Gravity Field and Steady-State Ocean Circulation Explorer (GOCE)
description
Transcript of Gravity Field and Steady-State Ocean Circulation Explorer (GOCE)
S 1The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
Gravity Field and Steady-State Ocean Circulation
Explorer(GOCE)
Graphics files in directories:
d:\nico\proj\GOCE\graphics\*
d:\nico\proj\GOCE\GranadaIIreport\graphics
d:\images\geo
Graphics files in directories:
d:\nico\proj\GOCE\graphics\*
d:\nico\proj\GOCE\GranadaIIreport\graphics
d:\images\geo
S 2The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Issues of Concern
Earthquakes &volcanic activities
Thermohalineocean circulation & heat transport
Ice Sheet Melting
Global unificationof height system
Sea level change
S 3The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE International Programme
• International Lithosphere Programme (ILP)
• Int. Decade of Natural Disaster Reduction (IDNDR)
• International Association of Geodesy (IAG)
• World Climate Research Programme (WCRP)- GEWEX- WOCE/CLIVAR- GCOS/GOOS- ACSYS/CLIC
• International Geosphere/Biosphere Program (IGBP)- LOICZ
• Intergovernmental Oceanographic Commission (IOC)- GLOSS
Earthquakes andVolcanic Activities
Global Unification ofHeight System
Thermohaline Ocean Circulation and Transportof Heat.
Ice Sheet Melting
Sea Level Change
S 4The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Research Goals
• Solid Earth Physicsanomalous density structure of lithosphere and upper mantle
• Oceanographydetermination of dynamic ocean topography
• Ice Sheetsimproved knowledge of ice sheet balance
• Geodesyunified height systems, “levelling by GPS”
and from the above improved Sea Level Change Studies
S 5The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
• determine the Earth’s gravity field with an accuracy of
1 mgal (1 mgal = 10-5 m/s2 )
• determine the geoid (= equipotential surface for a hypothetical ocean at rest) with an accuracy of 1 cm
• achieve this at length scales down to L = 100 km
(degree and order 200)
Mission Objectives
S 6The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Presentation Outline
• Mission Rationale
• Science & Application
• Mission Design
• Performance
• Conclusions
S 7The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
• terrestrial gravity anomalieslarge unsurveyed areas, heterogeneous data, offsets and biases
• geoid mapping via satellite altimetry not acceptable for oceanography
• satellite orbit analysis- only large spatial scales are satisfactory - heterogeneous data - error correlation
Mission Rationale
Limitations of Existing Gravity Field Data
S 8The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
Incomplete Data Coverage
gravdensBGI.gifgravdensBGI.gif
S 9The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
GEOID
terrainALTIMETRY
Mission Rationale
Limitation with Satellite Altimetry
geoid_altim2.pptgeoid_altim2.ppt
S 10The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE egm.bw.epsegm.bw.eps
Mission Rationale
Signal Accuracy versus Spatial Scales
S 11The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
• Satellite-to-Satellite Tracking in High-Low Mode
SST-hl
• Satellite-to-Satellite Tracking in Low-Low Mode
SST-ll
• Satellite Gravity Gradiometry
SGG
Mission Rationale
Spaceborne Gravity Field Methods
S 12The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
GPS - satellites
Earthmassanomaly
3-D accelerometer
Mission Rationale
SST - hl
sst_hl.epssst_hl.eps
SST - hl
S 13The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
SST - hl
GPS - satellites
Earthmassanomaly
Mission Rationale
Combined SST - ll and SST - hl
sst_ll.epssst_ll.eps
SST - ll
S 14The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
SGG
Earthmassanomaly
GPS - satellites
Mission Rationale
Combined SGG and SST - hl
gradiometry.epsgradiometry.eps
SST - hl
S 15The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
• Orbit as low as possible and near polar
• Uninterrupted tracking in 3-D
• Isolation of gravitational signal
• Amplification of gravitational signal by principle of differentiation
Mission Rationale
Gravity Field Satellite Design Criteria
S 16The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
• Orbit altitude 250 km and sun-synchronous (inc.= 96.5˚)
• Uninterrupted and 3-D high-low tracking with GPS satellites relative to ground network
• Drag-free system and elimination of residual drag common mode rejection
• Gravity signal amplification by gradiometry (differential accelerometry)
in addition: all component gradiometer
Mission Rationale
GOCE versus Design Criteria
S 17The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
Full Tensor Gradiometer Measurements
goce_eqn.jpggoce_eqn.jpg
gravity gradient
angular acceleration
angular velocities
acceleration differentiation
S 18The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE
translationalforces
angularforces
starsensors
drag control angular control
*
*GPS/GLONASS
SST -hl
GRAVITY GRADIOMETER
measures:
GRAVITY GRADIENTS
angular accelerations
common mode accelerations
A B
Mission Rationale
Instrument Concept
satellit.pptsatellit.ppt
S 19The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
Uniqueness
CGG_fill_bw.eps
CGG_plainx.eps
CGG_overlayx.eps
CGG_fill_bw.eps
CGG_plainx.eps
CGG_overlayx.eps
SGG achieves highest attainable resolution SGG and SST-ll are complementary
S 20The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
The 3-D structure of the Gravity Field
vik.bw.epsvik.bw.eps
S 21The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
The 3 -D structure of the Error Coefficient
S 22The Four Candidate Earth Explorer Core Missions Consultative Workshop 12-14 October 1999, Granada, Spain, Revised 2006-01-05 by CCT
GOCE Mission Rationale
The Interdisciplinary Research
GIGGOS.doc (.eps)GIGGOS.doc (.eps)
Earth System Model
- ocean- ice sheet
- lithosphere- mantle
- core
Solid Earth Physics
Geodesy
Cryosphere Oceanography
Sea Level Change