scholarly journals Ocean Reanalyses

2018 ◽  
Author(s):  
Keith Haines
Keyword(s):  
Ocean Reanalyses

The Importance of Central Pacific Meridional Heat Advection to the Development of ENSO

2021 ◽  
pp. 1-59
Author(s):  
Caihong Wen ◽  
Arun Kumar ◽  
Michelle L’ Heureux ◽  
Yan Xue ◽  
Emily Becker
Keyword(s):  
Water Volume ◽  
Primary Role ◽  
Equatorial Pacific Ocean ◽  
Central Pacific ◽  
Enso Prediction ◽  
Enso Events ◽  
Ocean Reanalyses ◽  
Equatorial Thermocline ◽  
Warm Water Volume ◽  
The Relationship

AbstractThe relationship between the Warm Water Volume (WWV) ENSO precursor and ENSO SST weakened substantially after ~2000, coinciding with a degradation in dynamical model ENSO prediction skill. It is important to understand the drivers of the equatorial thermocline temperature variations and their linkage to ENSO onsets. In this study, a set of ocean reanalyses is employed to assess factors responsible for the variation of the equatorial Pacific Ocean thermocline during 1982-2019. Off-equatorial thermocline temperature anomalies carried equatorward by the mean meridional currents associated with Pacific Tropical Cells are shown to play an important role in modulating the central equatorial thermocline variations, which is rarely discussed in the literature. Further, ENSO events are delineated into two groups based on precursor mechanisms: the western equatorial type (WEP) ENSO, when the central equatorial thermocline is mainly influenced by the zonal propagation of anomalies from the western Pacific, and the off-equatorial central Pacific (OCP) ENSO, when off-equatorial central thermocline anomalies play the primary role. WWV is found to precede all WEP ENSO by 6-9 months, while the correlation is substantially lower for OCP ENSO events. In contrast, the central tropical Pacific (CTP) precursor, which includes off-equatorial thermocline signals, has a very robust lead correlation with the OCP ENSO. Most OCP ENSO events are found to follow the same ENSO conditions, and the number of OCP ENSO increases substantially since the 21st century. These results highlight the importance of monitoring off-equatorial subsurface preconditions for ENSO prediction and to understand multi-year ENSO.

scholarly journals An assessment of upper ocean salinity content from the Ocean Reanalyses Inter-comparison Project (ORA-IP)

2015 ◽  
Vol 49 (3) ◽  
pp. 1009-1029 ◽  
Author(s):  
L. Shi ◽  
O. Alves ◽  
R. Wedd ◽  
M. A. Balmaseda ◽  
Y. Chang ◽  
...  
Keyword(s):  
Upper Ocean ◽  
Ocean Reanalyses ◽  
Ocean Salinity

scholarly journals The Mean State and Variability of the North Atlantic Circulation: A Perspective From Ocean Reanalyses

2019 ◽  
Vol 124 (12) ◽  
pp. 9141-9170 ◽  
Author(s):  
L. C. Jackson ◽  
C. Dubois ◽  
G. Forget ◽  
K. Haines ◽  
M. Harrison ◽  
...  
Keyword(s):  
North Atlantic ◽  
The North ◽  
Ocean Reanalyses ◽  
The Mean ◽  
The North Atlantic ◽  
Mean State

Salinity Assimilation Using S(T): Covariance Relationships

2006 ◽  
Vol 134 (3) ◽  
pp. 759-771 ◽  
Author(s):  
K. Haines ◽  
J. D. Blower ◽  
J-P. Drecourt ◽  
C. Liu ◽  
A. Vidard ◽  
...  
Keyword(s):  
General Circulation ◽  
Power Spectra ◽  
General Circulation Models ◽  
Temporal Variations ◽  
Ocean Model ◽  
Spatial Covariance ◽  
Ocean Reanalysis ◽  
Argo Data ◽  
Ocean Reanalyses ◽  
Salinity Data

Abstract Assimilation of salinity into ocean and climate general circulation models is a very important problem. Argo data now provide far more salinity observations than ever before. In addition, a good analysis of salinity over time in ocean reanalyses can give important results for understanding climate change. Here it is shown from the historical ocean database that over large regions of the globe (mainly midlatitudes and lower latitudes) variance of salinity on an isotherm S(T) is often less than variance measured at a particular depth S(z). It is also shown that the dominant temporal variations in S(T) occur more slowly than variations in S(z), based on power spectra from the Bermuda time series. From ocean models it is shown that the horizontal spatial covariance of S(T) often has larger scales than S(z). These observations suggest an assimilation method based on analyzing S(T). An algorithm for assimilating salinity data on isotherms is then presented, and it is shown how this algorithm produces orthogonal salinity increments to those produced during the assimilation of temperature profiles. It is argued that the larger space and time scales can be used for the S(T) assimilation, leading to better use of scarce salinity observations. Results of applying the salinity assimilation algorithm to a single analysis time within the ECMWF seasonal forecasting ocean model are also shown. The separate salinity increments coming from temperature and salinity data are identified, and the independence of these increments is demonstrated. Results of an ocean reanalysis with this method will appear in a future paper.

