Case study on heterogeneous geoid/ quasigeoid based on space borne and terrestrial data combination with special consideration of GOCE mission data impact

Proj. ID 10519 Dr. Kirco Arsov, Prof. Wen Hanjiang

and rest of the Dragon 3 team

Objectives• Assesment of GOCE mission with respect to ground gravity data in China and Finland; GOCE mission validation•Computation od one geoid solution for part of China and Finland with inclusion of GOCE and ground - based data in one model•Inclusion of GOCE models in the upcoming Nordic Geoid computation•Performance test of the HY-2 altimetry mission; gravity anomalies from altimeter data computation•Optimal filtering and combination of long wavelength satellite based models, special accent on GOCE mission•Asessment of different geoid solutions based on combination of different satellite models ; insight on GOCE performance

Project partners and roles• Dr. Kirco Arsov (FGI): Geoid techniques, data, numerics, data

reductions, GOCE modelling, Assessment of techniques• Prof. Wen Hanjiang (CASM) marine and terrestrial geoid,

altimetry processing, spectral methods, data acquisition coordination, computation techniques

• MSc. Hannu Ruotsalainen (FGI) gravity data acquisition, field campaigns, data smoothing, DEM, Seismic data, Density data

• MSc. Mirjam-Biker Koivula (FGI) : Geoid modelling, Spectral methods, GOCE models computation, Geoid assessment, Spectral geoid calculations: PhD thesis as outcome

Project partners and roles (cnt)

•Dr. Yanhui Cai (CASM): GPS processing and acquisition, GPS/Leveling preparation and screening, software coding•MSc Huanling Liu (CASM): Ph.D earth’s gravity field model derivation from GOCE observations, altimeter data processing•Yantian Xu(CASM): Ph.D, geoid determination and software coding•Wei Li (CASM) : Ph.D, GPS processing , software coding

Project partners and roles (cnt)

•CASM: Chinese data acquisition, chinese data preparation, screening, smoothing, Chinese geoid computation and assessment of satellite models with respect to ground data, processing and assessment of altimetry data and determination of gravity anomalies on sea, screening of chinese land gravity data, assessment of GOCE models, GOCE models inclusion in the final geoid solution, comparing with nordic solution, publishing results

Project partners and roles (cnt)•FGI: Update of the FGI gravity database, measurements screening and preparation, measurements reduction, GOCE models extraction , reduction and computation, GOCE models enhancements and filtering of local grav. Data, GOCE assessment with Finnish data (and possibly nordic), filtering of terrestrial measurements, study on combination of different long wavelength models with GOCE models, Finnish (and nordic) geoid computation by usage of stand alone and combined GOCE models, numerical investigations, justification of results with Chinese data and publication of results

FGI (and nordic) gravity database

FGI gravity database

FGI gravity database: vertical deflections

• Gravity measurements 590,000（ 500,000 on land ， 90,000 in ocean ）

• The accuracy of 5 ×5 mean free-air ′ ′gravity anomalies is ±9mGal

• Number of GPS/Leveling points ：1000

• Order-I leveling network : 93,360km

• Order-II leveling network : 136,369km

Chinese data description

Distribution of GPS/Leveling points

study area for geoid determination in China:

Longitude: 118°00′ ～ 123°00 ′Latitude: 27°00′ ～ 31°10 ′The topography changes from 2.5m to 1800

Data collection:Gravity dataMarine gravity anomalies derived from altimeter dataGPS/Leveling measurements

The topography of the study area

Chinese data description (cnt)

Data collection in China• collection of altimeter data(including HY-2

altimeter data), GPS/Leveling data, gravity measurements, DEM,marine gravity measurements near Zhejiang province,

ESA GOCE data• ESA gravity field models to be used• ESA GOCE PSO_2 data for orbit determination

tests and gravity extraction from orbits• Error var/cov of GOCE models• GRACE models• Altimetry: altimeter data from Jason-2,

Envisat,and HY-2,marine gravity measurements• GOCE gradiometry measurements :GOCE EGG

Level 1b/L2 (excluded EGM_GVC_2

Project schedule and expected results• 06/2012-06/2013 terrestrial data screening, collection,

filtering, reduction, study on methodology and software preparation, use of seismic and geological data for reductions.

• 06/2013-12/2013 Marine gravity anomalies from altimeter data, marine geoid determination, validation of earth's gravity field models from GOCE

• 01/2014-06/2015 Methods study for the derivation of the earth's gravity field model from GOCE gravity gradient data, validation of earth's gravity field models from GOCE, geoid determination in Zhejing province of China and Finland

Project schedule and expected results

• 01/2015-12/2015 Study and reporting on the analysis of the influences of long-wavelength earth's gravity field to the accuracy of geoid in Zhejiang province of China and in Finland.

• Jan. 2015-Dec.2015 cross-validation of HY-2 altimeter data, optimal combination of different altimiter missions for marine gravity anomalies and marine geoid.

• 01/2014-12/2014 Study and reporting on the analysis of the influences of long-wavelength earth's gravity field to the accuracy of marine gravity anomalies in China sea by comparing to the marine gravity measurements.

• 01/2015-12/2015 optimal combination of geoid improvements by using GOCE,altimeter,gravity measurements,DEM, GPS/Leveling

Project schedule and expected results

Young scientists training

• Mirjam Biker-Koivula will work toward her PhD dealing with geoid modelling. She will be actively involved into Finnish data preparation, screening and GOCE model inclusion. This project will be part of her PhD study

• Three Ph.D students from China are going to be involved in this project: Ms. Liu will focus on the marine gravity anomalies derivation and marine geoid determination by using heterogeneous observations, and the study of long-wavelength earth's gravity field contribution to geoid accuracy

Young scientists training (cnt)• Ms. Li will focus on the validation of earth's gravity

field models from GOCE by using the GPS/Leveling data in Chinese territory and the validation of marine gravity anomalies derived from altimeter data

• Mr. Xu will focus on cross-validation of HY-2 altimeter data by comparing to altimeter data from other missions, such as Jason-2, Envisat, etc. He will also study the gravity filtering techniques and optimal methods of data fusion

Young scientists training (cnt)• As outcome of this project we expect that our young

colleagues will present their results obtained in the course of this project in scientific meetings and conferences and that this will contribute to a great extent into their scientific career goals.

• 4 PhD theses are also furthermore expected as outcome of this project

Expected Project results• Assessment of GOCE products with terrestrial data from China

and Finland, maps of discrepancies, GOCE models accuracy tests, documentation of filtering/spectral enhancement methods and their usability

• Geoid solution for Finnland and part of China by inclusion of GOCE models

• Assessment of HY-2 Chinese altimeter mission.• 4+ Peer reviewed publications dealing with abovementioned

results.• 5 PhD theses of students involved in the project• Attending scientific conferences and assemblies and presenting

the project results

Thank you for your attention