State of Passive Microwave Polar Stereographic Products. Walt Meier and polar stereographic product team

Transcription

1 State of Passive Microwave Polar Stereographic Products Walt Meier and polar stereographic product team

2 State of PM PS datasets NRT Tb and sea ice running nominally after many issues (see subsequent slides) Wentz Tb and NSIDC preliminary data updated through December 2008 behind due to sensor/satellite/processing issues (see subsequent slides) Goddard Final Sea Ice products updated through December Snow Melt Onset over Sea Ice product reprocessed to a Version 2, updated through 2007 Working with PI (C. Fowler) on Sea Ice Motion update will include AMSR-E input field

3 Last 1+ Years, NRT Tb and sea ice Several issues have been dealt with on an almost continuing basis: Jan 2008 F13 starts showing some significant data gaps Mar 2008 F13 data gaps become worse, more persistent Cause was loss of one of the data recorders Apr 2008 Switch made to F15 (Jan-Mar reprocessed with F15) Needed to correct for bias in 22 GHz from a radcal beacon that DoD had turned on in August 2006 Tiepoints adjusted for F15-F13 sensor differences Nov 2008 Start investigating acquisition of F17 SSMIS NRT data from NOAA CLASS SSMIS data not available from NASA Marshall, source for SSM/I NRT data

4 Last 1+ Years, NRT Tb and sea ice, cont. Feb 2009 F15 sea ice shows sudden dropout of sea ice Problem traced to 22 GHz, due effect of solar angle on radcal beacon Feb 2009 F13 reinstated for NRT Tb and sea ice data gaps had been minimized over the year Jan-May 2009 slow progress on F17 due to new data source, new format, limited documentation, limited user service through CLASS May 2009 Second recorder on F13 fails, numerous data gaps Transition to F17 ramped up to top priority Jun 2009 A week after F13 failure, F17 is put into production New tiepoints derived based on 1-year intersensor calibration first ever on-the-fly NRT intersensor calibration for sea ice products?

5 Last 1+ Years, NRT Tb and sea ice, cont. Jul 2009 Problem found with 37H GHz channel of F17 SSMIS, causing large biases in snow product (did not affect sea ice products) F17 37H Tbs found to be biased low by ~3-4 K. Problem started in early April Difficult to find proper contacts to alert and find information, but eventually we reached FNMOC and NOAA ops Problem due to calibration ranges that were too restrictive, resulting in cutoffs of calibration values and thus biases in Tbs Aug 2009 Calibration cutoffs reset to remove bias, four months after problem first occurred, two weeks after NSIDC notified them of the problem. Not sure if the timing was a coincidence. No answer yet on whether the bad data will be reprocessed or not. Aug 2009 Problem with 91 GHz channel discovered. Location for higher resolution data in different location of CLASS file from rest of channels. Not well-documented in CLASS. NSIDC reprocesses F17 NRT 91 GHz data

6 Last 1+ Years, RSS Tb F13/F15 Mar With degradation of F13 starting in Jan 2008, NSIDC started investigating switching RSS source from F13 to F15 Jul 2008 RSS provided NSIDC with F15 data, including overlap period RSS instituted correction for F15 22 GHz channel, but 22 GHz data not deemed suitable as a CDR-level product. 22 GHz channel only used Aug-Nov 2008 NSIDC evaluates F15, but waits to do full processing in hopes that F17 SSMIS will be available from RSS soon (original estimate in Jul 2008 was 2-3 months) Try to avoid doing a double intercalibration of F13 F15 F17, instead of a single intercalibration of F13 F17 F17 launch in Nov 2006; earliest available data starting in Mar 2008

7 Last 1+ Years, RSS Tb, cont. F15/F17 Feb 2009 failure of F15 data due to 22 GHz radcal sun angle issue. NSIDC decides to not expend further resources on F15, but wait for F17 from RSS (Feb 2009 estimate of 2-3 more months) F17 chosen over F16 because (1) newer sensor, (2) better agreement with F13 orbit (ascending node crossing time) Sep 2009 RSS informs NSIDC beta version of F16 SSMIS available to test; F17 will be another 2-3 months

8 Last 1+ Years, RSS Tb, cont. RSS V4 vs. V6 Mar 2009 RSS informs NSIDC that they will no longer provide Version 4 data, but only Version 6 Jan-Jun 2008: Version 4 and Version 6 provided Jul : Only Version 6 available V4-V6 differences: o V4 had option to turn on or off intersensor calibration had always left it turned off as the calibration did not improve sea ice/snow products o V6 has improved geolocation Jun-Jul 2009 NSIDC does comparison of V4 vs V6 Most differences < 1K Areas where larger differences occurred were along coasts and the ice edge. Likely due to geolocation difference NSIDC decides to not perform any intercalibration for the version switch, denotes Tbs from new RSS version as NSIDC Version 3 NSIDC notifies Goddard of version switch and provides data for them to decide what intercalibration is needed for final sea ice products

9 Last 1+ Years, RSS Tb, cont. RSS V4 vs. V6 Jul 2009 RSS supplies NSIDC with F13 V6 back to beginning of record (1995) Resources limited to reprocess so much data at this point Goddard would need to redo F11-F13 intercalibration for sea ice Aug 2009 Additional period of F11 for Oct 1995 June 1996 discovered at NSIDC. Could process at some point, but not high priority at the moment.

10 Last 1+ Years, Goddard Sea Ice Products updated through Dec 2007 Products for 2008 delayed due to RSS V4/V6 issue Hope to have by the end of the year Aug Bootstrap algorithm acquired from Comiso, but implementation delayed by priorities with NRT and RSS data

11 Last 1+ Years, Other Products Snow Melt Onset Over Sea Ice Update/reprocessing provided Jan 2009 o Uses reprocessed Tbs (Version 2) o Updated through 2007 Update delayed by NRT/RSS issues Released Sep 2009 Ice Motion Vectors Jun Entire AMSR-E record provided to C. Fowler as input for update Hope to have update by end of year? TOVS no update Arctic Sea Ice News and Analysis continued to provide data for analyses including dealing with F13/F15/F17 NRT data issues.

12 Plans for Upcoming Year Begin acquiring RSS F17 Tbs Obtain Goddard updates Work with Goddard on intersensor calibration Implement Goddard Bootstrap code Remove NSIDC Bootstrap (nsidc-0002) product Replace with Goddard Preliminary Bootstrap (nsidc-0079) product Update of Sea Ice Motion Vectors Continue to coordinate with research projects on Climate Data Record creation Regular updates of other products as they become available Investigate overhaul of end-to-end processing system to increase efficiency and flexibility, to the extent that resources allow