Ice Sheets - Capabilities and Requirements (from IGOS Cryosphere Theme Report)
|
Parameter
|
CT O |
Measurement Range |
Measurement Accuracy |
Resolution |
Comment / Principal Driver |
||||||
|
Spatial |
Temporal |
||||||||||
|
L |
H |
U |
V |
U |
V |
U |
V |
U |
|||
|
Ice margin |
C |
0 |
1000 |
km |
2 |
km |
2 |
km |
5 |
yr |
AVHRR |
|
T |
0 |
1000 |
km |
2 |
Km |
2 |
Km |
5 |
yr |
Hi-res optical and SAR |
|
|
O |
0 |
1000 |
km |
25 |
m |
25 |
m |
1 |
yr |
||
|
Grounding Line |
C |
0 |
1000 |
km |
1 |
km |
1 |
km |
5 |
yr |
|
|
T |
0 |
1000 |
km |
1 |
Km |
1 |
Km |
5 |
yr |
Hi-res optical/InSAR |
|
|
O |
0 |
1000 |
km |
100 |
m |
1 |
km |
1 |
yr |
||
|
Surface Accumulation |
C |
0 |
50 |
cm water eq/yr |
1 |
cm water eq/yr |
25 |
km |
1 |
yr |
Passive microwave, P/E/ models and in situ |
|
T |
0 |
50 |
cm water eq/yr |
1 |
cm water eq/yr |
25 |
km |
1 |
yr |
Active/ passive microwave |
|
|
O |
0 |
50 |
cm water eq/yr |
1 |
cm water eq/yr |
1 |
km |
6 |
mo |
||
|
Basal Melt Magnitude |
C |
0 |
20 |
m/yr |
100 |
cm/yr |
10 |
km |
1 |
yr |
Inferred |
|
|
T |
0 |
20 |
m/yr |
100 |
cm/yr |
10 |
km |
1 |
yr |
|
|
|
O |
0 |
20 |
m/yr |
10 |
cm/yr |
1 |
km |
6 |
mo |
|
|
Basal Melt Distribution |
C |
0 |
104 |
km2 |
1 |
km |
50 |
km |
1 |
yr |
|
|
T |
0 |
104 |
km2 |
1 |
km |
50 |
km |
1 |
yr |
UHF/VHF radar |
|
|
O |
0 |
104 |
km2 |
1 |
km |
10 |
km |
1 |
yr |
||
|
Surface Elevation |
C |
0 |
4 |
km |
50 |
cm |
1 |
km |
1 |
yr |
|
|
T |
0 |
4 |
km |
50 |
cm |
1 |
km |
1 |
yr |
Radar and laser altimeter |
|
|
O |
0 |
4 |
km |
50 |
cm |
1 |
km |
1 |
yr |
||
|
Surface Elevation Change |
C |
0 |
5 |
m/yr |
10 |
cm/yr |
5 |
km |
1 |
yr |
|
|
T |
0 |
5 |
m/yr |
10 |
cm/yr |
5 |
km |
1 |
yr |
Radar and laser altimeter |
|
|
O |
0 |
5 |
m/yr |
10 |
cm/yr |
1 |
km |
6 |
Mo |
||
|
Snow/Firn Density |
C |
0 |
910 |
kg/m3 |
50 |
kg/m3 |
100 |
km |
5 |
yr |
|
|
T |
0 |
910 |
kg/m3 |
50 |
kg/m3 |
100 |
km |
5 |
yr |
In situ obs |
|
|
O |
0 |
910 |
kg/m3 |
10 |
kg/m3 |
100 |
km |
5 |
yr |
||
|
Snow Grain Size and Shape |
C |
0.1 |
3 |
mm |
0.25 |
mm |
100 |
km |
5 |
yr |
Optical and in situ |
|
T |
0.1 |
3 |
mm |
0.25 |
mm |
100 |
km |
5 |
yr |
|
|
|
O |
0.1 |
3 |
mm |
0.25 |
mm |
100 |
km |
5 |
yr |
||
|
Surface Temperature |
C |
173 |
278 |
oK |
1 |
oK |
10 |
km |
1 |
yr |
In Situ |
|
T |
173 |
278 |
oK |
1 |
oK |
10 |
km |
1 |
yr |
Annual average THIR |
|
|
O |
173 |
278 |
oK |
1 |
oK |
10 |
km |
1 |
mo |
||
|
Internal Temperature |
C |
173 |
273 |
oK |
0.1 |
oK |
500 |
km |
5 |
yr |
|
|
T |
173 |
273 |
oK |
0.1 |
oK |
500 |
km |
5 |
yr |
Borehole temp. |
|
|
O |
173 |
273 |
oK |
0.1 |
oK |
500 |
km |
5 |
yr |
||
|
