Surface salinity of the North Atlantic: Can we reconstruct its fluctuations over the last one hundred years?

Reverdin, Gilles; Cayan, Daniel R.; Dooley, H. D.; Ellett, D. J.; Levitus, Sydney; Penhoat, Yves du; Dessier, Alain

doi:10.1016/0079-6611(94)90021-3

Cited by 26 publications

(44 citation statements)

References 21 publications

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“…Since the observed FSC time series is inhomogeneously sampled and with more energy on the seasonal cycle than on lower frequency variations, aliasing is a problem [Reverdin et al, 1994]. Reverdin er al.…”

Section: Discussionmentioning

confidence: 99%

“…[1994] found that the use of available surface data can critically reduce the aliasing problem in the discussed FSC series. With support from the daily SST measurements from the Faroe Shelf and the fact that the model is able to simulate the observed surface temperatures on the Shetland Shelf practically perfectly (not shown), it should therefore be possible to further pursue the approach by Reverdin et al [1994].…”

Section: Discussionmentioning

confidence: 99%

“…Although frequently sampled, there are periods with only one or two observations per year and with a highly variable seasonal cycle in the FSC , this can lead to difficulties in uniquely identifying the seasonal cycle and the inter-annual temperature anomalies in the series. The consequence of this can be that spurious temperature and salinity anomalies are deduced from the data material [Reverdin et al, 1994]. Here we present a hind-cast simulation with a regional version of the Miami Isopycnic Coordinate Ocean Model (MICOM) [Bleck et al, 1992] to 1) evaluate one aspect of the model performance, to 2) assess whether the observed time series can be complimented for the period 1948 to 2001, and to 3) provide guidance for the future sampling strategy of the Faroes-Scotland transect.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal to decadal temperature variations in the Faroe—Shetland inflow waters

Hátún

Sandø²,

Drange³

et al. 2005

The Nordic Seas: An Integrated Perspective Oceanography, Climatology, Biogeochemistry, and Modeling

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A 53 years hind-cast simulation with a regional version of the Nansen Center version of the Miami Isopycnic Coordinate Ocean Model (MICOM) has been conducted to explore the nature of the observed seasonal to inter-annual variations in the temperature of the pole-ward flowing Atlantic Water (AW) crossing the IcelandScotland Ridge (ISR). It is found that the simulated long-term temperature variations closely resemble observations south of the ridge (Rockall Trough), north of the ridge (Svinøy section) and between (Faroe Shetland Channel, FSC). The simulated temperature on the Faroe Shelf is also compared to daily temperature observations from Mykines, revealing realistic long-term temperature variations, seasonal variations and a realistic seasonal modulation. The simulated time series in the FSC indicates that the phase and amplitude of the annual temperature cycle of the AW have varied by almost one month and 0.15 ºC between the 1960s and 2001, illustrating the difficulty in unambiguously removing the seasonal cycle from the, sparsely sampled, time series. It is argued that the simulated time series can be used to complement the observed time series in periods with sparse sampling. Specifically, the observation-based cold anomaly in the late 1960s and the warming in the early 1980s should be treated with caution. Finally, the analysis indicates that it is not advisable to survey the hydrographic section less than four times a year if reliable decadal scale temperature variations are of interest.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Seasonal to decadal temperature variations in the Faroe—Shetland inflow waters

Hátún

Sandø²,

Drange³

et al. 2005

The Nordic Seas: An Integrated Perspective Oceanography, Climatology, Biogeochemistry, and Modeling

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“…org)]. Its monitoring has long been very difficult to achieve (Delcroix et al 2005;Reverdin et al 2007), and the accuracy with which this was done has long been rather low, both because of difficulties of gathering data with sufficient accuracy and because of insufficiencies in sampling (Bingham et al 2002). The bulk of the data typically originated either from samples collected from a bucket [see Reverdin et al (1994) for discussion of the accuracy of those data] or, since the early 1990s, from thermosalinographs placed on an interior circuit deriving the seawater from an intake placed at depths varying from less than 3 m to close to 15 m [see e.g., the Observatoire de Recherche en Environnement (ORE) SSS Web site (http://www.legos.obs-mip.fr/observations/ sss/) for typical installations on merchant vessels].…”

