NOAA's Ocean Climate Change Web Portal

The model simulations are described in detail by Pozo Buil et al. (2021).

Regional Ocean Model:

We used the Regional Ocean Modeling System (ROMS, Shchepetkin and McWilliams 2005; Haidvogel et al. 2008) to investigate the effects of climate change on the Northeast Pacific. ROMS is a terrain-following primitive equation model with a free surface using incompressible and hydrostatic approximations. The version used here has a horizontal grid spacing of 10 km and 42 vertical levels with higher resolution near the surface (Veneziani et al. 2009). The domain extends along the west coast of North America from 30N to 48N, covering the U.S. west coast and northern Baja California. The initial and oceanic boundary forcing for the control simulation over the period 1980 to 2010 is obtained from the Simple Ocean Data Assimilation (SODA v2.1.6; Carton and Giese 2008) and the surface forcing from the ECMWF ERA5 reanalysis (Hersbach et al. 2020) and Cross-calibrated multiplatform winds (CCMP; Atlas et al. 2011). ROMS is coupled to the NEMUCSC biogeochemical model, which is based on NEMURO (Kishi et al. 2007) and is specifically parameterized for the CCS with augmented oxygen and carbon cycling (Fiechter et al. 2018, 2020; Cheresh and Fiechter 2020).

Climate change simulations "Delta Method":

The large-scale climate change forcing is implemented using the "time-varying delta method" where the model changes ("delta") relative to a recent period (1980-2010) are added to the observed climatology from that same recent period. This method removes the mean bias while retaining climate variability and change from the global model, and allows for simulation of the full transient response from 1980 to 2100. The delta values were obtained by subtracting the 1980-2010 model climatology from the full model simulation (1980-2100), which is a combination of a historical run (1980-2005) and a future run under the Representative Concentration Pathway 8.5 (RCP8.5) scenario (2006-2100). The deltas were computed for each calendar month and then interpolated to daily values, which were then added to the observed climatology (i.e., the climatology of the forcing used for the control simulation described above). Projections were performed using forcing from three Earth System Models from the phase 5 of the Coupled Model Intercomparison Project (CMIP5): the GFDL ESM2M, Institute Pierre Simon Laplace (IPSL) CM5A-MR, and the Hadley Center (HC) HadGem2-ES. These three models were chosen in part due to their differences in projected physical and biogeochemical change in the Northeast Pacific; they span the range of projected changes in the CMIP5 ensemble.

References

Atlas, R., Hoffman, R. N., Ardizzone, J., Leidner, S. M., Jusem, J. C., Smith, D. K., et al. (2011). A cross-calibrated, multiplatform ocean surface wind velocity product for meteorological and oceanographic applications. Bull. Am. Meteorol. Soc. 92, 157–174. doi: 10.1175/2010bams2946.1.

Carton, J. A., and B. S. Giese, 2008: A reanalysis of ocean climate using Simple Ocean Data Assimilation (SODA). Mon. Wea. Rev., 136, 2999-3017, doi:https://doi.org/10.1175/2007MWR1978.1.

Cheresh, J., and Fiechter, J. (2020). Physical and biogeochemical drivers of alongshore pH and oxygen variability in the California current system. Geophys. Res. Lett. 47:e2020GL089553. doi: 10.1029/2020gl089553.

Fiechter, J., Edwards, C. A., and Moore, A. M. (2018). Wind, circulation, and topographic effects on alongshore phytoplankton variability in the California current. Geophys. Res. Lett. 45, 3238–3245. doi: 10.1002/2017gl076839.

Fiechter, J., Santora, J. A., Chavez, F., Northcott, D., and Messié, M. (2020). Krill hotspot formation and phenology in the california current ecosystem. Geophys. Res. Lett. 47:e2020GL088039. doi: 10.1029/2020gl088039.

Haidvogel, D. B., Arango, H., Budgell, W. P., Cornuelle, B. D., Curchitser, E., Di Lorenzo, E., et al. (2008). Ocean forecasting in terrain-following coordinates: formulation and skill assessment of the Regional Ocean modeling system. J. Comput. Phys. 227, 3595–3624. doi: 10.1016/j.jcp.2007.06.016.

Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz-Sabater, J., et al. (2020). The ERA5 global reanalysis. Q. J. R. Meteorol. Soc. 146, 1999–2049. doi: 10.1002/qj.3803.

Kishi, M. J., Kashiwai, M., Ware, D. M., Megrey, B. A., Eslinger, D. L., Werner, F. E., et al. (2007). NEMURO—a lower trophic level model for the North Pacific marine ecosystem. Ecol. Model. 202, 12–25. doi: 10.1016/j.ecolmodel.2006.08.021.

Pozo Buil, M., Jacox, M. G., Fiechter, J., Alexander, M. A., Bograd, S. J., Curchitser, E. N., Edwards, C. A., Rykaczewski, R. R. and Stock, C. A. (2021) A Dynamically Downscaled Ensemble of Future Projections for the California Current System. Front. Mar. Sci. 8:612874. doi: 10.3389/fmars.2021.612874

Shchepetkin, A. F., and J. C. McWilliams, 2005: The Regional Oceanic Modeling System (ROMS): A split-explicit, free-surface, topography-following-coordinate oceanic model, Ocean Modell., 9, 347-404.

Veneziani, M., Edwards, C. A., Doyle, J. D., and Foley, D. (2009). A central California coastal ocean modeling study: 1. Forward model and the influence of realistic versus climatological forcing. J. Geophys. Res. 114:4774. doi: 10.1029/2008jc004774.

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