PhD in IAGA #6

IAGA has a lot of different scientists working on various topics. In this series of blogs, we introduce some topics that were or are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Dr. Anita Devi completed her postgrad from the Department of Geophysics, Kurukshetra University, India after which she worked for two years as a Geophysicist in TVIPL. She did her Ph.D. from Indian Institute of Technology, Roorkee in 2019. For a brief period of 3 months, she also worked as a Post-Doctoral fellow (SERB-NPDF) at Wadia Institute of Himalayan Geology, India. During her doctoral research, she worked on various electrical and electromagnetic prospecting methods to deciphered resistivity structures. She is currently working as a Scientist at CSIR-NGRI, in magnetotelluric group. 

Her Ph.D. research was focused on 3D (3-Dimensional) individual and joint inversion of magnetotelluric (MT), Radio magnetotelluric and Electrical resistivity tomography (ERT) data. She presented the first 3D resistivity model for Garhwal Himalayan region around Roorkee-Gangotri and Chamoli region. She has worked on all the aspects of Magnetotelluric (acquisition, processing, 3D modelling and inversion). She is interested in delineating the 3D resistivity subsurface structures for exploration and tectonic studies. Her earlier work focuses on the geodynamic studies of Himalayan region. Currently she is working on 3D MT studies of both the Central Indian Tectonic Zone and the Himalaya region. She has published research papers in reputed national and international journals like Journal of Applied Geophysics and Near Surface Geophysics and participated in several International workshops (EMIW, IAGA-IASPEI).

Depth slices of the inverted 3D electrical model of Roorkee-Gangotri profile from Devi et al. 2019 with the letters marking the major resistivity features.

How To... Help with Outreach

In our new series of blogs we want to shine a light on some of the basics that researchers undertake in their day-to-day lives and provide guidance for early-career researchers. There are some tasks that a researcher will never have any official training in but are expected to do as part of their jobs. We hope these blogs make it easier. The first blog in this "How To..." series focuses on outreach. 

Science is fun and interesting! That’s why researchers choose to do the job that they do! But a large part of a researcher's job is communicating new results to the wider scientific and public community – sometimes referred to as ‘outreach’. So here’s a quick ‘How To…’ guide to provide some insight into everything outreach.

What is outreach?

The process of communicating science to others. It usually refers to educating the public in science and other topics they might not encounter in day to day life.

Why do outreach?

It is rewarding and can be a lot of fun. The general public funds a lot of research through taxes and it is a great way to demonstrate why science is important. Also, it is a great way to show your results to others and may allow you to appear on TV or help with a film related to your research (e.g. Jurassic Park!).

How do you do outreach?

Outreach can happen on all scales; it can be as simple as talking to an individual or running an international science festival! However, regardless of the size of the project there are some things you should always remember:

1.    Be age and material appropriate – a 4-year old child will not have the same understanding of the world as their parent. Therefore, we have to tailor the words and activities we use for the situation.

2.    Be engaging – asking people questions or having an activity for participants can help keep the audiences’ attention.

3.    Be organised – it is important to have everything set up and ready to go ahead of time. Think about what materials you will need and how the event will run.

4.    Be ready for questions – people love asking questions back! Make sure you know a bit more than just about the field you work in.

Want to know more?

The best way to become more involved with outreach is to join an existing project in your nearby community. There’s lots of materials out there if you search the internet. There’s also events run through international organisations (e.g. AGU, RAS, EGU etc) which you can join. Take a look at the websites below to be inspired:

https://www.skypeascientist.com/

https://www.societyforscience.org/outreach-and-equity/

http://www.uscscienceoutreach.org/

https://nationalmaglab.org/education/teachers/classroom-outreach-2

https://pintofscience.com/

 

Image Credits: Created using fotor.com

Hannah Rogers has just submitted her PhD thesis at the University of Edinburgh and is a member of the IAGA Social Media team. Her specialism is in investigating regional magnetic fields of Earth at the surface and the core-mantle boundary using mathematical methodologies. You can follow her on Twitter at @Hannah_Rogers94.

