July 13, 2016

Transcription

July 13, 2016

The GOCESeaComb and GOCE+++ PRODEX Projects Objectives and Results
Aristotle University of Thessaloniki
Department of Geodesy and Surveying ‐ GravLab
Ilias N. Tziavos
PRODEX Project Coordinator
tziavos@topo.auth.gr
Presented at the
PRODEX DAY – ATHENS
Athens, Greece
July 13, 2016
GOCESeaComb & GOCE+++
PRODEX DAY – ATHENS – July 13, 2016
The GOCESeaComb and GOCE+++ PRODEX projects http://olimpia.topo.auth.gr/GOCESeaComb/
July 1, 2012 ‐ June 30, 2014
http://olimpia.topo.auth.gr/GOCE_HSU_DOT_g/
March 1, 2016 ‐ July 30, 2017
OUTLINE
The GOCESeaComb and GOCE+++ projects
o Objectives
o Expected results o The team
Results from the GOCESeaComb and GOCE+++ projects
o GOCESeaComb final results and connection to other sciences and engineering projects
o GOCE+++ early results and outlook
GOCESeaComb
“External calibration/validation of ESA’s GOCE mission and contribution to
dynamic ocean topography and sea level change determination through
stochastic combination with heterogeneous data – GOCE-SeaComb”
GOCESeaComb was focusing on exploiting ESA’s GOCE mission data, along with satellite altimetry and in‐situ observations:
1. To determine the Geoid, Mean Sea Level (MSL) and Dynamic Ocean Topography (DOT). 2. To develop the methodologies to be utilized for the validation of GOCE data and perform their validation against other GGMs (EGM2008) and local gravity data.
3. To develop and apply the methodologies for the optimal combination of GOCE data with altimetric and terrestrial gravity data for geoid, MSL and DOT determination in the Mediterranean Sea.
GOCESeaComb
GOCESeaComb was funded by the European Space Agency (ESA) within its Scientific Experiment Development Program (PRODEX) in response to the 1st PRODEX Programme Call for Greece.
The duration of the project was 24 months between July 1, 2012 and June 30, 2014. The project team was composed by:
o Prof. Dr. Ilias N. Tziavos, Principal Investigator
o Dr. George S. Vergos, Co‐Investigator
o Dr. Vassilios N. Grigoriadis, senior researcher
o Dr. Eleni A. Tzanou, senior researcher
o Dipl. Eng., MSc, Dimitrios A. Natsiopoulos, junior researcher
GOCESeaComb – http://olimpia.topo.auth.gr/GOCESeaComb/
GOCESeaComb – http://olimpia.topo.auth.gr/GOCESeaComb/
GOCESeaComb ‐ http://olimpia.topo.auth.gr/GOCESeaComb/
GOCESeaComb ‐ http://olimpia.topo.auth.gr/GOCESeaComb/
GOCE+++ (HSU, DOT, g)
“Height System Unification, Dynamic Ocean Topography and gravity field
determination with GOCE Global Geopotential Models employing stochastic
methods and heterogeneous data sources – GOCE+++”
GOCE+++ exploits the results and findings of GOCESeaComb and its focus targets the utilization of GOCE SGG and GGM data in order to:
෡௢ ) for Greece based 1. Determine an optimal unified zero‐level geopotential value (ܹ
on GOCE GGMs and unify the LVDs of the Greek islands to the mainland vertical reference datum.
2. Estimate the mean DOT for the Mediterranean basin based on GOCE GGMs and altimetry‐derived MSS using filtering in both the space and frequency domain.
3. Determine an improved geoid model for the wider Hellenic territory using GOCE SGG data and local free‐air gravity anomalies.
GOCE+++ (HSU, DOT, g)
GOCE+++ is funded by ESA within its Scientific Experiment
Development Program (PRODEX). GOCE+++ is a continuation of
the successfully completed GOCESeaComb Project.
The duration of the project is 18 months between March 1, 2016 and July 30, 2017. The project team was composed by:
o Prof. Dr. Ilias N. Tziavos, Principal Investigator
o Dr. George S. Vergos, Co‐Investigator
o Dr. Vassilios N. Grigoriadis, senior researcher
o Dr. Eleni A. Tzanou, senior researcher
o Dipl. Eng., MSc, Dimitrios A. Natsiopoulos, junior researcher
GOCE+++ ‐ http://olimpia.topo.auth.gr_GOCE_HSU_DOT_g/
GOCE data processing – Geo‐database generation  GOCE gravity gradiometry data (raw and processed data)
 Satellite altimetry data (GEOSAT, ERS1/2, GEOSAT, T/P, ENVISAT,
Jason 1/2, GEOSAT-FO, Cryosat2, SARAL/Altika)
 Surface gravity data
 Terrain and bathymetry data (DTMs/DBMs)
 GPS/leveling at benchmarks
 Geoid heights, DOT heights, gravity anomalies and other components
of the gravity field
Why focus on GOCE
o First ever measurements of gravity from space based on gradiometric
observations (Satellite Gravity Gradiometry – SGG)
o GOCE mapped with unprecedented detail the Earth's gravity field flying at a very low altitude of ~250 km o GOCE’s primary instrumentation was a gravity gradiometer consisting of Mission Duration: 4/2009 – 10/2013
three pairs of accelerometers GOCE, a Ferrari on Space to measure measuring gravitational gradients Earth’s gravity field along three orthogonal axes.
(Images courtesy ESA)
Why focus on GOCE
The goals of GOCE were:
o To determine gravity‐field anomalies with an accuracy of 10−5 ms−2 (1 mGal)
o To determine the geoid with an accuracy of 1–2 cm
o To achieve the above at a spatial resolution better than 100 km
Mission Duration: 4/2009 – 10/2013
GOCE, a Ferrari on Space to measure Earth’s gravity field (Images courtesy ESA)
Why focus on GOCE
 Txx

