Tomislav Bašić

University of Zagreb

Radar satellite altimetry is one of the basic satellite measurement techniques intended primarily for solving global geodetic tasks by means of radar measurements from satellites toward the Earth. Satellite altimetry ensures the collection of high precision global data of uniform accuracy on sea level, which enables monitoring of the geophysical ch...

Bathymetry underpins all marine and ocean research. It is common knowledge that there is a global deficit of high-resolution bathymetry based on modern acoustic techniques. Satellite altimetry enabled modeling of the global seafloor topography and revealed new morphological features in the unmapped areas of the oceans and seas. This chapter gives a...

Developments in sensor technology called Synthetic Antenna Radar (SAR) and associated data processing software have helped satellite radar interferometry (InSAR), a method that uses multiple SAR images of the same area collected from satellites, to become a widely used method for estimating soil deformation as well as other geophysical processes, b...

Promjene globalnih ili nacionalnih geodetskih referentnih koordinatnih sustava, koje uključuju i promjene geodetskih datuma, događaju se rijetko i čine jednu od najzahtjevnijih i najsloženijih operacija u geodeziji, čije se posljedice protežu i na druge struke, korisnike različitih vrsta prostornih podataka. Za korektnu i profesionalno učinkovitu u...

The primary objective of the 1-cm geoid experiment in Colorado (USA) is to compare the numerous geoid computation methods used by different groups around the world. This is intended to lay the foundations for tuning computation methods to achieve the sought after 1-cm accuracy, and also evaluate how this accuracy may be robustly assessed. In this e...

At the very end of the year 2020, at 29th of December, hazard earthquake of M=6.2 hit near Petrinja, at NW of Croatia. Earthquake have been felt in a circumstance of a 400 kilometers, leaving in an epicenter vicinity inconceivable damage, devastated towns and obstructed lives. In order to obtain the first emergency crisis numbers over the impact of...

Bathymetric models representing the topography of the seafloor are an important parameter in almost all maritime related research. Traditional bathymetric shipborne or airborne surveys are cost and/or time consuming, and access to the measured data is mostly limited or expensive. Alternative bathymetric data sources for marine researchers are publi...

The precision of geodetic measurements is reliable as much as the reference on which the measurements relies on. From the aspect of todays' most used geodetic method, the GNSS measurements, its reference is defined through a national reference frame established with corresponding reference stations. Hazardous earthquake of M=6.2 occurred in NW Croa...

This paper studies the contribution of airborne gravity data to improvement of gravimetric geoid modelling across the mountainous area in Colorado, USA. First, airborne gravity data was processed, filtered, and downward-continued. Then, three gravity anomaly grids were prepared; the first grid only from the terrestrial gravity data, the second grid...

Radar satellite altimetry has revolutionized our understanding of the Earth’s sea-level shape and its change over time, monitoring of the natural and human-induced water cycle, marine gravity computations, seafloor relief (bathymetry) reconstruction, tectonics, water mass balance change monitoring, etc., thus providing significant impact in geodesy...

At the very end of the year 2020, on 29 December, a hazardous earthquake of Mw = 6.2 hit the area of Petrinja and its surroundings, in the NW of Croatia. The earthquake was felt across the area of 400 km, leaving an inconceivable damage in the vicinity of the epicenter, devastated towns and ruined lives. In order to map the spreading of earthquake...

Prezentacija sadrži predavanja na hrvatskom jeziku koja je autor kao nositelj predmeta Državna izmjera, držao dugi niz godina na Preddiplomskom studiju Geodezije i geoinformatike Geodetskog fakulteta Sveučilišta u Zagrebu, Hrvatska. (The presentation contains lectures in the Croatian language, which the author, as the holder of the course (Geodeti...

Ice-sheet mass balance and ice behaviour have been effectively monitored remotely by space-borne laser ranging technology, i.e. satellite laser altimetry, and/or satellite gravimetry. ICESat mission launched in 2003 has pioneered laser altimetry providing a large amount of elevation data related to ice sheet change with high spatial and temporal re...

Prezentacija sadrži predavanja na hrvatskom jeziku koja je autor kao nositelj predmeta Geodetski referentni okviri, držao dugi niz godina na Preddiplomskom studiju Geodezije i geoinformatike Geodetskog fakulteta Sveučilišta u Zagrebu, Hrvatska. (The presentation contains lectures in the Croatian language, which the author, as the holder of the cour...

