408., Doubek, J. P. and J.T. Lehman. 2011. Historical biomass of Limnocalanus in Lake Michigan. Journal of Great Lakes Research 37: 159-164., Sullivan, C. and J.T. Lehman. 1998. Character variation and evidence for spine length selection in the invertebrate predator Bythotrephes (Crustacea: Cladocera) from Lakes Michigan, Huron, and Erie. Arch. Hydrobiol. 142: 35-52., Bilkovic, D.M. and J.T. Lehman. 1997. Lipid content and size variation of Bythotrephes (Cladocera: Cercopagidae) from Lakes Erie, Huron and Michigan. J. Great Lakes Research 23: 149-159., Lehman, J.T., D.M. Bilkovic, and C. Sullivan. 1997. Predicting development, metabolism, and secondary production for the invertebrate predator Bythotrephes. Freshwater Biology 38:343-352., Lehman, J.T. and D.A. Lehman. 1996. Status of the non-indigenous invertebrate predator Bythotrephes cederstroemi (Crustacea: Cladocera) in Lakes Erie, Huron, and Michigan. Proc. Symp. on non-indigenous species in Western Aquatic Ecosystems. Portland State Univ. Lakes and Reservoirs Program Publication No. 96-8: 7-14. , Branstrator, D.K. and J.T. Lehman. 1996. Evidence for juvenile fish predation on Bythotrephes cederstroemi in Lake Michigan. J. Great Lakes Research 22: 917-924., Lehman, J.T. and D.K. Branstrator 1996. Predicting assimilation and development rates of invertebrate predators. J. Great Lakes Research 22: 930-934., Lehman, J.T. and D.K. Branstrator. 1995. A model for growth, development, bioenergetics and diet selection by the invertebrate predator Bythotrephes cederstroemi. J. Great Lakes Research 21: 610-619., Burkhardt, S. and J.T. Lehman. 1994. Prey consumption and predatory effects of an invertebrate predator (Bythotrephes: Cladocera, Cercopagidae) based on phosphorus budgets. Limnol. Oceanogr. 39: 1007-1019., Lehman, J.T. and C. Caceres. 1993. Food web responses to species invasion by a predatory invertebrate: Bythotrephes in Lake Michigan. Limnology and Oceanography 37: 879-891., Branstrator, D.K. and J.T. Lehman. 1991. Invertebrate predation in Lake Michigan: Regulation of Bosmina longirostris by Leptodora kindti. Limnology and Oceanography 36: 483-495., Lehman, J.T. 1991. Causes and consequences of cladoceran dynamics in Lake Michigan: Implications of species invasion by Bythotrephes. Journal of Great Lakes Research 17: 437-445., Lehman, J.T., J.A. Bowers, R.W. Gensemer, G.J. Warren, and D.K. Branstrator. 1990. Mysis relicta in Lake Michigan: Abundances and relationships with their potential prey, Daphnia. Canadian J. Fisheries and Aquatic Sciences 47: 977-983., Lehman, J.T. and C.D. Sandgren. 1990. Trophic dynamics of Lake Michigan: Response of algal production to changes in the zooplankton community. Verh. Internat. Verein. Limnol. 24: 397-400., Sandgren, C.D. and J.T. Lehman. 1990. Response of chlorophyll a, phytoplankton, and microzooplankton to the invasion of Lake Michigan by Bythotrephes. Verh. Internat. Verein. Limnol. 24: 386-392., Lehman, J.T. 1988. Algal biomass unaltered by food web changes in Lake Michigan. Nature 332: 537-538., Warren, G.J. and J.T. Lehman. 1988. Young-of-the-year Coregonus hoyi in Lake Michigan: Prey selection and influence on the zooplankton community. Journal of Great Lakes Research 14: 420-426., Dorazio, R.M., J.A. Bowers, and J.T. Lehman. 1987. Food-web manipulations influence grazer control of phytoplankton growth rates in Lake Michigan. Journal of Plankton Research 9: 891-899., and Lehman, J.T. 1987. Palearctic predator invades North American Great Lakes. Oecologia 74: 478-480.
