Pulse Peak Migration during the Outburst Decay of the Magnetar SGR 1830-0645: Crustal Motion and Magnetospheric Untwisting

Abstract Magnetars, isolated neutron stars with magnetic-field strengths typically ≳1014 G, exhibit distinctive months-long outburst epochs during which strong evolution of soft X-ray pulse profiles, along with nonthermal magnetospheric emission components, is often observed. Using near-daily NICER observations of the magnetar SGR 1830-0645 during the first 37 days of a recent outburst decay, a pulse peak migration in phase is clearly observed, transforming the pulse shape from an initially triple-peaked to a single-peaked profile. Such peak merging has not been seen before for a magnetar. Our high-resolution phase-resolved spectroscopic analysis reveals no significant evolution of temperature despite the complex initial pulse shape, yet the inferred surface hot spots shrink during peak migration and outburst decay. We suggest two possible origins for this evolution. For internal heating of the surface, tectonic motion of the crust may be its underlying cause. The inferred speed of this crustal motion is ≲100 m day−1, constraining the density of the driving region to ρ ∼ 1010 g cm−3, at a depth of ∼200 m. Alternatively, the hot spots could be heated by particle bombardment from a twisted magnetosphere possessing flux tubes or ropes, somewhat resembling solar coronal loops, that untwist and dissipate on the 30–40 day timescale. The peak migration may then be due to a combination of field-line footpoint motion (necessarily driven by crustal motion) and evolving surface radiation beaming. This novel data set paints a vivid picture of the dynamics associated with magnetar outbursts, yet it also highlights the need for a more generic theoretical picture where magnetosphere and crust are considered in tandem.

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Comparison of PV potential models for africa and their potential cost implications.

10.5194/egusphere-egu21-7386 ◽

2021 ◽

Author(s):

Arnold Wasike ◽

Catherina Cader

Keyword(s):

Renewable Energy ◽

Pearson Correlation ◽

Surface Radiation ◽

Geographical Information ◽

Potential Cost ◽

Energy Agency ◽

Data Set ◽

Potential Models ◽

Photo Voltaic ◽

Cost Implications

We currently have more than 7500 planned mini grids, most of them in Africa. These will soon connect more than 27 million people and cost about 12 billion dollars [1]. Africa is in a good position for Photo voltaic (PV) mini grid optimization, receiving more than 1800 KWh/m2 Global Horizontal Irradiation (GHI) every year [2], for most parts of the continent. However, the lack of a coordinated renewable energy monitoring and distribution network works against optimization of PV potential models [3]. This study shows the accuracy of existing photo voltaic potential estimators like renewables ninja [3], the National Renewable Energy Laboratory (NREL), International Renewable Energy Agency (IRENA), and the global solar atlas [2], by comparing the modeled values with long term measurements from ground solar stations. This is done for more than 20 stations distributed over Africa. Our results show best correlations [4] of up to 65.3% from version 2 of the Surface Radiation Data Set from Heliosat (SARAH) derived from the Photovoltaic Geographical Information System (PVGIS). However, we also have correlations as low as 16.2% for models commonly used in off grid simulations. The sensitivities of the modeled cost of a mini grid to the variation in PV potential were tested [5][6] using the statistical range in sourced PV potential from the different estimators, giving us cost variation of more than 2.8% that may arise from the different sources.References1. World Bank, ESMAP - Mini grids for half a billion people2. https://globalsolaratlas.info/map3. doi: 10.1016/j.energy.2016.08.0604. Wikipedia contributors. (2021, January 7). Pearson correlation coefficient. In Wikipedia, The Free Encyclopedia. Retrieved 09:00, January 20, 2021, from https://en.wikipedia.org/w/index.php?title=Pearson_correlation_coefficient&oldid=9989631195. Cader. 20185. Hoffmann. 20197. https://doi.org/10.2136/vzj2018.03.0062

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Flag and boost theories for hot spot forecasting: An application of NIJ’s Real-Time Crime forecasting algorithm using Colorado Springs crime data

International Journal of Police Science & Management ◽

10.1177/1461355719864367 ◽

2019 ◽

Vol 22 (1) ◽

pp. 4-15

Author(s):

YongJei Lee ◽

SooHyun O

Keyword(s):

Hot Spots ◽

High Efficiency ◽

Hot Spot ◽

State Dependence ◽

Population Heterogeneity ◽

Future Research ◽

Theoretical Frameworks ◽

Data Set ◽

Original Algorithm ◽

Colorado Springs

By operationalizing two theoretical frameworks, we forecast crime hot spots in Colorado Springs. First, we use a population heterogeneity (flag) framework to find places where the hot spot forecasting is consistently successful over months. Second, we use a state dependence (boost) framework of the number of crimes in the periods prior to the forecasted month. This algorithm is implemented in Microsoft Excel®, making it simple to apply and completely transparent. Results shows high accuracy and high efficiency in hot spot forecasting, even if the data set and the type of crime we used in this study were different from what the original algorithm was based on. Results imply that the underlying mechanisms of serious and non-serious crime for forecasting are different from each other. We also find that the spatial patterns of forecasted hot spots are different between calls for service and crime event. Future research should consider both flag and boost theories in hot spot forecasting.

