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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.


Maps of the SSS fronts (left), SST fronts (middle) and the density fronts (right) in January, April, July, and October. The units are in psu/km, °C/km, and kg/m3/km, respectively.
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fig05: Maps of the SSS fronts (left), SST fronts (middle) and the density fronts (right) in January, April, July, and October. The units are in psu/km, °C/km, and kg/m3/km, respectively.

Mentions: We calculated the sea surface density (SSD) to study in more detail the effects of the SF on the upper ocean dynamics. The equation of state was used to combine the high-resolution of SSS data from Aquarius and the SST data from NOAA OISST. We located the density fronts in the tropical Pacific from calculating the horizontal density gradients substituting density for salinity in equation (1) and show the results in in Figure 5 (right). Comparing with the SF and the SST fronts, we then evaluate which part of the density fronts are contributed by the SSS or by the SST. As discussed, the SF are most evident at the boundaries of ITCZ and the edges of the fresh pools. The SST fronts (Figure 5, middle) are most evident in the equatorial central to eastern Pacific and the north boundaries of the eastern Pacific warm pool. The SST over the WPWP is so homogeneous that SST fronts are weak in the western Pacific. Density fronts reflect the locations of both the SF and the SST fronts. The locations of SST and SSS fronts have already been shown to influence the TIW dynamics [Lee et al., 2012]. These results are described in the context of the regional SF discussions in the following sections.


Salinity fronts in the tropical Pacific Ocean.

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

Maps of the SSS fronts (left), SST fronts (middle) and the density fronts (right) in January, April, July, and October. The units are in psu/km, °C/km, and kg/m3/km, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig05: Maps of the SSS fronts (left), SST fronts (middle) and the density fronts (right) in January, April, July, and October. The units are in psu/km, °C/km, and kg/m3/km, respectively.
Mentions: We calculated the sea surface density (SSD) to study in more detail the effects of the SF on the upper ocean dynamics. The equation of state was used to combine the high-resolution of SSS data from Aquarius and the SST data from NOAA OISST. We located the density fronts in the tropical Pacific from calculating the horizontal density gradients substituting density for salinity in equation (1) and show the results in in Figure 5 (right). Comparing with the SF and the SST fronts, we then evaluate which part of the density fronts are contributed by the SSS or by the SST. As discussed, the SF are most evident at the boundaries of ITCZ and the edges of the fresh pools. The SST fronts (Figure 5, middle) are most evident in the equatorial central to eastern Pacific and the north boundaries of the eastern Pacific warm pool. The SST over the WPWP is so homogeneous that SST fronts are weak in the western Pacific. Density fronts reflect the locations of both the SF and the SST fronts. The locations of SST and SSS fronts have already been shown to influence the TIW dynamics [Lee et al., 2012]. These results are described in the context of the regional SF discussions in the following sections.

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.