Reliable real-time Polar Cap (PC) indices for space weather monitoring and forecasts

The Polar Cap (PC) indices were approved by the International Association for Geomagnetism and Aeromony (IAGA) by Resolution No. 3 (2013) noting that “IAGA … recommends use of the PC index by the international scientific community in its near-real time and definitive forms”. PC indices were made available in 2014 at the web portal http://pcindex.org holding near-real time as well as final index values. The near-real time PC index values are not permanently available. However, analyses of indices on basis of occasional downloads have detected differences between near-real time and final PC indices of up to 3.65 mV/m (Stauning, 2018b, Ann Geophys, 36, 621–631). At such differences, one or the other index may indicate (or hide) strong geomagnetic activity without justification in the actual conditions. The present work has disclosed the cause of observed large differences between real-time and final PC index values in the IAGA-endorsed versions. In addition, anticipated differences are derived on a general basis from the available basic magnetic data by using the index calculation procedures and calibration constants provided by the PC index suppliers. It is shown that corresponding or even larger anomalies are expected to be common during moderate to strong magnetic activity where the near-real time PC indices might otherwise prove very useful for space weather monitoring, e.g., for power grid protection. An alternative real-time PC index derivation scheme described here reduces the excessive differences between real-time and final PC index values by an order of magnitude.

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Comment on “Identification of the IMF sector structure in near-real time by ground magnetic data” by Janzhura and Troshichev (2011)

Annales Geophysicae ◽

10.5194/angeo-39-369-2021 ◽

2021 ◽

Vol 39 (2) ◽

pp. 369-377

Author(s):

Peter Stauning

Keyword(s):

Solar Wind ◽

Real Time ◽

International Association ◽

Magnetic Data ◽

Reference Level ◽

Sector Structure ◽

Polar Cap ◽

Ground Magnetic ◽

The Imf

Abstract. The only published description of the solar wind sector (SS) term used for the reference level in the post-event and real-time derivation of the Polar Cap (PC) indices, PCN (Polar Cap North) and PCS (Polar Cap South), in the version endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) is found in the commented publication, Janzhura and Troshichev: Identification of the IMF sector structure in near-real time by ground magnetic data, Annales Geophysicae, 29, 1491–1500, 2011. Actually, the publication has served as a basis for the index endorsement by IAGA in 2013. However, neither the illustrations nor the results presented there have been derived by the specified near real-time method. Figures 1, 6, 7, and 8 display values derived by post-event calculations based on daily medians smoothed over 7 d centred on the day of interest. Figures 2, 3, and 4 display observed values smoothed over 7 d, while the remaining Fig. 5 displays averages over 4 months. In summary, there are strong disagreements between indications in the title, abstract, and statements in the text compared to the actual results and their illustrations.

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Identification of the IMF sector structure in near-real time by ground magnetic data

Annales Geophysicae ◽

10.5194/angeo-29-1491-2011 ◽

2011 ◽

Vol 29 (8) ◽

pp. 1491-1500 ◽

Cited By ~ 10

Author(s):

A. S. Janzhura ◽

O. A. Troshichev

Keyword(s):

Real Time ◽

Magnetic Activity ◽

Magnetic Data ◽

Sector Structure ◽

Polar Cap ◽

Simple Method ◽

Interpolation Procedure ◽

Time Regime ◽

Ground Magnetic ◽

Good Agreement

Abstract. A method is proposed to determine in near-real time the interplanetary magnetic field (IMF) sector structure (SS) effect on geomagnetic data from polar cap stations. To separate the SS effect, whose polarity is invariant within an interval from some days to 2 weeks, from the disturbed solar wind effects with periodicity from minutes to hours, the daily median values of geomagnetic H (or D) component are estimated. Then the median values for 9 days preceding the current day are subjected to 3-days running averages and the interpolation procedure is applied to these smoothed averages. Comparisons of the sector structure reconstructed from the ground magnetic data with the actual variations of the GSM IMF By component measured onboard the ACE spacecraft in the summer months of 1990 and 2001 demonstrate their good agreement with coefficient of correlation R=0.96–0.97 for the H-component and R=0.93–0.95 for the D-component. The proposed simple method makes possible identification of the SS effect in the same near real-time regime as the derivation of the quiet daily curve and as level of reference for the polar cap magnetic disturbances in the calculation of the polar cap magnetic activity PC index.