Prezentacija sadrži predavanja na hrvatskom jeziku iz kolegija Fizikalna geodezija, koja je autor dugi niz godina držao na Diplomskom studiju Geodezije i geoinformatike Geodetskog fakulteta Sveučilišta u Zagrebu, Hrvatska. / This presentation contains lectures in the Croatian language from the course Physical Geodesy, which the author held for many...

Prezentacija sadrži predavanja na hrvatskom jeziku iz kolegija Geofizička geodezija, koja je autor dugi niz godina držao na Diplomskom studiju Geodezije i geoinformatike Geodetskog fakulteta Sveučilišta u Zagrebu, Hrvatska. / This presentation contains lectures in the Croatian language from the course Geophysical Geodesy, which the author held for...

The hardware of new-generation smartphones enables navigation, positioning and surveying (NPS) using Global Navigation Satellite Systems (GNSS). Moreover, unprecedented progress has been made in the last few years related to the accuracy and reliability of smartphone NPS giving three significant changes: (1) accessing raw code and carrier GNSS meas...

Sažetak. Promjene geodetskih referentnih koordinatnih sustava, koje uključuju i promjene geodetskih datuma, čine jednu od najzahtjevnijih i najsloženijih geodetskih operacija, pri čemu jedan od većih tehničkih izazova predstavlja pružanje učinkovitih metoda međudatumskih transformacija korisnicima prostornih podataka. Zato je za obavljanje kvalitet...

Different space-borne geodetic observation methods combined with in-situ measurements enable resolving the single-point vertical land motion (VLM) and/or the VLM of an area. Continuous Global Navigation Satellite System (GNSS) measurements can solely provide very precise VLM trends at specific sites. VLM area monitoring can be performed by Interfer...

Popravak kompasa je kut koji u točki na karti definira projekcija magnetskog meridijana točke s ordinatom kartografskog projekcijskog sustava, a jednak je razlici magnetske deklinacije i konvergencije meridijana. U praksi topografsko-geodetske pripreme i osiguranja primjenjuje se tzv. radni popravak kompasa, u kojemu se deklinacija sastoji od dnevn...

Prezentacija daje status-report Globalnog geodetskog opažačkog sustava GGOS, uključujući i kratki prikaz važnijih IAG-servisa, a održana je 21. veljače 2020. godine u okviru kontrolirane izobrazbe putem Interneta (e-learning) "Besplatni izvori geodetskih i geoinformatičkih podataka i softvera te njihova primjena" u okviru programa cjeoživotnog obra...

Sažetak. Promjene globalnih ili nacionalnih geodetskih referentnih koordinatnih sustava, koje uključuju i promjene geodetskih datuma, događaju se rijetko i čine jednu od najzahtjevnijih i najsloženijih operacija u geodeziji, čije se posljedice logično protežu i na druge struke koje koriste različite vrste prostornih podataka. Razmatrajući te promje...

Prezentacija koja daje status report globalnih navigacijskig satelitskih sutava (GPS, GLONASS, Galileo i BeiDou), kratki prikaz proširenih (Augmented) satelitskih sustava kao i hrvatskog nacionalnog sustava CROPOS, je održana u okviru radionice "Praktični primjeri naknadne obrade multi-GNSS mjerenja otvorenim i komercijalnim programima" 31. siječnj...

Predavanje je posvećeno životu i znanstvenim ostvarenjima CLGE geodeta godine 2019., Loránd (Roland) Eötvös-a, a održano je 17. prosinca 2019 u okviru svečane sjednice Hrvatske komore ovlaštenih inženjera geodezije (HKOIG). The lecture is dedicated to the life and the remarkable achievements of the CLGE Surveyor of the Year 2019, Loránd (Roland) E...

Program Europske svemirske agencije, Copernicus, temelji se na globalnim satelitskim i terestričkim mjerenjima koja su najčešće dostupna gotovo u realnom vremenu. Time je omogućeno praćenje geofizičkih i drugih procesa na Zemlji te održivo upravljanje okolišem. Posebna odlika Programa otvoreni je pristup (gotovo) svim podacima uz regulaciju propisi...

Tides have largest impact on gravity measurements compared to all other environmental effects. They are a direct result of the gravitational forces of the planetary bodies, mainly the Moon and the Sun. The magnitude of tidal effects depends on the relative position of planetary bodies around the Earth and can be computed from the astronomical ephem...

