scholarly journals How Much of Monthly Subsurface Temperature Variability in the Equatorial Pacific Can Be Recovered by the Specification of Sea Surface Temperatures?

2014 ◽  
Vol 27 (4) ◽  
pp. 1559-1577 ◽  
Author(s):  
Arun Kumar ◽  
Hui Wang ◽  
Yan Xue ◽  
Wanqiu Wang
Keyword(s):  
Initial Conditions ◽  
Southern Oscillation ◽  
Coupled Model ◽  
Temperature Variability ◽  
Sea Surface ◽  
Model Integration ◽  
Ocean Temperature ◽  
Enso Prediction ◽  
Subsurface Ocean ◽  
Ocean Observing

Abstract The focus of the analysis is to investigate the question to what extent the specification of sea surface temperature (SST) in coupled model integration can impart realistic evolution of subsurface ocean temperature in the equatorial tropical Pacific. In the context of El Niño–Southern Oscillation (ENSO) prediction, the analysis is of importance from two aspects: such a system can be considered as a simple coupled ocean data assimilation system that can provide ocean initial conditions; and what additional components of the ocean observing system may be crucial for skillful ENSO prediction. The results indicate that coupled model integration where SST is continuously nudged toward the observed state can generate a realistic evolution of subsurface ocean temperature. The evolution of slow variability related to ENSO, in particular, has a good resemblance against the observational counterpart. The realism of subsurface ocean temperature variability is highest near the date line and least in the far eastern Pacific where the thermocline is shallowest. The results are also discussed in the context of ocean observing system requirements for ENSO prediction.

scholarly journals Spreading of warm ocean waters around Greenland as a possible cause for glacier acceleration

2012 ◽  
Vol 53 (60) ◽  
pp. 257-266 ◽  
Author(s):  
E. Rignot ◽  
I. Fenty ◽  
D. Menemenlis ◽  
Y. Xu
Keyword(s):  
Initial Conditions ◽  
Independent Study ◽  
Ocean Temperature ◽  
The North ◽  
Subsurface Ocean ◽  
Subsurface Waters ◽  
Glacier Flow ◽  
Horizontal Grid ◽  
Possible Cause

AbstractWe examine the pattern of spreading of warm subtropical-origin waters around Greenland for the years 1992–2009 using a high-resolution (4km horizontal grid) coupled ocean and sea-ice simulation. The simulation, provided by the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project, qualitatively reproduces the observed warming of subsurface waters in the subpolar gyre associated with changes of the North Atlantic atmospheric state that occurred in the mid-1990s. The modeled subsurface ocean temperature warmed by 1.5˚C in southeast and southwest Greenland during 1994–2005 and subsequently cooled by 0.5˚C; modeled subsurface ocean temperature increased by 2–2.5˚C in central and then northwest Greenland during 1997–2005 and stabilized thereafter, while it increased after 2005 by <0.5˚C in north Greenland. Comparisons with in situ measurements off the continental shelf in the Labrador and Irminger Seas indicate that the model initial conditions were 0.4˚C too warm in the south but the simulated warming is correctly reproduced; while measurements from eastern Baffin Bay reveal that the model initial conditions were 1.0˚C too cold in the northwest but the simulated ocean warming brought modeled temperature closer to observations, i.e. the simulated warming is 1.0˚C too large. At several key locations, the modeled oceanic changes off the shelf and below the seasonal mixed layer were rapidly transmitted to the shelf within troughs towards (model-unresolved) fjords. Unless blocked in the fjords by shallow sills, these warm subsurface waters had potential to propagate down the fjords and melt the glacier fronts. Based on model sensitivity simulations from an independent study (Xu and others, 2012), we show that the oceanic changes have very likely increased the subaqueous melt rates of the glacier fronts, and in turn impacted the rates of glacier flow.

scholarly journals An Analysis of the Temporal Evolution of ENSO Prediction Skill in the Context of the Equatorial Pacific Ocean Observing System

2015 ◽  
Vol 143 (8) ◽  
pp. 3204-3213 ◽  
Author(s):  
Arun Kumar ◽  
Mingyue Chen ◽  
Yan Xue ◽  
David Behringer
Keyword(s):  
Pacific Ocean ◽  
Time Evolution ◽  
Tropical Pacific ◽  
Sea Surface ◽  
Prediction Skill ◽  
Steady Increase ◽  
Coupled Models ◽  
Enso Prediction ◽  
Subsurface Ocean ◽  
Ocean Observations