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Unreliable IAGA-endorsed Polar Cap (PC) index series and a different approach

10.5194/egusphere-egu2020-10195 ◽

2020 ◽

Author(s):

Peter Stauning

Keyword(s):

Solar Wind ◽

Real Time ◽

Space Weather ◽

Magnetic Data ◽

Reference Level ◽

Sector Structure ◽

Reference Levels ◽

Polar Cap ◽

The Real ◽

Critical Note

The Polar Cap (PC) indices are derived from the magnetic variations generated by the transpolar convection of magnetospheric plasma and embedded magnetic fields driven by the interaction with the solar wind. The PC indices are potentially very useful for Space Weather monitoring and forecasts and for related research. However, the PC index series in the near-real time and final versions endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) have been proven unreliable (Stauning, 2013, 2015, 2018a,b,c, 2020). Both versions include solar wind sector (SWS) effects in the calculation of the reference levels from which magnetic disturbances are measured. The SWS effects are caused by current systems in the dayside Cusp region related to the Y-component, BY, of the Interplanetary Magnetic Field (IMF). However, the IAGA-endorsed handling of SWS effects may generate unfounded PC index changes of up to 3 mV/m at the nightside away from the Cusp. For the real-time PCN and PCS indices, their cubic spline-based reference level construction may cause additional unjustified index excursions of more than 3 mV/m with respect to the corresponding final index values. Noting that PC index values above 2 mV/m indicate geomagnetic storm conditions, such unjustified contributions are considered to invalidate the IAGA-endorsed PC index series. The presentation shall include a description of alternative derivation methods shown to provide more consistent index reference levels for both final and real-time PC indices, to reduce their unfounded excursions, and to significantly increase their reliability (Stauning, 2016, 2018b,c).References. Stauning, P. (2020): The Polar Cap (PC) index: invalid index series and a different approach. Space Weather, 2020SW002442 (submitted).Stauning, P. (2013). Comments on quiet daily variation derivation in &#8220;Identification of the IMF sector structure in near-real time by ground magnetic data&#8221; by Janzhura and Troshichev (2011). Annales Geophysicae, 31, 1221-1225. https://doi.org/10.5194/angeo-31-1221-2013 .Stauning, P. (2015). A critical note on the IAGA-endorsed Polar Cap index procedure: effects of solar wind sector structure and reverse polar convection. Annales Geophysicae, 33, 1443-1455. https://doi.org/10.5194/angeo-33-1443-2015 .Stauning, P. (2016). The Polar Cap (PC) Index.: Derivation Procedures and Quality Control. DMI Scientific Report SR-16-22. Available at: https://www.dmi.dk/fileadmin/user_upload/Rapporter/TR/2016/SR-16-22-PCindex.pdf .Stauning, P. (2018a). A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values. Annales Geophysicae, 36, 621&#8211;631. https://doi.org/10.5194/angeo-36-621-2018 .Stauning, P. (2018b): Multi-station basis for Polar Cap (PC) indices: ensuring credibility and operational reliability. Journal of Space Weather and Space Climate, 8, A07. https://doi.org/10.1051/swsc/2017036 .Stauning, P. (2018c). Reliable Polar Cap (PC) indices for space weather monitoring and forecast

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Comment on Identification of the IMF sector structure in near-real time by ground magnetic data by Janzhura and Troshichev (2011)

10.5194/angeo-2020-53 ◽

2020 ◽

Author(s):

