Co-Investigator (Co-PI): David Long, Brigham Young University
One of the goals of the NASA Earth Science Enterprise Research Strategy is to develop datasets that advance our understanding of the cryosphere and its relationship with the rest of the Earth System on time scales of seasons to a few years (NASA, 2000). Variations in sea ice extent, terrestrial snow and vegetation cover, upper ocean circulation, and atmospheric circulation are mutually interactive and generate significant variations of climate on seasonal to interannual time scales, both globally and in specific regions. Our proposal addresses climate variability by continued production and enhancement of Level 3 gridded passive microwave data sets valuable in understanding the dynamics of the cryosphere and terrestrial ecosystems, together with interactions with the global climate and the hydrologic cycle, over a variety of seasonal, interannual and multi-decadal time scales.
Polar snow and ice-covered ocean and land surfaces are especially sensitive to climate change and are observed to fluctuate on interannual to decadal timescales. Due to limited sunlight and meteorological sensitivity, microwave data is particularly useful for measuring this variability and to address the specific role that snow and ice play in both influencing and responding to the long-term state of the oceans and atmosphere. Passive microwave radiometers have been a mainstay of remote sensing of the cryosphere, despite being available at relatively low resolutions (~25 km) compared to optical techniques (less than 1 km). They provide short-timescale, large-area spatial coverage, and high temporal repeat observations, for monitoring hemispheric-wide changes.
Most users of radiometer data prefer to use gridded Level 3 data for cryosphere studies. 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 grids that are not easily accommodated in modern software packages. Further, since the time that the first Level 3 data sets were developed, the Level 2 passive microwave data on which they are based have been reprocessed as Fundamental CDRs (FCDRs) with improved calibration statistics. There is now a great need to regenerate gridded Level 3 products using improved techniques from these modern Level 2 FCDRs.
Using validated, state-of-the-art interpolation methods, we propose a complete reprocessing using the most mature available Level 2 satellite passive microwave records from 1978 to the present. We will reprocess the complete data record from Scanning Multichannel Microwave Radiometer (SMMR), Special Sensor Microwave Imager/Sounder (SSM/I-SSMIS) and Advanced Microwave Scanning Radiometer—EOS (AMSR-E) in a single, enhanced-resolution gridded passive microwave ESDR. The ESDR will make use of the latest improvements to the Level 2 SSM/I-SSMIS and AMSR-E data record that are newly available this year. The new, gridded ESDR will satisfy the needs of current and future users who require a reliable, consistent, gridded time series of microwave radiometer data.