Conjugate pulsating aurora and chorus waves: case study at high temporal resolution

Studies have shown a broad correlation between pulsating aurora, chorus waves, and electron scattering, but most studies have used either low time resolution waveform data, high time resolution waveform data over short periods of time, or waveform data without direct crossover of an all sky camera field of view. For the present study, we analyze three nights in Oct 2016 with conjugate Van Allen Probe (VAP) chorus wave observations and HAARP all sky camera (ASC) pulsating aurora observations. We use VAP burst mode waveform data collected for about an hour at 16,000 samples/s during direct VAP crossover of the HAARP ASC FOV in Gakona, AK. Our high-resolution analysis indicates a more complicated relationship between individual aurora pulsations and chorus wave elements.We show in previous study that for each VAP ASC crossover event on October 16 2016, the chorus wave elements observed by VAP do not correspond well to the detailed dynamics of the pulsating aurora. We compare the individual chorus wave elements to the extracted all sky camera optical intensity fluctuations along the mapped magnetic footpoint determined by four separate field line models. Our Poynting flux analysis shows chorus wave propagation towards the northern hemisphere. Based on previous results using THEMIS data, we would expect to see good correlation between the observed chorus waves above the magnetic equator and the pulsating aurora dynamics in the northern hemisphere. However, observed chorus waves may be distorted during propagation away from the generation region or non-linear wave effects may play a role.In this study we extend our analysis to the VAP ASC crossover events on October 13 and 19 2016. We expand our methodologies for optical intensity extraction of ASC images. We seek to draw connections between the characteristics of the individual chorus wave elements and the correlation to pulsating aurora dynamics to better identify particular chorus wave electron resonance conditions.

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Elemental composition of ambient aerosols measured with high temporal resolution using an online XRF spectrometer

10.5194/amt-2016-383 ◽

2017 ◽

Author(s):

Markus Furger ◽

María Cruz Minguillón ◽

Varun Yadav ◽

Jay G. Slowik ◽

Christoph Hüglin ◽

...

Keyword(s):

Trace Elements ◽

Data Quality ◽

Time Resolution ◽

Geographic Distance ◽

Major Elements ◽

High Temporal Resolution ◽

High Time Resolution ◽

Field Campaign ◽

Analysis Methods ◽

Pm10 Mass

Abstract. An Xact 625 ambient metals monitor was tested during a three-week field campaign at the rural, traffic-influenced site Härkingen in Switzerland during summer of 2015. The objective was to characterize the handling and operation of the instrument, evaluate the data quality by intercomparison with other independent measurements, and test its applicability for aerosol source quantification. The Xact was configured to measure 24 elements in PM10 with 1-h time resolution. Hourly element concentrations ranged from a few ng m−3 for trace elements in background conditions to tens of µg m−3 for major elements during a high-emission event (fireworks). The total Xact element mass comprised approximately 20 % of the total PM10 mass. The six major elements Si, S, Cl, K, Ca, and Fe contributed 95 % to the Xact PM10 mass, the remaining 5 % were attributed to the trace elements. Data quality was evaluated by intercomparison with 24-h PM10 filter data analysed with ICP-OES for major elements, ICP-MS for trace elements, and gold amalgamation atomic absorption spectrometry for Hg. 10 elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, Ba, Pb) showed an excellent correlation between the compared methods, with r2 values ≥ 0.95, even though the Xact 625 yielded approximately 28 % higher elemental concentrations than ICP for these elements. These elements demonstrate the high precision of the Xact instrument. An average 28 percent difference to ICP analyses might in part be attributed to the differences in the sampling systems (inlets), the geographic distance between the inlets and between the inlets and the freeway, and to uncertainties in the different analysis methods. 10 additional elements (Cr, V, Co, Ni, As, Se, Cd, Sn, Hg, Bi) could not be compared to a reference, because their concentrations were close to or below the minimum detection limits of at least one of the analysis methods. Sb revealed a calibration issue with the Xact, which requires correction. Si, Cl and Pt were not analysed with ICP, and thus could not be evaluated. The well-quantified elements were further used for a simple investigation of sources. The field campaign encompassed the Swiss National Day fireworks event, providing increased concentrations and unique chemical signatures compared to non-fireworks (or background) periods. Fireworks and traffic or rural background emissions could clearly be identified with their element mixture. The results demonstrate that multi-metal characterization at high-time resolution capability of Xact is a valuable and practical tool for ambient monitoring, exhibiting significant advantages compared to traditional elemental analysis methods.