Peter Stauning

Keyword(s):

Solar Wind ◽

Real Time ◽

International Association ◽

Magnetic Data ◽

Reference Level ◽

Sector Structure ◽

Polar Cap ◽

Ground Magnetic ◽

The Imf

Abstract. The only published description of the solar wind sector (SS) term used for the reference level in the post-event and real-time derivation of the Polar Cap (PC) indices, PCN (North) and PCS (South), in the version endorsed by the International Association for Geomagnetism and Aeronomy (IAGA) is found in the commented publication, Janzhura and Troshichev (2011): Identification of the IMF sector structure in near-real time by ground magnetic data, Annales Geophysicae, 29, 1491–1500. Actually, the publication has served as basis for the index endorsement by IAGA in 2013. However, neither the illustrations nor the results presented there have been derived by the specified near-real time method. Figs. 1, 6, 7, and 8 display values derived by post-event calculations based on daily medians smoothed over 7 days centred on the day of interest. Figs. 2, 3, and 4 display observed values smoothed over 7 days, while the remaining Fig. 5 displays averages over 4 months. In summary, there are strong disagreements between indications in the title, abstract, and statements in the text compared to the actual results and their illustrations.

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A critical note on the IAGA-endorsed Polar Cap (PC) indices: excessive excursions in the real-time index values

Annales Geophysicae ◽

10.5194/angeo-36-621-2018 ◽

2018 ◽

Vol 36 (2) ◽

pp. 621-631 ◽

Cited By ~ 3

Author(s):

Peter Stauning

Keyword(s):

Real Time ◽

Present Note ◽

International Association ◽

Polar Cap ◽

Storm Activity ◽

Strong Magnetic Storm ◽

The Real ◽

Critical Note ◽

Derivation Procedure ◽

Modelling And Forecasting

Abstract. The Polar Cap (PC) indices were approved by the International Association for Geomagnetism and Aeronomy (IAGA) in 2013 and made available at the web portal http://pcindex.org holding prompt (real-time) as well as archival index values. The present note provides the first reported examination of the validity of the IAGA-endorsed method to generate real-time PC index values. It is demonstrated that features of the derivation procedure defined by Janzhura and Troshichev (2011) may cause considerable excursions in the real-time PC index values compared to the final index values. In examples based on occasional downloads of index values, the differences between real-time and final values of PC indices were found to exceed 3 mV m−1, which is a magnitude level that may indicate (or hide) strong magnetic storm activity. Keywords. Magnetospheric physics (solar wind–magnetosphere interactions; polar cap phenomena) – ionosphere (modelling and forecasting)

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Comments on quiet daily variation derivation in "Identification of the IMF sector structure in near-real time by ground magnetic data" by Janzhura and Troshichev (2011)

Annales Geophysicae ◽

10.5194/angeo-31-1221-2013 ◽

2013 ◽

Vol 31 (7) ◽

pp. 1221-1225 ◽

Cited By ~ 7

Author(s):

P. Stauning

Keyword(s):

Solar Wind ◽

Real Time ◽

Daily Variation ◽

Magnetic Data ◽

Sector Structure ◽

Polar Cap ◽

Ground Magnetic ◽

The Imf

Abstract. The description presented in the paper of the relations of the solar wind sector structure to the derivation of the quiet daily variation (QDC) in polar magnetic recordings used for calculation of polar cap (PC) indices is found to be unclear and not properly justified. The presented example on inclusion of a solar sector term in an actual QDC series is found to be questionable even on the authors' premises.