Gravity Field |
C |
|
|
|
2 |
mgal |
1 |
km |
1 |
yr |
|
|
T |
|
|
|
2 |
mgal |
1 |
km |
1 |
yr |
Airborne Gravity |
|
|
O |
|
|
|
0.5 |
mgal |
1 |
km |
1 |
yr |
||
|
Surface Velocity Field |
C |
0 |
15 |
km/yr |
10 |
m/yr |
1 |
km |
6 |
mo |
|
|
T |
0 |
15 |
km/yr |
10 |
m/yr |
1 |
km |
6 |
mo |
GPS and InSAR |
|
|
O |
0 |
15 |
km/yr |
10 |
m/yr |
1 |
km |
6 |
mo |
||
|
Vertical Velocity Variation |
C |
0 |
1 |
m/yr |
10 |
cm/yr |
100 |
km |
5 |
yr |
|
|
T |
0 |
1 |
m/yr |
10 |
cm/yr |
100 |
km |
5 |
yr |
Vertical strain gauges |
|
|
O |
0 |
1 |
m/yr |
10 |
cm/yr |
100 |
km |
5 |
yr |
||
|
Ice thickness |
C |
.010 |
4 |
km |
20 |
m |
50 |
km |
10 |
yr |
Ice sheet wide |
|
T |
.010 |
4 |
km |
20 |
m |
50 |
km |
10 |
yr |
VHF and UHF Radar |
|
|
O |
.010 |
4 |
km |
20 |
m |
1 |
km |
10 |
yr |
||
|
Internal Layer Depth |
C |
.010 |
4 |
km |
20 |
m |
50 |
km |
10 |
yr |
|
|
T |
.010 |
4 |
km |
20 |
m |
50 |
km |
10 |
yr |
VHF and UHF radar |
|
|
O |
.010 |
4 |
km |
20 |
m |
1 |
km |
10 |
yr |
||
|
Iceberg calving rate |
C |
0 |
30 |
km/yr |
1 |
km/yr |
1 |
km |
1 |
yr |
Inferred |
|
T |
0 |
30 |
km/yr |
1 |
km/yr |
1 |
km |
1 |
yr |
|
|
|
O |
0 |
30 |
km/yr |
1 |
km/yr |
1 |
km |
6 |
mo |
||
|
Changes in ice sheet morphology (crevasses, shear margins) |
C |
0 |
100 |
m |
100 |
m |
1 |
km |
1 |
yr |
|
|
T |
0 |
100 |
m |
100 |
m |
1 |
km |
1 |
yr |
Hi Res optical and InSAR |
|
|
O |
0 |
100 |
m |
100 |
m |
1 |
km |
1 |
yr |
||
|
Surface melt extent |
C |
0 |
20 |
106sq km |
2500 |
km2 |
25 |
km |
1 |
day |
|
|
T |
0 |
20 |
106sq km |
2500 |
km2 |
25 |
km |
1 |
day |
Passive and active microwave |
|
|
O |
0 |
20 |
106sq km |
400 |
km2 |
10 |
km |
1 |
day |
||
|
Surface melt duration |
C |
0 |
100 |
Melt days |
1 |
Melt day |
25 |
km |
1 |
day |
|
|
T |
0 |
100 |
Melt days |
1 |
Melt day |
25 |
km |
1 |
day |
Passive and active microwave |
|
|
O |
0 |
100 |
Melt days |
1 |
Melt day |
1 |
km |
1 |
day |
||
|
Ice Sheet Mass Change |
C |
0 |
200 |
km3/yr |
50 |
km3/yr |
500 |
km |
1 |
yr |
Flux approach not included in this category |
|
T |
0 |
200 |
km3/yr |
50 |
km3/yr |
500 |
km |
1 |
yr |
Satellite Gravity |
|
|
O |
0 |
200 |
km3/yr |
10 |
km3/yr |
500 |
km |
1 |
yr |
||
|
Geothermal Heat Flux |
C |
0 |
1 |
w/m2 |
1 |
w/m2 |
1000 |
km |
10 |
yr |
|
|
T |
0 |
1 |
w/m2 |
1 |
w/m2 |
1000 |
km |
10 |
yr |
TBD approach |
|
|
O |
0 |
1 |
w/m2 |
1 |
w/m2 |
100 |
km |
10 |
yr |
||
Codes are as follows: C = Current Capability, T = Threshold Requirement (Minimum necessary), O= Objective Requirement (Target), L = Low end of measurement range, U = Unit, H = High end of measurement range, V = Value, cl = climate, op = operational.