Abstract. The potential for multiyear prediction of impactful Earth
system change remains relatively underexplored compared to shorter
(subseasonal to seasonal) and longer (decadal) timescales. In this study, we
introduce a new initialized prediction system using the Community Earth
System Model version 2 (CESM2) that is specifically designed to probe
potential and actual prediction skill at lead times ranging from 1 month out
to 2 years. The Seasonal-to-Multiyear Large Ensemble (SMYLE) consists of a
collection of 2-year-long hindcast simulations, with four initializations per
year from 1970 to 2019 and an ensemble size of 20. A full suite of output is
available for exploring near-term predictability of all Earth system
components represented in CESM2. We show that SMYLE skill for El
Niño–Southern Oscillation is competitive with other prominent seasonal
prediction systems, with correlations exceeding 0.5 beyond a lead time of 12
months. A broad overview of prediction skill reveals varying degrees of
potential for useful multiyear predictions of seasonal anomalies in the
atmosphere, ocean, land, and sea ice. The SMYLE dataset, experimental
design, model, initial conditions, and associated analysis tools are all
publicly available, providing a foundation for research on multiyear
prediction of environmental change by the wider community.
The Blob was the early manifestation of the Northeast Pacific marine heat wave from 2013 to 2016. While the upper ocean temperature in the Blob has been well described, the impacts on marine biogeochemistry have not been fully studied. Here, we characterize and develop understanding of Eastern North Pacific upper ocean biogeochemical properties during the Winter of 2013–2014 using in situ observations, an observation‐based product, and reconstructions from a collection of ocean models. We find that the Blob is associated with significant upper ocean biogeochemical anomalies: A 5% increase in aragonite saturation state (temporary reprieve of ocean acidification) and a 3% decrease in oxygen concentration (enhanced deoxygenation). Anomalous advection and mixing drive the aragonite saturation anomaly, while anomalous heating and air‐sea gas exchange drive the oxygen anomaly. Marine heatwaves do not necessarily serve as an analog for future change as they may enhance or mitigate long‐term trends.
Abstract. The potential for multiyear prediction of impactful Earth system change remains relatively underexplored compared to shorter (subseasonal to seasonal) and longer (decadal) timescales. In this study, we introduce a new initialized prediction system using the Community Earth System Model Version 2 (CESM2) that is specifically designed to probe potential and actual prediction skill at lead times ranging from 1 month out to 2 years. The Seasonal-to-Multiyear Large Ensemble (SMYLE) consists of 2-year long hindcast simulations that cover the period from 1970 to 2019, with 4 initializations per year and an ensemble size of 20. A full suite of output is available for exploring near-term predictability of all Earth system components represented in CESM2. We show that SMYLE skill for El Niño-Southern Oscillation is competitive with other prominent seasonal prediction systems, with correlations exceeding 0.5 beyond a lead time of 12 months. A broad overview of prediction skill reveals varying degrees of potential for useful multiyear predictions of seasonal anomalies in the atmosphere, ocean, land, and sea ice. The SMYLE dataset, experimental design, model, initial conditions, and associated analysis tools are all publicly available, providing a foundation for research on multiyear prediction of environmental change by the wider community.
Anthropogenic carbon emissions and associated climate change are driving
rapid warming, acidification, and deoxygenation in the ocean, which
increasingly stress marine ecosystems. On top of long-term trends, short
term variability of marine stressors can have major implications for
marine ecosystems and their management. As such, there is a growing need
for predictions of marine ecosystems on monthly, seasonal, and
multi-month timescales. Previous studies have demonstrated the ability
to make reliable predictions of the surface ocean physical and
biogeochemical state months to years in advance, but few studies have
investigated forecasts of multiple stressors simultaneously or assessed
the forecast skill below the surface. Here, we use the Community Earth
System Model (CESM) Seasonal to Multiyear Large Ensemble (SMYLE) along
with novel observation-based biogeochemical and physical products to
quantify the predictive skill of dissolved inorganic carbon, dissolved
oxygen, and temperature in the surface and subsurface ocean. CESM SMYLE
demonstrates high physical and biogeochemical predictive skill multiple
months in advance in key oceanic regions and frequently outperforms
persistence forecasts. We find up to 10 months of skillful forecasts,
with particularly high skill in the Northeast Pacific (Gulf of Alaska
and California Current Large Marine Ecosystems) for temperature, surface
DIC, and subsurface oxygen. Our findings suggest that dynamical marine
ecosystem prediction could support actionable advice for decision
making.
Anthropogenic climate change is leading to simultaneous warming, deoxygenation, and acidification stress on marine ecosystems (Bopp et al., 2013;Doney et al., 2009;Kwiatkowski et al., 2020). The North Pacific Ocean is particularly vulnerable to the effects of ocean acidification and deoxygenation, owing to the naturally high concentrations of dissolved inorganic carbon (DIC) and naturally low oxygen concentrations that occur here (Keeling et al., 2010;Levin, 2018;Ono et al., 2019). On top of these long-term changes in ocean state are shortterm extreme events defined by rapid disruptions such as marine heatwaves, which also likely have biogeochemical signatures (Bopp et al., 2013;Frölicher & Laufkötter, 2018). The North Pacific is thus especially threatened by these ecosystem multi-stressor or compound extreme events.A strong marine heatwave known as "the Blob" appeared in the open Gulf of Alaska (GOA) in the winter of 2013-2014, driven by an anomalous high pressure ridge (Bif et al., 2019;Bond et al., 2015;
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