The GOOS Space-Based Data Requirements

Space-Based Data Requirements for GOOS

The observing requirement specified for GOOS are based on in situ and satellite data. For satellite data GOOS will use both geostationary and polar orbiting satellites to achieve the necessary spatial resolution and to reduce the geophysical noise in climate signals. In situ data are necessary to provide calibration for the satellite sensors, to provide subsurface data, and to provide data where satellite coverage is poor. This page describes the applications, variables, and resolutions that have been specified for the space-based data.

The table below shows the space-based data requirements for GOOS. These initial requirements have been compiled with particular reference to the needs of the Global Ocean Data Assimilation Experiment (GODAE). GODAE is a major numerical modelling experiment that will assimilate ocean data from in situ observations and satellites. GODAE is likely, in general, to be more demanding in terms of spatial and temporal resolution, but with decreased emphasis on the deep ocean and perhaps slightly weaker accuracy requirements.

Global Observations of Ocean Circulation - Space-Based Data Requirements

Details Optimized requirements Threshold requirements
CodeApplicationVariableHorizontal Resolution (km)CycleTimeAccuracyHorizontal Resolution (km)CycleTimeAccuracy
Altimetry
A
Mesoscale variability
sea surface topography 25
7 d
2 cm
2 d
100
30 d
15 d
10 cm
B
Large scale variability
sea surface topography 100
10 d
2 cm
2 d
300
10 d
10 d
2 cm
C
Mean SL variations
sea surface topography 200
> 10 yr
1 mm/yr
10 d
1000
> 10 yr
10 d
5 mm/yr
D
Circulation, heat transport
sea surface topography 100
NA
1 cm
NA
500
NA
NA
5-10 cm
Remote Salinity
E
Circulation water transport
surface salinity 200
10 d
0.1 PSU
10 d
500
10 d
10 d
1 PSU
Scatterometry
F
Wind-forced Circulation
surface wind field 25
1 d
1-2 m/s 20E
1 d
100
7 d
7 d
2 m/s 30E
Sea Surface Temperature
G
NWP; climate, mesoscale models
Sea surface temperature 10
6 h
0.1EK (relative)
6 h
300
30 d
30 d
1EK
Sea Ice
H
Ocean-ice coupling warning
sea ice extent, concentration 10
1 d
2%
3 h
100
1 d
10 d
10%
Ocean Color
I
Biogeochemistry, transparency
ocean color signal 25
1 d
2%
1 d
100
1 d
1 d
10%
  Footnotes:

A requires wave height + wind (EM bias correction) measured from altimeter, water vapor content measured from on board radiometer, and ionospheric content / measured from 2 frequency altimeter.
B requires precise positioning system with an accuracy of 1-2 cm for a spatial resolution of 100 km.
C requires precise monitoring of transit time in the radar altimeter.
A, B and C require repeat track at + 1 km to filter out unknowns on geoid.
A requires adequate sampling which implies at least 2, and preferably 3, satellites simultaneously.
A, B and C require long lifetime, continuity, cross calibration.
D requires absolute calibration.
F: The requirements on the wind field for sea state determination normally exceed sampling requirements for wind forcing
G: High resolution SST from new geostationnary satellite + combination with low satellite