Robock_Pub_9
Robock, Alan, Konstantin Ya. Vinnikov, C. Adam
Schlosser, Nina A. Speranskaya, and Yongkang Xue, 1995: Use of
midlatitude soil moisture and meteorological observations to
validate soil moisture simulations with biosphere and bucket
models. J. Climate, 8, 15-35.
ABSTRACT:
Soil moisture observations in sites with natural vegetation were
made for several decades in the former Soviet Union at hundreds of
stations. In this paper, we use data from 6 of these stations from
different climatic regimes, along with ancillary meteorological and
actinometric data, to demonstrate a method to validate soil
moisture simulations with biosphere and bucket models. Some
early and current general circulation models (GCMs) use bucket
models for soil hydrology calculations. More recently, the Simple
Biosphere Model (SiB) was developed to incorporate the effects of
vegetation on fluxes of moisture, momentum, and energy at the
earth's surface into soil hydrology models. Until now, the bucket
and SiB have been verified by comparison with actual soil moisture
data only on a limited basis. In this study, a Simplified SiB (SSiB)
soil hydrology model and a 15-cm bucket model are forced by
observed meteorological and actinometric data every 3 hours for 6-
year simulations at the 6 stations. The model calculations of soil
moisture are compared to observations of soil moisture, literally
"ground truth," snow cover, surface albedo, and net radiation, and
with each other.
For three of the stations, the SSiB and 15-cm bucket models
produce good simulations of seasonal cycles and interannual
variations of soil moisture. For the other three stations, there are
large errors in the simulations by both models. Inconsistencies in
specification of field capacity may be partly responsible. There is
no evidence that the SSiB simulations are superior in simulating soil
moisture variations. In fact the models are quite similar, since SSiB
implicitly has a bucket embedded in it. One of the main differences
between the models is in the treatment of runoff due to melting
snow in the spring - SSiB incorrectly puts all the snowmelt into
runoff. While producing similar soil moisture simulations, the
models produce very different surface latent and sensible heat
fluxes, which would have large effects on GCM simulations.
Prepared by Alan Robock (robock@envsci.rutgers.edu ) -
Last updated on February 2, 1999