PoDAG XXIV: MODIS Snow Albedo Prototype Proposal

1. PoDAG XXIV: MODIS Snow Albedo Prototype Proposal Marilyn Kaminski MODIS Product Team Lead November 3, 2005

2. Status of MODIS Snow Albedo Product • Currently produced as a data array in MODIS daily snow products, Version 4 • Limited time series available: 9/14/03 – present • Algorithm has known problems with mountainous terrain but is better on level surface (see next slides) • Validation status: beta, with no funding for validation available to science team Why not continue as is? NASA is reluctant to continue production of unvalidated data sets, so snow albedo is being removed from production when Version 5 begins processing Spring ‘06 PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

3. Example: Mountainous Terrain Afghanistan: February 16, 2005 MOD09 Surface Reflectance MOD10A1 Snow Albedo PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

4. MOD09 Surface Reflectance Example: Mountainous Terrain Afghanistan: February 16, 2005 N N Ridgeline Ridgeline MOD10A1 Snow Albedo • Problems: • Albedo can’t be 100% • Albedo on north facing slopes should be >= albedo on south facing slopes PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

5. Continued Need for Snow Albedo Product • Researchers have ongoing needs for a daily snow albedo measurement • Another MODIS product includes global surface albedo • Produced at 16-day frequency - inadequate for snow applications • Algorithm not specific to snow Side note: Sea ice albedo being developed by science team; not part of current discussion PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

6. NSIDC Proposal for Snow Albedo Prototype • NSIDC is writing a white paper detailing ideas to produce an equivalent prototype data set • Regional in scope to provide an opportunity to validate the product with existing independent efforts augmented by in-house resources • Small-scale to minimize computational and network requirements before product utility is established • Based on existing MOD10A1 algorithm, with code changes to be analyzed • Data to be produced at NSIDC or MODAPS and distributed to users • Funding TBD, with potential sources identified PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

7. Scope of Proposed Prototype • Regional focus: Greenland and Afghanistan • Known user need • Existing validation efforts • Small scale minimizes computational and network requirements • Topographical variation • Analysis of code to look for easily-identifiable problems while defining an approach for more extensive rework • Study of existing validation efforts to determine areas of need • Identify additional areas of user need (may not need global production in long term) PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

8. Data Requirements for Prototype • Existing algorithm runs at MODIS processing facility with all inputs readily available • All required inputs can be obtained from GDAAC via subscription, with exception of MOD10L2G (only available for a few days at MODAPS web site) • Code has been modified to substitute MOD10A1 for MOD10L2G with minimal impact to result PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

9. Processing Requirements for Prototype • Easiest (least expensive) production path is continuation of existing scenario: production at MODAPS with result sent to NSIDC (requires waiver by NASA to continue production of unvalidated data set, and re-introduction of code) • Alternative 1: ingest data by subscription, process outside ECS, and archive/distribute within ECS (similar to NISE production) • Alternative 2: ingest data by subscription, process outside ECS, and archive/distribute outside ECS PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

10. Expected Outcome • Determination of optimal processing path for long-term production; analysis of resource requirements • Minor code changes to existing code and identification of major changes; analysis of resource requirements • Identification of additional validation needs to produce a robust data set • Identification of additional geographic regions of interest to satisfy immediate user needs PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005

11. Next Steps • Need go-ahead from PoDAG to finish white paper and seek funding for prototype effort • Analyze existing code and look for easily-resolvable problems • Analyze processing options to find best path for prototype processing PoDAG XXIV Marilyn Kaminski, MODIS Product Team Lead November 3, 2005