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A sea surface radiation data set for climate applications in the tropical western Pacific and South China Sea

Journal of Geophysical Research Atmospheres ◽

10.1029/2000jd900661 ◽

2001 ◽

Vol 106 (D7) ◽

pp. 7219-7228 ◽

Cited By ~ 5

Author(s):

Ming-Dah Chou ◽

Pui-King Chan ◽

Michael M.-H. Yan

Keyword(s):

South China Sea ◽

South China ◽

Western Pacific ◽

Sea Surface ◽

Surface Radiation ◽

Data Set ◽

China Sea ◽

Radiation Data ◽

Tropical Western Pacific

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Large-scale fluctuations of PSBL magnetic flux tubes induced by the field-aligned motion of highly accelerated ions

Annales Geophysicae ◽

10.5194/angeo-28-1273-2010 ◽

2010 ◽

Vol 28 (6) ◽

pp. 1273-1288 ◽

Cited By ~ 15

Author(s):

E. E. Grigorenko ◽

T. M. Burinskaya ◽

M. Shevelev ◽

J.-A. Sauvaud ◽

L. M. Zelenyi

Keyword(s):

Magnetic Field ◽

Magnetic Flux ◽

Plasma Sheet ◽

Large Scale ◽

Low Frequency ◽

Main Magnetic Field ◽

Sudden Increase ◽

Data Set ◽

Flux Tubes ◽

Magnetic Flux Tubes

Abstract. We present a comprehensive analysis of magnetic field and plasma data measured in the course of 170 crossings of the lobeward edge of Plasma Sheet Boundary Layer (PSBL) in the Earth's magnetotail by Cluster spacecraft. We found that large-scale fluctuations of the magnetic flux tubes have been registered during intervals of propagation of high velocity field-aligned ions. The observed kink-like oscillations propagate earthward along the main magnetic field with phase velocities of the order of local Alfvén velocity and have typical wavelengths ~5–20 RE, and frequencies of the order of 0.004–0.02 Hz. The oscillations of PSBL magnetic flux tubes are manifested also in a sudden increase of drift velocity of cold lobe ions streaming tailward. Since in the majority of PSBL crossings in our data set, the densities of currents corresponding to electron-ion relative drift have been low, the investigation of Kelvin-Helmholtz (K-H) instability in a bounded flow sandwiched between the plasma sheet and the lobe has been performed to analyze its relevance to generation of the observed ultra-low frequency oscillations with wavelengths much larger than the flow width. The calculations have shown that, when plasma conditions are favorable for the excitation of K-H instability at least at one of the flow boundaries, kink-like ultra-low frequency waves, resembling the experimentally observed ones, could become unstable and efficiently develop in the system.

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An improved glyoxal retrieval from OMI measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-7-5559-2014 ◽

2014 ◽

Vol 7 (6) ◽

pp. 5559-5599 ◽

Cited By ~ 3

Author(s):

L. M. A. Alvarado ◽

A. Richter ◽

M. Vrekoussis ◽

F. Wittrock ◽

A. Hilboll ◽

...

Keyword(s):

