Geodetic applications of GNSS in the Black Sea region

Transcription

1 BALGEOS II - Balkan countries integration into GGOS Second workshop, January, 2010 Vienna - AUSTRIA Geodetic applications of GNSS in the Black Sea region Lyubka Pashova CENTRAL LABORATORY OF GEODESY BULGARIAN ACADEMY OF SCIENCES 1

2 Presentation Outline Introduction GNSS applications in the Black Sea region Geodynamical studies Unification of Vertical Reference Systems Navigation, maping, coastal engineering etc. Unresolved problems Conclusions 2

3 Introduction Black Sea occurs within the Anatolian sector of the Alpine- Himalayan orogenic system the present-day tectonics of the Black Sea has been a puzzle, due to rates of available GPS/GNSS sites are poorly known Seismic activity is assumed as low-moderate The western end of the Black Sea, north of the Marmara Sea, Bulgaria, Romania and Ukraine should be influenced by extensional tectonics

4 Tectonic map of the Black Sea region

5 Recent crustal horizontal movements E. TARI et al.: 2000

6 Permanent GNSS sites in the Black Sea region ID number Period/epoch of observations Since MM YY 0 B L h v N [mm/yr] v E [mm/yr] v UP [mm/yr] v N [mm/yr] v E [mm/yr] v UP [mm/yr] 0 m ITRF2005,EPOCH ETRF2000(R05), EPOCH PERMANENT GPS SITES COST 02_ :09: :39: ± ± ± ± ± ± 0.33 EVPA 11_ :13: :09: ± ± ± ± ± ± 0.39 IGEO 07_ :01: :50: ± ± ± ± ± ± 0.56 ISTA 01_ :06: :01: ± ± ± ± ± ± 0.14 MIKL 11_ :58: :58: ± ± ± ± ± ± 0.28 TRAB 01_ :59: :46: ± ± ± ± ± ± 0.18 TUBI 08_ :47: :27: ± ± ± ± ± ± 0.15 ZECK 09_ :47: :33: ± ± ± ± ± ± 0.26 IGEO MIKL EVPA COST ZECK ISTA TUBI TRAB

7 GPS velocities with respect to Eurasia ETRF 2005 velocities of permanent GPS (in red) and Bulgarian sites (in black)

8 GPS velocities with respect to Eurasia The ETRF2005 vertical velocity for permanent GPS sites in the Black Sea region. The uplift is indicated in red, subsidence in blue ( Horizontal velocities of the Bulgarian GPS sites with respect to Eurasia

9 Vertical land movements from ALT-TG Garsia et al.: 2007

10 Unification of Vertical Reference Systems Integration of the Bulgarian levelling network in the UELN in 2003 (Sacher et al., 2004) Determination of the difference between EVRS and Baltic height systems Absolute and relative gravity measurements (Milev et al. 2003) Several GPS campaigns performed in the Black Sea region 1994, 1996, 1997, 1999, 2004, etc.

11 Bulgarian-Romanian GPS campaign The GPS campaign was performed in October BG001 control point of tide gauges in Burgas and 3 GPS points VAT1, BG002, VATG) in Varna Trimble 4000 SSI receiver with Geodetic L1/L2 ground plane antenna and two Trimble 5700 receivers with Geodetic Zephyr antennas The data were collected in ~ 48-hour session lengths (with except of point VATG) with 10 o -elevation cutoff and 15s sampling rate.

12 Control GPS point of the tige gauge Burgas Tide gauge in Burgas Location of GPS point in Burgas

13 Control GPS point of the tige gauge Varna Location of GPS point in Varna GPS point BG002

14 Geodetic gravity missions CHAMP (July 2000), GRACE (March 2002) and GOCE (2009) gravity missions geoid modeling and time variations of the geopotential, the ocean/atmosphere interactions, global and regional long-term and short-term sea level changes, etc. Worldwide unification of height systems Substantial contribution to study sea-level changes, ocean/atmosphere circulation, steric changes, changes in ocean volume, vertical land movements, ice mass changes, etc. Multi-disciplinary research and application in geophysics, oceanography and geodesy

15 Level Surfaces and Heights Systems Level Surfaces Earth s surface P υ W P Deflection of vertical Plumb line Mean Sea Level (MSL) Sea O j h = H o + N = H n + ζ Level Surface = Equipotential Surface (W) h P P O ζ H o(j) H n(j) N P Quasi-geoid Geoid W = W (j) O Reference Ellipsoid U = U O Geopotential Number (C P ) = W P W O H (Orthometric Height) = Distance along plumb line (P O to P)

16 Unification of the height systems Goal: to define a global height system (unified vertical datum) synthesizes all available data from space and in situ measurements, which can relate to a single level surface the geoid (W 0 ) - complex research problem Stages to achieve this goal: Establishing the relationships between the various vertical datums; Transform the national geodetic reference systems into regional (European) or global coordinate systems using GNSS; Continuously monitoring the reference zero points of different national height systems by GNSS

