NSIDC DAAC UWG Meeting August 9-10 Boulder, CO Developing An Extended Global Data Record on Daily Landscape Freeze-Thaw Status from Satellite Passive Microwave Remote Sensing John Kimball, Youngwook Kim, Joe Glassy, Jinyang Du NTSG, University of Montana NSIDC DAAC UWG Meeting August 9-10 Boulder, CO

Processing Overview Science study area: All global land areas affected by seasonal freezing and thawing. Types of data used: 37 GHz V-pol daily Tb retrievals; AM & PM orbit; swath and 25-km global (EASE v1) grids Nimbus-7 SMMR Pathfinder (http://nsidc.org/data/nsidc-0071.html), SSM/I-SSMIS Pathfinder (http://nsidc.org/data/nsidc-0032.html), AMSR-E (http://nsidc.org/data/nsidc-0301.html) AMSR2 (https://gcom-w1.jaxa.jp)

Processing Overview Cont. Overview of processing steps Calibration of overlapping 37 GHz, V-pol Tb records from SMMR and SSM/I Calibration of AMSR-E/2 36.5 GHz, V-pol Tb records using similar overlapping FY-3B MWRI Tb retrievals. Per grid cell Modified Seasonal Threshold Algorithm (MSTA) Tb temporal change classification Per grid cell annual MSTA calibration of Tb freeze-thaw threshold using ERA-Interim daily surface air temperature Application of calibrated MSTA using daily AM and PM Tb inputs to classify FT status. FT global accuracy assessment using collocated in-situ WMO daily temperatures Production of annual QA maps and per grid cell daily QC flags Production of final product formats (HDF5, GeoTIFF, Binary) Challenges Lack of EASE-grid version 2 (V2) format SSMR, SSM/I and AMSR-E/2 daily Tb records Large file sizes and data processing loads required to process global Tb orbital swath data For production of finer resolution FT retrievals closer to native (~12-km) 37-GHz Tb footprint rather than standard 25-km gridding. Recommendations Provide SMMR, SSM/I and AMSR Tb records in EASE v2 format

Scope of Research Science question(s) addressed: Can similar 37 GHz Tb retrievals from different satellite microwave sensors be used to quantify consistent patterns and trends in landscape FT status? What are the impacts of varying land cover, terrain and algorithm assumptions on the FT accuracy? Does the research cross scientific domains? Yes: global change, cryosphere, hydrology, ecosystems Local (or Regional) versus global extent? Global and polar regional Long time series? 1979 – present enabled from similar overlapping satellite records and continuing operations for key sensors (SSM/I, AMSR2) Is data latency/download time critical? Not critical for research, but would be optimal to have at least annual updates. Potential exists for similar FT retrievals at shorter latencies through LANCE for other operational applications

Types of data being used Primary observational data used SMMR, SSM/I(S), AMSR-E/2 daily (AM/PM) Tb MODIS (MOD11C1) 8-day LST (used for Cal/Val) ERA-Interim reanalysis (used for calibration) WMO Summary of the Day (used for validation) Data types & formats needed/desired Primarily passive microwave; visible imagery used for calibration and secondary validation assessments Global and Polar EASE-grid v2 desired, but still working with v1 format consistent with input Tb data Combining data with other sources or models? Modified seasonal threshold algorithm (MSTA) for Tb temporal change-based FT classification, where grid cell-wise Tb FT thresholds calibrated annually using ERA-Interim daily surface temperatures. Data volumes ~8 GB and 31 GB for final FT-ESDR in hdf5 and binary formats Much Larger data volumes involved in data processing

Data Workflow Driven by research objectives & periodic requests from community for FT-ESDR updates Periodic data pull to local server for processing, with periodic revisits to NSIDC for updating Tb records Challenges: Processing and formatting of AMSR Tb orbital swath data Large AMSR L2a swath data volumes Lack of standardized EASE-grid V2 format for gridded Tb products Maintaining FT-ESDR results in multiple formats (HDF5, GeoTIFF, Binary) due to variable user needs.

Recommendations Improvements to DAAC tools/services NSIDC Tb data posting to EASE-grid V2 format Enhanced services for provision of data records in a variety of common formats Shared software tools for viewing/translating/reformatting datasets