BEDMAP A new compilation of the bed topography under the Antarctic Ice sheet.

Sponsored by: European Ice Sheet Modelling Initiative Scientific Committee on Antarctic Research

Welcome
Welcome to the first project update for BEDMAP. Over the next 12 months we intend to publish regular updates on BEDMAP distributed by email to the BEDMAP consortium and all other interested parties. These updates will also be made available on the World Wide Web at the BEDMAP Home Page;
http://www.nerc-bas.ac.uk/public/aedc/bedmap/bedmap.html.

 Status
At the first BEDMAP Workshop in Cambridge in October 1996 three phases of work were identified;
(i) data collection and storage,
(ii) data compilation including evaluation and validation of the data,
(iii) product generation, i.e. the production of gridded data sets describing ice thickness and bedrock elevation.

 Since my appointment to BEDMAP Database Manager in July the first task has been the completion of the data model or format for BEDMAP data sets. This is described below in 'Database Design'. Once this task was completed we have begun the process of entering data into the system. The data sets currently stored within BEDMAP are briefly described in 'Data Collection'. Over the next 6-9 months most of the effort will be put into the first phase of the work - i.e. data collection and storage.

 Database Design
All source BEDMAP data will be stored within a relational database (Oracle) on a Unix system residing at the British Antarctic Survey. This database will be used as the principal repository for BEDMAP data. The data contributed to BEDMAP are divided into missions to allow broad groupings of similar data. The missions will generally consist of data from a group of sorties/flights for which acquisition parameters remained broadly similar. Each mission will have a metadata record stored in the Mission Summary Table describing methods in data collection, navigation, data logging, processing, source contacts, availability etc. The actual data will be stored in the Mission Data Table which fields include mission_id, sortie_id (flight number), latitude, longitude, ice thickness, surface elevation, bedrock elevation and internal references used to map back to the original data set. A third table, the Trackline Sortie Data Table, specific to trackline data will hold generalised track descriptions and be used to enable rapid geographic searches of the database.
 

Data Collection
Over the initial data collection and storage phase most of the focus has been on the recovery and incorporation of the United States oversnow seismic traverse data dating back to the International Geophysical Year. Data from 15 different missions have so far been incorporated into BEDMAP including seismic soundings carried out in a traverse from McMurdo Station to the South Pole in 1960-61, seismic and gravity observations in the Ellsworth Highlands in 1960-61, data from the Ross Ice Shelf Geophysical and Glaciological Survey (1973-78) and the Queen Maud Land. Traverses from 1964-68.

Other data incorporated so far include measurements from 7 Airborne RES missions in Enderby land, the Amery Ice Shelf, the Lambert Glacier and Wilkes Land carried out by Antarctic CRC/ Australian Antarctic Division. In addition to these data we have incorporated a large Airborne RES data set of Berkner Island, Ice Rises and Ice Rumples of Filchner-Ronne-Schelfeis & Ritscherhochland / Western Neuschwabenland collected by the University of Munster between 1985 and 1990. A summary of the data sets currently in the BEDMAP database is available.

Upcoming Activities
In the coming weeks the focus will be the incorporation of surface traverse data collected by the Japanese Antarctic Research Expeditions (JARE) between 1968 and 1992 in East Queen Maud Land. These data will complement the more recent JARE data to be provided by Shuji Fujita and Professor Fumihiko Nishio later on this year. Work will also begin on the task of reformatting the existing British Antarctic Survey Radio-Echo Sounding Database to comply with the BEDMAP data format. This database of digitised airborne radar sounding data holds data for around 280 flights between 1966 and 1987 - over 158,000 measurements.

Contact BEDMAP
Any feedback on the project or any queries regarding BEDMAP may be directed to Matt Lythe, or David Vaughan. The BEDMAP consortium encourages all scientists with appropriate data to participate in the project.