The
Institut für Erdmessung (IfE) was involved in high-resolution and
high-precision gravity field modelling since about 1970. Starting with the
local test network Westharz (Torge 1977), significant progress was made in
regional and global gravity field modelling within the framework of a
collaborative research center project (SFB 149, Geodetic and remote sensing
methods onshore and offshore) funded from 1975-1985 by the German Research
Foundation DFG (e.g., Torge et al. 1984). From this project, the gravimetric
quasigeoid EGG1 (European Gravimetric Geoid 1) for Europe and surrounding
marine areas (Torge et al. 1982) as well as the corresponding astrogravimetric
solution for Europe (Brennecke et al. 1983) evolved. The accuracies of these
models were at the dm level. The transition to accuracies at the cm level was
demonstrated successfully for the first time in a local test network near
Hannover using high-resolution point gravity and terrain data in combination
with a global geopotential model (Denker und Wenzel 1987). Corresponding
computations with the spectral combination technique and least-squares
collocation were then extended to Northern Germany (Denker 1988), the old West
German states (Denker 1989) and finally to entire Europe (e.g., quasigeoid
model EGG97, Denker und Torge 1998). Further details on the development and the
respective status of geoid modelling in Europe can be found in publications in
the German "Zeitschrift für Vermessungswesen" by Torge et al. (1983),
Torge and Denker (1991), Denker (1996) as well as Torge and Denker (1999).
Furthermore, the gravity field modelling studies at the Institut für
Erdmessung (IfE) lead to the habilitation thesis from Wenzel (1985) and the
dissertations from Weber (1984), Bäumker (1984), Denker (1988), Bašic
(1989), Grote (1996), Behrend (1999) and Roland (2005).
The European
geoid and quasigeoid computations were carried out at IfE from 1990 to 2003 as
the computing center of the IAG (International Association of Geodesy) geoid
sub-commission for Europe. Since 2003, the efforts are continued within an IAG
commision project, and a complete update is planned until 2007 (e.g., see
Denker et al. 2005). The "European Gravity and Geoid Project (EGGP)" proved
that significant accuracy improvements are possible in central Europe through
the use of updated gravity field data sets and GRACE geopotential models
(Denker, 2006). Moreover, the gravity field data sets from the European Geoid
Project are also utilized in connection with the validation and calibration of
the satellite gravity field missions CHAMP, GRACE und GOCE (e.g., see Denker
2003, Roland 2005).
Besides the gravimetric geoid and quasigeoid
computations, also combined solutions were developed utilizing GPS and
levelling data (Denker 1998, Denker et al. 2000). A particular example is the
combined quasigeoid model for Germany (German Combined (Quasi)Geoid 2005,
GCG2005; Liebsch et al. 2006) which resulted from two independent computation
methods applied within a cooperation project of the "Bundesamt für
Kartographie und Geodäsie" (BKG) in Frankfurt/Main and the "Institut
für Erdmessung" (IfE). Furthermore, a number of local and regional gravity
field models (especially geoid) were developed in cooperation with scientific
and commercial institutions, e.g., computations for Poland, Hungary, the former
GUS states, selected countries in South America and Arabia, as well as a
cooperation with Japanese colleagues (Kuroishi und Denker 2001).
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- Bašic, T.:
Untersuchungen zur regionalen Geoidbestimmung mit "dm"-Genauigkeit. Wiss. Arb.
der Fachr. Vermessungswesen der Univ. Hannover, Nr. 157, Hannover, 1989.
- Bäumker, M.: Zur
dreidimensionalen Ausgleichung von terrestrischen und Satellitenbeobachtungen.
Wiss. Arb. der Fachr. Vermessungswesen der Univ. Hannover, Nr. 130, Hannover,
1984.
- Behrend, D.:
Untersuchungen zur Schwerefeldbestimmung in den europäischen Randmeeren.
Wiss. Arb. der Fachr. Vermessungswesen der Univ. Hannover, Nr. 229, Hannover,
1999.
- Brennecke, J., D.
Lelgemann, W. Torge, H.-G. Wenzel: A European astro-gravimetric geoid.
Deutsche Geod. Komm., Reihe B, Nr. 269, Frankfurt a.M., 1983.
- Denker, H.:
Hochauflösende regionale Schwerefeldbestimmung mit gravimetrischen und
topographischen Daten. Wiss. Arb. der Fachr. Vermessungswesen der Univ.
Hannover, Nr. 156, Hannover, 1988.
- Denker, H.: A new
gravimetric quasigeoid for the Federal Republic of Germany. Deutsche Geod.
Komm., Reihe B, Nr. 291, München, 1989. Denker, H.: Stand und Aussichten
der Geoidmodellierung in Europa. Z.f.Verm.wesen 121, 264-277, 1996.
- Denker, H.: Evaluation
and Improvement of the EGG97 Quasigeoid Model for Europe by GPS and Leveling
Data. Proceed. Second Continental Workshop on the Geoid in Europe, Budapest,
Hungary, March 10-14, 1998, Reports of the Finnish Geodetic Institute 98:4,
53-61, Masala, 1998 (download
pdf-file).
