Prof. Duncan Wingham, CryoSat Lead Investigator

Objectives and opportunities for shared CryoSat-2

Icebridge experiments

“CryoSat will, in its own lifetime, determine whether the present observed changes in

sea ice signal important changes in Arctic climate or merely the ephemera of inter-

annual variability at short spatial scales; and reduce the uncertainty in the ice sheet

contribution to sea level to a magnitude similar to that associated with other sources of

sea level rise”

The CryoSat Science and Measurement Requirements.Requirement Arctic Sea Ice 105 km2 Ice Sheets 104 km2 Ice Sheets 13.8 x 106 km2

σ r

( ηr

) 3.5 cm yr-1 i.e. 8.3 cm yr-1 i.e. 0.76 cm yr-1 i.e. (92 Gt yr-1)

σ m 1.6 cm yr-1 3.3 cm yr-1 0.17 cm-1

CryoSat Mission Requirements

σ r2 =σ n

2+σ m2

Mission Status

-0.6˚ 0.6˚0.0˚ degrees

0.0˚

0.01˚

-0.01˚

Interferometer Error

Courtesy: Marco Fornari

Pritchard et al., Nature., 2009Wingham, Phil. Trans. Roy. Soc, 2006

Mission Cross-calibration

Sources of ErrorError in spatially averagedice sheet mass imbalance.

Covariance of uncertain snowfall fluctuation

Covariance of uncertain near surface density

Covariance of elevation trend error

Covariance of retrieval error

Covariance of instrument system error

Time-variant penetration error

Atmospheric refraction error

Intersatellite bias

Echo delay time error

Radial orbit error

Echo direction error

Datation Error

Speckle-errors

Timing (and other) drifts

Tidal forcing errors

Post-glacial rebound error

Determination of surface accumulation and its variability.

Hawley et al., Geophys. Res. Lett, 2006 de la Pena et al., Cryosphere, 2010

CryoSat Validation Locations

Coordination & Data Sharing

• The CryoSat-2 CVRT is a group selected by an ESA AO process. Its activities are cost shared

(approximately 6 M€ for CryoSat-2), approximately 1/3rd ESA and 2/3rds national agencies.

• The multitude logistics and funding constraints make multi-year, detailed planning impractical.

The CVRT operates through broadly agreed scientific goals, implemented through on-going,

twice-per-year meetings that plan the upcoming year’s activities, taking opportunistic advantage of

logistics and funding.

• The CVRT operates a (non-satellite) data sharing arrangement in which the ‘ground’ observations

are pooled in ‘exchange’ for the airborne data. We allow a reasonable, but not prolonged, period

for individual groups to publish individual results prior to data sharing. It is generally agreed that

when individuals use ‘pooled’ data the group that provided the data is credited with authorship on

publications. There is no agreement, today, to make data available to any user; equally, there would

probably be no objection to doing so after a reasonable (2 year?) interval.

• The next meeting of the CVRT is 3 February 2011 at ESRIN (Frascati, Italy), immediately following

the CryoSat-2 workshop.