PhD in IAGA #5

IAGA has a lot of different scientists working on various topics. In this series of blogs, we will introduce some topics that are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Sarasija Sanaka, is a PhD student working at the Institute of Geophysics Polish Academy of Science, Poland. Her supervisor is Dr. hab. Anne Neska. Sarasija says:

My research is about source effects in Magnetotellurics. Source effects are the inappropriate source signals which lead to distortion in the results, which further leads to misinterpretation of the subsurface electrical structure. My task is to identify and understand the origin of such problematic signals. Such signals are dominant in the high to mid-latitude regions. To recognize source effects, we have considered long-term magnetotelluric data, because they reveal temporal changes which cannot be explained by subsurface conductivity changes.

The above figures represent time-dependent transfer functions at 4000s for Grabnik (GRB) and Suwałki (SUV) stations in Poland.

PhD in IAGA #4

IAGA has a lot of different scientists working on various topics. In this series of blogs, we will introduce some topics that are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Hannah Rogers, a PhD candidate at the University of Edinburgh, says:

In my research, I'm interested in separating the Earth's magnetic field into local regions to better comprehend the core-mantle interactions. Most core flow and magnetic field models are described by spherical harmonics. However, they are not suitable for separation into different regions due to leakage. I instead use spherical Slepian functions to spatially and spectrally separate bandlimited potential fields. Long-lived features of the magnetic field have been guessed to be linked to Large Low Velocity Provinces (LLVPs). They are low seismic velocity regions in the lowermost mantle. My aim is to use the Slepian functions to investigate how LLVPs affect core surface flows over time.

The outer core and lower mantle interactions. The arrows represent the magnetic field lines. Credits : Kay Lancaster

PhD in IAGA #3

IAGA has a lot of different scientists working on various topics. In this series of blogs, we will introduce some topics that are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Samuel Fielding, a PhD candidate at the University of Edinburgh, says:

My research topic is looking at the current forecasting capabilities within the field of space weather, and trying to improve them and find new avenues of research within the field using machine learning. With the large amounts of data being collected on space weather from the many satellites currently in orbit around the Earth or at the L1 Lagrange point, there is a lot of data to train machine learning algorithms on, and the Earth-Sun system is currently not well modelled by current physical models because of the complexity of interactions within the system. This means that the field is a perfect place to explore machine learning models, and it is a very active field with a lot of research on optimising current prediction models. Can these models be optimised further, and looking forwards, is machine learning the right way for us to predict space weather events?

 

False-colour image of a solar eclipse from 21 August 2017. Copyright Miroslay Druckmuller. As published in SciTechDaily, 21 June 2021 and Habbal et al. 2021.

PhD in IAGA #2

IAGA has a lot of different scientists working on various topics. In this series of blogs, we will introduce some topics that are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Shivangi Sharan is a PhD candidate working in the Laboratory of Planetology and Geosciences at Nantes University, France. She says:

My research entails studying the magnetic field of planets, typically Mars and Jupiter, and deciphering information about its interior structure from them. There are internal and external sources of magnetic fields around a planet which can be modeled using Spherical Harmonics. These models then go on to provide us some details about the static and transient fields as well as about the change in field over time.

Radial component of the internal magnetic fields at the surface of the planets. Credit : From a study report for the Keck Institute for Space Studies (KISS) (https://kiss.caltech.edu/final_reports/Magnetic_final_report.pdf) 

PhD in IAGA #1

IAGA has a lot of different scientists working on various topics. In this series of blogs, we will introduce some topics that are being worked on by PhD students. Hopefully this will give a better picture of the work being done in the field and encourage more early career researchers.