scholarly journals Annual Sea Level Changes on the North American Northeast Coast: Influence of Local Winds and Barotropic Motions

2016 ◽  
Vol 29 (13) ◽  
pp. 4801-4816 ◽  
Author(s):  
Christopher G. Piecuch ◽  
Sönke Dangendorf ◽  
Rui M. Ponte ◽  
Marta Marcos
Keyword(s):  
Sea Level ◽  
Wind Stress ◽  
Ocean Circulation ◽  
Tide Gauge ◽  
Sea Level Changes ◽  
Tide Gauge Records ◽  
Barotropic Model ◽  
The North ◽  
Ocean Reanalyses ◽  
Coastal Sea

Abstract Understanding the relationship between coastal sea level and the variable ocean circulation is crucial for interpreting tide gauge records and projecting sea level rise. In this study, annual sea level records (adjusted for the inverted barometer effect) from tide gauges along the North American northeast coast over 1980–2010 are compared to a set of data-assimilating ocean reanalysis products as well as a global barotropic model solution forced with wind stress and barometric pressure. Correspondence between models and data depends strongly on model and location. At sites north of Cape Hatteras, the barotropic model shows as much (if not more) skill than ocean reanalyses, explaining about 50% of the variance in the adjusted annual tide gauge sea level records. Additional numerical experiments show that annual sea level changes along this coast from the barotropic model are driven by local wind stress over the continental shelf and slope. This result is interpreted in the light of a simple dynamic framework, wherein bottom friction balances surface wind stress in the alongshore direction and geostrophy holds in the across-shore direction. Results highlight the importance of barotropic dynamics on coastal sea level changes on interannual and decadal time scales; they also have implications for diagnosing the uncertainties in current ocean reanalyses, using tide gauge records to infer past changes in ocean circulation, and identifying the physical mechanisms responsible for projected future regional sea level rise.

Depth and properties of freshwater export from the Greenland Ice Sheet modulated by ice-ocean processes

2020 ◽  
Author(s):  
Donald Slater ◽  
Fiamma Straneo
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Regional Variability ◽  
Near Surface ◽  
Fjord Circulation ◽  
Ocean Reanalyses ◽  
Freshwater Export ◽  
Ocean Processes

<p>Freshwater export from the Greenland Ice Sheet to the surrounding ocean has increased by 50% since the early 1990s, and may triple over the coming century under high greenhouse gas emissions. This increasing freshwater has the potential to influence both the regional and large-scale ocean, including marine ecosystems. Yet quantification of these impacts remains uncertain in part due to poor characterization of freshwater export, and in particular the transformation of freshwater around the ice sheet margin by ice-ocean processes, such as submarine melting, plumes and fjord circulation. Here, we combine in-situ observations, ocean reanalyses and simple models for ice-ocean processes to estimate the depth and properties of freshwater export around the full Greenland ice sheet from 1991 to present. The results show significant regional variability driven primarily by the depth at which freshwater runoff leaves the ice sheet. Areas with deeply-grounded marine-terminating glaciers are likely to export freshwater to the ocean as a dilute mixture of freshwater and externally-sourced deep water masses, while freshwater from areas with many land-terminating glaciers is exported as a more concentrated mixture of freshwater and near-surface waters. A handful of large glacier-fjord systems dominate ice sheet freshwater export, and the vast majority of freshwater export occurs subsurface. Our results provide an ice sheet-wide first-order characterization of how ice-ocean processes modulate Greenland freshwater export, and are an important step towards accurate representation of Greenland freshwater in large-scale ocean models.</p>

scholarly journals An ensemble of ocean reanalyses for 1815-2013 with sparse observational input

2016 ◽  
Vol 121 (9) ◽  
pp. 6891-6910 ◽  
Author(s):  
Benjamin S. Giese ◽  
Howard F. Seidel ◽  
Gilbert P. Compo ◽  
Prashant D. Sardeshmukh
Keyword(s):  
Ocean Reanalyses

scholarly journals Intercomparison of the Gulf Stream in ocean reanalyses: 1993−2010

2018 ◽  
Vol 125 ◽  
pp. 1-21 ◽  
Author(s):  
Lequan Chi ◽  
Christopher L.P. Wolfe ◽  
Sultan Hameed
Keyword(s):  
Gulf Stream ◽  
Ocean Reanalyses
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