Simulated terrestrial water storage (TWS) is an important source of information for various climate-related geodetic studies, e.g., the evaluation and improvement of satellite gravimetry products, or the correction of GNSS-based coordinate time-series. We employ the open-source hydrological model OS LISFLOOD developed by the Joint Research Centre (JRC) of the European Commission to generate global daily TWS time series, and its individual storage compartments soil moisture, groundwater, surface water, and snow, in a so far unprecedented high spatial resolution of 1/20° over the time period 2000 – 2023. Modeled TWS results from OS LISFLOOD have been shown to be competitive to other state-of-the-art hydrological models, using satellite gravimetric data from GRACE/-FO and GNSS-derived surface displacements for validation.

Recently, a new model version (v5) was developed by the JRC, which is currently being calibrated globally and will be publicly available soon. The new version benefits from several model improvements including an optimized soil depth definition; an improved model initialization; a modified snow routine; and an alternative river routing scheme. Furthermore, the number of lakes and reservoirs explicitly simulated was more than doubled compared to the previous version, and also includes several endorheic lakes now (i.e. lakes without an outlet like the Caspian Sea, Lake Balkhash, or Lake Chad). While endorheic lakes experience considerable water storage variations, they, however, pose a challenge to hydrological modeling as the calibration cannot be done with the classical approach of using river gauges.

In this contribution we show results from a first experiment with the new OS LISFLOOD v5, and evaluate them with respect to previous results, by computing the fit to GRACE/-FO observations on various spatial and temporal scales with different measures (e.g. correlation, RMSD, KGE). We particularly focus on the ability of the new model version to reproduce endorheic lake level changes by utilizing time series from satellite altimetry.

Co-authors:
Robert Dill (1), Stefania Grimaldi (2), and Henryk Dobslaw (1)
(1) GFZ Helmholtz Centre for Geosciences, Potsdam, Germany
(2) European Commission Joint Research Centre, Ispra, Italy