- Denker, H.: Computation
of Gravity Gradients Over Europe for Calibration/Validation of GOCE Data. In:
I.N. Tziavos (Ed.): Gravity and Geoid 2002, 3rd Meeting of the International
Gravity and Geoid Commission, GG2002, Thessaloniki, Greece, Aug. 26-30, 2002,
287-292, Publishing Ziti, Thessaloniki, 2003 (download
pdf-file).
- Denker, H.: Das
Europäische Schwere- und Geoidprojekt (EGGP) der Internationalen
Assoziation für Geodäsie. Z.f.Verm.wesen 131, p. 335 - 344, 2006 (download
pdf-file).
- Denker, H., J.-P. Barriot,
R. Barzaghi, R. Forsberg, J. Ihde, A. Kenyeres, U. Marti, I.N. Tziavos:
Status of the European Gravity and Geoid Project EGGP. In: C. Jekeli, L.
Bastos, J. Fernandes (eds.): Gravity, Geoid and Space Missions - GGSM2004, IAG
Internat. Symp., Porto, Portugal, 2004. IAG Symp., Vol. 129, 125-130, Springer
Verlag, Berlin, Heidelberg, New York, 2005 (download pdf-file).
- Denker, H., W. Torge:
The European Gravimetric Quasigeoid EGG97 - An IAG supported continental
enterprise. In: R. Forsberg, M. Feissel, R. Dietrich (eds.): Geodesy on the
Move - Gravity, Geoid, Geodynamics and Antarctica. IAG Symp., Vol. 119,
249-254, Springer Verlag, Berlin, Heidelberg, New York, 1998 (download pdf-file).
- Denker, H., W. Torge, G.
Wenzel, J. Ihde, U. Schirmer: Investigation of Different Methods for the
Combination of Gravity and GPS/Levelling Data. In: K.P. Schwarz (Ed.): Geodesy
Beyond 2000 - The Challenges of the First Decade. IAG Symposia, Vol. 121,
137-142, Springer Verlag, Berlin, Heidelberg, 2000(download pdf-file) .
- Denker, H., H.-G.
Wenzel: Local geoid determination and comparison with GPS results. Bulletin
Géodésique 61, 349-366, 1987.
- Grote, T.: Regionale
Quasigeoidmodellierung aus heterogenen Daten mit "cm"-Genauigkeit. Wiss. Arb.
der Fachr. Vermessungswesen der Univ. Hannover, Nr. 212, Hannover, 1996 .
- Kuroishi, Y., H.
Denker: Development of Improved Gravity Field Models Around Japan. In: M.G.
Sideris (ed.): Gravity, Geoid and Geodynamics 2000, GGG2000 IAG Internat.
Symp., Banff, Alberta, Canada, July 31 - August 4, 2000. IAG Symp. Vol. 123,
317-322, Springer-Verlag, Berlin Heidelberg New York, 2001.
- Liebsch G., U. Schirmer, J.
Ihde, H. Denker, J. Müller.: Quasigeoidbestimmung für
Deutschland. DVW-Schriftenreihe, No. 49, 127-146, 2006.
- Roland, M.:
Untersuchungen zur Kombination terrestrischer Schweredaten und aktueller
globaler Schwerefeldmodelle. Wiss. Arb. der Fachr. Vermessungswesen der Univ.
Hannover, Nr. 254, Hannover, 2005.
- Torge, W.:
Untersuchungen zur Höhen- und Geoidbestimmung im dreidimensionalen
Testnetz Westharz. Z.f.Verm.wesen 102, 173-186, 1977. Torge, W., H. Denker: Zur
Entwicklung der Geoidmodellierung in Europa. Z.f.Verm.wesen 116, 220-230, 1991.
- Torge, W., H. Denker:
Zur Verwendung des Europäischen Gravimetrischen Quasigeoids EGG97 in
Deutschland. Z.f.Verm.wesen 124, 154-166, 1999.
- Torge, W., F.M. Monka, G.
Weber, H.-G. Wenzel: Bericht über die Tätigkeiten des
Teilprojekts P1 "Geoidbestimmung im Küsten- und Meeresbereich" im Jahre
1983. SFB 149, Jahresbericht 1983, Wiss. Arb. der Fachr. Vermessungswesen der
Univ. Hannover, Nr. 136, 9-20, Hannover, 1984.
- Torge, W., G. Weber, H.-G.
Wenzel: Computation of a high resolution European Gravimetric Geoid.
Proceed. 2nd Internat. Symp. on the Geoid and Mediterranean Area, 437-460, Rom,
1982.
- Torge, W., G. Weber, H.-G.
Wenzel: Ein hochauflösendes gravimetrisches Geoid für Europa und
angrenzende Meeresbereiche. Z.f.Verm.wesen 108, 321-331, 1983.
- Weber, G.:
Hochauflösende mittlere Freiluftanomalien und gravimetrische
Lotabweichungen für Europa. Wiss. Arb. der Fachr. Vermessungswesen der
Univ. Hannover, Nr. 135, Hannover, 1984.
- Wenzel, H.-G.:
Hochauflösende Kugelfunktionsmodelle für das Gravitationspotential
der Erde. Wiss. Arb. der Fachr. Vermessungswesen der Univ. Hannover, Nr. 137,
Hannover, 1985.
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