ANNEX II
Tabulated Observational Data Requirements for GOOS/GCOS
Table A
A summary of the sampling requirements for the global ocean, based largely on OOSDP (1995), but with revisions as appropriate. These are a statement of the required measurement network characteristics, not the characteristics of the derived field. The field estimates must factor in geophysical noise and unsampled signal. Some projections (largely unverified) have been included for GODAE.
Sampling Requirements for the Global Ocean |
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Code |
Application |
Variable |
Hor. Res. |
Vert. Res. |
Time Res. |
#samples |
Accuracy |
A |
NWP, climate, mesoscale ocean |
Remote SST |
10 km |
- |
6 hours |
1 |
0.1-0.3°C |
B |
Bias correction, trends |
In situ SST |
500 km |
- |
1 week |
25 |
0.2-0.5°C |
C |
Climate variability |
Sea surface salinity |
200 km |
- |
10 day |
1 |
0.1 |
D |
Climate prediction and variability |
Surface wind |
2° |
- |
1-2 day |
1-4 |
0.5-1 m/s in components |
E |
Mesoscale, coastal |
Surface wind |
50 km |
- |
1 day |
1 |
1-2 m/s |
F |
Climate |
Heat flux |
2° x 5° |
- |
month |
50 |
Net: 10 W/m2 |
G |
Climate |
Precip. |
2° x 5° |
- |
daily |
Several |
5 cm/month |
H |
Climate change trends |
Sea level |
30-50 gauges + GPS with altimetry, or several 100 gauges + GPS |
- |
monthly means |
1 cm, giving 0.1 mm/yr accuracy trends over 1-2 decades |
|
I |
Climate variability |
Sea level anomalies |
100-200 km |
- |
10-30 days |
~ 10 |
2 cm |
J |
Mesoscale variability |
Sea level anomalies |
25-50 km |
- |
2 days |
1 |
2-4 cm |
K |
Climate, short-range prediction |
sea ice extent, concentration |
~ 30 km |
- |
1 day |
1 |
10-30 km 2-5% |
L |
Climate, short-range prediction |
sea ice velocity |
~ 200 km |
- |
Daily |
1 |
~ cm/s |
M |
Climate |
sea ice volume, thickness |
500 km |
- |
monthly |
1 |
~ 30 cm |
N |
Climate |
surface pCO2 |
25-100 km |
- |
daily |
1 |
0.2-0.3 µatm |
O |
ENSO prediction |
T(z) |
1.5° x 15° |
15 m over 500 m |
5 days |
4 |
0.2°C |
P |
Climate variability |
T(z) |
1.5° x 5° |
~ 5 vertical modes |
1 month |
1 |
0.2°C |
Q |
Mesoscale ocean |
T(z) |
50 km |
~ 5 modes |
10 days |
1 |
0.2°C |
R |
Climate |
S(z) |
large-scale |
~ 30 m |
monthly |
1 |
0.01 |
S |
Climate, short-range prediction |
U(surface) |
600 km |
- |
month |
1 |
2 cm/s |
T |
Climate model valid. |
U(z) |
a few places |
30 m |
monthly means |
30 |
2 cm/s |
(Top of
page)
Table B
Ocean Remote Sensing Requirements
OBSERVATIONS |
OPTIMIZED REQUIREMENTS |
THRESHOLD REQUIREMENTS |
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| Code | Application | Variable | Type | Horizontal scale (km) | Cycle | Time | Accuracy | Horizontal scale (km) | Cycle | Time | Accuracy |
ALTIMETRY |
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| A | Mesoscale Variability | Sea Surface Topography | input | 25 | 7 days | 2 days | 2 cm | 100 | 30 days | 15 days | 10 cm |
| B | Large-scale
Variability (seasonal, tides, gyres) |
Sea Surface Topography | input | 100 | 10 days | 2 days | 1 cm | 300 | 10 days | 10 days | 2 cm |
| C | Mean Sea Level Variations | Sea Surface Topography | input | 200 | decades | 10 days | 1 mm/year | 1000 | decades | 10 days | 5 mm/year |
| D | Absolute
Circulation Heat Transport |
Sea Surface Topography | input | 100 | N/A | N/A | 1 cm | 500 | N/A | N/A | 5 - 10 cm |
| E | Geoid Estimation | Geoid | Base | 100 | N/A | N/A | 2 cm | 500 | N/A | N/A | ~ 1 cm |
SURFACE WIND VECTORS |
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| F | Wind-forced Circulation | Wind field | input | 25 | 1 day | 1 day | 1-2 m/sec. 20° |
100 | 7 days | 7 days | 2 m/second 30° |
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 in addition, precise positioning system with an accuracy of 1-2 cm for a spatial resolution of 100 km.; need to address aliasing from solar tides with non-sun-synchronous orbits. |
| C | requires, in addition, 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: at least 2, and better 3, satellites simultaneously. |
| A, B and C | require long lifetime, continuity, cross calibration. |
| D | requires absolute calibration. |
| E | requires one-off missions with both high- and broad-resolution determination. |
| F | Wind field requirements for sea state determination normally exceed sampling requirements for wind forcing. |
Table B of Ocean Remote Sensing Requirements
(continued)
OBSERVATIONS |
OPTIMIZED REQUIREMENTS |
THRESHOLD REQUIREMENTS |
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| Code | Application | Variable | Type | Horizontal scale (km) | Cycle | Time | Accuracy | Horizontal scale (km) | Cycle | Time | Accuracy |
SEA SURFACE RADIATIVE |
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| G | Ocean/ Atmosphere coupling |
Sea Surface Temperature (Radiometer) | input | 10 | 6 hours | 6 hours | 0.1 K (relative) | 300 | 30 days | 30 days | 1 K |
| H | Ocean Forcing | Short wave irradiance | input | 200 | 1 day | 1 day | 15 W/m2 | 500 | 7 days | 7 days | 20-30 W/m2 |
REMOTE SALINITY |
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| I | Circulation and Water Transport | Salinity | input | 200 | 10 days | 10 days | 0.1 PSU | 500 | 10 days | 10 days | 1 PSU |
SEA ICE |
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| J | Ice-Ocean Coupling | Sea Ice Cover | input | 10 | 1 day | 3 hours | 2% | 100 | 7 days | 1 day | 10% |
OCEAN COLOUR |
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| K | Upwelling to Recirculation | Ocean Colour Signal | input | 25 | 1 day | 1 day | 2% | 100 | 1 day | 1 day | 10% |
SURFACE WAVES |
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| L | Sea State Prediction | Significant Wave Height | input | 100 | 3 hours | 3 hours | 0.5 meters | 250 | 7 days | 12 hours | 1 meter |
| M | Sea State prediction | Period and Direction | input | 10 | 1 hour | 2 hours | ½ second 10° |
30 | 6 hours | 4 hours | 1 second 20° |
| Footnotes: | G requires high resolution sea surface temperature: new geostationary
satellite + combination with low satellite. The requirements include consideration of climate applications as determined by the OOPC and ocean forecasting/estimation as determined by GODAE. The requirements beyond the climate module have not been detailed here. |
