Analysis of the interannual variability in satellite gravity solutions : impact of climate modes on water mass displacements across continents and oceans

2021 ◽  
Author(s):  
Julia Pfeffer ◽  
Anny Cazenave ◽  
Anne Barnoud
Keyword(s):  
Climate Variability ◽  
Mass Transport ◽  
Interannual Variability ◽  
North Atlantic ◽  
North Pacific ◽  
Water Mass ◽  
Water Cycle ◽  
Satellite Gravity ◽  
Climate Modes ◽  
Shallow Seas

<p>The acquisition of time-lapse satellite gravity measurements during the GRACE and GRACE Follow On (FO) missions revolutionized our understanding of the Earth system, through the accurate quantification of the mass transport at global and regional scales. Largely related to the water cycle, along with some geophysical signals, decadal trends and seasonal cycles dominate the mass transport signals, constituting about 80 % of the total variability measured during GRACE (FO) missions. We focus here on the interannual variability, constituting the remaining 20 % of the signal, once linear trends and seasonal signals have been removed. Empirical orthogonal functions (EOFs) highlight the most prominent signals, including short-lived signals triggered by major earthquakes, interannual oscillations in the water cycle driven by the El Nino Southern Oscillation (ENSO) and significant decadal variability, potentially related to the Pacific Decadal Oscillation (PDO). The interpretation of such signals remains however limited due to the arbitrary nature of the statistical decomposition in eigen values. To overcome these limitations, we performed a LASSO (Least Absolute Shrinkage and Selection Operator) regression of eight climate indices, including ENSO, PDO, NPGO (North Pacific Gyre Oscillation), NAO (North Atlantic Oscillation), AO (Arctic Oscillation), AMO (Atlantic Multidecadal Oscillation), SAM (Southern Annular Mode) and IOD (Indian Ocean Dipole). The LASSO regularization, coupled with a cross-validation, proves to be remarkably successful in the automatic selection of relevant predictors of the climate variability for any geographical location in the world. As expected, ENSO and PDO impact the global water cycle both on land and in the ocean. The NPGO is also a major actor of the global climate, showing similarities with the PDO in the North Pacific. AO is generally favored over NAO, especially in the Mediteranean Sea and North Atlantic. SAM has a preponderant influence on the interannual variability of ocean bottom pressures in the Southern Ocean, and, in association with ENSO, modulates the interannual variability of ice mass loss in West Antarctica. AMO has a strong influence on the interannual water cycle along the Amazon river, due to the exchange of moisture in tropical regions. IOD has little to no impact on the interannual water cycle. All together, climate modes generate changes in the water mass distribution of about 100 mm for land, 50 mm for shallow seas and 15 mm for oceans. Climate modes account for a secondary but significant portion of the total interannual variability (at maximum 60% for shallow seas, 50 % for land and 40% for oceans). While such processes are insufficient to fully explain the complex nature of the interannual variability of water mass transport on a global scale, climate modes can be used to correct the GRACE (FO) measurements for a significant part of the natural climate variability and uncover smaller signals masked by such water mass transports.</p>

scholarly journals Analysis of the interannual variability in satellite gravity solutions: detection of climate modes in water mass displacements across continents and oceans

2021 ◽  
Author(s):  
Julia Pfeffer ◽  
Anny Cazenave ◽  
Anne Barnoud
Keyword(s):  
Mass Transport ◽  
Interannual Variability ◽  
Water Mass ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Natural Variability ◽  
Satellite Gravity ◽  
Climate Modes ◽  
Gravity Measurements ◽  
The Impact

Abstract This study analyzes the interannual variability of the water mass transport measured by satellite gravity missions in regard to eight major climate modes known to influence the Earth’s climate from regional to global scales. Using sparsity promoting techniques (i.e., LASSO), we automatically select the most relevant predictors of the climate variability among the eight candidates considered. The El Niño–Southern Oscillation, Southern Annular Mode and Arctic Oscillation are shown to account for a large part the interannual variability of the water mass transport observed in extratropical ocean basins (up to 40%) and shallow seas (up to 70%). A combination of three Pacific and one Atlantic modes is needed to account for most (up to 60%) of the interannual variability of the terrestrial water storage observed in the North Amazon, Parana and Zambezi basins. With our technique, the impact of climate modes on water mass changes can be tracked across distinct water reservoirs (oceans, continents and ice-covered regions) and we show that a combination of climate modes is necessary to explain at best the natural variability in water mass transport. The climate modes predictions based on LASSO inversions can be used to reduce the interannual variability in satellite gravity measurements and detect processes unrelated with the natural variability of climate but with similar spatio-temporal signatures. However, significant residuals in the satellite gravity measurements remain unexplained at interannual time scales and more complex models solving the water mass balance should be employed to better predict the variability of water mass distributions.