Abstract Subsurface ocean observations in the equatorial tropical Pacific Ocean dramatically increased after the 1990s because of the completion of the TAO moored array and a steady increase in Argo floats. In this analysis the question explored is whether a steady increase in ocean observations can be discerned in improvements in skill of predicting sea surface temperature (SST) variability associated with El Niño–Southern Oscillation (ENSO)? The analysis is based on the time evolution of skill of sea surface temperatures in the equatorial tropical Pacific since 1982 based on a seasonal prediction system. It is found that for forecasts up to a 6-month lead time, a clear fingerprint of increases in subsurface ocean observations is not readily apparent in the time evolution of prediction skill that is dominated much more by the signal-to-noise consideration of SSTs to be predicted. Finding no clear relationship between an increase in ocean observations and prediction skill of SSTs, various possibilities for why it may be so are discussed. This discussion is to motivate further exploration on the question of the tropical Pacific observing system, its influence on the skill of ENSO prediction, and the capabilities of the current generation of coupled models and ocean data assimilation systems to take advantage of ocean observations.

scholarly journals Do Climate Models Capture the Tropical Influences on North Pacific Sea Surface Temperature Variability?

2011 ◽  
Vol 24 (23) ◽  
pp. 6203-6209 ◽  
Author(s):  
Fabian Lienert ◽  
John C. Fyfe ◽  
William J. Merryfield
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
North Pacific ◽  
Climate Models ◽  
Southern Oscillation ◽  
Temperature Variability ◽  
Sea Surface ◽  
Model Errors ◽  
The North ◽  
The North Pacific

Abstract This study evaluates the ability of global climate models to reproduce observed tropical influences on North Pacific Ocean sea surface temperature variability. In an ensemble of climate models, the study finds that the simulated North Pacific response to El Niño–Southern Oscillation (ENSO) forcing is systematically delayed relative to the observed response because of winter and spring mixed layers in the North Pacific that are too deep and air–sea feedbacks that are too weak. Model biases in mixed layer depth and air–sea feedbacks are also associated with a model mean ENSO-related signal in the North Pacific whose amplitude is overestimated by about 30%. The study also shows that simulated North Pacific variability has more power at lower frequencies than is observed because of model errors originating in the tropics and extratropics. Implications of these results for predictions on seasonal, decadal, and longer time scales are discussed.

scholarly journals Ocean and atmosphere coupling, connection between sub-polar Atlantic air temperature, Icelandic minimum and temperature in Serbia

2009 ◽  
Vol 89 (3) ◽  
pp. 165-176 ◽  
Author(s):  
Bosko Milovanovic ◽  
Milan Radovanovic ◽  
Vladan Ducic
Keyword(s):  
Cluster Analysis ◽  
Atlantic Ocean ◽  
Air Temperature ◽  
Atmospheric Pressure ◽  
Southern Oscillation ◽  
Hierarchical Cluster ◽  
Sea Surface ◽  
Ocean Temperature ◽  
Grid Cells ◽  
Oscillation Mechanism

In the presented paper correlation between the northern part of the Atlantic ocean (belt between 50-65?N) and the atmospheric pressure is examined. Connection between the ocean temperature and atmospheric pressure is the most obvious in the El Nino southern oscillation mechanism. Thus, so far it is not known that such a mechanism exist in the Atlantic ocean. The main accent in the presented paper is focused on the connection between Iceland low and the sea surface temperature (SST) in the subpolar part of the Atlantic ocean (used data are in grid 5x5?). By hierarchical cluster analysis five relatively unified clusters of sea surface temperatures grid cells are defined. By multiple linear regression, we examined the correlation between each of the depicted clusters with position and intensity of Iceland low, and identified the most important grid cells inside every cluster. The analysis of the relation between Iceland low and air temperature in Serbia and Belgrade has shown the strongest correlation for the longitude of this centre of action. .

scholarly journals Role of Kuroshio Current in fish resource variability off southwest Japan

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yushi Morioka ◽  
Sergey Varlamov ◽  
Yasumasa Miyazawa
Keyword(s):  
Rossby Waves ◽  
Kuroshio Current ◽  
Temperature Variability ◽  
Western Boundary ◽  
Ocean Temperature ◽  
Western Boundary Currents ◽  
Boundary Currents ◽  
Subsurface Ocean ◽  
Resource Variability ◽  
The Kuroshio

