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Salinity Profile Estimation in the Pacific Ocean from Satellite Surface Salinity Observations1. Introduction Salinity plays a significant role in the ocean circulation and the Earth global hydrological cycle. Salinity, along with ocean temperature, is required to compute ocean density and provides key information about water mass formation, mixed layer depth, barrier layer depth, and geostrophic circulation ( de Boyer Montégut et al. 2007 ; Helber et al. 2010 ; Qin et al. 2015 ; Rao and Sivakumar 2003 ; Wang and Zhang 2012 ). Further, sea surface salinity is a key variable
1. Introduction Salinity plays a significant role in the ocean circulation and the Earth global hydrological cycle. Salinity, along with ocean temperature, is required to compute ocean density and provides key information about water mass formation, mixed layer depth, barrier layer depth, and geostrophic circulation ( de Boyer Montégut et al. 2007 ; Helber et al. 2010 ; Qin et al. 2015 ; Rao and Sivakumar 2003 ; Wang and Zhang 2012 ). Further, sea surface salinity is a key variable
1. Introduction The measurement of absolute salinity in the ocean during campaigns at sea is problematic because salinity is not obtained through direct measurement but instead is calculated from measurement of electrical conductivity. However, conductivity only slightly depends on salinity and mainly depends on temperature, the effect of which must then be filtered out very precisely. It is thus extremely important that the conductivity sensors respond perfectly to the quick temperature
1. Introduction The measurement of absolute salinity in the ocean during campaigns at sea is problematic because salinity is not obtained through direct measurement but instead is calculated from measurement of electrical conductivity. However, conductivity only slightly depends on salinity and mainly depends on temperature, the effect of which must then be filtered out very precisely. It is thus extremely important that the conductivity sensors respond perfectly to the quick temperature
1. Introduction Two salinity remote sensing satellite missions are expected to be launched in 2009–10. One mission is the Aquarius/Satelite de Aplicaciones Cientificas-D (SAC-D) science mission, developed jointly by the National Aeronautics and Space Administration (NASA) and the Comisión Nacional de Actividades Espaciales (CONAE), the Argentine space agency ( Lagerloef et al. 1995 , 2008 ; Koblinsky et al. 2003 ; Le Vine et al. 2007 ). The other mission is the Soil Moisture and Ocean
1. Introduction Two salinity remote sensing satellite missions are expected to be launched in 2009–10. One mission is the Aquarius/Satelite de Aplicaciones Cientificas-D (SAC-D) science mission, developed jointly by the National Aeronautics and Space Administration (NASA) and the Comisión Nacional de Actividades Espaciales (CONAE), the Argentine space agency ( Lagerloef et al. 1995 , 2008 ; Koblinsky et al. 2003 ; Le Vine et al. 2007 ). The other mission is the Soil Moisture and Ocean
1. Introduction Salinity is one of the fundamental ocean variables that are routinely measured, and variations in salinity have been used extensively in climate studies. First, ocean salinity is strongly impacted by air–sea freshwater exchange, land freshwater discharges, sea ice formation and melting, and ocean dynamics ( Rao and Sivakumar 2003 ; Foltz et al. 2004 ; Dong et al. 2014 ; Haumann et al. 2016 ; Liu et al. 2019 ). Since salinity is easier to measure than the air–sea freshwater
1. Introduction Salinity is one of the fundamental ocean variables that are routinely measured, and variations in salinity have been used extensively in climate studies. First, ocean salinity is strongly impacted by air–sea freshwater exchange, land freshwater discharges, sea ice formation and melting, and ocean dynamics ( Rao and Sivakumar 2003 ; Foltz et al. 2004 ; Dong et al. 2014 ; Haumann et al. 2016 ; Liu et al. 2019 ). Since salinity is easier to measure than the air–sea freshwater
97% of the global water inventory, with 80% of the surface water flux occurring over the oceans ( Schmitt 1995 ). The global ocean’s salinity field reflects the large-scale long-term balance between the surface freshwater flux [evaporation minus precipitation (EP) and terrestrial runoff minus the total surface freshwater flux ( F W )] and the ocean’s advective and mixing processes. Any change in the hydrological cycle, therefore, will be reflected in the ocean salinity field. Large and coherent
97% of the global water inventory, with 80% of the surface water flux occurring over the oceans ( Schmitt 1995 ). The global ocean’s salinity field reflects the large-scale long-term balance between the surface freshwater flux [evaporation minus precipitation (EP) and terrestrial runoff minus the total surface freshwater flux ( F W )] and the ocean’s advective and mixing processes. Any change in the hydrological cycle, therefore, will be reflected in the ocean salinity field. Large and coherent