In this presentation, made on the occasion of 100 years of the death of the world famous Earth scientist Loránd Eötvös, an overview of gravimetry and geoid modelling in Croatia was shown, with end view on Eötvös's influence on gravity and magnetic field research in Croatia.

OPEN ACCESS ARTICLE ON LINK: http://geofizika-journal.gfz.hr/vol_36/No1/36-1_Varga_et_al.pdf High-resolution digital elevation models (DEMs) have become available in the last decade. They are used in geodesy and geophysics as the main data for modeling of topographic mass effects included in gravimetric and gradiometric measurements. In modeling...

One of the main challenges in physical geodesy today is achieving the 1-centimeter gravimetric quasi-geoid model, since a model of such accuracy could be used in the definition and realization of the height reference frame. One of the main obstacles in this challenge is the lack of terrestrial gravity data or its uneven distribution. Therefore, the...

Trgovanje prostornim informacijama i pružanje usluga povezanih s prostornim informacijama jedan su od osnovnih segmenata gospodarstva neke države. Odnos tržišnih rezultata tog segmenta i ekonomskog stanja nekog područja duboko je isprepleten - pozitivni tržišni rezultati u trgovanju prostornim informacijama najčešće su posljedica ekonomskog boljitk...

The existing multi-mission altimeter observation system meets most of the requirements for monitoring of the absolute sea level and its change over time. However, with the increasing number of the studies on the impact of the sea level rise in coastal areas, a special attention should be paid on reevaluating and improving the absolute sea level mod...

Finding a caverns, pits, and cavities in the Earth's interior is a special challenge both in scientific and technical sense, especially in planning and performing large engineering projects such as highways. Gravity measurements contribute to such geophysical investigations giving the insight to the Earth's interior and supporting the project monit...

In this study results will be presented on the numerical experiments and comparisons of two regional geoid modelling approaches: Remove-Compute-Restore (RCR) and Least Squares Modification of Stokes' Formula with Additive Corrections (LSMSA, also known as KTH). While RCR has been used for few decades, LSMSA approach has gained wide popularity in th...

Ova prezentacija bavi se dualizmom geodezije odnosno njenom pripadnošću dvama područjima: tehničkom (inženjerskom) i prirodnom (geoznanstvenom), što je svakako prednost koju treba iskoristiti za budućnost geodetske znanosti i struke. This presentation deals with the dualism of geodesy and its affiliation in two areas: technical (engineering) and n...

Models of geomorphometric parameters and drainage networks are widely used in many scientific and civilian branches and activities. They are created using the Earth’s land surface data, which are today mostly represented by digital elevation models (DEMs). The main objective of this study is to create models of slope, aspect, and drainage networks...

In the last 200 years, various definitions of the geoid have been given. One of the given definitions is that it is the surface of constant potential W_0. The term geoid is used synonymously for few similar surfaces (such as quasi-geoid or hybrid quasi-geoid), and this depends on particular scientific or practical application. One of its main appli...

Topographic masses are known to have a significant effect in regional geoid modeling. In fact, many authors have emphasized that short wavelengths filtering of gravity signal is crucial in recovering geoid undulations from gravity data. Digital elevation (DEM) and bathymetric models (DBM) are data sources for computation of topographic effects whic...

The presentation gives a brief overview of computing geoid surface in the Republic of Croatia from 1992 until today (2018), including the most important doctoral thesis published in connection with the present research.

In this paper the accuracy of 6 spatial interpolation methods on geoid grid models are tested and compared: Inverse Distance Weighting, Kriging, Minimum Curvature, Natural Neighbour, Radial Basis Function and Moving Average. Grid models are derived from three global geopotential models: EGM2008, EIGEN-6C4 and GECO. Totally 18 geoid models in forms...

The registers of the accurate and accessible digital maritime boundaries, with defined territorial claims and property rights, are of the vital importance for the protection of natural resources and development of the economy of each country. Such registers that allow defining, visualising, recording and managing the rights in marine space can be r...

A rise of a global mean sea level recorded during the 20th and 21st century may have significant influence onto the densely populated low-lying coastal regions. The global sea level rise rates at around 3.3 mm a year. Recent studies detected the acceleration of the sea level rise during the last two centuries both from the satellite altimeter and t...

