Forecast Origin Dates
J-SCOPE forecast results for the simulation beginning in January of 2020 are shown through a series of figures below. In the first figure, each panel represents ensemble averaged anomalies of two month averages for the region. In the second figure, the panels depict the relative uncertainty from the ensemble for the same time periods.
From the maps, oxygen is forecast to be lower than the climatology from the beginning of the forecast largely on the outer shelf, becoming low coastwide by the beginning of the upwelling season (May - June). Coastal waters in Oregon approach climatology by the end of the upwelling season (July - August) as the anomalies weaken by the end of the upwelling season. The relative uncertainty increases over the course of the upwelling season, with uncertainties over the shelf ranging from ~10-20% at the beginning of the upwelling season (May - June) to approximately 50% for coastal waters off of Oregon by the end of the upwelling season (July - August).
Forecasted bottom oxygen concentrations (mg/l), averaged over three ensemble members for each month of the upwelling season, indicate declines in oxygen concentrations over the course of the forecast for both Washington and Oregon, with hypoxia (O2 < 2 mg/l) prominent over much of the Oregon shelf as early as May and expanding to much of the Washington shelf in July and continuing through September.
Hypoxia extends upward into the water column as well. The percentage of the water column that is forecast to experience hypoxia (O2 < 2 mg/l) is a metric for this phenomenon. Early in the upwelling season, hypoxia is forecast to occupy a small percentage of the water column over the entire modeled region (<10%). In June, shelf waters in Oregon begin to experience more hypoxia (~20%). Over the remainder of the upwelling season, the percentage of the water column that is hypoxic increases coast-wide, with particularly high volumes forecast for the Oregon shelf (up to 50%) in August and September. In the J-SCOPE model region, only waters shallower than the 50 meter isobath in Washington are able to maintain relatively low hypoxic volumes (0-10%) in August and September. This suggests the widespread hypoxia forecast above is limited to the bottom and does not expand much into the water column, except in Oregon.
Time series of bottom oxygen from the Washington coast near one of the Olympic Coast National Marine Sanctuary (OCNMS) moorings at Cape Elizabeth (site CE042), from NH-10 mooring off of Newport, Oregon, and from the Ćháʔba· mooring off of La Push, Washington, are shown for each member of the ensemble. The model forecasts that hypoxia will most likely develop at all three moorings - but more likely at the NH-10 and CE042 moorings in early-mid June, which is about one month before the climatological onset of hypoxia (green). Another time series from the outer Washington shelf, Ćháʔba·, forecasts hypoxia onset in July is uncertain for this location as not all of the ensemble members agree.
Finally, climatological cross-sections from the Newport Line in Oregon (44°N) and the Grays Harbor Line in Washington (47°N) are compared to the forecast average of the ensemble members during the summer upwelling season (May - August). In both Oregon and Washington, the forecast projects that the oxygen concentration for the upwelling season of 2020 will be lower than the climatology on both the shelf and at deeper depths, with the largest anomalies occurring between the surface and ~350 m depth in Oregon, and 400 m depth in Washington.
The emergence of anoxia in the model in late summer is caused by a bias associated with the lack of relaxations in the winds (found to be important in a paper by Adams et al, 2013) in the Climate Forecast System input files as well as a bias in the shortwave radiation (see 2013, Year in Review). The model does have skill in predicting the emergence and severity of hypoxia, while it is biased low for these reasons. Given the difficulty in predicting the fall transition in prior forecasts (see 2013, Year in Review), the forecast for low oxygen levels forecast well into August is highly uncertain.