Forecast Origin Dates
J-SCOPE forecast results for the simulation beginning in April of 2021 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 on the shelf is forecast to be lower than the climatology during the upwelling season of 2021 in Washington and Oregon. The relative uncertainty is low (<20%) for the first half of the upwelling season (May - June) but increases on the shelf (up to ~50%) during the second half of the upwelling season (July - August) and remains high in the fall.
Forecast bottom oxygen (mg/l), averaged over three ensemble members for each month, indicates declines in oxygen concentrations over the course of the forecast for both Washington and Oregon, with hypoxia (O2 < 2 mg/l) with hypoxia prominent from the shelf break to the 100 meter isobath off of the Oregon coast in May and extending over much of the Oregon coast by June. On the Washington coast, patches occur in June on the shelf and by July most of the shelf is covered with the exception of a small region north of Ćháʔba· remaining normoxic until August. These hypoxic conditions persist on the continental shelf through September when the northernmost region of the Washington shelf becomes hypoxic too.
Over the course of the upwelling season, 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. By combining this forecast with the forecast for bottom hypoxia (above), we can get an idea of how extensive hypoxia may be in the three-dimensional ocean habitat. Early in the upwelling season (May - June), hypoxia is forecast for the Oregon shelf waters, mainly near Heceta Bank where up to 20% of the water column may be hypoxic. In July, hypoxia is forecast to intensify near Heceta Bank (<40%) and begins to occur at low volumes throughout much of the Oregon and Washington shelf (<20%). By late summer (August and September), the percentage of the water column that is hypoxic increases coast-wide, with particularly high hypoxic volumes forecast on the Oregon shelf (~50%) and moderate hypoxic volumes found deeper than the ~50m isobath in Washington (<40%). All together, these figures suggest that the widespread hypoxia forecast above is limited to near bottom habitats for the majority of the Washington coast during the upwelling season while hypoxia expansion into the water column is more extensive 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 is highly likely to develop at all three moorings. At the OCNMS mooring (CE042), all three ensemble members agree that hypoxia will develop earlier than the climatology, likely in June. For the NH-10 mooring, again all three ensemble members forecast hypoxia will occur earlier than climatology, likely beginning in June. Another time series from the outer Washington shelf, Ćháʔba·, forecasts hypoxia will occur later in the upwelling season (July - August) but this is highly uncertain for this location given the wide spread in the ensemble members.
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 2021 will be lower than the climatology on both the shelf and at deeper depths, with the largest anomalies occurring between the surface and ~250 m depth in both Oregon and Washington, but anomalies extend much deeper than that in both sections.
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.