Tab. 1

Introduction of total column water vapor (TCWV) datasets"

Fig. 1

Distribution of global mean TCWV (a) RSS V7R01; (b), (c), and (d) are differences between SSM/I&SSMIS and RSS V7R01, ERA5 and RSS V7R01, MERRA-2 and RSS V7R01, respectively (units: kg·m-2). R is the correlation coefficient between RSS V7R01 and other datasets Stippling indicates significant at the 95% confidence level using t-test"

Fig. 2

Standard deviation (STD) of monthly mean TCWV (a) RSS V7R01; (b), (c), and (d) are differences between SSM/I&SSMIS and RSS V7R01, ERA5 and RSS V7R01, MERRA-2 and RSS V7R01, respectively (units: kg·m-2). R is the correlation coefficient between RSS V7R01 and other datasets. Stippling indicates significant at the 95% confidence level using t-test"

Fig. 3

Scatter diagrams of TCWV anomalies and SST anomalies (a), (b), (c), and (d) are SSM/I&SSMIS, RSS V7R01, ERA5, and MERRA-2, respectively. The red line represents the curve fitting. R-square and the regression equation are presented"

Fig. 4

Annual cycle of global mean TCWV (a), (b), and (c) are the Northern Hemisphere, the Southern Hemisphere, and global, respectively"

Fig. 5

Time series of TCWV of the four datasets in four seasons (a) March—May; (b) June—August; (c) September— November; (d) December—February"

Fig. 6

EOF analysis of TCWV in the tropical Pacific (a), (b), (c), and (d) are SSM/I&SSMIS, RSS V7R01, ERA5, and MERRA-2, respectively. Shading indicates the structure of the first mode, numbers at the upper right corner are the variance contributions of the first principal components. e shows the time coefficient of the first mode and Ni?o-3.4 index (ONI index)"

Fig. 7

Time series (11-month running smoother applied) and the linear fitting trend of global ocean TCWV anomalies from 1988 to 2018 Red, yellow, and black lines represent the linear trends of 1988—1998, 1999—2008, and 2009—2018, respectively"

Fig. 8

Zonal mean of global TCWV (with seasonal cycle removed) (a), (b), (c), and (d) are SSM/I&SSMIS, RSS V7R01, ERA5, and MERRA-2, respectively"

Fig. 9

Spatial distribution of long-term trend of global ocean TCWV (1988—2018) (a), (b), (c), and (d) are SSM/I&SSMIS, RSS V7R01, ERA5, and MERRA-2, respectively. Shading indicates long-term trend. Stippling indicates significant at the 95% confidence level using F-test"