Controlling factors of latitudinal distribution of dissolved organic matter in the upper layers of the Indian Ocean

Progress in Earth and Planetary Science

Table 1 Correlation coefficients between each pair of observed variables in the surface mixed layer

	a₂₅₄	a₃₂₅	C1	C2	C3	S_275–295	a_254/365	BIX	HIX
DOC	0.86^***	0.27^*	− 0.08	− 0.09	0.74^***	0.70^***	0.32^*	0.36^**	− 0.72^***
a₂₅₄		0.58^***	0.27^*	0.21	0.84^***	0.43^***	− 0.01	0.12	− 0.47^***
a₃₂₅			0.61^***	0.56^***	0.43^***	− 0.40^**	− 0.70^***	− 0.28^*	− 0.20
C1				0.88^***	0.35^**	− 0.58^***	− 0.67^***	− 0.40^**	0.54^***
C2					0.36^**	− 0.54^***	− 0.61^***	− 0.29^*	0.51^***
C3						0.39^**	0.05	0.17	− 0.51^***
S_275–295							0.78^***	0.54^***	− 0.87^***
a_254/365								0.47^***	− 0.65^***
BIX									− 0.41^**

Absolute values of correlation coefficient greater than or equal to 0.7 are indicated in bold. * p < 0.05, ** p < 0.01, and *** p < 0.001. Dissolved organic carbon (DOC), CDOM absorption coefficient at wavelength λ (a_λ (m⁻¹)), components determined using PARAFAC analysis (C1–C3), spectral slope coefficient between 275 and 295 nm (S_275–295), absorption coefficient ratio at 254 and 365 nm (a_254/365), biological index (BIX), and humification index (HIX)