scholarly journals Analysis of the interannual variability in satellite gravity solutions: detection of climate modes fingerprints in water mass displacements across continents and oceans

2021 ◽  
Author(s):  
Julia Pfeffer ◽  
Anny Cazenave ◽  
Anne Barnoud
Keyword(s):  
Mass Transport ◽  
Interannual Variability ◽  
Water Mass ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Natural Variability ◽  
Satellite Gravity ◽  
Climate Modes ◽  
Gravity Measurements ◽  
The Impact

AbstractThis study analyzes the interannual variability of the water mass transport measured by satellite gravity missions in regard to eight major climate modes known to influence the Earth’s climate from regional to global scales. Using sparsity promoting techniques (i.e., LASSO), we automatically select the most relevant predictors of the climate variability among the eight candidates considered. The El Niño–Southern Oscillation, Southern Annular Mode and Arctic Oscillation are shown to account for a large part the interannual variability of the water mass transport observed in extratropical ocean basins (up to 40%) and shallow seas (up to 70%). A combination of three Pacific and one Atlantic modes is needed to account for most (up to 60%) of the interannual variability of the terrestrial water storage observed in the North Amazon, Parana and Zambezi basins. With our technique, the impact of climate modes on water mass changes can be tracked across distinct water reservoirs (oceans, continents and ice-covered regions) and we show that a combination of climate modes is necessary to explain at best the natural variability in water mass transport. The climate modes predictions based on LASSO inversions can be used to reduce the inter-annual variability in satellite gravity measurements and detect processes unrelated with the natural variability of climate but with similar spatio-temporal signatures. However, significant residuals in the satellite gravity measurements remain unexplained at inter-annual time scales and more complex models solving the water mass balance should be employed to better predict the variability of water mass distributions.

scholarly journals Relative timing of precipitation and ocean circulation changes in the western equatorial Atlantic over the last 45 kyr

2018 ◽  
Vol 14 (9) ◽  
pp. 1315-1330 ◽  
Author(s):  
Claire Waelbroeck ◽  
Sylvain Pichat ◽  
Evelyn Böhm ◽  
Bryan C. Lougheed ◽  
Davide Faranda ◽  
...  
Keyword(s):  
Mass Transport ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Wavelet Transforms ◽  
Water Mass ◽  
Sediment Cores ◽  
Equatorial Atlantic ◽  
The North ◽  
Atmospheric Changes ◽  
Circulation Changes

Abstract. Thanks to its optimal location on the northern Brazilian margin, core MD09-3257 records both ocean circulation and atmospheric changes. The latter occur locally in the form of increased rainfall on the adjacent continent during the cold intervals recorded in Greenland ice and northern North Atlantic sediment cores (i.e., Greenland stadials). These rainfall events are recorded in MD09-3257 as peaks in ln(Ti ∕ Ca). New sedimentary Pa ∕ Th data indicate that mid-depth western equatorial water mass transport decreased during all of the Greenland stadials of the last 40 kyr. Using cross-wavelet transforms and spectrogram analysis, we assess the relative phase between the MD09-3257 sedimentary Pa ∕ Th and ln(Ti ∕ Ca) signals. We show that decreased water mass transport between a depth of ∼1300 and 2300 m in the western equatorial Atlantic preceded increased rainfall over the adjacent continent by 120 to 400 yr at Dansgaard–Oeschger (D–O) frequencies, and by 280 to 980 yr at Heinrich-like frequencies. We suggest that the large lead of ocean circulation changes with respect to changes in tropical South American precipitation at Heinrich-like frequencies is related to the effect of a positive feedback involving iceberg discharges in the North Atlantic. In contrast, the absence of widespread ice rafted detrital layers in North Atlantic cores during D–O stadials supports the hypothesis that a feedback such as this was not triggered in the case of D–O stadials, with circulation slowdowns and subsequent changes remaining more limited during D–O stadials than Heinrich stadials.