17 Height systems used in Bulgaria Black Sea system from 1930 to 1952 with zero point at TG in Varna, orthometric type of heights Baltic Sea system since 1952 with zero point at TG in Kronstadt (Baltic Sea), normal type of heights EVRS since 2003 with zero point at TG in Amsterdam, normal type of heights not officially accepted

18 Varna tide gauge zero point of Black Sea height system BG002

19 Kronstadt tide gauge - zero point of Baltic height system The Kronstadt Tide-Gauge a horizontal mark cut into the stone pier of a bridge over Kronstadt's Obvodny Canal showing the average water level of the Baltic in the period (established by the outstanding hydrographer Mikhail Reineke). Later a gauge for measuring seaievel was installed alongside, its zero reading corresponding to the mark.

20 Normaal Amsterdams Peil - zero point of EVRS The vertical datum is Normaal Amsterdams Peil (N.A.P.), fixed by an underground benchmark at Amsterdam. Originally the zero level of NAP was the average summer flood water level (not mean sea level) in the centre of Amsterdam, then still connected with the open sea, in Currently it is physically realized by a bench mark in brass in the centre of Amsterdam, which is a popular tourist attraction.

21 Unification of the height systems Zero Mean Estimations point Sea Level for of Black Earth at tide Sea geopotential gauge height in Varna value W system in used Black in Sea Bulgaria height till system 1952 with 0.00 m 0 at TG MSL = in in 68.17cm Baltic Varna ˆ Varna 2 2 Wo = ms Sea (epoch height 1930) system ~ m at TG in EVRS2007 Burgas 2 2 (Amsterdam) ˆ Burgas W = ~ ms m (~-0.04m) o Locations of islands in the Black Sea

22 Differences between altimetric and normal heights (a) - Differences between altimetric and quasi-geoid heights at the tide gauges before the adjustment;. (b) - Corrector surface. Due to inconsistency Shabla was not used in the corrector surface determination

23 EVRS and Bulgarian participation International GPS campaign (1997) to include co-located GPS points at tide gauges in EUVN95 network (195 points, 79 - EUREF, 53 - leveling benchmarks, 63 - tide gauge stations). Bulgaria participates with 3 GPS points SOFI, Varna (BG002) and Burgas (BG001). EUVN site distribution Scheme of control GPS points and bench marks in Varna and Burgas

24 EVRS (EVRF2007) The differences for the adjusted geopotential numbers for Bulgaria in EVRF2007 compared to EVRF2000 are within the range kgal*mm. According to Ihde et al. (2008) EVRS 2007 realization will be used as official vertical system everywhere in the EU countries. Inevitably coordinates (heights) will contain errors of any EVRF200x realization, which are taken as absolute (the transition from "old" national geodetic systems into ETRS1989 to be impeded after each new subsequent adjustment). Makinen (2004) recommends do not introduce EVRF2000 or EVRF200x as formal vertical system without taking into account geoid modeling with GOCE gravity mission the rapid update of the coordinates, taking into accounting the time factor. EVRF200x realizations approve the points heights.

25 GNSS unresolved problems in the Black Sea region The present geoid accuracy varies from one location to another. Chart Datum and different (improved) geoid models change over time, which creates a maintenance problem to the expected large volume of data. Local MSL changes over the time under the influence of global climate, global and local sea level rise, tectonic processes, etc. Different height system epochs lead to differences in calculating heights between the Black Sea neighboring countries due to initial "zero" points. In the region there is no overall height (vertical) system for hydrographic and navigation purposes. Practical difficulties for joint scientific researches, for navigation, engineering activities performed simultaneously by two or more countries in the Black Sea region.

26 Unresolved obstacles Practical tasks are performed in a local Black Sea system, while the height and depth on all topographic maps are in the Baltic height system. Problems related to the MSL of the Bulgarian tide gauge stations are subject to national debate in Coastal authorities and hygrograph service are need of local MSL. Problems with local subsidence's of the Varna and Burgas tide gauges. The heights/depths used in the Black Sea region should comply with international standards for the geodetic coordinate reference and vertical systems. The choice of optimal variant for practical use of GNNS and reconciliation of data for different heights/depths in the aquatic environment of the Black Sea is not only a scientific problem.

27 Conclusions All Black Sea countries will be integrated in the EVRS Project - needs to find out a local solution for the Black Sea region. Unification of different zero points of heights systems - elaborate a common local vertical reference frame for the region. Unified horizontal and vertical geodetic coordinate system a condition to elaborate the next generation three-dimensional Electronic Chart Display and Information System (ECDIS). Center for collecting and processing information.

28 Common vertical datum for the Black Sea region? The development of a seamless vertical datum would benefit for many applications: surveying and marine navigation, monitoring changes of the coastal areas, coastal resource management, erosion and accretion monitoring, flood monitoring and emergency response, maritime boundary delimitation, etc.

29 Thank you for your attention! 21