Hot Spots ◽

Anthropogenic Activities ◽

Anthropogenic Emissions ◽

Fire Event ◽

Data Set ◽

Polynomial Degree ◽

Sensitivity Tests ◽

Good Consistency ◽

Radiative Power ◽

Fire Radiative Power

Abstract. Satellite observations from the SCIAMACHY, GOME-2, and OMI spectrometers have been used to retrieve atmospheric columns of glyoxal (CHOCHO) with the DOAS method. High CHOCHO levels are found over regions with large biogenic and pyrogenic emissions, and hot-spots have been identified over areas of anthropogenic activities. This study focuses on the development of an improved retrieval for CHOCHO from measurements by the OMI instrument. From sensitivity tests, an optimal fitting window and polynomial degree are determined. Two different approaches to reduce the interference of liquid water absorption over oceanic regions are evaluated, achieving significant reduction of negative columns over clear water regions. Moreover, a high temperature absorption cross-section of nitrogen dioxide (NO2) is introduced in the DOAS retrieval to account for potential interferences of NO2 over regions with large anthropogenic emissions, leading to improved fit quality over these areas. A comparison with vertical CHOCHO columns retrieved from measurements of the GOME-2 and SCIAMACHY instruments over continental regions is performed, showing overall good consistency. Using the new OMI CHOCHO data set, the link between fires and glyoxal columns is investigated for two selected regions in Africa. In addition, mapped averages are computed for a fire event in the east of Moscow between mid-July and mid-August 2010. In both cases, enhanced CHOCHO levels are found in close spatial and temporal proximity to MODIS fire radiative power, demonstrating that pyrogenic emissions can be clearly identified in the OMI CHOCHO product.

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NYTEFOX – The NY-Ålesund TurbulencE Fiber Optic eXperiment investigating the Arctic boundary layer, Svalbard

10.5194/essd-2021-37 ◽

2021 ◽

Author(s):

Marie-Louise Zeller ◽

Jannis-Michael Huss ◽

Lena Pfister ◽

Karl E. Lapo ◽

Daniela Littmann ◽

...

Keyword(s):

Boundary Layer ◽

Field Experiment ◽

Fiber Optic ◽

Meteorological Data ◽

Surface Radiation ◽

The Arctic ◽

Vertical Profiles ◽

Arctic Boundary Layer ◽

Data Set ◽

Sonic Anemometers

Abstract. The NY-Ålesund TurbulencE Fiber Optic eXperiment, NYTEFOX, was a field experiment at the Arctic site Ny-Ålesund (11.9° E, 78.9° N) and yielded a unique meteorological data set. These data describe the distribution of heat, airflows, and exchange in the Arctic boundary layer for a period of 14 days from 26 February to 10 March 2020. NYTEFOX is the first field experiment to investigate the heterogeneity of airflow and its transport in temperatures, wind, and kinetic energy in the Arctic environment using the Fiber-Optic Distributed Sensing (FODS) technique for horizontal and vertical observations. FODS air temperature and wind speed were observed at a spatial resolution of 0.127 m and 9 s in time along a horizontal array of 700 m at 1 m height above ground level (agl) and along three 7 m vertical profiles. Ancillary data were collected from three sonic anemometers and an acoustic profiler (miniSodar, SOund Detection And Ranging) yielding turbulent flow statistics and vertical profiles in the lowest 300 m agl, respectively. The observations from this field campaign are publicly available on Zenodo (https://doi.org/10.5281/zenodo.4335461) and supplement the data set operationally collected by the Basic Surface Radiation Network (BSRN) meteorological data set at Ny-Ålesund, Svalbard.

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The De-Icing Comparison Experiment (D-ICE): A study of broadband radiometric measurements under icing conditions in the Arctic

10.5194/amt-2020-397 ◽

2020 ◽

Author(s):

Christopher J. Cox ◽

Sara M. Morris ◽

Taneil Uttal ◽

Ross Burgener ◽

Emiel Hall ◽

...

Keyword(s):

Surface Radiation ◽

The Arctic ◽

Data Set ◽

Radiative Fluxes ◽

Cold Environments ◽

Comparison Experiment ◽

North Slope Of Alaska ◽

Operational Systems ◽

Waste Energy ◽

Atmospheric Radiation Measurement

Abstract. Surface-based measurements of broadband shortwave (solar) and longwave (infrared) radiative fluxes using thermopile radiometers are made regularly around the globe for scientific and operational environmental monitoring. The occurrence of ice on sensor windows in cold environments – whether snow, rime, or frost – is a common problem that is difficult to prevent as well as difficult to correct in post-processing. The Baseline Surface Radiation Network (BSRN) community recognizes radiometer icing as a major outstanding measurement uncertainty. Towards constraining this uncertainty, the De-Icing Comparison Experiment (D-ICE) was carried out at the NOAA Atmospheric Baseline Observatory in Utqiaġvik (formerly Barrow), Alaska, from August 2017 to July 2018. The purpose of D-ICE was to evaluate existing ventilation and heating technologies developed to mitigate radiometer icing. D-ICE consisted of 20 pyranometers and 5 pyrgeometers operating in various ventilator housings alongside operational systems that are part of NOAA's Barrow BSRN station and the U.S. Dept. of Energy Atmospheric Radiation Measurement (ARM) Program North Slope of Alaska and Oliktok Point observatories. To detect icing, radiometers were monitored continuously using cameras, with a total of more than 1 million images of radiometer domes archived. Ventilator and ventilator/heater performance overall was skilful with the average of the systems mitigating 77 % of icing and many being 90+ % effective. Ventilators without heating elements were also effective and capable of providing heat through roughly equal contributions of waste energy from the ventilator fan and adiabatic heating downstream of the fan. This provided ~ 0.6 C of warming, enough to subsaturate the air up to a relative humidity (w.r.t. ice) of ~ 105 %. Because the mitigation technologies performed well, a near complete record of verified ice-free radiometric fluxes were assembled for the duration of the campaign. This well-characterized data set is suitable for model evaluation, in particular for the Year of Polar Prediction (YOPP) first Special Observing Period (SOP1). We used the data set to calculate short- and long-term biases in iced sensors, finding that biases can be up to +60 W m−2 (longwave) and −211 to +188 W m−2 (shortwave). However, because of the frequency of icing, mitigation of ice by ventilators, cloud conditions, and the timing of icing relative to available sunlight, the biases in the monthly means were generally less than the aggregate uncertainty attributed to other conventional sources.