- Discipline:
- Science
-
- Creator:
- Alsip, Peter
- Description:
- Percent Weight Change Data: The model was run continuously on a daily time step for seasonal intervals (Spring: March thru May; Summer: June thru August; Fall: September thru November) as well as contiguously from Spring to Fall to assess total growth over the likely growing season (March thru November). CSV files represent the simulated weight change (%) of Bighead and Silver Carp for the respective time periods associated with the file name. Initial fish mass for each seasonal interval and growing season was 4350 g for Silver Carp and 5480 g for Bighead Carp. Maximum and mean total weight change (%) was determined for three depth ranges (near surface depths [NS]: 0 – 10 m; deep chlorophyll layer depths [DCL]: 10 - 50 m; and whole water column [WC]). Coordinates are in decimal degrees. File naming convention: speciesSeasonWtChange (e.g. bigheadFallWtChange = % weight change of Bighead Carp from September through November) , Monthly Habitat Quality Data: Rdata files contain matrices of Bighead or Silver carp growth rate potential as represented as a mass-proportional growth rate (gram of carp/gram of carp/day [g/g/d]) for the 15th day of each month. Habitats with growth rate potential >= 0 g/g/d were deemed suitable. Matrix attributes: Rows: Row numbers refer to the spatial node with 20 equally-spaced vertical layers. Columns: Columns 1-20 refer to the growth rate potential value for each vertical layer of each node. Vertical layers are evenly spaced based on the total depth of the water column for each node. Depth for each node can be found in the grid attributes data file. Columns 21 ("meanG") and 22 ("Gmax") represent the average and maximum growth rate potential, respectively, of the fish across the whole water column for the corresponding node. File naming convention: species_MonthNumber (e.g. silver_06 = Silver carp growth rate potential in June) Spatial coordinates for each node can be found in the grid attributes data files., Grid attributes data: This Rdata file provides the spatial reference data and other grid attributes. Coordinates are provided in UTM (x & y) and latitude and longitude (decimal degrees). Depth (meters) for each node is listed in this file. , GRP Model code: Details bioenergetics equations, foraging equation, functions for running the model on a monthly time-step and daily time step, and functions for basic analyses. Model is coded in R., and The simulated input data (prey and temperature) used to run our model is not included in this data set. Instead we provide the model code, grid attributes, and outputs of the model. The readRDS() function (R Base Package v.3.5.1) is required to read in .Rdata files in R.
- Keyword:
- Asian Carp, Laurentian Great Lakes, Habitat Suitability, Invasive Species, Lake Michigan, and Ecological Modeling
- Discipline:
- Science
-
- Creator:
- Al Shidi, Q. and Pulkkinen, T.
- Description:
- Provided are the resultant and processed data.
- Keyword:
- space physics, ground magnetometers, magnetosphere, numerical space physics, solar wind, numerical space physics, and ionosphere
- Discipline:
- Science
-
- Creator:
- Zhou, Peng and Mi, Zetian
- Description:
- Production of hydrogen fuel from sunlight and water offers one of the most promising pathways for carbon neutrality. Some solar hydrogen production approaches, e.g., photoelectrochemical water splitting, often requires corrosive electrolyte, limiting their performance stability and environmental sustainability. Alternatively, clean hydrogen can be produced directly from tap water, or seawater by wireless photocatalytic water splitting. The solar-to-hydrogen (STH) efficiency, however, is still lower than 3%. Herein, we have developed a unique strategy to overcome the efficiency bottleneck. A high STH efficiency of 9.2% was achieved by utilizing pure water, concentrated solar light, and visible-light-responsive InGaN photocatalyst. The success of this strategy was explained by the synergistic effects of promoting forward hydrogen-oxygen evolution and inhibiting the reverse hydrogen-oxygen recombination by operating at an optimal reaction temperature (~70 °C). Such an optimal temperature can be readily achieved by harvesting the previously wasted infrared light of the solar spectrum without other energy consumption. This temperature-dependent strategy also leads to the STH efficiencies of ~7% from the widely available tap water and seawater. A large-scale photocatalytic water splitting system with a natural solar light capacity of 257 W on a 4 cm × 4 cm photocatalyst wafer achieves a STH of 6.2% at ~70 oC. Our study offers a practical approach to produce hydrogen fuel efficiently from natural solar and water, overcoming some of the major barriers for green hydrogen economy.
- Keyword:
- photocatalysis, water splitting, and solar hydrogen
- Discipline:
- Science
-
- Creator:
- Engebretson, Mark J.
- Description:
- Large geomagnetic disturbances (GMDs, also denoted as MPEs - magnetic perturbation events) have sufficient amplitude to cause geomagnetically induced currents (GICs) that can damage technical infrastructure. In this study we present occurrence statistics for GMD / MPE events with derivatives ≥ 6 nT/s and ≥ 20 nT/s from five stations in the MACCS and AUTUMNX magnetometer arrays in Arctic Canada at magnetic latitudes ranging from 65° to 75°. Earlier studies using data from these arrays (Engebretson et al., 2019a,b, 2021a,b) covered only two years (2015 and 2017) and focused on latitude- and local time-dependent occurrence patterns and short-term dependencies on solar wind/IMF parameters and magnetospheric activity indices. This study presents all available data from these stations from 2011 through 2022 to analyze variations of GMD activity over a full solar cycle. Intense GMD activity did not closely follow the sunspot cycle, but instead was lowest during its rising phase and maximum (2011-2014), was highest during the early declining phase (2015-2017), and reached a subsequent minimum early in the following sunspot cycle (2020). GMDs with amplitude >20 nT/s followed the same yearly pattern but peaked even more strongly during 2015-2017. Most of these GMDs were associated with high-speed solar wind streams (Vsw > 600 km/s), but not with strongly negative values of the SYM/H index. The majority of these GMDs, irrespective of the Vsw value, were accompanied within 10 min (and most often less) by other events with amplitude ≥ 6 nT/s and showed a mostly poleward progression. These results show that large amplitude but spatially localized nighttime GMDs are primarily associated with high-speed stream geomagnetic drivers during the declining phase of the solar cycle. This indicates that large GIC hazard conditions can occur for a variety of solar wind drivers and geomagnetic conditions and not only for fast-coronal mass ejection driven storms.