Paweł Jujeczko is a PhD candidate working in the Space Research Centre at the Polish Academy of Sciences. He says:

My research topic concerns the physics of Transient Luminous Events (TLEs). For those not familiar with that abbreviation, TLEs are some various phenomena that occur over very powerful thunderclouds (~10 to 100 km above the ground). In my research I model the behaviour of a TLE called "sprite" with a multi-processor code which works within the kinetic plasma theory. I try to model an instability that is possibly present in a plasma of TLE conditions or in simpler words, I try to tell why sprites look like these on the picture here.

Credit : https://apod.nasa.gov/apod/ap191008.html

 

Magnetic Field : Sun

Just like a planetary dynamo generates a magnetic field inside the planet, solar dynamo is responsible for the solar magnetic field. The Sun is composed of plasma, i.e, charged particles, which in motion produce magnetic fields. This field is carried away from the sun towards the planets in all directions by the solar wind, and is called the interplanetary magnetic field (IMF). Two interesting phenomena related to the field are its variation and shape.  

Interplanetary magnetic field extending out from the Sun. Credit: Vallée, J 1998

The solar magnetic field acts as a bar magnet with two poles. These poles are observed to flip regularly every 11 years. This variation is termed as a solar cycle. The solar minimum, when the field is weak, is considered the start of a solar cycle. The sunspots are lowest during this time. Sunspots are dark spots observed on the surface where the magnetic flux is very high (over 0.2 Teslas).

Number of sunspots vs time depicting solar cycles. Credit: ESA/NOAA.

The IMF extending out from the sun with the solar wind travels as a rotating spiral due to the spinning of the sun. This shape is known as the Parker spiral. The sun rotates around every 24 days at the equator and every 35 days at the pole. On average, this is taken to be 27 days and is known as the Carrington rotation.

Image Credit: NASA

                                                  
The solar magnetic field and its related phenomena are active topics of research. There is still a lot to find and understand! 

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Shivangi Sharan is a second year PhD student at the Laboratory of Planetology and Geodynamics in France. Her research focusses on the study of the magnetic field of Mars and to infer its internal structure from it. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

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WDC archive - Preservation of Old data

In 2020, the World Data Centers for Solid Earth Physics and Solar‐Terrestrial Physics (Moscow, Russia) continued the work on the “Preservation of Old Data” project, aimed at digitizing analog data from observatories into electronic documents by in‐line scanning. 

 

 

 

The data of the 8 ionospheric stations (43,500 documents) were transferred to a digital form. This includes the results of a vertical sounding of the ionosphere (tables and graphs of hourly mean values of the ionospheric parameters), measurements of absorption, ionospheric winds, atmospheric radio noise, parameters of electronic density of the ionosphere. 

 

 

Digital documents have been verified and edited. For the data in PDF format, the catalog and metadata have been compiled, a data archive has been formed and published on the website. The data archive for the hourly average values of the elements of the geomagnetic field, recorded by the former USSR observatories from 1957 to the beginning of the 90s, that had been previously fully scanned and translated into PDF files, has undergone verification process and editing. 

In 2020, 82 annual datasets of 4 observatories were checked, edited and added to the archive. Currently the time tables of the 26 observatories containing hourly average values of the elements of the geomagnetic field are ready and located in the WDC archive.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.

IGY by ICH

A thorough insight into the International Geophysical Year (IGY) project from a 60‐year later perspective has been depicted by Y. Lyubovtseva, A. Gvishiani, A. Soloviev et al. in “Sixtieth anniversary of the International Geophysical Year (1957–2017) – contribution of the Soviet Union” published in the History of Geo‐ and Space Sciences journal (https://doi.org/10.5194/hgss‐11‐ 157‐2020). 

The IGY was the most significant international scientific event in geophysical sciences in the history of mankind. This was the largest international experiment that brought together about 300 000 scientists from 67 countries. Well‐planned activity of national and international committees was organized for the first time.

Read also about the "The IGY and Me" blogs published in our last blog here.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.

K index digitization

K index is one of the oldest universal indices of geomagnetic activity that is still being widely used. The multidecadal practice of its application makes it an indispensable source of information for retrospective and historical analysis of solar‐terrestrial interaction for nearly eight Solar cycles. 