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The NY-Ålesund TurbulencE Fiber Optic eXperiment (NYTEFOX): investigating the Arctic boundary layer, Svalbard

Earth System Science Data ◽

10.5194/essd-13-3439-2021 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3439-3452

Author(s):

Marie-Louise Zeller ◽

Jannis-Michael Huss ◽

Lena Pfister ◽

Karl E. Lapo ◽

Daniela Littmann ◽

...

Keyword(s):

Boundary Layer ◽

Field Experiment ◽

Fiber Optic ◽

Meteorological Data ◽

Surface Radiation ◽

The Arctic ◽

Vertical Profiles ◽

Arctic Boundary Layer ◽

Data Set ◽

Sonic Anemometers

Abstract. The NY-Ålesund TurbulencE Fiber Optic eXperiment (NYTEFOX) was a field experiment at the Ny-Ålesund Arctic site (78.9∘ N, 11.9∘ E) and yielded a unique meteorological data set. These data describe the distribution of heat, airflows, and exchange in the Arctic boundary layer for a period of 14 d from 26 February to 10 March 2020. NYTEFOX is the first field experiment to investigate the heterogeneity of airflow and its transport of temperature, wind, and kinetic energy in the Arctic environment using the fiber-optic distributed sensing (FODS) technique for horizontal and vertical observations. FODS air temperature and wind speed were observed at a spatial resolution of 0.127 m and a temporal resolution of 9 s along a 700 m horizontal array at 1 m above ground level (a.g.l.) and along three 7 m vertical profiles. Ancillary data were collected from three sonic anemometers and an acoustic profiler (minisodar; sodar is an acronym for “sound detection and ranging”) yielding turbulent flow statistics and vertical profiles in the lowest 300 m a.g.l., respectively. The observations from this field campaign are publicly available on Zenodo (https://doi.org/10.5281/zenodo.4756836, Huss et al., 2021) and supplement the meteorological data set operationally collected by the Baseline Surface Radiation Network (BSRN) at Ny-Ålesund, Svalbard.

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Athletic Differences in the Characteristics of the Photoplethysmographic Pulse Shape: Effect of Maximal Oxygen Uptake and Maximal Muscular Voluntary Contraction

BioMed Research International ◽

10.1155/2015/752570 ◽

2015 ◽

Vol 2015 ◽

pp. 1-8 ◽

Cited By ~ 5

Author(s):

Anran Wang ◽

Lin Yang ◽

Chengyu Liu ◽

Jingxuan Cui ◽

Yao Li ◽

...

Keyword(s):

Oxygen Uptake ◽

Maximal Oxygen Uptake ◽

Pulse Shape ◽

Voluntary Contraction ◽

Shape Effect ◽

Peak Time ◽

Pulse Area ◽

Reflection Index ◽

Dicrotic Notch ◽

Pulse Peak

This study aimed to investigate the athletic differences in the characteristics of the photoplethysmographic (PPG) pulse shape. 304 athletes were enrolled and divided into three subgroups according to a typical sport classification in terms of the maximal oxygen uptake (MaxO2_low, MaxO2_middle and MaxO2_high groups) or the maximal muscular voluntary contraction (MMVC_low, MMVC_middle, and MMVC_high groups). Finger PPG pulses were digitally recorded and then normalized to derive the pulse area, pulse peak timeTp, dicrotic notch timeTn, and pulse reflection index (RI). The four parameters were finally compared between the three subgroups categorized by MaxO2or by MMVC. In conclusion, it has been demonstrated by quantifying the characteristics of the PPG pulses in different athletes that MaxO2, but not MMVC, had significant effect on the arterial properties.

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