1. Consistent Ocean Mass Time Series from LEO Potential Field Missions
(CONTIM)
Team:
Jürgen Kusche + Roelof Rietbroek + Christina Lück, Bonn
Jens Schröter + Sergey Danilov + Alexey Androsov, Bremerhaven
Steffen Schön + Le Ren, Hannover
Current sea level rise ~3mm/a, how much of this is mass (Rietbroek et al., 2016, PNAS)?

2. Project CONTIM – Outlook to the 2nd phase of SPPWe
combine expertise on precise satellite orbit determination, gravity field/mass modeling, and physical oceanography
Retrieve, analyze and verify consistent time series of ocean mass variations from LEOs extending the GRACE time series.
Where are we now?
POD works well (equivalent or improved compared to others)
TVG comparable to other Swarm solutions  compare to OBP modeling  start work on inversion (with altimetry) for ocean mass and steric contribution
Observation weighting  separation of ionospheric effects/fluctuations (SPP) and  elimination of high frequency noise in orbit)
Modelling: small scale variations (eddies) do not average out over the GRACE/Swarm scale?
Relevant developments
GRACE lifetime + gap, GRACE-FO launch
Improvements in thermosphere modeling through SPP
GNSS Doppler Observations for test purposes available

3. Project CONTIM – Outlook to the 2nd phase of SPP
IfE: Kinematic Orbits
Jan-2016 (500km Gauss)
IGG solution computed with IfE orbits
IGG: TVG and mass change
ITSG-Grace2016
Time series of EWH (500km Gauss)
Orbits from ESA
IGG Swarm
ITSG-Swarm2016
Carrier phase + kinematic orbits of Swarm severely degraded under influence of ionospheric scintillation, could also degrade TVG
Will investigate impact of ionospheric scintillation on GPS phase observations and eliminate impact on orbit by adequate observation weighting
AWI: OBP Modeling with data assimilation
Next: Fingerprint Inversion
Use all results (NEQs) in a fingerprint inversion to split ocean mass changes into individual components

4. Project CONTIM – Outlook to the 2nd phase of SPP
Address in the second phase
Jointly
extend ocean mass time series further in the past using SLR (and possibly DORIS)
Swarm for linking GRACE and GRACE-FO
Bonn
use kinematic baselines ( IfE) as observations, Swarm drag modelling
Parameterization  Kalman filter to make trend of SHCs /ocean mass time-variable AND resolve fast ocean signals
Hannover
use Doppler frequency shift to improve the orbits  independent velocity obs?
investigate the impact of ionospheric scintillation on GPS observations and orbits
Bremerhaven
effect of small scale eddies, refining ocean models
apply data assimilation to (1) locate eddies correctly, (2) incorporate GRACE/Swarm results for analysis of deep ocean circulation and warming