Fig. 1

Long-term mean sea surface salinity (a), standard deviation of the seasonal variability of sea surface salinity (b), surface temperature (c) and surface currents (d). The red contour denotes the annual mean 34‰ isohaline. The vector and shading represent sea surface current and its zonal component, respectively. The positive value of shading represents eastward current"

Fig. 2

Seasonal variability of sea surface salinity. Mar-May (a); June-August (b); September-November (c); December-February (d). The black contour denotes seasonal 34‰ isohalines, and the red denotes the annual mean 34‰ isohaline"

Fig. 3

Seasonal variability of the eastern tropical Pacific freshwater pool. (a) The EPFP volume (dashed line) and area (solid line); (b) the deepest depth (dashed line) and westernmost longitude (solid line) of the EPFP; (c) the mean of the sea surface salinity and the salinity in the whole EPFP; (d) the mean precipitation and sea level anomaly in the EPFP"

Fig. 4

Seasonal variability of the precipitation (shading) and surface wind (arrows) in the eastern tropical Pacific. Mar-May (a); June-August (b); September-November (c); December-February (d). The black contour denotes seasonal 34‰ isohalines, the red denotes the annual mean 34‰ isohaline, and the blue denotes the seasonal position of the intertropical convergence zone"

Fig. 5

Seasonal variabilities of precipitation (a), mixed layer depth (b), Ekman pumping (c), and zonal velocity (d) along 10°N. The red contour denotes the western boundary of the EPFP (34‰ isohaline)"

Fig. 6

Comparison of long-term mean mixed layer salinity budget in the eastern tropical Pacific. Shown are surface forcing (a, c), horizontal advection (b, d) and subsurface processes (e). (a) and (b) are estimated using observations; (c), (d) and (e) are estimated using ECCO-JPL. The red contour is the annual mean 34‰ isohaline"

Fig. 7

Seasonal variabilities of the sea surface salinity (a), surface freshwater flux (b) and mixed layer salinity budget terms (c, d, e, f). All values are averaged in the black box of Fig. 6a. The black dashed line in (a) is estimated from Argo data. The black dashed line in (b) is estimated from OAFlux (evaporation) and GPCP (precipitation), and ECCO-JPL. The solid lines in (a) and (b) are calculated from ECCO-JPL. dsdt represents the mixed layer salinity tendency; SF represents sea surface forcing; ODY is oceanic dynamics, consisting of horizontal advection and subsurface processes (Sub); Adv-x and Adv-y represent the zonal and meridional components of the horizontal advection, respectively"