Radarska satelitska altimetrija metoda je prikupljanja globalnih visoko-preciznih podataka o razini mora u odnosu na odabrani geocentrični referentni okvir. Opažanja satelitskom altimetrijom omogućuju određivanje oblika i veličine Zemlje te računanje Zemljina polja ubrzanja sile teže što su i osnovne geodetske zadaće zadane definicijom geodezije. M...

Radar satellite altimetry is a method that enables obtaining the global high-precision sea level data related to desired geocentric reference frame. Satellite altimeter observations enable efficient solving of the main geodetic tasks addressed by the definition of geodesy, which include measuring the Earth’s size and shape as well as the determinat...

The aim of spatial data infrastructure and spatial data registers is to enable efficient use of systematized spatial data, associated metadata, and tools for data processing and analysis. Traditionally, spatial data registers have been developed to enable land registration, i.e. recording the property rights, their ownership and transfer, and to do...

Fundamental task of geodetic reference systems is to provide horizontal and vertical position with highest accuracy. Conceptually and practically, one of the main issues of 30 cadastre is definition and realization of height reference system. Nowadays, accuracy requirements together with the profitability and homogeneity of the coordinates are grea...

The changes of the biosphere caused by the natural resources management and environment control are driving the short-term and long-term changes of the land cover and land use. Understanding the land cover and land use change enables the analyses of economic and social activities of particular areas, as well as the effective implementation of susta...

Vertical coordinates are the basic component of 30 cadastre, but so far they are rarely discussed during conceptual designing and solution proposal of 30 cadastre. The main reason for that is routine determination of vertical coordinates during field work. However, during the realization 30 cadastre appear many theoretical and practical problems. S...

The main scope of the GEOMED2 project is the determination of a high-accuracy and high-resolution geoid model for the Mediterranean Sea using land and marine gravity data and the more recent Global Geopotential Models, those based on GOCE/GRACE data. The processing methodology is based on the well-known remove-compute-restore procedure and both sto...

The GEOMED2 project has been set up in order to compute an updated estimate of the geoid in the Mediterranean area. In this work, the geoid computation based on gravity data collected in the area 29o<lat.<48o -10o<lon.<41o, covering the entire Mediterranean basin, is presented. Outlier rejection and data homogenization have been carefully performed...

Satellite based global gravity field models represent Earth's long-wavelength static or time-variable gravity field. Their progress and development in the recent years has been induced by successful satellite missions, such as GOCE, GRACE and CHAMP and this will continue in the future missions. Resolution and agreement with quality terrestrial data...

Topographic and topoisostatic reductions of gravity field measurements are important in geodesy and geophysics. Reductions filter high frequencies from gravity which are then used in geoid modelling or investigations of the Earth's structure. Practical computations of reductions are performed using digital elevation/bathymetric models as input data...

A rise of a mean global sea level recorded during the 20th and 21st century is one of the most important indicators of climate change, which induces the thermal expansion of the oceans (steric effect) and ice melting. The mean rates of global sea level rise are estimated at around 3.1 mm a year. Those rates are routinely calculated from tide gauge...

The land cover changes of the area result from both nature-induced activities that are sometimes indirectly caused by human influence, and direct human-induced activities such as land use change, deforestation, city expansions, and other. Therefore, the land cover change can indicate climate changes of the geographic area as well as the change of t...

Changes in the height of the ocean can be described through the relative and absolute sea level changes depending on the geodetic reference the sea level records are related to. Satellite altimetry provides absolute sea level (ASL) measurements related to the global geodetic reference, whereas tide gauges provide relative sea level (RSL) measuremen...

The mean rate of global sea level rise is estimated to be ~3.1 mm yr−1. Those rates are routinely calculated from tide gauge measurements and satellite altimetry. However, regional rates that are driven by local geophysical processes can vary significantly. Thus, the impact of sea level change in the areas that adjoin the oceans should be evaluated...

This paper presents empirical research on coordinate transformation models that enable coordinate transformations between the historical astro-geodetic datums and datums related to the European Terrestrial Reference System (ETRS), through a case study of the Republic of Croatia. Thirteen models were investigated for the transformation from the hist...

Height (altitude) determination in geodesy is faced with problems that are directly attributed to the method of measurements and used geoid solutions. Due to the reliability of CROPOS as well as growing progress in geoid determination (increase of their external and internal accuracy), GNSS observations using CROPOS_VRS_HTRS96 VPPS service became m...

