Forecast Origin Dates
J-SCOPE forecast results for the simulation beginning in April 2018 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. In addition to anomalies which inform us about how this year compares to recent years, we also present raw forecasted concentrations of oxygen in mg/L as it has been brought to our attention that having an idea about the extent of hypoxia is also relevant to decisions made in the region. The units (mg/L) were chosen by stakeholders in the region interested in forecasts of hypoxia.
From the maps, oxygen is forecasted to be near climatology at the beginning of the upwelling season (May - June) but lower than climatology toward the end of the upwelling season (July - August) for shelf waters, which persist for the remainder of the forecast (September - December) for both Washington and Oregon. The relative uncertainty ranges from 10% or less at the beginning of the forecast (May - June) but increases for shelf waters to near 50% for some nearshore areas toward the end of the forecast (September - December).
Forecasted bottom oxygen (mg/l), averaged over three ensemble members for each month (May - September), indicates declines in oxygen concentrations over the course of the forecast for both Washington and Oregon, with hypoxia (O2 < 2 mg/l) becoming shelf-wide in July and continuing through September.
Hypoxia extends upward into the water column as well. The percentage of the water column that is forecasted to experience hypoxia (O2 < 2 mg/l) is a metric for this phenomenon. Early in the upwelling season, hypoxia is forecasted to be uncommon over the entire modeled region (<10%) -mainly isolated to the bottom. However, over the course of the summer, forecasted water column hypoxia increases coast-wide, with particularly high rates forecasted for the Oregon shelf and around Cape Elizabeth in August and September where large areas are forecasted to have up to 30% of the water column experiencing hypoxia.
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 the NH-10 and CE042 moorings in early-mid July, which is a couple of weeks before than the climatological onset of hypoxia. The third mooring, Ćháʔba·, located on the outer Washington coast and does not typically reach hypoxic levels, is forecasted to develop hypoxia sometime between August and November, though the forecast becomes highly uncertain around that time.
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 forecasted average of the ensemble members during the summer upwelling season (May - August). In both Oregon and Washington, with the exception of surface waters, the forecast projects that the oxygen concentration for the upwelling season of 2018 will be lower than the climatology on both the shelf and at deeper depths, with the largest anomalies occurring between the ~20-350 meter depth.
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 forecasted well into August is highly uncertain.