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Salinity fronts in the tropical Pacific Ocean.

Kao HY, Lagerloef GS - J Geophys Res Oceans (2015)

Bottom Line: In the eastern Pacific, we observe a southward extension of the SF in the boreal spring that could be driven by both precipitation and horizontal advection.In the western Pacific, the importance of these newly resolved SF associated with the western Pacific warm/fresh pool and El Niño southern oscillations are also discussed in the context of prior literature.The main conclusions of this study are that (a) Aquarius satellite salinity measurements reveal the heretofore unknown proliferation, structure, and variability of surface salinity fronts, and that (b) the fine-scale structures of the SF in the tropical Pacific yield important new information on the regional air-sea interaction and the upper ocean dynamics.

View Article: PubMed Central - PubMed

Affiliation: Earth and Space Research Seattle, Washington, USA.

ABSTRACT

This study delineates the salinity fronts (SF) across the tropical Pacific, and describes their variability and regional dynamical significance using Aquarius satellite observations. From the monthly maps of the SF, we find that the SF in the tropical Pacific are (1) usually observed around the boundaries of the fresh pool under the intertropical convergence zone (ITCZ), (2) stronger in boreal autumn than in other seasons, and (3) usually stronger in the eastern Pacific than in the western Pacific. The relationship between the SF and the precipitation and the surface velocity are also discussed. We further present detailed analysis of the SF in three key tropical Pacific regions. Extending zonally around the ITCZ, where the temperature is nearly homogeneous, we find the strong SF of 1.2 psu from 7° to 11°N to be the main contributor of the horizontal density difference of 0.8 kg/m(3). In the eastern Pacific, we observe a southward extension of the SF in the boreal spring that could be driven by both precipitation and horizontal advection. In the western Pacific, the importance of these newly resolved SF associated with the western Pacific warm/fresh pool and El Niño southern oscillations are also discussed in the context of prior literature. The main conclusions of this study are that (a) Aquarius satellite salinity measurements reveal the heretofore unknown proliferation, structure, and variability of surface salinity fronts, and that (b) the fine-scale structures of the SF in the tropical Pacific yield important new information on the regional air-sea interaction and the upper ocean dynamics.

No MeSH data available.


Sea surface salinity (SSS) maps in October 2012 obtained from (a) Argo floats and (b) Aquarius satellite. Figures 2d and 2e show the horizontal gradients of SSS (in psu/km) calculated from Figures 2a and 2b, respectively. The black contours in Figure 2a, 2b, 2d, and 2e) indicate the 34.6 isohalines. Figure 2c shows the difference between Figures 2a and 2b, and Figure 2f shows the difference between Figures 2d and 2e. The black contours in Figure 2c and 2f indicate the 100 mm/month isoline for the precipitation.
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fig02: Sea surface salinity (SSS) maps in October 2012 obtained from (a) Argo floats and (b) Aquarius satellite. Figures 2d and 2e show the horizontal gradients of SSS (in psu/km) calculated from Figures 2a and 2b, respectively. The black contours in Figure 2a, 2b, 2d, and 2e) indicate the 34.6 isohalines. Figure 2c shows the difference between Figures 2a and 2b, and Figure 2f shows the difference between Figures 2d and 2e. The black contours in Figure 2c and 2f indicate the 100 mm/month isoline for the precipitation.

Mentions: SSS maps in October 2012, one of the months with the most evident SF, are shown in Figure 2 to demonstrate the gain in SSS spatial resolution from gridded Aquarius satellite data relative to the smoothed gridded Argo data. A band of low SSS under the Pacific ITCZ and two major fresh pools on both sides of the tropical Pacific are observed in both maps (Figures 2a and 2b). In contrast to the very smooth Argo salinity map, 1° × 1° SSS map from Aquarius satellite shows more detailed structures. Figure 2c shows the value of Aquarius SSS minus Argo SSS. The negative value along the ITCZ is partly due to the stratification of salinity. Aquarius observes the skin salinity and is systematically fresher than Argo data (which is sampled around 5 m depth). The positive values in Figure 2c indicate the mislocation of the boundary of the freshwater in the Argo data.


