Journal Article

Evaluation of CMIP6 Global Climate Models for Simulating Land Surface Energy and Water Fluxes During 1979–2014

Li, Jianduo, Miao, Chiyuan, Wei, Wei, Hua, Lijuan, Zhang, Guo, Wang, Xiaoxiao, Chen, Yueli

2021

Overview

This study examined the overall performance of the climate models in Phase 6 of the Coupled Model Intercomparison Project (CMIP6) in simulating the key energy and water fluxes over land. For this purpose, this study selected multiple land flux products as reference data sets and assessed the global spatial means, patterns, trends, seasonal cycles, and regional mean estimates of the sensible heat (SH), latent heat (LH), net radiation (RN), runoff (RF), and precipitation (PR) simulated by 32 CMIP6 models in recent decades. The global (Antarctica, Greenland, and hot deserts are not included) mean SH, LH, RN, RF, and PR simulated by the CMIP6 models are 37.55 ± 4.81 W m−2, 49.88 ± 5.31 W m−2, 89.10 ± 4.45 W m−2, 351.31 ± 95.28 mm yr−1, and 948.35 ± 88.77 mm yr−1, respectively. The ensemble median of CMIP6 simulations (CMIP6‐MED) can provide robust estimates of global and regional land fluxes, which are within the ranges given by the reference data sets, and highly consistent spatiotemporal patterns of these fluxes. The comparison of CMIP6‐MED with the first preferred reference data sets shows that CMIP6‐MED generally overestimates the water and energy fluxes over land, except for the simulated RF and PR in the Amazon region. The most disagreements between CMIP6‐MED and the reference data sets occur in South America (particularly the Amazon region) and the Tibetan Plateau. Finally, the sources of model biases are discussed. It is suggested that current land flux products should be widely used to optimize the structures and parameters of climate models in future work. Plain Language Summary Land surface models are an indispensable part of weather and climate models. Sensible heat (SH), latent heat (LH), net radiation (RN), runoff (RF), and precipitation (PR) are the key components of the energy and water cycles over global land. This study evaluated these five fluxes from 1979 to 2014 simulated by 32 climate models in Phase 6 of the Coupled Model Intercomparison Project (CMIP6), with multiple global land products. The RN and RF estimated by the CMIP6 models exhibit the lowest and highest uncertainties, respectively. The ensemble median of CMIP6 simulations (CMIP6‐MED) provides robust estimates of global and regional land fluxes, which are within reference ranges. We select the first preferred reference data sets from multiple global land products according to the evaluations against site observations and previous studies, and find that CMIP6‐MED generally overestimates the water and energy fluxes over land. The most disagreements between CMIP6 simulations and references occur in South America and the Tibetan Plateau. This study is helpful for determining the overall performance of the current climate models in simulating land surface processes. Key Points Performance of CMIP6 models on land surface energy and water fluxes during 1979–2014 is comprehensively evaluated using multiple land flux products Ensemble median of CMIP6 simulations can provide robust estimates of global and regional land fluxes, which are within the ranges given by reference data sets The most disagreements between CMIP6 simulations and reference data sets occur in South America (particularly the Amazon region) and the Tibetan Plateau

• Publisher: John Wiley & Sons, Inc,American Geophysical Union (AGU)
• Subject: Accuracy / Climate / Climate change / Climate models / CMIP6 / Data / Datasets / Energy / energy flux / Freshwater resources / Global climate / Intercomparison / land surface model / Latent heat / Machine learning / model evaluation / Net radiation / Precipitation / Radiation / Radiation balance / Remote sensing / Runoff / Seasonal variation / Sensible heat / Simulation / water flux