First German CryoSat User Workshop

Bremerhaven, May 28/29, 2001

Contents page

1. Major results 1

2. First draft of a user concept 1

Attachment 1: List of participiants 5

Attachment 2: Workshop-Agenda 6

1. Major results

During the workshop, participants expressed their interests in different aspects of the mission. These are listed below in the user concept. Apart from this, the workshop revealed some problems in using CryoSat data, which were mainly due to missing information. Although this is probably due to the early state of the mission and the tight schedules in mission preparations, the major open questions are listed below as a reference for the CryoSat SAG:

Currently, users are largely lacking information: SAG should define a number of key documents with respect to technical information, orbit information, data product information, data distribution information.

Who defines level 2 products?

Level 2: what is the error budget, is it available to the user?

Geocoding: orbit or footprint oriented?

There is large interest in obtaining information about surface properties. What kind of information will be available?

Experience with other radar altimeter data shows that corrections applied to the data have to be documented very carefully and detailed.

What are the relevant regional scales for validation campaigns?

It would be most welcome to have repeated overflights at certain locations on the Antarctic peninsula, to make use of the SIRAL advantages on some of the most rapidly changing glaciers and ice sheets. Could certain orbit phases be planned for this, e.g. during validation orbits?

2. First draft of a user concept

Due to the major goals of CryoSat, observations of both land ice and sea ice, CryoSat users have a wide range of different approaches to use CryoSat data. There are many different applications of the data, employing different data product levels. Although only preliminarily defined by ESA or the SAG, data products are reviewed in Figure 1. The following paragraphs will always refer to that Figure.

Table 1, designed as a German user concept of CryoSat data, is structured according to these different user groups and levels.

In the table, first land and sea ice applications are differentiated. Although the ultimate question to be answered with CryoSat data, the observation of changes in the mass budgets of ice shields and the sea ice cover is the same for both ice types, the temporal and spatial scales as well as the means of interpretation of results are quite different. This has to be taken into account by a user concept.

Second, CryoSat data are used at different levels for different applications. Broad interest exists in Germany with respect to validation activities. As can be seen from Figure 1, those groups are interested in a variety of data levels, ranging from almost raw data to the final level 2-3 products. In general remote sensing applications, CryoSat data will be used as complementary information for integrated studies involving other satellite data like from ENVISAT, RADARSAT, ASTER, Quickscat, Jason or DMSP. Like with validation activities, using additional other remote sensing data will also enable the development of new algorithms to extract other geophysical data from CryoSat than primarily surface height. In the case of sea ice, this might e.g. be ice concentration or surface roughness. The development of these algorithms corresponds to level 1 to 2 processing. Another user group is interested in looking at confined regions to perform process studies, like the temporal evolution of the sea ice thickness distribution in a certain region, or mass changes of certain glaciers. These groups will only employ level 2 or 3 data. Finally, there is a group of real "end-users" who are applying or exploring the complete, gridded data set (level 3&4). These groups consist mainly of modelers, who will use the derived fields as boundary conditions for their models, e.g. Digital Elevation Models (DEMs), to validate their model results, or to assimilate gridded data into the models. This group will be accompanied by scientists who will look at the statistical behaviour of the derived elevations and thicknesses, to finally assess where and whether the polar ice masses are growing or shrinking.


Figure 1: Preliminary presentation of planned CryoSat data products (from CryoSat SAG).

Apparently, in Germany there is no interest to work on the more electrical-engineering side, like in the development of retrackers, or in data processing from level 0 to level 1b data.

A major expectation is the better accuracy of CryoSat data in general compared to older RA data. Furthermore, it is hoped that CryoSat will extend the data base into formerly unmeasureable regions with rough or steep topography which could not be mapped by old-style RAs. A major improvement of RA related activities is of course the extension of the orbit coverage up to 88°N and S.

The table is structured for temporal sequence of activities. First, validation will be performed before the accuracy of the data can be judged and the can be made available to others. Then, the data can already be used for remote sensing and process studies. Finally, after gridding and data collection over longer periods, the derived fields can be used for modeling and statistical exploitation.

Table 1: User concept for CryoSat data
Application / Approach Scientific question Geographic region of interest Data products Institutions
Validation In-situ height surveys in key regions ((D)GPS, aircraft laser altimetry) King George Island

