The future regional sea level (RSL) rise in the western North Pacific is investigated by dynamical downscaling with the Regional Ocean Modeling System (ROMS) with an eddy-permitting resolution based ...on three global climate models—MIROC-ESM, CSIRO-Mk3.6.0, and GFDL-CM3—under the highest greenhouse-gas emission scenario. The historical run is forced by the air-sea fluxes calculated from Coordinated Ocean Reference Experiment version 2 (COREv2) data. Three future runs—ROMS-MIROC, ROMS-CSIRO, and ROMS-GFDL—are forced with an atmospheric field constructed by adding the difference between the climate model parameters for the twenty-first and twentieth century to fields in the historical run. In all downscaling, the RSL rise along the eastern coast of Japan is generally half or less of the RSL rise maxima off the eastern coast. The projected regional (total) sea level rises along the Honshu coast during 2081–2100 relative to 1981–2000 are 19–25 (98–104), 6–15 (71–80), and 8–14 (80–86) cm in ROMS-MIROC, ROMS-CSIRO, and ROMS-GFDL, respectively. The discrepancies of the RSL rise along the Honshu coast between the climate models and downscaling are less than 10 cm. The RSL changes in the Kuroshio Extension (KE) region in all downscaling simulations are related to the changes of KE (northward shift or intensification) with climate change.
In order to understand how North Pacific (NP) marine ecosystems have varied, 120 marine biological time series for both the western (29 time series) and eastern (91 time series) NP were analyzed with ...a Principal Component Analysis (PCA) for the period 1965–2006. This is the first attempt to conduct a multivariate analysis for a large number of marine biological data in the western and eastern NP combined. We used Monte-Carlo simulation to evaluate confidence levels of correlations and explained variance ratio of PCA modes while accounting for auto-correlation within the analyzed time series. All first mode principal components (PC1s), which are the time coefficients of the first PCA modes, calculated for the data in the whole, western, and eastern NP exhibit a long-term trend. The PC1s were associated with an overall increase of Alaskan and Japanese/Russian salmon, and decreases of groundfish across the basin. This mode was closely related to the warming of sea-surface temperature over the NP and over the global oceans, thereby suggesting that the strongest mode of the NP marine ecosystem was already influenced by global warming. The eastern NP PC2, characterized by multi-decadal variability, was correlated positively with salmon and negatively with groundfish. On the other hand, the western NP PC2 exhibited slightly shorter timescale interdecadal variability than the eastern NP PC2 and was negatively correlated with zooplankton and two small pelagic fish time series around Japan. The eastern NP PC2 was most strongly related to the Pacific (inter-)Decadal Oscillation index, while the western NP PC2 was most closely related to the North Pacific Gyre Oscillation index. Consequently, the present analysis provides a new and unified view of climate change and marine ecosystem variations across the western and eastern NP. In particular, it is suggested that global warming has already substantially influenced the NP marine ecosystem, and that groundfish may suffer more than pelagic fish in response to future global warming.
This perspective paper discusses how the research community can promote enhancement of marine ecosystem forecasts using physical ocean conditions predicted by global climate models (GCMs). We review ...the major climate prediction projects and outline new research opportunities to achieve skillful marine biological forecasts. Physical ocean conditions are operationally predicted for subseasonal to seasonal timescales, and multi-year predictions have been enhanced recently. However, forecasting applications are currently limited by the availability of oceanic data; most subseasonal-to-seasonal prediction projects make only sea-surface temperature (SST) publicly available, though other variables useful for biological forecasts are also calculated in GCMs. To resolve the bottleneck of data availability, we recommend that climate prediction centers increase the range of ocean data available to the public, perhaps starting with an expanded suite of 2-dimensional variables, whose storage requirements are much smaller than 3-dimensional variables. Allowing forecast output to be downloaded for a selected region, rather than the whole globe, would also facilitate uptake. We highlight new research opportunities in both physical forecasting (e.g., new approaches to dynamical and statistical downscaling) and biological forecasting (e.g., conducting biological reforecasting experiments) and offer lessons learned to help guide their development. In order to accelerate this research area, we also suggest establishing case studies (i.e., particular climate and biological events as prediction targets) to improve coordination. Advancing our capacity for marine biological forecasting is crucial for the success of the UN Decade of Ocean Science, for which one of seven desired outcomes is “A Predicted Ocean”.
A major challenge for managing impacts and implementing effective mitigation and adaptation strategies for coastal zones affected by future sea level (SL) rise is our very limited capacity to predict ...SL change on coastal scales, over various timescales. Predicting coastal SL requires the ability to monitor and simulate a multitude of physical processes affecting SL, from local effects of wind waves and river runoff to remote influences of the large-scale ocean circulation on the coast. Here we assess our current understanding of the causes of coastal SL variability on seasonal to multi-decadal timescales, including geodetic, oceanographic and atmospheric aspects of the problem, and review available observing systems informing on coastal SL. We also review the ability of current models and data assimilation systems to estimate coastal SL variations and of atmosphere-ocean global coupled models and related regional downscaling efforts to project future SL changes. We discuss (1) key observational gaps and uncertainties, and priorities for the development of an optimal and integrated coastal SL observing system, (2) strategies for advancing model capabilities in forecasting short-term processes and projecting long-term changes affecting coastal SL, and (3) possible future developments of sea level services enabling better connection of scientists and user communities and facilitating assessment and decision making for adaptation to future coastal SL change.
