Cryospheric and Polar Processes Seminar
A new era for NSIDC's gridded passive microwave data: Using image reconstruction to enhance spatial resolution of the satellite passive microwave historical record
by Mary Jo Brodzik
Currently available global gridded passive microwave data sets serve a diverse community of hundreds of data users, but do not meet many requirements of modern ESDRs or CDRs, most notably in the areas of intersensor calibration and consistent processing methods. The original gridding techniques were relatively primitive and were produced on 25 km grids using the original EASE-Grid definition that is not easily accommodated in modern software packages. Further, since the first Level 3 data sets were produced, the Level 2 passive microwave data on which they were based have been reprocessed as Fundamental CDRs (FCDRs) with improved calibration and documentation. We are funded by NASA MEaSUREs to reprocess the historical gridded data sets as EASE-Grid 2.0 Earth System Data Records (ESDRs), using the most mature available Level 2 satellite passive microwave (SMMR, SSM/I-SSMIS, AMSR-E) records from 1978 to the present. We have worked with our Early Adopter user community, who have reviewed and provided feedback on 18 months of prototype data from SSM/I and AMSR-E. The prototype data set includes grids derived from the two candidate image reconstruction techniques we have compared: 1) Backus-Gilbert (BG) interpolation and 2) a radiometer version of Scatterometer Image Reconstruction (rSIR).
For our final processing, we are producing coarse-resolution (25 km) averaged TB grids, and enhanced-resolution rSIR grids at resolutions up to 3 km (actual resolution enhancement depends on channel). Data are gridded to the EASE-Grid 2.0 definition and formatted as netCDF-CF files, which allows users to extract compliant geotiff images, and provides for easy importing and correct reprojection interoperability in many standard packages, including IDL, ENVI, gdal, Panoply and Arc* tools. As a consistently-processed, high-quality satellite passive microwave ESDR, we expect this data set to supercede at least 4 of NSIDC's standard EASE-Grid passive microwave products: the SSM/I-SSMIS EASE-Grid TB products (nsidc-0032), the enhanced-resolution SSM/I and AMSR-E data (nsidc-0464), the SMMR Pathfinder (nsidc-0071) and AMSR-E gridded TB products (nsidc-0301).