Spatial and temporal characteristics of moisture cycle factors over China analyzed with ERA-Interim reanalysis data

Abstract

In this paper, we analyze the spatial and temporal characteristics of different moisture cycle factors over China by using the ERA-Interim data supplied by the European Centre for medium-range weather forecasts (ECMWF). The methods used in this paper include mainly the empirical orthogonal function (EOF), similarity coefficients, one-dimensional linear regression and so on. Results show that the spatial distribution of evaporation, zonal and meridional moisture flux are all extremely similar to that of precipitable water. While the spatial distribution of precipitable water and precipitation are both very similar to that of evaporation. The similarity coefficient between precipitation and zonal moisture flux is a little larger than that between precipitation and meridional moisture flux. In terms of temporal characteristics, it is shown that precipitation has an obvious upward trend during 1979–2002 and an obvious downward trend during 2002–2011. The trend of evaporation is the same as that of precipitation during the same period, but the former is more obvious than the latter. Besides, evaporation also shows an obvious upward trend during 1979–2011. Both of precipitable water and moisture flux divergence show a slightly downword trend. Zonal and meridional moisture flux change in a period of 2–3 years. Further, zonal moisture flux has an obvious downward trend during 1979–2011. The vapor flux has an obvious downward trend both in spring and autumn, and changes in a period of 2–3 years for all four seasons. Besides, the vapor flux in summer presents a decadal transition.