Assessing the skill of the improved treatment of riverine freshwater in the Community Earth System Model relative to a new salinity climatology
Climate | Fresh Water Studies | Oceanography
Recent studies have explored the sensitivity of global ocean model simulations to the treatment of riverine freshwater and the representation of estuarine processes via an estuary box model (EBM) applied within CESM. This study builds on these efforts by assessing the model skill score relative to a new salinity climatology. The new climatology averages the original observational data of the World Ocean Database directly onto the CESM ocean-component tracer-grid cells without spatial interpolation, smoothing, or other gap-filling techniques to mitigate coastal ocean salinity bias present in the World Ocean Atlas. The mean squared error (MSE) for coastal upper ocean salinity relative to climatology is reduced by up to 14%, and the MSE of near surface salinity stratification is reduced by up to 28% near major river mouths in the simulations with improved treatments of river runoff. The improvement in upper ocean bulk salinity is attributed primarily to focusing runoff as point sources thereby avoiding the artificial horizontal spreading of the control run and to applying a locally-varying instead of a global constant reference salinity for riverine virtual salt fluxes. The improvements in near-surface salinity stratification are primarily attributed to adding parameterized estuarine mixing with the EBM. Salinity and salinity stratification skill improvements are achieved not just near large rivers, but also along the global coast and skill improvements extend far offshore. Despite these improvements, many other sources of model-climatology mismatch in coastal salinity and stratification remain and merit further attention.
Sun, Qiang; Whitney, Michael M.; Bryan, Frank O.; and Tseng, Yu-Heng, "Assessing the skill of the improved treatment of riverine freshwater in the Community Earth System Model relative to a new salinity climatology" (2019). Department of Marine Sciences. 6.
WOD2POP climatology for salinity and temperature
CESM_code.zip (538172 kB)
CESM model documents, source code and script
CESM_salt_result_31yr_60ry_avg.mat (1350180 kB)
CESM model results for salinity
CESM_temp_result_31yr_60ry_avg.mat (1460559 kB)
CESM model results for temperature
Figures_matlab.zip (54289 kB)
Analysis result of figures
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