Example of range limits of K-index at different observatories. Credit : http://isgi.unistra.fr/what_are_kindices.php 

Most significantly, while studying the historical geomagnetic data, K index datasheets are in most cases more convenient for automated analysis than the analogue magnetograms. World Data Center for Solar‐Terrestrial Physics (Moscow, Russia) collected and digitized the results of the K index determination at 41 geomagnetic observatories of the former USSR for the period from July 1957 to early 1990s. 

This unique historical data collection is valuable for retrospective analysis and studying geomagnetic events in the past as well as for data validation or forecasting. This data collection is now available from the PANGEA data archive (https://doi.org/10.1594/PANGAEA.922233), and the relevant data paper has been published in the ESSD journal: N.Sergeyeva, A.Gvishiani, A.Soloviev, L.Zabarinskaya, T.Krylova, M.Nisilevich, and R.Krasnoperov (2021), Historical K index data collection of Soviet magnetic observatories, 1957–1992, ESSD, https://doi.org/10.5194/essd‐2020‐270.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.

Planetary Magnetic Fields : Gas Giants

Ever wondered how the beautiful auroras we see are formed? You are right, it’s due to the energetic particles carried along with the solar wind from the sun, that enter the magnetic field shield, called the magnetosphere of the planet, interacts there and collects at the poles. Why at the poles? Because that’s how the field lines travel. But it doesn’t just happen on Earth. And it doesn’t just emit visible light spectrum, at least on the outer planets.

Interior models of the giant planets. Image : NASA/Lunar and Planetary Institute

The gas and ice giants of our Solar system - Jupiter, Saturn, Uranus and Neptune - have extremely large magnetic fields and magnetospheres. Their interiors are unlike the interior of the terrestrial planets. They are mostly composed of gases and have a small solid core. Their magnetic fields are similar to that of Earth, i.e, dominantly dipolar, but the magnitudes are much larger than the terrestrial value. 

The interiors of Jupiter and Saturn consist of hydrogen and helium in different forms. Jupiter has the largest magnetic field in the Solar system that is assumed to be generated from the metallic hydrogen in its interior. The magnetosphere is so large that its tail almost reaches Saturn. The metallic hydrogen of Saturn is considered smaller in size comparatively and thus produces a lower magnetic field, but still much larger than Earth’s. The dipole magnetic field axis and the rotation axis almost align.

Magnetic field of the outer planets. Image : Stevenson 2018

The ice giants, Uranus and Neptune, have no metallic hydrogen but have molecular hydrogen and compounds like methane and ammonia in their interior. Uranus has an off-centered field. It rotates on its side due to its large tilt and its magnetic and rotation axes make a 59 degrees angle between them. The magnetic field and magnetosphere of Neptune is similar except that the planet is not as tilted.

Read about the magnetic fields of terrestrial planets here.

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Shivangi Sharan is a second year PhD student at the Laboratory of Planetology and Geodynamics in France. Her research focusses on the study of the magnetic field of Mars and to infer its internal structure from it. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

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Digitization of Kosmos Missions

Geophysical Center of the Russian Academy of Sciences performed digitization of IZMIRAN catalogues containing historical data of magnetic satellite missions Kosmos‐49 (1964) and Kosmos‐321 (1970). 

External view of Kosmos-321 and Kosmos-356 from Krasnoperov et al. 2020.

Totally 17300 measured values are available for Kosmos‐49 mission, covering homogeneously 75% of the Earth's surface between 49° north and south latitude. About 5000 measured values are available for Kosmos‐321 mission, covering homogeneously 94% of the Earth's surface between 71° north and south latitude. 

The mission of Kosmos‐26 and Kosmos‐49 confirmed the possibility of using Earth’s magnetic field data for determination of spacecraft orientation. The obtained geomagnetic data justified the evidence of propagation of magnetic anomalies, associated with the structure and tectonics of the Earth’s crust, to the heights of low‐ orbiting satellites. 