Section: Introductionmentioning

confidence: 99%

Surface Salinity Measurements—COSMOS 2005 Experiment in the Bay of Biscay

Reverdin

Blouch

Boutin

et al. 2007

Journal of Atmospheric and Oceanic Technology

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Sea surface salinity (SSS) data were collected in the Bay of Biscay between April and November 2005. The major source of data is 15 surface drifters deployed during the COSMOS experiment in early April and early May 2005 [12 from the Scripps Instution of Oceanography (SIO) and 3 from METOCEAN]. This is complemented by thermosalinograph (TSG) data from four French research vessels and four merchant vessels, from salinity profiles collected by Argo profiling floats and CTD casts, and from surface samples during two cruises. Time during the two cruises was dedicated to direct inspection of the drifters, recovering some, and providing validation data. This dataset provides a unique opportunity to estimate the accuracy of the SSS data and to evaluate the long-term performance of the drifter salinities. Some of the TSG SSS data were noisy, presumably from bubbles. The TSG data from the research vessels needed to be corrected from biases, which are very commonly larger than 0.1 pss-78 (practical salinity scale), and which in some instances evolved quickly from day to day. These corrections are only available when samples were collected or ancillary data are available (e.g., from CTD profiles). The resulting accuracy of the corrected TSG dataset, which varies strongly in time, is discussed. The surface drifter SSS data presented anomalous daytime values during days with strong surface warming. These data had to be excluded from the dataset. The drifter SSS presented initial biases in the range 0.009 to Ϫ0.026 pss-78. The (usually) negative bias increased by an average of Ϫ0.007 pss-78 during the average 65-day period before the COSMOS-2 cruise on 22-27 June. High chlorophyll derived from satellite ocean color, and therefore high density of phytoplanktonic cells, is observed in Medium Resolution Imaging Spectrometer (MERIS)/Moderate Resolution Imaging Spectroradiometer (MODIS) composites during part of the period, in particular in late April or early May. No correlation was found between the change in bias and the estimated surface chlorophyll. Evolution during the following summer months is harder to ascertain. For three buoys, there is little change in bias, but for two others, there could have been an increase in bias by up to 0.03 or 0.04 pss-78 during July-August. Seven drifters were recovered in the autumn, which provide recovery or postrecovery estimates of the biases, suggesting in three cases (out of seven) a large (0.02-0.03 pss-78) increase in bias during the autumn months, but no significant increase for the other four drifters.

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“…Although that salinity change must not be considered as instantaneous, but rather as a time integrated change in the water column, a change of 0.3 over a 200 m water column is important. The order of magnitude of this balance was deduced by Pérez et al (2000) using data and estimation by Rogers and Van Loon (1979) and Reverdin et al (1994). The order of magnitude of their and our balances are similar, when taking into account both evaporation/precipitation and river run-off.…”

Section: Sea Surface Temperature Variability and The Surface Signal Omentioning

confidence: 99%

Daily scale wintertime sea surface temperature and IPC-Navidad variability in the southern Bay of Biscay from 1981 to 2010

et al. 2013

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Abstract. The combination of remotely sensed gappy Sea surface temperature (SST) images with the missing data filling DINEOF (data interpolating empirical orthogonal functions) technique, followed by a principal component analysis of the reconstructed data, has been used to identify the time evolution and the daily scale variability of the wintertime surface signal of the Iberian Poleward Current (IPC), or Navidad, during the 1981-2010 period. An exhaustive comparison with the existing bibliography, and the vertical temperature and salinity profiles related to its extremes over the Bay of Biscay area, show that the obtained time series accurately reflect the IPC-Navidad variability. Once a time series for the evolution of the SST signal of the current over the last decades is well established, this time series is used to propose a physical mechanism in relation to the variability of the IPC-Navidad, involving both atmospheric and oceanic variables. According to the proposed mechanism, an atmospheric circulation anomaly observed in both the 500 hPa and the surface levels generates atmospheric surface level pressure, wind-stress and heat-flux anomalies. In turn, those surface level atmospheric anomalies induce mutually coherent SST and sea level anomalies over the North Atlantic area, and locally, in the Bay of Biscay area. These anomalies, both locally over the Bay of Biscay area and over the North Atlantic, are in agreement with several mechanisms that have separately been related to the variability of the IPC-Navidad, i.e. the south-westerly winds, the joint effect of baroclinicity and relief (JEBAR) effect, the topographic β effect and a weakened North Atlantic gyre.

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Surface salinity of the North Atlantic: Can we reconstruct its fluctuations over the last one hundred years?

Cited by 26 publications

References 21 publications

Seasonal to decadal temperature variations in the Faroe—Shetland inflow waters

Seasonal to decadal temperature variations in the Faroe—Shetland inflow waters

Surface Salinity Measurements—COSMOS 2005 Experiment in the Bay of Biscay

Daily scale wintertime sea surface temperature and IPC-Navidad variability in the southern Bay of Biscay from 1981 to 2010

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