Seasonal variability of the net water-mass transport among the four major basins 

2021 ◽  
Author(s):  
David Garcia-Garcia ◽  
Isabel Vigo ◽  
Mario Trottini ◽  
Juan Vargas
Keyword(s):  
Mass Transport ◽  
Seasonal Variability ◽  
Water Mass ◽  
Water Cycle ◽  
Boreal Summer ◽  
Fundamental Limitations ◽  
Global Water Cycle ◽  
The Pacific ◽  
Grace Satellite ◽  
Evaporation Minus Precipitation

<p>Global water cycle involves water-mass transport on land, atmosphere, ocean, and among them. Quantification of such transport, and especially its time evolution, is essential to identify footprints of the climate change and helps to constrain and improve climatic models. In the ocean, net water-mass transport among the ocean basins is a key, but poorly estimated parameter presently. We propose a new methodology that incorporates the time-variable gravity observations from the GRACE satellite (2003-2016) to estimate the change of water content, and that overcomes some fundamental limitations of existing approaches. We show that the Pacific and Arctic Oceans receive an average of 1916 (95% confidence interval [1812, 2021]) Gt/month (~0.72 ± 0.02 Sv) of excess freshwater from the atmosphere and the continents that gets discharged into the Atlantic and Indian Oceans, where net evaporation minus precipitation returns the water to complete the cycle. This salty water-mass transport from the Pacific and Arctic Oceans to the Atlantic and Indian Oceans show a clear seasonal variability, with a maximum transport of 3000 Gt/month during boreal summer, a minimum of 1000 Gt/month or less on February, Mars, and November.</p><p>This research has been primarily supported by the Spanish Ministerio de Ciencia, Innovación and Universidades research project DEEP-MAPS (RTI2018-093874-B-I00).</p>

scholarly journals Variability of the Winter Wind Waves and Swell in the North Atlantic and North Pacific as Revealed by the Voluntary Observing Ship Data

2006 ◽  
Vol 19 (21) ◽  
pp. 5667-5685 ◽  
Author(s):  
Sergey K. Gulev ◽  
Vika Grigorieva
Keyword(s):  
Interannual Variability ◽  
Wave Height ◽  
North Atlantic ◽  
North Pacific ◽  
Significant Wave Height ◽  
Wind Wave ◽  
Significant Wave ◽  
The North ◽  
The North Atlantic ◽  
Wind Sea

Abstract This paper analyses secular changes and interannual variability in the wind wave, swell, and significant wave height (SWH) characteristics over the North Atlantic and North Pacific on the basis of wind wave climatology derived from the visual wave observations of voluntary observing ship (VOS) officers. These data are available from the International Comprehensive Ocean–Atmosphere Data Set (ICOADS) collection of surface meteorological observations for 1958–2002, but require much more complicated preprocessing than standard meteorological variables such as sea level pressure, temperature, and wind. Visual VOS data allow for separate analysis of changes in wind sea and swell, as well as in significant wave height, which has been derived from wind sea and swell estimates. In both North Atlantic and North Pacific midlatitudes winter significant wave height shows a secular increase from 10 to 40 cm decade−1 during the last 45 yr. However, in the North Atlantic the patterns of trend changes for wind sea and swell are quite different from each other, showing opposite signs of changes in the northeast Atlantic. Trend patterns of wind sea, swell, and SWH in the North Pacific are more consistent with each other. Qualitatively the same conclusions hold for the analysis of interannual variability whose leading modes demonstrate noticeable differences for wind sea and swell. Statistical analysis shows that variability in wind sea is closely associated with the local wind speed, while swell changes can be driven by the variations in the cyclone counts, implying the importance of forcing frequency for the resulting changes in significant wave height. This mechanism of differences in variability patterns of wind sea and swell is likely more realistic than the northeastward propagation of swells from the regions from which the wind sea signal originates.

scholarly journals Ocean Waves and Teleconnection Patterns in the Northern Hemisphere

2013 ◽  
Vol 26 (21) ◽  
pp. 8654-8670 ◽  
Author(s):  
Tomoya Shimura ◽  
Nobuhito Mori ◽  
Hajime Mase
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
North Atlantic ◽  
North Pacific ◽  
Wave Climate ◽  
Teleconnection Pattern ◽  
Teleconnection Patterns ◽  
The North ◽  
Shaped Pattern ◽  
The North Pacific