Filchner Ronne Ice Shelf

Ekström Ice Shelf

Schirmacher Oasis

Level 2 Uni DD, Uni FR, Uni MS, AWI
  Dry vs. wet snow conditions and their influence on height retrievals   s0 Uni FB, AWI
  In-situ airborne sub-satellite sea-ice thickness and roughness profiling   Level 2, s0 AWI
Remote sensing Dry vs. wet snow conditions and their representation in CryoSat data Antarctic Peninsula, Antarctic continental rims, Greenland Level 2 at different seasons Uni MS, Uni FR, AWI
  Deterioration of ice shelves, retreat of glacier fronts, snow zones/facies Antarctic Peninsula Level 2, s0 Uni FR
  Derivation of snow accumulation and thickness on sea ice from other (e.g. passive microwave) data for improvement of thickness estimates Arctic Ocean, Southern Ocean Level 1b & 2 Uni HB
  Development of algorithms for the retrieval of ice concentration Arctic Ocean, Southern Ocean Level 0-1b, s0 Uni HB, AWI
  Development of algorithms for the retrieval of ice surface roughness Arctic Ocean, Southern Ocean Level 0-1b, s0 DLR, AWI
Process studies Change of glacier mass budget after major downstream calving E.g. Drygalski Glacier (Antarctic Peninsula) Level 2 Uni FR
  Change of ice shelf thickness, deduction of bottom melting rates E.g. Filchner-Ronne Ice Shelf, Twaites Glacier Level 2 Uni MS, DLR, AWI
  Determination of different glacier facies Greenland s0 Uni TR
  Development of sea-ice thickness distribution under different atmospheric forcing regimes Arctic Ocean, Southern Ocean Level 0-2 AWI
Level 3 data generation Application of specially adapted geo-mathematical techniques: kriging, regional kriging, and cokriging   Level 2 Uni TR
Modeling RA data as boundary condition for ice sheet models Antarctic continent, Antarctic peninsula, Greenland High resolution DEM, level 3 Uni MS, Uni DA, AWI
  Detection of grounding lines from tidal displacements Antarctica Level 2 Uni MS, Uni DA, AWI
  Assimilation of sea-ice thickness into regional and large scale sea ice models Arctic Ocean, Southern Ocean Level 2 & 3 AWI
  Validation of model results (spatial and temporal patterns) Arctic Ocean, Southern Ocean Level 2 & 3 AWI
Geodesy Derivation of the geoid over ice covered oceans Arctic Ocean, Southern Ocean Level 3 & 3 TUM
Statistical exploitation Monitoring of changes in surface height in large regions   Level 2 & 3 Uni MS, AWI
  Extension of available mass-balance time series derived from other sources   Level 2 & 3 Uni DD, Uni FR, Uni TR, AWI
  Monitoring of changes in sea-ice thickness in large regions   Level 2 & 3 AWI


AWI: Alfred Wegener Institute of Polar and Marine Research, Bremerhaven

Uni DA: Mechanical Institute, Technical University Darmstadt

Uni DD: Geodetical Institute, University of Dresden

DLR: German Aerospace Center, Oberpfaffenhofen

Uni FR: Institute for Physical Geography, University of Freiburg

Uni HB: Institute of Environmental Physics, University of Bremen

Uni MS: Geophysical Institute, University of Münster

Uni TR: Geographical Institute, University of Trier

TUM Geodetical Institute, Technical University of München

Attachment 1: List of participiants
Reinhard Dietrich Inst. f. Planetare Geodäsie Universität Dresden
Mark Drinkwater ESTEC Earth Sciences Division
Jakob Flury GOCE-Projektbüro Deutschland Inst. f. Astr. und Phys. Geodäsie
Oliver Funke Inst. f. Umweltphysik Universität Bremen
Hermann Goßmann Inst. f. Physische Geographie Universität Freiburg
Ralf Greve Institut fuer Mechanik TU Darmstadt
Klaus Grosfeld Inst. f. Geophysik Universität Münster
Christian Haas Alfred-Wegener-Institut
Ute C. Herzfeld FB6 Geowissenschaften Universität Trier
Georg Heygster Inst. f. Umweltphysik Universität Bremen
Ralf Krocker Alfred-Wegener-Institut
Thomas König DLR
Gert König-Langlo Alfred-Wegener-Institut
Susanne Lehner DLR
Peter Lemke Alfred-Wegener-Institut
Wolfgang Lengert ESA-ESRIN
Jan Lieser Alfred-Wegener-Institut
Uwe Mallow Astrium GmbH
Heinrich Miller Alfred-Wegener-Institut
Hans Oerter Alfred-Wegener-Institut
Helge Rebhan ESTEC Earth Sciences Division
Klaus Reiniger DLR
Friedhelm Rostan Astrium GmbH
Klaus-Peter Schmidt DLR
Jens Schröter Alfred-Wegener-Institut
Daniel Steinhage Alfred-Wegener-Institut
Ralf Stosius FB6 Geowissenschaften Universität Trier
Klaus Strübing BSH Eisdienst
Bernd Vennemann DLR
Martin Wiehl Inst. f. Planetare Geodäsie Universität Dresden
Duncan Wingham University College London
Klaus Zahnen Geographisches Institut Humboldt-Universität zu Berlin

Attachment 2: Agenda

Montag, 28.05.2001, AWI Gebäude F, Bussestrasse 24
13:00 - 13:30 Begrüssung, Aufgaben und Ziele des Projektbüros C. Haas, AWI 
K. Schmidt, DLR
13:30 - 13:50 CryoSat - The first mission of the Earth Observation Envelope Programme M. Drinkwater, ESA
13:50 - 14:15 Scientific goals of the CryoSat mission D. Wingham, UCL
14:15 - 15:00 CryoSat Raumsegment und Ablauf der industriellen Aktivitäten U. Mallow, Astrium
  SIRAL (Synthetic-Aperture Interferometric Radar Altimeter): Aufbau, Funktion und Kalibration F. Rostan, Astrium
15:00 - 15:20 Kaffeepause  
15:20 - 16:30 Status Cal/Val, Processing/Archiving, Level 2, AO's H. Rebhan, ESA
16:30 - 17:30 Arbeit der SAG (Scientific Advisory Group); Aspekte/Anforderungen von Landeismessungen H. Miller, AWI
  Cal/Val-Aktivitäten, Aspekte/Anforderungen von Meereismessungen P. Lemke, AWI
17:30 - 17:45 Das neue hochaufloesende Schwerefeld aus der GOCE-Mission 
als Beitrag zur Eisforschung?
J. Flury, GOCE-Projektbuero D
18:30 gemeinsames Abendessen / Buffet  

Dienstag, 29.05.2001, AWI Gebäude F, Bussestrasse 24
09:00 - 12:30 Erarbeitung der Anforderungen deutscher Nutzer an Datenprodukte. 
Beiträge deutscher Institutionen zur Schaffung höherwertiger Datenprodukte. 
Möglichkeiten und Interessen deutscher Gruppen zu Cal/Val-Aktivitäten.
12:30 - 13:00 Imbiss