Evaluation of MODIS and VIIRS Cloud-Gap Filled Snow-Cover Products for Production of a Moderate-Resolution Earth Science Data Record

Cloud cover frequently creates gaps in snow-cover maps that are generated from the MODerate-resolution Imaging Spectroradiometer (MODIS) on both the Terra and Aqua satellites, and from the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi - National Polar Partnership (S-NPP) satellite. To address the need for a cloud-free daily snow-cover extent (SCE) product for both MODIS and VIIRS, a gap-filling algorithm was developed for MODIS Collection 6.1 and VIIRS Collection 2 processing (Riggs et al., 2018). Early results show that the Terra MODIS CGF maps are more accurate than are the Aqua MODIS CGF maps (Hall et al., 2019). It is thus anticipated that the Terra MODIS and S-NPP cloud-gap filled (CGF) SCE maps will be useful as the basis for a moderate-resolution Earth Science Data Record (ESDR) of SCE. To evaluate the consistency of a potential ESDR, comparisons of daily Terra MODIS and S-NPP VIIRS CGF SCE products have been undertaken. A comparison was conducted for a 3-month time period in 2012 for a large study area in the western U.S. (2,487,610 km²). Though the MODIS and VIIRS daily GCF SCE maps show excellent correspondence, the VIIRS maps, on average, show 11,070 km² more snow as compared to the MODIS products on a given day which is ~0.45 percent of the study area. A moderate-resolution ESDR is anticipated to extend the SCE data record from the Terra MODIS that began in 2000, into the VIIRS era, beginning in 2011, through the early 2030s and perhaps beyond. A thorough analysis of the uncertainties of these products globally will be possible only after the entire time series of both MODIS and VIIRS have been processed and archived which is likely to occur sometime in 2020.

References

Hall, D. K., Riggs, G. A., DiGirolamo, N. E., and Román, M. O., 2019 (in review): MODIS Cloud-Gap Filled Snow-Cover Products: Advantages and Uncertainties, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2019-123.

Riggs, G.A., Hall, D.K., and Román, M.O., 2017: Overview of NASA's MODIS and Visible Infrared Imaging Radiometer Suite (VIIRS) snow-cover, Earth Syst. Sci. Data, 9:1-13, https://www.earth-syst-sci-data.net/9/765/2017/.