1. Objectives of Meeting
• Present/review validation activities.
• Hear what PI’s are doing and intend to do with the products
• Coordinate production/distribution of RGPS data products
2. General Issues

• The RADARSAT MOU (Memorandum of Understanding) expires on November 4, 2000. After that date, U.S. researchers will not be able to request new RADARSAT acquisitions - there will be no more Arctic Snapshots. The chair of the RGPS Science Working Group (Drew) will draft a letter to Ghassem Asrar emphasizing the importance of extending of the RADARSAT MOU.

• Also note: there is a planned ice stress field experiment (sponsored by ONR/NOAA/CRREL) during the winter of 2000/2001. RGPS data set is critical to this program.

• NASA and ESA are negotiating a MOU for access to ENVISAT data from all its sensors, including the Advanced SAR (ASAR). ENVISAT is scheduled for launch in June 2001. Kim is optimistic about NASA and ESA reaching an agreement. The main item of negotiation is the cost of the data to NASA. Kim is taking an action to make sure the NASA/ESA negotiators are aware of our desire to continue the Arctic Snapshot with ASAR, as this will be a major data acquisition program. We (the RGPS Science Working Group) also need to involve European investigators in this EGPS (ENVISAT Geophysical Processor System) so they can lobby ESA from the inside. Ron Kwok and Ben Holt traveled to Toulouse last fall to present the idea to ESA and the Europeans.

• A NASA press release is needed to publicize the RGPS. JPL/ASF will work on a video (animation/graphics) for the release. The RGPS Science Working Group will work on text (Drew and Ron). The material should be targeted to the general public. Some points to note: (1) SAR sees the surface in day/night/all-weather conditions; (2) unprecedented mapping of the Arctic ice cover at 3-day intervals throughout a full fall-winter-spring cold season; (3) the significance of the observations in relation to recent changes in Arctic ice thickness and extent.

 

3. Summary of Recommendations of RGPS SWG
• RGPS Data Processing Priorities

• The JPL RGPS plans to finish the 1996-97 season (extending into June 1997) within the ASF mask within a month or two. The JPL RGPS will turn to the summer of 1998 (in the ASF mask). A new 10-km grid will be initialized. Tracking and product generation will proceed from the time just after the onset-of-melt until fall freeze-up. This will take about five to six months. Following that, the JPL RGPS will process Tromso data from the winter of 1997-98, in the usual way (Lagrangian 10-km grid). This will take three to four months. Thus in about one year, the entire SHEBA year (fall 1997 to fall 1998) will have been processed: ASF and Tromso masks, winter and summer, perennial and seasonal ice zones.

• The ASF RGPS will continue with fall-winter-spring 1997-98 production within the ASF mask. Tracking will proceed through the onset of melt and into June (1998), to provide overlap with summer products (see below). This will be completed by about September 2000. The ASF RGPS will then go back and create products for the seasonal ice zone within the ASF mask for 1997-98. A new 25-km grid will be initialized at a date when the seasonal ice zone is frozen, sometime around December 15, 1997. This grid will be tracked and the usual products computed as with the perennial ice zone.

• AMM-2 is scheduled for September-November 2000. Once AMM-2 starts, it will monopolize ASF Level 1 production for a long time. Therefore ASF needs to look ahead and plan to process enough Level 1 imagery before AMM-2 so that both RGPS systems have the input imagery they need to continue production.

• Data Products

• Ron Kwok and Ron Lindsay will work out some minor changes to the products and their format as suggested in the validation report. (The RGPS validation report is available as a PDF file at the RGPS Validation web site http://psc.apl.washington.edu/RGPS/validation/ )

• The backscatter, age, and thickness products will each be re-packaged into one file per stream per month. Currently these products have one file every three days, so this change will reduce the number of files by a factor of eight to ten.

• The Lagrangian ice motion and deformation products will remain cumulative, with each new product (one per stream per cycle) containing all the information up to that time.

• The "connectivity table" will be a new product. This table contains the trajectory ID numbers for the vertices of each cell.