Wc   Tyx
T
 zx
Txy
Tyy
Tzy
Txz 

Tyz 
Tzz 
GOCE Global Geopotential Models – Satellite and Combined models
T r   W r   U r 
GM
T r  
R

a
 

n2  r 
Cnm
Snm
Pnm cos  
n n
 C
m 0
nm
cos m  S nm sin m Pnm cos  
Fully normalized potential coefficients
Associated Legendre functions
GOCESeaComb results
Availability of many GOCE/GRACE GGMs based on different methodologies and number of GOCE data used o TIM (time‐wise)
o SPW (space‐wise)
o DIR (direct)
o GOCO (combined GOCE/GRACE)
o EIGEN (combined with Gravity and Altimetry)
o Release 1 (R1 – 2 months GOCE observations)
o Release 4 (R4 – 26.5 months GOCE observations)
o Release 5 (R5 – 26.5 months GOCE observations entire mission)
Validation of their contribution over Greece GOCESeaComb & GOCE+++
Methodology
Spectral evaluation
o GGM spectra and error spectra
*
 C nm
, Snm ,   C ,  S
*
nm
nm
o Signal to Noise Ratio and GAIN (w.r.t. EGM2008) for each GGM
o Geoid degree and error degree variances
o GGM difference degree variance relative to EGM2008
Methodology
Validation with GPS/Leveling geoid heights over Greece
o GGM differences to their nmax
N  N GPS / Lev  Nni max  No
i
NGGM
, i  DIR / TIM / SPW / GOCO / EIGEN  R1, R 2, R 3, R 4
Spectral Evaluation
DIR‐R1 error spectrum GOCESeaComb & GOCE+++
Spectral Evaluation
Spectral Evaluation
Spectral Evaluation
Spectral Evaluation
Spectral Evaluation
DIR‐R5 signal/error compared to EGM08 signal/error
EGM08 and GOCE (Tzz) residual geoid models
GOCE data after filtering
Evaluation with GPS/Leveling data
Validation with GPS/Leveling geoid heights over Greece
o 1542 collocated GPS/Leveling BMs
o Unified Height Reference System and Tide System o All computations in GRS80
o No relative to the IAG Wo of 62636856.0 m2/s2
Evaluation with GPS/Leveling data
GPS/Leveling BMs for the validation
provided by
Hellenic Cadastre SA
Validation with GPS
Improvement of GOCE Global Geopotential Models against EGM08
1 ‐ 2 cm
Validation with GPS
TIM‐R5
EGM08 DIR‐R5
TIM‐R5, DIR‐R5 and EGM08 geoid height differences at the levelling BMs Improvement with GOCE‐
based models 1 ‐ 2 cm
DOT model development
Comparisons with models based on in‐situ oceanographic data (Rio et al. 2007) resolution: 3.5 arcmin
sd: ± 2 ‐ 4 cm
The MDOT of the GOCESeaComb Project (Altimetric model – Gravimetric model)
Gravimetric model (GOCE + EGM08 + surface gravity data)
Circulation modeling
Comparisons with models based on in‐situ oceanographic data (Rio et al. 2007) resolution: 3.5 arcmin
sd: ± 6 ‐ 7 m/s
The circulation model of the GOCESeaComb project GOCESeaComb & GOCE+++
GOCE+++ early results on Height System Unification