Salinity fronts in the tropical Pacific Ocean.

Kao HY, Lagerloef GS - J Geophys Res Oceans (2015)

Sea surface salinity (SSS) maps in October 2012 obtained from (a) Argo floats and (b) Aquarius satellite. Figures 2d and 2e show the horizontal gradients of SSS (in psu/km) calculated from Figures 2a and 2b, respectively. The black contours in Figure 2a, 2b, 2d, and 2e) indicate the 34.6 isohalines. Figure 2c shows the difference between Figures 2a and 2b, and Figure 2f shows the difference between Figures 2d and 2e. The black contours in Figure 2c and 2f indicate the 100 mm/month isoline for the precipitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508928&req=5

fig02: Sea surface salinity (SSS) maps in October 2012 obtained from (a) Argo floats and (b) Aquarius satellite. Figures 2d and 2e show the horizontal gradients of SSS (in psu/km) calculated from Figures 2a and 2b, respectively. The black contours in Figure 2a, 2b, 2d, and 2e) indicate the 34.6 isohalines. Figure 2c shows the difference between Figures 2a and 2b, and Figure 2f shows the difference between Figures 2d and 2e. The black contours in Figure 2c and 2f indicate the 100 mm/month isoline for the precipitation.
Mentions: SSS maps in October 2012, one of the months with the most evident SF, are shown in Figure 2 to demonstrate the gain in SSS spatial resolution from gridded Aquarius satellite data relative to the smoothed gridded Argo data. A band of low SSS under the Pacific ITCZ and two major fresh pools on both sides of the tropical Pacific are observed in both maps (Figures 2a and 2b). In contrast to the very smooth Argo salinity map, 1° × 1° SSS map from Aquarius satellite shows more detailed structures. Figure 2c shows the value of Aquarius SSS minus Argo SSS. The negative value along the ITCZ is partly due to the stratification of salinity. Aquarius observes the skin salinity and is systematically fresher than Argo data (which is sampled around 5 m depth). The positive values in Figure 2c indicate the mislocation of the boundary of the freshwater in the Argo data.

Bottom Line: In the eastern Pacific, we observe a southward extension of the SF in the boreal spring that could be driven by both precipitation and horizontal advection.In the western Pacific, the importance of these newly resolved SF associated with the western Pacific warm/fresh pool and El Niño southern oscillations are also discussed in the context of prior literature.The main conclusions of this study are that (a) Aquarius satellite salinity measurements reveal the heretofore unknown proliferation, structure, and variability of surface salinity fronts, and that (b) the fine-scale structures of the SF in the tropical Pacific yield important new information on the regional air-sea interaction and the upper ocean dynamics.

View Article: PubMed Central - PubMed

Affiliation: Earth and Space Research Seattle, Washington, USA.

ABSTRACT

This study delineates the salinity fronts (SF) across the tropical Pacific, and describes their variability and regional dynamical significance using Aquarius satellite observations. From the monthly maps of the SF, we find that the SF in the tropical Pacific are (1) usually observed around the boundaries of the fresh pool under the intertropical convergence zone (ITCZ), (2) stronger in boreal autumn than in other seasons, and (3) usually stronger in the eastern Pacific than in the western Pacific. The relationship between the SF and the precipitation and the surface velocity are also discussed. We further present detailed analysis of the SF in three key tropical Pacific regions. Extending zonally around the ITCZ, where the temperature is nearly homogeneous, we find the strong SF of 1.2 psu from 7° to 11°N to be the main contributor of the horizontal density difference of 0.8 kg/m(3). In the eastern Pacific, we observe a southward extension of the SF in the boreal spring that could be driven by both precipitation and horizontal advection. In the western Pacific, the importance of these newly resolved SF associated with the western Pacific warm/fresh pool and El Niño southern oscillations are also discussed in the context of prior literature. The main conclusions of this study are that (a) Aquarius satellite salinity measurements reveal the heretofore unknown proliferation, structure, and variability of surface salinity fronts, and that (b) the fine-scale structures of the SF in the tropical Pacific yield important new information on the regional air-sea interaction and the upper ocean dynamics.

No MeSH data available.