A high‐resolution transect of atmospheric soundings across the Kuroshio Current in the East China Sea was conducted onboard a ship in June 2012 with the objective of analyzing the influence of the ...complex sea surface temperature (SST) distribution on the Baiu frontal zone (BFZ). Expendable bathythermograph castings and continuous surface meteorological observations were also examined. Two distinct mesoscale atmospheric fronts, characterized by changes of wind direction in the lower troposphere and surface air temperature, were found in the BFZ. One (northern) atmospheric front was observed around the SST front in relation to a warm water tongue extending from the Kuroshio. A high SST region around the northern atmospheric front enhances unstable near surface stratification and intensifies turbulent heat flux. They help modify the marine atmospheric boundary layer in the BFZ. The other (southern) atmospheric front was at the southern end of the BFZ. Intense evaporation over the Kuroshio and moisture transport by southerly winds were important in forming the conditionally unstable air masses in the lower troposphere of the BFZ.
Key Points
High‐resolution field campaign was conducted in the East China Sea
Small‐scale sea surface temperature variations influence Baiu frontal zone
Evaporation from Kuroshio has a remote impact on Baiu frontal zone
Upper ocean O 2 trends: 1958–2015 Ito, Takamitsu; Minobe, Shoshiro; Long, Matthew C. ...
Geophysical research letters,
05/2017, Letnik:
44, Številka:
9
Journal Article
Recenzirano
Odprti dostop
Abstract
Historic observations of dissolved oxygen (O
2
) in the ocean are analyzed to quantify multidecadal trends and variability from 1958 to 2015. Additional quality control is applied, and the ...resultant oxygen anomaly field is used to quantify upper ocean O
2
trends at global and hemispheric scales. A widespread negative O
2
trend is beginning to emerge from the envelope of interannual variability. Ocean reanalysis data are used to evaluate relationships with changes in ocean heat content (OHC) and oxygen solubility (O
2,sat
). Global O
2
decline is evident after the 1980s, accompanied by an increase in global OHC. The global upper ocean O
2
inventory (0–1000 m) changed at the rate of −243 ± 124 T mol O
2
per decade. Further, the O
2
inventory is negatively correlated with the OHC (
r
= −0.86; 0–1000 m) and the regression coefficient of O
2
to OHC is approximately −8.2 ± 0.66 nmol O
2
J
−1
, on the same order of magnitude as the simulated O
2
‐heat relationship typically found in ocean climate models. Variability and trends in the observed upper ocean O
2
concentration are dominated by the apparent oxygen utilization component with relatively small contributions from O
2,sat
. This indicates that changing ocean circulation, mixing, and/or biochemical processes, rather than the direct thermally induced solubility effects, are the primary drivers for the observed O
2
changes. The spatial patterns of the multidecadal trend include regions of enhanced ocean deoxygenation including the subpolar North Pacific, eastern boundary upwelling systems, and tropical oxygen minimum zones. Further studies are warranted to understand and attribute the global O
2
trends and their regional expressions.
Plain Language Summary
This new paper describes the analysis of the dissolved oxygen in the global ocean using the most recent version of the World Ocean Database for the period of 1955 to 2015. After careful examination of the data, we found that a statistically significant, widespread O
2
decline is emerging beyond the envelope of natural fluctuations. Our study also reveals a tight relationship between O
2
inventories and the ocean heat content. The spatial pattern and magnitude of this relationship are consistent with expectations derived from mechanistic ocean climate models forced under climate warming scenarios. Taken together, the trends we document here are suggestive of the effects of the ocean warming beginning to supersede natural variability and emerge as a recognizable signal. This merits additional scrutiny over the coming years.
Key Points
A widespread negative O
2
trend is beginning to emerge from the envelope of interannual variability
The global ocean O
2
inventory is negatively correlated with the global ocean heat content
Variability and trends in the observed upper ocean O
2
concentration are dominated by the apparent oxygen utilization
The upper ocean heat content variability in the East/Japan Sea was investigated using a 40 year temperature and salinity data set from 1968 to 2007. Decadal variability was identified as the dominant ...mode of variability in the upper ocean (0–300 m) aside from the seasonal cycle. The decadal variability is strong to the west of northern Honshu, west of the Tsugaru Strait, and west of southern Hokkaido. Temperature anomalies at 50–125 m exhibit a large contribution to the decadal variability, particularly in the eastern part of the East/Japan Sea. The vertical structure of regressed temperature anomalies and the spatial patterns of regressed 10°C isotherms in the East/Japan Sea suggest that the decadal variability is related to upper ocean circulation in the East/Japan Sea. The decadal variability also exhibits an increasing trend, which indicates that the regions showing large decadal variations experienced warming on decadal time scales. Further analysis shows that the decadal variability in the East/Japan Sea is not locally isolated but is related to variability in the northwestern Pacific.
Key Points
Decadal variability of the upper‐ocean heat content in the East/Japan Sea (EJS)
Upper ocean warming related to the decadal variability in the EJS
Connectivity between the EJS and the northwestern Pacific
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