In 2020, these results were presented to the scientific community in the ESSD data paper “Early Soviet satellite magnetic field measurements in the years 1964 and 1970” by Krasnoperov R., Peregoudov D., Lukianova R., Soloviev A., Dzeboev B. (https://doi.org/10.5194/essd‐12‐555‐2020). The value of the presented data is emphasized by the fact that older and publicly available global satellite data on the Earth's magnetic field in digital form for that period are rare and hard to acquire.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.

Planetary Magnetic Fields : Terrestrial Planets

Cutaway views of the interiors of the terrestrial planets reproduced from Solarview. Image : Mulyukova and Bercovici 2021

The four innermost planets of our Solar System - Mercury, Venus, Earth and Mars - are classified as the terrestrial planets due to their similarities in structure. They are composed of metals or rocks and have a solid hard surface.

Starting with our planet Earth, it has the strongest magnetic field among these four. You must have heard that the Earth has a magnet inside it. Well, that’s not entirely right. The convecting motion of metals in the core produces a magnetic field that is similar to the field produced by a bar magnet. To make this dominant dipolar field easier to understand, the field is represented by a magnet inside. But, we also have non-dipolar fields from the core and other sources like the crust and the ionosphere. Equally interesting to study is the change in the magnetic field over time which also tells us that the field changes its polarity. So the compass you are using now will not show the same results to your descendants born after a reversal!

Image : Mouritsen 2015. It shows a representation of the Earth's magnetic field. The geographic and magnetic axes are not aligned but at an angle of about 12 degrees.

The smallest of the planets, Mercury, has a weak core field. The slow rotation of the planet is one of the reasons for its low magnitude. Another is it's not-so-hot core. But the field is still strong enough to have a magnetosphere. More magnetic data from upcoming missions will help to fully understand the planet.

Image : NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington, from results of the early phases of Messenger satellite. It is a depiction of the magnetosphere of Mercury with distortions of magnetic field (blue) from solar winds. 

Mars has been the hot topic lately. It has also had a bunch of satellites orbiting it and landers on it for some time now. So we can say assertively from those observations that it once had an active core field, i.e., a dynamo. It has remnant crustal fields of magnitudes higher than that observed on Earth that interact with the solar winds and produce mini-magnetospheres. So, surely it had a strong dynamo in the past, sometime near 3.7Ga or maybe 4.1Ga ago?

Images : (Coloured) Brain et al. 2015. The solar wind carries with it particles (yellow and dashed lines) that interact with the Martian crustal magnetic fields (orange). (Black and white) Zhang et al. 2008. Schematic of the induced magnetosphere of Venus.

Lastly, we have Venus. You can feel a little sad for the planet because no one talks much about it when it comes to magnetic fields. That’s because there has been no evidence of any core field there. But don't feel too sad, NASA and ESA have selected a total of three future missions to visit the planet!

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Shivangi Sharan is a second year PhD student at the Laboratory of Planetology and Geodynamics in France. Her research focusses on the study of the magnetic field of Mars and to infer its internal structure from it. She is an active member of the IAGA Blog Team and can be contacted via e-mail here.

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ICH sessions in IAGA-IASPEI 2021!!

ICH has co‐organized two sessions as part of the upcoming 2021 IAGA‐IASPEI Joint Scientific Assembly : 

“Analogue Data for Future: Preservation and Present‐Day Utilization of Instrumental Historical Data in Geosciences” (together with IASPEI) 

“Remarkable geomagnetic events and indices: Derivation, history, and applications for space weather” (together with Div. IV, V and ICSW)

Do attend the sessions for the submissions from both IASPEI and IAGA communities covering all aspects of historical research in geophysics and involving historical data archives.

Contributed by the Chair of the Interdivisional Commission on History, Dr. Anatoly Soloviev, from the Geophysical Center, Russian Academy of Sciences, Moscow. The Commission encourages historical geophysical research and preservation of IAGA's history.