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1. The Growth of Ring Current/SYM‐H Under Northward IMF B _z Conditions Present During the 21–22 January 2005 Geomagnetic Storm

   https://doi.org/10.1029/2023SW003489  

   Rout, Diptiranjan; Patra, S.; Kumar, S.; Chakrabarty, D.; Reeves, G. D.; Stolle, C.; Pandey, K.; Chakraborty, S.; Spencer, E. A. (October 2023, Space Weather)

   Abstract The total energy transfer from the solar wind to the magnetosphere is governed by the reconnection rate at the magnetosphere edges as the Z‐component of interplanetary magnetic field (IMFB_z) turns southward. The geomagnetic storm on 21–22 January 2005 is considered to be anomalous as the SYM‐H index that signifies the strength of ring current, decreases and had a sustained trough value of −101 nT lasting more than 6 hr under northward IMFB_zconditions. In this work, the standard WINDMI model is utilized to estimate the growth and decay of magnetospheric currents by using several solar wind‐magnetosphere coupling functions. However, it is found that the WINDMI model driven by any of these coupling functions is not fully able to explain the decrease of SYM‐H under northward IMFB_z. A dense plasma sheet along with signatures of a highly stretched magnetosphere was observed during this storm. The SYM‐H variations during the entire duration of the storm were only reproduced after modifying the WINDMI model to account for the effects of the dense plasma sheet. The limitations of directly driven models relying purely on the solar wind parameters and not accounting for the state of the magnetosphere are highlighted by this work. 

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2. Optimistic Gittins Indices

   https://doi.org/10.1287/opre.2021.2207  

   Farias, Vivek F; Gutin, Eli (November 2022, Operations Research)

   We propose a tightening sequence of optimistic approximations to the Gittins index in “Optimistic Gittins Indices.” We show that the use of these approximations in concert with the use of an increasing discount factor appears to offer a compelling alternative to state-of-the-art index schemes proposed for the Bayesian multiarmed bandit problem. We prove that the use of these optimistic indices constitutes a regret optimal algorithm. Perhaps more interestingly, the use of even the loosest of these approximations appears to offer substantial performance improvements over state-of-the-art alternatives while incurring little to no additional computational overhead relative to the simplest of these alternatives. 

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3. Superbridge and bridge indices for knots

   https://doi.org/10.1142/S0218216521500097  

   Adams, Colin; Agarwal, Nikhil; Allen, Rachel; Khandhawit, Tirasan; Simons, Alex; Winarski, Rebecca; Wootters, Mary (February 2021, Journal of Knot Theory and Its Ramifications)

   null (Ed.)

   We improve the upper bound on superbridge index [Formula: see text] in terms of bridge index [Formula: see text] from [Formula: see text] to [Formula: see text]. 

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4. Synthesis and novel properties of Q-silicon (January 2023)

   https://doi.org/10.1080/21663831.2023.2224396  

   Narayan, Jagdish; Sundar Sahoo, Siba; Joshi, Naveen; Narayan, Roger (August 2023, Materials Research Letters)
5. Seaglider observations in Davis Strait; 2005-2014

   https://doi.org/10.18739/A2PC2TB3S  

   Lee, Craig (January 2024, NSF Arctic Data Center)

   The Davis Strait observing system was established in 2004 to advance understanding of the role of Arctic – sub-Arctic interactions in the climate system by collecting sustained measurements of physical, chemical and biological variability at one of the primary gateways that connect the Arctic and subpolar oceans. Efforts began as a collaboration between researchers at the University of Washington’s Applied Physics Laboratory and the Canadian Department of Fisheries and Ocean’s Bedford Institute of Oceanography, but has grown to include researchers from the Greenland Institute of Natural Resources, Greenland Climate Institute, Danish Technological University, University of Alberta and University of Colorado, Boulder. The project is a component of the NSF Arctic Observing and Atlantic Meridional Overturning Networks, and the international Arctic-Subarctic Ocean Flux (ASOF) program, Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP), Global Ocean Acidification Observing Network (GOA-ON), Arctic Monitoring Assessment Programme (AMAP) and OceanSITES system. Seaglider observations of temperature and salinity extending from the surface to a maximum of 1000 meter (m) depth were collected in Davis Strait from 2005-2014. Seagliders made repeat transects across Davis Strait between waypoints near 66°45' North (N), 60°30' West (W) and 67°N, 56°30' W (though these waypoints and the pathway of the gliders between the waypoints varied). Acoustic navigation enabled year-round data collection. This dataset contains 15 files, each of which contains Level 3 data from one Seaglider deployment in Davis Strait. Deployments lasted from 11 to 174 days and had a median duration of 83 days. Files contain several temperature and salinity products: data not interpolated or despiked; data despiked and interpolated to a common depth/time grid; and low-pass filtered data. Files also include quality control (QC) flags. Each file also contains depth-averaged current vectors from the Seaglider flight model and surface current vectors estimated from the Seaglider's drift track. Data files are named as follows: sg<seaglider number>_DavisStrait_<deployment data in MmmYY format>_level3.nc Level 2 files containing individual dive data are available by contacting the dataset creator. More details about the project can be found at https://iop.apl.washington.edu/project.php?id=davis. 

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