The annual cycle of terrestrial water storage anomalies in CMIP6 models evaluated against GRACE data
Journal
Journal of Climate
Journal Volume
34
Journal Issue
20
Pages
8205-8217
Date Issued
2021
Author(s)
Abstract
The terrestrial water storage anomaly (TWSA) is a critical component of the global water cycle where improved spatiotemporal dynamics would enhance exploration of weather- and climate-linked processes. Thus, correctly simulating TWSA is essential not only for water-resource management but also for assessing feedbacks to climate through land-atmosphere interactions. Here we evaluate simulated TWSA from 25 climate models (from phase 6 of the Climate Model Intercomparison Project) through comparison with TWSA from GRACE satellite data (2003-14) in 14 river basins globally and assess causes of discrepancies by examining precipitation (P), evapotranspiration (ET), and runoff (Roff) fluxes during recharge (increasing TWS) and discharge (decreasing TWS) cycles. Most models show consistent biases in seasonal amplitudes of TWS anomalies relative to GRACE output: higher modeled amplitudes in river basins in high northern latitudes and the Parana and Congo basins, and lower amplitudes in most midlatitude basins and other tropical basins. This TWSA systematic bias also exists in the previous CMIP5 simulations. Models overestimate P compared to observed P datasets in 7 out of 14 basins, which increases (decreases) seasonal storage amplitude relative to GRACE in the recharge (discharge) cycle. Overestimation (underestimation) of runoff is another common contributing factor in the discharge phase that increases (decreases) TWSA amplitudes relative to GRACE in five river basins. The results provide a comprehensive assessment of the reliability of the simulated annual range in TWSA through comparison with GRACE data that can be used to guide future model development. ? 2021 American Meteorological Society.
Subjects
Evapotranspiration
Hydrologic cycle
Precipitation
Runoff
Satellite observations
Water masses/storage
Digital storage
Geodetic satellites
Rivers
Water management
Water supply
Watersheds
Annual cycle
Critical component
Global water cycle
Hydrologic cycles
Mass storage
River basins
Terrestrial water storage
Water mass
Water mass/storage
Climate models
annual variation
CMIP
data set
evapotranspiration
GRACE
hydrological cycle
precipitation assessment
runoff
satellite imagery
spatiotemporal analysis
water mass
Type
journal article