- Keyword:
- geomagnetic disturbance events, geomagnetically induced currents
- Citation to related publication:
- Engebretson, M. J., Steinmetz, Yang, L., Pilipenko, V. A., Moldwin, M. B., McCuen, B. A., Connors, M. G., Weygand, J. M., Waters, C. L., Lyons, L. R., Nishimura, Y., Russell, C. T. (2023) Solar Cycle Dependence of Very Large Nighttime Geomagnetic Disturbances (GMDs) Observed in Eastern Arctic Canada. Journal of Geophysical Research – Space Physics
- Discipline:
- Science
-
- Creator:
- Brian C. Weeks
- Description:
- Description: Each folder contains all of the data for a specific specimen; the folder names correspond to the University of Michigan Museum of Zoology catalog number for the specimen. Folders with a “-“ in the name are individual specimens that were photographed multiple independent times; the number following the “-“ indicates the repetition number (i.e. the folder named “UMMZ_242382-10” contains the tenth set of photographs for specimen UMMZ 242382). The photographs are necessary to train and test the Skelevision model, which is a computer vision approach to identifying and measuring elements of the skeleton (length of the tibiotarsus, tarsometatarsus, femur, humerus, ulna, radius, carpometacarpus, 2nd digit 1st phalanx, skull, and keel; the outer diameter of the sclerotic ring at its widest point; and the distance from the back of the skull to the tip of the bill). The data span 115 species of passerines across 79 genera from 59 families.
- Keyword:
- Bird skeleton, neural network, and functional traits
- Citation to related publication:
- Weeks, B.C., Zhou, Z., O’Brien, B., Darling, R., Dean, M., Dias, T., Hassena, G., Zhang, M., and Fouhey, D.F. 2022. A deep neural network for high throughput measurement of functional traits on museum skeletal specimens. Methods in Ecology and Evolution. https://doi.org/10.1111/2041-210X.13864
- Discipline:
- Science
-
- Creator:
- Hayward, Stephen L. , Lund, Paul E., Kang, Qing, Johnson-Buck, Alexander , Tewari, Muneesh, and Walter, Nils G.
- Description:
- This work contains the experimental data and associated analysis that are described in the research publication entitled "Ultra-specific and Amplification-free Quantification of Mutant DNA by Single-molecule Kinetic Fingerprinting". This work contains multiple zip files, each of which represents one of the principal experiment groups presented in the publication. Each experiment group contains movie and analysis files corresponding to various experimental conditions related to that experiment group.
- Keyword:
- Single Molecule Fluorescence, Super-Resolution Microscopy, Nucleic Acid Hybridization, T790M Mutation, Cytosine Deamination, SiMREPS, and single molecule kinetic fingerprinting
- Citation to related publication:
- https://pubs.acs.org/doi/10.1021/jacs.8b06685
- Discipline:
- Science
-
- Creator:
- Hou, Qian, Chatterjee, Surajit, Lund, Paul E., Suddala, Krishna C., and Walter, Nils G.
- Description:
- Bacteria live in a broad range of environmental temperatures that require adaptations of their RNA sequences to maintain function. Riboswitches are regulatory RNAs that change conformation upon binding of typical metabolite ligands to control bacterial gene expression. The paradigmatic small class-I preQ1 riboswitches from the mesophile Bacillus subtilis (Bsu) and the thermophile Thermoanaerobacter tengcongensis (Tte) adopt similar pseudoknot structures when bound to preQ1. Here, we use single-molecule detected chemical denaturation by urea to compare the thermodynamic and kinetic folding properties of the two riboswitches, and the urea-countering effects of trimethylamine N-oxide (TMAO). This data includes the experimental findings and associated analyses detailed in the research article titled "Single-molecule FRET observes opposing effects of urea and TMAO on structurally similar meso- and thermophilic riboswitch RNAs". The data consists of multiple zip files, each representing an experiment that corresponds to the key results in the publication. Each experiment includes movies, qualifying smFRET trajectories, and analysis files related to various conditions within that experimental group.
- Keyword:
- Riboswitch, Single molecule FRET, RNA folding, UV-melting, Osmolyte, Urea, and Trimethylamine N-oxide
- Citation to related publication:
- https://doi.org/10.1093/nar/gkad866
- Discipline:
- Science