1. Introduction An important component of the calibration and validation effort of any satellite mission is the comparison between remotely sensed and in situ measurements. For the recently launched Aquarius/Satelite de Aplicaciones Cientificas-D ( SAC-D ; Lagerloef et al. 2008 ; Lagerloef 2012 ) and Soil Moisture and Ocean Salinity ( SMOS ; Font et al. 2010 ) satellite missions dedicated to measuring sea surface salinity (SSS), comparison between retrieved and in situ observations is
1. Introduction An important component of the calibration and validation effort of any satellite mission is the comparison between remotely sensed and in situ measurements. For the recently launched Aquarius/Satelite de Aplicaciones Cientificas-D ( SAC-D ; Lagerloef et al. 2008 ; Lagerloef 2012 ) and Soil Moisture and Ocean Salinity ( SMOS ; Font et al. 2010 ) satellite missions dedicated to measuring sea surface salinity (SSS), comparison between retrieved and in situ observations is
1. Introduction Recent satellite missions to measure ocean near-surface salinity (NSS) have been mainly justified with the idea that they could be used to measure changes in rainfall more effectively than previously possible. This is the idea of using NSS as an “oceanic rain gauge” articulated by Lagerloef et al. (2008) . In the original concept, this rain gauge operated on climate time scales and would be used to test the hypothesis that the global water cycle is accelerating due to a
1. Introduction Recent satellite missions to measure ocean near-surface salinity (NSS) have been mainly justified with the idea that they could be used to measure changes in rainfall more effectively than previously possible. This is the idea of using NSS as an “oceanic rain gauge” articulated by Lagerloef et al. (2008) . In the original concept, this rain gauge operated on climate time scales and would be used to test the hypothesis that the global water cycle is accelerating due to a
consider vertical gradients of temperature T z < 0 and salinity S z < 0, such that no small-scale double-diffusive convection is initially present (cf. Simeonov and Stern 2007 ); such conditions exist in the Arctic Ocean above the Atlantic water. In the presence of horizontal gradients, this basic state is unstable to lateral intrusions driven by the molecular diffusivities ( Holyer 1983 ). The amplifying intrusion shear will rotate the undisturbed isotherms (isohalines), thereby generating an
consider vertical gradients of temperature T z < 0 and salinity S z < 0, such that no small-scale double-diffusive convection is initially present (cf. Simeonov and Stern 2007 ); such conditions exist in the Arctic Ocean above the Atlantic water. In the presence of horizontal gradients, this basic state is unstable to lateral intrusions driven by the molecular diffusivities ( Holyer 1983 ). The amplifying intrusion shear will rotate the undisturbed isotherms (isohalines), thereby generating an
Comparison of Distributional Statistics of Aquarius and Argo Sea Surface Salinity Measurements1. Introduction In 2011, NASA launched a satellite mission to measure sea surface salinity (SSS) and to provide the global view of salinity variability needed for climate studies. The goal of the Aquarius mission is to understand “the interaction between ocean circulation, the water cycle, and climate by measuring salinity” ( NASA 2012 ). Salinity affects the interaction between ocean circulation and the global water cycle, which in turn affects the regulation of the earth’s climate through
1. Introduction In 2011, NASA launched a satellite mission to measure sea surface salinity (SSS) and to provide the global view of salinity variability needed for climate studies. The goal of the Aquarius mission is to understand “the interaction between ocean circulation, the water cycle, and climate by measuring salinity” ( NASA 2012 ). Salinity affects the interaction between ocean circulation and the global water cycle, which in turn affects the regulation of the earth’s climate through
1. Introduction a. The SMOS mission In May 1999 the European Space Agency (ESA) approved the Soil Moisture and Ocean Salinity (SMOS) Mission as the second of its Living Planet Programme Earth Explorer Opportunity Missions to provide global and frequent soil moisture and sea surface salinity (SSS) maps. SMOS was launched on 2 November 2009, and after the first calibration and checkout period (the so-called “commissioning phase”), SSS level 3 products will be distributed; the expected accuracy is
1. Introduction a. The SMOS mission In May 1999 the European Space Agency (ESA) approved the Soil Moisture and Ocean Salinity (SMOS) Mission as the second of its Living Planet Programme Earth Explorer Opportunity Missions to provide global and frequent soil moisture and sea surface salinity (SSS) maps. SMOS was launched on 2 November 2009, and after the first calibration and checkout period (the so-called “commissioning phase”), SSS level 3 products will be distributed; the expected accuracy is