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Near-surface real-time seismic imaging using parsimonious interferometry

Scientific Reports ◽

10.1038/s41598-021-86531-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sherif M. Hanafy ◽

Hussein Hoteit ◽

Jing Li ◽

Gerard T. Schuster

Keyword(s):

Fluid Flow ◽

Real Time ◽

Temporal Resolution ◽

Seismic Imaging ◽

Time Lapse ◽

Rock Properties ◽

Recording Time ◽

Near Surface ◽

Arrival Times ◽

Order Of Magnitude

AbstractResults are presented for real-time seismic imaging of subsurface fluid flow by parsimonious refraction and surface-wave interferometry. Each subsurface velocity image inverted from time-lapse seismic data only requires several minutes of recording time, which is less than the time-scale of the fluid-induced changes in the rock properties. In this sense this is real-time imaging. The images are P-velocity tomograms inverted from the first-arrival times and the S-velocity tomograms inverted from dispersion curves. Compared to conventional seismic imaging, parsimonious interferometry reduces the recording time and increases the temporal resolution of time-lapse seismic images by more than an order-of-magnitude. In our seismic experiment, we recorded 90 sparse data sets over 4.5 h while injecting 12-tons of water into a sand dune. Results show that the percolation of water is mostly along layered boundaries down to a depth of a few meters, which is consistent with our 3D computational fluid flow simulations and laboratory experiments. The significance of parsimonious interferometry is that it provides more than an order-of-magnitude increase of temporal resolution in time-lapse seismic imaging. We believe that real-time seismic imaging will have important applications for non-destructive characterization in environmental, biomedical, and subsurface imaging.

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Development of the Cloud-Based Magnetic Data Acquisition System for Real Time Geomagnetic Monitoring

Journal of Physics Conference Series ◽

10.1088/1742-6596/1768/1/012017 ◽

2021 ◽

Vol 1768 (1) ◽

pp. 012017

Author(s):

K Burhanudin ◽

M H Jusoh ◽

Z I Abdul Latiff ◽

M S Suaimi ◽

Z Ibrahim ◽

...

Keyword(s):

Data Acquisition ◽

Real Time ◽

Data Acquisition System ◽

Acquisition System ◽

Magnetic Data

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Space weather challenges of the polar cap ionosphere

Journal of Space Weather and Space Climate ◽

10.1051/swsc/2013025 ◽

2013 ◽

Vol 3 ◽

pp. A02 ◽

Cited By ~ 69

Author(s):

Jøran Moen ◽

Kjellmar Oksavik ◽

Lucilla Alfonsi ◽

Yvonne Daabakk ◽

Vineenzo Romano ◽

...

Keyword(s):

Space Weather ◽

Polar Cap

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The electronic Space Weather upper atmosphere (eSWua) project at INGV: advancements and state of the art

Annales Geophysicae ◽

10.5194/angeo-26-345-2008 ◽

2008 ◽

Vol 26 (2) ◽

pp. 345-351 ◽

Cited By ~ 31

Author(s):

V. Romano ◽

S. Pau ◽

M. Pezzopane ◽

E. Zuccheretti ◽

B. Zolesi ◽

...

Keyword(s):

Real Time ◽

Space Weather ◽

State Of The Art ◽

Upper Atmosphere ◽

Software System ◽

General Description ◽

Data Archiving ◽

Web Tools ◽

Technical Features ◽

Technological Community

Abstract. The eSWua project is based on measurements performed by all the instruments installed by the upper atmosphere physics group of the Istituto Nazionale di Geofisica e Vulcanologia, Italy and on all the related studies. The aim is the realization of a hardware-software system to standardize historical and real-time observations for different instruments. An interactive Web site, supported by a well organized database, can be a powerful tool for the scientific and technological community in the field of telecommunications and space weather. The most common and useful database type for our purposes is the relational one, in which data are organized in tables for petabytes data archiving and the complete flexibility in data retrieving. The project started in June 2005 and will last till August 2007. In the first phase the major effort has been focused on the design of hardware and database architecture. The first two databases related to the DPS4 digisonde and GISTM measurements are complete concerning populating, tests and output procedures. Details on the structure and Web tools concerning these two databases are presented, as well as the general description of the project and technical features.

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