Fig. 1

Location of the Indonesian-Australian Basin in the southeast Indian Ocean (black box on the right panel), distribution of temperature (contours on the left panel) and salinity (filled color on the left panel) within the basin, and location of the three main outflow straits (Lombok Strait, Ombai Strait, and Timor Strait) of the Indonesia Throughflow (ITF) (solid black line on the right panel), and paths of outflow of the water (vector arrows)"

Fig. 2

The left panel shows the buoyancy frequency (a), and the proportion (Prop) of the contribution of its temperature (c) and salinity (e) components at the bottom of pycnocline in the climatology; the right panel shows the IAB mixed layer depth (b), mixed layer temperature (d) and mixed layer salinity (f) in the climatology"

Fig. 3

The left panel shows the seasonal climate state of the buoyancy frequency (a, filled color), and its temperature component (c, filled color) and salinity component (e, filled color) at the bottom of the pycnocline, as well as the seasonal climatology of the mixed layer depth (a, contours), and mixed layer temperature (c, contours) and mixed layer salinity (e, contours), spatial modes of seasonal variation obtained by EOF analysis; the right panel shows the first principal temporal component of the variables of interest, with the explained variance, respectively: N 2(84%), N T 2 (78%), N S 2 (82%), MLD(89%), MLT(95%), MLS(58%)"

Fig. 4

Variation in temperature and salinity obtained by volume averaging over the basin area at 300 m depth (black line), and sea surface fluxes (red line) and advective processes (blue line) affecting temperature (a) and salinity (b) within the basin, with the gray dashed line being the sum of the two; (b) and (d) are the advective contributions of temperature and salinity at the four boundaries, respectively, and the error bars are the seasonal standard deviations of each component"

Fig. 5

Seasonal variation of advection—induced temperature anomalies (a) and salinity anomalies (b) at the eastern boundary of the basin (filled part). The solid gray line is the seasonal variation of the mean vertical potential density profile in the basin, and the solid black line represents positive potential density anomalies in the basin and the dashed black line represents negative potential density anomalies in the basin"

Fig. 6

In the climatological boreal summer, the distribution of buoyancy frequency anomalies due to mixed layer temperature anomalies (a, filled color) and mixed layer salinity anomalies (b, filled color) induced by sea surface fluxes, and the distribution of temperature buoyancy frequency (a, contours) and salinity buoyancy frequency (b, contours) in climatology. Similarly, (c) and (d) are the temperature and salinity anomalies induced by zonal advection respectively, while (e) and (f) are buoyancy frequency anomalies induced by meridional advection, respectively"

Fig. 7

The seasonal variation of the transport of the Indonesian Throughflow in the three main straits (a), (b) is the buoyancy frequency anomaly obtained by the buoyancy frequency from the period of the strong surface transport (red lines in the two shaded parts of the a figure: JAS—NDJ) at the bottom of pycnocline, and the horizontal distribution of the buoyancy frequency component due to the vertical gradient of temperature (c) and salinity(d), which are associated with the variation of the transport of Indonesian Throughflow (d)"

Fig. 8

The seasonal variation of the transport of the Indonesian Throughflow in the three main straits (a), (b) is the buoyancy frequency anomaly zonal profile obtained by the buoyancy frequency from the period of the strong surface transport(red lines in the two shaded parts of the a figure: JAS—NDJ) at the bottom of the mixed layer, and the vertical distribution of the buoyancy frequency component due to the vertical gradient of temperature (c) and salinity (d), which are associated with the variation of the transport of Indonesian Throughflow (d)"

Fig. 9

In the climatology, the horizontal (a, c) and vertical (b, d) distributions of the correlation coefficients between the surface (a, b) and subsurface (c, d) transport of Indonesian Throughflow in the straits (ahead 3 months) and the buoyancy frequency at the bottom of pycnocline in the IAB; as well as lead\lag correlation coefficient between the buoyancy frequency averaged over the IAB and the transport of Indonesian Throughflow (f), and the linear coefficients (e) that regress the surface (red) and subsurface transport (blue) of the straits transport to the buoyancy frequency at bottom of pycnocline. Marks represent the sea area of correlation coefficients above the 95% confidence level"