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Elemental composition of ambient aerosols measured with high temporal resolution using an online XRF spectrometer

Atmospheric Measurement Techniques ◽

10.5194/amt-10-2061-2017 ◽

2017 ◽

Vol 10 (6) ◽

pp. 2061-2076 ◽

Cited By ~ 27

Author(s):

Markus Furger ◽

María Cruz Minguillón ◽

Varun Yadav ◽

Jay G. Slowik ◽

Christoph Hüglin ◽

...

Keyword(s):

Data Quality ◽

Time Resolution ◽

Absorption Spectrometry ◽

Major Elements ◽

High Temporal Resolution ◽

High Time Resolution ◽

Ambient Aerosols ◽

Field Campaign ◽

Chemical Signatures ◽

Icp Ms

Abstract. The Xact 625 Ambient Metals Monitor was tested during a 3-week field campaign at the rural, traffic-influenced site Härkingen in Switzerland during the summer of 2015. The field campaign encompassed the Swiss National Day fireworks event, providing increased concentrations and unique chemical signatures compared to non-fireworks (or background) periods. The objective was to evaluate the data quality by intercomparison with other independent measurements and test its applicability for aerosol source quantification. The Xact was configured to measure 24 elements in PM10 with 1 h time resolution. Data quality was evaluated for 10 24 h averages of Xact data by intercomparison with 24 h PM10 filter data analysed with ICP-OES for major elements, ICP-MS for trace elements, and gold amalgamation atomic absorption spectrometry for Hg. Ten elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, Ba, Pb) showed excellent correlation between the compared methods, with r2 values ≥  0.95. However, the slopes of the regressions between Xact 625 and ICP data varied from 0.97 to 1.8 (average 1.28) and thus indicated generally higher Xact elemental concentrations than ICP for these elements. Possible reasons for these differences are discussed, but further investigations are needed. For the remaining elements no conclusions could be drawn about their quantification for various reasons, mainly detection limit issues. An indirect intercomparison of hourly values was performed for the fireworks peak, which brought good agreement of total masses when the Xact data were corrected with the regressions from the 24 h value intercomparison. The results demonstrate that multi-metal characterization at high-time-resolution capability of Xact is a valuable and practical tool for ambient monitoring.

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Pushing the temporal resolution in absorption and Zernike phase contrast nanotomography: enabling fast in situ experiments

Journal of Synchrotron Radiation ◽

10.1107/s1600577520007407 ◽

2020 ◽

Vol 27 (5) ◽

pp. 1339-1346 ◽

Cited By ~ 3

Author(s):

Silja Flenner ◽

Malte Storm ◽

Adam Kubec ◽

Elena Longo ◽

Florian Döring ◽

...

Keyword(s):

Image Quality ◽

Temporal Resolution ◽

Time Resolution ◽

Phase Contrast ◽

High Temporal Resolution ◽

High Time Resolution ◽

X Ray ◽

Wide Range ◽

In Situ Experiments

Hard X-ray nanotomography enables 3D investigations of a wide range of samples with high resolution (<100 nm) with both synchrotron-based and laboratory-based setups. However, the advantage of synchrotron-based setups is the high flux, enabling time resolution, which cannot be achieved at laboratory sources. Here, the nanotomography setup at the imaging beamline P05 at PETRA III is presented, which offers high time resolution not only in absorption but for the first time also in Zernike phase contrast. Two test samples are used to evaluate the image quality in both contrast modalities based on the quantitative analysis of contrast-to-noise ratio (CNR) and spatial resolution. High-quality scans can be recorded in 15 min and fast scans down to 3 min are also possible without significant loss of image quality. At scan times well below 3 min, the CNR values decrease significantly and classical image-filtering techniques reach their limitation. A machine-learning approach shows promising results, enabling acquisition of a full tomography in only 6 s. Overall, the transmission X-ray microscopy instrument offers high temporal resolution in absorption and Zernike phase contrast, enabling in situ experiments at the beamline.

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ALBEDO RETRIEVING FROM DSCOVR/EPIC DATA AND PRELIMINARY VALIDATION

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xlii-3-w9-147-2019 ◽

2019 ◽

Vol XLII-3/W9 ◽

pp. 147-152

Author(s):

Q. Y. Tian ◽

Q. Liu ◽

H. W. Zhang ◽

Y. H. Che ◽

Y. N. Wen ◽

...

