Calibrated, Enhanced-Resolution Daily EASE-Grid 2.0 Passive Microwave Brightness Temperatures (CETB) montage of cylindrical and Northern and Southern Hemisphere azimuthal projections.
Collected from passive microwave sensors observing the Earth since 1978, brightness temperatures are used to study many important geophysical variables, including the dramatic recent decline in sea ice concentrations. The Calibrated, Enhanced-Resolution Brightness Temperatures (CETB) data sets (Brodzik et al., 2016; 2019) provide gridded passive microwave images at conventional and enhanced spatial resolutions up to 3.125 km, now with daily, near real-time updates for currently operating SSMIS and SMAP observations.
Adhering to FAIR (Findable, Accessible, Interoperable and Reusable) Data Principles (Wilkinson et al., 2016), the CETB data comprise over 60 TB and more than 4 million files. Using FAIR principles improves the ability of humans and our machines to find and understand the data we produce, and to trust in the science derived from this ongoing climate record.
EASE-Grid 2.0 AMSR-E 36 GHz vertically-polarized, evening pass brightness temperatures, 31 Mar 2011. Images showing conventional, coarse resolution data at 25 km (left) and enhanced-resolution data at 3.125 km (right). GSHSS coastlines in green (Wessel and Smith, 2015).
Originally funded by NASA MEaSUREs, our project reprocessed the long record of satellite passive microwave gridded brightness temperatures:
- With the latest Level 2 cross-sensor calibrations (Berg et al., 2018) in EASE-Grid 2.0 projections (Brodzik et al., 2012; 2014)
- Using image reconstruction to enhance spatial resolutions (Long and Brodzik, 2016)
- As a high quality Earth System Data Record (Brodzik et al., 2018)
With additional funding from NASA, NOAA and the Department of Defense, we have extended processing to include SMAP; we now produce daily, near real-time SSMIS and SMAP images. We will be including AMSR2 CETB images in early 2022.
AMSR-E 36 GHz horizontally-polarized CETB conventional-resolution, low-noise, 25 km GRD (center) vs. enhanced-resolution, 3.125 km rSIR (right) near Vancouver Island, North America, 20 Feb 2003, with elevation from SRTM DEM (left). GSHSS coastlines in green (Wessel and Smith, 2015). Note that rSIR image reconstruction is resolving elevation-related variability.
The radiometer version of Scatterometer Image Reconstruction (rSIR) transforms radiometer data from swath to gridded format (Long and Brodzik, 2016). Using rSIR, we produce the EASE-Grid 2.0 CETB product at enhanced resolutions up to 3.125 km in addition to conventional, low-noise, low-resolution gridded images (denoted GRD) at 25 km. For GRD and rSIR images, the effective gridded image resolution depends on the number of input measurements for each pixel and the precise details of measurement overlap, orientation and spatial location.
Gridding techniques with the lowest noise factors take the average of all measurements whose locations fall inside the gridded pixel area, producing smooth but relatively coarse-resolution output (left). Compare to image reconstruction for resolution enhancement (right), which takes advantage of oversampled information in the overlapping brightness temperatures footprints to deduce higher-resolution gridded images.
In this poster, we discuss methods to estimate the effective resolution enhancement of CETB data. We include selected cryospheric applications of the enhanced-resolution data: to map the extent of ice sheet firn aquifers and to estimate melt onset timing. To demonstrate CETB data interoperability, we include a movie of CETB data, comparing conventional spatial resolution with the enhanced-resolution improvements now possible.