|
Abstract. The partitioning of precipitation into runoff (R)
and evapotranspiration (E), governed by the controlling parameter
in the Budyko framework (i.e., n parameter in the
Choudhury and Yang equation), is critical to assessing the
water balance at global scale. It is widely acknowledged that
the spatial variation in this controlling parameter is affected
by landscape characteristics, but characterizing its temporal
variation remains yet to be done. Considering effective precipitation
(Pe), the Budyko framework was extended to the
annual water balance analysis. To reflect the mismatch between
water supply (precipitation, P) and energy (potential
evapotranspiration, E0), we proposed a climate seasonality
and asynchrony index (SAI) in terms of both phase and amplitude
mismatch between P and E0. Considering streamflow
changes in 26 large river basins as a case study, SAI
was found to the key factor explaining 51% of the annual
variance of parameter n. Furthermore, the vegetation dynamics
(M) remarkably impacted the temporal variation in n,
explaining 67% of the variance. With SAI and M, a semiempirical
formula for parameter n was developed at the annual
scale to describe annual runoff (R) and evapotranspiration
(E). The impacts of climate variability (Pe, E0 and SAI)
and M on R and E changes were then quantified. Results
showed that R and E changes were controlled mainly by the
Pe variations in most river basins over the globe, while SAI
acted as the controlling factor modifying R and E changes
in the East Asian subtropical monsoon zone. SAI, M and E0
have larger impacts on E than on R, whereas Pe has larger
impacts on R.
Archiver|手机版|科学网 ( 京ICP备07017567号-12 )
GMT+8, 2024-3-28 20:08
Powered by ScienceNet.cn
Copyright © 2007- 中国科学报社