GPS/Leveling BMs  Wo determination  Height System Unification
The Greek Local Vertical Datum is not unified, while the islands usually realize their own vertical reference system
Wj
Wi
Wk
Wi
Wi  Hihelmgihelm
W j
 Wk
W  WôLVD
Least‐Squares Collocation adjustment schemes GOCESeaComb & GOCE+++
Connection of the island Local Vertical Datum
to the mainland Greek Vertical Reference System for Height System Unification (using enhanced DIR‐R5)
Combined GOCE/GRACE GGMs for mainland
o DIR‐R4 (140)+EGM08 WÔLVD  62636860.92  0.008m2 / s2
o TIM‐R4 (140)+EGM08 WÔLVD  62636860.96  0.008m2 / s2
o DIR‐R5 (140)+EGM08 WÔLVD  62636860.95  0.008m2 / s2
o TIM‐R5 (150)+EGM08 WÔLVD  62636860.93  0.008m2 / s2
LVD
Great consistency for the GOCE GGMs in Ŵo
 WÔLVD  0.3  0.4 cm
GOCESeaComb & GOCE+++ benefits
 A comprehensive geo‐database has been created including:
(a) Satellite altimetry data, (b) GOCE gradient data, (c) surface gravity
data, (d) bathymetry data, (e) GPS/leveling data
 The products of both projects are needed by other branches of
geosciences and are of importance for engineering projects
 Oceanography needs accurate determination of the geoid in support
of MSL and DOT determination
 Spatial scales up to 80‐100 km targeted by the projects resolve
mesoscale processes, eddies and large scale circulation
 In geodynamics a high‐resolution geoid based on GOCE combination
with in‐situ gravity data, as done in the GOCESeaComb and GOCE+++
projects, can reveal sedimentation and fracture zoning
GOCESeaComb & GOCE+++ benefits
 A high accuracy geoid serves as a reference surface for deformation
and tectonic plate movement monitoring
 Engineering applications are benefited the most, since HSU allow the
derivation of absolute and relative heights in a common frame, with
homogeneous accuracy and without the necessity to transform
between various local systems/frames
 Exploration geophysics for natural resources screening can be
benefited from a combined GOCE, for long to medium wavelengths,
and in‐situ data, for small wavelengths, processing
 Countries like Greece with many different local VRS can now use a
unified reference geopotential value as the origin of its network
Results dissemination
 Results published in IAG Proceedings Journal and Advances in Space Research
 Results presented at IAG, IUGG, EGU and IGFS conferences
Details for the complete list of publications/presentations at the websites
http://olimpia.topo.auth.gr/GOCESeaComb/
The GOCESeaComb and GOCE+++ PRODEX Projects http://olimpia.topo.auth.gr/GOCESeaComp/

July 13, 2016

Transcription

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