• The documentation and variable names should distinguish between quantities that are actually observed and those that are derived. For example, the Lagrangian ice motion trajectories are observations (at least as accurate as buoy positions), whereas the ice thickness histograms are derived from assumptions about ice growth involving freezing-degree-days.

• All the products are currently Lagrangian, following the cells as they drift in space, and computed at the SAR image times. We talked about producing Eulerian products on a fixed spatial grid and at fixed time intervals. The motivation is to make the products easier to use. Concern was expressed about the loss of information that would necessarily result from the interpolations. In the end we decided to produce monthly summary products on a fixed 50-km Eulerian grid for ice motion, deformation, backscatter, age, and thickness.

• New products containing the dates of melt onset and freeze-up should be produced. Each of these would be computed on a 50-km Eulerian grid containing the date of the event in each grid box. Melt onset and freeze-up are detected by changes in the radiometry of the SAR images.

• The IABP (International Arctic Buoy Program) wind fields and POLES (Polar Exchange at the Sea Surface) 2m air temperature fields will soon be available as new products. These data are used by RGPS and are available elsewhere, but will be issued by RGPS for the convenience of the users.

• Data Distribution

RGPS products will be distributed in three ways:

• Via the web/ftp as currently available from the JPL web site. The ASF web site will be ready at the end of February.

• Via the EDG (EOSDIS Data Gateway) as all other products from ASF are available. RGPS products will be added in March.

• Via CD-ROM subscription service. Products for a full season could be sent out to a list of subscribers when the processing for that season is done. ASF is implementing CD-ROM production capability for AMM-1 anyway, so there is no development cost to RGPS for this method of data distribution.

4. Ross Sea - RGPS demonstration

The feasibility of Antarctic RGPS products for the Ross Sea should be tested. Ron Kwok will devise an acquisition plan for 3-day coverage lasting for several cycles, to be acquired during the austral winter of 2000, or at least before the satellite eclipse period in July. Nettie will look at allocation issues associated with this large data acquisition request. These tasks must be accomplished in the next month or two. No timetable was worked out for actually processing the RADARSAT data into images or processing the images into RGPS products. The most important task at this point is to acquire the data. Ron Kwok will contact the Southern Ocean investigators who will be interested in this data set.

The RGPS SWG wishes to thank Koni Steffen for hosting the meeting at CIRES, University of Colorado, Boulder, CO. The summary here is based on the notes taken by Harry Stern.

T. Arbetter U of Colorado arbetter@monsoon.colorado.edu

R. Barry U of Colorado rbarry@kryos.colorado.edu

T. Bicknell JPL tom.bicknell@jpl.nasa.gov

J. Curry U of Colorado curryja@cloud.colorado.edu

M. Coon NWRA max@nwra.com

J. Crawford JPL john.crawford@jpl.nasa.gov

R. Fatland Vexcel rob.fatland@vexcel.com

G. Flato U of Victoria greg.flato@ec.gc.ca

F. Fetterer NSIDC fetterer@kryos.colorado.edu

W. Hibler III IARC billh@gi.alaska.edu

B. Holt JPL ben.holt@jpl.nasa.gov

M. Hopkins CRREL hopkins@crrel.usace.army.mil

R. Kwok JPL ron.kwok@jpl.nasa.gov

N. LaBelle Hamer ASF nettie@asf.alaska.edu

R. Lindsay PSC/U of Washington lindsay@apl.washington.edu

J. Maslanik U of Colorado jimm@northwind.colorado.edu

J. Overland PMEL overland@pmel.noaa.gov

T. Papakyriakou U of Manitoba tim_papakyriakou@umanitoba.ca

K. Partington NASA kparting@hq.nasa.gov

D. Rothrock PSC/U of Washington rothrock@apl.washington.edu

E. Schulson Dartmouth erland.m.schulson@dartmouth.edu

V. Sloan U of Colorado sloanv@klima.colorado.edu

K. Steffen U of Colorado koni@seaice.colorado.edu

H. Stern PSC/U of Washington harry@apl.washington.edu

R. Weaver NSIDC weaver@kryos.colorado.edu

Y. Yu PSC/U of Washington yanling_yu@apl.washington.edu