Abstract Understanding long-term, ocean wave climate variability is important to assess climate change impacts on coastal and ocean physics and engineering. Teleconnection patterns can represent wave climate variability in the context of climate change. The objective of this study is to identify how large-scale spatial distributions of wave heights vary on a monthly basis and how they are influenced by various teleconnection patterns using reanalysis datasets. The wave height climate responses to teleconnection patterns in the eastern part of the North Pacific and North Atlantic are more sensible than in the corresponding western parts. The dominant spatial patterns of monthly averaged wave height variability in winter were obtained by empirical orthogonal function analysis. The three dominant patterns in the North Pacific and North Atlantic are similar. It is remarkable that one of the three dominant patterns, a band-shaped pattern, exhibits a strong relation to the teleconnection pattern in each ocean. The band-shaped pattern for the North Pacific was investigated in detail and found to be related to the west Pacific (WP) pattern. Where and how each teleconnection pattern influences wave climate becomes apparent especially during winter.

scholarly journals Natural variability in the surface ocean carbonate ion concentration

2015 ◽  
Vol 12 (21) ◽  
pp. 6321-6335 ◽  
Author(s):  
N. S. Lovenduski ◽  
M. C. Long ◽  
K. Lindsay
Keyword(s):  
Interannual Variability ◽  
North Atlantic ◽  
North Pacific ◽  
Tropical Pacific ◽  
Ion Concentration ◽  
Saturation State ◽  
Surface Ocean ◽  
The North ◽  
Carbonate Ion ◽  
The Tropical Pacific

Abstract. We investigate variability in the surface ocean carbonate ion concentration ([CO32−]) on the basis of a~long control simulation with an Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32−] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32−] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32−] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite) are already or nearly detectable at the sustained, open-ocean time series sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32−] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño–Southern Oscillation. In the North Pacific, surface [CO32−] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20–30-year periods. North Atlantic [CO32−] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the interpretation of trends calculated from spatially and temporally sparse observations.

scholarly journals Natural variability in the surface ocean carbonate ion concentration

2015 ◽  
Vol 12 (15) ◽  
pp. 13123-13157
Author(s):  
N. S. Lovenduski ◽  
M. C. Long ◽  
K. Lindsay
Keyword(s):  
Interannual Variability ◽  
North Atlantic ◽  
North Pacific ◽  
Tropical Pacific ◽  
Ion Concentration ◽  
Saturation State ◽  
Surface Ocean ◽  
The North ◽  
Carbonate Ion ◽  
The Tropical Pacific

Abstract. We investigate variability in the surface ocean carbonate ion concentration ([CO32−]) on the basis of a long control simulation with a fully-coupled Earth System Model. The simulation is run with a prescribed, pre-industrial atmospheric CO2 concentration for 1000 years, permitting investigation of natural [CO32−] variability on interannual to multi-decadal timescales. We find high interannual variability in surface [CO32−] in the tropical Pacific and at the boundaries between the subtropical and subpolar gyres in the Northern Hemisphere, and relatively low interannual variability in the centers of the subtropical gyres and in the Southern Ocean. Statistical analysis of modeled [CO32−] variance and autocorrelation suggests that significant anthropogenic trends in the saturation state of aragonite (Ωaragonite) are already or nearly detectable at the sustained, open-ocean timeseries sites, whereas several decades of observations are required to detect anthropogenic trends in Ωaragonite in the tropical Pacific, North Pacific, and North Atlantic. The detection timescale for anthropogenic trends in pH is shorter than that for Ωaragonite, due to smaller noise-to-signal ratios and lower autocorrelation in pH. In the tropical Pacific, the leading mode of surface [CO32−] variability is primarily driven by variations in the vertical advection of dissolved inorganic carbon (DIC) in association with El Niño–Southern Oscillation. In the North Pacific, surface [CO32−] variability is caused by circulation-driven variations in surface DIC and strongly correlated with the Pacific Decadal Oscillation, with peak spectral power at 20–30 year periods. North Atlantic [CO32−] variability is also driven by variations in surface DIC, and exhibits weak correlations with both the North Atlantic Oscillation and the Atlantic Multidecadal Oscillation. As the scientific community seeks to detect the anthropogenic influence on ocean carbonate chemistry, these results will aid the interpretation of trends calculated from spatially- and temporally-sparse observations.

Sign in / Sign up

Export Citation Format

Share Document