| Title | Quality issues and proposals for improvements in the baseline adaption at geomagnetic observatories |
| Author | Igor Mandić |
| Mentor(s) | Monika Korte
|
| Abstract | Data provided by geomagnetic observatories are fundamental in geomagnetic field studies and are widely used in other applications. Often they are combined with satellite and ground survey data. Unfortunately, the definitive observatory data are only available with a time lag ranging from several months up to more than a year. The main reason for this lag is the annual production of the final calibrated values, i.e. baselines that are used to correct preliminary data from continuously recording instruments at the observatory. To increase the prompt availability of calibrated observatory data, INTERMAGNET has recently started to distribute quasi-definitive data. These data are calibrated with temporary baselines and reported much faster than annual definitive data. In this thesis it is shown that the preparation of definitive geomagnetic data, i.e. definitive calibration values, is possible within a calendar year for most observatories of the INTERMAGNET type. An original method for prompt and automatic estimation of temporary quasi-definitive baselines is presented. Results of this baseline calculation obtained in a mostly automatic manner and comparisons with the baselines reported on INTERMAGNET DVDs for the 2009-2011 period are presented. The high quality of definitive and quasi-definitive baselines obtained by the new method indicate its suitability for data processing for nearly fully automatic observatories when automated absolute instruments will be deployed at remote sites. However, the automatic instruments show a larger scatter and an automated processing protocol should be robust to outliers. Data from Lonjsko Polje observatory are used to simulate datasets from an automated absolute instrument producing 24 observations per day. Results of these tests also confirmed robustness and reliability of the proposed method. |
| Parallel title (Croatian) | Problemi kvalitete i prijedlozi za poboljšanje prilagodbe baznih linija u geomagnetskim opservatorijima |
| Committee Members | Giuliana Verbanac (committee chairperson)
Monika Korte (committee member)
Mario Brkić (committee member)
Davorka Herak (committee member)
Snježana Markušić (committee member)
|
| Granter | University of Zagreb
Faculty of Science |
| Lower level organizational units | Department of Geophysics |
| Place | Zagreb |
| State | Croatia |
| Scientific field, discipline, subdiscipline | NATURAL SCIENCES
Geophysics
Other Geographic Disciplines
|
| UDK | 53
NATURAL SCIENCES
Physics |
| Study programme type | university |
| Study level | postgraduate |
| Study programme | Physics |
| Academic title abbreviation | dr. sc. |
| Genre | doctoral thesis |
| Language | English |
| Defense date | 2017-11-29 |
| Promoted date | 2017-11-29 |
| Parallel abstract (Croatian) | Podaci geomagnetskih opservatorija čine temelj u izučavanju geomagnetskog polja, nalaze široku primjenu u drugim geofizičkim disciplinama te se koriste za ostale primijenjene svrhe. Često se koriste zajedno sa satelitskim podacima i podacima terenskih izmjera. Nažalost, definitivni podaci geomagnetskih opservatorija su dostupni sa zakašnjenjem u periodu od nekoliko mjeseci, pa čak i više od godinu dana. Glavni razlog tog kašnjenja jest godišnja produkcija konačnih (definitivnih) kalibracijskih vrijednosti, tj. baznih linija koje se koriste za korekciju preliminarnih podataka s instrumenata koji kontinuirano mjere u geomagnetskim opservatorijima. U svrhu poboljšanja dostupnosti kalibriranih magnetskih podataka, u novije vrijeme INTERMAGNET je počeo publicirati kvazi-definitivne podatke. Ovi podaci su kalibrirani s privremenim baznim linijama te se izdaju puno brže nego godišnji definitivni podaci. U ovoj disertaciji je prikazano da je priprema definitivnih geomagnetskih podataka, tj. definitivnih kalibracijskih vrijednosti moguća unutar godine dana za većinu opservatorija mreže INTERMAGNET. Predložena metoda je također pogodna za promptnu i automatsku procjenu privremenih, kvazi-definitivnih baznih linija. Rezultati kalkulacije baznih linija predloženom metodom, dobivenih skoro u potpunosti automatskim putem, uspoređeni su s baznim linijama publiciranim na INTERMAGNET-ovim DVD-ima za period 2009-2011. Visoka kvaliteta definitivnih i kvazi-definitivnih baznih linija dobivenih novom metodom ukazuje da je predložena metoda prikladna za automatsku obradu podataka kada u potpuno automatiziranim opservatorijima (na udaljenim lokacijama) budu instalirani automatski apsolutni instrumenti. S druge strane, automatski instrumenti pokazuju veća raspršenja i pogreške u mjerenjima te bi iz tog razloga protokol za automatsku obradu podataka trebao biti robustan. Podaci iz opservatorija Lonjsko polje korišteni su kako bi se simulirali podatkovni setovi automatskog apsolutnog instrumenta koji vrši 24 opažanja na dan. Rezultati ovih testova su također potvrdili robusnost i pouzdanost predložene metode. |
| Parallel keywords (Croatian) | Geomagnetic observations Definitive data Quasi-definitive data Baseline fitting Data processing Geomagnetski opservatorij Apsolutna mjerenja Variometri Prilagodba baznih linija |
| Extent | 101 str. ; 30 cm |
| Version | accepted version |
| Resource type | text |
| Access condition | Open access |
| Terms of use |  |
| Note | accepted version |
| URN:NBN | https://urn.nsk.hr/urn:nbn:hr:217:135089 |
| Repository | https://repozitorij.pmf.unizg.hr |
