Errors
; Snow melting systems
; Stochastic models
; Stochastic systems
; Assimilation system
; Data assimilation
; Data assimilation systems
; Evolution characteristics
; Land data assimilation
; Snow accumulation
; Stochastic perturbations
; Uncertainty inputs
; Snow
; accuracy assessment
; data assimilation
; data set
; depth
; error analysis
; headwater
; model test
; model validation
; snow
; snow accumulation
; snowmelt
; uncertainty analysis
; Colorado Basin [North America]
; Great Lakes [North America]
英文摘要:
Accurate specification of the model error covariances in data assimilation systems is a challenging issue. Ensemble land data assimilation methods rely on stochastic perturbations of input forcing and model prognostic fields for developing representations of input model error covariances. This article examines the limitations of using a single forcing dataset for specifying forcing uncertainty inputs for assimilating snow depth retrievals. Using an idealized data assimilation experiment, the article demonstrates that the use of hybrid forcing input strategies (either through the use of an ensemble of forcing products or through the added use of the forcing climatology) provide a better characterization of the background model error, which leads to improved data assimilation results, especially during the snow accumulation and melt-time periods. The use of hybrid forcing ensembles is then employed for assimilating snow depth retrievals from the AMSR2 instrument over two domains in the continental USA with different snow evolution characteristics. Over a region near the Great Lakes, where the snow evolution tends to be ephemeral, the use of hybrid forcing ensembles provides significant improvements relative to the use of a single forcing dataset. Over the Colorado headwaters characterized by large snow accumulation, the impact of using the forcing ensemble is less prominent and is largely limited to the snow transition time periods. The results of the article demonstrate that improving the background model error through the use of a forcing ensemble enables the assimilation system to better incorporate the observational information.
Hydrological Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, United States; I.M. Systems Group Inc., Environmental Modeling Center, NOAA NCEP, College Park, MD, United States; Hydrosphere, Biosphere and Geophysics, Earth Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, United States; Science Applications International Corporation, McLean, VA, United States; Research to Operations, Met Office, Exeter, United Kingdom
Recommended Citation:
Kumar S,V,, Dong J,et al. Role of forcing uncertainty and background model error characterization in snow data assimilation[J]. Hydrology and Earth System Sciences,2017-01-01,21(6)