Table 2.

Details of each QC check for RODCCS.

Order	Name of QC	Descriptions	Variables for check
1	Location check	Check whether data are in the region of 116°E - 135°E in longitude and 20°N - 42°N in latitude.	All 12 variables
2	Depth check	Check whether data depth exceeds local bottom depth according to the GEBCO dataset or is above the sea level.	All 12 variables
3	Constant value check	Check whether the exact same value occurs three or more times consecutively within a single cruise or sampling event.	All 12 variables
4	Value range check	Check whether data values fall within the statistical and published observational ranges. For variables that conform to the normal distribution or approximately normal distribution, the Chauvenet’s criterion is applied to determine the statistically empirical ranges. For those that do not conform to, the IQR method is used.	All 12 variables
5	Vertical gradient check	Check whether the vertical gradient exceeds the empirical thresholds of vertical gradient. For each sampling event, the value of the initial sampling point is first validated against the WOA13 data to ensure its rationality. Subsequently, the vertical gradient between every sampling point and its shallower sampling point is assessed to determine whether it falls within the corresponding vertical gradient range described in Table 5.	Temperature, salinity, DO, silicate, nitrate, phosphate
6	Time reversal check	Check if data points with precise sampling times (down to hours and minutes) show increasing temporal records within an individual cruise.	All 12 variables