Direct comparison of surface water dynamics between models and satellites achieved by the latest global river model [CaMa-Flood ver.4]
Abstract
Satellite measurements of surface water dynamics (e.g. water level, flood extent) are valuable information to understand global hydrological cycle, and they are widely used to evaluate global river model simulations. However, direct comparison between models and satellite measurements had been difficult because of the biases in model simulations due to large uncertainties in baseline topography and forcing weather data, and usually relative-values (e.g. anomaly, magnitude, seasonal cycle) are used for model evaluation. Here, we developed a new version of the state-of-the-art global river model [CaMa-Flood ver.4] using the high-accuracy global topography map [MERIT DEM/MERIT Hydro]. The high accuracy baseline topography data largely improved the reality of simulated water levels and flood extents, and achieved the direct comparison with satellite measurements (i.e. absolute-value comparison at all time-step, rather than relative-value comparison). Also, because the uncertainties of the simulated water level and flood extents due to baseline topography map become smaller, it is easier to attribute the source of the remaining errors to the model parameters (such as bathymetry or roughness) and forcing weather data. Using these advantages of the improved model, an advanced use of satellites measurement of surface waters such as calibration and data assimilation are now possible, and step-up from simulation to monitoring is expected in surface water monitoring studies. CaMa-Flood ver.4 http://hydro.iis.u-tokyo.ac.jp/~yamadai/cama-flood/ Related studies: Zhou et al (2021): Toward Improved Comparisons Between Land-Surface-Water-Area Estimates From a Global River Model and Satellite Observations https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020WR029256 Zhou et al. (2021): The uncertainty of flood frequency analyses in hydrodynamic model simulations https://nhess.copernicus.org/articles/21/1071/2021/ Revel et al. (2021): A Framework for Estimating Global-Scale River Discharge by Assimilating Satellite Altimetry https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020WR027876
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H35V1287Y