Here you will see the monthly diagnostic surface runoff and soil moisture fields
from NOAA NCEP-NCAR Climate Data
Assimilation System I (CDAS-1). The CDAS-1 runs from Jan 1974 to present (May 1997, currently).
The spatial distributions of surface runoff and soil moistures (0-10, 10-200 cm two
layers) in four months in 1996 are shown in the following plots.
The unit for surface runoff is kg/m^2/day, and for soil moisture is volumetric fraction.
The TOPEX/POSEIDON altimeter provides accurate determination of global sea surface topography. The global
mean sea level (MSL) variation with long term trend removed may tell us the water mass redistribution
among the atmosphere, continents, oceans, and ice sheet. Using the available information from NCEP-NCAR
CDAS-1, TOPEX/POSEIDON, and WOA94, we could well predict the observed seasonal global MSL (associated with
water mass change).
The global MSL variations are predicted by integrating the total precipitable water mass variations in the atmosphere
(CDAS-1), in soil moisture (0-200 cm depth, CDAS-1), and in the accumulated snow field (CDAS-1).
The global MSL variations induced by thermal expansion are estimated using the objectively
analyzed temperature fields in the World Ocean Atlas 1994 (WOA94). With the steric MSL variation removed, the
residual global MSL matches quite well with the predicted MSL (See the following plot).