AbstractWestern boundary currents in the subtropics play a pivotal role in transporting warm water from the tropics that contribute to development of highly diverse marine ecosystem in the coastal regions. As one of the western boundary currents in the North Pacific, the Kuroshio Current (hereafter the Kuroshio) exerts great influences on biological resource variability off southwest Japan, but few studies have examined physical processes that attribute the coastal fish resource variability to the basin-scale Kuroshio variability. Using the high-quality fish catch data and high-resolution ocean reanalysis results, this study identifies statistical links of interannual fish resource variability off Sukumo Bay, Shikoku island of Japan, to subsurface ocean temperature variability in the Kuroshio. The subsurface ocean temperature variability off the south of Sukumo Bay exhibits vertically coherent structure with sea-surface height variability, which originates from the westward-propagating oceanic Rossby waves generated through surface wind anomalies in the Northwest Pacific. Although potential sources of the atmospheric variability remain unclarified, the remotely-induced oceanic Rossby waves contribute to fish resource variability off Sukumo Bay. These findings have potential applications to other coastal regions along the western boundary currents in the subtropics where the westward-propagating oceanic Rossby waves may contribute to coastal ocean temperature variability.

scholarly journals Reinitializing Sea Surface Temperature in the Ensemble Intermediate Coupled Model for Improved Forecasts

Axioms ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 189
Author(s):  
Sittisak Injan ◽  
Angkool Wangwongchai ◽  
Usa Humphries ◽  
Amir Khan ◽  
Abdullahi Yusuf
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Southern Oscillation ◽  
Coupled Model ◽  
Sea Surface ◽  
In Situ Data ◽  
The Pacific ◽  
Intermediate Coupled Model ◽  
Sea Surface Temperature Anomalies

The Ensemble Intermediate Coupled Model (EICM) is a model used for studying the El Niño-Southern Oscillation (ENSO) phenomenon in the Pacific Ocean, which is anomalies in the Sea Surface Temperature (SST) are observed. This research aims to implement Cressman to improve SST forecasts. The simulation considers two cases in this work: the control case and the Cressman initialized case. These cases are simulations using different inputs where the two inputs differ in terms of their resolution and data source. The Cressman method is used to initialize the model with an analysis product based on satellite data and in situ data such as ships, buoys, and Argo floats, with a resolution of 0.25 × 0.25 degrees. The results of this inclusion are the Cressman Initialized Ensemble Intermediate Coupled Model (CIEICM). Forecasting of the sea surface temperature anomalies was conducted using both the EICM and the CIEICM. The results show that the calculation of SST field from the CIEICM was more accurate than that from the EICM. The forecast using the CIEICM initialization with the higher-resolution satellite-based analysis at a 6-month lead time improved the root mean square deviation to 0.794 from 0.808 and the correlation coefficient to 0.630 from 0.611, compared the control model that was directly initialized with the low-resolution in-situ-based analysis.

scholarly journals Effects of forcing differences and initial conditions on inter-model agreement in the VolMIP volc-pinatubo-full experiment

2021 ◽  
Author(s):  
Davide Zanchettin ◽  
Claudia Timmreck ◽  
Myriam Khodri ◽  
Anja Schmidt ◽  
Matthew Toohey ◽  
...  
Keyword(s):  
Experimental Design ◽  
Initial Conditions ◽  
Southern Oscillation ◽  
Coupled Model ◽  
Model Intercomparison ◽  
Model Ensemble ◽  
Implementation Model ◽  
Volcanic Forcing ◽  
Intercomparison Project ◽  
The Tropics

Abstract. This paper provides initial results from a multi-model ensemble analysis based on the volc-pinatubo-full experiment performed within the Model Intercomparison Project on the climatic response to volcanic forcing (VolMIP) as part of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The volc-pinatubo-full experiment is based on ensemble of volcanic forcing-only climate simulations with the same volcanic aerosol dataset across the participating models (the 1991–1993 Pinatubo period from the CMIP6-GloSSAC dataset). The simulations are conducted within an idealized experimental design where initial states are sampled consistently across models from the CMIP6-piControl simulation providing unperturbed pre-industrial background conditions. The multi-model ensemble includes output from an initial set of six participating Earth system models (CanESM5, GISS-E2.1-G, IPSL-CM6A-LR, MIROC-E2SL, MPI-ESM1.2-LR and UKESM1). The results show overall good agreement between the different models on the global and hemispheric scale concerning the surface climate responses, thus demonstrating the overall effectiveness of VolMIP’s experimental design. However, small yet significant inter-model discrepancies are found in radiative fluxes especially in the tropics, that preliminary analyses link with minor differences in forcing implementation, model physics, notably aerosol-radiation interactions, the simulation and sampling of El Niño-Southern Oscillation (ENSO) and, possibly, the simulation of climate feedbacks operating in the tropics. We discuss the volc-pinatubo-full protocol and highlight the advantages of volcanic forcing experiments defined within a carefully designed protocol with respect to emerging modeling approaches based on large ensemble transient simulations. We identify how the VolMIP strategy could be improved in future phases of the initiative to ensure a cleaner sampling protocol with greater focus on the evolving state of ENSO in the pre-eruption period.

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