Moisture transport to continents under warming climate

Understanding the water cycle change under the warming climate is essential, particularly the ocean to land moisture transport, which affects the precipitation over land areas. Using ERA5 data and satellite observations from 1979-2020, the moisture transport and its trend around the boundary of each continent, including the Eurasia, Africa, North America, South America, Antarctic, Australia and Greenland, have been investigated. The inflow and outflow sections of the moisture have been identified for each continent. The trends of moisture convergence over Eurasia, Africa, North America, Antarctic and Australia have positive trends, with the value of 1.78±3.11, 2.43±3.16, 12.92±2.27 and 0.34±0.45 (in 10⁶ kg/s/decade), respectively, but only the trend of 12.92±2.27 (in 10⁶ kg/s/decade) over North America is significant at 0.1 significance level. The moisture convergence trend of −0.87±3.64 (in 10⁶ kg/s/decade) over South America is negative but insignificant. The positive trend of 0.04±0.35 (in 10⁶ kg/s/decade) over Greenland is very weak.

Both evaporation and moisture convergence (or transport) contribute to the continental precipitation, but the convergence dominates the precipitation variability over all continents, and the correlation coefficients between the time series of continental mean convergence and precipitation anomalies are higher than 0.8 in all continents.