It is well-known that the Mediterranean Sea is challenging both in terms of geoid and Mean Dynamic Ocean Topography (MDOT) determination due to its geodynamic and oceanic features. Poor gravity data coverage and their outdated nature, along with the fact that the gravity and geoid slopes in the Mediterranean reach significant values with high varia...

This study presents a successful determination of a local millimeter geoid model and discuss over an imposed concerns related to the vertical datum based on such geoid model. The geoid model is computed over a small area of 600km2 in central Croatia, with the KTH method. The area is unique regarding its densely coverage with terrestrial gravity dat...

Data, models, publications, and software are fundamental part of research in physical geodesy and related scientific fields. They are continuously published and their finding, accessing and preparation for usage require investing significant efforts and time. This is due to: (1) different international and local, private and public data publishers,...

With nowadays high resolution Global Geopotential Models (GGMs), traditional geoid approximation with the Remove-Compute-Restore (RCR) procedure needs revisiting both in terms of the numerical and the methodological steps followed. This becomes evident if one considers the high degree of expansion of the latest combined GGMs, corresponding to frequ...

Comparison of combined solution of Croatian Positioning System (CROPOS) and positioning systems of neighboring countries (Slovenia - SIGNAL, Hungary - GNSSnet.hu and Montenegro - MontePOS), computed from 1741 daily solutions (ETRF2000, e2011.31) for the time span of ~ 5 years with the first adjustment of CROPOS network (GPSW 1506, ETRF2000 (R05), e...

Geomagnetic information, as found on topographic and navigational maps, comprises of the declination and its annual variation. Geomagnetic information (GI) is frequently obtained from (1) publicly available global geomagnetic models, e.g. IGRF-12, or (2) a model tailored at national or regional scales, e.g. GI2009.5 in Croatia. We will inquire two...

Since the establishment of CROPOS, almost seven years have passed. Initial and also the last adjustment CROPOS network was carried out in 2008 using only seven 24h session data in GPS Week 1503 (ETRF2000 R05; e2008,83). In the recent period there have been significant changes - Croatian State Geodetic Administration (CSGA) signed an agreement on th...

Modernization of height reference systems has started in the past decade in the field of basic surveying work in the world. It was triggered mostly by intensive development and daily use of satellite positioning methods, as well as by increased accuracy of global and regional gravity models. The accomplishment of one-centimetre accurate geoid model...

Dubrovnik, the Croatian and the world cultural monument of the highest category, that has been included in UNESCO's World Heritage List since 1979, is placed in seismic very active area. Throughout the history, the buildings in the city suffered a large amount of damage caused by natural disasters and by human action. The most critical of all these...

The Mediterranean Sea has always been a lab for geosciences, given its geodynamic peculiarities, the large short-scale variations of the gravity field and the complex circulation. Within the GEOMED 2 project, new improved representations of the Mediterranean marine geoid have been deemed as necessary, so that the Mean Dynamic sea surface Topography...

The unique features of the Mediterranean Sea, with its large gravity variations, complex circulation, and geodynamic peculiarities have always constituted this semi-enclosed sea area as a unique geodetic, geodynamics and ocean laboratory. The main scope of the GEOMED 2 project is the collection of all available gravity, topography/bathymetry and sa...

Conformal coordinate transformations very often are not accurate enough to be used for the coordinate transformations between local and global geodetic datums because of the inhomogeneity of the spatial data in different geodetic datums. Therefore, distortion modeling is used to improve the accuracy of the coordinate transformations. This paper pre...

Several coordinate transformation models enable performing of the coordinate transformations between the historical astro-geodetic datums, which were utilized before the GNSS (Global Navigation Satellite System) technologies were developed, and datums related to the International Terrestrial Reference System (ITRS), which today are most often used...

The article describes chronology of all basic geodetic works through main projects details and obtained results in period from recognition of Croatia as a sovereign and independent state by the international public to 2009 that is in period of 18 years. Article also describes inherited geodetic reference systems of Republic of Croatia (HDKS, AVD187...

Croatia has more than five hundred islands majority of which has the surface smaller than one km square, while the largest island exceeds even 400 km squares. ln accordance to the large differences of the islands' surfaces, 10 % of the islands are permanently inhabited while the rest of the islands record an increasing rate of the real estate trans...

The Mediterranean Sea has always been of economic and ecological importance to its surrounding countries. A better understanding of its currents is necessary for the management of fishery resources, potential pollution, and maritime security. Currents can be derived from the Mean Dynamic sea surface Topography (MDT), which can be estimated by subtr...