Keyword(s):

Climate Change ◽

Remote Sensing ◽

Time Resolution ◽

Land Surface ◽

Surface Albedo ◽

High Temporal Resolution ◽

High Time Resolution ◽

Observation Data ◽

Climate Change Research ◽

Wide Range

Abstract. Land surface albedo plays an important role in climate change research. Satellite remote sensing has the characteristic of wide observation range, and it can make repeated observations on the same area. Therefore, using the remote sensing data to retrieve surface albedo becomes a main method to obtain the surface albedo in a wide range or even on a global scale. However, the time resolution of existing albedo products is usually low, which has a great impact on the analysis of rapid changes in surface vegetation and the climate change research. The Deep Space Climate Observatory (DSCOVR) was launched to a sun-earth first Lagrange point (L1) orbit, which is a new and unique vantage point to observe the continuously full, sunlit disk of Earth. DSCOVR can provide observation data with high time resolution, therefore, it is necessary to explore the feasibility of the new sensor DSCOVR/EPIC inversion of the daily albedo product. The relationship between the surface broadband albedo and the surface reflectance was established, and then the surface albedo with high temporal resolution was calculated using the DSCOVR/EPIC data. The Inner Mongolia Autonomous Region and parts of the Sahara Desert were selected to verify the accuracy of DSCOVR albedo compared with MODIS albedo. The results show that the correlation coefficients between DSCOVR albedo and MODIS albedo are greater than 0.7 and RMSE are less than 0.05 both in visible band and shortwave band. It can be seen that this method can be used for the albedo retrieval using DSCOVR/EPIC data.

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Ducted propagation of chorus waves: Cluster observations

Annales Geophysicae ◽

10.5194/angeo-29-1629-2011 ◽

2011 ◽

Vol 29 (9) ◽

pp. 1629-1634 ◽

Cited By ~ 6

Author(s):

K. H. Yearby ◽

M. A. Balikhin ◽

Yu. V. Khotyaintsev ◽

S. N. Walker ◽

V. V. Krasnoselskikh ◽

...

Keyword(s):

Numerical Models ◽

Radiation Belts ◽

High Time Resolution ◽

Wave Interactions ◽

Chorus Waves ◽

Spacecraft Potential ◽

Resolution Electron ◽

Ducted Propagation ◽

Chorus Wave

Abstract. Ducted propagation of whistler waves in the terrestrial magnetosphere-ionosphere system was discussed and studied long before the first in-situ spacecraft measurements. While a number of implicit examples of the existence of ducted propagation have been found, direct observation of ducts has been hampered by the low sampling rates of measurements of the plasma density. The present paper is based on Cluster observations of chorus waves. The ability to use measurements of the spacecraft potential as a proxy for high time resolution electron density measurements is exploited to identify a number of cases when increased chorus wave power, observed within the radiation belts, is observed simultaneously with density enchantments. It is argued that the observation of ducted propagation of chorus implies modification of numerical models for plasma-wave interactions within the radiation belts.

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Solar Corona Investigation by the Coronal Line Photometer at Lomnický Peak

International Astronomical Union Colloquium ◽

10.1017/s0252921100025744 ◽

1994 ◽

Vol 144 ◽

pp. 431-434

Author(s):

M. Minarovjech ◽

M. Rybanský

Keyword(s):

Solar Corona ◽

Time Resolution ◽

Active Regions ◽

High Time ◽

High Time Resolution ◽

List Type ◽

Type Number ◽

Coronal Line ◽

Global Cycle

AbstractThis paper deals with a possibility to use the ground-based method of observation in order to solve basic problems connected with the solar corona research. Namely:1.heating of the solar corona2.course of the global cycle in the corona3.rotation of the solar corona and development of active regions.There is stressed a possibility of high-time resolution of the coronal line photometer at Lomnický Peak coronal station, and use of the latter to obtain crucial observations.

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Periodic Variations in the Coronal Green Line Intensity and their Connection with the White-light Coronal Structures

International Astronomical Union Colloquium ◽

10.1017/s0252921100064484 ◽

2000 ◽

Vol 179 ◽

pp. 197-200

Author(s):

Milan Minarovjech ◽

Milan Rybanský ◽

Vojtech Rušin

Keyword(s):

Time Resolution ◽

White Light ◽

Short Time Scale ◽

High Time Resolution ◽

Green Line ◽

Periodic Intensity ◽

Coronal Green Line ◽

Significant Intensity ◽

Short Time ◽

Coronal Structures

AbstractWe present an analysis of short time-scale intensity variations in the coronal green line as obtained with high time resolution observations. The observed data can be divided into two groups. The first one shows periodic intensity variations with a period of 5 min. the second one does not show any significant intensity variations. We studied the relation between regions of coronal intensity oscillations and the shape of white-light coronal structures. We found that the coronal green-line oscillations occur mainly in regions where open white-light coronal structures are located.

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